• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.3 no.2
• /
• pp.100-107
• /
• 1991

The purposes of this study are 1) to observe the wave-induced liquefaction in the oceanic seabed. 2) to verify the liquefaction theory proposed by the Authors. The study consists of the field observation and theoretical analysis on the wave-induced liquefaction. In the field observation. The sea bottom pressures. the fluctuating pore pressures and stresses in the seabed and the changes of the water depth were observed for two years. The liquefaction theory proposed by the Authors is verified by the comparing the calculated fluctuating pore pressures with those observed in the field.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.1 no.2 s.2
• /
• pp.75-83
• /
• 2001

In this study, the maintenance problems were investigated through checking the creeks which were improved by close-to-nature river improvement technique. The characteristics of flow were measured at Changsa Creek in Suwon city. The computational results of numerical model with kinematic wave theory was evaluated through observation data about precipitation, velocity, and flow depth. Furthermore, SCS, Clark, and RRL models were compared to the actual observations. As a result, the kinematic wave theory's calculated peak time of discharge concentration occurred little earlier than the actual observation, but the tendency of hydrograph coincided with observation.

• Proceedings of the Acoustical Society of Korea Conference
• /
• 1998.06e
• /
• pp.147-150
• /
• 1998

천해에서의 음파전달은 심해와 비교하여 복잡하고 경계면의 영향을 많이 받으며 서해에서 하계의 평균 수온자료로 잔향음을 계산한 결과 해저면 잔향음(reverberation)이 가장 우세한 것으로 나타났다. 특히 서해에서는 하계에 내부파에 의한 강한 수온약층의 생성이 관측되었으며, 이런 현상은 음파전달에 많은 영향을 줄 것으로 예측된다. 내부파를 조석에 의한 장주기와 단주기로 구분하여 적용한 결과 고주파 음원을 사용할 경우 장주기 내부파에 의한 수온약층의 수식변동에 따른 잔향음은 최대 13dB까지 차이가 났으며 단주기 내부파의 경우 수온약층의 하강한 경우 수온약층이 상승한 경우보다 근거리에서 전달손실 변화가 작았다.

• Proceedings of the Korean Society of Fisheries Technology Conference
• /
• 1995.06a
• /
• pp.369-370
• /
• 1995

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.33 no.4
• /
• pp.139-147
• /
• 2021

In this study, waves were defined using the water surface elevation data observed from the HeMOSU-1 and 2 marine meteorological observation towers installed on the west coast of Korea, and correlation analysis was performed between wave parameters. The wave height and wave period were determined using the wave-train analysis method and the wave spectrum analysis method, and the relationship between the wave parameters was calculated and compared with the previous study. In the relation between representative wave heights, most of the correlation coefficients between waves showed a difference of less than 0.1% in error rate compared to the previous study, and the maximum wave height showed a difference of up to 29%. In addition, as a result of the correlation analysis between the wave periods, the peak period was estimated to be abnormally large at rates of 2.5% and 1.3% in HeMOSU-1&2, respectively, due to the effect of the bimodal spectrum that occurs when the spectral energy density is small.

• Proceedings of the KSRS Conference
• /
• 2007.03a
• /
• pp.198-203
• /
• 2007

최근 인공위성 SAR를 이용한 기술은 해풍，파랑，해류 등과 같은 해양에서 발생되는 다양한 현상을 관측하고 연구하는데 펼수적인 기술로 대두되고 있다. CMOD4, CMOD-IFR2 모델은 해상풍의 크기를 구할 수 있으며，wave-SAR 변환 기법과 inter-look cross-spectra 기법은 파랑의 크기，방향과 같은 물리적 값을 추출할 수 있다. 또한 Doppler shift 기법을 적용하여 해류속도를 구할 수 있다. 본 연구에서는 위의 기법들을 종합적으로 적용하여 SOP (SAR Ocean Processor) 프로세서를 개발하였다. 이 프로세서를 한반도 연안 지역에 적용하여 RADARSAT-1 영상자료로부터 해풍，파랑，해류의 물리적 정보를 추출하였으며，이를 현장 관련 자료와 비교하여 신뢰할만한 결과를 얻을 수 있었다.

