• Journal of Korean Society of Coastal and Ocean Engineers
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• v.6 no.2
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• pp.150-156
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• 1994

Shoreline change due to the littoral drift in Suyeong bay, especially the Gwanganri and Haeundae beaches, was investigated. Average monthly frequency. speed. and direction of winds blowing from between east and south for the last 15 years were analysed, and offshore significant waves were hindcasted using the JONSWAP model. Wave refractions, shoaling, and breaking weir also investigated for the calculation of littoral drift. At the Gwanganri beach major longshore transport of sands occurs from the southwest to the northeast and the shoreline seems to advance in the northeast while it recedes in the southwest. At the Haeundae beach the sands mainly move from the east to the west and the shoreline retreats in the east and advances in the west.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.175-180
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• 2006

This study is carried out the investigation of nonlinear characteristics of the ocean based on the field wave observation data acquired the western sea area in Jeju island during one year. It is aimed to offer the fundamental data for Freak wave forecasting in real sea. For this, the nonlinearity parameters of ocean waves, which are Skewness, Atiltness, Kurtosis and Spectrum band width parameter, are introduced, and the parameters are compared and discussed with some characteristic wave components, ie, significant wave height, maximum wave height, and so on.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.255-255
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• 2015

지진해일은 주기가 긴 파랑으로 방파제나 방호구조물에 의한 에너지 감소가 작은 특성이 있다. 또한, 범람구역의 구조물 밀집도 및 지형적 요인에 따라 범람영역, 침수심, 파력 등이 상이하게 나타나므로 유체흐름의 입체적 변화양상을 고려하여야 한다. 본 수리모형실험은 임원항을 대상으로 구조물에 작용하는 지진해일의 파력특성을 3차원수리모형실험을 통해 검토하고, 파력산정계수(${\alpha}$)를 제시한다. 3차원 수리모형실험은 1983년 동해 중부 지진해일 발생 시 국내에서 가장 큰 피해를 입은 임원항을 대상으로 배후부지의 구조물과 인근 해안의 지형을 1/100으로 재현하여 실험에 임하였다. 입사파랑은 고립파(solitary wave)로 재현하였으며, 천수(shoaling)에 의한 파고변화를 측정하고 그에 따른 배후부지의 침수심, 구조물에 작용하는 파력을 측정하였다. 분석된 파력 산정계수(${\alpha}$)는 임원항 인근 해역 및 배후부지의 방재대책 수립을 위한 기초자료로 활용될 것으로 판단된다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.4
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• pp.342-354
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• 2008

Some statistical characteristics of deepwater waves along the Korean coast have been investigated using various sources of wave measurement and hindcasting data. For very large waves comparable to design waves, it is recommended to use the average value of the empirical formulas proposed by Shore Protection Manual in 1977 and by Goda in 2003 for the relation between significant wave height and period. The standard deviation of significant wave periods non-dimensionalized with respect to the mean value for a certain significant wave height varies between 0.04 and 0.21 with a typical value of 0.1 depending upon different regions and different ranges of significant wave heights. The mean and standard deviation of the principal deepwater wave direction are presented at the 106 coastal grid points along the Korean coast. For relatively large waves, the probability density function of the directional spreading parameter $s_{max}$ is expressed as a lognormal distribution. The most suitable frequency spectrum in the Korean coast is the TMA spectrum. The probability density function of the peak enhancement factor $\gamma$ is also expressed as a lognormal distribution, with its mean value of 2.94, which is close to the value in the North Sea.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.2
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• pp.81-95
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• 2014

In the present study, the statistical analysis on the storm waves in the East Sea have been carried out, and the several storm waves were reproduced by the modified WAM as a first step for the accurate and prompt forecasting and warning against the swell waves in East Sea. According to the present study, the occurrences of the storm waves from the North were the most probable, while the waves from the Northeast were most frequently observed. It was found that the significant wave heights of storm waves from the North and Northern northeast were larger than those of storm waves from the Northeast. But due to long fetch distance, the significant wave periods of storm waves from the Northesast were longer than those of North and Northern northeast. In addition to the wave analysis, the numerical experiments for the storm waves in East Sea were carried out using the modified WAM, and three periods of storm waves in 2013 were calculated. The numerical results were well agreed with wave measurements. However the numerical simulation results in shallow water region showed lower accuracies compared to deep water, which might be due to lower resolution of wind field and bottom topography caused by large grid size, 5 minute, adopted in the present study. Overall computational efficiency of the modified WAM found to be excellent compared to original WAM. It is because the modified WAM adopted the implicit scheme, thereby the present model performed 10 time faster than original WAM in computation time.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.1 s.104
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• pp.39-44
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• 2006

