• Water for future
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• v.18 no.1
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• pp.67-73
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• 1985

Tidal propagation in the Keum River has been routinely handled by numerical integration of the long fravity wave equation by Dronkers. The dynamic equations include non-linear terms thereby reproducing the shallow water tides. The model was used to compute tidal distribution of the Kum River for aveage spring, mean, neap tidal conditions and further utilised to investigate the waterlevel response within tidal reaches by combined tide and flood discharge effects. The objective of this initial study is to investigate the tidal dynamics of the lower reaches of the Keum River under the condition of before-cross-channel barrage construction.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.4
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• pp.248-257
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• 2010

Applicability of the MIKE21 model as a real time coupled tide-surge model is examined prior to the application as an inundation model. Though the model domain contains the whole southern coasts of Korean Peninsula, the results of tide simulations show good agreement with the observed values. Moreover, the coupled tide-surge model simulates water levels well, especially near the sites which typhoon MAEMI(0314) struck, such as at Tongyung, Masan and Pusan. In addition, it is confirmed that the interaction between storm surge and tide is notable where the water depth is small and the tidal range is large, which indicates the necessity of coupled model especially at the southwestern coast.

• Water for future
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• v.21 no.1
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• pp.87-94
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• 1988

Tidal asymmetry in the Keum River Estuary has been investigated from the observed tides. Despite strong frictional attenuation within the estuary, the $M_4$ tides reach significant amplitude, resulting in strong tidal distortion. The observed asymmetry over the area shows that generally more intense flood flows transport more sediment that do less intense ebb flows of longer duration. This causes filling of the estaury as evidenced by sand flats spreaded over the inner area. The spatial distribution of peak bottom stress associated with the dominant $M_2$ and $M_4$ tides calculated via two-dimensional numerical tidal model suggest that present tidal sedimentation regimemay be altered, sepecially in the approach channel to outer Kunsan Port and downstream part of the dike, due to the construction of barrier.

• Water for future
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• v.21 no.2
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• pp.183-192
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• 1988

The previous two-dimensional non-linear tidal model of the East China Sea(Choi, 1980) has been further refined to resolve the flow over the ocntinental shelf in more detail. The mesh resolution of the present finite-difference grid system used is 4 minutes latitude by 5 minutes longitude over the entire shelf. The developed fine grid two-dimensional model was utilized to reproduce the $M_2$ tide and $M_4$ tide for the East China Sea contnental shelf. There is general agreement between the model results and the current observation made in the Eastern Yellow Sea, which supports the calculated tidal regime over the shelf. Some preliminary results on maximum bottom stress and tidally-induced residual current were also examined and discussed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.2
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• pp.129-135
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• 1990

A two-dimensional nonlinear tidal model of the Asan Bay has been formulated to examine the tide and related hydraulic phenomena. The $M_2$ tidal regime was first computed using the model and the model also was to derive the maximum bed stress and transport potential in the region. Preliminary assessment of relation between sediment transport and the maximum bed stress distribution determined from the model are described.

• Journal of the Korean earth science society
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• v.37 no.7
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• pp.465-475
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• 2016

The diurnal and semidiurnal tides in the global atmosphere are examined using 3-hourly geopotential height field of the state-of-the-art reanalysis data. Unlike the previous studies, the spatial structure and seasonality of those tides are analyzed from the surface of the earth to the stratosphere. It is found that, at most levels, diurnal tide is strong in the midlatitudes while semidiurnal tide is predominant in the tropics. The former shows strong seasonal cycle with a larger amplitude in summer than in winter in both hemispheres. This is different from the semidiurnal tide which has essentially no seasonal cycle. In term of the vertical structure, while semidiurnal tide has a barotropic structure, diurnal tide exhibits a distinct vertical structure with increased amplitude and height. Especially tropical diurnal tide exhibits a nearly opposite phase from the surface to the free troposphere, and to the upper stratosphere. Its amplitude also varies nonlinearly with height, possibly influenced by water vapor, ozone, gravity waves and solar radiation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.4
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• pp.338-349
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• 1993

Most of numerical models for studying tide-induced residual currents (TIRC) were to dimensional depth averaged models which were confined to anlayze the horizontal structure of TIRC. In this study, TIRC occurring around a circular island was simulated with the three-dimensional spectral model which employed by the finite difference method in the horizontal direction and the expansion of basis function in the vertical direction. The main results of numerical experiment can be summarized as follows. Firstly. both topographic and nonlinear effect played an important role in the generation of TIRC. Secondly, when the currents were rotary clockwise. the horizontal structure of TIRC appeared to rotate in the same direction. These results were consistent with those of previous studies of two-dimensional numerical models.

