• 한국측량학회지
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• 제13권2호
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• pp.291-298
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• 1995

본 연구에서는 중력장모델링에 있어서 단 파장의 효과인 지형보정량을 계산하고 지오이드의 효과에 미치는 DTM 데이타를 사용하여 계산하였다. 정밀한 지형보정량을 계산하기 위하여 $500\times{500m}$격자 간격의 DTM 데이타를 준비하여 매스프리즘 모델과 매스라인모델을 적용하였다. 적용결과 지형효과가 다소 크게 나타났으며, 이 결과는 정밀한 지오이드의 계산을 위하여는 지형효과가 고려되어야 한다는 것을 알 수 있었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.493-495
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• 2010

A three-dimensional flow simulation is performed to investigate the flow field in the ski resort on complex terrain. The present paper aims to study the wind effects of mountainous terrain on the gondola safety. Strong wind happens in the ski resort on the mountain by complex terrain and it causes the dangerous accident of gondola. A digital map around the ski resort area is used to model the actual complex terrain for a 3-D analysis domain. Wind direction and speed to be used as a boundary condition are taken from local meteorological reports. The numerical results show details of the velocity distribution around a ski resort. From the results, we can suggest the modification of the installation of gondola for the safety due to strong wind.

• 한국시뮬레이션학회논문지
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• 제4권1호
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• pp.113-119
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• 1995

In 3D computer graphics, fractal techniques have been applied to terrain models. Even though fractal models have become popular for recreating a wide variety of the shapes found in nature, a specific 3D terrain model such as Uleung Island could not be formulated by statistical fractals easily owing to the random effects. However, by locating the midpoints on the edges and the surface of a specific terrain such as Uleung Island, a similar shape of the terrain model can be simulated. This paper shows the way of simulating 3D Uleung Island terrain model by the statistical fractals wherein the subdivision algorithm is used.

• 한국대기환경학회지
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• 제19권6호
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• pp.757-772
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• 2003

We simulate the geographical effects on the onset time of sea breeze at Suyoung and Haeundae districts by using the LCM (Local Circulation Model). The following can be found out from the numerical simulation on Case I (real terrain) which considered the real geography of Busan metropolitan area. Especially, as a result of analyzing the land breeze path, it could be found along the coastline as it flows out through low land coastal area. To find out more about the effects of terrain and geography on the onset time of sea breeze, the results of numerical simulation of virtual geography are as follows. In Case II (flat terrain), to find out how the terrain slope affects the onset of sea breeze, flat land and the ocean was considered. As a result, convergence of nighttime air mass at a Suyoung area and nighttime strong wind speed phenomenon was not shown. In Case III (modified flat terrain), to find out the effects of the irregularity of coastline affecting the onset of sea breeze, numerical simulation was carried out by simplifying the complex coastline into segments of straight coastline. So land breeze system and changing process of sea breeze after sunrise at Suyoung and Haeundae was simulated almost in a similar manner. Through this we could find the effects of coastal irregularities on onset of sea breeze.

• Wind and Structures
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• 제19권5호
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• pp.541-563
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• 2014

This paper investigates the topographic effects on wind characteristics over hilly terrain, based on wind data recorded at a number of meteorological stations in or near complex terrain. The multiply data sources allow a more detailed investigation of the flow field than is normally possible. Vertical profiles of mean and turbulent wind components from a Sodar profiler were presented and then modeled as functions of height and wind speed. The correlations between longitudinal and vertical wind components were discussed. The phenomena of flow separation and generation of vortices were observed. The distance-dependence of the topographic effects on gust factors was revealed subsequently. Furthermore, the canyon effect was identified and discussed based on the observations of wind at a saddle point between two mountain peaks. This study aims to further understanding of the characteristics of surface wind over rugged terrain. The presented results are expected to be useful for structural design, prevention of pollutant dispersion, and validation of CFD (computational fluid dynamics) models or techniques over complex terrains.

• 한국정보과학회논문지:시스템및이론
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• 제28권10호
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• pp.499-506
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• 2001

Terrain Following이란 가상환경 내에서 지형의 표면을 이동할 때 지형의 모양에 따라 자연스럽게 지표 위를 이동할 수있게 하는것으로 가상환경내에서 중력의 효과를 실현해 주는 기술이다. Terrain Following 을 하기 위한 전통적인 접근 방법은 충돌감지(Collision Detection)알고리즘을 이용한 것이지만, 일 거인 충돌감지 알고리즘은 Terrain Following에 적용시키는 것은 계산에 드는 시간 비용이 너무 크다. 이러한 어려움 때문에 많은 가상환경 및 시뮬레이션 분야에서는 높이(z)가 일정한 지형을 사용함으로써 이러한 문제들을 회피하고 있는 실정이다. 이에 본 논문에서는 네비게이션시 발생하는 근접성(Locality)에 기반한 인접지역 탐색(Neighboring Area Search ) 기법을 사용하여 Terrain Following 알고리즘의 수행 시간을 단축시켜 Terrain Following 을 적용시키는데 발생하는 부하를 줄일 수 있는 알고리즘의제시를 목적으로 한다. 이는 Terrain Following 기법 자체의 속도 향상을 기대할수 있고 동시에 Terrain Following을 구현하고 유지하는데 드는 부하를 줄임으로써 가상현상을 구축하는데 사용되는 웨크스테이션을 Terrain Following 이외에 다른 부분의 구현에 이용할 수 있는 부가적 효과를 가져다 줄수 있다. 줄수 있다.

