The International Ice Patrol (IIP) was established after the Titanic collided with an iceberg off the eastern coast of Canada in 1912 and sank, killing more than 1,500 people. Recently, the IIP has analyzed satellite images and provided safe operation information to vessels by tracking the occurrence and movement of icebergs. A large number of recent arctic studies mainly deal with sea ice formed by freezing seawater related to sea routes and resource development. The iceberg that collided with the Titanic was land-based ice that dislodged from a glacier and fell into the sea. The properties of these two types of ice are different. In addition, vessels operating in ice-covered waters such as the Arctic sea have an ice-breaking function or minimum ice-strengthened functions. Ships operating on transatlantic routes including the eastern coast of Canada do not necessarily require ice-strengthened functions. Hundreds to thousands of icebergs are discovered each year near the area where the Titanic sank. In this study, the status of ship-iceberg collision accidents was investigated to provide useful information to researchers, and the physical and mechanical characteristics of icebergs were investigated and summarized.
{"title":"Review of Ice Characteristics in Ship-Iceberg Collisions","authors":"Tak-Kee Lee, Hyun-Jin Park","doi":"10.26748/ksoe.2021.060","DOIUrl":"https://doi.org/10.26748/ksoe.2021.060","url":null,"abstract":"The International Ice Patrol (IIP) was established after the Titanic collided with an iceberg off the eastern coast of Canada in 1912 and sank, killing more than 1,500 people. Recently, the IIP has analyzed satellite images and provided safe operation information to vessels by tracking the occurrence and movement of icebergs. A large number of recent arctic studies mainly deal with sea ice formed by freezing seawater related to sea routes and resource development. The iceberg that collided with the Titanic was land-based ice that dislodged from a glacier and fell into the sea. The properties of these two types of ice are different. In addition, vessels operating in ice-covered waters such as the Arctic sea have an ice-breaking function or minimum ice-strengthened functions. Ships operating on transatlantic routes including the eastern coast of Canada do not necessarily require ice-strengthened functions. Hundreds to thousands of icebergs are discovered each year near the area where the Titanic sank. In this study, the status of ship-iceberg collision accidents was investigated to provide useful information to researchers, and the physical and mechanical characteristics of icebergs were investigated and summarized.","PeriodicalId":315103,"journal":{"name":"Journal of Ocean Engineering and Technology","volume":"267 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127546221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: The need for energy harvesting in marine environments is gradually increasing owing to the energy limitation of marine robots. To address this problem, a catamaran-type sail drone (CSD), which can harvest marine energies such as wind and solar, was proposed in a previous study. However, it was designed and manufactured without considering the stability, optimal hull-form, and maintenance. To resolve these problems, a CSD with two keels, a performance estimator, V-shape hulls, and modularized components is proposed and its mechanism is developed in this study. To verify the performance of the CSD, the performance estimation using smoothed-particle hydrodynamics (SPH) and the heading control using fuzzy logic controller (FLC) are performed. Simulation results show the attitude stability of the CSD and the experimental results show the straight path of the CSD according to wind conditions. Therefore, the CSD has potential applications as an energy harvesting system.
{"title":"Mechanism Development and Heading Control of Catamaran-type Sail Drone","authors":"D. Man, Hyun-Sik Kim","doi":"10.26748/ksoe.2021.062","DOIUrl":"https://doi.org/10.26748/ksoe.2021.062","url":null,"abstract":": The need for energy harvesting in marine environments is gradually increasing owing to the energy limitation of marine robots. To address this problem, a catamaran-type sail drone (CSD), which can harvest marine energies such as wind and solar, was proposed in a previous study. However, it was designed and manufactured without considering the stability, optimal hull-form, and maintenance. To resolve these problems, a CSD with two keels, a performance estimator, V-shape hulls, and modularized components is proposed and its mechanism is developed in this study. To verify the performance of the CSD, the performance estimation using smoothed-particle hydrodynamics (SPH) and the heading control using fuzzy logic controller (FLC) are performed. Simulation results show the attitude stability of the CSD and the experimental results show the straight path of the CSD according to wind conditions. Therefore, the CSD has potential applications as an energy harvesting system.","PeriodicalId":315103,"journal":{"name":"Journal of Ocean