• Title, Summary, Keyword: Korean Wave

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Design and Verification of a Wave Gauge Using Digital Images (디지털 영상을 이용한 파고계 개발 및 검증)

  • Kim Taerim
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.16 no.3
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    • pp.171-177
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    • 2004
  • A new wave gauge using digital image of waves is developed and the performances are tested by wave tank experiments. This wave gauge uses frame frequency of 1/15 sec, conversion of analog images to digital images, and large capacity of hard disk. This wave gauge measures wave heights by detecting the buoy movement automatically from the image, where the buoy moves with the same phase of water surface. The comparison of automatic measurements of wave heights to the true data is reasonable. The wave gauge can be improved to measure wave heights on shallow waters near shorelines.

Theoretical Analysis of Wave Energy Converter

  • Oh, Jin-Seok;Komatsu, Toshimitsu;Kim, Yun-Hyung
    • Journal of the Korean Society of Marine Engineering
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    • v.32 no.1
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    • pp.169-174
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    • 2008
  • Floating devices, such as a cavity resonance device take advantage of both the water motion and the wave induced motions of the floating body itself. The wave energy converter is known commercially as the WAGB(Wave Activated Generator Buoy) and is used in some commercially available buoys to power navigation aids such as lights and horns. This wave energy converter consists of a circular floatation body which contains a vertical center pipe that has free communication with the sea. A theoretical analysis of this power generated by a pneumatic type wave energy converter is performed and the results obtained from the analysis are used for a real wave energy converter for buoy. This paper presents the analysis results and the design method for the WEC(Wave Energy Converter), and the associate results are application to the commercially available WEC for buoy. Maximum performance of WEC occurs at resonance with driving waves. The analysis of WEC is performed with LabVIEW program, and the design method of WEC for buoy is suggested in this paper.

Spatial Symmetry Breaking in the Revival Wave of the Belousov-Zhabotinsky Reaction Containing 1,4-Cyclohexanedione

  • Basavaraja, C.;Kim, Na-Ri;Park, Hyun-Tae;Huh, Do-Sung
    • Bulletin of the Korean Chemical Society
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    • v.30 no.4
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    • pp.907-912
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    • 2009
  • Complex breakup behavior in the revival wave has been observed in the Belousov-Zhabotinsky(BZ) reaction system containing 1,4-cyclohexanedione (1,4-CHD) in the dish divided into two compartments with a sliding window. A same reaction mixture is poured into the two compartments individually with time difference. Wave propagation exhibited different behavior in the revival wave of the reaction system. This was largely dependent on the progress time prior to the pouring into each compartment and on the gap between the times of pouring into the two compartments. The revival wave in the reaction system is induced spontaneously as a new wave train with a long time lag after the disappearance of the initially induced wave. A thoroughgoing study of the chaotic breakup of propagating chemical wave train was to be possible since the revival wave has a longer wavelength, clearer wave-train patterns, and longer duration period.

An Experimental Study on Development of Wave Absorber (소파장치 개발에 관한 실험적 연구)

  • 이희성;박준수;권순홍
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.210-214
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    • 2000
  • This paper proposes a new wave absorber made of flexible net structures. The motivation of this research is that the wave absorbers which already invented are not effective in small wave flume. The proposed new wave absorber demonstrated its efficiency when used in small-length wave flume.

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Development of Long Period Wave Observation System based on GPS (GPS 신호를 이용한 장주기 파고 관측 시스템 개발)

  • Kim, Tae-Hee;Gang, Yong-Soo;Lee, Won-Boo;Kim, Dae-Hyun
    • Journal of the Korean Society of Marine Engineering
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    • v.35 no.5
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    • pp.682-689
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    • 2011
  • Recently, there are frequent disasters by Swell-like Wave in the coastal area, Korea peninsula. This phenomenon (Swell-like Wave) has long period above 10 seconds compared with wind wave. To prevent these disasters by the long-period wave in advance, it's necessary to observe it in real time. But existing instruments for wave observation can not observe long-period wave because they mainly are aimed to measure the short-period wind wave. Therefore, in this research it is tried to develop the GPS based Long Period Wave Observation System which real time operation can be realzied in the sea.

Estimation of Design Wave Height for the Waters around the Korean Peninsula

  • Lee, Dong-Young;Jun, Ki-Cheon
    • Ocean Science Journal
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    • v.41 no.4
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    • pp.245-254
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    • 2006
  • Long term wave climate of both extreme wave and operational wave height is essential for planning and designing coastal structures. Since the field wave data for the waters around Korean peninsula is not enough to provide reliable wave statistics, the wave climate information has been generated by means of long-term wave hindcasting using available meteorological data. Basic data base of hindcasted wave parameters such as significant wave height, peak period and direction has been established continuously for the period of 25 years starting from 1979 and for major 106 typhoons for the past 53 years since 1951 for each grid point of the North East Asia Regional Seas with grid size of 18 km. Wind field reanalyzed by European Center for Midrange Weather Forecasts (ECMWF) was used for the simulation of waves for the extra-tropical storms, while wind field calculated by typhoon wind model with typhoon parameters carefully analyzed using most of the available data was used for the simulation of typhoon waves. Design wave heights for the return period of 10, 20, 30, 50 and 100 years for 16 directions at each grid point have been estimated by means of extreme wave analysis using the wave simulation data. As in conventional methodsi of design criteria estimation, it is assumed that the climate is stationary and the statistics and extreme analysis using the long-term hindcasting data are used in the statistical prediction for the future. The method of extreme statistical analysis in handling the extreme vents like typhoon Maemi in 2003 was evaluated for more stable results of design wave height estimation for the return periods of 30-50 years for the cost effective construction of coastal structures.

