Pub Date : 2010-08-31DOI: 10.3796/KSFT.2010.46.3.195
S. Kim, Chang–Doo Park, Seong-wook Park, Jong-Keun Shin
Recently, Fishermen have required to expand the circumference of trap entrance for conger eel because it wasdifficult to take the catch out as well as to put the baits into. A series of fishing experiments was carried out incoastal areas of Tongyoung, Korea in 2008 and 2009 using the traps to describe the effect of the entrance size onthe catch. The experimental traps (five types) were used in filed experiments with four types circumference sizetraps (140, 180, 220 and 260mm) with mesh size 22mm and another type was used the same one usually using infiled with mesh size 35mm (750mm circumference). The experiment results were, the conger eels of total length35mm more or so were caught 85, 93, 142 and 176 individual by the experiment traps with mesh size 22mm asincrease circumference size from 140mm to 260mm, respectively. And the small conger eels of the total lengthbelow 35mm to be prohibited to catch by law were caught 145, 160, 288 and 304 individual according toincrease the circumference size of trap, respectively. In addition, in case of the trap with mesh size 22mm,bycatches were 230260 individuals and much more than bycatches of the trap with mesh size 35mm. Inconclusion, when we expand the circumference size of trap according to fishermens requirement, we shouldreview not only economic of fishery but also increasement the bycatch of non-target fishes and small size fishes.Keywords: Bycatch, Conger eel, Entrance size, Selectivity, Trap
{"title":"The effect of the entrance size on the catch of trap for conger eel","authors":"S. Kim, Chang–Doo Park, Seong-wook Park, Jong-Keun Shin","doi":"10.3796/KSFT.2010.46.3.195","DOIUrl":"https://doi.org/10.3796/KSFT.2010.46.3.195","url":null,"abstract":"Recently, Fishermen have required to expand the circumference of trap entrance for conger eel because it wasdifficult to take the catch out as well as to put the baits into. A series of fishing experiments was carried out incoastal areas of Tongyoung, Korea in 2008 and 2009 using the traps to describe the effect of the entrance size onthe catch. The experimental traps (five types) were used in filed experiments with four types circumference sizetraps (140, 180, 220 and 260mm) with mesh size 22mm and another type was used the same one usually using infiled with mesh size 35mm (750mm circumference). The experiment results were, the conger eels of total length35mm more or so were caught 85, 93, 142 and 176 individual by the experiment traps with mesh size 22mm asincrease circumference size from 140mm to 260mm, respectively. And the small conger eels of the total lengthbelow 35mm to be prohibited to catch by law were caught 145, 160, 288 and 304 individual according toincrease the circumference size of trap, respectively. In addition, in case of the trap with mesh size 22mm,bycatches were 230260 individuals and much more than bycatches of the trap with mesh size 35mm. Inconclusion, when we expand the circumference size of trap according to fishermens requirement, we shouldreview not only economic of fishery but also increasement the bycatch of non-target fishes and small size fishes.Keywords: Bycatch, Conger eel, Entrance size, Selectivity, Trap","PeriodicalId":211073,"journal":{"name":"Bulletin of The Korean Society of Fisheries Technology","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133129479","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}
Pub Date : 2010-08-31DOI: 10.3796/KSFT.2010.46.3.257
Seong-wook Park, S. Kim, H. Choi, H. Cho
In order to improve the breaking strength and elongation of Polybutylene succinate (PBS) monofilament, themonofilament was produced by blending PBS and Polybutlyne adipate-co-terephthalate (PBAT). ThePBS/PBAT blend monofilament was prepared by the melt spinning system, and the weight ratios of thecompositions of PBS/PBAT was 100/0, 95/5, 90/10 and 85/15, respectively. The breaking strength,elongation, softness and crystallization of PBS/PBAT blend monofilament were analyzed by using atensionmeter, softness measurement, X-ray diffractometer in the both dry and wet conditions. ThePBS/PBAT blend monofilaments were spun in the take-up velocity of 1.19m/sec under the drawing ratio of6.8:1 condition. The production volumes of PBS/PBAT blend monofilaments showed 20% less than that ofNylon. The breaking strength of PBS/PBAT blend monofilaments were decreased as PBAT contentsincreased, while elongation and softness were increased. In case of PBAT content were over 5%, thebreaking strength, elongation and softness of PBS/PBAT blend monofilaments were not shown to increasein spite of increasing in PBAT contents. Based on these results, it was possible to make the monofilamentswith the maximized physical properties when the PBAT contents at 5%.Keywords: Biodegradation, Polybutylene succinate, Monofilament, Physical properties
