• 한국철도학회논문집
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• 제10권3호
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• pp.271-277
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• 2007

The Korean Tilting Train eXpress (TTX) development program is in progress for the purpose of running speed or passenger's comfort improvement at the curved track. However, the speed up and light weight of train make poor the dynamic safety of the TTX in strong cross wind. In this paper, 3-dimensional numerical analysis on the flow field around the TTX under strong cross wind is performed for each operating condition, such as the train speed, cross wind speed, tilting/nontilting condition, and so on. Due to the strong cross wind, the pressure distribution around the train becomes asymmetric, especially at the leading car. Asymmetrical pressure distribution causes the side force and strong unstability. The side force on the train is proportional to the train speed and cross wind speed. Based on the numerical results, the overturning coefficients are predicted for investigation of the train stability, and all of them are less than the critical value, 0.9. The results in this study would be a good data for providing importance to judgement of cross wind safety of TTX.

• 대기
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• 제16권3호
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• pp.169-185
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• 2006

We have investigated the wind speed variations over the leeward region when the strong wind blows. In this study we employ Envi-met numerical model to simulate the effect of surface boundary conditions. This model is applied for three cases which are characterized by land use and terrain height. The base case having natural geographical condition shows the weakest wind speed around lee side of Chunsudae. The others which remove the vegetation and cut off the terrain above 20 m ASL represent the stronger wind speed than base case. The main factor of this result is the surface friction. The distinct variation of wind is found at offshore area between Chunsudae and the southern part of village, but the northern part where is apart from Chunsudae shows a small variation of wind pattern. The weakening of wind speed around residential area is a maximum of 4~10 m/s when the wind blows in the village as strong as 55 m/s. The gust wind speed is weakened about 7~17 m/s in this case if the coefficient of gust wind adapted as 1.75.

• 한국환경과학회지
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• 제30권9호
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• pp.753-762
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• 2021

This study analyzed the characteristics of strong winds accompanying typhoons for a period of 116 years, from 1904 to 2019, when modern weather observations began in Korea. Analysis shows that the average wind speed and high wind rate caused by typhoons were higher over the sea and in the coastal areas than in the inland areas. The average wind speed was higher over the West Sea than over the South Sea, but the rate of strong wind was greater over the South Sea than over the West Sea. The average wind speed decreased by 1980 and recently increased, while the rate of strong winds decreased by 1985 and has subsequently increased. By season, the strong winds in autumn (september and october) were stronger than those in summer (june, july, and august). Strong winds were also more frequent in autumn than in summer. The analysis of the changes in strong winds caused by typhoons since the 1960s shows that the speed of strong winds in august, september, and october has increased more recently than in the past four cycles. In particular, the increase in wind speed was evident in fall (september and october). Analysis of the results suggests that the stronger wind is due to the effects of autumn typhoons, and the increased possibility of strong winds.

• 한국환경과학회지
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• 제5권6호
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• pp.713-718
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• 1996

We identified two characteristic turbulent flow cases, weakening and strengthening, which appear at the downwind side. Observations were made two times, Dec. 2-3. 1995 and Feb. 13-14. 1996 at Pusan National University site located downwind side of Kumjeong mountain. Meteorological observation system, tethersonde, was adopted to present observation. In the case of the west wind which blows perpendicular to Sanghak mountain located westward from the site, the wind speed highly increased in exponential with height. Therefore, the low level wind speed was so weak just like Taylor(1988)'s review. While the wind speed was intensified at 200-400m layer when the northwest wind blows from the continental Siberian high. We suppose 기 is because of the strong vertical convergence of flow between the surface inversion layer and the upper one, and also the horizontal convergence along the saddle and valley between the two mountains, Kumjeong and Sanghak-because of Bernoulli's effect. The inversion layer existed at surface-l00m and 500-600m level and the strong wind existed at about 200-400m layer.

• 한국항해항만학회지
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• 제42권5호
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• pp.317-322
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• 2018

Marine weather information provided for vessels is mainly offered by radio devices such as NAVTEX, Weather Fax., and others. However, the information is too general for large areas, and lacks more detail. So, many seafarers are disinclined to use the information to initiate proper readiness of vessels' safety, avoiding marine accidents such as grounding, hull and cargo damage, but cannot develop an optimal and economical navigation plan, considering the inadequate level of low precision weather information. The purpose of this paper is to develop a strong wind warning system, based on the digital anemometer installed on the bridge. This study analyzed the data on 10-minutes average wind speed, when the vessel's grounding accidents happened in Korean ports. Results reveal that the vessel's strong wind warning algorithm, can estimate the growing of wind speed two-three hours in advance.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.231-232
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• 2023

With taller buildings and larger typhoons, the impact of building winds is growing. During the 11th Typhoon Hinnamno in 2022, the building wind in Busan L City exceeded 60m/s, reaching the highest speed ever. Although many studies have been conducted on reducing the wind load of buildings, which is one of the problem factors caused by strong wind speed, there is a lack of research on wind speed reducing sculptures that can directly control strong wind speed. In this paper, several types of wind speed reduction sculptures were proposed to solve these problems, and the wind speed reduction capability of the proposed sculptures was analyzed through computational fluid dynamics (CFD). These results can contribute to suggesting effective design methods for improving the urban environment and reducing pedestrian stress.

