• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1675-1678
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• 2008

어류는 민감하기 때문에 최적화된 어도를 설계하는 것은 매우 어려운 일이다. 이와 같은 문제를 해결하기 위해서, 관찰, 수리모형시험과 같은 방법을 이용한 연구가 주를 이루어 왔다. 최근 들어 어도에 대한 기본 지식의 축적과 CFD 프로그램이 발전함에 따라 수치모의를 이용해 최적 어도를 설계하고자 하는 노력이 활발해 지고 있다. 본 연구에서는 최적 어도 설계를 도모하기 위해서 어류의 휴식을 위해 설치되는 풀(pool) 내의 흐름해석을 수행하였다. 군남홍수조절지를 대상으로 설계도면을 분석하여 3차원으로 변환하여 구조물형상을 구축하였으며, FLOW-3D 모형을 이용하여 흐름을 해석하였다. 휴식 풀 내의 흐름을 모의한 결과 어도 내 월류 수심이 10cm 일 경우, 휴식 풀 내 유속은 풀 내 유입어도의 노치와 잠공부분에서 최대 유속이 0.4m/s로 나타났고, 국부적으로 집중된 유속에 의해 풀 내 순환류가 발생하나, 유속의 범위가 최대 0.15m/s를 넘지 않는 것으로 모의되었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2D
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• pp.311-316
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• 2006

Despite geospatial information systems are widely used in many different fields as a powerful tool for spatial analysis and decision-making, their capabilities to handle realistic 3-D urban environment are very limited. The objective of this work is to integrate the recent developments in 3-D modeling and visualization into GIS to enhance its 3-D capabilities. To achieve a photorealistic view, building models are collected from a pair of aerial stereo images. Roof and wall textures are respectively obtained from ortho-rectified aerial image and ground photography. This study is implemented by using ArcGIS as the work platform and ArcObjects and Visual Basic as development tools. Presented in this paper are 3-D geometric modeling and its data structure, texture creation and its association with the geometric model. As the results, photorealistic views of Purdue University campus are created and rendered with ArcScene.

• Journal of Korea Water Resources Association
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• v.34 no.6
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• pp.577-586
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• 2001

This study proposes a theoretical methodology for deriving a rainfall intensity-duration- frequency (I-D-F) curve using a simple rectangular pulses Poisson process model. As the I-D-F curve derived by considering the model structure is dependent on the rainfall model parameters estimated using the observed first and second order statistics, it becomes less sensitive to the unusual rainfall events than that derided using the annual maxima rainfall series. This study has been applied to the rainfall data at Seoul and Inchon stations to check its applicability by comparing the two I-D-F carves from the model and the data. The results obtained are as followed. (1) As the duration becomes longer, the overlap probability increases significantly. However, its contribution to the rainfall intensity decreases a little. (2) When considering the overlap of each rainfall event, especially for large duration and return period, we could see obvious increases of rainfall intensity. This result is normal as the rainfall intensity is calculated by considering both the overlap probability and return period. Also, the overlap effect for Seoul station is fecund much higher than that for Inchon station, which is mainly due to the different overlap probabilities calculated using different rainfall model parameter sets. (3) As the rectangular pulses Poisson processes model used in this study cannot consider the clustering characteristics of rainfall, the derived I-D-F curves show less rainfall intensities than those from the annual maxima series. However, overall pattern of both I-D-F curves are found very similar, and the difference is believed to be overcome by use of a rainfall model with the clustering consideration.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.2
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• pp.69-77
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• 2022