{"title":"Preparation and physical properties of biodegradable polybutylene succinate/polybutylene adipate-co-terephthalate blend monofilament by melt spinning","authors":"Seong-wook Park, S. Kim, H. Choi, H. Cho","doi":"10.3796/KSFT.2010.46.3.257","DOIUrl":"https://doi.org/10.3796/KSFT.2010.46.3.257","url":null,"abstract":"In order to improve the breaking strength and elongation of Polybutylene succinate (PBS) monofilament, themonofilament was produced by blending PBS and Polybutlyne adipate-co-terephthalate (PBAT). ThePBS/PBAT blend monofilament was prepared by the melt spinning system, and the weight ratios of thecompositions of PBS/PBAT was 100/0, 95/5, 90/10 and 85/15, respectively. The breaking strength,elongation, softness and crystallization of PBS/PBAT blend monofilament were analyzed by using atensionmeter, softness measurement, X-ray diffractometer in the both dry and wet conditions. ThePBS/PBAT blend monofilaments were spun in the take-up velocity of 1.19m/sec under the drawing ratio of6.8:1 condition. The production volumes of PBS/PBAT blend monofilaments showed 20% less than that ofNylon. The breaking strength of PBS/PBAT blend monofilaments were decreased as PBAT contentsincreased, while elongation and softness were increased. In case of PBAT content were over 5%, thebreaking strength, elongation and softness of PBS/PBAT blend monofilaments were not shown to increasein spite of increasing in PBAT contents. Based on these results, it was possible to make the monofilamentswith the maximized physical properties when the PBAT contents at 5%.Keywords: Biodegradation, Polybutylene succinate, Monofilament, Physical properties","PeriodicalId":211073,"journal":{"name":"Bulletin of The Korean Society of Fisheries Technology","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114569598","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}
Pub Date : 2010-08-31DOI: 10.3796/KSFT.2010.46.3.214
Jihoon Lee, Chun-woo Lee, L. Karlsen
The paper presents investigations on to which degree the sinking speed of longlines is influenced by type ofbait, bait sinking orientations and anchor weights. The main aim of this study is to obtain further insight inthe ocean current displacement phenomena in demersal longlining. The sinking speed is one of the mainfactors deciding the current displacement. In an ongoing project, sinking speed experiments with longlineswith 6 kg and 10 kg anchor weights have been carried out in the Trondheim fjord. The longlines used in thefirst experiments were rigged without bait and hook. The results of these experiments with two differentanchor weights have revealed only a slight difference in the sinking speed, except for the part near to theanchors, even though the sinking speed of longlines in general is supposed to be much influenced by theanchor weights. The reason for the obtained result is supposed to be that the experiments have been carriedout at relative shallow waters. Further studies have included bait sinking experiments in the flume tank. Theexperiments showed that the drag coefficient of fillet type (flat)bait varied from 0.763 to 1.735, while itfor elliptic typebait varied from 0.62 to 1.483. Other activities have included calculation of the sinkingspeed of longlines as a function of the established resistance coefficients of bait of various shape and size forcommercial longlining. The calculated sinking speed of a longline with the fillet type bait was found to be12.4 to 16.5% lower than for a longline without bait. Keywords: Sinking speed of longlines, Baits, Anchor weights, Numerical methods, Ocean currentdisplacement of longlines