• Journal of The Geomorphological Association of Korea
• /
• v.21 no.4
• /
• pp.41-52
• /
• 2014

Coastal dune, as one part of beach system, contributes for beach recovery as well as preventing beach erosion by exchanging sands between beach and dune. Due to high tidal range, the boundary of sand dunes on the west coast of Korean Peninsula is outside the high water line during spring tide and erosion also occurs in high waves during spring high tide. This paper investigates the erosion status of the dunes located in the JangHang beach by analyzing images from camera monitoring system, and tide and wave data observed adjacent to the study site during the passage of 4 typhoons in 2012. It also studies the benefits of camera monitoring images in investigating the dune erosion and analyzing coastal topographic changes.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.8 no.1
• /
• pp.46-52
• /
• 2005

A marine environmental information system (MEIS) useful for optimal route planning of ships running in the ocean was developed. Utilizing the simulated marine environmental data produced by the European Center for Medium-Range Weather Forecasts based on global environmental data observed by satellites, the real-time forecast and long-term statistics of marine environments around planned and probable ship routes are provided. The MEIS consists of a land-based data acquisition and analysis system(MEIS-Center) and a onboard information display system(MEIS-Ship) for graphic description of marine information and optimal route planning of ships. Also, it uses of satellite communication system for data transfer. The marine environmental components of winds, waves, air pressures and storms are provided, in which winds are described by speed and direction and waves are expressed in terms of height, direction and period for both of wind waves and swells. The real-time information is characterized by 0.5° resolution, 10 day forecast in 6 hour interval and daily update. The statistic information of monthly average and maximum value expected for a return period is featured by 1.5° resolution and based on 15 year database. The MEIS-Ship include an editing tool for route simulation and the forecasting and statistic information on planned routes can be displayed in graph or table. The MEIS enables for navigators to design an optimal navigational route that minimizes probable risk and operational cost.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.30 no.2
• /
• pp.84-94
• /
• 2018

In order to overcome the limitation of deterministic forecast, an ensemble forecasting system for regional ocean wave is developed. This system predicts ocean wind waves based on the meteorological forcing from the Ensemble Prediction System for Global of the Korea Meteorological Administration, which is consisted of 24 ensemble members. The ensemble wave forecasting system is evaluated by using the moored buoy data around Korea. The root mean squared error (RMSE) of ensemble mean showed the better performance than the deterministic forecast system after 2 days, especially RMSE of ensemble mean is improved by 15% compared with the deterministic forecast for 3-day lead time. It means that the ensemble method could reduce the uncertainty of the deterministic prediction system. The Relative Operating Characteristic as an evaluation scheme of probability prediction was bigger than 0.9 showing high predictability, meaning that the ensemble wave forecast could be usefully applied.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.12 no.4
• /
• pp.251-261
• /
• 2007

The wind-wave interaction around the Kyung-gi Bay, Korea, was studied using the observed data from ocean buoy at DeuckJeuck-Do from Jan. to Dec., 2005, and from waverider data at KeuckYeulBee-Do on Mar. 19-26 and May 23-28, 2005. Wind-driven surface waves and wave-driven wind speed decrease were estimated from the ocean buoy data, and the characteristics of wave spectrum response were also investigated from the waverider data for the wave developing and calm stages of sea surface, including the time series of spectrum pattern change, frequency trend of the maximum energy level and spectrum slope for the equilibrium state range. The wind speed difference between before and after considering the wave effect was about $2ms^{-1}$ (wind stress ${\sim}0.1Nm^{-2}$) for the wind speed range $5-10ms^{-1}$ and about $3ms^{-1}$ (wind stress ${\sim}0.4Nm^{-2}$) for the wind speed range $10-15ms^{-1}$. Correlation coefficient between wind and wave height was increased from 0.71 to 0.75 after the wave effect considered on the observed wind speed. When surface waves were generated by wind, the initial waves were short waves about 4-5 sec in period and become in gradual longer period waves about 9-10 sec. For the developed wave, the frequency of maximum energy was showed a constant value taking 6-7 hours to reach at the state. The spectrum slope for the equilibrium state range varied with an amplitude in the initial stage of wave developing, however it finally became a constant value 4.11. Linear correlation between the frictional velocity and wave spectrum for each frequency showed a trend of higher correlation coefficient at the frequency of the maximum energy level. In average, the correlation coefficients were 0.80 and 0.82 for the frequencies 0.30 Hz and 0.35 Hz, respectively.