• Atmosphere
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• v.19 no.4
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• pp.345-370
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• 2009

Numerical experiments using the Weather Research and Forecasting (WRF) model were done to identify the role of the mountain ranges in the northern part of the Peninsula (referred as "the northern mountain complex"), in the occurrence of two heavy snowfall events over the Yeongdong region on 7-8 December 2002 and 20-21 January 2008. To this end, control simulations with the topography of the northern mountain complex and other simulations without the topography of the mountain complex were performed. It was revealed that the amount of snowfall over the Yeongdong region from the control simulation much more exceeded that of the simulation without the topography of the mountain complex. This increase of the snowfall amount over the Yeongdong region can be explained as follows: As the upstream flow approached the northern mountain complex, it deflected around the northern mountain complex due to the blocking effect of the mountains with a low Froude number less than ~0.16. This lead to the strengthening of northeasterly over the East Sea and over the Yeongdong region. The strong northeasterly is accompanied with much more snowfall over the Yeongdong region by intensifying air-mass modification over the sea and the orographic effect of the Taeback mountains. Thus, it was concluded that the topography of the northern mountain complex is one of the main factors in determining the distribution and amount of precipitation in the Yeongdong region when there is an expansion of the Siberian High toward the East Sea.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.6
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• pp.649-661
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• 2008

The impact of the detailed surface data on regional meteorological fields in complex coastal area is studied using RAMS. Resolutions of topography and land use data are very important to numerical modeling, because high resolution data can reflect correct terrain height and detail characteristics of the surface. Especially, in complex coastal region such as Gwangyang area, southern area in Korean Peninsula, high resolution topography and land use data are indispensable for accurate modeling results. This study investigated the effect of resolutions of terrain data using SRTM with 3 second resolution topography and KLU with 1 second resolution land use data. Case HR was the experiment using high resolution data, whereas Case LR used low resolution data. In Case HR, computed surface temperature was higher than Case LR along the coastline and wind speed was $1{\sim}2m/s$ weaker than Case LR. Time series of temperature and wind speed indicated great agreement with the observation data. Moreover, Case HR indicated outstanding results on statistical analysis such as regression, root mean square error, index of agreement.

• Journal of the Korean Solar Energy Society
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• v.29 no.6
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• pp.62-68
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• 2009

There has been a continuous increase in the utilization and utility value of renewable energy such as wind power generation in modem society. Wind condition is the absolute variable to the energy volume in the case of a wind power generation system. For this reason, wind power generators have already been installed in areas where wind velocity is high and the possibility of danger is very low. In other words, instability is likely if the wind velocity in an area is high and where a wind power generation system can be built. On the contrary, low wind velocity is possible in an area with high stability. Therefore, the design and manufacture of a wind power generation system should be carried out in a more complicated topography in order to secure a bigger market. This study examines and suggest how topography affects wind shear by analyzing the measured data in order to predict wind power generation more reliably.

• Wind and Structures
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• v.18 no.5
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• pp.549-566
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• 2014

In spite of progress in the numerical simulation of typhoon wind field in atmospheric boundary layer (ABL), using typhoon wind field model in conjunction with Monte Carlo simulation method can only accurately evaluate typhoon wind field over a general terrain. This method is not enough for a reliable evaluation of typhoon wind field over the actual complex terrain with surface roughness and topography variations. To predict typhoon wind field over the actual complex terrain in ABL, a hybrid numerical simulation method combined typhoon simulation used the typhoon wind field model proposed by Meng et al. (1995) and CFD simulation in which the Reynolds averaged Navier-Stokes (RANS) equations and k-${\varepsilon}$ turbulence model are used. Typhoon wind filed during typhoon Dujuan and Imbudo are simulated using the hybrid numerical simulation method, and compared with the results predicted by the typhoon wind field model and the wind field measurement data collected by Fugro Geotechnical Services (FGS) in Hong Kong at the bridge site from the field monitoring system of wind turbulence parameters (FMS-WTP) to validate the feasibility and accuracy of the hybrid numerical simulation method. The comparison demonstrates that the hybrid numerical simulation method gives more accurate prediction to typhoon wind speed and direction, because the effect of topography is taken into account in the hybrid numerical simulation method.

• Journal of architectural history
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• v.19 no.5
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• pp.49-63
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• 2010

With the effect that the Yipsu-ryong(入首龍) of Ju-san(主山) influenced on the layout in the view of geomantic topography(形勢), how Ahn-san(案山) affected the layout plan of the Korean academics of classical learning(書院) is researched. And how the "Jirisinbeob(地理新法)" which had been written by Ho-sun-sin(胡舜申) was applied to the Korean academics of classical learning in the view of Li and Ch'i(理氣) is studied. In Fengshui, the method to pick out a site and to confirm the direction for building construction was divided into two, one of them was 'the geomantic topography', which included 'Ju-san following type(主山順應形)', 'Ahn-san stressing type(案山重視形)' and 'Ju-san & Ahn-san complex type(主 案山混合形)'. And the other is the 'Rule of direction(向法)'. The Korean academics of classical learning was applied by the geomantic topography of Fengshui for its layout and direction, regardless of political, regional and period factors. So when the Sa-rim(士林) needed to set direction for the Korean academics of classical learning, the ground that was appropriate to the geomantic topography of Fengshui was selected. Therefore, the Sa-rim who was abused in Neo-Confucianism had a mind of stressing geomantic topography of Fengshui and they applied it positively for building construction.

