• Journal of Environmental Impact Assessment
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• v.30 no.4
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• pp.187-202
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• 2021

This study examined the effectiveness of wind corridor construction by analyzing the thermal environment, cold air generation, ventilation, and geographical characteristics to improve urban thermal environment and establish the basis for specialized strategy in Changwon-si, Gyeongsangnam-do. Using spatial analysis and remote sensing techniques, surface temperature, land cover and land use, wind field, and slope were measured and through this, a wind corridor analysis model was constructed. As a result of the analysis as of 2020, Changwon-si generally has land cover characteristics that are advantageous for the generation of cold air, but the temperature in most urban areas is the highest, and the temperature in areas such as north Changwon area, Jinbukmyeon, Ung-dong, and Ungcheon-dong are relatively high. There was a typical trend of high average wind speed in mountain regions and low average wind speed in urban areas. Accordingly, the north Changwon area, the former Changwon downtown area, the Hogye-ri and Pyeongseong-ri areas, and the Changpo Bay area are derived as vulnerable areas to thermal environment, and various measures to reduce temperature and improve air quality that the inflow of cold air into the area considering the characteristics of each area and securing wind ventilation between the surrounding mountains, reservoirs, and park areas were proposed.

• Wind and Structures
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• v.38 no.2
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• pp.109-118
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• 2024

A solar concentrator is a reflective surface in the shape of a parabola that collects solar rays in a focal area. This concentrator follows the path of the sun during the day with the help of a tracking system. One of the most important issues in the design and construction of these reflectors is the force exerted by the wind. This force can sometimes disrupt the stability of the concentrator and overturn the entire system. One of the ways to estimate the force is to use the numerical solution of the air flow in three dimensions around the dish. Ansys Fluent simulation software has been used for modeling several angles of attack between 0 and 180 with respect to the horizon. From the comparison of the velocity vector lines on the dish at angles of 90 to - 90 degrees, it was found that the flow lines are more concentrated inside the dish and there is a tendency for the flow to escape around in the radial direction, which indicates the presence of more pressure distribution inside the dish. It was observed that the pressure on the concave surface was higher than the convex one. Then, the effect of adding a hole with various diameter of 200, 300, 400, 500, and 600 mm on the dish was investigated. By increasing the diameter up to the optimized size of 400 mm, a decrease in the maximum pressure value in the pressure distribution was shown inside the dish. This pressure drop decreased the drag coefficient. The effect of the hole on the dish was also investigated for the 30-degree angled dish, and it was found that the results of the 90-degree case should be considered as the basis of the design.

• Wind and Structures
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• v.26 no.3
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• pp.179-190
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• 2018

Translation of tornadoes is an important feature in replicating the near-ground tornado flow field which has been simulated in previous studies based on Ward-type tornado simulators using relative motion of the ground plane. In this laboratory investigation, effects of translation on the near-ground tornado flow field were studied using the ISU Tornado Simulator that can physically translate over a ground plane. Two translation speeds, 0.15 m/s and 0.50 m/s, that scale up to those corresponding to slowly-moving tornadoes in the field were selected for this study. Compared with the flow field of a stationary tornado, the simulated tornado with translation had an influence on the spatial distribution and magnitude of the horizontal velocities, early reversal of the radial inflow, and expansion of the core radius. Maximum horizontal velocities were observed to occur behind the center of the translating tornado and on the right side of its mean path. An increase in translation speed, resulted in reduction of maximum horizontal velocities at all heights. Comparison of the results with previous studies that used relative motion of the ground plane for simulating translating tornadoes, showed that translation has similar effects on the flow field at smaller radial distances (~2 core radius), but different effects at larger radial distances (~4 core radius). Further, it showed that the effect of translation on velocity profiles is noticeable at and above an elevation of ~0.6 core radius, unlike those in studies based on the relative motion of the ground plane.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.2
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• pp.117-131
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• 1992

A studies on the pattern of sea water circulation was carried out by using drogue experiments, tidal current measurement and hydrographic data in Kamak Bay which has two channels. At the flood, the water inflowed from the northern narrow channel flows mostly to the southward then the westward because Daekyung-island located at the flow path, at the same time the water from the southern channel of bay directed strongly to the north with a spine centered at around Gunnaeri. And these waters converged at the area between eng-Island and Deakyung-Island in the bigining of the flow, and placed at less southern part than the area at the late. The water of the north west inner bay having concave bottom topography inflows to Najin inlet with a spin of anti-clockwise. At the ebb, those waters in the bay turn back to two channels respectively, but most of waters directed to the southern channel of the bay. The directions of residual current of two channels are the southward mainly, and the current of inner area are influenced by the prevailing wind. The north-west inner bay which has the weak tidal current less than 10 cm/sec shows a similar upwelling by off-shore wind in winter, and the stratification in summer, respectively.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.1
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• pp.11-17
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• 2023

In this study, the correlation analysis between total system error and environmental factor variables was performed to confirm the effect on the performance of the integrated navigation system by various environmental factors. To collect flight data of hybrid vertical take-off and landing UAVs, scenarios including various turning sections and straight sections such as left turn, right turn, turning rate, and path change angle were selected, and environmental data of wind direction, wind speed, temperature, air pressure, and humidity were collected in real time through weather station. As a result of the correlation analysis between the collected flight data and environmental data, it was concluded that the performance of the integrated navigation system by environmental factors within the collected data was not significant affected and was robust.

