• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1994.07a
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• pp.14-18
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• 1994

Barotropic Model을 이용하여 바람의 계절변화에 따른 대마난류의 형성을 살펴보았다. 모델 격자간격은 위도와 경도방향 모두 $0.25^{\circ}$로 하였고 바람은 Hellerman & Rosenstein (1983)의 바람을 이용하였다. 모델결과에 의하면 대마난류는 대만해협이 음의 유선함수 (Stream Function) 값을 갖는 동계 (10월-3월)에는 쿠로시오로 부터 직접 분기되어 형성되며 대만해협이 양의 유선함수값을 갖는 하계 (4월-9월)에는 대만해협을 통해 유입된 대만난류가 대마난류의 기원으로 나타난다. 이러한 대만난류 유입경로의 계절변화는 쿠로시오 수송량의 계절변화에 의한 것이 아니라 연해 (동지나해) 에서의 바람의 계절변화에 의해 야기되는 것으로 사료된다. 대한해협과 대만해협에서의 수송량과 쿠로시오의 수송량변화는 각각의 최대, 최소값만을 고려하면 쿠로시오와 대한해협에서의 수송량 변화는 약 $180^{\circ}$의 위상차를 갖으며, 대만해협에서의 수송량변화는 북풍계열의 바람이 우세한 동계를 제외하고는 쿠로시오의 수송량변화와 같은 위상을 갖는다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.1
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• pp.58-64
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• 1992

A barotropic model is run over the Northwest Pacific Ocean to examine the formation and transport of the Tsushima Warm Current. The results indicate that the Tsushima Warm Current is a downstream extension of the Taiwan Warm Current. Local wind does not change the amount of transport of Tsushima Warm Current but it changes much the initial flow pattern of Tsushima Warm Current such that for southerly wind, the transport is through the Taiwan Strait but for northerly wind, it is through the eastern side of Taiwan.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.160-161
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• 2000

동지나해로부터 동해로 유입되는 대마난류의 계절변동과 수송량에 관한 많은 연구가 대한해협에서 수행되어왔다. 이러한 연구들은 수문학적 자료로부터 Margule's equation으로 대한해협을 통과하는 수송량을 계산하거나 부산, 이즈하라와 하카타의 해수면 변동자료로 각 지점간의 해면차와 대한해협에서 실제 관측한 유속 또는 평균 지형류와의 관계를 연구했다. 또한 대한해협의 몇개의 지점에 대하여 ADCP와 CTD 관측을 통해서 대마난류의 실제유속과 지형류적 유속을 비교였다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.176-178
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• 2000

대기경계층내에서의 흐름은 평균류, 난류(Turbulence) 그리고 파동(wave) 3가지로 분류되는데 수평적으로 수 ms$^{-1}$ 연직적으로 수 cms$^{-1}$의 평균류에 의해서 수중기, 운동량, 열, 오염물질의 수송이 일어나며 이것들은 난류에 의해서 연직적 수송이 일어 난다. 그리고 평균류의 시어(shear)나 평균류가 장애물을 만나면서 형성되는 파동에 의해서 운동량, 에너지 등의 수송이 이루어진다(Stull., 1988). (중략)

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.134-134
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• 2011

3차원 난류 부력젵의 혼합을 큰 와 모의(large-eddy simulation) 기법을 이용하여 수치모의 한다. 개발된 수치모형은 3차원 열동수역학 모형을 이용하여 부력젵의 퍼짐, 자기 보존 그리고 주변류의 연행 등을 포함하는 난류젵의 동적 특성을 분석할 수 있다. 수치해석에서 하부격자규모 (subgrid scale, SGS) 난류 응력은 부력항을 수정한 Smagorinsky 모형을 이용한다. 여과된 엔탈피 수송방정식에서 하부격자규모의 스칼라 플럭스는 상수의 SGS Prandtl 수를 가지는 단순 경사수송 가설에 근거하여 모의한다. 계산된 결과를 실험결과와 비교하며, 결과는 양호하게 일치함을 보여준다. 계산결과에 따르면 부력항의 수정이나 SGS 난류 Prandtl 수는 결과에 큰 영향을 미치지 않지만 SGS 모형 상수인 Cs 값은 부력젵 확산 예측에 중요한 영향을 미치는 것으로 나타났다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.6 no.4
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• pp.364-374
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• 1994

