• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.1
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• pp.1-9
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• 2001

BGK schemes are developed by improving the standard BGK numerical method. Shceme 1 uses the Osher's Godunov type solution and scheme 2 are developed to overcome the problems of scheme 1.The improved schemes show many unique properties such as entropy condition, positivity condition, higher order gas evolution model, which lead to an high degree of robustness and accuracy. The scheme 2 especially overcomes the shortcomings of the scheme 1 and posseses many superior properties that cannot be found ohter numerical schemes, and is expected to apply various problems with high accuracy and robustness.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.615-619
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• 2010

4대강 살리기 프로젝트 중 하나인 금강 살리기에는 현재 금남보, 금강보, 부여보가 신설 예정이다. 본 연구에서는 금강 살리기 사업 중 부여보에 대하여 계획홍수량인 100년빈도 유량의 흐름 예측을 위한 1 2차원 수치해석과 수리적인 형상을 실제 흐름으로 관찰하기 위한 수리모형실험을 실시하여 부여보의 치수안정성을 검토 및 분석하였다. 본 연구를 위하여 1차원 수치해석은 HEC-RAS모형, 2차원 수치해석은 SMS RMA2 모형을 사용하였다. 수리모형 실험은 부여보 기준 상 하류 3km 구간에 대하여 축척 1/60 정상모형으로 제작하였다. 그 결과 부여보 상 하류구간에서 원활한 흐름특성이 나타났으며, 100년빈도 유량에 대하여 수치해석과 수리모형실험 모두 계획홍수위를 넘지 않는 것으로 나타났다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.187-195
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• 2012

This paper deals with numerical computations of cryogenic flows around turbopump inducer. Firstly, we introduce numerical methods to compute compressible/incompressible cryogenic two-phase flow. As a validation problem, computation results of 2 dimensional/axi-symmetric cryogenic flow will be presented. In this process, various cavitation model will be compared. Finally, numerical simulation of 3 dimensional turbopump inducer will be presented.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.346-346
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• 2022

본 연구에서는 GPU(Graphic Processing Unit) 가속 분포형모형을 실제 유역에 적용하여 강우 유출모의 결과의 정확성과 모의시간의 효율성에 대한 분석을 수행하였다. 분포형모형의 지배방정식은 운동파모형과 Green-Ampt모형으로 구성되어 있으며, 운동파모형은 유한체적법을 이용하여 이산화 하였다. GPU 가속 모형은 CUDA(Compute Unified Device Architecture) 포트란(Fortran)을 사용하여 개발된 모형으로 수치모의시 연산시간 단축을 고려한 모형이다. 모형의 정확성과 효율성은 미호천 유역에서 발생하는 강우유출현상에 GPU 가속 운동파모형을 적용하여 분석하였다. 수치모의 결과값은 대상유역에 속한 수위관측소의 관측값과 비교하여 정확성을 검증하였고, 수치모의 소요시간은 CPU(Central Processing Unit) 기반 운동파모형의 수치모의 소요시간과 비교하여 효율성을 검증하였다. GPU 가속 운동파모형의 수치모의 결과는 관측값과 유사한 결과를 나타냈으며, 수치모의 소요시간은 본 연구에 사용된 장비를 기준으로 최대 100배 정도 단축되었다.

• 건강소식
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• v.36 no.3
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• pp.28-29
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• 2012

건강검진을 받으러 가면 가장 먼저 하는 것이 작은 컵에 소변을 담아 오는 소변검사다. 온몸을 돌고 돌아 배출된 소변은 내 몸 상태를 말해준다. 소변검사 후 소변 속 숨겨진 수치로 내 몸 상태를 점검해 보자.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.19 no.3
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• pp.229-236
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• 2001

One of the basic tasks in hydrological analysis is to delineate drainage basins and channel networks. Characteristics of channel networks and drainage basin parameters have been used widely in hydrologic calculation and modeling. DEMs(Digital Elevation Models) are generally used to automatically map the channel networks and to delineate drainage basins. This paper presents an effort to analyze basin characteristics using various DEMs. The quantitative analysis of channel networks begins with Horton's method of classifying stream according to Horton orders in hydro-geomorphy. HGSIS(Hydro-Geo-Spatial Information System) is possible to extract parameters. Usually, hydrologists. surveyors and GSIS researchers have some difficulties in accessing satellite images and in extracting DEMs from them. Therefore, the extracted DEMs from contours of digital map is widely used to have the basic works of hydrological analysis. This study presents proper DEMs to calculate Horton's orders, width function, drainage area, main channel length, total channel length, basin elevation and basin slope at digital map of 1:25,000 scale.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.5
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• pp.537-546
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• 2008

The digital map has been updated in every five years in the past. However, it has been changed to make corrections and updated in every two years for metropolitan region and every four years for other regions since year 2008. Although, the correctness and reliability were decreased and updating work is being delayed due to the updating work in a lump. The period update spends a lot of money because this method uses aerial photogrammetry, and the digital map has the time gap between periods. Therefore, this study provides information necessary for digital map produced by the government and develops digital map production system based on objects which can be updated frequently in order to save state and local government budgets that double investment are generated to update digital map. In order to analyze usefulness of the developed system, subject area was selected and errors of updated data were analyzed. As the result of analysis, checked 66 errors were corrected and saved in the database.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.1
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• pp.77-88
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• 2005

Direct Georeferencing (DG) is based on the direct measurement of the projection centers and rotation angle of sensor through loading the GPS and INS in aircraft. The methods can offer us to acquire the exterior orientation parameters with only minimum GCPs, even the ground control process could be completely skipped. In this study, a CCD camera is simultaneously used in GPS/INS, and acquired CCD image through Direct Georeferencing produce digital orthoimage. In this process, methods of combining sensor and digital orthoimage are examined and estimated. For the comparison of the positioning accuracy digital orthoimage through Direct Georeferencing, GCPs determined by GPS surveying are used. Two digital orthoimage are produced; one with a few GCP and the other without them. The produced maps can be used to correct or revised 1:1,000 or 1:5,000 scale maps accordingly.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.2
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• pp.141-147
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• 2011

This study analyzed the issues and its usefulness of drawing small-scale digital map by using the large-scale digital map which was producted with high-resolution digital aerial photograph which are commonly photographed in recent years. To this end, correlation analysis of the feature categories on the digital map was conducted, and this map was processed by inputting data, organizing, deleting, editing, and supervising feature categories according to the generalization process. As a result, 18 unnecessary feature codes were deleted, and the accuracy of 1/5,000 for the digital map was met. Although the size of the data and the number of feature categories increased, this was proven to be shown due to the excellent description of the digital aerial photograph. Accordingly, it was shown that drawing a small-scale digital map with the large-scale digital map by digital aerial photograph provided excellent description and high-quality information for digital map.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.5
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• pp.441-448
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• 2011

Lately, digital restitution was became common using digital aerial photos. Therefore, we can obtain three-dimensional data. As a plotting-maker is checked by naked eye, plotting original data is very useful for making reliable three-dimensional data including contour and elevation point layers. In this study, we want to make precise and accurate digital elevation model using plotting original data. Contour and elevation point layers was extracted in digital map and break line was extracted in plotting original data. And then, compared both of results. For comparison, we selected slight slope and complex topography area like a residence area, mountain and agricultural land. We extracted break line deleting layer until obtaining ideal digital elevation model. As the results, We could extract contour, elevation points, eight road and two boundary layers using break lines. And We could obtain precise elevation model. Editing break lines, the distortion of digital elevation model could be minimized in the complex and sharp slope area.