• Title, Summary, Keyword: Korean Wave

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Extreme and Freak Wave Characteristics in the Coastal Writers of Korean Peninsula (한국 연안의 극히 파랑환경과 Freak Wave의 특성에 관한 연구)

  • 류청로;윤홍주
    • Journal of Environmental Science International
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    • v.2 no.3
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    • pp.235-243
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    • 1993
  • Extreme environments and freak wave characteristics in the coastal waters of Korean Peninsula are analyzed using the observed wave data. Freak wave has been intensely emphasized as an important environmental force parameter in several recent research works. However, the mechanism and occurrence probability of freak wave are not clarified. The aims of this study we: to summarize the distribution of extreme environment for wind waves, and to find occurrence probability of freak wave in the coastal waters of Korean Peninsula. These extreme sea conditions are discussed by applying extreme value analysis method, and the statistic characteristics are summarized which can be used to the design and analysis of coastal structures. The mechanism and the occurrence probability of freak wave are also discussed in detail using wave parameters in considered with wave deformation in the coastal waters. Key Words : extreme wave, freak wave, extreme analysis, design wave, probability density.

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A Study on the Characteristics of Large Amplitude Ocean Waves (대진폭 해양파의 특성에 대한 연구)

  • Kim, Do-Young
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.12 no.2
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    • pp.61-67
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    • 2009
  • In this paper time series wave data which contain a freak wave is investigated. Various wave characteristics are compared between wave data with a freak wave and without. Among 24 hour wave data measured in the Yura Sea, two adjacent 30 min wave data with and without a freak wave are examined intensively. It is seen that the highest waves do not have the longest wave period. The wave period of the longest period waves is a little longer than the average wave period and much shorter than the significant wave period. Although the sea state is quite high, the Rayleigh distribution fits well to the probability of wave height. The characteristics of the wave spectra do not change much, but the nonlinearity increases for the wave data with a freak wave. The significant wave height without a freak wave is larger than that with a freak wave. Hence, the higher significant wave height does not always increase the probability of the occurrence of the freak waves.

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Joint inversion of Love Wave and Rayleigh Wave for Evaluating the Subsurface Stiffness Structure (지반 강성구조 평가를 위한 러브파와 레일리파의 동시역산해석)

  • Joh, Sung-Ho;Lee, Il-Wha
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.302-307
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    • 2005
  • Love wave and Rayleigh wave are the major elastic waves belonging to the category of the surface wave. The fact that Love wave is not contaminated by P-wave which makes Love wave superior to Rayleigh wave and other body waves. Therefore, the information that Love wave carries is more distinct and clearer than the information of Rayleigh wave. Based on theoretical research, the joint inversion analysis which is used both Love wave dispersion information and Rayleigh wave dispersion information was proposed. Purpose of the joint inversion analysis is to improve accuracy and convergency of inversion results utilizing that frequency contribution of each wave is different. This analysis technique is consisted of the forward modeling using transfer matrix, the sensitivity matrix determined to the ground system and DLSS(Damped Least Square Solution) as a inversion technique. The application of this analysis was examined through the field test.

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Wave Modeling for Low-cost Wave Monitoring System (저가형 해파 모니터링 시스템을 위한 파형 모델링)

  • Lee, Jung-Hyun;Lee, Dong-Wook;Heo, Moon-Beom
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.3
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    • pp.383-388
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    • 2014
  • This paper describes a wave modeling method using low-cost sensors. Wave modeling is applied to the wave monitoring system for accurate measurement of ocean wave parameters. The observation of ocean wave parameters is necessary to improve the accuracy of forecast of ocean wave condition. However, the ocean wave parameters measured by a low-cost wave monitoring system suffer from several errors. Therefore we introduce a wave modeling method to compensate the ocean wave parameters corrupted by errors. The proposed method is analyzed using experiments within controlled environment. It is verified that the accuracy of low-cost wave monitoring system can be increased by the proposed method.

Performance Analysis of Floating Wave Energy Converter by Using CFD (CFD를 이용한 부양식 파력발전 장치의 성능해석)

  • CHOI, Yong-Seok;LIM, Tae-Woo;KIM, You-Taek
    • Journal of Fisheries and Marine Sciences Education
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    • v.27 no.5
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    • pp.1303-1309
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    • 2015
  • The behavior and flow characteristics of the floating wave energy converter were analyzed by using CFD in this study. The average significant wave height was confirmed as 0.5~2.0m from the Korean coastal sea area. This study was carried out by selecting a range of 1.0~1.6m in the wave height to simulate the operations of realistic wave energy converter system. The principle of a piston wave maker was applied in order to produce periodic wave. The behavior of the wave energy converter and the state of the wave overtopping according to the generated periodic wave were confirmed through the unsteady three-dimensional flow analysis. It was found that the wave overtopping rate according to the generated periodic wave was in range of the 11.6~30.0 kg/s.