• Korean Journal of Applied Biomechanics
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• v.34 no.2
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• pp.63-70
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• 2024

Objective: This study aims to compare the basic aerodynamic characteristics of the official Qatar World Cup soccer ball with those of the official Korean soccer balls. Method: In this study, wind tunnel experiments were conducted to compare the fundamental aerodynamic properties of two commonly used domestic soccer balls, the Star and Nassau, with the Al Rihla, the official ball of the 2022 Qatar World Cup. Results: The findings revealed that the Nassau soccer ball exhibited changes in aerodynamic characteristics depending on its orientation, particularly at low speeds (below 15 m/s), while the Al Rihla showed variations in aerodynamic characteristics at medium to high speeds (15 m/s to 35 m/s) based on its orientation. Furthermore, the results of lift and side force variations indicated that the Star soccer ball exhibited larger changes compared to other soccer balls, suggesting that it may exhibit the most irregular flight path during strong shots (around 30 m/s or approximately 100 km/h). However, there were no differences in aerodynamics observed among the soccer balls in the medium-speed range (20~25 m/s). Conclusion: The comparison of aerodynamics between the Korean soccer balls and the most recently used World Cup official ball showed that, while the Korean balls exhibited slightly greater changes in lift and side forces compared to the World Cup ball, there were no significant differences in most of the aerodynamic characteristics.

• Analytical Science and Technology
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• v.8 no.4
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• pp.731-738
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• 1995

Toxic air pollutants are investigated in a petrochemical industrial park in Taiwan by using a movable open path FTIR. The results show the qualitative and quantitative analysis of emission gases from plants, and also provide the emission rate of different compounds. More than twenty compounds under usual operation are found from this industrial park. The concentration variation with time can be correlated exactly with wind direction. It means that by changing the measuring points, the source of emission can be unambiguously identified. An EPA proved PAL model is applied to estimate the emission rate of either a point or an area source. Local atmospheric stability is determined by releasing the $SF_6$ tracer. The origins of errors come mainly from the uncertainty of source's configuration and the variation of meteorological condition. Through the continuous measurement (half an hour base in this study) of OP-FTIR sensor, the maximum value of emission rate and the annual amount of emission can be derived. The emission rate of the measured toxic gases are derived by the model technique and the results show that the emission amount are in the order of ten to hundred tons per year.

• 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.

• 한국해양학회지
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• v.30 no.1
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• pp.57-63
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• 1995

Two-layered fluid with sloping bottom and top(${\beta}$-effect) in rigid cylinder is put on the rotating table. To drive the lower-layer motion in "the Sverdrup type" flow external fluid is pumped into the lower-layer. By introducing inlet-outlet system in the upper-layer, an analogy to the Tsushima Tsugaru, Soya of the East Sea has been tested. The position of the inlet-outlet system and the difference between the strength of inlet or outlet flow are changed to see the effects of the wind stress on the upper-layer. The northern part of inflow toward the outlet may be interpreted roughly as the position of the polar front in the East Sea. Experimental observations have revealed that the inflow flows along the western boundary before it separates into the interior and flows straight toward the outlet position. However, the wind effect is imposed upon the upper-layer, the western boundary flow branches into two parts of which one flows along the boundary and the other flows into the interior under the influence of negative wind stress curl, while southward western boundary flow seems to block the flow and deflect it to the interior. The changes in the position of inlet-outlet system produce more significant changes in flow pattern in that cyclonic flow in the north controls the northern extent of the polar front by deflecting the northward interior motion toward the west(outlet). Interface displacement which depends strongly on the velocity difference between two layers seems to play crucial role in terms of the path of upper-layer flow, particularity, the inflow.

• Journal of Environmental Science International
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• v.18 no.10
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• pp.1089-1101
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• 2009

In this paper, changes in the intensity (e.g., central pressure and maximum sustained wind speed) of Tropical Cyclone (TC) in summer in the regions located at $30^{\circ}N$ in East Asia from 1988 to 1991 were found. The intensity of TC from 1991 to 2007 was much higher than that of TC from 1965 to 1988. The reason for this was that the frequency of TCs passing China from 1991 to 2007 was much lower than that of TCs from 1965-1988 because a northeasterly wind caused by high-pressure circulation in East Asia got severer along the East Asian coast. Instead, TCs moved from the eastern region of the Tropical West Pacific to Korea and Japan mainly after passing the East China Sea due to the low-pressure circulation strengthened in the subtropical waters of East Asia. In addition, low Vertical Wind Shear (VWS) was created along the mid-latitude regions of East Asia and the main path of TCs from 1991 to 2007. Most of the regions in the Northwestern Pacific showed higher Sea Surface Temperature (SST) from 1991 to 2007, and had a good environment where TCs were able to maintain a higher intensity on the mid-latitude. In particular, a low sensible heat flux occurred due to high snow depth in East Asia in the spring of 1991 to 2007. Accordingly, the lower layer of East Asia showed high-pressure circulation, and the sea surrounding East Asia showed low-pressure circulation. Thus, the typical west-high, east-low pattern of winter atmospheric pressure was shown. The possibility of snowfall in East Asia in spring to be used as a factor for predicting the summer intensity of TC in the mid-latitude regions of East Asia was insinuated. The characteristics of TC in a low-latitude region were the same in Korea. The latest intensity of TCs got higher, and the landing location of TCs gradually changed from the west coast to the south coast.