• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.4
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• pp.469-477
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• 2015

In this study, the characteristics of main wind direction, vertical temperature and wind speed profile near the Moseulpo airfield for HALE UAV(High Altitude Long Endurance Unmaned Aerial Vehicle) is investigated. The results are summarized as follows, main wind direction is governed by air mass according to season and local wind such as land-sea breeze. The directions of landing and take-off of HALE UAV will be selected as the south-east direction in June ~ August, north-west direction in October ~ March, and south-east direction at daytime in April ~ May, September. Annual variation of temperature at 100 hPa showed that temperature in summer season is lower than winter season. On the other hands, wind speed at 250 hPa in winter season is higher than summer season. The threshold values of temperature and wind speed for HALE UAV flight are $-75^{\circ}C$ and $90ms^{-1}$, which were determined by 5 % frequency value($1.96{\sigma}$), respectively.

• Journal of Environmental Impact Assessment
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• v.16 no.6
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• pp.503-510
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• 2007

Since 1990s many skyscrapers have been built in Seoul. However, gusty winds occur among tall buildings by descending turbulences due to the upper air blocking. This study aims to investigate the wind characteristics of skyscraper prevailing wind direction. In order to evaluate the building wind in this area, The wind speed and the wind direction were measured using propeller type RM-Young wind monitor in this study. The maximum wind speed was recorded by 15.1 m/sec and the main wind direction is WNW and NW. The ultimate purpose of this study is to figure out the phenomena of building wind impact and also to provide essential basic data for establishing proper guidelines in building wind impact assessment for skyscrapers in Korea.

• Proceedings of KOSOMES biannual meeting
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• 2003.11a
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• pp.163-166
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• 2003

The seasonal mean wind direction and wind speed in a greater coasting area are investigated using the ECMWF(European Centre for Medium-Range Weather Forecasts) data for 11 years from 1985 to 1995. In winter, the main wind direction in Korea and vicinity, Taiwan and vicinity, and the North Pacific Ocean of middle latitudes is a northwesterly wind, northeasterly wind, and westerly wind respectively. The wind speed is strongest in the East China Sea, the South China Sea, and the North Pacific Ocean of low latitudes(Beaufort wind scale 5-6). A distribution pattern of wind direction in spring and fall is similar to that in winter. Seasonal mean wind speed is strongest in winter and the next is fall. The wind speed in summer is generally weak. However, that in the Indochina and vicinity is strong by the influence of Asian monsoon.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.1
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• pp.33-38
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• 2008

To investigate the building wind characteristics of skyscraper nearby areas, two points were selected and the wind speed and the wind direction data were measured using 2-D ultrasonic anemometer and propeller type wind monitor during the winter time. The study site is Dohgok-dong, Seoul. After measurement, wind data whose speed is equal to or more than Beaufort level five were selected, classified and analyzed in terms of direction, velocity level and hourly difference. The prevailing wind point is higher than street canyon in terms of intensity and frequency. The main direction is also different. This study aims to figure out the phenomena of building wind impact and also to provide essential basic data for establishing proper guidelines in building wind impact assessment for skyscrapers in Korea.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.2
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• pp.267-275
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• 2012

In this study, normal wind load and blast wind load are modeled mathematical. And the periodical torque and bending moments transmitted to the main shaft of wind turbine are investigated. A normal wind model assumed, of which the wind velocity is increased according to the height from ground. The average values and the harmonic terms of the transmitted moments are studied on the wind direction of range $-45^{\circ}{\sim}45^{\circ}$ and the bending moment characteristics are examined, which is regarded as the main source of the misalignment of gear train. In normal wind load case, excitation frequency is 3X (X : Rotor speed). When the wind direction is $+22.5^{\circ}$, the horizontal axis of bending moment occur the 50% of main torque. This result leads to edge contact of gear teeth by shaft elastic deformation. In blast wind load case, excitation frequency are 3X,6X,9X. Additional, in the (+) direction of wind load, relative harmonic percentage is increase.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.2
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• pp.138-142
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• 2003

Influences of Ieodo Ocean Research Station(IORS) on the ambient wind field were investigated through a wind tunnel experiment. To secure accurate wind speeds and directions, distortions due to the structure itself on which wind-measuring devices are to be installed should be taken into account. It was shown that the wind speed ratio was sensitive to wind direction and measuring position rather than approaching wind speed. The wind speed ratios measured at main wind tower were more than B .0 in every approaching direction, and the distortion of wind direction was under 6$^{\circ}$.

