• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.373-381
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• 2017

Kyeonggi Provincial Government is considering double decker bus service to solve the problem of heavy rush hour traffic. However, the height-to-width ratio is more than 1.16 times larger than that of a general high-speed single decker bus, and the center of gravity is higher. This could cause driving stability problems, such as turnover and breakaway from the lane, especially under strong side-wind conditions at high speed. In this numerical study, the driving characteristics of a model double decker bus were reviewed under side-wind and superelevation conditions at high driving speed. The rolling, pitching, and yawing moment of the model bus were calculated with CFD numerical simulation, and the results were compared to the recovery angular moments of the model bus to evaluate the dynamic stability under given driving conditions. As the model vehicle moves on a straight level road, it is stable under any side-wind conditions. However, on a curved road under side-wind conditions, it could reach unstable conditions dynamically. There is a chance that the bus will turn over when it moves on a curved road with a radius of gyration less than 100 m under side-wind (15 m/s). However, there is a very small chance of breakaway from the lane under any driving conditions.

• Journal of Navigation and Port Research
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• v.33 no.8
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• pp.549-554
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• 2009

Wind velocity and wind direction are very important in the viewpoint of ship's safety and stability of port structure. The characteristics of wind distribution in the coast of Busan are analyzed for 10 years from 1997 to 2006 using AWS(Automatic Weather System) data. The characteristics of wind distribution of Miryang, is not affected by the land and sea breeze are also examined to understand clearly the characteristics of wind distribution in the coast of Busan. The mean wind velocity in the coast of Busan is stronger than that of Miryang. The mean wind velocitie at Youngdo and Gadukdo stations of Busan are stronger about 2.0 times than those at IlGwang, Haeundae and Daeyeon stations. The correlation a states show that the variation tendencies of monthly mean wind velocitie in the coast of Busan are very similar. The maximum monthly mean velocitie in the coast of Busan are recorded in September. This re ult is closely related to the influence of typhoon. The maximum instantaneous wind velocitie are also strong at Youngdo and Gadukdo stations and the peaks of maximum instantaneous wind $velocit^9$ are observed mainly from August to September. In the coast of Busan, the SW'ly-NNE'ly wind are prevailing in the winter and the SW'ly and NE'ly wind are predomi snt in the spring. w that the vs of wind direction in the summer and athumn are similar with those in the spring and winter, respectively.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.5
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• pp.340-350
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• 2020

A rapid refresh wave forecasting system has been developed using the sea wind on the Korea Local Analysis and Prediction System. We carried out a numerical experiment for wind-wave interaction as an important parameter in determining the forecasting performance. The simulation results based on the seasons of with typhoon and without typhoon has been compared with the observation of the ocean data buoy to verify the forecasting performance. In case of without typhoon, there was an underestimate of overall forecasting tendency, and it confirmed that an increase in the wind-wave interaction parameter leads to a decrease in the underestimate tendency and root mean square error (RMSE). As a result of typhoon season by applying the experiment condition with minimum RMSE on without typhoon, the forecasting error has increased in comparison with the result without typhoon season. It means that the wave model has considered the influence of the wind forcing on a relatively weak period on without typhoon, therefore, it might be that the wave model has not sufficiently reflected the nonlinear effect and the wave energy dissipation due to the strong wind forcing.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.226-234
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• 2015