This paper proposes a method of moments(MoM)/Monte-Carlo simulation and Physical Optics(PO) model to determine Bistatic Coherent Reflectivity of sea surfaces at various wind speeds. For the MoM simulation, a Gaussian random rough sea surface was generated based on the data of Tae-An ocean at various wind speeds and sea surface heights. The numerical results of the MoM/Monte Carlo simulations were used to verify the validity region of the PO model. It was found that the numerical result for a flat surface agrees quite well with the Fresnel reflection coefficient. The validity of the PO model on the rough sea surface is shown by using ray tracing method.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.1
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• pp.25-38
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• 1993

Numerical models of directional wave spectra for the analysis of offshore structural cable responses are verified. Alternative spreading models are used to predict wave-induced flows in water and for mooring systems. Hydrodynamic wave forces upon cable are estimated. using a Morison formula encompassing considerations for drag and for inertial forces both parallel and tangential to the slope of the cable. Numerical analysis for directional random waves. including consideration of displacement and velocity, trajectory, phase plane response. and tension are shown for mooring system cable responses at both the tether point for a buoy and at the anchor point. The effects of wave forces far different drag coefficients, various significant wave heights, and selected wave parameters are considered in the analysis. For the specific systems considered in the examples, it is demonstrated that wave period and height as well as wave spreading function parameters and drag coefficients, have an important effect upon the dynamic responses of the cable-buoy systems.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.1
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• pp.34-39
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• 2013

In this study, the quantitative analysis and pattern analysis of the error bounds with respect to recording period were carried out using the wave climate data from coastal areas. Arbitrary recording periods were randomly sampled from one month to six years using the bootstrap method. Based on the analysis, for recording periods less than one year, it was found that the error bounds decreased rapidly as the recording period increased. Meanwhile, the error bounds were found to decrease more slowly for recording periods longer than one year. Assuming the absolute estimate error to be around 10% (${\pm}0.1m$) for an one meter significant wave height condition, the minimum recording period for reaching the estimate error for Sokcho and Geoje-Hongdo stations satisfied this condition with over two years of data, while Anmado station was found to satisfy this condition when using observational data of over three years. The confidence intervals of the significant wave height clearly show an increasing pattern when the percentile value of the wave height increases. Whereas, the confidence intervals of the mean wave period are nearly constant, at around 0.5 seconds except for the tail regions, i.e., 2.5- and 97.5-percentile values. The error bounds for 97.5-percentile values of the wave height necessary for harbor tranquility analysis were found to be 0.75 m, 0.5 m, and 1.2 m in Sokcho, Geoje-Hongdo, and Anmado, respectively.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.04a
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• pp.99.1-100
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• 2003

