• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3A
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• pp.209-216
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• 2009

The structural stability as well as economical efficiency of the wind sensitive structures are strongly dependant on accurate evaluation of the design wind speed. Present study demonstrates a useful wind data obtained at the wind monitoring tower in the Kwangyang Suspension Bridge site. Moreover the Measure-Correlate-Predict (MCP) method has been applied to estimate the long-term wind data at the bridge site based on the wind data at the local weather station. The measured data indicate that the turbulent intensities and roughness exponents are strongly affected by the wind direction and surrounding topography. The new design wind speed based on MCP method is 20m/s lower than that at the original estimation, and the resulting design wind load is only 36% of the old prediction. The field measurement of wind data is recommended to ensure the economical and secure design of the wind sensitive structures because the measured wind data reveal much different from the estimated one due to local topography.

• Water for future
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• v.21 no.4
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• pp.389-397
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• 1988

For determination of the design wves at the seven selected sites in the South Sea, a method of hindcasting the past annual largest significant waves from the records of both the wind speed at the nearby weather stations and the weather charts of typhoons are utilized. The design significant waves in deep water are determined through the extremal probability analysis for three major wave directions(SW, S, SE) at each site from the annual extremal series of wave heights. Design significant wave heights with the return period of 100 years ranged between 4.6m and 8.8m with the wave period ranging between 8.2 seconds and 12.9 seconds. Through the analysis of weather maps, both the fetches for the wind directions SW-SE along the South Coast and the relationship between the wind speed at sea and the wind speed at the nearby land weather stations for seasonal winds are determined. The wind speed at sea are found to be 0.8-0.9 times the wind speed at the land stations for $U_1$>15m/s. The ratio of the duration-averaged wind speed to the maximum wind speed varies between 0.7-0.9 as a negative exponential function for the duration ranging 2< t< 13 hours.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.153-160
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• 2011

Recently there are many long span cable supported bridges like Cable Stayed Bridge and Suspension Bridge already constructed or planned. Reconsidering of proper design wind load of long span bridge is required since the meteorological value based on the data only from 1960s to 1995 has been used when we estimate the wind load for designing long span bridges. In this paper, the research area was confined to western and southern coasts where many long span bridges have constructed. The method of moment and the least-squares method were used to estimate the expected wind speeds of 100 year's return period for girder bridges and for 200 year's return period for long span bridges based on the Gumbel's distribution. As the return-period wind speed on the land face was revised because of recent high speed velocity, the revised return-period wind speed is increased by 17%. Compatibility of return-period wind speed was also evaluated using RMS (Root Mean Square) error method. Aa a result of this paper, the least-squares method is more compatible than the method of moment in the case of western and southern coasts in Korea.

• New & Renewable Energy
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• v.7 no.1
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• pp.15-21
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• 2011

In recent years, many countries have been endeavoring to exploit the offshore wind energy in terms of overcoming the limitations of on-land wind energy. Considering that mountains cover 70 percent of the Korean Peninsula and arable plains for wind energy are negligibly small, Korean government aggressively drives the offshore wind development of the Korean Peninsula. As part of preliminary investigation of offshore wind resources, KEPCO-RI (Korea Electric Power Corporation-Research Institute) has been analyzing marine buoy datasets measured at 5 positions over the period of 12 years, including estimation of extreme wind speed. It can be observed that variation of yearly wind speed, monthly wind speed as well as frequency distribution of wind direction. Wind classes of buoy sites are estimated by extrapolated average wind speed using log law. In addition, wind turbine class based on IEC code is assessed for evaluation of suitable wind turbine.

• Journal of Korean Society of Steel Construction
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• v.21 no.6
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• pp.553-561
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• 2009

Risk analysis of highway sign supporting structures and sound barriers was done. Stochastic wind load was modeled by using extreme value distribution from site measurement and the variability of structural parameters was considered. Limit state functions were defined to assess structural stability by wind and risk of highway facilities was analyzed by combining wind hazard. According to the numerical analysis results, sound barrier post shows significantly higher risk than highway sign supporting structures. This is caused by the fact that the design codes of the structures are different. To distribute wind induced risk in highway structures, unification and improvement of design codes are required based on risk assessment.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.5
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• pp.241-252
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• 2019

