• Title/Summary/Keyword: 너울

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The Analysis of Characteristics of Swell in Korea using the Ubiquitous Measurement System (유비쿼터스 관측시스템을 이용한 국내 너울의 특성규명에 관한 연구)

  • Jang, Bok-Jin;Yeo, Woon-Kwang;Lee, Jong-Kook;Park, Kwang-Soon
    • Journal of Korea Water Resources Association
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    • v.41 no.8
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    • pp.785-795
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    • 2008
  • The swell is a major cause of interruption for the activity in a port and the ship navigation in coastal waters, coastal geographical changes, and the disaster with a loss of lives. However, many researches about the observation and the prediction of swells have not been conducted actively due to the difficulties to collect and synthesize the massive amount of long term field data for waves and meteorological information. In this study, the internet-based realtime monitoring system(Fieldbox) was developed to collect the wave data. The characteristics and main components of swells occurred in Korea were analyzed using wave data observed through the Fieldbox and the meteorological data collected by the KMA(Korea Meteorological Administration) and NASA(National Aeronautics and Space Administration). The characteristics of the swell generation patterns were analyzed using the monthly data of the Kwangan Tower between 2004 and 2006 to estimate the specific features such as sources and locations of swells generated in Korea.

Analysis of the Reason for Occurrence of Large-Height Swell-like Waves in the East Coast of Korea (우리나라 동해안 너울성 고파의 발생원인 분석)

  • Oh, Sang-Ho;Jeong, Weon-Mu;Lee, Dong-Young;Kim, Sang-Ik
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.22 no.2
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    • pp.101-111
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    • 2010
  • Characteristics of large-height swell-like waves that repeatedly occurred on the Korean East Coast in winter season were analyzed by using the wave observation data and the meteorological data. Based on the results of the data analysis, it was demonstrated that the swell-like waves have been generated due to the long-lasting strong northeasters in the East Sea, which were formed as a result of the low pressure trough in the vicinity of the extratropical low pressure system that advanced to East Sea from the China inland with decreasing its central pressure. Among the recently occurred events of the swell-like waves, the characteristics of the two events in October 2005 and 2006 were predominantly wind waves. Meanwhile, the one in February 2008 seems to be occurred by the initial wave growth due to wind waves followed by the secondly increase of the wave height due to longer-period swell.

A Study of Machine Learning Model for Prediction of Swelling Waves Occurrence on East Sea (동해안 너울성 파도 예측을 위한 머신러닝 모델 연구)

  • Kang, Donghoon;Oh, Sejong
    • The Journal of Korean Institute of Information Technology
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    • v.17 no.9
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    • pp.11-17
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    • 2019
  • In recent years, damage and loss of life and property have been occurred frequently due to swelling waves in the East Sea. Swelling waves are not easy to predict because they are caused by various factors. In this research, we build a model for predicting the swelling waves occurrence in the East Coast of Korea using machine learning technique. We collect historical data of unloading interruption in the Pohang Port, and collect air pressure, wind speed, direction, water temperature data of the offshore Pohang Port. We select important variables for prediction, and test various machine learning prediction algorithms. As a result, tide level, water temperature, and air pressure were selected, and Random Forest model produced best performance. We confirm that Random Forest model shows best performance and it produces 88.86% of accuracy

Backshore Erosion due to High Swell Waves (너울성고파랑에 기인한 후빈 배후 침식)

  • Kim, Kyu Han;Shim, Kyu Tae
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.24 no.5
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    • pp.366-371
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    • 2012
  • High swell has been known for the one of the main causes of beach erosion in the east coast of Korea. In this study, coastal topography changes due to high swells are simulated to find its effect on the backshore by using movable bed experiments and numerical experiments. Sea bottom topographical changes due to various incident waves were investigated using CSHORE model in the numerical experiments. Furthermore, the mechanism and the phenomena of beach erosion due to waves and high swells on the foreshore and backshore were analyzed and compared with movable bed hydraulic experiments.

Suppression of Swell Effect in 3.5KHz Subbottom Profiler Data (3.5KHz 천부지층탐사자료의 너울영향제거)

  • 이호영;구남형;박근필;김정기;김원식;강동효
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.7 no.3
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    • pp.95-99
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    • 2002
  • 3.5KHz subbottom profiling systems are useful for delineating of shallow (up to 10~100m below the sea bottom) geological structure. These systems are generally used to image geological structures with less than 1m of vertical resolution. However swell in the sea is quite often higher than 1m, causing degradation in the quality of the 3.5KHz subbottom profiles. In this paper, we show the quality of digitally recorded data can be enhanced by the suppression of swell effect. Prior to suppression of swell effect, sea bottom detection procedure was applied using the characteristics that the amplitude of sea bottom reflection is high. To suppress the swell effect, we applied moving average method and high-cut filtering method using the extracted water depth of adjacent traces. Acceptable results were obtained from both methods. In the case of bad quality data or shallow data interfered with direct wave, the suppression of swell effect is difficult due to incorrect sea bottom detection.

