• 한국수산과학회지
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• 제28권6호
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• pp.708-719
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• 1995

This study is to estimate abundance of the Chesapeake Bay blue crab stock. Using 823 dredge tows which were conducted during the 1991 winter survey, blue crab abundance was estimated on the basis of newly developed methods which account for unequal dredge tow distances, size- and sex-specific heterogeneous overwintering spatial distributions, wintertime exploitation, the time period of quasi-hibernation, and dredge capture efficiency. The estimate of total abundance before correction by gear efficiency was 131.8 million crabs $(95\%\;C.I.\;=\;118.2\;million\;crabs\;to\;145.4\;million\;crabs),$ Dredge capture efficiency was estimated to be 0.474. Thus, the estimate of total abundance was calculated as 278.1 million crabs after correction by the efficiency factor.

• 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.

• 한국수산과학회지
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• 제26권4호
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• pp.369-379
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• 1993

1992년 동계에 췌셰픽만의 꽃게자원에 대하여 예망을 사용한 연속채집법에 의한 어획 효율성을 조사하였다. 일반선형모델 분석에 따르면 26회에 걸친 야외시험 결과 어획효율성은 저질이나 수심, 사용된 조사선박에 따라 통게학적으로 유의한 차이가 나타나지 않았다. 예망효율(즉, 어획율)은 Leslies방법과 단순히 개조된 방법 등의 두 방법을 사용하여 추정하였다. 평균 어획율은 0.26 (표준오차:0.03)으로 추정되었는데 이는 한번의 예망을 사용하여 채집장소에 존재하고 있는 꽃게 가운데 단지 $26\%$($95\%$ 신뢰한계 : $20{\sim}32\%$)를 잡을 수 있다는 의미이다. 예망효율은 꽃게의 밀도가 증가함에 따라 지수적으로 감소하였다.

• 한국수산과학회지
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• 제22권4호
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• pp.189-195
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• 1989

본 연구는 1982년 8월부터 1986년 2월 까지 5년에 걸쳐 계절별로 한반도에 인접한 황해의 저서다모류를 대상으로 정량 채집하여 다모류의 중요성과 종조성을 파악하였다. 다모류의 비중은 전 저서동물군 중에서 가장 높은 $35.1\~46.4\%$의 조성률을 나타내었고, 생체양에 있어서는 극피동물이나 연체동물군이 우점군으로 나타났으나 그들의 계절적 변화 폭이 일정하지 않고 매우 다양했다. 채집도구에 따른 다모류의 비중은 드레지(dre-dge)를 사용할 경우 채이기(grab)의 경우보다 약간 낮은 조성률을 나타내었다. 이는 드레지의 경우가 훨씬 더 퇴적물의 표층부분만을 예인하기 때문이었으며 다모류의 조성률도 다소 낮은 경향을 보였다. 본 연구기간 중 출현한 다모류는 모두 141종으로 나타났으며 이 해역에서의 대표종은Spiophanes bormbyx, Ampharete arctica, Geniada maulata, Nephtys caeca, Nothria iridescens이었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.28-41
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• 2009

We know the several construction methods for underwater tunnel, but properly submerged concrete box type tunnel was mostly good structure stability and mostly shot length of tunnels. Submerged box type tunnel was buildup the unit segments in dry dock or ship yard by 10 to 20meters. The submerged box was composed with segments was join each together. It was installing the gate and waterproofing the coupling the front hull of a box. The complete submerged box rise up to the surface water, tow in the submerged box by tugboat, going to the destination of tunnel construction site. Beforehand dredge up soil at the bottom of a underwater, sinking the submerged box, connection together complete submerged box in underwater. The research and development ILM tunneling method is receiving careful study. Biggest weakness in submerged concrete box type tunnel was pressure waterproofing, box to box connecting, complete submerged boxes navigation and installation, after operation the submerged tunnel and management concrete box structure. It was positive evidence in submerged concrete box type tunnel. We make a practical application of the principle "the ILM tunneling method in underwater construction methods."

• 한국농공학회논문집
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• 제59권4호
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• pp.43-52
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• 2017

This study analyzed pore water pressure, earth pressure and settlement through laboratory model tests in order to suggest the effective remodeling method in the case of reinforcing the upstream and downstream slope of deteriorated reservoirs that has no cores and filters or is not functional. The method of remodeling the upstream slope using dredge soil is first prevent seepage by installing the core, and the leakage water can be rapidly discharged through a filter installed on the downstream slope. Therefore, it is considered a highly efficient method of remodeling that reduces piping phenomena and increasing the storage capacity of the reservoir. The variation of earth pressure without the core and filter was greater than with it, while the change largely showed in the upstream slope, the downstream slope did not show any significant changes. The remodeling method of the downstream slope with the core appeared differently pore water pressure depending on the presence of the vertical and horizontal filters. In the upstream slope, the pore water pressure rises sharply, the base and middle gradually increased, and the downstream slope appeared small. The pore water pressure of embankment with a vertical and horizontal filter will be smaller than without it. The remodeling of deteriorated reservoir that does not have the function of the filter, the vertical filter must be installed in a position that is higher than the expected seepage line by removing portions of the downstream slopes. Since the horizontal filter is an important structure that provides stable drainage during an earthquake or concentrated leak, it is necessary to examine any change in the seepage characteristics depending on the filter intervals via three-dimensional finite element analysis, and it should be connected to the tow-drain to reduce the possibility of the collapse of the reservoir.