• 수산해양기술연구
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• 제27권4호
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• pp.266-277
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• 1991

분사류의 해저 굴삭성능을 이용하여 해저의 모래속에 서식하고 있는 개량조개, Mactra chinensis(PHILIPPI)를 어획하기 위해, 전보의 분사노즐의 모래면 굴삭성능에 관한 수조실험 결과를 근거로 분사식 항망 시험어구를 제작하고, 군산 앞바다의 개량조개 어장에서 1990년 10월 5일에서 10월 30일까지 현장실험을 실시한 결과는 다음과 같다. 1) 시험어구의 굴삭깊이는 분사속도 1200cm/s일 때 10~11cm, 1350cm/s일 때 11~13cm, 1500cm/s일 때 13~14cm 이상이었다. 2) 예망장력은 예망속도 6.7cm/s에서 105$\pm$5kg으로 매우 작았다. 3) 단위소해면적당 평균어획량은 0.42kg/m 상(2)으로 재래식 형망에 비해 1.2~1.6배로 많았다. 4) 분사식 항망시험 어구는 조개를 파손시키지 않아 어획물에 파손패가 거의 없었다. 5) 분사류에 의한 어장의 탁도 변화량은 수심, 유속, 저질등에 따라 다소 다르나, 표층에서는 수심 5.2m이상이면 변화량을 볼 수 없고, 해저면상 3m의 저층에서는 어구의 후방 1m에서 9~11ppm으로 최대치를 보였으나, 점차 감소되어 9m 후방 이후에서는 변화량이 거의 없었다.

• 대한안전경영과학회지
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• 제11권2호
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• pp.95-101
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• 2009

The present study is to estimate the effect of wave height affecting at the front face of breakwater systems due to specification of submarine trench such as distance from breakwater to dredged area and width of dredge. The wave diffraction field, which is important hydraulic factor in the ocean, is considered to be two dimensional(2D) plane and the configuration of the submarine dredge on the sea bed designated by single horizontal long-rectangular pit system according to the various specific conditions of dredged locations. The numerical simulation is performed by using Green function based on the boundary integral equation and meshed at moving boundary conditions. The results of present numerical simulations are illustrated by applying the normal incidence. It is shown that the ratios of wave height at the front face of breakwater was varied by dependance of distant from breakwater to dredged area and width of dredge. It means that, when the navigation channel or pit breakwater is dredged on seabed, engineers have to consider the specification of dredge. This study can effectively be utilized for safety assessment to various breakwater systems in the ocean field and provided for safety construction of offshore structure.

• 수산해양기술연구
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• 제35권4호
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• pp.366-376
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• 1999

In order to examine the catching selectivity of the ark shell(Scapharca broughtonii) dredge, the various factors affecting the selective action of the dredge are analyzed, and the probabilities of the ark shell not shifting through the gaps between the teeth, and the mesh of the netting bag, are calculated for the various shell lengths, using the relation between the posture and the length when the shell passes through these parts.Considering that the probability of making catch is the product of the both probabilities described above, and that this probability is proportional to the relative catching efficiency, the selectivity curves for the ark shell dredge were estimated for various gaps between the teeth and for the various mesh sizes of the netting bag. The obtained results are summarized as follows :1. The ratios of the shell length of ark shell to the distance between teeth indicating the relative catching efficiency of 0%, 50, 100% respectively were 1.0, 1.26~1.28, 1.47~1.44, and that the selection ranges of selective shell length by the distance between teeth were 0.47~0.44, where the distances between teeth were 3.2cm, 3.6cm, 4.0cm, 4.4cm and 4.8cm. 2. The ratios of the shell length of ark shell to the mesh size indicating the relative catching efficiency of 0%, 50%, 100% respectively were 0.67, 0.84, 0.97 and that the selection range of shell length for catching, that in the range of selective shell length by the mesh size was 0.31, where the distance of 4.0cm between teeth, mesh size of 6.0 cm and the smaller mesh angle of $60^{\circ}$3. Where the distance between teeth is 4.0 cm and the smaller mesh angle is $60^{\circ}$, the selection range of shell length for catching of the ark shell dredge is decreased according to the mesh size, and it is minimized by 0.20 in the mesh size of 9.0~10.0 cm, but increased in the mesh size of over 11.0 cm. 4. Where the distance between teeth is 4.0 cm, the selective action by the mesh size of netting bag is begun with the mesh size of over 10.0 cm.

• 수산해양기술연구
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• 제36권4호
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• pp.267-273
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• 2000

민들조개 형망의 갈퀴에 의해 어획될 확률을 조개크기와 갈퀴간격 사이의 관계로부터 구했다. 이때 기존의 방법에서는 각장만을 이용했는데 여기서는 각장 이외에 각고(또는 각폭)에 의한 효과를 추가시켜 어획될 확률을 구하고 로지스틱 어획선택성 곡선에 적합시켰으며, 그식은 다음과 같았다. P=(equation omitted)$.$민들조개의 경우 생물학적 최소형은 각장이 25mm인 것으로 알려져 있으며, 이 최소성숙각장에 대해 50% 어획될 갈퀴간격을 구하면 16.2mm이다. 따라서, 민들조개 형망의 적정 갈퀴간격은 기존에 사용하고 있는 12mm를 16mm로 늘리는 것이 자원보호상 바람직하며, 이것은 예망작업시 모래 속을 끄는 갈퀴의 갯수도 상대적으로 적어지므로 어구저항이 감소되어 연료가 절약되며, 선상에서는 작은 조개를 체를 이용하여 거르는 인력작업도 줄일 것으로 여겨진다.

