• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.44-44
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• 2011

저수지와 같은 갇혀진 수체는 상류에서 유입되는 오염물질 뿐만 아니라 성층현상에 의해서도 오염될 수 있다. 안정된 성층은 혐기성 조건을 제공하여 바닥에서의 과도한 조류성장을 유발하고 연직순환흐름을 방해한다. 갇혀진 수체에서의 연직순환은 환경적인 문제를 감소시킬 수 있도록 중요한 역할을 한다. 갇혀진 수체에서의 연직순환은 이러한 오염을 줄이는데 중요한 역할을 하는데, 연직순환을 일으키는 인자로는 빛의 입사, 바람, 물의 온도 및 열의 확산 등이 있으며, 그중에서도 가장 중요한 것은 바람의 영향이다. 그러므로 성층화된 흐름에서 바람에 의해 발생하는 연직순환에 대한 수치모형을 개발하고 적용하는 것이 필요하다. 본 연구에서는 수온성층흐름에서의 순환흐름을 해석하기 위하여 유속성분을 계산하고 자유수면 변위와 온도, 염도등과 같은 스칼라양의 해석을 위해 다음과 같은 3단계의 방법을 이용하였다. 첫 번째 단계(정수압 계산단계)에서는 운동량 방정식의 경사항을 음해적으로 해석하고, 두 번째 단계(자유수면 보정단계)에서는 자유수면의 변화를 계산하고 수평방향 유속성분을 계산한다. 예측-수정자 방법(predictor-corrector step method)을 이용하여 자유수면변위와 유속을 구하였다. 마지막으로 세 번째 단계(이송-확산단계)에서는 이송-확산 방정식을 이용하여 스칼라양을 계산하였다. 본 연구에서 제시한 모형의 정확도를 검증하기 위하여 정사각형수조에서 진동하는 자유수면의 해석해와 비교하였고, 성층화된 흐름에서 발생하는 연직순환에 대하여 수치모의를 실시하였다. 그 결과, 본 연구에서 개발된 수치모형이 흐름 내부의 현상을 잘 묘사함을 알 수 있었다.

• Journal of Korean Society of societal Security
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• v.4 no.1
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• pp.29-37
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• 2011

Recently, Inhabitants nearby the high embankment road have requested a civil complaint on the environmental deteriorations and economic harms. This study was carried out numerical simulation using the 3-D microclimate model 'Envi-met' in order to investigate the variations of a flow field and a temperature field at the road sections with a high embankment and a bridge. About the simulation of flow field, the wind field has changed due to the disturbance of airflow by a high embankment road considerably. And the wind velocity decreased in the whole of simulation space widely. But, the wind velocity and wind direction sited loose to the section of a bridge, relatively. In the results of a temperature field, the slight variations of temperature field were discovered by the disturb of the mixing flow from a high embankment road. These results indicate that the numerical simulation can provide useful information to minimize the disasters, such as traffic accidents and various microclimatic environments in the transportation projects.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.11
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• pp.903-910
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• 2020

This paper introduces a simulator to assess the impacts of the wind and the airframe vibration on the performance of the Active Electronically Scanned Array (AESA) radar mounted in an aircraft. The AESA radar is mounted on the nose cone of an aircraft, and vibration occurs due to the drag force. This vibration affects the behavior of the AESA radar and can cause phase errors in signal. The simulator adopts the geometric model for nose cone, the mathematical models on the rigid-body dynamics of the aircraft, the average/turbulent winds, and the mode/ambient vibrations to compute the position and the attitude of the radar accurately. Numerical studies reflecting a set of test scenarios were conducted to demonstrate the effectiveness of the developed simulator.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.1
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• pp.34-46
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• 2010

We observed tidal currents throughout all four seasons in 2007 at a single station, located 1.6km off Haeundae Beach and compared these current data with wind data. The direction of seasonal wind represented a similarity between the winds at sea and on land but the speed of wind at sea was almost three times stronger than the wind on land. In addition, the wind at sea turned out to considerably affect on tidal currents, particularly from late summer to autumn. On the other hand, the thickness of Ekman Layer, indicating a limitation of wind influence, was estimated to be 31.8 m on average, suggesting that the entire water column is under the influence of wind. Therefore, we are required to consider the wind stress into the analysis of tidal currents for the prevention of the loss of sand from Haeundae Beach.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.1
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• pp.1-8
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• 2002

The effects of sideslip on the vortex over a delta wing was investigated experimentallu at a free strean velocity of 40 m/sec, corresponding to a Reynolds number of 1.76$\times$$10^6$, based on the root chord. The angles of attack ranged from $16{^{\circ}}$ to $28{^{\circ}}$, and the sideslip angles treated were $0{^{\circ}}$, $-10{^{\circ}}$, and $-20{^{\circ}}$. It was observed that the sideslip decreased the strengths of the vortices of both windward and leeward sides of the wing, and promoted the vortex breakdown on the windward side. At sideslip angle of $-10{^{\circ}}$, the vortex strength of leeward side was increased as the angle of attack increased. This asymmetric development and breakdown of vortices in sideslip condition would cause an abrubt change of the rolling moment at a high angle of of attack, which could be considered as a rolling moment instability.

