• Journal of Computational Design and Engineering
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• 제1권2호
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• pp.96-102
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• 2014

In the field of design and manufacturing, there are many problems with managing dynamic states of three-dimensional (3D) objects. In order to solve these problems, the four-dimensional (4D) mesh model and its modeling system have been proposed. The 4D mesh model is defined as a 4D object model that is bounded by tetrahedral cells, and can represent spatio-temporal changes of a 3D object continuously. The 4D mesh model helps to solve dynamic problems of 3D models as geometric problems. However, the construction of the 4D mesh model is limited on the time-series 3D voxel data based method. This method is memory-hogging and requires much computing time. In this research, we propose a new method of constructing the 4D mesh model that derives from the 3D mesh model with continuous rigid body movement. This method is realized by making a swept shape of a 3D mesh model in the fourth dimension and its tetrahedralization. Here, the rigid body movement is a screwed movement, which is a combination of translational and rotational movement.

• 한국수자원학회논문집
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• 제50권4호
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• pp.263-275
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• 2017

고정확도의 도시침수 모의를 위해서는 물리적 개념에 기반한 통합적 수치해석이 필요하다. 본 연구에서는 Lee et al. (2015)이 개발한 1차원 하수관망, 2차원 범람 모형의 국내 적용성을 검토하고, 과거 도시 홍수 사상의 침수 원인 분석을 수행하였다. 본 모형은 이중배수 개념에 기반하여 멘홀 대신 집수구를 지표면과 하수관망 사이의 교환유량 산정 지점으로 이용하므로 보다 실제와 유사하게 침수 과정을 모의할 수 있을 뿐 아니라 지표면 범람 해석시 건물에 의한 차단 효과를 고려할 수 있다. 개발된 모형의 적용성은 서울 사당 유역에서 발생한 침수 사상에 대해서 재현 모의를 통해 검증하였다. 적용 결과, 본 연구에서 개발된 모형은 실제 침수 피해 영역을 실제와 유사하게 모의 하였을 뿐만 아니라 침수 원인을 보다 자세히 분석할 수 있는 장점을 보여주었다.

• 전자공학회논문지SC
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• 제44권5호
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• pp.55-61
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• 2007

본 논문은 관심 객체 분할을 위한 통계적 모양 모델에 기반한 3차원 능동 모양 모델링 기법을 제안한다. 3차원 모양 모델을 만들려면 포인트 분산 모델(PDM)의 생성이 필수적인데, 이를 위해서는 모든 학습(training) 데이터에 대응하는 특징점(landmark)을 잘 선택해야 한다. 현재까지도 3차원 데이터에서 대응하는 특징점을 선택하는 방법은 주로 수동적으로 선택하거나 2차원 기반 기법 또는 제한된 3차원 기법이 사용되고 있다. 본 논문에서는 최근에 제안된 "3차원 통계적 모양 모델의 자동생성 기법"의 거리 변환(distance transform)과 사면체(tetrahedron) 알고리듬을 사용하여 3차원 통계적 모양 모델을 생성하고 2차원 능동 모양 모델의 모양 모델 학습과 그레이레벨(gray-level) 모델 학습을 개선하여 확장하고, 스케일(scale)과 그레이레벨 모델을 결합한 3차원 능동 모양 모델 알고리듬으로 관심 객체를 분할한다. 본 논문에서는 제안한 방법을 영역 기반 윤곽선 기반 기법 및 2차원 능동모양모델 기법과 그 성능을 비교하여 평가했다.

• 한국측량학회지
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• 제25권6_1호
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• pp.565-574
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• 2007

Because of most current cadastral systems maintain 2D geometric descriptions of parcels linked to administrative records, the system may not reflect current tendency to use space above and under the surface. The land has been used in multi-levels, e.g. constructions of multi-used complex buildings, subways and infrastructure above/under the ground. This cadastre situation of multilevel use of lands cannot be defined as cadastre objects (2D parcel-based) in the cadastre systems. This trend has requested a new system in which right to land is clearly and indisputably recorded because a right of ownership on a parcel relates to a space in 3D, not any more relates to 2D surface area. Therefore, this article proposes a 3D spatial data model to represent geometrical and topological data of 3D (property) situation on multilevel uses of lands in 3D cadastre systems, and a conceptual 3D cadastral model in Korea to design a conceptual schema for a 3D cadastre. Lastly, this paper presents the results of an experimental implementation of the 3D Cadastre to perform topological analyses based on 3D Network Data Model to identify spatial neighbors.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.73-74
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• 2023

The purpose of this study is to derive the cause of the quantity difference and present the considerations when take-off rebar quantity based on BIM model by comparing the quantity of rebar based on BIM model with 2D drawing. This research was limited to take-off the quantity of rebars in the building frame work, and after take-off the quantity of rebars by 3D modeling the 2D drawing of the target building with Revit, the quantity difference was compared with 2D-based software. Therefore, when take-off the quantity of rebars based on the BIM model, instead of take-off the existing 2D-based quantity premium proportion, according to general structural consider development length, lap splice length, covering thickness, reinforcing bars and spacing. In the future, this study is expected to contribute to improving the accuracy of BIM-based frame construction quantity take-off.