To provide the data necessary to determine exposure coefficients used for calculating the snow load acting on a greenhouse, we compared the exposure coefficients in the greenhouse structure design standards for various countries. We determined the exposure coefficient for each region and tried to improve on the method used to decide it. Our results are as follows: After comparing the exposure coefficients in the standards of various countries, we could determine that the main factors affecting the exposure coefficient were terrain roughness, wind speed, and whether a windbreak was present. On comparing national standards, the exposure coefficients could be divided into three groups: exposure coefficients of 0.8(0.9) for areas with strong winds, 1.0(1.1) for partially exposed areas, and 1.2 for areas with dense windbreaks. After analyzing the exposure coefficients for 94 areas in South Korea according to the ISO4355 standard, all of the areas had two coefficients (1.0 and 0.8), except Daegwallyeong (0.5) and Yeosu (0.6), which had one coefficient each. In South Korea, the probability of snow is greater inland than in coastal areas and there are fewer days with a maximum wind velocity > $5m{\cdot}s^{-1}$ inland. When determining the exposure coefficients in South Korea, we can subdivide the country into three regions: coastal areas with strong winds have an exposure coefficient of 0.8; inland areas have a coefficient of 1.0; and areas with dense windbreaks have an exposure coefficient of 1.2. Further research that considers the number of days with a wind velocity > $5m{\cdot}s^{-1}$ as the threshold wind speed is needed before we can make specific recommendations for the exposure coefficient for different regions.

• Journal of the Korean earth science society
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• v.26 no.3
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• pp.240-252
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• 2005

The relationships between wave and wind around the Korean Peninsula have been analyzed with the data from the buoys moored at five stations (Dugjug-do, Chilbal-do, Geomoon -do, Geoje-do, Donghae) by Korea Meteorological Administration. Generally, the relationship between wave and wind is the highest at the stations in the West Sea and the lowest at the stations in the South Sea, and the middle at the station in the East Sea. The characteristics shown at each station are as follows. Highest wave is developed at Chilbal-do with strong northwesterly wind in winter because the sea is opened in the wind direction and wave is amplified by shoaling effect. At Chilbal-do, wave directions coincide with wind directions relatively well. On the other hand, waves are not fully developed at Dugjug-do in winter due to limited fetch since the sea is blocked by Hwanghae-do in the northwest direction. The limitation in fetch is more serious at the stations in the South Sea. In the South Sea, the direction of dominant northerly wind is blocked by land so that wave heights are small even with very strong northerly wind. In the South Sea, whatever wind direction is, waves dominantly come in the direction from the East China Sea, which are from the south at Geomoon-do and the southwest at Geoje-do. At these directions, waves are coming even with weak wind. At the station in the East Sea, waves are highly developed due to vast area, but not so high as in Chilbal-do because wind and wave directions do not coincide in many cases. As shown, wind direction is important in the wave development as well as wind speed. The reason is that the fetch is determined by wind direction. In the case of long-lasted wind with fixed direction at Chilbal-do and Dugjug-do, wave directions are well coincident with wind directions and wave heights increase with response time, which is the duration between the highest wind and wave. However, in the case of disagreement between wind and wave directions at the station in the East Sea, wave heights do not increase as highly as at Chilbal-do and Dugjug-do in spite of strong wind and longer response time. The results show us that waves are highly developed with strong wind, long fetch, and long duration, and also show that wave development ratios are different at different stations due to environmental factors such as the direction towards sea or land, bottom topography, and the scales of adjacent seas.

• Computational Structural Engineering
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• v.7 no.1
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• pp.25-30
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• 1994

본 고에서는 강한 바람이나 지진에 의한 고층 구조물의 진동을 감소시키기 위하여, 능동제어장치가 효과적으로 사용될 수 있음을 보이었다. 그러나 능동제어장치를 실제 구조물에 널리 적용하기에는 아직 많은 문제점들이 남아있다. 첫째, 효과에 비해 고가의 진동제어장치가 필요하며 유지관리에도 많은 비용이 필요하다. 또한 진동제어장치가 원활히 작동하기 위해서는 계속된 에너지의 공급이 있어야 하는데, 지진과 같은 과도한 구조물의 진동시 이를 보장할 수는 없다. 그러므로 극한상황에서는 진동을 오히려 증폭시킬 수도 있다. 둘째, Control Force의 산정시 사용되는 목적함수의 가중행렬을 결정하는 정형화된 방법이 아직 존재하지 않으며 효율적인 산정을 위해서는 많은 시행착오가 필요하다. 그밖에도 복잡한 실제 구조물의 단순한 모형화에 따라서 여러 문제점들이 발생하기 쉬우며, 실제 제어시에는 시간지연효과나 측정되지 못한 거동에 의한 문제 등이 있다. 구조물의 진동 저감방안에 대한 지금까지의 연구결과로는, 일반적인 경우에 있어서는 Base Isolator와 같이 재료의 감쇠특성을 이용하는 방법이 추천되고 있으나, 현재 내진설계된 고층건물과 같은 대형 구조물의 진동제어 등의 몇몇 경우에 있어서 능동제어의 필요성이 인정되고 있다. 좀더 안정적이고 효율적인 제어기법의 개발에 의해 많은 실제 구조물에 적용 범위를 넓힐 수 있을 것으로 기대된다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.105-105
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• 2004

