• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.668-671
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• 2010

Comparative study on propellant modeling has been investigated using a non-dimensional method and an one-dimensional method. The propellant location in the chamber can not be described by the non-dimensional method. It is, however, possible for the one-dimensional method to describe. Therefore, the analysis of the interior ballistics according to the propellant arrangements has been performed by the one-dimensional method. The negative differential pressure in the chamber could be predicted and the necessity of the one-dimensional modeling for the analysis of the interior ballistics has been confirmed.

• Geophysics and Geophysical Exploration
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• v.18 no.4
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• pp.216-222
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• 2015

Airborne transient electromagnetic (ATEM) surveying was introduced several decades ago in the mining industry to detect shallow conductive targets. However, conventional ATEM systems have limited depth of investigation because of weak signal strength. Recently, the grounded electrical source airborne transient electromagnetic (GREATEM) system was proposed to increase the depth of investigation. The GREATEM is a semi-airborne transient electromagnetic system because a long grounded wire is used as the transmitter. Traditionally, ATEM sounding data have been interpreted with 1D earth models to save the computing time because modern ATEM systems generally collect large data sets. However, the GREATEM 1D modeling requires numerical integration along the wire, so it takes much more time than the 1D modeling of conventional ATEM. In this study, the adaptive Born forward mapping (ABFM) was applied to the ATEM 1D modeling because the ABFM is incommensurably faster than the ordinary GREATEM 1D modeling. Comparing the results from ordinary and ABFM 1D modeling, it was confirmed that the ABFM can be applied to the 1D modeling of GEATEM.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.340-348
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• 2003

비접근지역이나 넓은 지역의 3차원 위치정보를 취득하기 위하여 본 연구에서는 KOMPSAT-1호 EOC 스트립 영상과 헤더자료를 이용한 3차원 기하모델링 기법을 개발하고 오차특성을 분석하였다. ECEF 좌표계로 제공되는 위성 헤더자료를 위성궤도 모델링에서 일반적으로 사용되는 ECI 좌표계로 모델링하는 경우와 ECEF 좌표계로 모델링하는 경우에 대해 비교 분석하고 단영상으로 제공되는 KOMPSAT-1호 EOC 영상을 스트립영상으로 재구성한 후 기준점 배치에 따른 오차보정기법을 제시하고 오차특성을 분석하였다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.1
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• pp.1-8
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• 2006

Effective three dimensional modeling becomes essential in a wide range of drawings, such as construction, machinery and design. In particular, it has been developed as the tool enabling reverse design. Three dimensional modeling requires rapidity, accuracy and tangibility. Data acquisition methods for modeling including contact type coordinate measurement machine, LASER scanner, pattern scanner and digital photogrammetry. In this study, we try to analyze modeling techniques as well as introduce three dimensional modeling using pattern scanner. In addition, this study conducts three dimensional modeling using OPTO-Top pattern scanner with distinguished accuracy and rapidity, and then compare efficiency with digital photogrammetry. And, this study attempts to form environment that enables to turn around models on web in three dimensional ways.

• Geophysics and Geophysical Exploration
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• v.11 no.4
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• pp.318-325
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• 2008

Assigning an exact boundary condition is of great importance in three-dimensional (3D) magnetotelluric (MT) modeling, in which no source is considered in a computing domain. This paper presents a 3D MT modeling algorithm utilizing a Dirichlet condition for a 2D host. To compute boundary values for a model with a 2D host, we need to conduct additional 2D MT modeling. The 2D modeling consists of transverse magnetic and electric modes, which are determined from the relationship between the polarization of plane wave and the strike direction of the 2D structure. Since the 3D MT modeling algorithm solves Maxwell's equations for electric fields using the finite difference method with a staggered grid that defines electric fields along cell edges, electric fields are calculated at the same place in the 2D modeling. The algorithm developed in this study can produce reliable MT responses for a 3D model with a 2D host.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.394-399
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• 2003

