• 수산경영론집
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• 제48권3호
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• pp.61-74
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• 2017

This study is aimed to analyze the change of chinese fishing vessels' entry into the East Sea off North Korea and suggest directions for countermeasures. Based on the real landing data in China, Chinese fishing vessels' squid catch volume and value in the East Sea off North Korea are estimated. Results show that at least 205 thousand tons of squid was caught by Chinese fishing vessels in 2014. If the catch amount is calculated by the unit price per kilogram at the same year in Korea, it would be 556.3 billion KRW. As the UN sanctions become stricter with the recent resolution 2371 passed, Chinese fishing vessels' entry may increase in the future to compensate decreased seafood supply from North Korea. Even though there are not many options left for Korea to decrease the impact of Chinese depletive fishing, the study suggests countermeasures such as strengthening cooperative crack down on the Chinese illegal fishing vessels in Korean waters; increasing cooperation with UN member countries to incorporate banning the trade of fishing rights in the next UN sanctions; establishing regional fisheries management organization and managing migratory species with China and Japan cooperatively in the long term.

• 한국물환경학회지
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• 제28권1호
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• pp.109-114
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• 2012

In this study, both sedimentation and thickening experiments were conducted for residuals produced from an advanced water treatment plant for more accurate and practical design of residual treatment train. In order to design a backwashed residual sedimentation basin (SRSB) in the filter backwash water recycle system, two kinds of backwash waters, one from sand filter (SFBW) and the other from GAC adsorption bed (GACBW), were separately collected and their surface loading rate measured. In addition, in order to design a gravity thickener, batch thickening tests were conducted for concentrated residuals taken from sedimentation basin and their limiting solid flux ($SF_{L}$) measured. From the experimental results and consideration of the seasonal characteristics of the residual, surface loading rate of $70m^{3}/m^{2}{\cdot}d$ was proposed as a design parameter for SRSB and solid loading rate of 20 kg $TS/m^{2}{\cdot}d$ was proposed as a design parameter for gravity thickeners. Finally, the material mass-balance was made for the design of each unit process in the residual treatment train.

• Ocean and Polar Research
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• 제23권3호
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• pp.305-310
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• 2001

This paper describes a floating fish reef technology for enhancement of fisheries productivity in the muddy areas. The floating fish reef was composed of main fish cage, anchor rope and concrete anchor blocks. Main fish cage was made up of 12 steel buoys measuring 0.37m in diameter and 1.5m long, polyethylene (PE) netting and circular steel rings. Each steel buoy had buoyancy of 110kgf. The size of main fish cage was 1.96 m in diameter and 3.75m in length. Monitoring on its durability was made for eight months after installation. The steel buoys fixed on main fish cage and nettings were observed to be kept safely. The wet weight of fouling organisms per unit area$(m^2)$ was 26.6kgf after eight months. Reduction in the cross-section of steel buoys and circular steel rings of main fish cage were not found. In addition, any cracks on the concrete anchor blocks were not observed.

• Fisheries and Aquatic Sciences
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• 제6권1호
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• pp.34-40
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• 2003

Three panel trammel nets were made illegal for the brown shrimp (Penaeus japonicus) or fishes by Korean fisheries law while trammel nets for fleshy prawn in the West sea remained legal. In this study a single panel tangle net with vertical loop lines rigged between the float line and sinker line was specially designed to catch brown shrimp. This net was developed for the first time after observation of the brown shrimp behaviour when reacting to a net in an observation tank. In field experiments these single tangle nets were compared with the traditional trammel nets in the coastal waters of the Keoje area. The mean number of the brown shrimp for 53 fishing operations was 1.13 per unit panel of the single tangle nets when fitted with the vertical loop lines. This was $84\%$ of the mean catch of 1.36 achieved with the trammel nets. These results of fishing experiments using single tangle nets in the field revealed a high fishing efficiency for the brown shrimp and showed little difference from trammel nets. The size of the brown shrimp or number of by-catch was not different between single tangle nets and trammel nets.

