• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2009.04a
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• pp.49-53
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• 2009

In this study, point gravity was measured to achieve terrestrid gravity data and the gravity is important element in precise geoid modelling. Surveys the relative gravity of 56 stations on 1st level route. In addition, it calculates gravity values, analysis gravity survey results using tidal correction, drift correction, datum-free adjustment. These point gravity data could be contribute in development of precise geoid model.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.2
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• pp.79-87
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• 1994

A real-time flood forecasting system(FLOFS) was developed for the real-time and predictive determination of flood discharges and stages, and to aid in flood management decisions in the Keum River Estuary Dam. The system consists of three subsystems : data subsystem, model subsystem, and user subsystem. The data subsystem controls and manages data transmitted from telemetering systems and simulated by models. The model subsystem combines various techniques for rainfall-runoff modeling, tidal-level forecasting modeling, one-dimensional unsteady flood routing, Kalman filtering, and autoregressivemovingaverage(ARMA) modeling. The user subsystem in a menu-driven and man-machine interface system.

• Journal of Ocean Engineering and Technology
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• v.13 no.2 s.32
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• pp.18-25
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• 1999

Western coastal ports of Korea experience severe tidal range with up to 9.7 meter between high and low tides. The significant water level variation implicates many operational difficulties during loading and un-loading from cargo ships. To overcome problems due to tide and to secure the continuous loading operation, a new loading system for container cargo called "container pallet system" is developed and introduced in the paper. Three types of structure forms, offshore structural deck, double bottom structural form and the mixed form, are inverstigated with MSC/NASTRAN software. The results prove that the mixed type structure with truss enforcement is found to be the most appropriate for the region.

• Water for future
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• v.24 no.3
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• pp.83-94
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• 1991

In this paper a discrete extended Kalman filter for the tidal prediction has been developed. The filter is based on a set of difference equations derived from the one dimensional shallow water equations using the finite difference scheme proposed by Lax-Wendroff. The filter gives estimates of the water level and water velocity, together with the parameters in the model which essentially have a random character, e.g. bottom friction and wind stress. The estimates are propagated and updated by the filter when the physical circumstances change. The Kalman-filter is applied to field data gathered in the coastal area alon the West Sea and it is shown that the filter gives satisfactory results in forecasting the waterlevels during storm surge periods.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.526-526
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• 2023

Water circulation plays a crucial role in regulating the salinity of estuaries, which is essential for the survival of estuarine organisms. Changes in freshwater inflows or sea level can have significant impacts on the distribution and abundance of species within these ecosystems. To better understand these dynamics, this paper presents a study of water circulation and salinity distribution in Seomjin River estuary using the Finite Volume Coastal Ocean Model (FVCOM) numerical model. An extreme scenario was simulated to assess the potential impact of tidal currents and river flow discharge on circulation and salinity distribution. The results of this study have important implications for managing estuarine ecosystems and conserving their associated biodiversity.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.357-357
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• 2021

홍수로 인한 침수피해 발생을 최소화하기 위해 정확한 하천의 수위 예측과 리드타임 확보가 매우 중요하다. 특히 조석현상의 영향을 받는 감조하천의 경우 기존의 물리적 수문모형의 적용이 제한되어 하천수위 예측의 정확도가 떨어지기도 한다. 따라서 본 연구에서는 이러한 감조하천 수위 예측의 정확도를 높이기 위해 조석현상을 분리하고 인공신경망을 활용하는 하이브리드 모델을 제안 하였으며 다중 선형회귀분석과 비교 분석하였다. 감조하천에 위치한 교량의 수위데이터에서 Stationary Wavelet Transform으로 조석현상을 분리하였으며, 이외의 수위에 영향을 주는 time series data와 인공신경망(ANN)을 활용하여 1시간, 2시간, 3시간 후의 수위를 예측하였다. 하이브리드 모델은 96% 이상의 정확도를 보였으며 다중 선형회귀 분석과 비교하여도 높은 정확성을 보여주었다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.23 no.4
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• pp.153-178
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• 2018

