• 수산해양기술연구
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• 제43권4호
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• pp.355-361
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• 2007

A giant jellyfish (Nemopilema nomurai), which is presumed developing in the East China Sea, is recently one of major issues in the Northeast Asia region due to its fatal damage to the fishery. The biomass estimates have generally been conducted by trawl sampling and sighting survey methods. The biological research is also needed to clarify such environmental origin or diurnal migration patterns. While trawl sampling or sighting survey methods are effective to investigate its density estimates in its distributed community of near bottom or surface, they have a problem in investigation on the vertical distribution of jellyfishes. In this case, an echo sounding detection would have an advantage to survey it more extensively and effectively. This trial was conducted to observe the vertical distribution of giant jellyfish, where thermocline strongly formed, during mooring at each station of the East China Sea and southern coastal area using acoustical and optical methods. By the results, they were observed to exit and move at the water column under the thermocline using the optical camera and echo sounder system, and the information was analyzed to find out the acoustical sound scattering characteristics relatives to 120kHz frequency. These results can be utilized effectively to estimate the vertical distribution and biomass of Giant jellyfish with comparing results from trawl sampling and sighting survey methods, hereafter.

• 수산해양기술연구
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• 제56권2호
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• pp.147-154
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• 2020

The questionnaire survey was carried out to collect basic data to identify the cause of the risk that did not appear in the current data provided by the fishermen's occupational accidents of the National Federation of Fisheries Cooperative (NFFC) to the onsite specialist, such as a fishing master, chief engineer and fisher in stow net fishing vessel from June to July 2018. The results are as follows. A total of 134 cases were surveyed, including 53 cases in Yeosu, 44 cases in Mokpo, 30 cases in Boryeong and 7 cases in Gunsan. Approximately 60% of the respondents on board the stow net fishing vessel were more than 20 years old, and the boarding experience was seasoned and suitable for the respondents. In the 4M analysis by safety accident factor during fishing work, the mechanical factors included 51 cases (25.0%) of decrepit equipment or poor maintenance and 49 cases (24.0%) of systemic error of fishing equipment. The environmental factors exhibited 71 cases (33.5%) of poor communication by mixed manning of foreign fishermen and 63 cases (29.7%) of poor environment such as heavy weather etc. The human factors showed 78 cases (37.3%) of personnel's carelessness and 45 cases (21.5%) of unskillfulness of operating net and haulers. The management factors exhibited 59 cases (32.1%) of work practice of poor safety precautions and 56 cases (30.4%) of inadequacy of education on hazard factor. The results are expected to contribute to the creation of a safe operating environment for stow net fishery, such as a fisher boarding a stow net fishing vessel, enabling the analysis of major causes of working safety accidents by cause.

• 한국양식학회지
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• 제19권3호
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• pp.178-182
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• 2006

이 연구에서는 해산어 초기 자어 사육 과정에서 자어가 섭이하는 로티퍼의 새로운 관찰 및 계수방법을 제시한다. 지금까지는 해산어 자어를 사육하면서 언제부터 로티퍼를 먹이로 이용 가능한지? 그리고 일령이 경과함에 따라 어느 정도 양의 로티퍼를 섭이하는지? 정확하게 분석할 수는 없었다. 왜냐하면 자어가 섭이한 로티퍼(몸통)는 소화기관내에서 소화되어 연구자가 관찰할 수 없었기 때문이다. 그러나 이 연구에서는 이러한 문제점을 해결할 수 있는 새로운 관찰 방법으로서 로티퍼의 저작기(trophi)를 이용하는 방법을 제시한다. 로티퍼는 각 개체마다 한개의 저작기를 가지며 이 저작기는 해산어 자어의 소화기관내에서도 소화되지 않고 그 형태를 유지한다. 따라서 이 연구 결과에 의하면 자어의 소화기관내의 저작기를 관찰하여 계수하는 방법(RTCM; Rotifer Trophi Counting Method)을 이용하여 로티퍼를 최초로 섭이하는 일령은 물론 자어의 일령이 경과함에 따른 포식 로티퍼 개체수를 정확하게 분석할 수 있다.