• 한국해양바이오학회지
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• 제3권1호
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• pp.31-37
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• 2008

Off the 1,572 km long coastline of Namibia lies known as the Benguela upwelling system, a very rich source of marine life supporting traditional and modern forms of fishery. Commercial fishing and fish processing is one of the fastest-growing sectors of the Namibian economy in terms of employment, export earnings, and contribution to GDP. The fishing industry has grown to the extent that it is currently Namibia's second biggest export earner of foreign currency after mining (90% of national output is marketed for export). In 2005, Namibia harvested about 552,164 tonnes of fish. The final value of processed products (export value) that year was around US$ 376.0 million. Besides the marine captured fisheries, Namibia also has a small but vibrant aquaculture sector. Inland captured fisheries exist in the north-east and north-west of Namibia where as commercial freshwater aquaculture of tilapia and catfish is also undertaken. The inland fisheries are mainly subsistence based and typically labour intensive, with low catch per unit effort. However the subsistence fisheries from these regions play a significant role in the lives of rural community. The domestic market for marine fish products is extremely limited due to the small size of the population (2 million). The fishing industry is a source of considerable employment for many Namibians. Huge potential to increase production exists in Namibia, unpolluted high quality marine waters, high natural primary productivity of the seawater, availability of inexpensive fish by-products from established fish processing sector for inclusion in wet aqua-feeds and well-established processing, packaging and marketing systems due to the marine capture fisheries that can be adopted for aquaculture purpose.

• 한국수산과학회지
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• 제54권5호
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• pp.769-781
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• 2021

Given data about the annual fishery yield of the common squid Todarodes pacificus, and the catch-per-unit-effort (CPUE) data from multiple fisheries from 2000-2018, we applied a Bayesian state - space assessment model for the squid population. One of our objectives was to do a stock assessment, simultaneously incorporating CPUE data from the following three fisheries, (i) large trawl, (ii) jigger, and (iii) large purse seine, which comprised on average a year about 65% of all fisheries, allowing possible correlations to be reflected. Other objectives were to consider both observation and process errors and to apply objective priors of parameters. The estimated annual exploitable biomass was in the range of 3.50×10⁵ to 1.22×10⁶ MT, the estimated intrinsic growth rate was 1.02, and the estimated carrying capacity was 1,151,259 MT. Comparison with available results from stock assessment of independently analyzed single fisheries revealed a large difference from the estimated values, suggesting that stock assessment based on multiple fisheries should be performed.

• Coupled systems mechanics
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• 제11권1호
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• pp.33-41
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• 2022

Quite often we have a lot of measurement data and would like to find some relation between them. One common task is to see whether some measured data or a curve of known shape fit into the cumulative measured data. The problem can be visualized since data could generally be presented as curves or planes in Cartesian coordinates where each curve could be represented as a vector. In most cases we have measured the cumulative 'curve', we know shapes of other 'curves' and would like to determine unknown coefficients that multiply the known shapes in order to match the measured cumulative 'curve'. This problem could be presented in more complex variants, e.g., a constant could be added, some missing (unknown) data vector could be added to the measured summary vector, and instead of constant factors we could have polynomials, etc. All of them could be solved with slightly extended version of the procedure presented in the sequel. Solution procedure could be devised by reformulating the problem as a measurement problem and applying the generalized inverse of the measurement matrix. Measurement problem often has some errors involved in the measurement data but the least squares method that is comprised in the formulation quite successfully addresses the problem. Numerical examples illustrate the solution procedure.

• 한국해양학회지
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• 제24권3호
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• pp.157-164
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• 1989

서해 금강하구 오식도 부근의 조간대와 조하대역에서 식물플랑크톤의 종별 양적 분포 및 일차생산력과 bacterioplankton(부유박테리아)의 균체수 분포를 1987년 8월부터 1988년 7월 사이에 11회에 걸쳐 조사하였다. 규조류 102종을 포함하여 식물플랑크톤은 총 121 종류를 확인하였고 양적으로는 15-5451 cells/ml 범위였는데, 이들의 시공간적 변화에는 조간대와 조하대의 환경특성 차이가 잘 나타나 있었다. 식물플랑크톤의 일차생산력 (Piopt, mgC/$m^3$/hr)은 0.6-27.32의 범위로서 현존량이 높은 시기와 일차생산력이 높은 시기가 반드시 일치하지는 않았다. 춘계 대번식 후의 4월 조간대역 정점에서는 Piopt와 amylolytic bacterioplankton의 균체수가 모두 극히 낮았다. 정점간 Piopt 비율의 변화에도 역시 조간대와 조하대 역의 환경차이가 잘 나타났다. 식물플랑크톤 현존량과 총 종속영양세균(heterotrophic bacterioplankton) 및 생리적 특성별 bacterioplankton군, 즉 전분분해(amylolytic), 단백질분해(proteolytic) 및 지방분해(lipolytic) 세균과의 관계에는 뚜렷한 경향성이 나타나지 않았으나, 강우량이 집중된 7, 8월에는 각 bacterioplankton의 균체수가 매우 높은 반면 식물플랑크톤의 현존량은 연중 가장 낮아 외래유입(allochthonous) 유기물의 양이 많았음을 시사하였다. 측정된 총 종속영양성 bacterioplankton 및 생리적 특성별 bacterioplankton의 균체수와 Piopt 와의 관계로부터 조사해역에 유입되는 외래성 유기물의 함량 특성을 추정할 수 있었다. 즉, 전분분해 세균과 지방분해 세균은 Piopt와 높은 상관성 (각기 $R^2$값이 0.84 및 0.70) 을 보여 이들이 수중 식물플랑크톤(autochthonous)의 유기물 생산과 직접 관련됨을 알 수 있었고, 단백질분해 세균이나 총 종속영양세균의 분포는 Piopt와 뚜렷한 상관성이 없어 외래유입 유기물 (강수유입, 저층으로부터의 resuspension 등)에 의해 크게 영향을 받는 것으로 판단되었다. 회귀 직선의 기울기로부터 조사 역에서는 Piopt 1mgC/$m^3$/hr 증가당 전분분해 세균이 $9.0{\times}10$ cells/ml, 지방분해세균은$8.0{\times}10$ cells/ml 씩 균체수가 증가하는 것으로 계산되었다.

