• The KIPS Transactions:PartB
• /
• v.16B no.1
• /
• pp.47-54
• /
• 2009

Automatic object recognition in 3D measuring data is of great interest in many application fields e.g. computer vision, reverse engineering and digital factory. In this paper we present a software tool for a fully automatic object detection and parameter estimation in unordered and noisy point clouds with a large number of data points. The software consists of three interactive modules each for model selection, point segmentation and model fitting, in which the orthogonal distance fitting (ODF) plays an important role. The ODF algorithms estimate model parameters by minimizing the square sum of the shortest distances between model feature and measurement points. The local quadric surface fitted through ODF to a randomly touched small initial patch of the point cloud provides the necessary initial information for the overall procedures of model selection, point segmentation and model fitting. The performance of the presented software tool will be demonstrated by applying to point clouds.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.241-241
• /
• 2017

기후변화로 인하여 강우의 불확실성이 가중되고 홍수, 가뭄 등 물 관련 재해의 발생빈도 및 강도가 증가함에 따라 안정적인 용수공급 등 수자원 관리 및 운영에 어려움을 겪고 있어 예측기반의 수자원 계획 및 운영이 요구되고 있는 실정이다. 우리나라 기상청에서는 2010년 6월 영국기상청과 장기 계절예측시스템의 구축 및 운영에 관한 협정을 체결하였으며 2014년부터 전지구 계절예측시스템 GloSea5(Global seasonal forecasting system version 5)을 현업에 활용하고 있다. GloSea5 모델은 대기(UM), 지면(JULES), 해양(NEMO), 해빙(CICE) 모델이 커플러(OASIS)에 의해 결합된 통합 시스템으로 일단위 자료로 제공된다. 현재 수자원 분야에서는 장기예보자료가 제공되고 있음에도 불구하고 장기예보자료의 불확실성 및 수문 모형 입력자료로의 활용 어려움, 예측자료의 검증 미흡 등으로 기상청에서 제공하는 장기예보를 참고할 뿐 실제로는 과거 관측자료를 기반한 빈도해석 결과를 활용하여 댐 운영 계획을 수립하고 있는 실정이다. 따라서, 본 연구에서는 GloSea5모델에서 제공되는 일 단위 예측 강수량을 수자원 장기이수계획 및 관리에 활용하고자 GloSea5모델의 예측력을 평가하고 수치모델이 가지는 시스템 에러에 대하여 편의보정 및 지점 상세화를 수행하였다. 본 연구의 분석결과는 향후, 저수지 운영계획 및 증가하는 물수요와 불확실한 공급에 대한 의사결정 지원, 가뭄 대비를 위한 물 공급 제한 등에 활용 가능할 것으로 판단된다.

• Korean Journal of Remote Sensing
• /
• v.30 no.6
• /
• pp.755-767
• /
• 2014

In this study, detailed air flow characteristics in an urban areas were analyzed using GIS data and a Computational Fluid Dynamics (CFD) model. For this, a building construction algorithm optimized for Geographic Information System (GIS) data with a vector format (Los Angeles region imagery acquisition consortium 2 geographic information system, LARIAC2 GIS) was used. In the LARIAC2 GIS data, building vertices were expressed as latitude and longitude. Using the model buildings constructed by the algorithm as the surface boundary data in the CFD model, we performed numerical simulations for two building-congested areas in Los Angeles using inflow information provided by California Air Resources Board. Comparing with the inflow, there was a marked difference in wind speed and direction within the target areas, which was mainly caused by the secondarily induced local circulations such as street-canyon vortices, horse-shoe vortices, and recirculation zones. In street canyons parallel to the inflow direction, wind speed increased due to a channeling effect and, in street canyons perpendicular to the inflow direction, vertically well developed vortices were induced. In front of a building, a horse-shoe vortex was developed near the surface and, behind a building, a recirculation zone was developed. Near the surface in the areas where the secondarily induced local circulations, wind speed remarkably increased. Overall, wind direction little (largely) changed at the areas where wind speed largely increased (decreased).

• Journal of the Korea Computer Graphics Society
• /
• v.4 no.1
• /
• pp.79-88
• /
• 1998

Till now there are several rendering models for water and simulating other fluids and their dynamics. Especially in order to generate a curved surface of flexible objects such as liquid and snow, the implicit metaball formulation is widely used in favor of its simplicity and flexibility. This paper proposes one excellent method for generating water droplets, which would be deformed in gravitation field. In previous works, a water droplet was simply represented by approximated curved surfaces of a symmetric metaball. Thus the final result of the rendered water droplet was far from a realistic droplet, because they do not consider the gravitational effect in droplets. We propose a new metaball model for rendering water droplets placed on an arbitrary surface considering the gravitation and friction between droplet and plate. Our new metaball model uses a new vector field isosurface function to control the basic scalar metaball with respect to the norm of gravitational force. In several experiments, we could render a photo-realistic water droplets with natural-looking shadows by applying ray-tracing.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.59 no.4
• /
• pp.1-15
• /
• 2017