The Phase-velocity Dispersion Characteristics of Love Wave and Rayleigh Wave in the Half Space and Multi-layered System (반무한체와 다층구조 지반에서 러브파 및 레일레이파의 위상속도 분산특성)

  • 이일화;조성호
    • Journal of the Korean Geotechnical Society
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    • v.20 no.1
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    • pp.61-73
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    • 2004
  • Rayleigh wave and Love 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 makes Love wave superior to Rayleish wave and other body waves. Therefore, the information that Love wave carries is more distinct and clearer than the information of Rayleigh wave. In this study, for the purpose of employing Love wave in the SASW method, the dispersion characteristics of the Love wave were extensively investigated by the theoretical, numerical and experimental approaches. The 2-D and 3-D finite element analyses for the half space and two-layer systems were performed to determine the phase velocities from Love wave as well as from both the vertical and the horizontal components of Rayleigh wave. Also, the SASW measurements were performed at the geotechnical sites to verify the results obtained by the numerical analysis. The results of the numerical analysis and the field testing indicated that the dispersion characteristics of Love wave can be an extended information to make better evaluation of the subsurface stiffness structure by SASW method.

Wave Energy Distribution at Jeju Sea and Investigation of Optimal Sites for Wave Power Generation (파력발전 적지 선정을 위한 제주 해역 파랑에너지 분포특성 연구)

  • HONG KEY-YONG;RYU HWANG-JIN;SHIN SEUNG-HO;HONG SEOK-WON
    • Journal of Ocean Engineering and Technology
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    • v.18 no.6
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    • pp.8-15
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    • 2004
  • Wave power distribution is investigated to determine the optimal sites for wave power generation at Jeju sea which has the highest wave energy density in the Korean coastal waters. The spatial and seasonal variation of wave power per unit length is calculated in the Jeju sea area based on the monthly mean wave data from 1979 to 2002 which is produced by the SWAN wave model simulation in prior research. The selected favorable locations for wave power generation are compared in terms of magnitude of wave energy density and distribution characteristics of wave parameters. The results suggest that Chagui-Do is the most optimal site for wave power generation in the Jeju sea. The seasonal distribution of wave energy density reveals that the highest wave energy density occurs in the northwest sea in the winter and it is dominated by wind waves, while the second highest one happens at south sea in the summer and it is dominated by a swell sea. The annual average of wave energy density shows that it gradually increases from east to west of the Jeju sea. At Chagui-Do, the energy density of the sea swell sea is relatively uniform while the energy density of the wind waves is variable and strong in the winter.

Analysis of Long-Term Wave Distribution at Jeju Sea Based on SWAN Model Simulation (SWAN모델을 이용한 제주해역 장기 파랑분포 특성 연구)

  • Ryu Hwangjin;Hong Keyyong;Shin Seung-Ho;Song Museok;Kim Do Young
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.7 no.3
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    • pp.137-145
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    • 2004
  • Long-term wave distribution at Jeju sea is investigated by a numerical simulation based on the thirdgeneration wave model SWAN (Simulating WAves Nearshore). The Jeju sea which retains relatively high wave energy density among Korean coastal regions is considered to be a suitable site for wave power generation and the efficiency of wave power generation is closely related to local wave characteristics. The monthly mean of a large-scale long-term wave data from 1979 to 2002, which is provided by Korea Ocean Research & Development Institute. is used as the boundary condition of SWAN model simulation with 1km grid. An analysis of wave distribution concentrates on the seasonal variation and spatial distribution of significant wave heights, mean wave directions and mean wave periods. Significant wave heights are higher in winter and summer and the west sea of Jeju appears relatively higher than east's. The highest significant wave height occurs at the northeast sea in winter and the second highest significant wave height appears at the southeast sea in summer, while the significant wave heights in spring and autumn are relatively low but homogeneous. The distribution of wave directions reveals that except the rear region influenced by wave refraction, the northwest wave direction is dominant in summer and the southeast in winter. Wave periods are longer in summer and winter and the west sea of Jeju appears relatively longer than east's. The longest wave period occurs at the west sea in winter, and in summer it appears relatively homogeneous with a little longer period at the south sea.

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On statistical Properties of the Extreme Waves (극한파의 통계적 특성에 대한 연구)

  • Ryu, Hwang-Jin;Kim, Do-Yong
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.309-316
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    • 2003
  • In this paper, The statistical properties of ocean waves in the sea area of Hong-do, Korea are examined based on 1998-2002's wave data from a directional wave buoy. Wave data aquisition rate, mean wave heights, frequency of wave direction are summarized. Wave height and period scatter diagrams and n-years return period wave heights are estimated. Wave periods of maximum wave heights are also estimated. Large amplitude wave characteristics during the typhoon Prapiroon in 2000, Rusa in 2002 are also examined.

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