Yongsu Yang

Development of a low-energy used large midwater trawl using a numerical method

Fuel consumption in fisheries is a primary concern due to environmental effects and costs to fishermen. Much research has been carried out to reduce the fuel consumption related to fishing operations. The fuel consumption of fishing gear during fishing operation is generally related to hydrodynamic resistance on the gear. This research demonstrates a new approach using numerical methods to reduce fuel consumption. The results from the simulation were verified with results that mirrored the model experiments. By designing the fishing gear using drawing software, the whole and partial resistance force on the gear can be calculated as a result of simulations. The simulation results will suggest suitable materials or gear structure for reducing the hydrodynamic forces on the gear while maintaining the performance of the gear. Furthermore, the efficiency of low energy used trawl as economic point of view will be dealt. This research will helpful to reduce the GHG emissions from fishing operations and lead to reduce fishing costs due to fuel savings.

The estimation of the optimum mesh size selectivity of a drift net for yellow croaker (Larimichthys polyactis) using by the SELECT model

참조기는 우리나라에서 오래 전부터 고급으로취급하고 있는 대표적인 어종 중의 하나로 우리나라 남서해 연안과 동중국해 등의 해역에서주로 어획되고 있다 . 최근 참조기 자원량은 증감을반복하고 있으나 전반적으로 감소 추세에 있다. 이와 더불어 주요 어장인 동중국해에서는 어획노력량이 과다하게 투입되고 있고 중국 어선들과 경쟁조업 등으로 유자망어업의 경우 어장사고가 빈번히 발생하고 있다 . 특히 생태적인 측면에서는 자원 감소로 인하여 개체의 성장과 성숙이 매우 빨라짐에 따라 성숙개체의 체장이 소형화되고 있다 . 이러한 관점에서 우리나라에서는남서해안 참조기를 자원 회복 대상어종으로

Weight estimation of the sea cucumber (Stichopus japonicas) using vision-based volume measurement

Growth analysis and selection of sea cucumbers (Stichopus japonicas) is typically performed through length or weight measurements. However, because sea cucumbers continuously change shape depending on the external environment, weight measurement has been the preferred approach. Weight measurements require extensive time and labor, moreover it is often difficult to accurately weigh sea cucumbers because of their wet surface. The present study measured sea cucumber features, including the body length, width, and thickness, by using a vision system and regression analysis to generate R 2 values that were used to develop a weight estimation algorithm. The R 2 value between the actual volume and weight of the sea cucumbers was 0.999, which was relatively high. Evaluation of the performance of this algorithm using cross-validation showed that the root mean square error and worst-case prediction error were 1.434 g and ±5.879 g, respectively. In addition, the present study confirmed that the proposed weight estimation algorithm and single slide rail device for weight measurement can measure weights at approximately 4,500 sea cucumbers per hour.

Vision-based Automatic System for Non-contact Measurement of Morphometric Characteristics of Flatfish

This paper introduces a vision-based automatic system (VAMS) for non-contact measurement of morphometric characteristics of flatfish, such as total length (TL), body width (BW), height (H), and weight (W). The H and W are simply measured by a laser displacement and a load cell, respectively. The TL and BW are measured by a proposed morphological image processing algorithm. The proposed algorithm cans measurement, when the tail of flatfish is deformed, and when it is randomly oriented. In the experiment, the average and maximum measurement errors were recorded, and standard deviations and coefficients of variation (CVs) for the measurements were calculated. From those results, when flatfish the TL measurements had an average of 266.844 mm, a standard deviation of 0.351 mm, a CV of 0.131%, and a maximum error of 0.87 mm with straightened flatfish (TL A : 267 mm, BW A : 141 mm), and when flatfish of different sizes were measured, the errors in the TL and BW measurements were both about 0.2 %. Using a single conveyor, the VAMS can process up to 900 fishes per hour. Moreover, it can measure morphometric characteristics of flatfish with a TL of up to 500 mm.

Development and efficiency of filter device for the emission reduction from the diesel engine in fishing boat

온실가스의 발생량은 산업의 발달과 함께 증가하였으며 , 산업에서의 생산량과 비례하여 증가한다 . 수산업이전체 산업 중상대적으로 적은 부분을 차지하고 있으나, 우리나라 수산업 생산량 규모는 2006 년세계 13 위,수출금액 세계 26 위에 있으며 , 과거 1989 년생산량 세계8위, 수출 세계 6위에 이른 적도 있다 . 2010 년농림어업생산액은 50 조9490 억원이며 , 이중 어업생산액은 7.4 조원을 차지하고 있다 . 어업에 종사하고 있는 어선의 수는2009 년기준 78,262 척이 등록되어 있다 . 연근해어업 어선은 총어선수의 70% 를차지하고 , 전체 어선의 크기에서는 43% 로가장 높은 비율을 차지하고 있다 . 한편 , 어선으로 분류되지 않는 선박은 2009 년12 월자료에 따르면전체 8,374 척이 등록되어 있으며 총톤수는13,916,563 GT 이다 . 어선은 일반 선박과 비교하여 총톤수에서 전체 선박 중4% 의비율을 차지하고 있으나 배의척수에서는 전체의 90% 를차지하고 있다 (NFRDI ,2012)우리나라 어선 총수에서 가장 많은 부분을 차지하는어선의 선령이 6－15 년사이에 밀집되어 있으며 , 이러한어선의 엔진 또한 노후화되어 있다 . 선단 규모로 조업을 하는 대형선망 , 기선저인망 등은 어획성능을 유지

