• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.3
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• pp.63-71
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• 2003

This study investigated about the seasonal variation of pollutant loads flowing into the Yeong-il bay from constructing Tank model which is the simulation model to evaluate the daily river discharge and pollutant load in the Hyeong-san river watershed. The estimated annual average river discharge of Hyeong-san river flowing into Yeong-il bay is about 878.34×10/sup 6/㎥/year which is about 73% of annual average of total precipitation in Hyeong-san river watershed. The annual average of pollutant load flowing into Yeong-il bay was estimated each 15.11 ton-COD/year, 23.24 ton-SS/year, 10.65 ton-TN/year, and 0.54 ton-Tp/year. For the seasonal variation of pollutant loads, it was tended as increasing of river discharge as increasing of inflow pollutant loads at June and July of summer and October of autumn. The main source of pollutant loads was found to be the Pohang city and Pohang industrial complex which are located near the mouth of Hyeong-san river. Therefore, for effective water quality management of Yeong-il bay, the counterplan to reduce pollutant loads from the main source of pollutant loads is required.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.4
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• pp.83-92
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• 1993

This paper describes structural safety assessment techniques against crygenic temperature to design MRV type B LNG tank system. The following items are detail with in detail. (1) Leakage estimation of LNG through the propagating clacks at tank plate was performed and design of the range of catch basin(2ndary barrier) was followed to ensure the safety of ship structures against leaked LNG. (2) Temperature distribution analysis for cargo hold and skirt system was carried out using the steady state heat transfer analysis model for spherical LNG tank system. (3) Thermal stress distribution of skirt and tank system was calculated, where very stiff thermal variation was shwn through item(2) analysis.

• Journal of Ocean Engineering and Technology
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• v.29 no.4
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• pp.291-299
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• 2015

A variety of inner baffles are often installed to reduce liquid sloshing and prevent tank damage. In particular, a porous baffle has a distinct advantage in reducing sloshing by changing the natural periods and dissipating the wave energy in a tank. In model tests, porous baffles with five different porosities were installed vertically in a liquid tank under sway motion. The free surface elevations and pressures were measured using an image processing technique and a pressure gage for various combinations of baffle's porosity and submergence depth, and tank's amplitude and period. The experimental results were in good agreement with the analytic solutions (Cho, 2015), with the exception of a quantitative difference at resonant periods. The experimental results showed that the sloshing characteristics in a tank were closely dependent on both the porosity and submergence depth of the baffle, and the optimal porosity existed near P = 0.1275.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.3
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• pp.1-8
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• 2009

The objectives of this study are to apply univariate search and genetic algorithm to tank model, and compare the two optimization methods. Hydrologic data of Baran watershed during 1996 and 1997 were used for correction the tank model, and the data of 1999 to 2000 were used for validation. RMSE and R2 were used for the tank model's optimization. Genetic algorithm showed better result than univariate search. Genetic algorithm converges to general optima, and more population of potential solution made better result. Univariate search was easy to apply and simple but had a problem of convergence to local optima, and the problem was not solved although search the solution more minutely. Therefore, this study recommend genetic algorithm to optimize tank model rather than univariate search.

• Journal of Korea Water Resources Association
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• v.36 no.5
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• pp.851-861
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• 2003

Snow accumulation and snow melt was simulated and included in the computation of the watershed runoff for Soyanggang Dam and Chungju Dam. A modified Tank Model was used for the simulation, which has three serial tanks and a pulse response function. The model parameters were estimated through the global optimization method of Shuffled Complex Evolution-University of Arizona (SCE-UA). A watershed was divided into four zones of elevation. The temperature decrease of the zones was a rate of -0.6$^{\circ}C$/100m. Almost all precipitation from December to February become accumulated as snow, and then the snow melts and runs off from March to April. The average runoff with snow melt was greater than the average runoff without snow melt during the period from March to April. The improved amount from snow melt simulation was about one fifth of the observed one for Soyanggang Dam. The increased amount for Chungju Dam was about one fourth of the observed average runoff during the same period. Although the watershed runoff was simulated including snow melt, it was less than the observed one for both of the dams.

• Journal of Korea Water Resources Association
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• v.32 no.3
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• pp.265-279
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• 1999

In this study, one of the techniques on the extension of low flow series has been developed, in which the daily streamflows were simulated by the Tank model with the input of extended daily rainfall series which were stochastically generated by the Markov chain model. The annual lowest flow serried for each of the given durations were formulated form the simulated daily streamflow sequences. The frequency of the estimated annual lowest flow series was analyzed. The distribution types to be used for the frequency analysis were two-parameter and three-parameter log-normal distribution, two-parameter and three-parameter Gamma distribution, three-parameter log-Gamma distribution, Gumbel distribution, and Weibull distribution, of which parameters were estimated by the moment method and the maximum likelihood method. The goodness-of-fit test for probability distribution is evaluated by the Kolmogorov-Sminrov test. The fitted distribution function for each duration series is applied to frequency analysis for developing duration-low flow-frequency curves at Yongdam Dam station. It was shown that the purposed technique in this study is available to generate the daily streamflow series with fair accuracy and useful to determine the probabilistic low flow in the watersheds having the poor historic records of low flow series.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.1
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• pp.74-83
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• 1995