Eutrophication of surface waters is of concern worldwide, because it can result in many undesirable water-quality and ecological problems, such as hypoxic 'dead' zones and harmful algal blooms, both associated with considerable economic costs. In this study, we used LSM (Land Surface Model) to simulate nitrogen in five major rivers in the Southern Korean Peninsula. The main objective of this research was to enhance nitrogen data for input of LM3V model in South Korea. Input data for nitrogen fluxes were categorized into three sections including agriculture fertilizer, livestock manure, atmosphere deposition, biological fixation, and sewage pollutants were used as the nitrogen input. For using LM3V model, the nitrogen input data were regenerated by considering states of agriculture and industry in South Korea at a $1/8^{\circ}$ resolution. Then, we simulated stream/river flows and N loads throughout the entire drainage networks in South Korea at a $1/8^{\circ}$ resolution. By using the same parameters for the entire country ($100,210km^2$), composed of 5 river basins with varying climate and land use, the model simulates spatial (11 sites) and temporal (1999~2010) patterns of flows and nitrate-N loads are resonable by comparing observed flow and nitrate-N loads. The r (Pearson's linear correlation) for water temperature, flow and nitrate-N at river were 080~0.93, 0.62~0.92 and 0.5~0.9 respectively. Based on enhanced N input data and model results, we find that LM3V model as land surface model can be applied in South Korea with interaction of atmosphere and land conditions.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.32 no.6
• /
• pp.16-22
• /
• 2004

Unsteady vortex shedding behind a rectangular cylinder near a wall influences both increasing of drag and dynamic stability of heavy vehicle, bridge or building. Incompressible Averaged Navier-Stokes equation with modified ${\varepsilon}-SST$ turbulence model is adapted for investigating the flow field between the rectangular cylinder and the wall. In case the vortex shedding happens, not only the averaged maximum velocity is higher than other cases, but the position of the maximum velocity is closer to the lower surface of rectangular cylinder. On this study, it is confirmed that the vortex shedding behind a rectangular cylinder can be suppressed by the passive control method added by horizontal and vertical fences to the lower surface of rectangular cylinder.

• Korean Journal of Applied Biomechanics
• /
• v.18 no.4
• /
• pp.89-97
• /
• 2008

The purpose of this study was to analyze the foot-pressure distribution of Tennis Shoes for assessing their functionality. 10 university male students (shoe size: 265mm) who had no history of injury in the lower extremity and a normal gait pattern participated in this study. Four types of tennis shoes, most popular in Korea (A, B, C & D company), were selected and tested. Using the PEDAR-X system and PEDAR-X insoles, 4 different motion stages were analyzed for the foot-pressure distribution: (a) straight running; (b) c-cut($45^{\circ}$ left turn running; (c) forehand stroke; and (d) backhand stroke. Results revealed that in all stages, there were no statistically significant differences among the types of shoes; however, descriptive statistics indicated that functionality of shoe types was somewhat different depending on the type of stages. The order in functionality found was C>A>B>D.

• Korean journal of communication and information
• /
• v.32
• /
• pp.7-48
• /
• 2006

The study explores how Korea's major newspaper cover about science news, especially how newspaper frame biotechnology news including new source, news construction ways, coverage trend. The research has a research design to find out coverage pattern or model with frame theory. The result shows that the newspaper has some aspect of frame through out the biotechnology development in the section, theme, source, complexity. The section has been expend to the society and international section, while the theme shift from disease or cancer cure to life itself, genome, or stem cell. In the complexity, the biotechnology news stories have been developed a story plot (event-problem-development-solution). In the climax, the news coverage focuses on the explanation of biotechnology news.

• Journal of Korean Society for Geospatial Information Science
• /
• v.20 no.1
• /
• pp.3-12
• /
• 2012

It is a global trend to give attention to generating precise 3D navigation maps since eco-friendly vehicles have become a critical issue due to environmental protection and depletion of fossil fuels. To date, Mobile Mapping System (MMS) has been a efficient method to acquire the data for generating the 3D navigation maps. To achieve this goal so far in the Mobile Mapping System using the data acquisition method has been proposed to be most effective. For this study the basic RTF filter algorithm was applied to modify to fit MMS quantitative analysis derived floor 99.71%, 99.95% of the highly non-producers to maintain accuracy and high-precision 3D road could create DEM. In addition, the roads that exist within the cars, roadside tree, road cars, such as the median strips have been removed to shields it takes to get results effectively, and effective in practical applications and can be expected to improve operational efficiency is considered.

• Journal of Advanced Navigation Technology
• /
• v.23 no.6
• /
• pp.487-494
• /
• 2019

Recently, interest in and use of drones is increasing. In this study, to provide accurate wind prediction at ultra low altitudes of 150 meters or below, the sensitivity of the physical process parameterization and initial conditions was assessed to select the optimal physical process and initial conditions. For this purpose, GFS and LDAPS data were used as initial and boundary conditions, and 7 experiments were constructed using a combination of PBL schemes such as YSU, RUC, ACM2, and LSM such as Noah, RUC, and Pleim. The experiment conducted for 1 month in April 2018. As a result, the RUC-YSU physical process combination using the GFS initial data showed the best performance. This study is meaningful in establishing an optimal modeling method for ultra low altitude wind prediction through experiments using different initial conditions and combination of physical processes.