도시 지역의 대부분을 차지하는 건물에 대한 3차원 정보는 도로, 교통 등의 시설물관리시스템 구축, 도로계획, 택지개발, 도시계획 등 여러 분야에 필요하다. 현재 항공사진, 고해상도 위성영상, LiDAR 자료, 수치사진측량 시스템 등의 보급과 분석 알고리즘의 발전으로 인하여 도시지역 건물 3차원 모델링에 대한 연구가 활발히 진행되고 있는데, 그 중에서 정밀한 DSM 취득이 가능한 LiDAR 자료가 도시지역 건물 3차원 모델링에 가장 유망한 자료이다. 그러나 LiDAR 자료만을 이용할 경우에는 선형화 과정 등의 수작업이 많이 들어가고, 주관적인 재구성과정이 들어가야 하는 문제점이 있다. 따라서 본 연구에서는 수치지도를 LiDAR 자료와 같이 이용하여 건물 3차원 모델링시 작업자의 수동적인 과정을 단축하였다. 항공사진과 해석도화기를 이용한 정확도 평가 결과 1:5,000 수치지도 정확도 규정을 만족하는 도시지역 건물 3차원 모델링이 가능하였고, 비교적 자동화된 공정을 이루었다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.1
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• pp.19-30
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• 2007

Modeling 3D buildings is an essential process to revive the real world into a computer. There are two ways to create a 3D building model. The first method is to use the building layer of 1:1000 digital maps based on high density point data gained from airborne laser surveying. The second method is to use LiDAR point data with digital images achieved with LiDAR. In this research we tested one sheet area of 1:1000 digital map with both methods to process a 3D building model. We have developed a process, analyzed quantitatively and evaluated the efficiency, accuracy, and reality. The resulted differed depending on the buildings shape. The first method was effective on simple buildings, and the second method was effective on complicated buildings. Also, we evaluated the accuracy of the produced model. Comparing the 3D building based on LiDAR data and digital image with digital maps, the horizontal accuracy was within ${\pm}50cm$. From the above we derived a conclusion that 3D building modeling is more effective when it is based on LiDAR data and digital maps. Using produced 3D building modeling data, we will be utilized as digital contents in various fields like 3D GIS, U-City, telematics, navigation, virtual reality and games etc.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.3
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• pp.285-292
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• 2016

In this study, FE-BE direct coupling methods of 1D and 2D problems are considered for the pontoon-type floating structure and the difference of the modeling dimensions is investigated for the hydroelastic response. The modeling dimensions are defined as the 1D problem consisting 1D beam-2D fluid coupling and the 2D problem consisting 2D plate-3D fluid coupling with zero-draft assumption. For case studies, hydroelastic responses of the 1D Problem are compared to those of the 2D Problem for a wide range of aspect ratio and regular waves. It is shown that the effects of the elastic behavior are increased by decreasing the incident wavelength, whereas the effects of the rigid behavior are increased by increasing the incident wavelength. In 2D problem, the incident wave angle can be considered, and slightly more accurate results can be obtained, but the computational efficiency is lower. On the other hand, in 1D problem with plate-strip condition, the incident wave angle cannot be considered, but when the aspect ratio is large, the overall responses can be analyzed through a simplified model, and the computational efficiency can be improved.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.171-174
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• 2004

본 논문은 Hspice 를 사용한 달팽이관 생역학의 능동적이며 선형적인 1 차 그리고 2 차원 모델링을 보여준다. Hspice 모델링의 장점은 달팽이관 생역학을 아날로그 IC 칩으로 구현할 수 있다는 점이다. 즉 Biochip 으로 설계하는데 활용된다. 본 논문은 달팽이관 생역학을 어떻게 전기회로 모델화한 뒤, 다시 어떻게 Hspice 코드로 표현하는 가를 보여준다. 달팽이관 회로가 Hspice 코드 실행을 위해 변형되어야만 하는 과정을 상세히 보여준다. 1 차원의 결과와 2 차원의 결과를 비교하고 있다.

• Geophysics and Geophysical Exploration
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• v.8 no.3
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• pp.207-217
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• 2005

We present a new approximate formulation of the integral equation (IE) method for models with variable background conductivity. This method overcomes the standard limitation of the conventional If method related to the use of a horizontally layered background only. The new approximate IE method still employs the Green's functions for a horizontally layered 1-D model. However, the new method allows us to use an inhomogeneous background with the IE method. The method was carefully tested for modeling the EM field for complex structures with a known variable background conductivity. It can find wide application in modeling EM data for multiple geological models with some common geoelectrical features, like a known inhomogeneous overburden, or salt dome structures.