The 3D spatial model is an analysis framework for solving urban problems and is used in various fields such as urban planning, environment, land and housing management, and disaster simulation. The utilization of drones that can capture 3D images in a short time at a low cost is increasing for the construction of 3D spatial model. In terms of building a virtual city and utilizing simulation modules, high location accuracy of aerial survey and precision of 3D spatial model function as important factors, so a method to increase the accuracy has been proposed. This study analyzed location accuracy of aerial survey and precision of 3D spatial model by each condition of aerial survey for urban areas where buildings are densely located. We selected Daerim 2-dong, Yeongdeungpo-gu, Seoul as a target area and applied shooting angle, shooting altitude, and overlap rate as conditions for the aerial survey. In this study, we calculated the location accuracy of aerial survey by analyzing the difference between an actual survey value of CPs and a predicted value of 3D spatial Model. Also, We calculated the precision of 3D spatial Model by analyzing the difference between the position of Point cloud and the 3D spatial Model (3D Mesh). As a result of this study, the location accuracy tended to be high at a relatively high rate of overlap, but the higher the rate of overlap, the lower the precision of 3D spatial model and the higher the shooting angle, the higher precision. Also, there was no significant relationship with precision. In terms of baseline-height ratio, the precision tended to be improved as the baseline-height ratio increased.

• Journal of Korea Water Resources Association
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• v.36 no.5
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• pp.761-776
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• 2003

Numerical models were employed to investigate the hydrodynamics of water flow in the lake behind a dam and the spillway where supercritical flows and negative pressures are likely to occur. In this study, 2-D model, RMA2 was employed to examine the upstream flow pattern and 3-D CFD model, FLUENT was used to evaluate the three-dimensional flow in the approaching region and flow distributions in the spillways and discharge culverts. The bathymetry and the details of structures were carefully taken into consideration in building the models. The results from applying the 2-D model for the planned Hantan River Dam show that large eddies, the velocity of which reaches up to 1 m/s are occurring in several places upstream of the dam. That means that the 2-D numerical model could be utilized to investigate the two-dimensional flow patterns after the construction of a dam. Three-dimensional numerical results show that the approach flow varies depending on stages and discharge conditions, and velocities at spillways, discharge culverts, and sediment flushing tunnels are differently distributed. The velocity distributions obtained from the numerical model and a hydraulic model at the centerline of spillways 100 m upstream of the dam show reasonably similar results. It is expected that 2-D and 3-D numerical models ate useful tools to help optimize the dam design through investigating the flow patterns in the spillway and at the upstream of the dam, which is not always feasible in hydraulic modeling.

• The KIPS Transactions:PartD
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• v.16D no.3
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• pp.407-416
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• 2009

To support an efficient management of software verification and validation activities, much research has been conducted to predict defects in early phase. And defect prediction models have been proposed to predict defects. But the generality of the models has not been experimentally studied for other software system. In other words, most of prediction models were applied only to the same system that had been used to build the prediction models themselves. Therefore, we performed an experiment to explore generality of major prediction models. In the experiment, we applied three defects prediction models to three different systems. As a result, we cannot find their generality of defect prediction capability. The cause is analyzed to result from a different metric distribution between the systems.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.447-450
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• 2004

B2C 전자상거래 분야의 대표격인 인터넷쇼핑몰은 유통산업의 구조에 큰 영향을 미침에 따라 쇼핑몰의 성공적 구축 및 운영이 주된 이슈로 떠오르고 있다. 본 연구에서는 최근 웹사이트 평가모델로 주목 받고 있는 3C-D-T 모델을 기반으로 보완하여 국내 인터넷쇼핑몰 웹사이트 평가에 보다 최적화된 평가모형을 제시하였다. 평가모형의 보완은 주로 평가영역 부분에서 이루어졌는데, 인터넷 쇼핑몰 웹사이트에서 비교적 비중이 적은 Community 영역의 평가점수가 전체 웹사이트 평가에 주는 영향을 최소화 시키는 의미가 있었다. 그리하여 3C-D-T 모델의 평가영역의 Commerce 항목과 Community 항목을 통합하여 새로이 Com&Com 항목을 구성했고, 그것으로 보다 최적화 된 인터넷쇼핑몰 웹사이트 평가모형을 구축할 수 있었다. 그리고 이 새로운 평가모델로 국내 메이저 종합쇼핑몰 웹사이트들을 분석, 비교평가 하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1750-1754
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• 2010

