• Wind and Structures
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• 제31권2호
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• pp.165-183
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• 2020

The first step of performance-based design for transmission lines is the determination of wind fields as well as wind loads, which are largely depending on local wind climate and the surrounding terrain. Wind fields in a mountainous area are very different with that in a flat terrain. This paper firstly investigated both mean and fluctuating wind characteristics of a typical mountainous wind field by wind tunnel tests and computational fluid dynamics (CFD). The speedup effects of mean wind and specific turbulence properties, i.e., turbulence intensity, power spectral density (PSD) and coherence function, are highlighted. Then a hybrid simulation framework for generating three dimensional (3D) wind velocity field in the mountainous area was proposed by combining the CFD and proper orthogonal decomposition (POD) method given the properties of the target turbulence field. Finally, a practical 220 kV transmission line was employed to demonstrate the effectiveness of the proposed wind field generation framework and its role in the performance-based design. It was found that the terrain-induce turbulence effects dominate the performance-based structural design of transmission lines running through the mountainous area.

• Wind and Structures
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• 제30권6호
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• pp.649-662
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• 2020

The existence of a dam has potential effects on the surrounding wind environment especially when it is located in mountainous areas. In this situation, the long-span bridge over the reservoir can easily be exposed to non-uniform incoming flows, affecting its wind-resistance performance. This paper presents a study on the aerostatic stability of such a bridge. Wind tunnel tests were first carried out to investigate the wind environment above a mountainous reservoir. The results show that the angle of attack and the wind speed along the bridge axis show obvious non-uniform characteristics, which is related to the inflow direction. When winds come from the south where the river is winding, the angle of attack varies along the span direction significantly. The finite element model for the bridge was established using ANSYS software, and effects of non-uniform wind loads on the aerostatic stability were computed. Non-uniform angle of attack and wind speed are unfavorable to the aerostatic stability of the bridge, especially the former. When the combined action of non-uniform angle of attack and wind speed is considered, the critical wind speed of aerostatic instability is further reduced. Moreover, the aerostatic stability of the bridge is closely related to the dam height.

• 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.

• Wind and Structures
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• 제7권5호
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• pp.345-357
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• 2004

In the 1990s, four strong typhoons hit the Kyushu area of Japan and inflicted severe damage on power transmission facilities, houses, and so on. Maximum gust speeds exceeding 60 m/s were recorded in central Kyushu. Although the wind speeds were very high, the gust factors were over 2.0. No meteorological stations are located in mountainous areas, creating a deficiency of meteorological station data in the area where the towers were damaged. Since 1995 the authors have operated a network for wind measurement, NeWMeK, that measures wind speed and direction, covering these mountainous areas, segmenting the Kyushu area into high density arrays. Maximum gusts exceeding 70 m/s were measured at several NeWMeK sites when Typhoon Bart (1999) approached. The gust factors varied widely in southerly winds. The mean wind speeds increased due to effects of the local terrain, thus further increasing gust speeds.

• 한국환경과학회지
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• 제6권4호
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• pp.359-367
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• 1997

The Characteristics of atmospheric flow and dispersion of air pollutants in the mountainous coastal area were studied using three-dimensional model by the combination of land/sea breezes and transport. It was then applied to Pusan city. As the urban area considered In this study is located in a mountainous coastal area, the atmospheric flow is strongly affected by the land/sea breezes and mountain/valley winds. The typical effects of land/sea breezes on the dispersion and the characteristics of pollutants movement in the region were analysed. The model has been proved to be an useful tool to prodict real time air pollutants transport as shown by the results of application studies In Pusan, Korea which Is an urbanized coastal area with mountainous topography. It was found that the pollutants are differently transported and concentrated as going Inland by the Influence of the sea breeze with topographic changes. By comparing the pollutants concentrations of the stimulated results with those of the observational results, It is shown that stimulated results in this study are in qualitative agreement with observational ones.

