• 한국항해항만학회지
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• 제34권6호
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• pp.417-422
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• 2010

정수중 부선 주위의 유동 특성을 조사 및 분석하기 위하여 부선의 저항성능을 모형시험과 CFD를 이용한 수치계산에 의하여 해석하였다. 모형실험은 무한수심 조건에서의 회류수조에서 저항과 선측파형 등을 관측하였으며, 유동장 해석을 위하여 VOF(Volume of Fluid)법을 기초로 한 수치 시뮬레이션을 이행하였다. 부선의 형태에 따르는 유동특성을 파악하기 위하여 서로 다른 모습의 부선 모형을 제작하였으며, 모형실험은 설계속도를 7kts로 정하고 역조와 순조의 조류 영향을 고려하여 5kts~10kts의 구간에서 실험을 실시하여 각 속도에 따르는 저항 특성을 비교 검토 하였다. 수치 시뮬레이션은 일정 속도에서 만재상태를 기준으로 하여 계산을 수행하였으며 수조 실험 결과와 상호 비교함으로서 본 수치계산법의 타당성을 검증할 수 있었으며, 부선의 저항성능 및 선체 주위 유동장의 특성을 분석하였다. 저속일 때 25% 정도의 저항의 차이가 발생하고, 7kts부터 유효마력이 급격히 증가하는 현상을 파악할 수 있었다.

• 대기
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• 제18권4호
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• pp.507-524
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• 2008

In this paper, future climate changes over East Asia($20^{\circ}{\sim}50^{\circ}N$, $100^{\circ}{\sim}150^{\circ}E$) are projected by anthropogenic forcing of greenhouse gases and aerosols using coupled atmosphere-ocean general circulation model (AOGCM) simulations based on Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) B1, A1B and A2 scenarios. Before projection future climate, model performance is assessed by the $20^{th}$ Century (20C3M) experiment with bias, root Mean Square Error (RMSE), ratio of standard deviation, Taylor diagram analysis. The result of examination of the seasonal uncertainty of T2m and PCP shows that cold bias, lowered than that of observation, of T2m and wet bias, larger than that of observation, of PCP are found over East Asia. The largest wet bias is found in winter and the largest cold bias is found in summer. The RMSE of temperature in the annual mean increases and this trend happens in winter, too. That is, higher resolution model shows generally better performances in simulation T2m and PCP. Based on IPCC SRES scenarios, East Asia will experience warmer and wetter climate in the coming $21^{st}$ century. It is predict the T2m increase in East Asia is larger than global mean temperature. As the latitude goes high, the warming over the continents of East Asia showed much more increase than that over the ocean. An enhanced land-sea contrast is proposed as a possible mechanism of the intensified Asian summer monsoon. But, the inter-model variability in PCP changes is large.

• 한국해안·해양공학회논문집
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• 제22권5호
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• pp.333-343
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• 2010

목포해역에서 조위와 조류 관측자료를 분석하여, 낙조류 우세 조류특성을 보이는 것을 확인하였으며 낙조류 우세를 발생하는 물리적 요인에 대해 검토하였다. 노출한계수심, 바닥마찰응력 산정방법, 해안 매립, 조석의 진폭, 비선형 조석, 와점성계수와 목포해역의 낙조류 우세현상의 관련성에 대해서 2차원 해수유동 모형을 적용하여 자세히 조사하였다. 다양한 조건에 대한 모의결과로부터 노출한계수심과 와점성계수는 모의결과에 거의 영향을 주지 않으며, 바닥마찰응력이 증가함에 따라 조류의 비선형성이 증가하여 낙조류 우세현상이 나타나는 것을 확인할 수 있었다. 간사지가 미치는 영향은 간사지가 육지로 바뀌면 낙조류 우세가 심해지고, 간사지가 바다로 바뀌면 낙조류 우세가 사라지는 것을 확인할 수 있었다. 그동안 목포해역에서 진행되어온 해안매립사업은 낙조우세현상을 심화시켜 왔음을 확인할 수 있었으며, 비선형 조석은 비대칭 조류를 생성하는 데 결정적인 역할을 하여 조류의 비대칭성인 강한 목포해역에서 조류를 모의할 때는 개방경계 조위에 비선형조석을 포함해야 함을 확인할 수 있었다.