• 수산해양기술연구
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• 제53권3호
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• pp.266-275
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• 2017

The maximum sustained yield (MSY) of shellfish caught through dredge fishery was 7,250 to 7,490 MT from 1990 to 1999, which was not affected by the construction of the Saemangeum Dike. The MSY from 2000 to 2016, under the influence of the dike, was 1,716 to 1,776 MT when the total annual fish catch was 1,000 MT or more, and 289 to 336 MT when it was less than 1,000 MT. The construction of the Saemangeum Dike led to a decrease in the catch volume of the offshore dredge fishery in Jeollabuk-do, to 4.2 to 23.7% of that before its construction. The allowable biological catch (ABC) was estimated to be 313 to 1,532 MT per year, which was about 72.3 to 94.3% less than before the construction of Saemangeum Dike. Currently, the dredge fishery in Jeollabuk-do relies on comb pen shells. For fishery management, the catch per vessel should be set at 51.0 MT/year or less, and the number of fishing vessels should be reduced to 22 as quickly as possible. Besides, in the long term, the number of current fishing vessels should be reduced to less than half in consideration of the comb pen shell collecting period in Jeollabuk-do.

• 한국수산과학회지
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• 제28권6호
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• pp.720-727
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• 1995

A Monte Carlo computer simulation study was conducted to determine the most efficient sampling design for the blue crab dredge capture efficiency experiment performed in Chesapeake Bay, Maryland, U. S. A. The input values were the number of dredge tracks in each experimental area, the number of tows per experiment, the number of experiments, the mean density of crabs per unit area, the negative binomial coefficient, the gear capture efficiency, and the tow error. As a result of the study, a four-track experiment with twenty to twenty-eight tows was estimated to be the best in terms of precision and accuracy of the gear capture efficiency.

• 수산해양기술연구
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• 제59권4호
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• pp.290-300
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• 2023

This study aimed to identify the actual catch situation of offshore dredge gear which is newly regulated in the legislation. It's also conducted to identify the species composition, weight of the catch including the target species and incidental catches, and to provide the basic information necessary for the resource management of aquatic organisms caught by offshore dredge. During the investigation period (from September 2022 to May 2023), a total of 61 species appeared in the test operation sea of Boryeong, Chungcheongnam-do and Gunsan, Jeollabuk-do, with 31 species of fishes, 11 species of malacostraca, six species of gastropoda, five species of bivalvia, three species of cephalopoda, three species of asteroidea, one species each of asteroidea and holothuroidea appeared. According to the results of the test operation conducted in September and November 2022, the non-catch season of Atrina (Servatrina) pectinata, 1,203 shellfishes were caught out of 2,979 caught in number, showing a bycatch rate of 59.6%, and by weight, 157.9 kg of shellfish was caught out of the total catch of 448.4 kg, showing a bycatch rate of 64.8%. On the other hand, in February and May 2023, the catch season for Atrina (Servatrina) pectinata, 3,692 fishsells were caught out of the 4,232 catches in total, showing a bycatch rate of 12.8%, and by weight, 1,185.0 kg of shellfish was caught out of the total catch of 1,293.2 kg, showing an 8.3% bycatch rate.

• 한국농공학회논문집
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• 제48권2호
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• pp.45-55
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• 2006

This study analyze the hydrologic conditions and the effects of selected runoff characteristics as an attempt to estimate the optimal dredge amount for Asan Lake in Korea. The runoff feature was calculated by utilizing the water balance simulation from DIROM (Daily Irrigation Reservoir Operation Model), which allowed changes in landuse to be quantified using remote sensing for 14 years. The distribution of prospective sediment deposits was been tallied based on the changes in landuse, and quantity of incoming sediment estimated. From these findings, we were then able to simulate the fluctuation of water level, gauging the pumping days not already in use, to determine the frequency of the distribution for around the. requirement annual water storage and the changing water level. The optimal dredge amount was calculated on the basis of the distribution of frequency, taking into account the design criteria for agricultural water with the 10-year frequency of resistant capacity.

• 수산해양기술연구
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• 제33권1호
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• pp.1-8
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• 1997

To find the tooth selectivity of the dredge for catching the ark shell Scapharca broughtonii, the probabilities of the ark shells which are not sifting through the gaps between teeth were calculated for the various shell lengths. Considering that these probabilities are in proportion to the relative catching efficiencies, selectivity curves for the ark shell dredge were estimated for the various gaps between teeth. The ratio of the shell length of ark shell to the distance between teeth indicating the relative catching efficiencies of 0%, 50%, 100% respectively, were calculated by using these selectivity curves, and the values were 1.00, 1.32, 1.54 in the distance of 4.0cm between teeth and then, the ratios showed a slight tendency to decrease as the distance between teeth increased in the relative catching efficiency of 100%, In addition, the range of shell length for catching, that is, the range of selective shell length by the distance between teeth was 0.54 in the distance of 4.0cm between teeth.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 추계학술발표회
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• pp.216-219
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• 2001

In this study, a hydrocyclone operated by centrifugal force was examined as a part of dredge system of lake sediments. It does not help dehydration of the sediments, but also enables the classification of fine particles in the stable and sanitary treatment. Several experiments were performed focusing on the separation efficiency under the condition of room temperature with virtual sediment samples and simulated particles. As a result of the experiment, it was found that the apex size of the cyclone greatly affected the cut diameter(d$_{50}$), and high density particles were separated more effectively.y.