• Water for future
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• v.24 no.2
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• pp.81-95
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• 1991

For investigation of the interaction of tide and river flow, the derived equations are solved analytically using the approximation method of perturbation. The convective inertia and nonlinear bottom friction terms are included in the derivations. The harmonic analysis is applied to decompose the complicated interaction of the freshwater discharge with various constituents of tide into its individual interaction with each constituent. In this study, four main constituents(M2, S2, Kl, 01) are included. The relations of dimensionless parameters of the tide, especially the dimensionless damping modulus, are then determined for each solution. The results show that analytical solution of dimensionless damping modulus underestimates the measured value obtained from harmonic analysis. Results of water level obtained by applying the analytical model to a tidal reach of the Keum River in the years 1981 and 1982 show very good agreement with those obtained from the harmonic analysis.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.269-269
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• 2022

최근 낙동강 하구 기수생태 복원에 있어서 중요한 요소 중 하나는 하굿둑 외해측의 보다 높은 정도를 가지는 조석예보치 산정과 이를 통해 하굿둑 방류량과 해수 유입량을 추정하여 주변 환경 등을 예측할 수 있다. 기수생태 복원이 본격으로 논의가 진행 전인 2016년까지는 하구에서 수km 떨어진 기존 조위관측소(부산 및 가덕도)를 활용하여 하류수위를 예측하여 왔지만 조위 높이와 위상 차이로 인하여 활용이 용이하지 않다. 따라서, 낙동강 하굿둑 인접 외해역에서 조석 영향을 받는 수위관측치를 이용하여 조석조화분해를 통해 조위 예측을 보다 정밀하게 산정하는 것이 필요하다. 연구방법으로는 낙동강 하굿둑 외해역에서 관측된 2016년, 2017년 각각 1년간 10분간격으로 관측자료의 저장상태 및 이상자료 유무를 확인하고, 조석조화분해 프로그램인 TASK2000(Tidal Analysis Software Kit) Package를 이용하여 2016년, 2017년 낙동강 하굿둑 인접 외해역에서 관측된 조위자료를 각각 조석조화분해한 결과로 관측조위와 예측조위 비교하였고, 관측조위와 예측조위를 뺀 성분인 조석잔차성분을 구했다. 조화분해결과, 낙동강 하굿둑 외해역은 일반적인 연안역의 조석과는 달리 하천수의 유출, 배수갑문의 조작, 연안사주지형에 의한 조석변형 등 매우 복잡하고 불규칙적인 특성인 기상성분(기압, 바람 등)에 의한 교란을 고려한다면 예측정확도가 상당부분 확보되는 것으로 나타났다. 또한 장주기 성분과 비선형 조석성분의 크기를 비교해 볼 때 거의 편차가 없이 나타나 조석조화상수를 이용한 예보 가능성을 확인할 수 있었다. 조위검증은 2016년의 1년치의 조석자료를 이용하여 조화분해된 조화상수 63개를 이용하여 2017년의 조석 예보치를 산정하였으며, 이를 2017년의 낙동강 하굿둑 외해역의 조석관측치와 조석예측치를 1대 1 비교하는 방식으로 검증하였고, 이들의 상관관계를 파악하기 위하여 두 성분에 대하여 Regression Analysis를 수행하여 예측조위와 관측조위 사이에는 Pre=0.9535×Obs+0.396과 같은 관계식이 성립하는 것으로 분석되었다. 또한, 두 성분간의 상관도는 0.9535로 높게 나타났다. 조위예측 프로그램인 TASK2000 Package 중 MARIE를 이용한 조위예측 프로그램의 신뢰도가 매우 높은 것으로 판단되고, 해당년도 조위예측 시에는 가능하면 직전년도의 1년 조석관측자료를 조화분해하고 얻어진 조화상수를 이용하여 조위예측을 실시하면 보다 정확한 자료를 얻을 수 있다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.2
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• pp.137-145
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• 1996

Effects of nonlinear terms on the generation of M$_2$ tide residual elevation and M$_4$ tide in the Yellow Sea and the East China Sea are investigated using a depth-integrated two-dimensional nonlinear M$_2$tidal model. The model domain (117$^{\circ}$E-130$^{\circ}$E, 24$^{\circ}$N-41$^{\circ}$N) covers the whole region of the Yellow Sea and the East China Sea with grid resolution of 1/6$^{\circ}$ in longitude and 1/8$^{\circ}$in latitude. A radiational boundary condition is used along the open boundaries. Calculations show that advection terms yield negative residual elevation, while shallow-water terms in continuity equation yield positive residual elevation. The contribution of both advection terms and shallow-water terms to tile generation of the M$_4$ constituent is more than 90 percents, but that of quadratic bottom friction terms to the M$_4$ constituent is comparatively small.