• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.4
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• pp.267-274
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• 2001

A prototype experiment on the anchovy boat seine was carried out in the southern sea of korea to analyze the vertical opening and the underwater geometry. The vertical opening and the underwater geometry of the prototype net were determined by distance of Minilog position with the combinations of the distance between paired boats and the towing speed. The results osbtained can be summarized as follows; 1. Vertical opening of the protype net was gradually lowered according to the increase of the distance between paired beats and the towing speed. 2. Vertical opening of Wing net, Inside wing net, Square, Fore bag net, Flapper and After bag net of the prototype net according to the distance between paired boats were varied in the range of 8.4~9.0, 15.7~17.4, 12.9~17.9, 13.6~19.0, 8.3~8.4, 11.1~14.7m respectively, varied in the range of 12~16, 22~24, 27~38, 59~83, 92~93, 41~54% of the normal opening respectively. 3. Vertical opening of Wing net, In side wing net, Square, Fore bag net, Flapper and After bag net of the prototype net according to the towing speed were varied in the range of 7.7~10.5, 19.6~21.6, 12.2~16.9, 15.4~17.1, 8.0~8.2, 13.7~14.7m respectively, varied in the range of 14~19, 27~30, 32~36, 67~74, 89~91, 51~54% of the normal opening respectively. 4. Prototype net was appeared apparent the pocket shape, because Wing net and Inside wing net was opened 20% of the normal opening. 5. Working depth of the prototype net was gradually shallow according to the increase of the distance between paired boats and the towing speed.

• The Journal of Fisheries Business Administration
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• v.24 no.2
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• pp.69-82
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• 1993

The purpose of this paper is to estimate production function in the coastal fishing, especially long bag set net fishing and trap fishing using Cobb-Douglas production function with the three main variables: fishing quantity per tonage(WQFP), the number of working persons per tonage(WEMP), and the number of utilized fishing equipments per tonage(WEQU). The statistical results of such estimation reveal that fishing quantity per tonage can be expressed as a function of the number of working persons per tonage and the number of utilized fishing equipments per tonage. The estimated coefficients of WEMP and WEQU are statistically significant and also satisfy the requirements of Cobb-Douglas production function. This study also estimates marginal rate of technical substitution of labor in terms of capital (MRT $S_{LK}$ )in each long bag set net fishing and trap fishing. The resuits of this study show us that trap fishing has the technical characteristic of constant returns to scale(CRS) but long bag net fishing has that of decreassing returns to scale(DRS).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.4
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• pp.287-298
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• 2000

The charge of distance and the change of tack between paired boats were measured by ship's distance measuring system fixed MCS in the main boat and MS in the following boat. The operating depth of the anchovy boat seine was recorded and analysed by self memory temperature/depth sensor in order to compare the relationship between the distance between towing boats and geometry of the anchovy boat seine net. The results are as follow, (1) When distance between paired boat was 5m, the fishing net was spreaded down deeply and unstably in accordance with bag net and flapper may be help to pass out anchovy school. (2) When distance between paired boat was 100m, vertical opening of the net was gradually increased with higher slope of towing depth in the square, bosom and flapper. Therefore, fishing efficiency could be decreased by preventing the entering of anchovy due to unstable shape of the bag net. (3) When distance between paired boat was 200m, the geometry of the anchovy seine was stable condition with the end of bag net was up while flapper was down and it may cause bad effect in fishing efficiency. (4) When distance between paired boat was 300m, the shape from wing net to bag net was gradually slow down and stable enough as well as good shape in bag net and flapper. (5) The ship's distance measuring system could be used for measurement and accurate control of distance between paired boat in accordance of anchovy recordings by fish finder in order to get higher fishing efficiency in anchory boat seine operation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.4
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• pp.299-308
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• 2000