• Wind and Structures
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• v.20 no.5
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• pp.701-718
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• 2015

The joint distribution of wind speed and wind direction at a bridge site is vital to the estimation of the basic wind speed, and hence to the wind-induced vibration analysis of long-span bridges. Instead of the conventional way relying on the weather stations, this study proposed an alternate approach to obtain the original records of wind speed and the corresponding directions based on field measurement supported by the Structural Health Monitoring System (SHMS). Specifically, SHMS of Sutong Cable-stayed Bridge (SCB) is utilized to study the basic wind speed with directional information. Four anemometers are installed in the SHMS of SCB: upstream and downstream of the main deck center, top of the north and south tower respectively. Using the recorded wind data from SHMS, the joint distribution of wind speed and direction is investigated based on statistical methods, and then the basic wind speeds in 10-year and 100-year recurrence intervals at these four key positions are calculated. Analytical results verify the reliability of the recorded wind data from SHMS, and indicate that the joint probability model for the extreme wind speed at SCB site fits well with the Weibull model. It is shown that the calculated basic wind speed is reduced by considering the influence of wind direction. Compared to the design basic wind speed in the Specification of China, basic wind speed considering the influence of direction or not is much smaller, indicating a high safety coefficient in the design of SCB. The results obtained in this study can provide not only references for further wind-resistance research of SCB, but also improve the understanding of the safety coefficient for wind-resistance design of other engineering structures in the similar area.

• KIEAE Journal
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• v.4 no.3
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• pp.195-202
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• 2004

This study focuses on the impacts of apartment building arrangements on the outdoor and indoor air quality - the efficiency of natural ventilation in the outside/inside area of an apartment with consideration to the characteristics of an air flow in outside area depending on the types of the arrangements, the main direction of the wind, and the outside wind pressure on the building facade. As indices to evaluate the efficiency of natural ventilation, the concepts of "Age of Air" and "Purging Flow Rate(PFR)" were used in this study. As indices to classify the efficiency of indoor natural ventilation, the mean values of the wind pressure differences between the front and the back elevations of an apartment building were used. The research showed that the PFR of each apartment building arrangement ranges from 0.867 to 3.253. The "minus-shaped" arrangement showed the highest PFR, 2.306; the "zigzag-shaped" arrangement measured 1.889; the "angle-shaped" arrangement measured 1.465, and the "square-shaped" arrangement measured 1.241. Depending on the direction of the wind, the pressure differences range extremely, with variations from 170% to 2300%. Thus, the indoor natural ventilation efficiency can be changed by the pressure differences of the wind, which are sensitive to the main direction of the wind even though the structure and planning of the apartment complexes are the same. Despite the same direction of the wind, even the efficiency can be diverse. This study showed how to predict the most beneficial apartment building arrangement for the profitable natural ventilation efficiency in each direction of the wind.

• Journal of the Korean housing association
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• v.18 no.2
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• pp.105-112
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• 2007

This research has been implemented based on the area of #369 Dowon-dong, Dalseo-gu, Dae-gu which is considered as a place with satisfactory characteristics for the flow of fresh air into the city. Simulations of the target area both prior to the development plan and after apartment complex blocking were analyzed in regard to blocking planning and pilotis based on the main direction of wind, $90^{\circ}$ (east wind) and $180^{\circ}$ (south wind). In addition, congested wind corridor flow in the target place was identified through a pollution spread simulation according to the wind corridor. Therefore, the flow of wind in the one area is affected by the blocking of the complex and the main direction of the wind. Also blocking, in regard of pilotis, provides a better flow of wind. This study was implemented based on wind formation by apartment complex planning, so further study on the other factors affecting the flow of a wind corridor along with block planning and pilotis need to be carried out. Sustainable environmental factors through analysis of the environmental factors have to be analyzed. Moreover, building and complementing fundamental resources and systematic devices should be supported.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.7
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• pp.521-530
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• 2009

This study has been made to execute a research in order to lead the improvement of indoor air quality, examining the indoor ventilation characteristics by using a numerical analysis method. To this end an extensive parametric investigation are made according to various external flow variables such as main wind direction and wind speed by season, building layout design, and location of ventilators, etc. in Daedeok Techno Valley, one of large-scaled apartment in Daejeon. It is observed there was a significant difference of main wind direction between summer and winter. The main wind direction in summer was a south wind, and on the contrary the direction in winter is northnorthwest, which is similar to the average main wind direction for 10 years. One of the important calculation results is that the change of wind direction causes a significant effect on the apartment ventilation by the change of pressure difference around each complex of apartment. In case of favorable area of ventilation, the indoor ventilation rate can meet 0.7 ACH from the standard value only with natural ventilation. On the contrary, in other area the value was much lower than the standard value. If the calculation result applies to the design of layout apartment or placement of ventilators, it will be greatly helpful to the energy saving because it can be parallel with the natural ventilation to help securing ventilation rate, not much depending on the mechanical ventilation.