Engineering and Technology","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125349574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Microcracks can rapidly grow and develop in high-strength steels used in offshore structures. It is important to render these microcracks harmless to ensure the safety and reliability of offshore structures. Here, the dependence of the aspect ratio () of the maximum depth of harmless crack ( ) was evaluated under three different conditions considering the threshold stress intensity factor ( ) and residual stress of offshore structural steel F690. The threshold stress intensity factor and fatigue limit of fatigue crack propagation, dependent on crack dimensions, were evaluated using Ando's equation, which considers the plastic behavior of fatigue and the stress ratio. by peening was analyzed using the relationship between obtained by Ando's equation and obtained by the sum of applied stress and residual stress. The plate specimen had a width 2 = 12 mm and thickness = 20 mm, and four value of As were considered: 1.0, 0.6, 0.3, and 0.1. The was larger as the compressive residual stress distribution increased. Additionally, an increase in the values of As and led to a larger . With a safety factor () of 2.0, the long-term safety and reliability of structures constructed using F690 can be secured with needle peening. It is necessary to apply a more sensitive non-destructive inspection technique as a non-destructive inspection method for crack detection could not be used to observe fatigue cracks that reduced the fatigue limit of smooth specimens by 50% in the three types of residual stresses considered. The usefulness of non-destructive inspection and non-damaging techniques was reviewed based on the relationship between , (minimum crack depth detectable in non-destructive inspection), (crack depth that reduces the fatigue limit to 1/), and As. Received 11 May 2021, revised 21 June 2021, accepted 9 July 2021 Corresponding author Ki-Woo Nam: +82-51-629-6358, namkw@pknu.ac.kr c 2021, The Korean Society of Ocean Engineers This is an open access article distributed under the terms of the creative commons attribution non-commercial license (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
海洋结构中使用的高强度钢存在微裂纹迅速生长和发展的问题。使这些微裂缝无害化对保证海上结构的安全可靠具有重要意义。考虑阈值应力强度因子()和海上结构钢F690的残余应力，在三种不同条件下，对最大无害裂纹深度()的长径比()的依赖关系进行了评价。采用考虑疲劳塑性行为和应力比的Ando方程，计算了裂纹扩展的阈值应力强度因子和裂纹扩展的疲劳极限。利用安藤方程得到的与施加应力和残余应力之和得到的之间的关系，对强化后的进行了分析。板样宽度2 × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × ×。随残余压应力分布的增大而增大。此外，As和的值增加导致变大。F690结构的安全系数()为2.0，针刺强化可以保证结构的长期安全可靠。在考虑三种残余应力的情况下，光滑试样的疲劳极限降低50%，由于无损检测方法无法观察到疲劳裂纹，因此有必要采用更灵敏的无损检测技术。基于、(无损检测中可检测的最小裂纹深度)、(将疲劳极限降低到1/的裂纹深度)和As之间的关系，综述了无损检测和非损伤技术的有用性。通讯作者Ki-Woo Nam: +82-51-629-6358, namkw@pknu.ac.kr c 2021, The Korean Society of Ocean Engineers这是一篇开放获取的文章，根据创作共用归属非商业许可(http://creativecommons.org/licenses/by-nc/4.0)的条款分发，允许在任何媒介上不受限制的非商业使用、分发和复制，前提是原始作品被适当引用。
{"title":"Reliability Improvement of Offshore Structural Steel F690 Using Surface Crack Nondamaging Technology","authors":"Weon-Gu Lee, Kyoung-Hee Gu, Cheol Kim, K. Nam","doi":"10.26748/ksoe.2021.022","DOIUrl":"https://doi.org/10.26748/ksoe.2021.022","url":null,"abstract":"Microcracks can rapidly grow and develop in high-strength steels used in offshore structures. It is important to render these microcracks harmless to ensure the safety and reliability of offshore structures. Here, the dependence of the aspect ratio () of the maximum depth of harmless crack ( ) was evaluated under three different conditions considering the threshold stress intensity factor ( ) and residual stress of offshore structural steel F690. The threshold stress intensity factor and fatigue limit of fatigue crack propagation, dependent on crack dimensions, were evaluated using Ando's equation, which considers the plastic behavior of fatigue and the stress ratio. by peening was analyzed using the relationship between obtained by Ando's equation and obtained by the sum of applied stress and residual stress. The plate specimen had a width 2 = 12 mm and thickness = 20 mm, and four value of As were considered: 1.0, 0.6, 0.3, and 0.1. The was larger as the compressive residual stress distribution increased. Additionally, an increase in the values of As and led to a larger . With a safety factor () of 2.0, the long-term safety and reliability of structures constructed using F690 can be secured with needle peening. It is necessary to apply a more sensitive non-destructive inspection technique as a non-destructive inspection method for crack detection could not be used to observe fatigue cracks that reduced the fatigue limit of smooth specimens by 50% in the three types of residual stresses considered. The usefulness of non-destructive inspection and non-damaging techniques was reviewed based on the relationship between , (minimum crack depth detectable in non-destructive inspection), (crack depth that reduces the fatigue limit to 1/), and As. Received 11 May 2021, revised 21 June 2021, accepted 9 July 2021 Corresponding author Ki-Woo Nam: +82-51-629-6358, namkw@pknu.ac.kr c 2021, The Korean Society of Ocean Engineers This is an open access article distributed under the terms of the creative commons attribution non-commercial license (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.","PeriodicalId":315103,"journal":{"name":"Journal of Ocean Engineering and Technology","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124474292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Myungjun Jeon, Thi Loan Mai, Hyeon Kyu Yoon, J. Ryu, Wonhee Lee, Pyungmo Ku