• 지적과 국토정보
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• 제45권1호
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• pp.193-205
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• 2015

입체공간에 대한 이용이 증가하면서 기존의 2차원 지적으로는 입체공간에 대한 정보를 관리하는데 한계가 있어 입체공간의 물리적 현황 및 사용권에 대한 정보를 등록 관리할 수 있는 3D 지적이 요구되고 있다. 이번 연구는 입체공간의 이용 현황 분석을 통해 3D 지적에 포함될 수 있는 데이터의 범위를 설정하고, 국제표준인 토지행정도메인모델(LADM)을 기반으로 3D 지적을 이해할 수 있는 개념모델을 설계함으로써 3D 지적시스템의 개발을 위한 기반을 마련하고자 한다.

• 한국산학기술학회논문지
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• 제7권1호
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• pp.57-62
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• 2006

본 논문에서는 3D 의복 착의 시뮬레이션에서 사용되는 3D 의복 모델을 제작하는 시스템을 제안한다. 착의 시뮬레이션을 하기 위해서는 3D 인체모델과 3D 의복 모델이 필요하다. 의복 모델을 디자인하기 위해서는 먼저 작업 Matrix 창을 생성하고 디자이너로부터 2D 피스(Piece)를 디자인한다. 디자인된 피스들을 박음질 선을 이용해 연결하고 마지막으로 디자인된 피스와 박음질 데이터를 사용해 수치 데이터를 생성하여 3D 의복 모델을 만든다. 본 논문에서 제안한 시스템에서는 피스 디자인 모듈, 의복 데이터 읽기/저장 모듈, 착의 시뮬레이션 모듈로 이루어져 있다.

• Imaging Science in Dentistry
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• 제34권1호
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• pp.13-18
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• 2004

Purpose : This study was to evaluate the influence of slice thickness of computed tomography (CT) and rapid protyping (RP) type on the accuracy of 3-dimensional medical model. Materials and Methods: Transaxial CT data of human dry skull were taken from multi-detector spiral CT. Slice thickness were 1, 2, 3 and 4 mm respectively. Three-dimensional image model reconstruction using 3-D visualization medical software (V-works /sup TM/ 3.0) and RP model fabrications were followed. 2-RP models were 3D printing (Z402, Z Corp., Burlington, USA) and Stereolithographic Apparatus model. Linear measurements of anatomical landmarks on dry skull, 3-D image model, and 2-RP models were done and compared according to slice thickness and RP model type. Results: There were relative error percentage in absolute value of 0.97, 1.98,3.83 between linear measurements of dry skull and image models of 1, 2, 3 mm slice thickness respectively. There was relative error percentage in absolute value of 0.79 between linear measurements of dry skull and SLA model. There was relative error difference in absolute value of 2.52 between linear measurements of dry skull and 3D printing model. Conclusion: These results indicated that 3-dimensional image model of thin slice thickness and stereolithographic RP model showed relative high accuracy.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.598-601
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• 2006

The radio signal in GNSS was intentionally designed with two frequencies in order to combat the dispersion error caused by trans-ionospheric propagation. By measuring the path delay independently at the two, widely spaced GPS frequencies, L1 & L2, the TEC along the path from satellite to receiver can be measured directly. The issue with dual frequency measurement of the ionosphere is the calibration of L1/L2 interfrequency biases. L1/L2 interfrequency biases are generated because physical electric signal paths of L1 and L2 circuits are different from each other for both satellites and receiver. Conventionally L1/L2 interfrequency bias is estimated and broadcasted by 2D ionospheric model. In this paper, we estimated IFB (interfrequency bias) by 2D & 3D ionospheric models including real time filter methods and compared the result of those and concluded the merit of 3D tomography model to recover the problem of 2D thin shell model. We confirmed our conclusion by experimental data.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.961-966
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• 2003

In recent, the design of diaphragm which is representative disturbed region in PSC box girder bridge have been performed according to the empirical method or beam theory. But, these methods couldn't be described the behavior of the end diaphragm, and placed reinforcements accurately. As the compressive stress transferred by the web concentrated on the lower parts of diaphragm, it was demonstrated that the basic assumption of 2-D strut-and-tie model for the diaphragm that the compressive stress acts on the upper parts of the diaphragm is wrong. Meanwhile, in this research, after analyzing the variables of end diaphragm, the 2-D strut-and-tie models appropriate to each cases are proposed. And, the problems of 2-D strut-and-tie model were analyzed, so 3-D strut-and-tie model is proposed as well. There is no codes which include the demonstration of safety of 3-D strut-and-tie model. Hence, for nodes, the stresses at the elements which included the singular node in strut-and-tie model were investigated using the finite element analysis. And, the stress states of strut has one direction, so effective stresses were considered at the stage, dimensioning of the model. From the results, 3-D strut-and-tie model could predict the behavior of end diaphragm accurately, and design of reinforcement could be performed economically.