• 대한조선학회논문집
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• 제52권1호
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• pp.19-24
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• 2015

The economic efficiency for fishery products can be related to their freshness and the quality. In order to freshly storage the product, freezing equipment system is necessary for fishing vessels. For this purpose, the horizontal plate freezer (HPF) is mostly used. In this research, our major objective is to improve the freezing performance of the HPF. Therefore, it is important to analyse the relationship between the shape of channels and the cooling temperature of the HPF. In order to save calculation time while checking the trend analysis between shape and performance, we used scaled models, and evaluate the cooling temperature of full scale model based on trend analysis results. The produced HPF in domestic was used, and the same operating conditions are considered. Based on this paper, the future research will be a comparison and verification through the experiments.

• 수산경영론집
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• 제36권1호
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• pp.139-153
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• 2005

Marine fish aquaculture has been introduced on the East sea since 1964. The production volume of the marine aquaculture has been increasing drastically since 1990 with the technological improvements and the introduction of new species. However, the increasing costs of feed, seedlings and medical supplies and the decreasing prices due to the increase in the imports and domestic production have decreased the profits in the aquaculture business. Futhermore, the damage from the natural disasters such as red tides and typhoons has accelerated the exit from the business. Even though managing abilities to overcome the business crisis caused by the above factors are required, business managers based on the small scale family businesses do not have enough managing abilities to deal with the difficulties in the business. On the other hand, advanced countries in the marine aquaculture such as Norway have reached the stage where the managing abilities of marine aquaculture are similar to those in the manufacturing industry. And the number of large scale aquaculture farms with developed technologies and advanced marketing strategies in those countries is increasing. Considering that the marine aquaculture in Japan under the similar fishery systems of Korea has developed the state-of-the-art management skills or lead to large scale management, it is difficult to expect the decrease in the production costs under the small scale family business in Korea and this will lead to the decreasing competitive advantage over the imported seafood. Therefore marine aquaculture in Korea needs to increase the economy of scale to acquire the competitive advantage. This study addresses the possibility of introducing the large scale aquaculture system in Korea by analysing the factors and process of leading to large scale businesses in the aquaculture in Japan.

• Journal of the Optical Society of Korea
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• 제20권5호
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• pp.547-556
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• 2016

A fishing lamp is the instrument for attracting distributed fish to a certain place, and is the lighting system mainly used in fishery. In the inshore fishing, most fishing lamps are used for squid and hairtail jigging fishing, and the light source of the fishing lamps mainly used is metal halide with 1.5 KW in electric power consumption. We will analyze the irradiance distribution according to depth because squid is attracted towards light. To analyze irradiance distribution by such fishing lamps, data for seawater Type-II among the seawater types defined in 1976 are applied to East Sea. However, the Type-II data have limitations in analyzing precise seawater transmission characteristics, due to insufficient information on deep seawater. This paper analyzed the irradiance distribution of fishing lamps using the measurement of transmission characteristics in the seawater in East Sea up to 100 m underwater instead of Type-II data, which is not sufficient for transmission. A compensation factor was drawn between the actual measurement data and Type-II data through seawater transmission characteristics simulation.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 춘계종합학술대회
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• pp.391-396
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• 2005

한국 연안 전 해역에 걸쳐서 매년 적조생물이 발생 한다. (1995년부터). 남해 중부 및 동부해역은 상습발생 지역이다 (7, 8월). 기상인자(기온, 수온, 강수량, 일사량, 일조시수, 바람)는 적조형성에 기여하며, 특히 수온 (기온)은 적조발생의 제한 인자로 작용한다. 수온 15$^{\circ}$C가 되는 일을 기점으로 적조발생에 소요되는 시간은 78${\sim}$104일 정도 걸리며, 누적일조시수, 누적수온, 누적강우량의 비교로부터 적조발생 해역을 구분할 수 있다. 즉, 남해중부 및 남해동부 해역은 고밀도 적조발생 해역이며 남해서부 해역, 동해남부 해역은 저밀도 적조발생 해역이다. 동해남부 해역을 제외한 나머지 해역은 수온 24.5${\sim}$25.5$^{\circ}$C의 범위에서 1000mg/l 이상의 밀도를 보이는데, 적조생물이 발생하면 대체로 수산피해를 가져다주는 적조경보의 범주에 든다. 위성원격탐사 기술로부터 우리나라 연근해 적조발생 해역 해황특성과 적조분포 상호간의 관계성으로부터 적조의 머무름과 이동은 냉수대의 발달 및 소멸 그리고 북상난류의 흐름과 밀접한 관계가 있음을 알 수 있었다. 또한 식물성플랑크톤의 농도의 변화를 이용하여 적조분포 해역의 감지가 위성위격탐사 기술로 가능하였다. GIS 기술을 통한 적조정보관리시스템의 구축으로 적조정보를 통한 공간분석이 가능하게 되었다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 Asia Navigation Conference
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• pp.105-114
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• 2006