A model experiment on the anchovy boat seine was carried out in the southern sea of korea to analyze the vertical opening and the underwater geometry. The model net A was made of half size in the length and width of the prototype net. The model net B was attached floats and chain to the model net-A. The vertical opening and the underwater geometry of the model net were determined by distance of Minilog position with the combinations of the distance between paired boats and the towing speed. The results obtained can be summarized as follows; 1. Vertical opening of the model net was gradually lowered according to the increase of the distance between paired beats and the towing speed. 2. Vertical opening of Wing net, In side wing net, Square, Fore bag net, Flapper and After bag net of the model net A according to the distance between paired boats were varied in the range of 10.8~9.0, 12.0~8.3, 12.6~9.0, 10.4~6.6, 4.6~5.2, 8.8~7.7m respectively, varied in the range of 36~30, 21~15, 31~22, 80~51, 80~96, 59~51% of the normal opening respectively 3. Vertical opening of Wing net, In side wing net, Square, Fore bag net, Flapper and After bag net of the model net B according to the distance between paired boats were varied in the range of 9.1~8.5, 9.8~6.5, 11.2~8.0, 11.0~8.1, 4.7~5.0, 7.0~7.5m respectively, varied in the range of 30~28, 18~12, 27~20, 85~62, 87~93, 47~50% of the normal opening respectively 4. Vertical opening of each a part of the model net according to the towing speed was as same as the former. 5. Model net was appeared apparent the pocket shape, because Wing net and Inside wing net was opened 30% of the normal opening. 6. The bosom and the bag net of the model net A were risen up to the upper lazer, this phenomenon was more apparent as the distance between paired boats and the towing speed increase, but the model net B was almost constant. 7. Working depth of the model net was gradually hallowed according to the increase of the distance between paired boats and the towing speed

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.1
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• pp.9-16
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• 2005

This study was conducted in order to improvement of fishing gear and fishing operating system for anchovy boat seine by labor saving improved nets. Field experiments were carried out observe geometry of nets and fishing operating system by catcher boats. The obtained results are summarized as follows : The Vertical net opening of fore wing net, wing net, inside wing net, square, fore bag net, flapper, after bag net of the labor saving improved net according to the distance between catcher boats were varied in the range of 5.0${\sim}$7.8, 14.4${\sim}$21.1, 16.2${\sim}$21.2, 14.0${\sim}$17.3, 11.7${\sim}$13.9, 5.4${\sim}$6.9, 8.2${\sim}$9.8m respectively, varied in the range of 50${\sim}$78, 25${\sim}$36, 24${\sim}$31, 31${\sim}$38, 61${\sim}$73, 71${\sim}$91, 87${\sim}$104% of the actual ratio of net opening in each part. Labor saving improved net was performed instant net opening in fore wing net and maintained stable net opening and towing depth by means of attached net pendant. Also, it was minimized as net pocket phenomenon leading to guide anchovy for more catch by means of attached body net. The opening in accordance with distance between catcher boats and towing speed. The catch of labor saving improved net was increased than traditional net due to decrement of net resistance by improvement of bag net leading to increasement of towing speed and reduction of escape anchovy as well as improve nets of whole operation system.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.4
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• pp.272-281
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• 2008

Seasonal and annual variation in the species composition of bag-net catch in the coastal waters of Incheon, Korea were examined from April 2000 to November 2004. To analyze seasonal variation of the fisheries data, we implemented a self-organizing map(SOM), an unsupervised artificial neural network, with the catch amount of 97 species. Over 5 years, we caught 68 species of fish, 23 species of crustaceans and six species of cephalopods. The total number of fish species were gradually increased during the study period. The number of species was higher during the spring than the autumn. The SOM identified four groups of the sampling months based on seasonal changes in communities. In the spring, the dominant species were Leptochela gracilis and Pholis fangi; whereas, in the autumn, Engraulis japonicus and Portunus trituberculatus were dominant species in bag-net catch. Our results will be used to estimate seasonal and annual variation in fisheries resources of Korean coastal waters.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.2
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• pp.101-106
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• 2005

This study was carried out to observe the underwater geometry of the anchovy boat seine by two fishing operation systems. One was a traditional operation system that used a fish detecting boat, another was a new operation system that used the same fishing gear with floats and sinkers in comparison with a fish detecting boat. Vertical opening of the fishing gear that used a casting net, working depth of each part of the fishing gear that used a new operation system was almost canstant, but was gradually shallow in a traditional operation system. Just before hauling net, working depth of each part of the fishing gear that used a new operation system was maintained stable, but was vertically unstable in a traditional operation system because as rear part of the fishing gear was risen up the upper layer. Just after hauling net, working depth of the fishing gear that used a new operation system was also maintained stable, and then anchovy school could be lead to bag net.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.4
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• pp.281-289
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• 2011

