• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 추계학술대회
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• pp.533-534
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• 2013

컴퓨터 게임에서 눈 덥힌 산이나 계곡 등을 표현하기 위해 지형 모델을 사용하며, 이러한 지형모델은 게임 속에서 캐릭터가 생활하는 공간으로 게임에서 없어서는 안 될 중요한 요소이다. 지형모델의 사실적인 묘사는 게임의 몰입도를 좌우하기 때문에, 현재는 많은 지형 모델 툴을 통하여 만들고 있다. 본 논문에서는 지형 모델을 툴을 이용하지 않고, 3D MAX를 이용하여 누구나 쉽게 제작할 수 있는 방법에 대해 설명한다. 3D MAX는 그래픽 디자이너들에게 많이 쓰이고 있으며, 3D 그래픽 소프트웨어로 유지보수가 쉽다는 장점이 있다. 본 논문에서는 3D MAX를 이용하여 지형 모델을 만들고, 이를 DirectX 환경에서 사용하는 방법에 대해 설명한다.

• Wind and Structures
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• 제28권4호
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• pp.239-253
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• 2019

Accurate numericalsimulation of wind field over complex terrain is an important prerequisite for wind resource assessment. In this study, numerical simulation of wind field over complex terrain was further carried out by taking the complex terrain around Siu Ho Wan station in Hong Kong as an example. By artificially expanding the original digital model data, Gambit and ICEM CFD software were used to create high-precision complex terrain model with high-quality meshing. The equilibrium atmospheric boundary layer simulation based on RANS turbulence model was carried out in a flat terrain domain, and the approximate inflow boundary conditions for the wind field simulation over complex terrain were established. Based on this, numerical simulations of wind field over complex terrain under different inflow wind directions were carried out. The numerical results were compared with the wind tunnel test and field measurement data for land and sea fetches. The results show that the numerical results are in good agreement with the wind tunnel data and the field measurement data which can verify the accuracy and reliability of the numerical simulation. The near ground wind field over complex terrain is complex and affected obviously by the terrain, and the wind field characteristics should be fully understood by numerical simulation when carrying out engineering application on it.

• 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.

• 한국지리정보학회지
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• 제9권1호
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• pp.127-136
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• 2006

수치지형모형을 시각적으로 분석하는데 있어 음영기복을 사용하고 있지만 지형의 음영 표현만을 생각하는 경우가 있어 정확한 그림자 범위를 확인하지 않고 있다. 본 연구는 GIS의 지형 표현에 사용되는 음영기복 기능을 렌더링과 비교하여 지형의 그림자 특성을 파악함으로써 각각 나타나는 수치지형모형상의 표현 차이를 분석하였다. 도로가 있는 지형으로 실험 대상지역을 선정하여 불규칙삼각망의 수치지형모형을 생성한 후 09시와 15시의 시간대별 태양의 방위각 및 고도에 따른 음영기복과 렌더링 기법을 적용하였다. 그 결과 음영기복은 태양의 광선을 받는 지형지물의 뒷부분만 어두운 상태로 나타났고, 렌더링을 통하여 투영된 그림자가 생성됨을 알 수 있었다. 이 상호 비교를 통해 음영기복을 이해할 수 있는 자료로 제시할 수 있으며, 렌더링 기법은 지형지물의 일조 분석 등에 효과적으로 사용될 수 있을 것으로 기대된다.

• 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.

• Wind and Structures
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• 제13권3호
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• pp.275-292
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• 2010

Wind tunnel experiments were conducted to investigate the wind characteristics in the mountainous valley terrain with 4 simplified valley models and a 1:500 scale model of an existing valley terrain in the simulated atmospheric neutral boundary layer model. Measurements were focused on the mean wind flow and longitudinal turbulence intensity. The relationship between hillside slopes and the velocity speed-up effect were studied. By comparing the preliminary results obtained from the simplified valley model tests and the existing terrain model test, some fundamental information was obtained. The measured results indicate that it is inappropriate to describe the mean wind velocity profiles by a power law using the same roughness exponent along the span wise direction in the mountainous valley terrain. The speed-up effect and the significant change in wind direction of the mean flow were observed, which provide the information necessary for determining the design wind speed such as for a long-span bridge across the valley. The longitudinal turbulence intensity near the ground level is reduced due to the speed-up effect of the valley terrain. However, the local topographic features of a more complicated valley terrain may cause significant perturbation to the general wind field characteristics in the valley.