• 대기
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• 제18권4호
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• pp.493-506
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• 2008

In order to examine the variational features of Asian dust outbreak in recent years, observed WMO synop data were employed for the period from 1996 to 2007. We first divided Asian dust source regions into four subregions; 1) Taklamakan, 2) Gobi, 3) Inner Mongolia-Manchuria and 4) Loess, and the meteorogical variables such as wind speed, precipitation and threshold wind speed observed during the Asian dust outbreak period were compared with those during non-Asian dust period. The results showed that temporal variation of occurrence frequency of dust outbreak had a strong positive correlation with the frequency of strong wind speed and low precipitation in each of the 4 source regions. Spatial distributions of frequency of dust occurrence after 2002 showed increasing trend in Gobi and Inner Mongolia-Manchuria but decreasing trend in Loess region. This is showing a shift in main source region toward Northwest, especially since 2003.

• 한국방재학회 논문집
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• 제9권4호
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• pp.37-44
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• 2009

본 연구에서는 1970년부터 2008년까지 연중 강풍 발생이 많은 지역인 군산, 목포, 여수, 완도에서 관측된 시간별 평균 바람자료를 이용하여 원인별 강풍발생특성을 분석하였다. 기상청 강풍주의보 기준인 13.9 m/s 이상인 바람을 강풍으로 정의하였다. 강풍 발생 원인을 태풍, 겨울 계절풍, 전선풍으로 구분하였다. 태풍의 경우 관측지점 상륙을 전후로 급격한 풍향 및 풍속의 변화를 나타냈고, 겨울 계절풍의 경우에는 북서풍 계열이 우세하며 풍속의 주기성을 보였다. 전선풍은 전선의 위치에 따라 관측지점의 풍향이 남서풍 계열에서 북서풍 계열로 변화하였다. 강풍의 발생빈도는 군산, 목포, 여수, 완도의 순이었고, 발생 원인별로 겨울 계절풍은 군산과 목포, 완도에 가장 영향이 크고, 태풍의 영향이 가장 적었으며, 여수는 태풍에 의한 영향이 가장 많고 겨울 계절풍의 영향이 가장 적었다. 지구온난화와 연관된 강한 태풍의 발생은 매년 태풍의 수가 일정함에도 불구하고 강풍 발생빈도를 증가시켰으며, 겨울 계절풍과 전선풍에 의한 빈도는 점차 감소하는 경향을 보였다. 강풍의 지속시간의 결과에서는 각 발생원인 모두 1시간 지속시간의 비율이 가장 높고, 시간이 증가할수록 빈도는 감소하였다. 이러한 결과는 각 지점의 지리적 위치에 의한 영향이 크게 반영되어 나타났다.

• 전기학회논문지
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• 제66권12호
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• pp.1799-1803
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• 2017

This paper introduces the prediction methods of windstorm advisory using GP nonlinear compensation and SVM. The existing special report prediction is not specialized for strong wind, such as windstorm, because it is based on the wide range of predicted values for wind speed from low to high. In order to improve the performance of strong wind reporting prediction, a method that can efficiently classify boundaries of strong wind is necessary. First, evolutionary nonlinear regression based compensation technique is applied to obtain more accurate values of prediction for wind speed using UM data. Based on the prediction wind speed, the windstorm advisory is determined. Second, SVM method is applied to classify directly using the data of UM predictors and windstorm advisory. Above two methods are compared to evaluate of the performances for the windstorm data in Jeju Island in South Korea. The data of 2007-2009, 2011 year is used for training, and 2012 year is used for test.

• 대기
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• 제30권1호
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• pp.47-57
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• 2020

In this study, the climatological spatio-temporal variation of strong wind and gust wind in Korea during the period from 1993 to 2018 was analyzed using daily maximum wind speed and daily maximum instantaneous wind speed data recorded at 61 observations. Strong wind and gust wind were defined as 14 m s^-1 and 20 m s^-1, which are the same as the KMA's criteria of special weather report. The frequency of strong wind and gust wind occurrence was divided into regions with the higher 25 percent (Group A) and the lower 75 percent (Group B). The annual frequency of strong wind and gust wind occurrence tended to be decreased in most parts of the Korean peninsula. In Group A with stations located at coastal region, strong wind and gust wind occurred most frequently in winter with higher frequency at 1200~1600 LST and 2300~2400 LST due to influence of East Asian winter monsoon. In addition, a marked decreasing trend throughout the four seasons was shown at Daegwallyeong, Gunsan and Wando observations. In contrast, it can be found in Group B that the monthly frequency of strong wind and wind gust occurrence was higher in August and September by effect of typhoon and hourly frequency was higher from 1200 LST to 1800 LST.