• Journal of Mechanical Science and Technology
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• v.20 no.1
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• pp.29-41
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• 2006

Nowadays, with the advancement of computers, computer simulation linked with VR (Virtual Reality) technology has become a useful method for designing the automotive driving system. In this paper, the VR simulation system was developed to investigate the driving performances of the ASV (Advanced Safety Vehicle) equipped with an ACC (Adaptive Cruise Control) system. For this purpose, VR environment which generates visual and sound information of the vehicle, road, facilities, and terrain was organized for the realistic driving situation. Mathematical models of vehicle dynamic analysis, which includes the ACC algorithm, have been constructed for computer simulation. The ACC algorithm modulates the throttle and the brake functions of vehicles to regulate their speeds so that the vehicles can keep proper spacing. Also, the real-time simulation algorithm synchronizes vehicle dynamics simulation with VR rendering. With the developed VR simulation system, several scenarios are applied to evaluate the adaptive cruise controlled vehicle for various driving situations.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.402-409
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• 2008

Wind loads and environments in realistic situations surrounded by neighboring buildings may be considerably different from those in idealized or simplified situations such as codes and standards. Interference effects of change in wind passage of a building group on wind loads and wind environments are reviewed. Wind-induced interference effects depend mainly on the building geometry and arrangement of these structures, their orientation and upstream terrain conditions. The most important factor among them may be the arrangement of building structures which can change the wind direction directly. Interference effects regarding wind loads are discussed with examples of window damages by typhoon and of pressure measurements in the boundary layer wind tunnel. Wind environment problems are also discussed, specially underlined on pedestrian comfort and safety. Various evaluation techniques or standards of wind environment are introduced. The change of wind velocity between the panel-type apartment buildings is examined, depending on the distance each other.

• Journal of Korean Society of Rural Planning
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• v.19 no.4
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• pp.177-189
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• 2013

3D modeling and rendering technologies are getting more attention from landscape planners and architects because the virtual reality based on 3D graphic technology could give more realistic experience to landscape simulation users and boost promotional effects. The 3D landscape simulation, however, not only requires a lot of cost and time in production, but also demands efforts to distribute to consumers due to various computing environment of them. The purpose of this study is to suggest a process for developing an interactive 3D landscape simulator with low-cost, which can support multi-platform functionality in high quality through reviewing related current software and web services. We select GIMP for 2D image texturing, SketchUpfor 3D modeling, Unity for real-time rendering, and Google Earth for terrain modeling considering price and workability and apply the developed process for Windows, Web, and Android versions to test the applicability for Sangji-ri, Gosam-myeon, Gyeonggi-do, Korea.

• Korean Journal of Computational Design and Engineering
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• v.18 no.3
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• pp.189-199
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• 2013

The need for reusing synthetic environment data that are employed in the field of modeling and simulation has recently been rising. SEDRIS (Synthetic Environment Data Representation & Interchange Specification) is a standard to exchange synthetic environment data, and is the specification utilized in various military simulations of the Pentagon for representing and exchanging 3D data. SEDRIS represents environmental areas based on a data model; it can represent wind speed, wind directions, weather changes, the information of buildings, as well as terrain data. In some situations, however, the synthetic environment data stored in SEDRIS format should be converted to various visualization formats. First, because SEDRIS is a form of a super-set, it is necessary to verify whether large scale SEDRIS files are stored successfully through visualization. Second, the synthetic environment data should be visualized in some visualization programs for the simulation results to provide an immersive and realistic sense. In this study, we have developed converters for converting SEDRIS data to various visualization formats and visualized the converted results.

• Korean Journal of Remote Sensing
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• v.8 no.2
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• pp.131-145
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• 1992

A low cost personal computer and image processing S/W were empolyed to derive Digtal Elevation Model(DEM) of tidal flat from multitemporal LANDSAT TM images, and to create three-dimensional(3D) perspective views of the tidel flat on Komso bay in west coasts of Korea. The method for generation of Digital Elevation Model(DEM) in tidal flat was considered by overlapping techniques of multitemporal LANDSAT TM images and interpolations. The boundary maps of tidal flat extracted from multitemporal images with different water high were digitally combined in x, y, z space with tide in formation and used as an inputcontour data to obtain an elevation model by interpolation using spline function. Elevation errors of less than $\pm$0.1m were achived using overlapping techniques and a spline interpolation approach, respectively. The derived DEM allows for the generation of a perspective grid and drape on the satellite image values to create a realistic terrain visualization model so that the tidal flat may be viewed from and desired direction. As the result of this study, we obtained elevation model of tidal flats which contribute to characterize of topography and monitoring of morphological evolution of tidal flats. Moreover, the modal generated here can be used for simulation of innudation according to tide and support other studies as a supplementary data set.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.9
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• pp.3120-3137
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• 2021

