• 한국음향학회지
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• 제34권1호
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• pp.12-19
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• 2015

여름철 제주 남부해역에서 내부조석에 의한 음향특성 변화를 실측 자료와 모의실험을 통해 연구하였다. 이를위해 서귀포 인근 해역의 수심 80 m 내외인 두 정점에서 2009년 7월 27일과 28일에 걸쳐 25시간동안 한 시간 간격으로 수심별 수온을 측정하였다. 그 결과 조석에 의해 해수 상층부의 등수온선이 약 10 m이상 반일주기로 변하는 현상이 관측되었다. 이로 인한 음파전달손실의 시간적 변화를 확인하기 위해 음원을 수심 10 m에 두고 거리 3.8 km 떨어진 두 관측 정점 사이에서 음파전달을 모의하였다. 중심주파수 100 Hz인 1/3 옥타브 밴드의 경우 특정 수심 및 거리에서 반일주기가 지배적 이었으나 1 kHz의 경우는 반일주기 성분이 거의 나타나지 않고 복잡한 변화를 보였다. 음원에서 거리 2.8 km떨어진 지점에서 시간에 따른 전달손실 변화의 표준편차는 중심주파수 100 Hz의 경우 수심에 따라 최대 4.2 dB 였으며, 1 kHz의 경우 최대 3.7 dB인 것으로 나타났다. 탐지성능 60 dB를 고려한 탐지거리를 분석한 결과 두 중심주파수 경우 모두 반일주기 변화가 나타났으며 최대 1.0 km 미만의 변화를 나타냈다. 이러한 결과는 차후 제주 남부해역의 음향 특성 실험 및 연구 수행 시 전달손실의 시변동성에 대해 고려할 필요가 있음을 시사한다.

• 한국환경과학회지
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• 제15권10호
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• pp.951-960
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• 2006

The eco-hydrodynamic model was used to estimate the environmental capacity in Gamak Bay. It is composed of the three-dimensional hydrodynamic model for the simulation of water flow and ecosystem model for the simulation of phytoplankton. As the results of three-dimensional hydrodynamic simulation, the computed tidal currents are toward the inner part of bay through Yeosu Harbor and the southern mouth of the bay during the flood tide, and being in the opposite direction during the ebb tide. The computed residual currents were dominated southward flow at Yeosu Harbor and sea flow at mouth of bay, The comparison between the simulated and observed tidal ellipses at three station showed fairly good agreement. The distributions of COD in the Gamak bay were simulated and reproduced by an ecosystem model. The simulated results of COD were fairly good coincided with the observed values within relative error of 1.93%, correlation coefficient(r) of 0.88. In order to estimate the environmental capacity in Gamak bay, the simulations were performed by controlling quantitatively the pollution loads with an ecosystem model. In case the pollution loads including streams become 10 times as high as the present loads, the results showed the concentration of COD to be $1.33{\sim}4.74mg/{\ell}(mean\;2.28mg/{\ell})$, which is the third class criterion of Korean standards for marine water quality In case the pollution loads including streams become 30 times as high as the present loads, the results showed the concentration of COD to be $1.38{\sim}7.87mg/{\ell}(mean\;2.97mg/{\ell})$, which is the third class criterion of Korean standards for marine water quality. In case the pollution loads including streams become 50 times as high as the present loads, the results showed the concentration of COD to be $1.44{\sim}9.80mg/{\ell}(mean\;3.56mg/{\ell})$, which is the third class criterion of Korean standards for marine water quality.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.177-184
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• 2009

Cavitating flow simulation is of practical importance for many engineering systems, such as marine propellers, pump impellers, nozzles, injectors, torpedoes, etc. The present work has focused on the simulation of cavitating flow past cylinders with strong side flows. The governing equation is the Navier-Stokes equation based on the homogeneous mixture model. The momentum and energy equation is in the mixture phase while the continuity equation is solved liquid and vapor phase, separately. An implicit dual time and preconditioning method are employed for computational analysis. For the code validation, the results from the present solver have been compared with experiments and other numerical results. A fairly good agreement with the experimental data and other numerical results have been obtained. After the code validation, the strong side flow was applied to include the wake flow effects of the submarine or ocean tide.

• 한국환경과학회지
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• 제8권3호
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• pp.355-361
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• 1999

The aim of this study is to develop the water quality simulation model (BAYQUAL) that deal with the physical, chemical and biological aspects of fate/behavior of pollutants in the bay. BAYQUAL is a two dimensional, time-variable finite element water quality model based on the flow simulation model in bay(BAYFLOW). The algorithm is composed of a hydrodynamic module which solves the equations of motion and continuity, a pollutnat dispersion module which solves the dispersion-advection equation. The applicability and feasibility of the model are discussed by applications of the model to the Kwangyang bay of south coastal waters of Korea. Based on the field data, the BAYQUAL model was calibrated and verified. The results were in good agreement with measured value within relative error of 14% for COD, T-N, T-P. Numerical simulations of velocity components and tide amplitude(M2) were agreed closely with the actual data.