: A submerged body with varied control inputs can execute large drift angles and large angles of attack, as well as basic control such as straight movement and turning. The objective of this study is to analyze the dynamic characteristics of a submerged body comprising six thrusters and six control planes, which is capable of a large drift angle and angle of attack motion. Virtual captive model tests via were analyzed via computational fluid dynamics (CFD) to determine the dynamic characteristics of the submerged body. A test matrix of virtual captive model tests specialized for large-angle motion was established. Based on this test matrix, virtual captive model tests were performed with a drift angle and angle of attack of approximately 30° and 90°, respectively. The characteristics of the hydrodynamic force acting on the horizontal and vertical surfaces of the submerged body were analyzed under the large-angle motion condition, and a model representing this hydrodynamic force was established. In addition, maneuvering simulation was performed to evaluate the standard maneuverability and dynamic characteristics of large-angle motion. Considering the shape characteristics of the submerged body, we attempt to verify the feasibility of the analysis results by analyzing the characteristics of the hydrodynamic force when the large-angle motion occurred.
{"title":"Evaluation of Dynamic Characteristics for a Submerged Body with Large Angle of Attack Motion via CFD Analysis","authors":"Myungjun Jeon, Thi Loan Mai, Hyeon Kyu Yoon, J. Ryu, Wonhee Lee, Pyungmo Ku","doi":"10.26748/ksoe.2021.063","DOIUrl":"https://doi.org/10.26748/ksoe.2021.063","url":null,"abstract":": A submerged body with varied control inputs can execute large drift angles and large angles of attack, as well as basic control such as straight movement and turning. The objective of this study is to analyze the dynamic characteristics of a submerged body comprising six thrusters and six control planes, which is capable of a large drift angle and angle of attack motion. Virtual captive model tests via were analyzed via computational fluid dynamics (CFD) to determine the dynamic characteristics of the submerged body. A test matrix of virtual captive model tests specialized for large-angle motion was established. Based on this test matrix, virtual captive model tests were performed with a drift angle and angle of attack of approximately 30° and 90°, respectively. The characteristics of the hydrodynamic force acting on the horizontal and vertical surfaces of the submerged body were analyzed under the large-angle motion condition, and a model representing this hydrodynamic force was established. In addition, maneuvering simulation was performed to evaluate the standard maneuverability and dynamic characteristics of large-angle motion. Considering the shape characteristics of the submerged body, we attempt to verify the feasibility of the analysis results by analyzing the characteristics of the hydrodynamic force when the large-angle motion occurred.","PeriodicalId":315103,"journal":{"name":"Journal of Ocean Engineering and Technology","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114066312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper describes a recurrent neural network (RNN) for the fault classification of a blade pitch system of a spar-type floating wind turbine. An artificial neural network (ANN) can effectively recognize multiple faults of a system and build a training model with training data for decision-making. The ANN comprises an encoder and a decoder. The encoder uses a gated recurrent unit, which is a recurrent neural network, for dimensionality reduction of the input data. The decoder uses a multilayer perceptron (MLP) for diagnosis decision-making. To create data, we use a wind turbine simulator that enables fully coupled nonlinear time-domain numerical simulations of offshore wind turbines considering six fault types including biases and fixed outputs in pitch sensors and excessive friction, slit lock, incorrect voltage, and short circuits in actuators. The input data are time-series data collected by two sensors and two control inputs under the condition that of one fault of the six types occurs. A gated recurrent unit (GRU) that is one of the RNNs classifies the suggested faults of the blade pitch system. The performance of fault classification based on the gate recurrent unit is evaluated by a test procedure, and the results indicate that the proposed scheme works effectively. The proposed ANN shows a 1.4% improvement in its performance compared to an MLP-based approach.