{"title":"A study of the sinking speed of longlines influenced by bait properties and anchor weights","authors":"Jihoon Lee, Chun-woo Lee, L. Karlsen","doi":"10.3796/KSFT.2010.46.3.214","DOIUrl":"https://doi.org/10.3796/KSFT.2010.46.3.214","url":null,"abstract":"The paper presents investigations on to which degree the sinking speed of longlines is influenced by type ofbait, bait sinking orientations and anchor weights. The main aim of this study is to obtain further insight inthe ocean current displacement phenomena in demersal longlining. The sinking speed is one of the mainfactors deciding the current displacement. In an ongoing project, sinking speed experiments with longlineswith 6 kg and 10 kg anchor weights have been carried out in the Trondheim fjord. The longlines used in thefirst experiments were rigged without bait and hook. The results of these experiments with two differentanchor weights have revealed only a slight difference in the sinking speed, except for the part near to theanchors, even though the sinking speed of longlines in general is supposed to be much influenced by theanchor weights. The reason for the obtained result is supposed to be that the experiments have been carriedout at relative shallow waters. Further studies have included bait sinking experiments in the flume tank. Theexperiments showed that the drag coefficient of fillet type (flat)bait varied from 0.763 to 1.735, while itfor elliptic typebait varied from 0.62 to 1.483. Other activities have included calculation of the sinkingspeed of longlines as a function of the established resistance coefficients of bait of various shape and size forcommercial longlining. The calculated sinking speed of a longline with the fillet type bait was found to be12.4 to 16.5% lower than for a longline without bait. Keywords: Sinking speed of longlines, Baits, Anchor weights, Numerical methods, Ocean currentdisplacement of longlines","PeriodicalId":211073,"journal":{"name":"Bulletin of The Korean Society of Fisheries Technology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134102813","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}
Pub Date : 2010-08-31DOI: 10.3796/KSFT.2010.46.3.223
Hae-Hoon Park, R. Millar, Bong-Seong Bae, Heui–Chun An, Seon-Jae Hwang
This paper showed the difference between the selectivity of gill net by least square method with polynomials inKitahara s and that by maximum likelihood analysis for Japanese sandfish and Korean flounder. Catchexperiments for Japanese sandfish using commercial vessels off the eastern coast of Korea were conductedwith six different mesh sizes between October and December 2007 and those for Korean flounder with fivedifferent mesh sizes between 2008 and 2009. The mesh size of 50% probability of catch corresponding tobiological maturity length of fish was not different between that by least square method and that by maximumlikelihood analysis for Japanese sandfish, however, a little different for Korean flounder, that is, those meshsizes of 50% probability of catch for biological maturity length of Korean flounder were 10.6cm and 10.1cmby least square method and maximum likelihood analysis, respectively.Keywords: Selectivity, Gill net, Kitaharas method, Least square method, Maximum likelihood analysis,Japanese sandfish, Korean flounder
{"title":"The difference of selectivity of gill net between least square method with polynomials in Kitahara s and maximum likelihood analysis","authors":"Hae-Hoon Park, R. Millar, Bong-Seong Bae, Heui–Chun An, Seon-Jae Hwang","doi":"10.3796/KSFT.2010.46.3.223","DOIUrl":"https://doi.org/10.3796/KSFT.2010.46.3.223","url":null,"abstract":"This paper showed the difference between the selectivity of gill net by least square method with polynomials inKitahara s and that by maximum likelihood analysis for Japanese sandfish and Korean flounder. Catchexperiments for Japanese sandfish using commercial vessels off the eastern coast of Korea were conductedwith six different mesh sizes between October and December 2007 and those for Korean flounder with fivedifferent mesh sizes between 2008 and 2009. The mesh size of 50% probability of catch corresponding tobiological maturity length of fish was not different between that by least square method and that by maximumlikelihood analysis for Japanese sandfish, however, a little different for Korean flounder, that is, those meshsizes of 50% probability of catch for biological maturity length of Korean flounder were 10.6cm and 10.1cmby least square method and maximum likelihood analysis, respectively.Keywords: Selectivity, Gill net, Kitaharas method, Least square method, Maximum likelihood analysis,Japanese sandfish, Korean flounder","PeriodicalId":211073,"journal":{"name":"Bulletin of The Korean Society of Fisheries Technology","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127343868","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}
Pub Date : 2010-05-31DOI: 10.3796/KSFT.2010.46.2.126
Jae Bong Lee, Jong Hee Lee, Y. Shin, C. Zhang, H. Cha