• Journal of the Korean earth science society
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• v.27 no.6
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• pp.687-694
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• 2006

This paper investigated the effects of wind stress forcing in the western North Pacific on ENSO decadal change before and after the late 1970s. The SVD analysis of SODA data shows that a positive wind stress curl is dominant in the western North Pacific at the ENSO mature phase, which leads to the ENSO phase change by discharge/recharge heat contents in the equatorial Pacific. Before the late 1970s, the wind stress curl in the western North Pacific was strong. This strong wind forcing that is associated with the fast discharge of heat contents in the equator led to the short period and the weak intensity of ENSO occurred during the 1960-1970. On the other hand, after the late 1970s the relatively weak wind stress curl was accompanied with the long period and the strong intensity of ENSO. The simple coupled model experiments also confirm that the amplitude and dominant period of ENSO decrease when the wind stress curl in the western North Pacific projects more strongly into the ocean at the TNSO mature phase. Our results support that the changes in the behavior of ENSO after the late 1970s are associated with the wind stress variation in the western North Pacific.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.12
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• pp.899-907
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• 2022

According to the Unmanned aircraft system Traffic Management (UTM), drones are permitted to fly up to 150m above ground, which is located in the atmospheric boundary layer where there is considerable wind fluctuation due to turbulence. Although it is difficult to predict when turbulence will occur drone aviation safety could be enhanced by having a better understanding of the characteristics of vertical profile of wind in the flight area. We used wind lidar (WIndMast 350M) to observe vertical profiles of wind at the test site for aviation meteorological observation equipment located near Incheon International Airport in July and September, 2022. In this study, we utilized the observed wind profile data to propose a technique for obtaining information that could help improve the drone aviation safety. The Fourier transform analysis is used to evaluate the temporal characteristics of the horizontal wind speed at various vertical levels up to 350m. We also examined the relative contribution of the variance of wind having scales of less than an hour, a crucial scale for drone flight, to the variance of wind having all scales at each vertical altitude for days with and without precipitation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.415-426
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• 2023

In this study, the horizontal and vertical structure of wind speed and wind direction were analyzed at the origin of migratory insect pests in China. Wind rose analysis was carried out using the Land-Atmosphere Modeling Package (LAMP) - WRF data, which has the spatiotemporal resolution of about 20 km and 1 hour intervals. Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) was employed for backward trajectory analysis between South Korea and Southeastern China with Global Data Assimilation System (GDAS). The research interest date is July 16, when rice planthopper and leafhopper were observed at the same time. In order to examine where a jet stream occurs in the vertical in source regions and South Korea during the period (July 8 to July 17 in 2021), three-dimensional wind information was extracted and analyzed using the east-west, north-south, and vertical component wind data of the LAM P. The vertical distribution of wind showed that the wind changed in favor of the inflow of migratory insect pests during the period. As a result of analyzing the wind rose, about 30% or more of the wind at a point close to South Korea was classified into the low-level jet stream. In addition, majority of the wind directions for the low-level jet streams (rather than high-level jet streams) at the five origin sites were heading toward South Korea and even Japan, and this was supported by the HYSPLIT-based backward trajectory analysis.

• The Monthly Diabetes
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• s.219
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• pp.11-14
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• 2008

탄수화물은 에너지의 주 공급원으로 혈당에 가장 큰 영향을 미치는 영양소이다. 먹는 양에 비례해서 혈당을 상승시키므로 한 번에 많은 양을 섭취하는 것은 바람직하지 않으며, 혈당 조절을 위해 탄수화물의 양을 잘 조절해야한다. 탄수화물이 혈당에 미치는 영향은 섭취하는 탄수화물의 양이 가장 중요하지만, 탄수화물의 종류에 따라서도 혈당 반응의 차이가 있기 때문에 탄수화물의 종류와 특성을 이해하고, 혈당이 천천히 덜 올라가는 탄수화물을 선택하는 것이 중요하다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1742-1743
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• 2011

항해 중인 선박에 가장 영향을 미치는 것은 해양파이다. 해양파는 주로 바람에 의해서 생성이 되며 지역적으로 바람의 세기와 방향이 다르기 때문에 파의 높이와 파의 길이가 정해져 있지 않은 불규칙파가 발생한다. 선박에 미치는 해양파의 힘에 따라 횡동요의 크기 및 주기가 달라진다. 해양파의 힘의 크기가 선박의 복원력보다 크게 되면 선박은 전복이 된다. 이런 이유로 선박 운동을 인위적으로 억제하기 위하여 Fin Stabilizer를 사용하게 되었다. Fin Stabilizer는 짧은 시간에 동작하여 선박의 안전을 향상시킬 수 있으며, 운행 효율을 높일 수 있기 때문에 최근 들어 널리 사용되고 있는 방법이다. 본 논문에서는 해양파의 힘이 선박에 영향을 미칠 때의 횡요각 변화를 관찰하고 설계한 제어기의 성능정도를 위한 Simulation을 수행하였다. Simulation 결과를 토대로 Fin Stabilizer를 제어하기 위한 Digital 제어기를 구성하였다.