Together with the trend of enhancement in domestic industrial development and economic progress due to import and export, the demand for construction of the roads, bridges, especially port facilities, and several coastal protection and ocean structures is increasing rapidly. MOMAF of Korean Government is driving construction of 9 new ports and renovation of the existing fishery ports. Among these structures most of bridge base, wharves, dolphins, quays, and jetties are being newly built of steel or concrete pile. As the base, supporting bulkheads, and piles are underwater after construction, it is difficult to figure out the status of structures and not enough to get maintenance and strengthen the structures. Every year, moreover, these works suck the government budget due to higher incomplete maintenance expense for protection from corrosions of structures and increased underwater construction period. for the purpose of cutting down the government budget, it is necessary to extend the life cycle of the existing structures. We developed a new method for maintenance of submerged structures near the waterline by allowing dry work environment with the floating caisson. The method shows easy to move around the working area and handle. It also showed not only a significant reduction of maintenance expenses and time for anti-corrosion work but also better protection. This will be a milestone to reduce the maintenance and construction expenses for the shore and water structures.

• 수산해양기술연구
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• 제50권3호
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• pp.396-406
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• 2014

Shrimp beam trawl fishery is one of the important coastal fisheries in Korea. It has a regulation to the length of beam (8m) and wing net (7m) of shrimp beam trawl that has been used in the district of Junlanam-do and Gyungsangnam-do. This regulation was made in relation to the size of shrimp beam trawler of 3-ton class at that time. Now the shrimp beam fishing vessel has a limit not greater than 5 tons in gross ton. Recently, with improvement of fishing industry and fishing vessel fishermen asked the expansion of the length of beam and wing net, therefore it is necessary to investigate the effect of lengthening the beam and wing net length. Three different beams (8m, 10m and 12m in length) and three different wing net (7m, 10m and 13m in length) were made and the experiment was conducted near Narodo of Goheng by two fishing vessels of 4.98 and 4.88 tons in gross ton between June 2011 and October 2012. When the length of wing net was increased from 7m to 10m and 13m, the relative catch ratio in total biomass was increased 25% and 79% for shrimp, (17% and 22% in total), respectively. And when the beam length was increased from 8m to 10m and 12m, the relative catch ratio was increased 35% and 84% for shrimp, (21% and 37% in total), respectively. The force exerted to the iron guide of inhauler's with the beam length of 8m was about 30% greater than that with the beam length of 10m when hauling the shrimp beam trawl net.

• 한국수산과학회지
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• 제31권1호
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• pp.63-70
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• 1998

새우에 일정량의 식염, 아질산염, 질산염 및 아스코르브산을 첨가하여 숙성시키면서, NA생성에 미치는 영향에 대해 조사한 결과는 다음과 같다. pH는 담금직후 8.1에서 숙성 110일 후 6.5로 산성화되었다. TMAO 질소는 숙성중 감소한 반면, TMA 및 DMA질소는 증가하였다. 아질산염 첨가구는 숙성중 NDMA함량이 증가하였고, 아스코르브 산첨가구는 NDMA생성이 억제되었다. 모델계실험 결과, 새우젓의 니트로소화 최적 pH는 3.5이었고, 아스코르브산은 NDMA생성을 크게 억제시킨 반면 thiocyanate는 촉진시켰다. 본 실험 결과, 새우젓 자체에는 NDMA가 거의 검출되지 않았으나, 질산염이나 아질산염의 함량이 많은 물질과 함께 섭취된다면 위내에서 NDMA가 생성될 가능성이 충분한 것으로 판단되었다.