The separation mechanism of the Tsushima Warm Current and the effects of seasonal wind stress on the separation position are studied by use of a barotropic numerical model. The grid spacing of 0.25$^{\circ}$ both in latitude and longitude is used in the model, and Hellerman and Rosenstein's wind (1983) is applied to the sea surface as seasonal wind stress. According to the model results, during winter seasons (from October to March) when northly wind is prevailing, the Tsushima Warm Current is formed by direct separation from the Kuroshio on the continental slope southwest of Kyushu. On the other hand, during summer seasons (from April to September), the Taiwan Current that flows through the Taiwan Strait seems to be the origin of the Tsushima Warm Current. The Kuroshio reaches its maximum transport during winter seasons, and the minimum during summer. The transport of the Taiwan Current shows a phase lag of about 160$^{\circ}$ relative to the Kuroshio. The transport variation of the Tsushima Warm Current agrees with that of the Kuroshio when the former is shifted by 120$^{\circ}$(about 4 months).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.3
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• pp.439-447
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• 2019

Some dynamical issues about the Tsushima Warm Current (TWC) are reviewed and checked for the remaining unresolved problems, focusing on the formation of the TWC, seasonal variation of its volume transport and its branching in the East Sea. The TWC is a part of the North Pacific (NP) subtropical gyre driven by the NP global wind system. However, the quantitative amount of volume transport is sensitive to friction, basin geometry, barrier effect and so on. Among many causes suggested by many scientists, subpolar winds are found to be most closely related with the seasonal variation of TWC volume transport. However, more studies relating the latter not only to the subpolar winds but also to those including the subtropical winds seem to be required. The branching of the TWC has been known to be due to the western intensification for the East Korean Warm Current (EKWC) and to the bottom trapping for the Nearshore Branch. Since the former hypothesis is problematic in explaining the seasonal variation of the EKWC, other candidate mechanisms may need to be considered.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.6 s.237
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• pp.687-695
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• 2005

On the notion that the Reynolds stresses are transported with different time scale depending on the transport direction, the third order velocity correlations are represented by a new turbulent gradient transport model with tonsorial Lagrangian time scale. In order to verify the proposed model, DNS data are first obtained in a turbulent channel flow at Re = 180 and tonsorial Lagrangian time scales are computed. The present model predictions are compared with DNS data and those predicted by the third-order turbulent transport model of Hanjalic and Launder that uses a scalar time scale. The result demonstrates that the Reynolds stresses are indeed transported with different time scale depending on the transport direction.

• Journal of Marine Life Science
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• v.4 no.1
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• pp.14-21
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• 2019

This review paper discussed the decadal fluctuations in the catch of the common squid, Todarodes pacificus (T. pacificus) by focusing on migration and distribution patterns. Since 1980s, changes in T. pacificus catches were due to climate regime shift in Korean waters. Fluctuation patterns of catches were different between the East Sea and the Yellow Sea. Generally PDO (Pacific Decadal Oscillation) phase shows a negative correlation with strength of warm current to the East Sea. In 1980s when PDO was positive phase (+), T. pacificus catch was higher in the Yellow, but it was lower in the East Sea. In 1990s when PDO was negative phase (-), T. pacificus catch showed opposite trend compared with 1980s. Such spatial and decadal fluctuations of T. pacificus catch were due to its northward migration along with the warm current or southward movement against the current. In the East Sea, strong (weak) warm current period, the current path has been shifted toward the East Sea coast of Korea (central East Sea or the coast of Japan). It has a correlation with PDO. In the positive PDO phase (1980s), the fishing ground was located on the eastern side of Ulleungdo, whereas during negative PDO phase (1990s), they were situated near the southeastern coast of the Korean peninsula. In the 1980s, volume transport passing into the Yellow Sea increased, whereas volume transport in the East Sea decreased. This is one of major reason increasing T. pacificus larvae in the Yellow Sea.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.3
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• pp.256-267
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• 1996

In estuarine 3-dimensional numerical modeling. it is very important to calculate vertical eddy viscosity accurately. Various turbulence models employing eddy viscosity concept were applied to the steady flow in an open-channel and the tidal flow in long tidal channel and compared. The evaluations include the verification tests against experimental data sets for steady and tidal flows. The simulation results have shown that the compared models are in good agreements with experimental data of steady flow while only $textsc{k}$-$\varepsilon$ model, $textsc{k}$-ι model, and 1-equation model with well-defined mixing length profile give good agreements with experimental data of tidal flow.