• Journal of the korean society of oceanography
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• 제37권3호
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• pp.169-177
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• 2002

An eddy-resolving free-surface primitive-equation model with nonlinear terrain-following coordinates is established to study the exchange of water masses among the Asian marginal seas and their adjacent waters. A curvilinear coordinate system is used to generate the horizontal grid with a variable resolution for the regional oceans from $5^{\circ}$S to $45^{\circ}$N and $100^{\circ}$E to $155^{\circ}$E. The higher resolution region has about a 10 km by 10 km grid covering the complex geometry of the coastal marginal seas, while the lower resolution region has about a 30 km by 30 km grid covering the eastern Pacific. The model is initialized by the Levitus annual climitology and forced by the monthly mean air-sea fluxes of momentum, heat, and freshwater derived from the Comprehensive Ocean-Atmosphere Data Set. High-resolution and low-viscosity are identified as the key factors for a better representation of the exchange of waters through narrow straits and passages between the marginal seas and their adjacent waters. The dynamics of the loop currents and eddies in the South China Sea and Celebes Sea are examined in detail. It has found that the anticyclonic loop and detached eddies from the Kuroshio through the Luzon Strait play an important role in transporting warm and salty water into the South China Sea, while the cyclonic circulation of the Mindanao Current in the Celebes Sea plays a role in contributing cold water to the Indonesian throughflow. The deep undercurrent of the western Pacific is shown to provide fresher water to the South China Sea and Celebes Sea. These modeling results suggest that the exchange processes via the narrow straits and passages are of fundamental importance to the maintenance of water masses for the marginal sea region.

• 수산해양기술연구
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• 제30권3호
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• pp.142-149
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• 1994

In order to investigate the environmental properties of set net grounds located in the coastal waters of Yeosu. The current in the vicinity of set net grounds was observed by drogue and current meter in 1990 and 1992. The results obtained are summarized as follows: The direction of tidal current at the north enterance of Yeosu bay was southerly in ebb and northwesterly in flood without the distiction of the neap tide and the spring tide. In spring tide the maximum Velocity of the tidal current was 68 cm/sec in ebb and 66 cm/sec in flood. In neap tide the maximum velocity of the tidal current was 37 cm/sec in ebb and 35 cm/sec in flood. And so the direction of residual current was the south ward mainly and 21 cm/sec. The direction of tidal current at set net fishing grounds was southwesterly in ebb and westerly or northwesterly in flood. Regardless of the distinction of neap and spring. The maximum velocity of the current in spring tide was 50 cm/sec in ebb and 40 cm/sec in flood and that in neap was 28 cm/sec in ebb and 25 cm/sec in flood. In spring tide the speed vector along the major axis of semidiurnal tide component was three times as large as diurnal tide. In neap tide, however, the speed vector was about 50% less then that in spring tide, and the semidiurnal tide and diurnal tide were equal in the size of current ellipse and the direction of major axis. The sea area had a southwesterly residual current. 11 cm/sec in spring tide and 7 cm/sec in neap tide. According to the result of drogue tracking, the vicinity of set net fishing ground had a southerly residual current which formed in Yeosu Bay and a weak westerly residual current toward Dolsando from Namhedo. Therefore, set net fishing ground in coastal water of Yeosu was distributed in boundary of inner water which formed from Seamjin river and offshore water supplied from the vicinity of Sorido and Yochido.

• 한국해안해양공학회지
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• 제19권6호
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• pp.547-556
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• 2007

해운대 연안에서 파랑, 해빈류 및 조석류에 의한 표사이동을 TRANSPOR-2004를 이용해서 계절별 표사수지를 분석하였다. 그 결과로부터 년간의 표사수지를 계산하고 표사의 유출입경로를 유추하였다. 해수욕장의 동쪽 해안을 따라 해수욕장으로 유입된 표사는 중앙부에서 일부는 20% 정도는 외해로 유출하고 80% 정도는 해안을 따라 동백섬 쪽으로 이동하는 패턴을 나타냈다. 또한 동백섬의 남쪽에선 해안을 따라 해수욕장으로 유입되는 표사이동 패턴도 나타났다. 이 결과는 Gao 모델을 이용하여 봄과 가을의 퇴적물 이동 패턴을 계산한 결과와도 잘 일치하는 것으로 나타났다.

• Ocean and Polar Research
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• 제27권4호
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• pp.433-441
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• 2005

To investigate the characteristics of tidal currents and water circulation in the coastal waters off the Taean Peninsula, tidal currents and sea levels were measured at the study area from 1998 to 2004. In the central waterway to the south of Changan Sand Ridge, mean speed of tidal currents and residual currents were 74.0cm/s, 17.8cm/s respectively; the dominant residual currents flowed northeastward, and the amplitudes of semi-diurnal components $(M_2,\;S_2)$ were larger than diurnal components $(O_1,\;K_1)$. The flood and ebb tidal currents were northeastward and southwestward, respectively, and each period was about 6 hours for them, which was consistent with the period of sea levels at the study area. In the coastal region near Hakampo, Taean, mean velocities of tidal currents and residual currents were 46.1cm/s, 30.8cm/s respectively, and the dominant residual currents flowed southwestward. The amplitudes of shallow water constituents $(M_4,\;MS_4)$ were relatively laige, which were weaker to the northeastern coastal region off Mineodo. The northeastward flow continued for about $2{\sim}3$ hours, while the southwestward flow continued for about $9{\sim}10$ hours near Hakampo during the tidal period. Tidal currents flowed northeastward in the central area of the waterway during the period from the Low Water Level (LWL) to the High Water Level (HWL). While the currents in the coastal region flowed northeastward for the first 3 hours after the LWL, southwestward counter-currents flowed between 3 and 6 hours after the LWL. During the period from the HWL to the LWL, the dominant currents flowed southwestward in the study area except to the northeastern coastal region off Mineodo. Along the shorelines, the counter-currents flowed northward between 4 and 6 hours after the HWL. It seems that the counter-currents near the coastal region are caused by the topography and the geography of the shorelines at the study area.