The purpose of this study is to identify the flow resistance of the bottom trawl net. The bottom trawl net being used in the training ship of Chonnam National University was selected as a full-scale net, and model nets such as 1/10, 1/25 and 1/50 of the actual net were made. Total resistance of the net part, the height of the net mouth and the flow resistance of components of the net such as wing, bag and cod-end part was measured, converted into full-scale and compared. Additionally, the model rule of Tauti (1934), which has been most frequently used in fishing net modeling experiments, was applied to interpret flow resistance and scale effect of model experiment was investigated. Presumed that the flow resistance R is $R=kS{\upsilon}^2$ against the flow velocity of each net ${\upsilon}$, resistance coefficient k was calculated by substituting R, ${\upsilon}$ and S of the net. From the result, it was found that k decreases exponentially when u increases which makes $k=c{\upsilon}^{-m}$. Whereas m of each net is ranged between 0.13-0.16 and there was not significant difference between nets. c does not show big difference in 1/10 and 1/25 model and the value itself was relatively bigger than in 1/50 model. The height of the net mouth of 1/25 and 1/50 model net h decreases exponentially according as ${\upsilon}$ increases to make $h=d{\upsilon}^{-n}$. Whereas d and n values were almost same in two nets. Additionally, when resistance of cod-end, wing and bag part in 1/25 and 1/50 model nets, both nets showed big resistance in bag part when flow is 1m/s as more than 60%. Wing and cod-end part showed almost same value or wing part had little bit larger value. On the other hand, when reviewing the reasons why both models showed difference in 1/50 model while c value against the resistance coefficient k did not show big difference in 1/10 and 1/25 model, it is inferred that the difference occurred not from material difference but from the difference in net size according to scale. It was judged that they are the scale effects concomitant to the model experiments.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.3
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• pp.28-36
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• 1982

Petri nets have been used for medeling a wide variety of systems from computer to social systems. This paper disusses Petri nets in the context of mathematical representation and its associated bag theory. The method of modeling systems such as event-condition, computer progranm computer operation and PERT chart is discribed and their Petri net representation are presented. Finally Petri net representation of tunnel diode oscillator circuit and the analysis of the circuit using Petri net are discussed with the program and results.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.2
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• pp.203-211
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• 2015

The purpose of this study is to identify the flow resistance of the bottom pair trawl nets. The bottom pair trawl nets being used in fishing vessel (100G/T, 550ps) was selected as a full-scale net, and 1/10, 1/25 and 1/50 of the model nets were made. Converted into the full-scale net by Tauti's modeling rule and Kim's modeling rule, when resistance coefficient k of each net was calculated by substituting into above equation for flow resistance R and wall area of nets S values of each net ${\upsilon}$. Because resistant coefficient k decreases exponentially according as flow velocity ${\upsilon}$ increases to make $k=c{\upsilon}^{-m}$, c and m values of each net were compared. As a result, as the model was smaller, c and m values was smaller in the two rule into standard of 1/10 model value, decrease degree of 1/25 model was almost same in the two rule, decrease degree of 1/50 model was very big in Tauti's modeling rule. Therefore, in the result of experiment, because average of c and m values for similarly 1/10 and 1/25 model were given $c=4.9(kgf{\cdot}s^2/m^4)$ and m=0.45, R (kgf) of bottom pair trawl net could show $R=4.9S{\upsilon}^{1.55}$ using these values. As in the order of cod-end, wing and bag part for 1/25 and 1/50 model net were removed in turn, measured flow resistance of each, converted into the full-scale, total resistance of the net and the resistance of each part net were calculated. The resistance ratio of each part for total net was not same in 1/25 and 1/50 model each other, but average of two nets was perfectly same area ratio of each part as the wing, bag and cod-end part was 43%, 45% and 12%. However, the resistance of each part divided area of the part, calculated the resistance of per unit area, wing and bag part were not big difference each other, while the resistance of cod-end part was very large.