To investigate seasonal variation of fisheries resources composition and their correlationships withenvironmental facotrs in the coastal ecosystem of the middle Yellow Sea of Korea, shrimp beam trawl werecarried out for the fisheries survey. Fisheries resources of 81 species, 57 families, and 6 taxa totally werecollected by shrimp beam trawl in the middle coastal ecosystem of Yellow Sea of Korea. Species were included6 species in Bivalvia, 6 in Cephalopoda, 22 in Crustacea, 2 in Echinodermata, 5 in Gastropoda, and 40 in Pisces.Diversity indices (Shannon index, H) showed seasonal variation with low value of 2.14 in winter, and highvalue of 2.67 in spring. Main dominant species were
{"title":"Seasonal variation of fisheries resources composition in the coastal ecosystem of the middle Yellow Sea of Korea","authors":"Jae Bong Lee, Jong Hee Lee, Y. Shin, C. Zhang, H. Cha","doi":"10.3796/KSFT.2010.46.2.126","DOIUrl":"https://doi.org/10.3796/KSFT.2010.46.2.126","url":null,"abstract":"To investigate seasonal variation of fisheries resources composition and their correlationships withenvironmental facotrs in the coastal ecosystem of the middle Yellow Sea of Korea, shrimp beam trawl werecarried out for the fisheries survey. Fisheries resources of 81 species, 57 families, and 6 taxa totally werecollected by shrimp beam trawl in the middle coastal ecosystem of Yellow Sea of Korea. Species were included6 species in Bivalvia, 6 in Cephalopoda, 22 in Crustacea, 2 in Echinodermata, 5 in Gastropoda, and 40 in Pisces.Diversity indices (Shannon index, H) showed seasonal variation with low value of 2.14 in winter, and highvalue of 2.67 in spring. Main dominant species were","PeriodicalId":211073,"journal":{"name":"Bulletin of The Korean Society of Fisheries Technology","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126102971","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}
Pub Date : 2010-05-31DOI: 10.3796/KSFT.2010.46.2.165
Kyounghoon Lee, Dae-jae Lee, Hyung-seok Kim, Seong-wook Park
) migratedoffshore Funka Bay of Hokkaido using an acoustic Doppler current profiler (OceanSurveyor, RDI,153.6kHz) established in T/S Ushio-maru of Hokkaido University, in September 27, 2003. The ADCPsdoppler shift revealed as the raw data that the maximum swimming velocity was measured 163.0cm/s, andits horizontal swimming speed and direction were 72.424.1 cm/s, 160.122.3 while the surroundingcurrent speed and direction were 19.68.4cm/s, 328.1 45.3 . To calculate the actual swimming speed ofPacific saury in each bins, comparisons for each stratified bins must be made between the mean surroundingcurrent velocity vectors, measured for each stratified bin, and its mean swimming velocity vectors, assumedby reference (threshold70dB) and 5dB margin among four beams of ADCP. As a result, the actualaveraged swimming velocity was 88.6cm/s and the averaged 3-D swimming velocity was 91.3cm/s using the3-D velocity vector, respectively. Keywords: Acoustic Doppler Current Profiler, Pacific saury, swimming speed, 3-D velocity vector
{"title":"Swimming speed measurement of Pacific saury (Cololabis saira) using Acoustic Doppler Current Profiler","authors":"Kyounghoon Lee, Dae-jae Lee, Hyung-seok Kim, Seong-wook Park","doi":"10.3796/KSFT.2010.46.2.165","DOIUrl":"https://doi.org/10.3796/KSFT.2010.46.2.165","url":null,"abstract":") migratedoffshore Funka Bay of Hokkaido using an acoustic Doppler current profiler (OceanSurveyor, RDI,153.6kHz) established in T/S Ushio-maru of Hokkaido University, in September 27, 2003. The ADCPsdoppler shift revealed as the raw data that the maximum swimming velocity was measured 163.0cm/s, andits horizontal swimming speed and direction were 72.424.1 cm/s, 160.122.3 while the surroundingcurrent speed and direction were 19.68.4cm/s, 328.1 45.3 . To calculate the actual swimming speed ofPacific saury in each bins, comparisons for each stratified bins must be made between the mean surroundingcurrent velocity vectors, measured for each stratified bin, and its mean swimming velocity vectors, assumedby reference (threshold70dB) and 5dB margin among four beams of ADCP. As a result, the actualaveraged swimming velocity was 88.6cm/s and the averaged 3-D swimming velocity was 91.3cm/s using the3-D velocity vector, respectively. Keywords: Acoustic Doppler Current Profiler, Pacific saury, swimming speed, 3-D velocity vector","PeriodicalId":211073,"journal":{"name":"Bulletin of The Korean Society of Fisheries Technology","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131847386","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}