To choose appropriate countermeasures against potential coastal disaster damages caused by a storm surge, it is necessary to estimate the frequency of storm surge heights estimation. As the coastal populations size in the past was small, the tropical cyclone risk model (TCRM) was used to generate 176,689 synthetic typhoons. In simulation, historical paths and central pressures were incorporated as a probability density function. Moreover, to consider the typhoon characteristics that resurfaced or decayed after landfall on the southeast coast of China, incorporated the shift angle of the historical typhoon as a function of the probability density function and applied it as a damping parameter. Thus, the passing rate of typhoons moving from the southeast coast of China to the south coast has improved. The characteristics of the typhoon were analyzed from the historical typhoon information using correlations between the central pressure, maximum wind speed ($V_{max}$) and the maximum wind speed radius ($R_{max}$); it was then applied to synthetic typhoons. The storm surges were calculated using the ADCIRC model, considering both tidal and synthetic typhoons using automated Perl script. The storm surges caused by the probabilistic synthetic typhoons appear similar to the recorded storm surges, therefore this proposed scheme can be applied to the storm surge simulations. Based on these results, extreme values were calculated using the Generalized Extreme Value (GEV) method, and as a result, the 100-year return period storm surge was found to be satisfactory compared with the calculated empirical simulation value. The method proposed in this study can be applied to estimate the frequency of storm surges in coastal areas.

• Journal of the Korean Data and Information Science Society
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• v.28 no.6
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• pp.1415-1425
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• 2017

Typhoons are accompanied by strong wind and heavy rains. It causes casualties and property damage on the Korean peninsula every year. The effect of typhoon to daily precipitation should be quantified to prevent the damage of typhoon. Daily precipitation, maximum wind speed and, mean wind speed data was collected from 60 weather stations between 1976 and 2016. The parameters of the generalized extreme value distribution were estimated through the maximum likelihood estimation and the L-moment estimation. The impact of a typhoon can be obtained through a comparison of return levels between the whole data and typhoon excluded data. We conclude that the eastern and southern coastline are exposed to the risk of heavy rainfall which is caused by typhoon.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.3
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• pp.122-134
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• 1994

The objective of this study is to provide with the hydrometeological and probabilistic characteristics of the storms and winds of typhoons that have been passed through the Korea peninsula during the last twenty-three years since 1961. The paths and intensities of the typhoons were analyzed. Fifty weather stations were selected and the rainfall and wind data during typhoon periods were collected. Rainfall data were analyzed for the patterns and probabilistic distributions. The results were presented to describe the areal distributions of probabilistic characteristics. Wind data were also analysed for their probabilistic distributions. The results obtained from this study can be summarized as follows: 1. The most frequent typhoon path that have passed through the Korean peninsula was type E, which was followed by types CWE, W, WE, and S. The most frequent typhoon intensity was type B, that was followed by A, super A, and C types, respectively. 2. The third quartile typhoon rainfall patterns appear most frequently followed by the second, first, and quartiles, respectively, in Seoul, Pusan, Taegu, Kwangju and Taejon. The single typhoon rainfalls with long rainfall durations tended to show delayed type rainfall patterns predominantly compared to the single rainfalls with short rainfall durations. 3. The most frequent probabilistic distribution for typhoon rainfall event is Pearson type-III, followed by Two-parameter lognormal distribution, and Type-I extremal distribution. 4. The most frequent probability distribution model of seashore location was Pearson type-III distribution. The most frequent probability distribution model of inland location was two parameter lognormal distribution. 5. The most frequent probabilistic distribution for typhoon wind events was Type-I xtremal distribution, followed by Two-parameter lognormal distribution, and Normal distribution.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1316-1320
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• 2009