• 한국대기환경학회지
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• 제13권6호
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• pp.427-437
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• 1997

Complex terrain which is rather typical topographic character in Korea would greatly influence the dispersion of air pollutant. In this study, we investigated how the complex terrain in the vicinity of the coal-fired plant affects the air dispersion modeling results by using several US EPA models: SCREEN, CTSCREEN, ISCLT3, ISCST3, and RTDM. Screening analysis was followed by long-term analysis, and the plume movement over the terrain was precisely tracked for selected cases. Screening analysis revealed that the highest concentration of sulfur dioxide occurs at the downwind distance of 1.3 km under the unstable conditions with weak winds. However, this highest level of $SO_2$ could be raised by 4 times even in the presence of a hill of 170 m at a distance of 2 to 3 km. Seasonal and annual average concentrations predicted with the ISCLT3, ISCST3, and RTDM models showed a rapid incrase of $SO_2$ levels in front of the high mountains which are located more than 15 km away fromt the source. The highest concentrations predicted with ISCST3 were significantly higher than those with ISCLT3 and RTDM mainly because ISCST3 chooses simple-terrain model calculations for receptors between stack height and plume height. Although the highest levels under the stable conditions were usually found in the areas beyond 15 km or more, their absolute values were not so high due to enough dispersion effects between the source and the receptors.

• 지구물리와물리탐사
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• 제6권4호
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• pp.165-170
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• 2003

최근 전기비저항탐사는 산악과 같은 지형의 기복이 심한 지역에서도 널리 수행되고 있다. 그러나 이러한 지형의 기복은 전기비저항 탐사자료의 왜곡을 유발하며, 잘못된 해석의 원인이 될 수도 있다. 본 논문에서는 전기비저항탐사에서의 지형효과를 유한요소법에 의한 수치모델링과 축소모형의 두 종류의 모형실험을 통하여 분석하였다. 한편 축소모형실험을 연못에서 수행함으로써, 실내 수조 모형실험에서 문제가 될 수 있는 가장자리 효과를 피할 수 있었다. 다양한 경사를 갖는 능선과 계곡 지형 모형에 대하여 모형실험을 수행하였으며, 두 종류의 실험결과가 실험한 모든 지형모형에 대하여 서로 잘 부합됨을 확인하였다. 분석결과, 계곡모델은 계곡의 중심부에 낮은 겉보기비저항대가 분포하고 그 좌우에 높은 겉보기비저항대가 나타나는 양상을 보이며, 능선모델은 그 반대의 양상을 보인다. 또한 능선 및 계곡 모두 그 경사가 심할 경우에는 음의 겉보기비저항을 나타낼 수도 있음을 확인하였다. 따라서 전기비저항 탐사 자료의 해석시 지형효과를 꼭 고려해야 할 것으로 판단된다.

• 한국지구과학회지
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• 제25권8호
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• pp.784-798
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• 2004

복잡한 산악지형과 숲이 있는 나로 우주센터의 미규모 바람장을 MUKLIMO를 사용하여 모의하였다. 지형과 나무가 있을 때 모델의 민감도를 실험하기 위하여 각종 초기조건하에 수치모의를 수행하였다. 실험결과 나무는 평지 위에 서는 큰 영향을 미치나 언덕지형에서는 큰 영향을 미치지 못함을 알았다. 이러한 실험결과를 이용하여 나로 우주센터의 10m 상공에서의 미규모 바람장과 또, 발사장의 건설전후의 바람장도 모의하였다. 본 연구결과 MUKLIMO는 복접한 지형에서도 바람장의 수치모의가 가능하며 매우 유용함을 알았고 우주센터에서의 바람의 특성이 규명되었다.

• Structural Engineering and Mechanics
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• 제45권1호
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• pp.1-18
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• 2013

The typhoon wind characteristics designing for buildings or bridges located in complex terrain and typhoon prone region normally cannot be achieved by the very often few field measurement data, or by physical simulation in wind tunnel. This study proposes a numerical simulation procedure for predicting directional typhoon design wind speeds and profiles for sites over complex terrain by integrating typhoon wind field model, Monte Carlo simulation technique, CFD simulation and artificial neural networks (ANN). The site of Stonecutters Bridge in Hong Kong is chosen as a case study to examine the feasibility of the proposed numerical simulation procedure. Directional typhoon wind fields on the upstream of complex terrain are first generated by using typhoon wind field model together with Monte Carlo simulation method. Then, ANN for predicting directional typhoon wind field at the site are trained using representative directional typhoon wind fields for upstream and these at the site obtained from CFD simulation. Finally, based on the trained ANN model, thousands of directional typhoon wind fields for the site can be generated, and the directional design wind speeds by using extreme wind speed analysis and the directional averaged mean wind profiles can be produced for the site. The case study demonstrated that the proposed procedure is feasible and applicable, and that the effects of complex terrain on design typhoon wind speeds and wind profiles are significant.