• International Journal of CAD/CAM
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• 제8권1호
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• pp.21-28
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• 2009

In the present work, an attempt has been made to construct branching surface from 2-D contours, which are given at different layers and may have branches. If a layer having more than one contour and corresponds to contour at adjacent layers, then it is termed as branching problem and approximated by adding additional points in between the layers. Firstly, the branching problem is converted to single contour case in which there is no branching at any layer and the final branching surface is obtained by skinning. Contours are constructed from the given input points at different layers by energy-based B-Spline approximation. 3-D curves are constructed after adding additional points into the contour points for all the layers having branching problem by using energy-based B-Spline formulation. Final 3-D surface is obtained by skinning 3-D curves and 2-D contours. There are three types of branching problems: (a) One-to-one, (b) One-to-many and (c) Many-to-many. Oneto-one problem has been done by plethora of researchers based on minimizations of twist and curvature and different tiling techniques. One-to-many problem is the one in which at least one plane must have more than one contour and have correspondence with the contour at adjacent layers. Many-to-many problem is stated as m contours at i-th layer and n contours at (i+1)th layer. This problem can be solved by combining one-to-many branching methodology. Branching problem is very important in CAD, medical imaging and geographical information system(GIS).

• 한국콘텐츠학회논문지
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• 제16권2호
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• pp.558-565
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• 2016

최근 3D 프린팅 기술은 의료에 여러 방향으로 접목되고 있다. 이에 본 연구에서는 의료영상의 표준인 DICOM 영상을 이용하여 만든 3차원 영상을, 3D 프린팅으로 출력하여 그 형상표면의 정밀성을 검토하고자 하였다. 실험은 동물 뼈를 피사체로 의료영상을 획득하였으며, 3D 프린팅 출력을 위해 STL 파일로 변환하는 과정을 거친 후 피사체 형상을 출력하였다. 최종적으로 원본 동물 뼈 와 3D 프린팅에서 얻은 3차원 형상을 3D Scanner로 획득한 후 3차원 모델링을 서로 병합(Merge)하고 그 차이를 비교하였다. 결과분석은 시각적 형상비교, 모델링의 Scale 값에 대한 색상(Color)비교, 수치적 형상비교를 하였다. 형상표면은 시각적으로는 구분이 어려웠으며, 수치적 형상비교는 X, Y, Z 좌표가 있는 임의의 4곳에서 측정된 값으로 비교하였다. 병합된 모델링의 형상표면은 원본 피사체(동물 뼈)에 비해 평균 -0.49 mm 만큼 3D프린팅으로 출력된 형상에서 작게 나타났다. 하지만 모든 형상 표면이 균일하게 작아지진 않았으며, 실험에서는 그 차이가 -0.83 mm 내에 있었다.

• 패션비즈니스
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• 제16권6호
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• pp.36-51
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• 2012

Quilting, a technique to join two or more layers of fabrics, has long been used in the textile and fashion sectors. To evaluate dimensional effect of quilting that changes according to the characteristics of fabrics, 3D scanning method is employed in this study. Goal of this study is to interpret how fabric's composition, stiffness, thickness, and weight affect the appearance when quilted fabrics are used in a garment. Surface reconstruction method based on 3D scanning is used as a research method to evaluate the changing appearance depending on the material properties quantitatively with the quilting method. Besides, exemplary virtual clothing is realized through a virtual quilting method in 3D digital clothing system based on the properties of fabrics.

• Current Optics and Photonics
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• 제2권2호
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• pp.172-178
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• 2018

We propose a precise 3D endoscopic technique for medical and industrial applications. As the 3D measuring principle, the continuously scanning structured illumination microscopy (CSSIM), which enables to obtain 3D sectional images by the synchronous axial scanning of the target with the lateral scanning of the sinusoidal pattern, is adopted. In order to reduce the size of the probe end, the illumination and detection paths of light are designed as coaxial and a coherent imaging fiber bundle is used for transferring the illumination pattern to the target and vice versa. We constructed and experimentally verified the proposed system with a gauge block specimen. As the result, it was confirmed that the 3D surface profile was successfully measured with $16.1{\mu}m$ repeatability for a gauge block specimen. In order to improve the contrast of the sinusoidal illumination pattern reflected off on the target, we used polarizing optical components and confirmed that the visibility of the pattern was suitable in CSSIM.

• Journal of Mechanical Science and Technology
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• 제15권11호
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• pp.1541-1547
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• 2001

The non-dimensional fin length for optimum heat loss from a thermally asymmetric rectangular fin is represented as a function of the ratio of the bottom surface Biot number to the top surface Biot number, fin tip surface Biot number and the non-dimensional fin width. Optimum heat loss is taken as 98% of the maximum heat loss. For this analysis, three dimensional separation of variables method is used. Also, the relation between the ratio of the bottom surface Biot number to the top surface Biot number and the ratio of the right surface Biot number to the left surface Biot number is presented.