• Water Engineering Research
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• 제6권1호
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• pp.1-15
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• 2005

The numerical model, FLUENT, was employed to investigate the effect of the heated water discharged from the diffuser of Boryung Power Plant. Temperature patterns of the thermal effluent discharged from two proposed types of the diffusers was evaluated for maximum flood and maximum ebb tide. The hydraulic model experiments were also performed in the reduced scale of 1/150 to verify the numerical simulation results. The buoyant jets discharged from the diffusers were found to be significantly affected by the ambient flows beyond the region where the effluent momentum was dissipated. Both the numerical and experimental results showed that the area of the excess isotherm for Type 1 diffuser was larger than that for Type 2 diffuser. Type 2 diffuser system was observed to be a more effective diffuser design than Type 1 diffuser system based on the temperature reduction and excess isotherm obtained from the numerical simulation in the ambient flows.

• 한국전산유체공학회지
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• 제14권4호
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• pp.78-85
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• 2009

Cavitating flow simulation is of practical importance for many engineering systems, such as marine propellers, pump impellers, nozzles, injectors, torpedoes, etc. The present work has focused on the simulation of cavitating flow past cylinders with strong side flows. The governing equation is the Navier-Stokes equation based on the homogeneous mixture model. The momentum and energy equation is in the mixture phase while the continuity equation is solved liquid and vapor phase, separately. An implicit dual time and preconditioning method are employed for computational analysis. For the code validation, the results from the present solver have been compared with experiments and other numerical results. A fairly good agreement with the experimental data and other numerical results have been obtained. After the code validation, the strong side flow was applied to include the wake flow effects of the submarine or ocean tide.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1993년도 정기학술강연회 발표논문 초록집
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• pp.14-19
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• 1993

Gymnodinium mikimotoi is one of several species of flagellates that cause harmful red tides. The red tides of G. mikimotoi have occurred only along $33-35^{\circ}$ N, e.g. Chinhae Bay in Korea, tile Seto Inland Sea and Kumane-Nada in Japan. I try to reproduce the formation of red ties of G. mikimotoi at Suo-Nada and Iyo-Nada, the western part of Seto Inland Sea, Japan in July 1985 with the use of four-dimensional assimilation model including the biological process of G. mikimotoi in this paper. (omitted)

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2007년도 한국우주과학회보 제16권1호
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• pp.61-61
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• 2007

• 한국해양환경ㆍ에너지학회지
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• 제13권4호
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• pp.270-278
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• 2010

선행연구에서 우리나라 남해안을 대상으로 상용모형인 MIKE21 모형을 사용하여 실시간 조석 및 조석-해일 결합모형을 수립하였다. 본 연구에서는 이를 토대로 마산해역에서 범람모의에 대한 적용성을 검토하였다. 실제 적용에 앞서 가상적인 인공구조물의 범람에 대한 영향성 분석을 시행하였다. 범람 모의에 인공구조물을 포함시킨 결과 침수속도가 지체되어 침수면적이 감소하고 있는 반면 침수심은 별 차이를 보이지 않고 있다. 한편 실해역에 대한 결합모형과 폭풍해일모형의 범람 적용을 비교한 결과, 침수면적과 침수심은 유사한 결과를 보이고 있는 반면 최대 범람에 이르는 시간은 결합모형이 보다 타당한 결과를 나타내고 있다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2006년도 추계학술발표회
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• pp.217-219
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• 2006

This study focused an water quality response to land-based pollution loads and the appropriate pollutant load reduction in Chinhae Bay using an eco-hydrodynamic model. Land-based discharge foam urban areas, industrial complex and sewage treatment plant was the greatest contributor to cause red-tide blooms and summer hypoxia. Tidal currents velocity af the ebb tide was about 10 cm/s stronger than that of the flood tide. A residual current was simulated to. have a slightly complicated pattern with ranging from 0.1 to. 2.7 cm/s. In Masan Bay, pollutant materials cannot flaw from the inner to the outer bay easily because af residual currents flaw southward at surface and northward at the bottom. The simulation results of COD distribution showedhigh concentrations aver 3 mg/L in the inner part of Masan Bay related pollutant discharge, and charge, and lower levels less than 1.5mg/L in the central part of Chinhae Bay. For improvement water quality in Chinhae Bay, it is necessary to reduce the organic and inorganic loads from paint sources by mare than 50% and ameliorate severe polluted sediment.