Estimation of Green-House-Gas emissions from domestic eel farm

The purpose of the study is to estimate the Green-House-Gas (GHG) emissions from domestic eel farm in the water recirculation system or still-water system by the assessment of energy consumptions and GHG emissions for establishing to reduce standards of GHG from a sustainable perspective. GHG emission components as seeds, feed, fuel, electricity, fixed capital, fish respiration, and others were analysed at the different culture type between water recirculation system and still-water system by 3 stage farm size of small, medium, large scale. The result showed that the mean GHG emission of the eel farm was in the stage of production per fish 1kg at different culture type and farm size. Therefore it could be useful for policy, planning, and regulation of aquaculture development with establishing GHG reduction standards.

Acoustic monitoring using multi-beam imaging sonar through a set net in the Southern Sea, Korea

This study investigated a method for monitoring fish flux though a set net in the coastal South Sea, Korea, using sideward-looking wide angle multi-beam imaging sonar (blueview). This data set was used to examine the impact of changes in diel variation and current speed from a set net. During nighttime, the influx of fish in the set net was significantly 22 times higher than in daytime. The time when high fish flux was observed corresponded to the time of low current speed during nighttime. In contrast, the fish flux was not affecting current speed during daytime. The study provides implications for understanding fish behavior through use of a set net.

Design of an Optimum Computer Vision-Based Automatic Abalone (Haliotis discus hannai) Grading Algorithm

An automatic abalone grading algorithm that estimates abalone weights on the basis of computer vision using 2D images is developed and tested. The algorithm overcomes the problems experienced by conventional abalone grading methods that utilize manual sorting and mechanical automatic grading. To design an optimal algorithm, a regression formula and R(2) value were investigated by performing a regression analysis for each of total length, body width, thickness, view area, and actual volume against abalone weights. The R(2) value between the actual volume and abalone weight was 0.999, showing a relatively high correlation. As a result, to easily estimate the actual volumes of abalones based on computer vision, the volumes were calculated under the assumption that abalone shapes are half-oblate ellipsoids, and a regression formula was derived to estimate the volumes of abalones through linear regression analysis between the calculated and actual volumes. The final automatic abalone grading algorithm is designed using the abalone volume estimation regression formula derived from test results, and the actual volumes and abalone weights regression formula. In the range of abalones weighting from 16.51 to 128.01 g, the results of evaluation of the performance of algorithm via cross-validation indicate root mean square and worst-case prediction errors of are 2.8 and ±8 g, respectively.

A Study on Behaviour of Giant Pacific Octopus, Parotopus dofleini to Single Line Hook for Hook Design

The single line hook fishery for giant pacific octopus, Parotopus dofleini is one of the important in coastal Kangwon-do of Korea, where was caught an average of 4,000 ton during the period of 1996~2000. The fishing gear is consisted of a single buoy line, a buoy and a hook. In this study, the responses of giant pacific octopus to single line hook gear were examined in an experimental tank using a video camera in order to know hooking mechanism and improve hook. Giant pacific octopus tend to envelop the bait with their arms by rush or slowly swimming towards it. When they rush to the bait, they show much feeding behaviour as withdrawing after enveloping the bait using two arms. But when they approach with slowly swimming to bait, they show feeding behaviour as stopping after enveloping the bait using one arm. and then, the highly hooking rate appeared more often in the case of latter then former. The average feeding time on a sardine, giant pacific octopus and pork fat showed the range of 1 to 30 min, 10 to 50 min, and 50 min to over 1 hour, respectively. This indicates that it takes longer time for giant pacific octopus to eat the tough meat than the soft meat. The performance concerned with hooking showed that the `B` type hook with a short shank was more favorable than the `A` type hook with a long shank. However, the `A` type hook has the advantage of easy dropping out caught octopus, compared to the `B` type.

Acoustic monitoring using bamboo set net in the Southern Sea of Korea

High-temporal resolution profiles of acoustic backscatter were collected from a traditional bamboo set net along the coast of the Southern Sea, Korea, using sideward-looking multi-beam imaging sonar. These data were used to examine the impact of variations in tidal cycles and current speeds on the bamboo set net. The relatively high influx of fish during the nighttime compared to the low influx and high outflux of fish during the daytime suggests visual avoidance of the net by the fish during the daytime. The observed diel variation in the captured fish flux was significantly correlated with the current speed (day: r = 0.35, p = 0.002, night: r = 0.60, p < 0.001). The ratio of influx and outflux of fish, and current speed were correlated in a linear relationship (day: r = 0.45, p < 0.001; night: r = 0.56, p < 0.001). The fish activity of those inhabiting the bamboo set nets appears to be greatly influenced by day-night differences and current speed. The present study enhances understanding of fish behavior via utilization of a bamboo set net in the coastal zone.