• 한국물환경학회지
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• 제27권6호
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• pp.784-793
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• 2011

Activities on golf courses are believed to contribute to the degradation of water quality in receiving waters due to the excessive use of farm chemicals including fertilizers and pesticides. The objective of this study was to collect basic data that could explain the characteristics of non-point source (NPS) pollution discharged from a golf course. Twenty seven water quality monitoring was conducted at a golf course during the rainy season of 2008 and 2009. The results indicated that the ranges of the Event Mean Concentration (EMC) at the golf course were $BOD_5$ 1.8~11.3 (ave. 5.6) mg/L, $COD_{Mn}$ 19.2~51.4 (ave. 39.6) mg/L, TOC 11.0~31.0 (ave. 16.8) mg/L, TN 1.545~16.098 (ave. 5.623) mg/L, TP 0.230~4.528 (ave. 1.525) mg/L, and SS 2.2~57.3 (ave. 10.1) mg/L. The unit loads of the golf course estimated were $BOD_5$ $3.35kg/km^2/day$, SS $6.43kg/km^2/day$, $COD_{Mn}$ $30.00kg/km^2/day$, TN $4.04kg/km^2/day$, TP $1.14kg/km^2/day$, and TOC $12.16kg/km^2/day$. Golf courses are currently classified as a grass field in which the unit loads are different from golf courses. Therefore, it was recommended that golf courses need to be separated from the grass field when the surveys and modelings for Total Maximum Daily Load (TMDL) development and the evaluation of TMDL implementation were performed.

• 환경영향평가
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• 제16권1호
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• pp.69-77
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• 2007

This study has been conducted to assess blackish-water phenomena in Dam reservoir. To searching for the reason, we survey physical changes in reservoir and analyze metal and organic content in particulate materials and water. The blackish-water phenomena in lake A are occurred with turbidity increases in turnover season irregularly. It was reported on 6 Jan. 2005 weakly and the water column mixed with 35~40m depth and water temperature shows $7^{\circ}C$. The turbidity of AD and AM site increased up to 20NTU. Especially, AN site shows 27NTU, such a result makes that Dam manager conclude it to blackish-water phenomena. The results of sequential extraction analysis show that over 80% of Al, Cr and Fe is existed in residual form in sediment. On the other hand, the most part of Mn shows exchangeable and carbonates form, which have a good possibility of release to water column. Mn contents in pore waters of the sediment samples are also found to be ~4 times higher than Fe contents. The metal contents in pore water of different dam sites are in order of AN (Fe: 9.98, Mn: 40.6) > AD(8.33, 37.5) > DD(1.91, 2.55). According to the results of extracted organic materials from sediment, humic substances is occupied with over 85% in total organic carbon including 23~45% of humic acid (HA) and 0.9~8.5% of fulvic acid (FA). However, HA content in pore water is not detectable while FA contents, acid-soluble humic fractions is higher than that of sediment(10~15%). which indicating that FA is a main humic components affecting water color. The color unit per DOC of FA in pore waters of different dam sites are found to be higher in lake A than lake D. From the results, it could be suggested that blackish-water phenomena of lake A are mainly arise from higher concentration of Mn and water soluble organic fractions (e.g., FA) released from sediments as well as the strength of turnover in Dam reservoir.