• 동력기계공학회지
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• 제13권2호
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• pp.63-70
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• 2009

This paper discusses the influence on long-tenn predictions of the ship response in ocean by using the Global Wave Statistics data, GWS, and wave information from the remote sensing satellites. GWS's standard scatter diagrams of significant wave height and zero-crossing wave period are suggested to be corrected to a round number of 0.01/1000 fitted with a statistical analytic model of the conditional lognormal distribution for zero-crossing wave period. The GEOSAT satellite data are utilized which presented by I. R. Young and G. J. Holland (1996, named as GEOSAT data). At first, qualities of this data are investigated, and statistical characteristic trends are studied by means of applying known probability distribution functions. The wave height data of GEOSAT are compared to the data observed onboard merchant ships, the data observed by measure instrument installed on the ocean-going container ship and so on. To execute a long-tenn prediction of ship response, joint probability functions between wave height and wave period are introduced, therefore long-term statistical predictions are executed by using the functions.

• 한국해양공학회지
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• 제32권2호
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• pp.123-130
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• 2018

The present study investigated the validity of an equilibrium shoreline empirical formula for real phenomena. Among three types of equilibrium shoreline formulas, Hsu's parabolic type static formula was employed, which is well-known and the most practical for shoreline estimation after coastal or harbor structure construction. The wave data observed at Maengbang beach and the CERC formula on longshore sediment transport were used in the present investigation. A comparison study was only conducted for the case of a shoreline change after the construction of a groyne. Reasonable agreement was seen between the observed wave data and the data obtained under a wave angle spreading function S = 3.5. However, significant changes were observed when S increased. Thus, careful application is required when using Hsu's formula.

• 한국해양공학회지
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• 제22권6호
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• pp.13-19
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• 2008

Abnormally large swells that appeared on the coast of the East Sea in October in 2005 and 2006 were simulated using SWAN model to examine the accuracy of the model for future forecasting Seawind data calculated based on the weather chart ant bottom topography were used for input data, and the model was operated more than 20 days before the observed swells to avoid the problems from the cold start of the model. The comparisons with observed wind and wave data were unsatisfactory and neededmore improvement in terms of swell component in the wave model as well as the quality of seawind data. The satellite wind and wave data can be good candidates for future comparison of the wave model results in the East Sea.

• 한국환경과학회지
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• 제32권11호
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• pp.841-852
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• 2023

In this study, the significant wave height and wave period of a specially designed observation system that connected two drifting buoys to an ocean data buoy was observed for 23 days from February 7 to 29, 2020, and the results were compared and analyzed. The results indicated that, in comparison to the ocean data buoy, the drifting buoy exhibited greater variability in significant wave height over shorter time intervals. The wave period of the ocean data buoy also appeared longer than that of the drifting buoy. The greater the observed significant wave height and wave period from both the ocean data and drifting buoys, the more pronounced the differences between the two observation instruments become. Moreover, the study revealed that the disparity in observation methods between the ocean data and drifting buoys did not significantly affect the significant wave height characteristics, as long as the period remained unchanged for up to half of the observation time.

• 한국수산과학회지
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• 제30권1호
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• pp.16-30
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• 1997

Application of digital filter to the wave analysis is studied using the observed data by wave gauge. Sea wave data obtained from wave gauge always include long wave frequency components. In order to estimate the sea wave parameters, we must re-analyzed wave data by using a digital filter and the concept of mean sea level correction method. By the wave by wave analysis and spectral methods, sea wave parameters on the basis of wave data obtained by the conventional method and digital filter are compared. The best-fitted design filter determined by the necessary conditions of frequency responses, can be obtained by calculating various transfer functions. Thus, to get the best the digital filter design, both Butterworth filter and Savitzky-Golay filter of digital filter are used in the frequency and time domain, respectively. Three cases of observation wave data are calculated by applying digital filter. The components of different frequency bands in the surf zone are coexisted in three cases. The wave data for wind wave components is computed using the digital filter the surf zone and off-surf zone, and based on the filtered data, wave parameters are calculated by the spectral analysis and wave by wave analysis methods, respectively. As a results, when sea wave data observed by wave gauge are analyzed, the Savitzky-Golay method is recommended which can well appear cut-off frequency by experimental choosing filter length in the time domain. The better mean sea level correction method is the Butterworth filter in the frequency domain.

• 대한원격탐사학회지
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• 제28권1호
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• pp.95-100
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• 2012

큰 너울은 먼 해역에서 발생한 후 우리나라 해안에 전파하여 피해를 입히는 경우가 많다. 이를 방지하기 위해서는 우리나라 인근 해역에서 뿐만 아니라 외해역에서도 파랑 관측이 이루어져야 하지만 현장 관측의 경우 많은 비용 및 장비 망실 위험 때문에 어려움이 따른다. 위성의 고도계를 활용할 경우 우리나라 동해 중앙 해역이나 외해 그리고 타 국가의 해역과 같이 접근이 어려운 해양에서 파랑을 관측하는 일이 가능하다. 그러나 이에 앞서서 고도계 파랑 자료의 정확도를 검증하는 것이 필요하다. 본 연구에서는 ENVISAT 위성의 고도계 파고 자료와 이어도 기지에서 관측한 파랑 자료를 비교 분석 한 후 그 활용성을 검토한다.