Small-sized IoT wireless sensing devices can be deployed with small aircraft such as drones, and the deployment of mobile IoT devices can be relocated to suit data collection with efficient relocation algorithms. However, the terrain may not be able to predict its shape. Mobile IoT devices suitable for these terrains are hopping devices that can move with jumps. So far, most hopping sensor relocation studies have made the unrealistic assumption that all hopping devices know the overall state of the entire network and each device's current state. Recent work has proposed the most realistic distributed network environment-based relocation algorithms that do not require sharing all information simultaneously. However, since the shortest path-based algorithm performs communication and movement requests with terminals, it is not suitable for an area where the distribution of obstacles is uneven. The proposed scheme applies a simple Monte Carlo method based on relay nodes selection random variables that reflect the obstacle distribution's characteristics to choose the best relay node as reinforcement learning, not specific relay nodes. Using the relay node selection random variable could significantly reduce the generation of additional messages that occur to select the shortest path. This paper's additional contribution is that the world's first distributed environment-based relocation protocol is proposed reflecting real-world physical devices' characteristics through the OMNeT++ simulator. We also reconstruct the three days-long disaster environment, and performance evaluation has been performed by applying the proposed protocol to the simulated real-world environment.

• Journal of IKEEE
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• v.17 no.1
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• pp.1-9
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• 2013

The quantitative evaluation of DEM(Digital Elevation Map) is very important to the assessment of the effectiveness for the applied 3D image analysis technique. This paper presents a new quantitative evaluation method of 3D reconstruction process by using synthetic images. The proposed method is based on the assumption that a preacquired DEM and ortho-image should be the pseudo ground truth. The proposed evaluation process begins by generating a pair of photo-realistic synthetic images of the terrain from any viewpoint in terms of application of the constructed ray tracing algorithm to the pseudo ground truth. By comparing the DEM obtained by a pair of photo-realistic synthetic images with the assumed pseudo ground truth, we can analyze the quantitative error in DEM and evaluate the effectiveness of the applied 3D analysis method. To verify the effectiveness of the proposed evaluation method, we carry out the quantitative and the qualitative experiments. For the quantitative experiment, we prove the accuracy of the photo-realistic synthetic image. Also, the proposed evaluation method is experimented on the 3D reconstruction with regards to the change of the matching window. Based on the fact that the experimental result agrees with the anticipation, we can qualitatively manifest the effectiveness of the proposed evaluation method.

• Journal of Environmental Impact Assessment
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• v.24 no.2
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• pp.134-153
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• 2015

When making urban planning, it is important to understand climate effect caused by urban structural changes. Seoul city applies UPIS(Urban Plan Information System) which provides information on urban planning scenario. Technology for analyzing climate effect resulted from urban planning needs to developed by linking urban planning scenario provided by UPIS and climate analysis model, CAS(Climate Analysis Seoul). CAS develops for analyzing urban climate conditions to provide realistic information considering local air temperature and wind flows. Quantitative analyses conducted by CAS for the production, transportation, and stagnation of cold air, wind flow and thermal conditions by incorporating GIS analysis on land cover and elevation and meteorological analysis from MetPhoMod(Meteorology and atmospheric Photochemistry Meso-scale model). In order to reflect land cover and elevation of the latest information, CAS used to highly accurate raster data (1m) sourced from LiDAR survey and KOMPSAT-2(KOrea Multi-Purpose SATellite) satellite image(4m). For more realistic representation of land surface characteristic, DSM(Digital Surface Model) and DTM(Digital Terrain Model) data used as an input data for CFD(Computational Fluid Dynamics) model. Eight inflow directions considered to investigate the change of flow pattern, wind speed according to reconstruction and change of thermal environment by connecting green area formation. Also, MetPhoMod in CAS data used to consider realistic weather condition. The result show that wind corridors change due to reconstruction. As a whole surface temperature around target area decreases due to connecting green area formation. CFD model coupled with CAS is possible to evaluate the wind corridor and heat environment before/after reconstruction and connecting green area formation. In This study, analysis of climate impact before and after created the green area, which is part of 'Connecting green network across the north and south in Seoul' plan, one of the '2020 Seoul master plan'.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.12
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• pp.874-880
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• 2019

This paper introduces a method which can be effectively used for the path planning of UAV in a realistic map which has mountainous terrains, air defense networks and radars based on the Visibility Graph. Existing studies of Visibility Graph have been studied mainly for simple shape obstacles in 2-dimensional environment such as self-driving cars which avoid buildings. However, for UAV, Visibility Graph must be used in 3-dimensional environment for the variance of altitude. This occurs significant elapsed time increase because of the increase of the amount of the visibility of node sets. To solve this problem, this paper decrease the number of nodes which consists the complex terrain environments using convex hull based on Layered Visibility Graph. With convex hull method, this paper confirmed that the elapsed time is decreased about 99.5% compared to the case which has no decrease of the number of nodes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1363-1368
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• 2016

Fast rendering speed is one of key functions to provide realistic scenes in flight simulator. However, since flight simulator mostly operates with high volume terrain data, rendering speed is reduced and changed very rapidly when it handles file containing too much vertexs. So, previous schemes make use of Level of Details (LOD) scheme to prevent this problem. But, since LOD is applied after the large number of vertexs are detected, transition between scenes is not completely smooth. To solve this problem, in this paper, we propose a new dynamic LOD scheme which controls LOD level in advance through prediction of vertex overload. To verify the proposed scheme, we implement the proposed scheme in our flight simulation through OpenSceneGraph(OSG) and identify the reduced number of vertexs and enhanced Frame Per Second (FPS) by comparing real data with predicted one.