{"title":"Fault Classification of a Blade Pitch System in a Floating Wind Turbine Based on a Recurrent Neural Network","authors":"Seongpil Cho, J. Park, Minjoo Choi","doi":"10.26748/ksoe.2021.018","DOIUrl":"https://doi.org/10.26748/ksoe.2021.018","url":null,"abstract":"This paper describes a recurrent neural network (RNN) for the fault classification of a blade pitch system of a spar-type floating wind turbine. An artificial neural network (ANN) can effectively recognize multiple faults of a system and build a training model with training data for decision-making. The ANN comprises an encoder and a decoder. The encoder uses a gated recurrent unit, which is a recurrent neural network, for dimensionality reduction of the input data. The decoder uses a multilayer perceptron (MLP) for diagnosis decision-making. To create data, we use a wind turbine simulator that enables fully coupled nonlinear time-domain numerical simulations of offshore wind turbines considering six fault types including biases and fixed outputs in pitch sensors and excessive friction, slit lock, incorrect voltage, and short circuits in actuators. The input data are time-series data collected by two sensors and two control inputs under the condition that of one fault of the six types occurs. A gated recurrent unit (GRU) that is one of the RNNs classifies the suggested faults of the blade pitch system. The performance of fault classification based on the gate recurrent unit is evaluated by a test procedure, and the results indicate that the proposed scheme works effectively. The proposed ANN shows a 1.4% improvement in its performance compared to an MLP-based approach.","PeriodicalId":315103,"journal":{"name":"Journal of Ocean Engineering and Technology","volume":"108 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134372752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the present study, the performance of a floating oscillating water column (OWC) device has been studied in regular waves. The OWC model has the shape of a hollow cylinder. The linear potential theory is assumed, and a matched eigenfunction expansion method(MEEM) is applied for solving the diffraction and radiation problems. The radiation problem involves the radiation of waves by the heaving motion of a floating OWC device and the oscillating pressure in the air chamber. The characteristics of the exciting forces, hydrodynamic forces, flow rate, air pressure in the chamber, and heave motion response are investigated with various system parameters, such as the inner radius, draft of an OWC, and turbine constant. The efficiency of a floating OWC device is estimated in connection with the extracted wave power and capture width. Specifically, the piston-mode resonance in an internal fluid region plays an important role in the performance of a floating OWC device, along with the heave motion resonance. The developed prediction tool will help determine the various design parameters affecting the performance of a floating OWC device in waves. Received 3 February 2021, revised 15 March 2021, accepted 14 April 2021 Corresponding author Il Hyoung Cho: +82-64-754-3482, cho0904@jejunu.ac.kr c 2021, The Korean Society of Ocean Engineers This is an open access article distributed under the terms of the creative commons attribution non-commercial license (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
本文研究了浮动振荡水柱(OWC)装置在规则波中的性能。OWC模型具有中空圆柱体的形状。假设线性势理论，采用匹配特征函数展开法求解衍射和辐射问题。辐射问题涉及到浮式OWC装置的起伏运动和气室内的振荡压力所产生的波的辐射。研究了激励力、水动力、流量、室内气压和升沉运动响应在不同系统参数下的特性，如OWC内半径、OWC的牵伸和涡轮常数。根据提取的波浪能和捕获宽度估算了浮动OWC装置的效率。具体而言，内部流体区域的活塞型共振与升沉运动共振对浮式OWC装置的性能起着重要作用。开发的预测工具将有助于确定影响浮动OWC装置在波浪中的性能的各种设计参数。通讯作者Il Hyoung Cho: +82-64-754-3482, cho0904@jejunu.ac.kr c 2021, The Korean Society of Ocean Engineers这是一篇开放获取的文章，根据创作共用署名非商业许可(http://creativecommons.org/licenses/by-nc/4.0)的条款分发，允许不受限制的非商业使用、分发和在任何媒介上复制，前提是原始作品被适当引用。
{"title":"Effect of Internal Fluid Resonance on the Performance of a Floating OWC Device","authors":"I. Cho","doi":"10.26748/KSOE.2021.011","DOIUrl":"https://doi.org/10.26748/KSOE.2021.011","url":null,"abstract":"In the present study, the performance of a floating oscillating water column (OWC) device has been studied in regular waves. The OWC model has the shape of a hollow cylinder. The linear potential theory is assumed, and a matched eigenfunction expansion method(MEEM) is applied for solving the diffraction and radiation problems. The radiation problem involves the radiation of waves by the heaving motion of a floating OWC device and the oscillating pressure in the air chamber. The characteristics of the exciting forces, hydrodynamic forces, flow rate, air pressure in the chamber, and heave motion response are investigated with various system parameters, such as the inner radius, draft of an OWC, and turbine constant. The efficiency of a floating OWC device is estimated in connection with the extracted wave power and capture width. Specifically, the piston-mode resonance