• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.1
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• pp.36-45
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• 2017

In the present study, the storm waves at the Korean Straits of April, 2016 have been reproduced by the wave hindcasting, and then their characteristics were investigated. Before the wave hindcasting, the wave measurements at the Korean Straits were analyzed. The analysis showed that the waves at the Korean Straits were dominated by the Northeastern waves, same as those in the East Sea. Accordingly, the wave hindcasting was been carried out with the same condition in Ahn et al. (2016). In the numerical results, the maximum significant wave height at the Korean Straits was 5.06 m, and the corresponding significant wave period was 9.2 s. The computed significant wave heights and wave periods were overestimated by 4 cm and 0.8 s, respectively. After the wave hindcasting, the computed significant wave heights and peak periods were compared with the JONSWAP relationship. This comparison showed that the storm waves at the Korean Straits were close to wind waves, not swell.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.36 no.2
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• pp.61-69
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• 2024

Wave conditions are crucial for offshore wind farm design, particularly in determining structural loads and layout. However, there is limited wave hindcasting research for the Wangdeungdo Island area, a potential offshore wind site. This study used the MIKE21 model for a year-long wave hindcast around Wangdeungdo in 2021. Validation showed high reproducibility for significant wave heights with RMSE values of 0.177 and 0.225 and Pearson correlations of 0.971 and 0.970 at Sangwangdeungdo and Buan buoys. Subsequent analysis of the wave characteristics near Wangdeungdo indicated significant seasonal variations and differences in maximum significant wave heights across locations, which are expected to significantly impact the design loads for offshore wind structures.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1996.10a
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• pp.34-37
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• 1996

해상풍에 의한 파랑의 발달을 다룬 모델은 1940년대 이후 실측파랑 및 기상자료로부터 이론에 기초한 경험식이 제시되었다. 이러한 경험식들은 실제의 불규칙한 해면상태를 유의파로 대표하여 유의파의 파고 및 주기를 풍속, 취송거리 및 취송시간의 함수로 나타낸 것이다. 널리 쓰이고 있는 심해에서의 모델은 SMB법과 Wilson법이 있으며 일정한 바람이 연속적으로 불어오는 안정된 정상상태에서는 SMB법이, 그리고 풍역이 시간적 공간적으로 변화가 큰 경우에는 Wilson법이 적용되고 있다. (중략)

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.200.1-200
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• 2003

본 연구에서는 식품의 부패에 관여하는 미생물인 Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureu, Salmonella typhimurium Lactobacillus plantarum에 항균 활성을 나타내는 생약제의 효능을 살펴보았다. 금산 약초시장에서 구입한 생약재로부터 물 추출물과 70%에탄을 추출물을 제조하여 6종의 세균에 대해 항균활성을 탐색한 결과, 생약재 물 추출물의 경우에 가자 추출물은 E. coli, P. aeruginosa B. subtilis, S. aureus, S. typhimurium, L. plantarum의 6가지 균종에 대해서 모두 높은 항균활성을 나타내었으며, 복분자와 지유의 물추출물에서는 L. plantarum의 균종을 제외한 5가지 균종에 대해 높은 항균 활성을 나타내었다. 또한 소목 과 황련의 추출물에서는 E. coli를 제외한 5가지 균종에서 항균활성을 나타내었으며, 정향 추출물에서는 E. coli균주에 대해서는 약한 항균활성을 나타내었으나, B. subtilis, P. aeruginosa, S. aureus, S. typhimurium의 4종의 균주에 대해서는 우수한 항균활성을 나타내었다. 이 외에 감초 추출물은 P. aeruginosa, 석곡 추출물은 S. aureus, S. typhimurium, 계피 추출물은 S. typhimurium, 산수유 추출물은 B. subtilis, S. aureus, 파고지는 S. aureus균종에 대해서 항균활성을 나타내었다. 70% ethanol 추출물은 대부분의 생약재에서 높은 항균 활성을 나타내었다. 특히 가자, 감초, 강황, 복분자, 석곡, 소목, 오미자, 작약 ,정향, 지유, 파고지, 호장근, 황련 의 13가지 생약재 추출물에서 높은 항균활성을 나타내었다. 가자의 70% ethanol추출물의 경우는 물 추출물의 결과에서 같이 6가지 균종에 대해 모두 높은 항균활성을 나타냈으며, 복분자, 작약, 정향, 지유의 70% ethanol 추출물은 L. plantarum균을 제외한 5가지 균종에 대해 높은 항균 활성을 나타내었다. 소목의 70% ethanol 추출물의 경우에는 E. coli 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.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.4
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• pp.329-335
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• 2007