• 대한기계학회논문집A
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• 제30권5호
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• pp.496-504
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• 2006

Wear of engine valves and seat inserts is a major factor affecting engine performance. In order to improve quality and life of valve assemblies, wear mechanism and 3-D surface topography should be analyzed according to operating conditions of the engine. After developing an engine simulator that generates valve speed up to 90Hz and temperature up to $900^{\circ}C$ as well as controls test load, wear experiments have been conducted for two different engine speeds as 10Hz and 25Hz. In order to observe the wear characteristics and monitor surface conditions of the valve assemblies, a cost-effective 3-D wear analysis system based on the shape from focus(SFF) and machine vision has been fabricated in this paper. 3-D surface topography of the valve assemblies has been analyzed to understand the wear behavior according to operating conditions of the engine. Consequently, wear volume of the valve assemblies is quantized by using the developed 3-D wear analysis system.

• 정보처리학회논문지A
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• 제14A권3호
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• pp.133-140
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• 2007

SWBF(shrink-wrapped boundary face) 알고리즘은 조직되지 않은 3차원 측정점으로부터 표면을 재구성하기 위해 최근에 제안된 방법이다. 본 논문에서는 SWBF 알고리즘의 표면 중복문제를 제기하고, 이를 해결하기 위한 개선된 표면 재구성 방법을 제안한다. 제안된 방법은 경계셀이 아닌 모든 셀들을 내부셀과 외부셀로 구분하고, 개선된 경계면의 정의를 이용해 초기메쉬에서 표면의 중복이 발생하지 않도록 하였다. 또한, 측정 방향에 따라 표면 샘플링의 조밀도가 차이가 나는 일반적인 3차원 스캐너로부터 추출된 데이터의 처리를 위해 셀 영상에서 2차원 연결성을 정의하여 사용하였다. 실험을 통해 제안된 방법이 SWBF 알고리즘의 표면중복문제를 극복하는데 매우 유용함을 알 수 있었다.

• Design & Manufacturing
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• 제15권3호
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• pp.7-12
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• 2021

Plastic injection molds used for rapid heating and cooling must minimize surface damage due to friction and maintain excellent thermal and low electrical conductivity. Accordingly, various surface treatments are being applied. The properties of Al₂O₃ coating and DLC coating were compared to find the optimal surface treatment method. Al₂O₃ coating was deposited by thermal spray method. DLC films were deposited by sputtering process in room temperature and high temperature PECVD (Plasma enhanced chemical vapor deposition) process in 723 K temperature. For the evaluation of physical properties, the electrical and thermal conductivity including surface hardness, adhesion and wear resistance were analyzed. The electrical resistance of the all coated samples was showed insulation properties of 24 MΩ/sq or more. Especially, the friction coefficient of high temp. DLC coating was the lowest at 0.134.

• 대한치과기공학회지
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• 제40권4호
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• pp.231-237
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• 2018

Purpose: The development of the dental technology industry has digitized the dental process. Definition of Digitalization of Dental Implantation Digitalization is the process of model making and prosthodontic processing using 3D CAD and CAM. Currently, it is becoming popular due to the spread of various devices. However, precision evaluation at this stage is an important factor in precision-based dental procedures. Therefore, in this study, we want to analyze the precision of the processed body made with digital dental machine. Methods: The accuracy of digital dental pore devices was evaluated. Specimens were fabricated with 5 types of 3D printers. The external shape was measured with the prepared specimen. The surface roughness was measured. Results: As a result, precision was excellent in order of EP2 specimen, EP1 specimen, and EA2 specimen. The precision of EP3 specimen and EA1 specimen is not excellent. And the precision of the specimen processed with polymer 3D printer is excellent. The accuracy of LCPS type polymer 3D printers is considered to be excellent. Conclusion : 1. Observation of the shape The 3D printer for LCPS system and the 3D printer for SLM $40{\mu}m$ system were found to be precisely processed. 2. Surface roughness results The LCPS system polymer 3D printer has been shown to have a precise surface.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제12권5호
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• pp.229-236
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• 2023

3D 출력된 의료용 임플란트(implant) 부품은 보통 표면에 결함이 발생되므로, 출력 후 표면을 검사하는 과정이 필요하다. 자동화된 표면 검사를 수행하기 위해서는 임플란트를 3D 스캔하여 점군(point cloud)과 같은 스캔 모델로 복원하는 방법이 효과적이다. 스캔 모델을 구성할 때, 임플란트는 일반적인 3D 출력 제조 부품과 다른 특성들을 가지므로, 임플란트의 형태와 재료의 특성에 대한 고려가 필요하다. 본 논문에서는 의료용 임플란트 부품의 한 종류인 금속 bone-plate의 3D 출력물에 대해 스캔 모델로 복원하는 방법을 제안한다. 다각도의 시점에서 3D 스캔을 수행하여 다수의 부분 스캔 데이터를 생성한 뒤, 이들에 대해 정렬(alignment)과 정합(merging)을 수행하여 스캔 모델로 복원한다. 또한, 실험을 통해 스캔 모델로 복원하는 과정을 보인다.