in an internal fluid region plays an important role in the performance of a floating OWC device, along with the heave motion resonance. The developed prediction tool will help determine the various design parameters affecting the performance of a floating OWC device in waves. Received 3 February 2021, revised 15 March 2021, accepted 14 April 2021 Corresponding author Il Hyoung Cho: +82-64-754-3482, cho0904@jejunu.ac.kr c 2021, The Korean Society of Ocean Engineers This is an open access article distributed under the terms of the creative commons attribution non-commercial license (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.","PeriodicalId":315103,"journal":{"name":"Journal of Ocean Engineering and Technology","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114961751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Nguyen, Thi Thanh Diep Nguyen, H. Yoon, Y. H. Kim
The maneuvering performance of a ship on the actual sea is very different from that in calm water due to wave-induced motion. Enhancement of a ship’s maneuverability in waves at the design stage is an important way to ensure that the ship navigates safely. This paper focuses on the maneuvering prediction of a Russian trawler in wind and irregular waves. First, a unified seakeeping and maneuvering analysis of a Russian trawler is proposed. The hydrodynamic forces acting on the hull in calm water were estimated using empirical formulas based on a database containing information on several fishing vessels. A simulation of the standard maneuvering of the Russian trawler was conducted in calm water, which was checked using the International Maritime Organization (IMO) standards for ship maneuvering. Second, a unified model of seakeeping and maneuvering that considers the effect of wind and waves is proposed. The wave forces were estimated by a three-dimensional (3D) panel program (ANSYS-AQWA) and used as a database when simulating the ship maneuvering in wind and irregular waves. The wind forces and moments acting on the Russian trawler are estimated using empirical formulas based on a database of wind-tunnel test results. Third, standard maneuvering of a Russian trawler was conducted in various directions under wind and irregular wave conditions. Finally, the influence of wind and wave directions on the drifting distance and drifting angle of the ship as it turns in a circle was found. North wind has a dominant influence on the turning trajectory of the trawler. Received 15 December 2020, revised 2 March 2021, accepted 2 May 2021 Corresponding author Hyeon Kyu Yoon: +82-55-213-3683, hkyoon@changwon.ac.kr This paper was presented on the subject of “Numerical Study on Unified Seakeeping and Maneuvering of a Russian Trawler in Wind and Wave” in the proceedings of 2020 Korean Society of Ocean Engineers Fall Conference. c 2021, The Korean Society of Ocean Engineers This is an open access article distributed under the terms of the creative commons attribution non-commercial license (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
由于波浪引起的运动，船舶在实际海面上的操纵性能与在平静水域中的操纵性能大不相同。在设计阶段提高船舶在波浪中的操纵性是确保船舶安全航行的重要途径。本文重点研究了一艘俄罗斯拖网渔船在风浪和不规则波浪中的操纵预测。首先，提出了俄罗斯拖网渔船的统一适航性和操纵性分析方法。根据包含多艘渔船信息的数据库，使用经验公式估算了平静水域中作用在船体上的流体动力。对俄罗斯拖网渔船在平静水域的标准操纵进行了模拟，并使用国际海事组织（IMO）的船舶操纵标准进行了检查。其次，提出了一个考虑风浪影响的海上航行和操纵统一模型。波浪力由三维（3D）面板程序（ANSYS-AQWA）估算，并在模拟船舶在风浪和不规则波浪中的操纵时用作数据库。作用在俄罗斯拖网渔船上的风力和风矩是通过基于风洞试验结果数据库的经验公式估算的。第三，在风和不规则波浪条件下，俄罗斯拖网渔船在不同方向上进行了标准操纵。最后，研究了风向和波向对拖网渔船转圈时漂移距离和漂移角度的影响。北风对拖网渔船的转向轨迹有主要影响。2020 年 12 月 15 日收到，2021 年 3 月 2 日修订，2021 年 5 月 2 日接受 通讯作者 Hyeon Kyu Yoon：+82-55-213-3683, hkyoon@changwon.ac.kr 本文以 "俄罗斯拖网渔船在风浪中的统一海上航行和操纵的数值研究 "为题，发表于 2020 年韩国海洋工程师学会秋季会议论文集。c 2021, The Korean Society of Ocean Engineers 本文为开放存取文章，根据创作共用非商业性许可 (http://creativecommons.org/licenses/by-nc/4.0) 条款发布，允许在任何媒体上进行不受限制的非商业性使用、分发和复制，但须适当引用原作。
{"title":"Numerical Study on Unified Seakeeping and Maneuvering of a Russian Trawler in Wind and Waves","authors":"V. Nguyen, Thi Thanh Diep Nguyen, H. Yoon, Y. H. Kim","doi":"10.26748/KSOE.2020.075","DOIUrl":"https://doi.org/10.26748/KSOE.2020.075","url":null,"abstract":"The maneuvering performance of a ship on the actual sea is very different from that in calm water due to wave-induced motion. Enhancement of a ship’s maneuverability in waves at the design stage is an important way to ensure that the ship navigates safely. This paper focuses on the maneuvering prediction of a Russian trawler in wind and irregular waves. First, a unified seakeeping and maneuvering analysis of a Russian trawler is proposed. The hydrodynamic forces acting on the hull in calm water were estimated using empirical formulas based on a database containing information on several fishing vessels. A simulation of the standard maneuvering of the Russian trawler was conducted in calm water, which was checked using the International Maritime Organization (IMO) standards for ship maneuvering. Second, a unified model of seakeeping and maneuvering that considers the