최근 한반도지역의 시공간적 수문변화 및 지속시간 연최대강우 추세분석을 위하여 기상청에서 제공 되어지는 관측자료를 이용하여 분석을 실시하였다. 분석을 위하여 서울, 인천, 속초, 부산, 군산등 전국적인 분포를 보이는 60개소의 일강수량, 일평균기온, 일최고 및 최저기온, 일평균풍속, 일습도 자료를 수집하였다. 더불어 지속시간별 연최대강우 추세분석을 위하여 동일기간에 대한 시간자료를 수집하여 분석을 실시하였다. 일자료를 이용한 분석결과 분석기간의 년평균강수량은 1998년 이전 1342.2mm였으나, 1998년 이후는 1,511.6mm로서 최근의 강수량 증가를 확인할 수 있었다. 계절적으로는 비홍수기에 비하여 홍수기에 강수량 증가가 더욱 두드러졌으며, 수계별로는 낙동강과 섬진강의 경우가 한강과 금강등 기타 수계에 비하여 최근의 강수량 증가추세가 상대적으로 뚜렷한 것으로 분석되었다. 내륙과 해안지역의 분석결과에서는 해안지역의 년강수량이 내륙에 비하여 90mm 정도 높게 나타났으며, 지역별로는 동해안지역이 서해안과 남해안에 비하여 변화경향이 크게 나타났다. 일최고강수량 및 집중호우빈도 분석결과 수계별 분석의 경우 한강수계가 다른 수계에 비하여 상대적으로 큰 증가경향을 보였으며, 한편 섬진강수계는 다소 완만한 경향을 나타내고 있었다. 집중호우빈도 분석결과 역시 년강수량과 마찬가지로 동해안지역에서의 변화경향이 크게 나타나고 있었다. 무강수일수는 전국적으로 감소경향을 보이고 있어, 강수발생일당 강수량은 증가하는 경향을 보이고 있었다. 이러한 수문학적 변화경향을 세부적으로 살펴보기 위하여 수계별 대표지점을 선정하여 지속시간별(1hr, 2hr, 3hr, 4hr, 6hr, 12hr) 강우강도 추세분석을 실시하였다. 분석결과 지속시간에 따른 강우강도 역시 증가하는 경향을 나타내는 것을 확인하였으며 짧은 지속시간이 상대적으로 큰 증가경향을 나타내는 것으로 확인하였다. 하지만 정확한 분석을 위하여 보다 많은 관측소에 대한 추가분석이 필요할 것으로 판단되어 진다.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.126-126
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• 2023

최근 대한민국에서는 기후변화로 전국 각지에서 돌발성 호우와 태풍의 강도 및 발생빈도가 높아지고 있다. 이에 따라 주요 국가시설이 위치한 해안 도시의 2차원 3차원 모형을 통해 극한 조건하 침수 분석을 수행하였다. 먼저 해양수산부 "2019년 전국 심해설계파 보고서"를 기반으로 극치분포 중 Weibull 분포를 이용하여 극한 조건, 1,000년부터 1,000,000년 빈도의 재현기간의 파도 높이와 풍속을 계산하였다. 계산 결과를 SWAN(Simulating WAves Nearshore)의 입력값으로 해상에서 100m 간격의 파고 높이를 계산하였다. 이때 100m 간격으로는 방파제 지형을 정확히 해석하지 못하였기에, 상세파고 계산을 위한 Nesting 기법을 이용하여 20m 간격의 파고 결과를 도출하였고, 해안 도시 인근 해상에서 10.916m의 파고를 예측하였다. 또한, 예측된 파고를 이용해 EurOtop(2018) 매뉴얼의 경험식을 기반으로 연구 유역으로 유입되는 월류량 계산에 사용하였다. 결과로 16방위 중 SSE 방향, 1,000,000년 빈도 재현기간 조건에서 0.0306cms/m의 월파량을 예측했다. 예측된 자료를 바탕으로 2차원 침수해석은 FLO-2D 모형, 3차원 침수해석은 FLOW-3D 모형을 이용하였다. 2차원 침수해석 결과 주요 지점에서 0.18~0.33m의 침수가 예상되었고 3차원 침수해석 결과 동일한 지점에서 0.240~0.333m의 침수가 예상되었다. 모의 결과 2차원과 3차원 모형 간 침수 예측 결과가 0.3cm에서 6.1cm의 차이를 나타내어 모형 구축이 합리적으로 이뤄졌다고 판단하였으며 연구 유역에서는 침수가 예상된다는 결과를 도출하였다. 본 연구를 통해 기후변화에 따른 해안에 위치한 주요 도시지역과 국가 주요 시설물에 대한 침수해석을 실시하였고 분석결과를 생명과 재산을 보호하기 위한 대피계획 등 재난예방대책 수립에 활용할 수 있음으로 예상된다.