최근 컨테이너 크레인이 대용량화되고 사용대수가 증가하게 됨으로써 여러 가지 사고 위험과 문제점이 함께 증가하게 되었다. 대표적으로 돌풍이나 태풍으로 인해 정지해 있던 크레인이 강한 풍하중을 받게 되면 레일 상에서 컨테이너 크레인이 밀리게 되는데, 한번 밀리기 시작하면 자체의 높은 관성력으로 인하여 이를 정지시키기가 매우 힘들게 되어 대형사고로 이어질 수 있다. 실례로 2an년 태풍 매미로 인하여 부산항 컨테이너 크레인이 바람에 밀려 붕괴되는 사고가 발생하기도 하였다.(중략)

• 한국해양학회지
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• v.17 no.2
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• pp.69-73
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• 1982

Wind wave generation is generally accompanied by a strong wind drift currint near the surface. The current can not be considered irrotational. The classical eqration gorerning free surface wave is formulated on the basis of irrptationality. To deal with the situation proterly, an equation governing free surface fluctuation of small amplitude is derived when the mean flow can not be assumed irrotational. The equation encompass the [lassical one as a limiting case as expected.

• 한국해양학회지
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• v.22 no.3
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• pp.119-129
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• 1987

Sediments in the cores from the KONOD-1 area consist mainly of authigenic smectite and clinoptilolite, and terrigenous minerals of illite, chlorite, kaolinite, quartz, and plagioclase. The authigenic minerals become dominant over the terrigenous minerals with increasing depth. Clinoptilolite occurs at the deeper core depth because its formation is slower than that of smectite. The vertical distribution of minerals indicates that the eolian influence, probably in the late Oligocene, diluted the abundance if smectite in near-surface sediments. This vertical distribution pattern may also have been affected by progressive dissolution of authigenic minerals in the near surface sediments.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.148-150
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• 2015

최근 가압경수로 핵연료는 다양한 형태의 원자로의 개발 및 다양한 운전 방식을 요구한다. 장주기 운전이 가능한 고연소도 핵연료의 지속적인 성능 개선이 필요하다. 핵연료에서 가연성 중성자 흡수체(Burnable absorber-BA) 역할은 매우 중요하다. 다양한 원자로 및 다양한 운전방식을 대비하여 BA 제조에 유연성을 고려하면 핵연료 피복관 내부에 직접 코팅하는 것이 바람직하다. 이에 피복관 내부표면에 직접 금속도금이 가능 여부와 기존에 많이 사용하던 전해도금에서 발생되는 기포에 의한 불균질한 도금(핀홀) 문제점 해결 방안을 고안하였다. 본 연구에서는 초임계 이산화탄소와 전해도금액간의 초음파 교반을 통한 강한 진동에 의해 매크로 에멀젼을 형성시켜 피 도금 물질 표면에 얇은 막을 얻는 도금 방법을 적용하였다. 초임계 유체를 이용한 전해도금을 적용한 결과 균질한 얇은 도금 막을 증착 시켰으며, 기포에 의한 핀홀 현상을 억제하였다. 또한 전해도금액의 사용량을 최소화 하여 폐수 발생 문제를 개선하였다.