• 수산경영론집
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• 제29권1호
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• pp.121-137
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• 1998

This study was conducted to examine the economic evaluation of the newly developed fish meal analog (BAIFA-M) in Korean rockfish feed. A raw fish feed (MP) and two commercially formulated diets (EP) were employed to compare weight gain (WG), feed conversion ratio (FCR) and survival rate (SR) from the sea cage culture system. By using the economic model in the practical sea cage culture system, feed cost, production cost and gross profit per kg production, rate of profit to gross revenue (RPGR), and internal rate of return (IRR) were calculated based upon the results of the experiment and the information of the private aquaculture farm (Young Chang) in Tong young, Korean. IRR criteria is one of the popular economic feasibility analysis methods applicable far aquaculture industry. This is an economic evaluation method to compare the given interest rate or the discount rate with IRR which can be calculated by the difference between the present value of the benefit stream and of the cost stream. The benefits of using EP on WG, FCR, SR, and production cost will be emphasized in this study. Fish averaging 20$\pm$3.6g (Mean$\pm$SD) were randomly distributed in each small cage (6m$\times$6m) as groups of 2,000 fish. By using 3 large size cages (12m$\times$12m), 12 small cages were constructed, and only 9 small cages were employed for three replicates of each diet treatment. To compare with MP diet, two sinking EP diets were designed by our laboratory and produced by the local feed company who wanted to promote these EP diets for the mass cage culture of Korean rockfish in the future. Two EP diets contain white fish meal and/or BAIFA-M as the main animal protein sources : WFM diet, maximum 43% of white fish meal : BAIEA- M diet, 30% of white fish meal nab replaced by BAIFA- M from WFM diet. Results are summarized in Table 1. Fish fed MP diet showed significantly lower SR than does fish fed two EP diets(P<0.05). However, there Were no significant difference on FCR among fish fed three practical diets. Table 1. Average feed conversion ratio (FCR), accumulative average survival rate (SR) and economic evaluation data far three practical diets. As we expected, BAIFA-M diet is more economical than WFM diet as well as MP diet. Feed cost and production cost per kg production from BAIEA - M diet were lower than those from WFM and MP diets. Moreover, gross profit per Kg production, RPGR and IRR from BAIFA- M diet were higher than those from WFM and MP diets. This economic evaluation study clearly indicated that MP diet should be replaced by the commerical formulated EP diets as soon as possible in the near future because MP diet is not economical in the practical sea cage culture system.

• 한국수산과학회지
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• 제34권1호
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• pp.43-50
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• 2001

규칙파, 불규칙파 및 파랑과 흐름이 공존하는 상태에서 프레임에 우리형 그물을 부착하여 구성되어 있는 가두리 시설의 운동특성을 분석하기 위하여 정사각형 및 원형 구조의 가두리 시설을 대상으로 예인 수조에서 수리 모형실험을 실시하였으며, 규칙파중 운동 특성은 선형 포텐셜 이론에 의한 수치 해석의 그것과 비교하였다. 그 결과는 다음과 같이 요약할 수 있다. 1) 규칙파중 모형 가두리 시설의 상하 및 종 동요는 전후 동요와는 달리 그물의 영향을 거의 받지 않았으므로 이 시설물의운동 특성중 가장 중요한 상하 동요를 해석하는 경우에는 그물을 제외하고 프레임만을 고려해도 된다는 것을 확인하였다. 2) 불규칙파중 및 파랑과 흐름이 공존하는 상태에서 모형 가두리 시설의 운동 특성은 입사파 주기의 2배 되는 고주파수에서 시설물의 고유 주기 등에 의해 동적 운동의 peak frequency가 나타남으로써 비선형 즉, 2nd order harmonic 성분이 존재하였다 3) 파동 및 흐름장에서 동요 특성이 정사각형에 비해 비교적 작게 나타난 원형이 파도, 조류 등 환경 조건이 거친 해역에 보다 적합한 것으로 판단되었다.

• 한국발생생물학회지:발생과생식
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• 제24권3호
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• pp.225-230
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• 2020

This study reports the presence of mature and bi-sexual phase gonads in red spotted grouper, Epinephelus akaara after less than a year of cultivation in a commercial indoor tank and a net cage. In December 2018, juveniles were placed in an indoor tank and cultured for five months. In June 2019, the fish were transferred to a net cage and cultured until September. The rearing temperatures ranged from 19.86℃-24.65℃ in the indoor tank and 21.86℃-27.65℃ in the net cage. During the net cage culture period, specimens were randomly selected for histological gonad examination. The highest gonadosomatic index (GSI) value was measured in July (3.38±2.53), and dramatically decreased in August (0.44±0.21) and September (0.42±0.30). In July, some mature fish showed signs of vitellogenic stage oocyte development (vitellogenic and oil droplet stage oocytes), but immature fish were in an early developmental stage containing peri-nucleolus stage (PNS) oocytes. Bi-sexual phase gonads containing spermatocytes and spermatids were observed in the lumen and several PNS oocytes. By August and September, most specimens showed early-stage ovary development. However, mature testis (in August) and bi-sexual phase gonads (in September) were also observed. These results provide evidence for early puberty and hermaphroditism in the red spotted grouper.