• 한국해안해양공학회지
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• 제4권4호
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• pp.231-242
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• 1992

분 연구에서는 수치모형을 이용하여 조류 및 취송류의 순환형태를 고찰하였다. 사용된 모형은 유체의 운동 및 연속방정식에 기초한 연직평균 2차편 모형으로서 양해법을 사용하며, 개방경계에서의 해수면 변화와 바람의 전단력에 의한 forcing을 포함한다. 모형의 영역은 북위 35$^{\circ}$~36$^{\circ}$40', 동경 125$^{\circ}$~126$^{\circ}$40'이며 경사간격은 x, y 방향 공히 5km이다. 피해측에서 22일간 관측된 조석(2개 지점) 및 조류(1개 지점) 자료와 비교한 결과 본 모형은 4개 주요 분조에 의한 조석 및 조류를 정확도 90% 이내로 재현하였다. 여섯 가지 경우의 가상적인 바람에 대한 해석을 통하여 흐름의 분포양상과 지역적인 특성을 고찰하였다. 그 결과, 풍향에 관계 없이 강한 연안류가 발생하며, 또한 해저지형의 영향으로 부안 외해측에 주반경 40km의 지역적인 과류가 발생함을 확인하였다.

• 한국해안해양공학회지
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• 제14권2호
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• pp.151-160
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• 2002

3차원 흐름 모델링시스템 FEMOS를 개발하고, 아산만 조류분포를 모의하였다. 개발된 시스템은 조간대 모의를 할 수 있으며, 수치해석방법으로 유한요소법을 사용하여 격자형성이 자유스러우며, 복잡한 해안선을 효과적으로 나타낼 수 있다. 넓은 조간대와 큰 조차, 얕은 수심을 가진 아산만의 조류분포 모의에 시스템을 적용한 결과, 모의결과는 장기간의 중층에서 유속변화, 층별 유속의 시간변화와 일치하는 양호한 계산결과를 보였다. 아산항 건설 전·후 조류 계산결과에 기초하여 산정한 바닥마찰응력 분포 변화를 수심변화 관측결과와 비교한 결과, 마찰음력이 증가하는 곳에서는 침식으로 수심이 깊어지고, 감소하는 곳에서는 퇴적으로 수심이 얕아지고 있음을 확인할 수 있었다. 개발된 본 모델링시스템은 그 적용성이 입증됨에 따라 복잡한 해안선과 지형을 가진 연안해역의 해수유동 연구에 널리 활용될 수 있을 것이다.

• 한국환경과학회지
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• 제16권3호
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• pp.261-267
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• 2007

In this study, the Slab Ocean Model (SOM) is coupled with an Atmospheric General Circulation Model (AGCM) which developed in University of Kangnung based on the land surface model of Biosphere-Atmosphere Transfer Scheme (BATS). The purposes of this study are to understand radiative role of clouds considering of the atmospheric feedback, and to compare the Clouds Radiative Forcing (CRF) come from the analyses using the clear-cloud sky method and CGCM. The new CGCM was integrated by using two sets of the clouds with radiative role (EXP-A) and without radiative role (EXP-B). Clouds in this two cases show the negative effect $-26.0\;Wm^{-2}$ of difference of radiation budget at top of atmosphere (TOA). The annual global means radiation budget of this simulation at TOA is larger than the estimations ($-17.0 Wm^{-2}$) came from Earth Radiation Budget Experiment (ERBE). The work showed the surface negative effect with $-18.6 Wm^{-2}$ in the two different simulations of CRF. Otherwise, sensible heat flux in the simulation shows a great contribution with positive forcing of $+24.4 Wm^{-2}$. It is found that cooling effect to the surface temperature due to radiative role of clouds is about $7.5^{\circ}C$. From this study it could make an accurate of the different CRF estimation considering either feedback of EXP-B or not EXP-A under clear-sky and cloud-sky conditions respectively at TOA. This result clearly shows its difference of CRF $-11.1 Wm^{-2}$.