A Numerical Study on Pontoon Type Floating Breakwaters in Oblique Waves

  • Kim, Do-Young
    • International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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    • v.3 no.1
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    • pp.23-28
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    • 2000
  • A numerical investigation was made to examine characteristics of rectangular pontoon type floating breakwaters in oblique waves. Sway and heave wave exciting forces, roll moment acting on the floating breakwater and three motion reponses decrease as the incident wave angle increases for the most of the wave ranges. There exists a minimum wave transmission coefficient which is a function of wave frequency. In short wave range wave transmission coefficient increases as the incident wave angle increases. In long wave range, however, wave transmission coefficient decreases as the wave incident angle increases.

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Estimation of Wave Power in Korean Coastal Waters (파랑에너지 해석 및 가용량 평가 연구)

  • 김현주;최학선;김선경
    • Journal of Ocean Engineering and Technology
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    • v.12 no.1
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    • pp.107-112
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    • 1998
  • The purpose of this study is to analyze the amount of available wave power and its characteristics related to the development of apractical system for ocean wave energy conversion in Korean coastal waters. The analysis method of wave power was established through comparison between theory and numerical simulation of deep sea wave by Inverse Fourier Transform with random phase method. Based on the results of comparison, wave power was estimated by use of data set from observed offshore and coastal waves and hindasted deep sea waves around the Korean peninsula. Annual mean wave power is estimated as about 1.8 ~ 7.0 kW for every metre of wave frontage at East sea, 1.5~5.3 kW at South sea and 1.0 ~ 4.1 kW at West sea, respectively. Mean wave power along deep sea front of coastal waters of Korea amounts to about 4.7 GW. Regional distribution and seasonal variation of wave power were discussed to develop practical utilization system of wave power of not so high grade of available wave power.

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Experimental Study of Deep-Water Wave Instability : Part 2. Evolution of The Initially-Modulated Wave Train (심해파의 불안정성에 관한 실험 연구 -제2부 : 초기변형파의 불안정성)

  • Cho, Won Chul
    • Journal of The Korean Society of Civil Engineers
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    • v.13 no.1
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    • pp.203-211
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    • 1993
  • Experiment on the instability and breaking of the initially modulated deep-water wave train (in wave amplitude or in wave frequency) is performed to investigate the effect of the initial modulation on nonlinear wave evolution. Wave amplitude and frequency modulations are developed earlier and larger than in the case of the uniform deep-water wave trains. However, for small wave steepness in the initially amplitude-modulated wave train, the wave train becomes demodulated and nearly returns to the original wave form at the end of the wave evolution far downstream from the breaking region, with energy returning to the fundamental wave frequency.

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A Study on Stress Wave Propagation by Finite Element Analysis (유한요소법에 의한 2차원 응력파 전파 해석에 관한 연구)

  • 황갑운;조규종
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.12
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    • pp.3369-3376
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    • 1994
  • A finite element program for elastic stress wave propagation is developed in order to investigate the shape of stress field and analysis the magnitude of stress wave intensity at time increment. Accuracy and reliance of the finite element analysis are acquired when the element size is smaller than the product of the stress wave speed and the critical value of increasing time step. In the finite element analysis and theoretical solution, the longitudinal stress wave is propagated to the similar direction of impact load, and the stress wave intensity is expressed in terms of the ratio of propagated area. The direction of shear wave is declined at an angle of 45 degrees compared with longitudinal stress wave and the speed of shear wave is half of the longitudinal stress wave.

Optimal Wave Source Position Determination Based on Wave Propagation Simulation (전자파 영향 평가를 통한 최적의 전파 기지국 위치 결정 방법)

  • 박성헌;박지헌
    • Korean Management Science Review
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    • v.18 no.1
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    • pp.41-54
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    • 2001
  • In this paper, we proposed a method to determine optimal wave source for mobile telephone communication. The approach is based on wave propagation simulation. Given a wave source we can determine wave propagation effects on every surfaces of wave simulation environment. The effect is evaluated as a cost function while the source’s position x, y, z work as variables for a parameter optimization. Wave propagated 3 dimensional space generates reflected waves whenever it hits boundary surface, it receives multiple waves which are reflected from various boundary surfacers in space. Three algorithms being implemented in this paper are based on a raytracing theory. If we get 3 dimensional geometry input as well as wave sources, we can compute wave propagation effects all over the boundary surfaces. In this paper, we present a new approach to compute wave propagation. First approach is tracing wave from a source. Source is modeled as a sphere casting vectors into various directions. This approach has limit in computing necessary wave propagation effects on all terrain surfaces. The second approach proposed is tracing wave backwards : tracing from a wave receiver to a wave source. For this approach we need to allocate a wave receiver on every terrain surfaces modeled, which requires enormous amount of computing time. But the second approach is useful for indoor wave propagation simulation. The last approach proposed in this paper is tracing sound by geometric computation. We allow direct, 1-relfe tion, and 2-reflection propagation. This approach allow us to save in computation time while achieving reasonable results. but due to the reflection limitaion, this approach works best in outdoor environment.

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