• 한국수산과학회지
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• 제55권5호
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• pp.598-611
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• 2022

The aim of this study was to investigate the range of influence of aquaculture activities in fish cage farms located on the southern coast of Korea (Farm A and B in Hadong, Farm C in Tongyoung, and Farm D in Geoje) by analyzing the distribution and characteristics of polychaete communities. Farm A and B showed remarkably high aquaculture intensity, and as a result, the polychaete communities near the farms were heavily polluted. However, there was a difference in the polychaete communities at a distance greater than 30 m from farm A and B, which may be due to topographical differences. The effect of the aquaculture activity of Farm C was only observed below the farm, however, the influence of aquaculture activities Farm D was maintained over a relatively long distance. According to the results of this study, the effect of the fish cage culture was mainly influenced by factors related to the production of fish, such as the stocking amount and the amount of food supply. Moreover, the distance at which the influence of aquaculture activity was observed was found to be closely related to the topographical characteristics and flow velocity around the farms.

• 한국양식학회지
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• 제16권2호
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• pp.84-87
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• 2003

Effect of artificial illumination on feeding by the rockfish Sebastes schlegeli receiving no synthetic feed in the cage of the Tongyong Marine Ranch was investigated by analysing the stomach contents of 20 individuals every month from October 1998 to July 1999. The fish was found to have fed on naturally available zooplanktons, i.e. Calanus sinicu, zoeae, amphipods and copepodites in October, fish larvae in November-December, nematodes in January, amphipods in February and again fish larvae from May to July. Despite increase in the weight of stomach contents from 260 mg/fish during the initial period of study to 2,173 mg/fish, as many as 70% of the fish were found to have empty stomach during March-April. Weight of stomach contents did not increase with increasing age of the fish. Occurrence frequency was 83-90% for C. sinicus during October-November and >50% for fish larvae during March-April and June-July.

• 한국해양학회지:바다
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• 제12권3호
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• pp.159-169
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• 2007

가두리 양식으로 인해 과잉 공급된 유기물은 연안의 저서생태계를 교란시키는 주요인의 하나로 알려져 왔다. 이 연구는 2003년 6월과 8월 가두리 밀집해역인 통영연안의 두 양식장(A, B)에서 가두리 양식으로 인한 유기물 오염이 저서동물군집, 특히 저서다모류군집에 미치는 영향 정도와 범위를 알아보기 위해 수행되었다. 다모류가 저서동물 군집의 개체수 조성에서 차지하는 비율은 각 조사선에서 $81%{\sim}87%$로 매우 높았다. 가두리로부터 거리가 증가함에 따라 다모류군집의 종 수, 밀도, 다양도 그리고 우점종의 분포 양상은 현격히 변하였다. 가두리로부터 10 m 이내에서는 유기물 오염지표종인 Capitella capitata가 우점하였으며, 종 수도 가장 낮아 군집이 유기물에 의해 심하게 교란 받고 있는 것으로 나타났다. 특히, C. capitata는 가두리 양식장의 밀집도가 상대적으로 높고 지형학적으로 보다 은폐된 양식장 A에서 최대 $18,410\;ind.m^{-2}$의 고밀도 출현 양상을 보였으며, 두 양식장의 거리에 따른 개체밀도와 다양도 패턴의 전체적인 차이를 좌우하였다. C. capitata의 개체수가 급감한 10 m 지점 이후 15 m까지 구간에서는 종 수가 급격히 증가하였다. 이런 종 수 및 밀도의 급격한 변화는 이 구간이 심한 유기물 오염 상태(highly polluted)에서 약한 유기물 오염 상태(slightly polluted)로 전환되는 추이점(ecotone point)임을 말해준다. $15{\sim}60m$ 구간에서는 종 수와 밀도의 추가적인 증가와 유지가 관찰되는 약한 유기물 오염 상태의 점이역(transitional zone)이 형성되었으며 군집의 주 구성원은 Lumbrineris longifolia, Aphelochaeta monilaris 등과 같은 잠재적 유기물 오염지시종들 이었다. K-우점도 곡선과 다차원 척도법의 결과도 앞의 군집변화와 일치하였다. 이 연구에서 저서다모류군집에 대한 유기물 오염의 영향은 가두리로부터 떨어진 거리, 가두리가 위치한 해역의 지형학적 특성 및 가두리 양식장의 밀집도에 의해 좌우되었다.