effect of wind and waves is proposed. The wave forces were estimated by a three-dimensional (3D) panel program (ANSYS-AQWA) and used as a database when simulating the ship maneuvering in wind and irregular waves. The wind forces and moments acting on the Russian trawler are estimated using empirical formulas based on a database of wind-tunnel test results. Third, standard maneuvering of a Russian trawler was conducted in various directions under wind and irregular wave conditions. Finally, the influence of wind and wave directions on the drifting distance and drifting angle of the ship as it turns in a circle was found. North wind has a dominant influence on the turning trajectory of the trawler. Received 15 December 2020, revised 2 March 2021, accepted 2 May 2021 Corresponding author Hyeon Kyu Yoon: +82-55-213-3683, hkyoon@changwon.ac.kr This paper was presented on the subject of “Numerical Study on Unified Seakeeping and Maneuvering of a Russian Trawler in Wind and Wave” in the proceedings of 2020 Korean Society of Ocean Engineers Fall Conference. c 2021, The Korean Society of Ocean Engineers This is an open access article distributed under the terms of the creative commons attribution non-commercial license (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.","PeriodicalId":315103,"journal":{"name":"Journal of Ocean Engineering and Technology","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129944295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sunny Kumar Poguluri, Dongeun Kim, H. Ko, Y. H. Bae
A numerical hydrodynamic performance analysis of the pitch-type multibody wave energy converter (WEC) is carried out based on both linear potential flow theory and computational fluid dynamics (CFD) in the unidirectional wave condition. In the present study, Salter's duck (rotor) is chosen for the analysis. The basic concept of the WEC rotor, which nods when the pressure-induced motions are in phase, is that it converts the kinetic and potential energies of the wave into rotational mechanical energy with the proper power-take-off system. This energy is converted to useful electric energy. The analysis is carried out using three WEC rotors. A multibody analysis using linear potential flow theory is performed using WAMIT (three-dimensional diffraction/radiation potential analysis program), and a CFD analysis is performed by placing three WEC rotors in a numerical wave tank. In particular, the spacing between the three rotors is set to 0.8, 1, and 1.2 times the rotor width, and the hydrodynamic interaction between adjacent rotors is checked. Finally, it is confirmed that the dynamic performance of the rotors slightly changes, but the difference due to the spacing is not noticeable. In addition, the CFD analysis shows a lateral flow phenomenon that cannot be confirmed by linear potential theory, and it is confirmed that the CFD analysis is necessary for the motion analysis of the rotor. Received 19 January 2021, revised 6 May 2021, accepted 7 May 2021 Corresponding author Yoon Hyeok Bae: +82-64-754-3485, yh.bae@jejunu.ac.kr c 2021, The Korean Society of Ocean Engineers This is an open access article distributed under the terms of the creative commons attribution non-commercial license (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
基于线性势流理论和计算流体力学理论，对螺距型多体波能转换器(WEC)在单向波动条件下的水动力性能进行了数值分析。在本研究中，选择索尔特鸭(转子)进行分析。WEC转子在压力引起的运动相同时发生节点，其基本概念是通过适当的动力输出系统将波浪的动能和势能转化为旋转机械能。这种能量被转化为有用的电能。分析是使用三个WEC转子进行的。利用WAMIT(三维衍射/辐射势分析程序)进行了基于线性势流理论的多体分析，并通过在数值波槽中放置三个WEC转子进行了CFD分析。其中，三个转子之间的间距分别设置为转子宽度的0.8倍、1倍和1.2倍，并检查相邻转子之间的流体动力相互作用。最后，证实了转子的动态性能略有变化，但由于间距的差异并不明显。此外，CFD分析显示了一种线性势理论无法证实的横向流动现象，证实了CFD分析对转子运动分析的必要性。通讯作者Yoon Hyeok Bae: +82-64-754-3485, yh.bae@jejunu.ac.kr c 2021, The Korean Society of Ocean Engineers这是一篇开放获取的文章，根据创作共用署名非商业许可(http://creativecommons.org/licenses/by-nc/4.0)的条款分发，该许可允许不受限制的非商业使用，分发和复制在任何媒介上，只要原始作品被适当引用。
{"title":"Performance Analysis of Multiple Wave Energy Converters due to Rotor Spacing","authors":"Sunny Kumar Poguluri, Dongeun Kim, H. Ko, Y. H. Bae","doi":"10.26748/KSOE.2021.007","DOIUrl":"https://doi.org/10.26748/KSOE.2021.007","url":null,"abstract":"A numerical hydrodynamic performance analysis of the pitch-type multibody wave energy converter (WEC) is carried out based on both linear potential flow theory and computational fluid dynamics (CFD) in the unidirectional wave condition. In the present study, Salter's duck (rotor) is chosen for the analysis. The basic concept of the WEC rotor, which nods when the pressure-induced motions are in phase, is that it converts the kinetic and potential energies of the wave into rotational mechanical energy with the proper power-take-off system. This energy is converted to useful electric energy. The analysis is carried out using three WEC rotors. A multibody analysis using linear potential flow theory is performed using WAMIT (three-dimensional diffraction/radiation potential analysis program), and a CFD analysis is performed