Pub Date : 2010-05-31DOI: 10.3796/KSFT.2010.46.2.103
Bong-Seong Bae, Heui–Chun An, Hae-Hoon Park, Chang–Doo Park, Yongsu Yang
For an effective management of fisheries resources, we need fisheries informations necessary for theestablishment of reasonable fishing effort and TAC distribution. To study the present state of by-catch anddiscard of gill-net fishery in the East Sea, we carried out fishing research using trammel nets in the coastalsea of Susan-port (Yangyang), Jangho-port (Samcheok) and Hupo-port (Uljin). As a result, a total of catchof Susan was 259,172g and that of Hopo was 577,638g. Thus Catch of Susan was 1.49 times more than thatof Hupo considering the number of used fishing gear. And catch of Janho was 7.4 times more than that ofSusan considering the number of experiment. Two methods of by-catch analysis in this study were used, onemethod is standardizing of listed species catching possible in fishing license, another method is regardingcatch species under 1% of total catch as by-catch. As a result of by-catch analysis of two method, by-catchrate of Susan was 6.55% and 5.87% respectively, that of Hupo was 44.70% and 5.24% and that of Janghowas 0.96% and 2.31%. Discard rate of fish in Susan, Hupo and Jangho were 1.59%, 3.42%, 2.23%respectively.Keywords: Fishing capacity, Trammel nets, By-catch, Discard
{"title":"Catch characteristic and present condition of by-catch & discard of trammel nets fishery in the East Sea","authors":"Bong-Seong Bae, Heui–Chun An, Hae-Hoon Park, Chang–Doo Park, Yongsu Yang","doi":"10.3796/KSFT.2010.46.2.103","DOIUrl":"https://doi.org/10.3796/KSFT.2010.46.2.103","url":null,"abstract":"For an effective management of fisheries resources, we need fisheries informations necessary for theestablishment of reasonable fishing effort and TAC distribution. To study the present state of by-catch anddiscard of gill-net fishery in the East Sea, we carried out fishing research using trammel nets in the coastalsea of Susan-port (Yangyang), Jangho-port (Samcheok) and Hupo-port (Uljin). As a result, a total of catchof Susan was 259,172g and that of Hopo was 577,638g. Thus Catch of Susan was 1.49 times more than thatof Hupo considering the number of used fishing gear. And catch of Janho was 7.4 times more than that ofSusan considering the number of experiment. Two methods of by-catch analysis in this study were used, onemethod is standardizing of listed species catching possible in fishing license, another method is regardingcatch species under 1% of total catch as by-catch. As a result of by-catch analysis of two method, by-catchrate of Susan was 6.55% and 5.87% respectively, that of Hupo was 44.70% and 5.24% and that of Janghowas 0.96% and 2.31%. Discard rate of fish in Susan, Hupo and Jangho were 1.59%, 3.42%, 2.23%respectively.Keywords: Fishing capacity, Trammel nets, By-catch, Discard","PeriodicalId":211073,"journal":{"name":"Bulletin of The Korean Society of Fisheries Technology","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126025380","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}
Pub Date : 2010-05-31DOI: 10.3796/KSFT.2010.46.2.173
Dae-jae Lee, Wonseok Lee
In a split beam echo sounder, the transducer design needs to have minimal side lobes because the angular position and level of the side lobes establishes the usable signal level and phase angle limits for determining target strength. In order to suppress effectively the generation of unwanted side lobes in the directivity pattern of split beam transducer, the spacing and size of the transducer elements need to be controlled less than half of a wavelength. With this purpose, a 50 kHz tonpilz type transducer with a half-wavelength diameter in relation to the development of a split beam transducer was designed using the equivalent circuit model, and the underwater performance characteristics were measured and analyzed. From the in-air and in-water impedance responses, the measured value of the electro-acoustic conversion efficiency for the designed transducer was 51.6%. A maximum transmitting voltage response (TVR) value of 172.25dB re at 1m was achieved at 52.92kHz with a specially designed matching network and the quality factor was 10.3 with the transmitting bandwidth of 5.14kHz. A maximum receiving sensitivity (SRT) of -183.57dB re was measured at 51.45kHz and the receiving bandwidth at -3dB was 1.71kHz. These results suggest that the designed tonpilz type transducer can be effectively used in the development of a split beam transducer for a 50kHz fish sizing echo sounder.