Most operational uses of wind speed data require measurements at, or estimates generated for, the reference height of 10 m above mean sea level (AMSL). On the Ieodo Ocean Research Station (IORS), wind speed is measured by instruments installed on the lighthouse tower of the roof deck at 42.3 m AMSL. This preliminary study indicates how these data can best be converted into synthetic 10 m wind speed data for operational uses via the Korea Hydrographic and Oceanographic Agency (KHOA) website. We tested three well-known conventional empirical neutral wind profile formulas (a power law (PL); a drag coefficient based logarithmic law (DCLL); and a roughness height based logarithmic law (RHLL)), and compared their results to those generated using a well-known, highly tested and validated logarithmic model (LMS) with a stability function (${\psi}_{\nu}$), to assess the potential use of each method for accurately synthesizing reference level wind speeds. From these experiments, we conclude that the reliable LMS technique and the RHLL technique are both useful for generating reference wind speed data from IORS observations, since these methods produced very similar results: comparisons between the RHLL and the LMS results showed relatively small bias values ($-0.001m\;s^{-1}$) and Root Mean Square Deviations (RMSD, $0.122m\;s^{-1}$). We also compared the synthetic wind speed data generated using each of the four neutral wind profile formulas under examination with Advanced SCATterometer (ASCAT) data. Comparisons revealed that the 'LMS without ${\psi}_{\nu}^{\prime}$ produced the best results, with only $0.191m\;s^{-1}$ of bias and $1.111m\;s^{-1}$ of RMSD. As well as comparing these four different approaches, we also explored potential refinements that could be applied within or through each approach. Firstly, we tested the effect of tidal variations in sea level height on wind speed calculations, through comparison of results generated with and without the adjustment of sea level heights for tidal effects. Tidal adjustment of the sea levels used in reference wind speed calculations resulted in remarkably small bias (<$0.0001m\;s^{-1}$) and RMSD (<$0.012m\;s^{-1}$) values when compared to calculations performed without adjustment, indicating that this tidal effect can be ignored for the purposes of IORS reference wind speed estimates. We also estimated surface roughness heights ($z_0$) based on RHLL and LMS calculations in order to explore the best parameterization of this factor, with results leading to our recommendation of a new $z_0$ parameterization derived from observed wind speed data. Lastly, we suggest the necessity of including a suitable, experimentally derived, surface drag coefficient and $z_0$ formulas within conventional wind profile formulas for situations characterized by strong wind (${\geq}33m\;s^{-1}$) conditions, since without this inclusion the wind adjustment approaches used in this study are only optimal for wind speeds ${\leq}25m\;s^{-1}$.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.11 no.1
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• pp.34-40
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• 1999

Models of beach response due to sea level rise were verified by experiments and potential shoreline retreat around Korea and Japan was predicted. Wave tank experiments demonstrated that not only static retreat by water level rise but also additional retreat by wave action plays an important role in total retreat and additional retreat becomes important on the condition of high waves. The result of long-term analysis of tidal data over past 3 decades shows the tendency toward rise by an average of 1.79 mm/year, which is the result of rise in 29 regions and fall in 12 regions. Based on analyzed rate of long-term sea-level rise, potential shoreline retreats of study area after 50 years were calculated and the result shows serious loss of beach.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.1
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• pp.85-93
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• 2020

The basic information of mean sea level data of all tidal monitoring stations in Korea was reviewed, and the correlation coefficients between the stations were analyzed. Mean sea level changes expected due to global climate change effects were found to show a high correlation of more than 0.75 regardless of the distance between the stations were analyzed. The data between certain stations were found to have negative correlation and low correlation of 0.25 or less, but this was determined by the influence of small data numbers and outliers. However, since these correlations assume a linear increase and a linear relationship, the estimation results may be distorted for data with fluctuating trends that deviate from this assumption. Based on the results of the changing patterns of the MSL data, it shows that a number of the MSL data do not follow the linear trend.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.3
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• pp.111-121
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• 2013

Accurate prediction of sea water temperature has been emphasized to make precise local weather forecast and to understand change of ecosystem. The Yellow Sea, which has turbid water and strong tidal current, is an unique shallow marginal sea. It is essential to include the effects of the turbidity and the strong tidal mixing for the realistic simulation of temperature distribution in the Yellow Sea. Evaluation of ocean circulation model response to vertical mixing scheme and turbidity is primary objective of this study. Three-dimensional ocean circulation model(Regional Ocean Modeling System) was used to perform numerical simulations. Mellor- Yamada level 2.5 closure (M-Y) and K-Profile Parameterization (KPP) scheme were selected for vertical mixing parameterization in this study. Effect of Jerlov water type 1, 3 and 5 was also evaluated. The simulated temperature distribution was compared with the observed data by National Fisheries Research and Development Institute to estimate model's response to turbidity and vertical mixing schemes in the Yellow Sea. Simulations with M-Y vertical mixing scheme produced relatively stronger vertical mixing and warmer bottom temperature than the observation. KPP scheme produced weaker vertical mixing and did not well reproduce tidal mixing front along the coast. However, KPP scheme keeps bottom temperature closer to the observation. Consequently, numerical ocean circulation simulations with M-Y vertical mixing scheme tends to produce well mixed vertical temperature structure and that with KPP vertical mixing scheme tends to make stratified vertical temperature structure. When Jerlov water type is higher, sea surface temperature is high and sea bottom temperature is low because downward shortwave radiation is almost absorbed near the sea surface.