Hindcasting Analysis of Swells Occurred in the East Coast in February 2008 (2008년 2월 동해안에서 발생한 너울의 예측 분석)

  • Kim, Tae-Rim;Lee, Kang-Ho
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.15 no.2
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    • pp.62-67
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    • 2010
  • Swells occurred on the coast of the East Sea on February 24, 2008 caused a loss of three lives and also damaged several west coasts of Japan. The recent increase of swell intensity with number of accidents demands more accurate forecasting of swells in terms of time and location. The swells occurred in February 2008 are hindcasted using SWAN model to examine the accuracy of the model for future forecasting. The model results are compared with ReWW3 data as well as measurement wave data and specially, wave spectrum is analysed by comparing with observed spectrum at two wave stations located in the east coast of Korea. The SWAN model shows similar results with observation data in terms of significant wave heights and swell arrival time but the shapes of wave spectrum are different between model and in-situ measurement data. For further improvement of swell forecasting, more comparison and analysis with observed wave spectrum is necessary and wave directional spectrum data are required to study on the characteristics of swells in the East Sea.

Real-time Simulation of Seas and Swells for Ship Maneuvering Simulators (선박운항 시뮬레이터를 위한 풍파와 너울의 실시간 시뮬레이션)

  • Park, Sekil;Oh, Jaeyong;Park, Jinah
    • Journal of KIISE
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    • v.42 no.7
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    • pp.846-851
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    • 2015
  • Seas and swells are basic wave types in ocean surface simulation and are very important elements in the simulation of ocean background. In this paper, we propose a real-time simulation method, for reproducing realistic seas and swells, to be used in real-time simulators such as ship maneuvering simulators. Seas and swells have different visual properties. Swells have relatively longer wavelengths and round crests compared with seas, therefore they are visualized globally with large meshes and procedural methods. Parameters to illustrate swells are extracted from ocean wave spectra. Conversely, seas have shorter wavelengths and their characteristics are only clearly apparent near to the observation point. Here, we present visualization of seas based on a statistical wave model using ocean wave spectra, which provides realistic results in a reactively small area.

특집-일본의 재해예방대책 - 1. 너울에 대해서

  • 한국어촌어항협회
    • 어항어장
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    • s.89
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    • pp.30-34
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    • 2010
  • 너울성 거대 파랑의 내습은 극히 보기 드문 확률로 기상조건이 갖추어지고 취송거리가 지극히 길어졌을 경우에 발생하므로 해일 등의 돌발 재해와 같은 특별한 대책이 요구된다. 토야마만은 갑자기 깊어지는 만으로 "아이가메(藍甁)"라고 불리는 복잡한 해저지형을 나타내는 지역도 있어, 연안의 파랑 변형에 해저지형의 영향이 강하게 나타나고 있음이 예상된다.

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Wavelet Analysis of Swells in the East Sea (동해 너울에 대한 웨이블릿 분석)

  • Kim, Tae-Rim;Lee, Dong-Young
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.20 no.6
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    • pp.583-588
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    • 2008
  • Swell data observed in the East Sea in February, 2008 were analyzed using wavelet method. The wavelet analyzed results show detailed time series variation of wave group, peak frequency and spectrum. The comparison of time averaged wavelet spectrum with fourier spectrum turn out to be very similar in terms of spectrum shape and peak frequency evolution but the peak frequency wave energy and the significant wave height show discrepancies. Wavelet analysis can detect the change of spectrum in time as well as in frequency and very efficient to study transient and irregular phenomena such as freak waves and abnormal swells in the ocean. More analysis with more wave data are needed for future application.

Algorithm of Predicting Swell-like Significant Waves in the East Coast of Korea (동해안 너울성 고파 예측 알고리즘)

  • Ahn, Suk Jin;Lee, Byeong Wook;Kwon, Seok Jae;Lee, Changhoon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.6
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    • pp.2329-2341
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    • 2013
  • In this study, we develop an algorithm to predict swell-like significant waves in the east coast of Korea using the directional wave gauge which is installed near Sokcho. Using the numerical wave model SWAN, we estimate wave data in open sea from the wave data observed through the directional wave gauge. Then, using the wave ray method with the open-sea wave data as offshore boundary conditions, we predict the swell-like significant waves at several points in the east coast of Korea. We verify the prediction methods with the SWAN and wave ray methods by comparing numerically predicted data against either target or measured data at the observation site. We can improve the prediction of the swell-like significant waves in the east sea of Korea using both the real-time wave measurement system and the present prediction algorithm.