by placing three WEC rotors in a numerical wave tank. In particular, the spacing between the three rotors is set to 0.8, 1, and 1.2 times the rotor width, and the hydrodynamic interaction between adjacent rotors is checked. Finally, it is confirmed that the dynamic performance of the rotors slightly changes, but the difference due to the spacing is not noticeable. In addition, the CFD analysis shows a lateral flow phenomenon that cannot be confirmed by linear potential theory, and it is confirmed that the CFD analysis is necessary for the motion analysis of the rotor. Received 19 January 2021, revised 6 May 2021, accepted 7 May 2021 Corresponding author Yoon Hyeok Bae: +82-64-754-3485, yh.bae@jejunu.ac.kr c 2021, The Korean Society of Ocean Engineers This is an open access article distributed under the terms of the creative commons attribution non-commercial license (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.","PeriodicalId":315103,"journal":{"name":"Journal of Ocean Engineering and Technology","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121674223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sung-min Park, C. Lee, Daekyeong Kong, Kwang-il Hwang, D. Doh, G. Cho
Tomographic particle image velocimetry (PIV) is a widely used method that measures a three-dimensional (3D) flow field by reconstructing camera images into voxel images. In 3D measurements, the setting and calibration of the camera's mapping function significantly impact the obtained results. In this study, a camera self-calibration technique is applied to tomographic PIV to reduce the occurrence of errors arising from such functions. The measured 3D particles are superimposed on the image to create a disparity map. Camera self-calibration is performed by reflecting the error of the disparity map to the center value of the particles. Vortex ring synthetic images are generated and the developed algorithm is applied. The optimal result is obtained by applying self-calibration once when the center error is less than 1 pixel and by applying self-calibration 2–3 times when it was more than 1 pixel; the maximum recovery ratio is 96%. Further self-correlation did not improve the results. The algorithm is evaluated by performing an actual rotational flow experiment, and the optimal result was obtained when self-calibration was applied once, as shown in the virtual image result. Therefore, the developed algorithm is expected to be utilized for the performance improvement of 3D flow measurements. Received 12 January 2021, revised 20 April 2021, accepted 12 May 2021 Corresponding author Gyeong-Rae Cho: +82-51-410-4957, v_pascal@daum.net c 2021, The Korean Society of Ocean Engineers This is an open access article distributed under the terms of the creative commons attribution non-commercial license (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
层析粒子图像测速(PIV)是一种广泛应用的测量三维流场的方法，它将相机图像重构为体素图像。在三维测量中，相机映射功能的设置和校准对获得的结果有很大影响。本研究将摄像机自标定技术应用于层析PIV，以减少此类功能产生的误差。测量的3D粒子叠加在图像上，形成视差图。摄像机通过将视差图的误差反映到粒子的中心值来进行自标定。生成了涡环合成图像，并应用了该算法。当中心误差小于1像素时，自校准1次;当中心误差大于1像素时，自校准2-3次，获得最优结果;最大回收率为96%。进一步的自相关并没有改善结果。通过实际旋转流实验对该算法进行了评价，结果表明，自标定一次即可获得最优结果，如虚拟图像结果所示。因此，所开发的算法有望用于提高三维流量测量的性能。通讯作者gung - rae Cho: +82-51-410-4957, v_pascal@daum.net c 2021, The Korean Society of Ocean Engineers这是一篇开放获取的文章，根据创作共用归属非商业许可(http://creativecommons.org/licenses/by-nc/4.0)的条款分发，允许不受限制的非商业使用，分发，以及在任何媒介上复制，只要原始作品被适当引用。
{"title":"Development of a Camera Self-calibration Method for 10-parameter Mapping Function","authors":"Sung-min Park, C. Lee, Daekyeong Kong, Kwang-il Hwang, D. Doh, G. Cho","doi":"10.26748/KSOE.2021.005","DOIUrl":"https://doi.org/10.26748/KSOE.2021.005","url":null,"abstract":"Tomographic particle image velocimetry (PIV) is a widely used method that measures a three-dimensional (3D) flow field by reconstructing camera images into voxel images. In 3D measurements, the setting and calibration of the camera's mapping function significantly impact the obtained results. In this study, a camera self-calibration technique is applied to tomographic PIV to reduce the occurrence of errors arising from such functions. The measured 3D particles are superimposed on the image to create a disparity map. Camera self-calibration is performed by reflecting the error of the disparity map to the center value of the particles. Vortex ring synthetic images are generated and the developed algorithm is applied. The optimal result is obtained by applying self-calibration once when the center error is less than 1 pixel and by applying self-calibration 2–3 times when it was more than 1 pixel; the maximum recovery ratio is 96%. Further self-correlation did not improve the results. The algorithm is evaluated by performing an actual rotational flow experiment, and the optimal result was obtained when self-calibration was applied once, as shown in the virtual image result. Therefore, the developed algorithm is expected to be utilized for the performance improvement of 