구조물 주변의 국부세굴에 대한 예측은 현장관측 및 수리실험 결과를 이용한 다양한 경험식과 수리모형 실험, 수치 모의 등을 통하여 이루어진다. 본 연구에서는 최근 국내에서 많이 사용되고 있는 3차원 수치모형인 FLOW-3D의 세굴분석 능력 검토를 제고하기 위하여 민감도 분석을 실시하였다. FLOW 3D의 입력 매개변수는 평균입경(Average particle diameter), 유사 비중(Density of the sediment particle), 한계 무차원 소류력(Critical Shields number), 세굴 조절개수(Scour erosion adjustment), 한계 유사비(Critical sediment fraction), 점착성 유사비(Cohesive sediment fraction), 유사 항력(sediment drag force), 안식각(Angle of repose)이 있다. 이 중에서 평균입경, 안식각, 세굴조절개수, 한계 유사 fraction 등의 매개변수에 대해 초기값을 중심으로 일정 비율로 구분하여 민감도 분석을 실시하였다. 주요 매개변수의 민감도 분석 결과는 수리실험 결과치와 비교 검토 후에 민감도의 변화 범위와 선행하여 조정할 수 있는 매개변수를 제시할 수 있다. 이러한 결과를 바탕으로 수공구조물 주변의 국부 세굴에 관한 해석시 FLOW-3D를 이용한 분석에서 보다 신뢰도 높은 결과 산출이 가능할 것으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.198-202
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• 2011

과거의 하천은 이 치수에 주목적을 두고 하천정비를 실시하였으며, 이 때문에 하천은 직선화되거나 하천구조물을 설치하여 원래의 고유한 특성을 상실한 채 자연적인 모습을 찾아보기 어려운 상황에 이르렀다. 과거와 같은 하천의 난개발은 하천 생태계를 교란하였으며, 하천을 서식처로 삼고 살아가던 많은 동식물이 하천환경의 변화와 파괴로 인해 사라졌거나 생존을 위협받고 있다. 그러나, 최근에는 이러한 하천환경을 과거와 같이 생물의 종다양성이 풍부한 곳으로 만들기 위한 노력이 하천 개발과정에서 다양하게 전개되고 있으며, 이를 위한 연구도 진행되고 있다. 본 연구에서는 하천환경에서 어류의 서식처 보전을 위한 하천유지유량을 산정하기 위해 2차원 생태모델인 River2D 모형을 섬진강 송정지점을 대상으로 하여 적용하였다. 모형의 적용을 위해 송정지점에서의 대표어종을 선정하였으며, 서식처 특성 파악을 위해 하천 수리 및 하도특성을 조사하였다. 조사된 결과를 이용하여 River2D 모형을 구축하였으며, 구축된 모형을 이용하여 송정구간에서 대표어종인 피라미와 갈겨니의 서식처 보전을 위한 생태학적 하천유지유량을 추정하였다. 생태학적 하천유지유량은 모델의 결과와 실제 도입 가능수량 등을 검토하여 최종적인 하천유지를 결정하였으며, 그 결과 송정구간은 $7.0\;m^3/s$이상으로 산정되었다. 본 연구에서는 미시서식처 모형에 의해 생태유지유량을 산정하였으나, 진정한 의미의 생태학적하천유지유량은 수리수문학적 특성뿐만 아니라 생화학적 특성을 고려한 거식적인 관점에서 검토하여야 할 것이다.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.418-421
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• 2007

It is important to maintain information by application or 3D modeling through the satellite and UAV image which is a real world. The prevention business has recognized the need for accurate 3-D geospatial information around the disaster region to identify objects to 3D modeling. In this paper, we presented an approach to create 3D model and loading, processing the image using GIS techniques, and the digital topographic maps were used for the DEM and the features of the area. The result is a implementation of the simple application that illustrates the objects in 3-D. The presented approach will be used for identifying objects and assisting in regional planning around the airfields.