• Wind and Structures
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• v.13 no.5
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• pp.433-449
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• 2010

Wind tunnel model tests were conducted for a residential apartment block located within the complex terrain of The Hong Kong University of Science and Technology (HKUST). The test building is typical of medium-rise residential buildings in Hong Kong. The model study was conducted using modelling techniques and assumptions that are commonly used to predict design wind loads and pressures for buildings sited in regions of significant topography. Results for the building model with and without the surrounding topography were compared to investigate the effects of far-field and near-field topography on wind characteristics at the test building site and wind-induced external pressure coefficients at key locations on the building facade. The study also compared the wind tunnel test results to topographic multipliers and external pressure coefficients determined from nine international design standards. Differences between the external pressure coefficients stipulated in the various standards will be exacerbated when they are combined with the respective topographic multipliers.

• Journal of Environmental Science International
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• v.4 no.2
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• pp.245-251
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• 1995

Generally, It is Introduced to well-known other models without considering tidal current of the field. The paper presents field measurements and numerical model solving velocity field of Cheonsu Bay by two-dimensional tidal model. It was proved that this scheme is easy to handle complex topography. Computed results is represented characteristics of tidal current for Cheonsu Bay. The results of the study can be summarized as follows ; 1. Tide form number has 0.21 value. Tidal range estimated 630.3 cm on spring, 454.1 cm on mean and 277.9 cm on neap, respectively 2. Tidal current has semi-diurnal form. Distance of traveling observed 16.6 km on flood and 15.5 km on ebb. 3. Tidal velocity showed reversing current. It was found that tidal velocity above 100 cm/sec is about 20 %. 4. Computed results are in good agreement with the observed data. Applying the algorithm to Cheonsu Bay, velocity fields and dry bank phenomena are simulated well in spite of complex topography. 5. An advanced study on the effects of open boundary conditions should be continuously performed.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.5
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• pp.411-420
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• 1998

To estimate the dispersion coefficients in a coastal area with complex topography, several schemes using empirical equations expressed with and in lateral and vertical directions, respectively have been examined. Estimation results using these equations and meteorological data obtained from SODAR system were compared' with previously measured dispersion coefficients in other coastal areas. Validations of estimation results have been performed by comparing the measured concentrations with predicted ones empolying in Boryung coastal area. Important conclusions were drawn as follows; (1) Variations of lateral and vertical wind direction revealed different height dependency in upper and lower mixed boundary layer. (2) Because of turbulent constraint effect by large water body in a coastal region, the lateral and the vertical dispersion coefficients were smaller than those of P-G system. (3) As a result of examining the performance measure of these schemes through checking of coincidence between measured and predicted concentrations, vertical dispersion coefficients were smaller than those of P-G system, and the Cramer scheme was found to be more appropriate rather than others in the coastal area surrounding Boryung power plant.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.3
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• pp.119-127
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• 1993

Recently, ADI scheme has been a most common tool for solving shallow water equation numerically. But ADI models of tidal flow is likely to cause so called ADI effect in such a region of the Yellow Sea which shows complex topography and has submarine canyons especially. To overcome this, a finite difference algorithm is developed which adopts fully implicit method and preconditioned conjugate gradient squared method. Applying the algorithm including simulation of intertidal zone to Sae-Man-Keum. velocity fields and flooding/drying phenomena are simulated well in spite of complex topography.

• Atmosphere
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• v.20 no.3
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• pp.343-353
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• 2010

A regional wind network with complex surface conditions must be designed with sufficient space and time resolution to resolve the local circulations. In this study, the spatial variations of the wind field observed in the Seoul and Jeju regional networks were evaluated in terms of annual, seasons, and months to assess the spatial homogeneity of wind fields within the regional networks. The coherency of the wind field as a function of separation distance between stations indicated that significant coherency was sometimes not captured by the network, as inferred by low correlations between adjacent stations. A meso-velocity scale was defined in terms of the spatial variability of the wind within the network. This problem is predictably most significant with weak winds, dull prevailing wind, clear skies and significant topography. The relatively small correlations between stations imply that the wind at a given point cannot be estimated by interpolating winds from the nearest stations. For the Seoul and Jeju regional network, the meso-velocity scale has typically a same order of magnitude as the speed of the network averaged wind, revealing the large spatial variability of the Jeju network station imply topography and weather. Significant scatter in the relationship between spatial variability of the wind field and the wind speed is thought to be related to thermally-generated flows. The magnitude of the mesovelocity scale was significantly different along separation distance between stations, wind speed, intensity of prevailing wind, clear and cloudy conditions, topography. Resultant wind vectors indicate much different flow patterns along condition of contributing factors. As a result, the careful considerations on contributing factors such as prevailing wind in season, weather, and complex surface conditions with topography and land/sea contrast are required to assess the spatial variations of wind field on a regional network. The results in the spatial variation from the mesovelocity scale are useful to represent the characteristics of regional wind speed including lower surface conditions over the grid scale of large scale atmospheric model.