키토산처리 콩나물에서 발아율이 높고 배축의 신장도가 높은 현상을 조사하기 위하여 전보에서와 동일한 방법으로 콩에 0.05% 키토산(493kDa, 금호화성, 한국)을 함유하는 0.05% 초산 용액 4배량을 가하여 8시간 침지한 후 2$0^{\circ}C$에서 2시간 간격으로 5일간 주수하면서 콩나물, 자엽, 배축으로 구분하여 전당, 환원당, 비환원당 및 유리아미노산의 함량변화를 조사하였다. 콩나물의 전당은 대조구, 키토산 처리구가 모두 성장에 따라 감소하였는데 대조구(1196$\longrightarrow$820 mg/100 g-f.w)보다 처리구(1241$\longrightarrow$670 mg/100 g-f.w)에서의 감소율이 높았다. 자엽의 전당함량은 성장에 따라 감소하였으며 키토산 처리구에서 현저하였고, 배축에서는 증가하는 경향을 나타내었다. 환원당 함량은 콩나물의 성장에 따라 감소하였으며 키토산 처리에 따른 뚜렷한 차이가 없었다. 그러나 자엽에서는 성장에 따라 감소하였으며 감소경향은 키토산처리구에서 높았다. 키토산 처리구에서 전당과 환원당의 감소율이 대조구보다 높은 현상은 키토산 처리에 의하여 생체 대사가 보다 활성화되기 때문이라 생각되며, 키토산처리에 의하여 발아율이 높고, 배축의 신장도가 높은 현상과 관련이 있는 것으로 판단된다. 유리아미노산은 재배 5일째 자엽과 배축의 유리아미노산 함량을 분석한 결과 aspartic acid의 함량이 가장 많았으며, 대조구의 경우 자엽에서는 25.4 mg/100 g-f.w, 배축에서는 88.2 mg/100 g-f.w이었다. 키토산처리구의 경우는 자엽에서는 23.12 mg/100 g-f.w, 배축에서는 120.18 mg/100 g-f.w이었다.높은 항 곰팡이 활성을 나타내었다. 이 외에도 황련의 물 추출물은 M. miehei 균주에서 우수한 항 곰팡이 활성을 나타내었다. 생약재의 70% Ethanol추출물을 농도별로 제조하여 항 곰팡이 활성을 살펴 본 결과, 70% ethanol추출물에서는 계피와 파고지, 초두구, 황련이 항 곰팡이 활성이 우수하였으며, 특히 계피의 70% ethanol 추출물에서는 5가지 균종에서 모두 우수한 항 곰팡이 활성이 나타났다. 균을 제외한 5가지 균종에서 높은 항균 활성을 보였으며, 이외에 생약재는 강황, 석곡, 황련, 호장근의 70% ethanol 추출물은 4가지의 균주에 대해서 항균 활성을 나타내었다. 또한 파고지, 오미자의 70% ethanol 추출물은 3가지 균주에 대해서 항균활성을 나타냈으며, 천궁, 육두구, 오수유, 갈근, 계피, 가시오가피의 70% ethanol 추출물은 2가지 균주에 대해 항균 활성을 나타내었다. 항균활성이 우수한 생약재를 농도별로 활성을 조사한 결과, 물 추출물과 10% Ethanol 추출물 모두 낮은 농도에서도 우수한 항균활성을 나타내었다.취와 함께 점질성 갈변물질이 생성되었다. 이와 같은 결과로 볼 때, BAAG의 처리는 BAAC의 경우보다 가격은 저렴하면서도 항균력은 우수한 천연 항균복합제재로써 농산물 식품원료에 적용하여 선도유지 기간을 연장할 수 있는 효과를 기대할 수 있었다. 과일 등의 포장제로서 이용할 가능성을 확인하였다.로 [-wh] 겹의문사는 복수 의미를 지닐 수 없 다. 그러면 단수 의미는 어떻게 생성되는가\ulcorner 본 논문에서는 표면적 형태에도 불구하고 [-wh]의미의 겹의문사는 병렬적 관계의 합성어가 아니라 내부구조를 지니지 않은 단순한 단어(minimal $X^{0}$ elemen

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.142-149
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• 2019

In this study, the past erosion history and current status in the CHUNG-UI beach of Eulwang-dong, Jung-gu, Incheon-Si, South Korea were investigated and analyzed the wave with wave-induced current to investigate the causes of coastal erosion. As a result, the significant wave height ($H_{1/3}$) was in the range of 0.07~1.57 m and the mean value was 0.21 m. The maximum wave height ($H_{max}$) was in the range of 0.02-4.76m and the mean value was 0.27m. The vertical wave height and cycles were estimated through numerical model experiments of wave transformation. The 50-year frequency design wave height ranged from 0.82m to 3.75m. As a result of the experiment of wave-induced current, wave-induced current in the CHUNG-UI beach was decreased after the installation of the Detached breakwater and the Jetty. On the other hand, when the crest elevation was increased up to 5 m, there was no significant change, but when the crest elevation was increased to 8m, strong wave-induced current occurred around the submerged breakwaters due to lowered depth of water. In addition, the main erosion of the CHUNG-UI beach is due to the intensive invasion of the wave characteristics coming from the outer sea into the white sandy beach. The deformation of the wave centered on the front of the sandy beach caused additional longshore currents flowing parallel to the sandy beach and rip currents in the transverse direction, thus confirming that the longshore sediment was moved out of the front and out of the sea. The results of this study can be used as preliminary data for the recovery of the sand and the selection of efficient erosion prevention facilities.