• 제어로봇시스템학회논문지
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• 제18권10호
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• pp.940-946
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• 2012

This paper proposes a method to predict maximum traction for unmanned robots on rough terrain in order to improve traversability. For a traction prediction, we use a friction-slip model based on modified Brixius model derived empirically in terramechanics which is a function of mobility number $B_n$ and slip ratio S. A friction-slip model includes characteristics of various rough terrains where robots are operated such as soil, sandy soil and grass-covered soil. Using a friction-slip model, we build a prediction model for terrain parameters on which we can know maximum static friction and optimal slip with respect to mobility number $B_n$. In this paper, Mobility number $B_n$ is estimated by modified Willoughby Sinkage model which is a function of sinkage z and slip ratio S. Therefore, if sinkage z and slip ratio are measured once by sensors such as a laser sensor and a velocity sensor, then mobility number $B_n$ is estimated and maximum traction is predicted through a prediction model for terrain parameters. Estimation results for maximum traction are shown on simulation using MATLAB. Prediction Performance for maximum traction of various terrains is evaluated as high accuracy by analyzing estimation errors.

• 한국측량학회지
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• 제11권2호
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• pp.17-26
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• 1993

최근 국토의 효율적인 개발을 목적으로 신설도로의 건설이 급증하고 있다. 그러나 우리나라는 경제 개발사업이 시작되면서 국토개발이 활발히 추진됨에 따라 국토의 자연활경에 많은 손상을 가져 왔던 것도 부인할 수 없는 사실이다. 이런 관점에서 본 연구는 도로개발사업시 효율적인 최적노선을 창출하기 위해 연구대상지를 선정하여 종래 방법과 수치지형모형방법으로 구분하고 최적노선 선정시 현황지형, 토공량 변화에 따른 예측지형 및 주변경관해석의 한 방법을 제시하고자 하였다. 연구결과 수치지형모형으로 노선계획시 토공량변화에 따른 예측지형 및 경관도를 작성할 경우 종래 조감도 및 투시도 방법보다 입체적이고 시각적이며, 대상지의 다양한 지형인자를 삽입하면 최적 노선선정시 토공량산정, 종·횡단면도 작성, 경관도, 조경도 등 모든 노선계획의 수치화가 가능하므로 도로 건설사업시 그 활용도가 기대된다.

• Wind and Structures
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• 제20권1호
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• pp.15-36
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• 2015

Characterization of wind flows over a complex terrain, especially mountain-gorge terrain (referred to as the very complex terrain with rolling mountains and deep narrow gorges), is an important issue for design and operation of long-span bridges constructed in this area. In both wind tunnel testing and numerical simulation, a transition section is often used to connect the wind tunnel floor or computational domain bottom and the boundary top of the terrain model in order to generate a smooth flow transition over the edge of the terrain model. Although the transition section plays an important role in simulation of wind field over complex terrain, an appropriate shape needs investigation. In this study, two principles for selecting an appropriate shape of boundary transition section were proposed, and a theoretical curve serving for the mountain-gorge terrain model was derived based on potential flow theory around a circular cylinder. Then a two-dimensional (2-D) simulation was used to compare the flow transition performance between the proposed curved transition section and the traditional ramp transition section in a wind tunnel. Furthermore, the wind velocity field induced by the curved transition section with an equivalent slope of $30^{\circ}$ was investigated in detail, and a parameter called the 'velocity stability factor' was defined; an analytical model for predicting the velocity stability factor was also proposed. The results show that the proposed curved transition section has a better flow transition performance compared with the traditional ramp transition section. The proposed analytical model can also adequately predict the velocity stability factor of the wind field.

• 대기
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• 제18권4호
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• pp.387-395
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• 2008

The impact of horizontal resolution on a regional climate model was investigated by simulating precipitation over the Korean Peninsula. As a regional climate model, the SNURCM(Seoul National University Regional Climate Model) has 21 sigma layers and includes the NCAR CLM(National Center for Atmospheric Research Community Land Model) for land-surface model, the Grell scheme for cumulus convection, the Simple Ice scheme for explicit moisture, and the MRF(Medium-Range Forecast) scheme for PBL(Planetary Boundary Layer) processing. The SNURCM was performed with 20 km resolution for Korea and 60 km resolution for East Asia during a 20-year period (1980-1999). Although the SNURCM systematically underestimated precipitation over the Korean Peninsula, the increase of model resolution simulated more precipitation in the southern region of the Korean Peninsula, and a more accurate distribution of precipitation by reflecting the effect of topography. The increase of precipitation was produced by more detailed terrain data which has a 10 minute terrain in the 20 km resolution model compared to the 30 minute terrain in the 60 km resolution model. The increase in model resolution and more detailed terrain data played an important role in generating more precipitation over the Korean Peninsula. While the high resolution model with the same terrain data resulted in increasing of precipitation over the Korean Peninsula including the adjoining sea, the difference of the terrain data resolution only influenced the precipitation distribution of the mountainous area by increasing the amount of non-convective rain. In conclusion, the regional climate model (SNURCM) with higher resolution simulated more precipitation over the Korean Peninsula by reducing the systematic underestimation of precipitation over the Korean Peninsula.