• 한국산림과학회지
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• 제97권3호
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• pp.340-347
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• 2008

본 연구는 산촌지역축제인 주왕산수달래축제를 대상으로 축제 품질서비스와 방문객만족도, 만족도와 방문객 충성도 및 축제효과 간의 개념적 구조관계를 분석하기 위하여 공변량구조모형분석을 실시하였다. 현지 설문조사는 2008년 주왕산수달래축제 방문객 445명에 대하여 조사가 이루어졌다. 분석결과, 축제 서비스품질을 구성하는 하위차원인 축제경험, 부대시설, 서비스 요인 모두 방문객만족에 영향을 주는 것으로 나타났으며, 방문객만족은 충성도와 축제효과에 영향을 주는 것으로 분석되었다. 축제 품질서비스 가운데 하위개념인 서비스 요인은 방문객만족도에 가장 큰 영향을 미치는 것으로 나타났다. 이러한 결과는 축제의 성공적 개최나 산촌지역주민에게 긍정적 효과를 주기 위해서는 축제진행요원의 환대(친절)나 행사안내와 같은 정보제공에 우선순위를 두어 집중적으로 관리함으로써 방문객만족을 향상시킬 수 있다는 이론적 근거를 제시하고 있다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.537-540
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• 2004

Space-borne multi-sensor data could provide fire scar and bum severity mapping. This paper will present detail mapping of burnt areas in Cheongyange Yesan of Korea with ETM+ image. Burn severity map based on ETM+ image was found to be affected by strong topographic illumination effects in mountainous forest area. Topographic effect is a factor which causes errors in classification of high spatial resolution image like IKONOS image. Minnaert constants J( in each band of ETM+ image is derived for reduction of mountainous terrain effects. Finally, this paper computes quantitative analysis of forest fire damage by each forest types.

• Wind and Structures
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• 제32권5호
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• pp.423-437
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• 2021

Aerodynamic measures have been widely used for improving the flutter stability of long-span bridges, and this paper focuses their windproof ability to improve the wind environment for vehicles. The whole wind environment around a long-span bridge located in high altitude mountainous areas is first studied. The local wind environment above the deck is then focused by two perspectives. One is the windproof effects of aerodynamic measures, and the other is whether the bridge with aerodynamic measures meets the requirement of flutter stability after installing extra wind barriers in the future. Furthermore, the effects of different wind barriers are analyzed. Results show that aerodynamic measures exert potential effects on the local wind environment, as the vertical stabilizer obviously reduces wind velocities behind it while the closed central slot has limited effects. The suggested aerodynamic measures have the ability to offset the adverse effect of the wind barrier on the flutter stability of the bridge. Behind the wind barrier, wind velocities decrease in general, but in some places incoming flow has to pass through the deck with higher velocities due to the increase in blockage ratio. Further comparison shows that the wind barrier with four bars is optimal.

• 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.

• 한국습지학회지
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• 제16권1호
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• pp.113-124
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• 2014

강우량은 관측소의 설치고도에 따라 관측량의 편차가 심하며, 이로 인해 도시지역과 산지지역의 강우발생 특성이 다르다. 산지효과로 인해 고도가 높아질수록 강우 관측시 불확실성이 커지는 것을 감안하면 산지지역에서의 강우관측소 밀도는 커야한다. 이러한 관측소의 고도특성이 반영된 관측망 평가는 산지효과를 반영하기 위한 것으로 산악지역에서 발생하는 돌발홍수의 효과적인 예측 및 레이더 자료의 보정에 있어 중요한 과정이 된다. 이에 본 연구에서는 강우관측소의 설치고 도를 고려한 강우관측망의 평가방법론을 제안하였다. 강우관측소의 고도별 설치밀도 파악을 위해 고정간격의 고도를 이용하는 등고도비별 설치밀도 산정방법과 유역의 면적비를 이용하는 등면적비별 설치밀도 산정방법을 적용하였다. 그 결과 등면적비를 이용하는 경우가 고도별 강우관측망의 평가에 보다 유리함을 확인하였다. 아울러 타유역과의 비교를 위해 등면적별 관측소 설치밀도의 변동계수를 이용하여 고도별 분포를 정량화 하였다. 이는 강우관측소의 설치고도분포의 균등함을 평가하는 정량적 지표가 되며, 제시된 방법론을 5대강 유역에 적용하였다. 그 결과, 설치밀도의 변동계수가 작은 유역에서는 고도별 강우설치밀도가 일정함으로 인해 보다 균등한 분포를, 반면 변동계수가 큰 유역에서는 상대적으로 고도별 설치밀도가 불균등함을 확인하였다.