3D flow measurements. Received 12 January 2021, revised 20 April 2021, accepted 12 May 2021 Corresponding author Gyeong-Rae Cho: +82-51-410-4957, v_pascal@daum.net c 2021, The Korean Society of Ocean Engineers This is an open access article distributed under the terms of the creative commons attribution non-commercial license (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.","PeriodicalId":315103,"journal":{"name":"Journal of Ocean Engineering and Technology","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121147700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Current industrial practices and approaches are simplified and do not describe the actual behavior of plated elements of offshore topside structures for safety design due to fires. Therefore, it is better to make up for the defective methods with integrated fire safety design methods based on fire resistance characteristics such as residual strength capacity. This study numerically investigates the residual strength of steel stiffened panels exposed to hydrocarbon jet fire. A series of nonlinear finite element analyses (FEAs) were carried out with varying probabilistic selected exposures in terms of the jet fire location, side, area, and duration. These were used to assess the effects of exposed fire on the residual strength of a steel stiffened panel on a ship-shaped offshore structure. A probabilistic approach with a feasible fire location was used to determine credible fire scenarios in association with thermal structural responses. Heat transfer analysis was performed to obtain the steel temperature, and then the residual strength was obtained for the credible fire scenarios under compressive axial loading using nonlinear FEA code. The results were used to derive closed-form expressions to predict the residual strength of steel stiffened panels with various exposure to jet fire characteristics. The results could be used to assess the sustainability of structures at risk of exposure to fire accidents in offshore installations. Received 19 January 2021, revised 15 May 2021, accepted 31 May 2021 Corresponding author Jung Kwan Seo: +82-51-510-2415, seojk@pusan.ac.kr It is noted that this paper is revised edition based on proceedings of the Annual Autumn Conference of KSOE 2018 in Incheon. c 2021, The Korean Society of Ocean Engineers This is an open access article distributed under the terms of the creative commons attribution non-commercial license (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
{"title":"Numerical Investigation of Residual Strength of Steel Stiffened Panel Exposed to Hydrocarbon Fire","authors":"Jeong Hwan Kim, Daesung Baeg, J. Seo","doi":"10.26748/ksoe.2021.008","DOIUrl":"https://doi.org/10.26748/ksoe.2021.008","url":null,"abstract":"Current industrial practices and approaches are simplified and do not describe the actual behavior of plated elements of offshore topside structures for safety design due to fires. Therefore, it is better to make up for the defective methods with integrated fire safety design methods based on fire resistance characteristics such as residual strength capacity. This study numerically investigates the residual strength of steel stiffened panels exposed to hydrocarbon jet fire. A series of nonlinear finite element analyses (FEAs) were carried out with varying probabilistic selected exposures in terms of the jet fire location, side, area, and duration. These were used to assess the effects of exposed fire on the residual strength of a steel stiffened panel on a ship-shaped offshore structure. A probabilistic approach with a feasible fire location was used to determine credible fire scenarios in association with thermal structural responses. Heat transfer analysis was performed to obtain the steel temperature, and then the residual strength was obtained for the credible fire scenarios under compressive axial loading using nonlinear FEA code. The results were used to derive closed-form expressions to predict the residual strength of steel stiffened panels with various exposure to jet fire characteristics. The results could be used to assess the sustainability of structures at risk of exposure to fire accidents in offshore installations. Received 19 January 2021, revised 15 May 2021, accepted 31 May 2021 Corresponding author Jung Kwan Seo: +82-51-510-2415, seojk@pusan.ac.kr It is noted that this paper is revised edition based on proceedings of the Annual Autumn Conference of KSOE 2018 in Incheon. c 2021, The Korean Society of Ocean Engineers This is an open access article distributed under the terms of the creative commons attribution non-commercial license (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.","PeriodicalId":315103,"journal":{"name":"Journal of Ocean Engineering and Technology","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132620445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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