To estimate the parameters of a mathematical model of fishes' swimming behavior, the behavior in a experimental water tank was observed and analyzed using the video monitoring system. The tank was equipped with vertical circulation system, and measured $3,500L\;{\times}\;1,500B\;{\times}\;1,000H\;mm$ at flow channel and $1,200L\;{\times}\;900B\;{\times}\;500H\;mm$ at observational part. Rainbow trout, salmo gairdnerii were used as experimental fishes. Their swimming behavior in the tank was observed by the monitoring system, and the positions of every individual were checked at 0.5 second intervals by the image processing of recorded pictures for 5 minutes. The mean swimming speed calculated from the time series data of positions of every individual ranged from 2.5BL cm/sec to 2.9BL cm/sec at the stagnated flow. The mean swimming speed of 10 individuals in a school increased according to the flow speed. The mean swimming depth ranged from 17 cm to 38 cm even though it changed irregularly at the stagnated flow and gradually became stable according to the increase of flow speed. In the present study, the mean distance of individuals from wall of the tank varied from 17.6cm to 21.4cm. The mean distance between the nearest individual varied from 0.4BL cm to 0.7BL cm when 10 individuals in a school were observed. The mean dimension of fish schools became enlarged in all directions according to increase in the number of individuals, and as flow speed increased the horizontal dimension of fish schools expanded while their vertical dimension decreased.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1012-1016
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• 2006

최근 오염총량관리제도를 위한 오염부하량의 관리문제가 대두되면서 이를 위한 수질분석의 중요성이 인식되고 있다. 그러나 시간적 변화를 가진 유입유량, 유입부하량 자료의 한계로 인하여 기준유량을 대상으로 하는 정적수질분석의 결과가 환경정책에 반영되고 있는 실정이며, 이는 하천유량의 변동과 강우 시 비점오염부하량을 무시한 지극히 제한된 분석에 국한되어 있다. 따라서 시간적 변화를 가진 동적수질분석의 결과가 정책에 반영되기 위해서는 자료의 확보가 우선이다. 본 연구에서는 월 별, 소유역 별 시계열 자료 확보를 위하여 합리적이고 사용이 용이한 방법을 제시하였다. 유출량의 경우, 기존의 비유량법과는 달리 저류효과를 고려한 토양수분 저류구조 Tank모형을 적용하여 장기간의 유출량을 산정하였고, 유출농도의 경우, 기존 인접유역의 동일 유달계수 적용과는 달리, 월 오염부하총량비와 유역오염부하 전달함수를 이용하여 월 별, 소유역 별, 수질변수 별 유출농도를 산정하였다. 산정된 유출량과 유출농도는 남강댐 상류유역 하천에서 WASP 모형을 가지고 동적수질분석을 하기 위하여 적용되었다. 그 결과 적절한 오염물질 농도곡선을 얻을 수 있었으며, 제안된 가정의 적용 가능성은 충분하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.264-268
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• 2008

미래 발생 가능한 수문 및 기상현상의 예측과정은 지식의 부족과 자연현상의 다양성으로 인해 불확실성을 포함하게 된다. 하지만 많은 예측들은 아직까지 확정적으로 제공되고 있으며, 결과적으로 예측결과의 불확실성 정도를 제공하지 못하고 있다. 앙상블 유량예측(ESP, Ensemble Streamflow Prediction)은 이러한 불확실성을 고려하여 수자원시스템의 의사결정에 있어 중요한 요소 중 하나인 유량예측을 수행할 수 있는 방법이다. 하지만 ESP의 결과는 기상자료, 유역 초기조건, 수문모형의 매개변수, 단순화된 수문모형에 의해 비교적 큰 불확실성을 포함하게 되며, 따라서 실제적인 현업에서의 사용을 위해서는 불확실성 정도를 줄이기 위한 사전 및 사후처리 과정이 요구된다. 본 연구에서는 국내에서 활용 가능한 기후 예보자료를 사용하여 앙상블 유량예측에 적용할 수 있는 사전처리 방안들을 검토하고, 국내에서 사후처리를 위해 적용되었던 최적선형 보정기법에 더해 다양한 기법들을 강우유출모형인 TANK모형의 모의결과 보정에 적용하였다. 사전 및 사후처리를 적용한 결과 기상자료와 유량예측과정에 존재하는 불확실성을 저감시키는 것이 가능하였다. 특히 사전 및 사후 처리가 동시에 적용되었을 경우 그 향상 정도가 단순히 각각의 방법에 의한 향상 정도를 합한 것보다 높게 나타날 수 있음이 확인되었다. 사전 및 사후처리를 동시에 적용한 경우 이수기에는 RPS(Ranked Probability Score) 평가방법 내에서 54%를, 홍수기에는 8%를 향상시키는 것이 가능하였다.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.15-21
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• 1996

Recently speed control system of the towing carriage have been modified by applying a personal computer in the Ship Model Towing Tank of Seoul National University. With this system the carriage speed could be controled precisely in coincidently with a prescribed speed diagram to evaluate the effect of slight towing speed fluctuation caused by some residual current or standing waves which have believed as trivial phenomena in the towing tank. It is found that the slight speed fluctuation of the carriage could lead to serious error in measurement of resistance test of a ship.