• 대한조선학회논문집
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• 제43권1호
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• pp.119-127
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• 2006

Recently as a result of excessive development. pollution of the coast and occurrence of a typhoon year after year, fishermen suffer heavy losses in fish farming which is the one of the most important earnings ways. For solution of these problems, we need to go out into the open sea from an inland sea. In this study we suggested new fish cage which makes up for the structural weakness of existing wooden fish cages. It can farm fishes in the open sea of high wave and current with no damages from a typhoon. We substituted TPU(Thermoplastic Polyurethane) air chamber for existing styrofoam flotage which was harmful to the environment and impermanent. We used PE(Polyethylene) pipes for the maintenance of formation and the prevention of buoyancy loss caused by a breakdown of flotage. PE b rackets were designed to combine PE pipes with TPU air-chamber flotage. It has good strength and light weight. As a result of modeling test. it is great in buoyancy, strength and flexibility against wave. Because it can control buoyancy arbitrarily, moreover, we expect that it will reduce damages of a red water by applying it as semi-submerged fish cages.

• 한국수산과학회지
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• 제31권2호
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• pp.217-225
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• 1998

가두리양식이 저서생태계에 미치는 영향을 파악하기 위하여 장두도의 해양목장화 가두리 예정해역과 저도의 기존 가두리 양식해역에 서식하는 중형저서생물군집을 조사하였다. 출현분류군은 가두리 예정지와 기존 가두리 해역에서 각각 26종류와 15종류이었고 총 개체수에서는 각각 7,702 개체/10$10\;cm^{2}$와 432 개체/$10\;cm^{2}$를 보여 기존 가두리 양식장에서 출현종류수와 서식밀도에 있어서 낮은 값을 보였다. 선형동물 (Nematoda)이 두 해역 모두에서 가장 우점하였고 다음으로 우점하는 육질편모충 (Sarco-mastigophora)과 함께 전체 출현개체수의 약 $90\%$를 차지했다. 퇴적물 깊이에 따른 현존량을 보면 표층 ($0\~1\;cm$)에 가장 높은 밀도로 서식하고 있었으며, 장두도에서는 퇴적물의 깊이에 따라 현존량이 서서히 감소하는 경향을 보인 반면, 저도의 기존 가두리지역에서는 퇴적물의 깊이에 따라 현존량이 급격히 감소하는 경향을 나타냈다. 저서환경 오염의 지수인 N/C 값 (nematodes/harpacticoid copepods ratio)는 기존 가두리지역인 저도에서 장두도보다 약 2배 정도 높은 값을 보여 유기물 함량이 높은 저도에서 선형동물의 상대적인 비중이 높음을 보였다. 또한 유기물오염에 민감하게 반응하는 Kinorhyncha를 이용하여 또 다른 저서환경 오염지수로 N/K 값 (nematodes/kinorhynchs ratio)을 처음으로 사용하였다. 그 결과 양 해역의 N/K 값은 N/C 값과 같은 경향을 보였다.

• 수산해양기술연구
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• 제56권2호
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• pp.83-93
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• 2020

In fisheries, the importance of designing efficient fish cages is being emphasized as aquaculture has become more production than capture fishing. Particularly, the gravity cage system is one of the popular fish cage system in Korea. Currently, gravity cages of various shapes and sizes are being widely designed and installed in offshore and inland seas. The cage is subject to external forces, such as currents and waves, and the shape of the structure and tension on the ropes changes according to these external forces. Thus, it is important to accurately calculate these dynamic behavior, including the external forces and tension on the structure during the design stage. In this study, three types of cage systems with an equal internal volume of 8000 ㎥ were analyzed using mass-spring models and their behavior was interpreted through simulations. These simulations were used to analyze the behavior and tension of the ropes in response to currents and waves to aid in the selection of individual cage sizes for a given total volume. The numerical calculation results indicate that depending on the flow rate, the most resistant system is System 1, which has eight strays, and System 2 and System 3 have 69.4% and 54.8% of the resistance of System 1. Further, total resistance increased as the number of cages increased for all flow rates.

• 수산경영론집
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• 제52권2호
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• pp.33-54
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• 2021

This study is aimed to analyze the economic feasibility of yellowtail culture using the copper alloy net cage in Gyeongsangbuk-do. First of all, in order to evaluate the copper alloy net cage on yellowtail culture, I review the trend on the yellowtail culture industry and research the concept of copper alloy net cage. The copper-alloy net cage is now recognized as an advantages of its system stability, recycling, antibiosis and food safety. The results were summarized as follows: first, there was significant meaning of the profit model of yellowtail culture by the price difference. Second, I analyzed in the economic feasibility of yellowtail culture using the copper alloy net cage, internal rate of return (IRR) was 51.58%, a benefit-cost ratio was shown to be 2.27 and net present value (NPV) was 1,087,337 thousand won, which indicates the economic feasibility of yellowtail culture using the copper alloy net cage is profitable. Finally, in order to improve the economic valuation, it is necessary to focus more on the developing of technology and cost reduction strategy on the copper alloy net cage.