The eye measurement to observe the sea surface condition and estimate the wave height has been used in the open sea or the ship. The experts in the eye estimation can measure the wave height very accurately. The Beaufort wind scale is most widely used as a standard index of the eye measurement. However, more definite reference data such as the representative images by each wave heights must be necessary because the appearances and explanations in the Beaufort wind scale are not enough to understand the sea surface condition far the researcher and the public. The modern field data acquisition technique has been developed to measure wave heights, ocean weather data and even images of the sea surface in real-time. In this study, the wireless field image transmitting system for wave heights and images is installed in the real-time ocean measurement system of Chodo light tower near Sokcho city in South Korea. The wave heights and surface images acquired from the real time system in the field are compared with explanations of the Beaufort wind scale. The wave heights and images measured with the precision ultrasonic wave sensor and the scientific sea surface image transmitting system should be helpful to obtain more precise and definite information than the data from the Beaufort wind scale.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.3
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• pp.130-141
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• 2004

For a coastal or harbor structure design, one of the most important environmental factors is the appropriate design wave condition. Especially, the information of deepwater wave height distribution is essential for reliability design. In this paper, a set of deep water wave data obtained from KORDI(2003) were analyzed for extreme wave heights. These wave data at 67 stations off the Korean coast from 1979 to 1998 were arranged in the 16 directions. The probability distributions considered in this research were the Weibull, the Gumbel, the Log-pearson Type-III, and Lognormal distribution. For each of these distributions, three parameter estimation methods, i.e. the method of moments, maximum likelihood and probability weighted moments, were applied. Chi-square and Kolmogorov-Smirnov goodness-of-fit tests were performed, and the assumed distribution was accepted at the confidence level 95%. Gumbel distribution which best fits to the 67 station was selected as the most probable parent distribution, and optimally estimated parameters and 50 year design wave heights were presented.

• Journal of the Korean earth science society
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• v.25 no.4
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• pp.277-288
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• 2004

In this study, state of sea surface were analyzed comparatively for cases of low atmospheric pressure, which occurred in the middle area of China and moved eastward to the Korean Peninsula across the Yellow sea during April 9-12, 1999, and typhoons 'NEIL' May 1999 and 'OLGA' July 1999, which moved northward along the west coast of the Korean Peninsula. In cases of low pressure, wind speeds and phases were respectively stronger and faster in the center area than in the surrounding areas. The wave heights seem to a somewhat differing tendency from that of the wind speeds due to the influences of geometry. On the other hand, wave heights were lower under typhoon weather than under low pressures, except the instance of wave height over 5 m on Chilbal when typhoon Olga pass northward from the southern area. Storm surges also showed larger amplitudes under low pressures than under typhoons. The results suggest that wave sand storm surges may be larger for a slow passing synoptic low pressures than for a fast passing local typhoon.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.4
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• pp.244-254
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• 2013

In this study, a method has been developed for estimating the change of nearshore random waves in response to sea-level rise, by extending the method proposed for regular waves by Townend in 1994. The relative changes in wavelength, refraction coefficient, shoaling coefficient, and wave height for random waves are presented as functions of relative change in water depth. The changes in wavelength and refraction coefficient are calculated by using the significant wave period and principal wave direction in the regular-wave formulas. On the other hand, the changes in shoaling coefficient and wave height are calculated by using the formulas proposed for shoaling and transformation of random waves in the nearshore area including surf zone. The results are proposed in the form of both formulas and graphs. In particular, the relative change in wave height is compared with the result for regular waves.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.1
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• pp.11-20
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• 2003

In this paper we examine several methods tor calculating the reflection of irregular waves from a perforated-wall caisson breakwater using a regular wave model. The first method is to approximate the irregular waves as a regular wave whose height and period are the same as the root-mean-squared wave height and significant wave period, respectively, of the irregular waves. The second is to use the regular wave model, repeatedly, for each frequency component of the irregular wave spectrum. The wave period is determined according to the frequency of the component wave, and the root-mean-squared wave height is used for all the frequencies. The third method is the same as the second one except that the wave height corresponding to the energy of each component wave is used. Comparison with experimental data from previous authors shows the second method is the most adequate, giving reasonable agreement in both frequency-averaged reflection coefficients and reflected wave spectra.

• Journal of Navigation and Port Research
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• v.27 no.2
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• pp.111-119
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• 2003

In order to improve navigational safety of ships, an ocean wave prediction model of high precision within a short time, dealing with multi-directional random waves from the information of the sea surface winds encountered at the planned ship's course, was introduced for construction of ocean wave forecasting system on the ship. In this paper, we investigated a sea disaster occurred by a stormy weather in the past. We analyzed the sea surface wind first and then carried out ocean wave hindercasting simulations according to the routes the sunken vessel. From the result of this study, we concluded that the sea disaster was caused by rapidly developed iou pressure system Okhotsk Sea and the predicted values by the third generation wave prediction model(WAM) was agreed well with the observed significant wave height, wave period, and directional wave spectrum. It gives a good applicability for construction of a practical on-board calculation system.