{"title":"Design, fabrication and performance characteristics of a 50kHz tonpilz type transducer with a half-wavelength diameter","authors":"Dae-jae Lee, Wonseok Lee","doi":"10.3796/KSFT.2010.46.2.173","DOIUrl":"https://doi.org/10.3796/KSFT.2010.46.2.173","url":null,"abstract":"In a split beam echo sounder, the transducer design needs to have minimal side lobes because the angular position and level of the side lobes establishes the usable signal level and phase angle limits for determining target strength. In order to suppress effectively the generation of unwanted side lobes in the directivity pattern of split beam transducer, the spacing and size of the transducer elements need to be controlled less than half of a wavelength. With this purpose, a 50 kHz tonpilz type transducer with a half-wavelength diameter in relation to the development of a split beam transducer was designed using the equivalent circuit model, and the underwater performance characteristics were measured and analyzed. From the in-air and in-water impedance responses, the measured value of the electro-acoustic conversion efficiency for the designed transducer was 51.6%. A maximum transmitting voltage response (TVR) value of 172.25dB re at 1m was achieved at 52.92kHz with a specially designed matching network and the quality factor was 10.3 with the transmitting bandwidth of 5.14kHz. A maximum receiving sensitivity (SRT) of -183.57dB re was measured at 51.45kHz and the receiving bandwidth at -3dB was 1.71kHz. These results suggest that the designed tonpilz type transducer can be effectively used in the development of a split beam transducer for a 50kHz fish sizing echo sounder.","PeriodicalId":211073,"journal":{"name":"Bulletin of The Korean Society of Fisheries Technology","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117132585","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}
Pub Date : 2010-05-31DOI: 10.3796/KSFT.2010.46.2.115
S. Kim, Ju-Hee Lee, Hyung-seok Kim, Seong-wook Park
In order to design the optimal escape vent for the coon strip shrimp pot, the tank experiments were conducted with the model pot of five different slit height and slit width, respectively. The optimal height and width of escape vent were determined to 20mm and 40mm by tank experiments, respectively. These were determined by the 50% selection carapace length which was denoted to 25mm in selectivity curve. The escape experiments were conducted to determine a number of escape vent with the original shrimp pot to be set the designed escape vent from 2 vents to 10 vents increasing at intervals of 2 vents in tank. The optimal number of escape vents denoted 8 vents. Therefore, to apply the escape vent in commercial shrimp pot will be efficient to reduce small size shrimps to catch.
{"title":"Optimal design of escape vent for the dome type coonstrip shrimp (Pandalus hypsinotus) pot","authors":"S. Kim, Ju-Hee Lee, Hyung-seok Kim, Seong-wook Park","doi":"10.3796/KSFT.2010.46.2.115","DOIUrl":"https://doi.org/10.3796/KSFT.2010.46.2.115","url":null,"abstract":"In order to design the optimal escape vent for the coon strip shrimp pot, the tank experiments were conducted with the model pot of five different slit height and slit width, respectively. The optimal height and width of escape vent were determined to 20mm and 40mm by tank experiments, respectively. These were determined by the 50% selection carapace length which was denoted to 25mm in selectivity curve. The escape experiments were conducted to determine a number of escape vent with the original shrimp pot to be set the designed escape vent from 2 vents to 10 vents increasing at intervals of 2 vents in tank. The optimal number of escape vents denoted 8 vents. Therefore, to apply the escape vent in commercial shrimp pot will be efficient to reduce small size shrimps to catch.","PeriodicalId":211073,"journal":{"name":"Bulletin of The Korean Society of Fisheries Technology","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129891890","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}
Pub Date : 2010-05-31DOI: 10.3796/KSFT.2010.46.2.157
Seung-jong Lee, Yoo-Won， Lee, Joo-Il Kim, T. Oh, Bokyu Hwang, Byung-Yeob Kim, Kyounghoon Lee
The indirect target strength (TS) estimation method which uses the Kirchhoff ray mode model (KRM model) was discussed to apply for a biomass estimation in the water of mixed species. TS of 25 live scorpion fishes for 120kHz were measured by a tethered method and of others dominant 5 species in the marine ranching ground of Jeju coastal water including a scorpion fish were also estimated by KRM model. The measurement TS of scorpion fish well agreed with the theoretical values and the standard formula of scorpion fish was estimated as $TS_{120kHz}
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