• 한국해안·해양공학회논문집
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• 제28권4호
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• pp.212-221
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• 2016

본 연구에서는 동해안에 고파가 내습한 시점을 대상으로 관측 파랑자료와 미국 국립해양대기청(NOAA)에서 추산한 기상 예측자료를 통합 분석하였으며, 기상예측자료를 이용한 동해안 파랑예측시스템을 구축하였다. 또한, 파랑 예측결과를 관측자료와 비교하여 적용성을 확인하였다. 동해안 연안에는 2회 파고가 증가하고 2차 파고 증가 시 연안 기상조건은 양호한 경우도 있어 피해가 우려된다. 2008년 2월에 관측된 파랑 관측자료를 이용하여 고파의 전파방향을 추정하였으며, 기상자료와 비교를 통해 2번째 증가시기 파랑의 발생역이 동해 연안에서 멀리 떨어진 러시아와 일본 사이 해역임을 확인하였다.

• 한국연안방재학회지
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• 제4권1호
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• pp.7-19
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• 2017

In this study, waves and currents observed by acoustic AWAC, VECTOR and Aquadopp Profiler in Anmok coastal waters were analysed to account for the variability of wave and current and to understand the mechanism of sediment transport generated by wave-induced current in the surf-zone. The monthly variation of wave and residual currents were analysed and processed with long-term observed AWAC data at station W1, located at the water depth of about 18m measured during from February 2015 to September 2016. Wave-induced currents were also analysed with intensive field measurements such as wave, current, suspended sediment, and bathymetry data observed at the surf-zone during in winter and summer. The statistical result of wave data shows that high waves coming from NNE and NE in winter (DEC-FEB) are dominant due to strong winds from NE. But in the other season waves coming from NE and ENE are prevalent due to the seasonal winds from E and SE. The residual currents with southeastern direction parallel to the shoreline are dominant throughout a year except in winter showing in opposite direction. The speed of ebb-dominant southeastern residual currents decreasing from surface to the bottom is strong in summer and fall but weak in winter and spring. By analysing wave-induced current, we found that cross-shore current were generated by swell waves mainly in winter with incoming wave direction about $45^{\circ}$ normal to the shoreline. Depending on the direction of incoming waves, longshore currents in the surf-zone were separated to southeastern and northwestern flows in winter and summer respectively. The variation of observed currents near crescentic bars in the surf-zone shows different direction of longshore and cross-shore currents depending on incoming waves implying to the reason of beach erosion generating the beach cusp and sandbar migration during high waves at Anmok.

• 한국해안·해양공학회논문집
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• 제26권3호
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• pp.149-159
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• 2014

본 연구에서는 속초 인근의 파향 파고계로 관측된 파랑 자료를 이용하여 동해안 주요지역에 너울성 고파를 예측하는 알고리즘을 개발하였다. SWAN 모형을 이용하여 연안의 파랑 관측 자료로부터 고파 발생지로 예상되는 외해지점의 파랑 제원을 추정하였다. 추정된 파랑 제원을 경계조건으로 쓰고 SWAN 모형과 파향선 추적법을 사용하여 동해안 주요지역에서의 너울성 고파를 예측하였다. 왕돌초에서 관측한 파랑 자료를 예측 결과와 비교하여 예측알고리즘의 정확성을 검증하였다. 동해안 실시간 파랑관측 시스템과 본 연구결과를 활용하면 동해안 너울성 고파를 보다 정확하게 예측할 수 있다.

• 한국해양공학회지
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• 제38권3호
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• pp.103-114
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• 2024

Remote sensing wave observation data are crucial when analyzing ocean waves, the main external force of coastal disasters. Nevertheless, it has limitations in accuracy when used in low-wind environments. Therefore, this study collected the raw data from MIROS Wave and Current Radar (MWR) and wave radar at the Ieodo Ocean Research Station (IORS) and applied the optimal filter by combining filters provided by MIROS software. The data were validated by a comparison with South Jeju ocean buoy data. The results showed it maintained accuracy for significant wave height, but errors were observed in significant wave periods and extreme waves. Hence, this study used an artificial neural network (ANN) to improve these errors. The ANN was generalized by separating the data into training and test datasets through stratified sampling, and the optimal model structure was derived by adjusting the hyperparameters. The application of ANN effectively improved the accuracy in significant wave periods and high wave conditions. Consequently, this study reproduced past wave data by enhancing the reliability of the MWR, contributing to understanding wave generation and propagation in storm conditions, and improving the accuracy of wave prediction. On the other hand, errors persisted under high wave conditions because of wave shadow effects, necessitating more data collection and future research.