• 대한의용생체공학회:의공학회지
• /
• 제7권2호
• /
• pp.133-138
• /
• 1986

Abstract In a conventional digital sector scan system in the ultrasound medical imaging, the sampling space is in the polar coordinates while the display space is in the cartesian coordinates, which necessitates a coordinate transformation process resultion process resulting the overall system very complex and bulky. In this paper we propose a new architecture of the Digital-Scan-Converter (DSC) for the ultrasound sector scan system in which sampling space is the same as the display space, so the data are displayed as they are acquired without any interpola- tion process required. To implement the above real time DSC. two frequency synthesizes with very high switching time and a low-pass filter are required. The former determines the precise location of the data points and the latter fills the gap betw- een pixels in the horizontal direction.

• 한국정밀공학회지
• /
• 제19권10호
• /
• pp.147-155
• /
• 2002

In the stereolithography process, the accuracy of product depends on laser power, scan speed, scan width, scan pattern, layer thickness, resin characteristics and so on. Therefore, appropriate process parameters are required for an accurate prototype. This paper presents a method to determine the key process parameters, i.e., laser scan speed, hatching space, and layer thickness based on scan length, scan area, and layer slope. In order to determine these parameters, three neural networks are employed to represent operator’s experience and knowledge. Optimum values on scan speed, hatching space and layer thickness are recommended to improve the surface roughness and build time on the developed SLA machine.

• Journal of Korean Dental Science
• /
• 제16권2호
• /
• pp.149-155
• /
• 2023

Purpose: The purpose of this study was to evaluate whether the presence of a space maintainer affects the accuracy of an intraoral scanner. Materials and Methods: The maxillary primary first molar typodont tooth was removed from the primary dentition typodont model and a band and loop type space maintainer was delivered. After the model was connected to a dental phantom, intraoral scan was performed using TRIOS 4 (3Shape A/S, Copenhagen, Denmark). The scan was repeated with the same technique without the space maintainer. Each scan was performed 10 times. All scan files into a GOM inspect 2018 software and evaluated the accuracy. The accuracy was evaluated on trueness and precision, and calculated using the root mean square value. Result: When there was a space maintainer in the oral cavity, the trueness value was 0.10±0.02 mm and the precision value was 0.15±0.03 mm. In the absence of the space maintainer, the trueness value was 0.12±0.03 mm and the precision value was 0.16±0.04 mm. There were no significant differences depending on the presence of a space maintainer (P>0.05). Conclusion: Within the limits of this study, the accuracy of the intraoral scanner was not influenced by the presence of space maintainer.

• 한국산학기술학회논문지
• /
• 제17권2호
• /
• pp.227-232
• /
• 2016

3D 인체형상자료는 인체 적합성이 우수한 제품과 생활공간을 만들기 위해 다양한 분야에서 활용되고 있다. 본 연구는 한국인 인체치수조사 보급사업에서 2013년에 수집한 청소년층 3차원 측정 자료를 기반으로 한국 청소년의 대표 인체치수를 산출하고 대표 인체치수와 가까운 3D 인체형상자료를 선별하는 방법을 제공한다. 먼저 여러 측정항목으로 이루어진 다차원 벡터공간을 요인분석을 통해 둘레성분과 길이성분의 2차원 벡터공간으로 투영하였다. 다음으로 2차원 성분공간에서 마할라노비스 거리를 이용하여 대표 인체치수와 이에 가까운 3D 인체형상자료를 선별하였다. 2차원 성분공간에 나타난 청소년기의 성장패턴을 고려하여 남자는 4개의 연령그룹으로 여자는 3개의 연령그룹으로 구분하였다. 성분점수 계수행렬의 열벡터에 대응하는 고유형상을 이용하여 남자는 13개 측정항목, 여자는 14개 측정항목에 대한 대표 인체치수를 연령그룹별로 계산하였다. 여기서 구한 대표 인체치수와 3D 인체형상자료는 3차원 대표 형상을 만드는 데에 매우 유용하다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2001년도 춘계학술대회 논문집
• /
• pp.1089-1092
• /
• 2001

In the stereolithography process, build parameters are laser power, scan velocity, scan width, bean diameter, layer thickness and so on. These values are determined according to product accuracy and build time. Build time can be reduced by improving of scan velocity, laser power, layer thickness, hatching space and so on. But variation of these parameters influence part accuracy, surface roughness, strength. This paper observed cure properties in various beam diameter. In order to examine these, relationships of scan velocity and cure depth, scan velocity and cure width according to various beam diameter in one scan line are measured. And cure thickness is measured according to beam diameter and scan velocity in scan surface of one layer. For reduction of build time, beam diameter and scan velocity is proposed in stereolithography process.

• 한국BIM학회 논문집
• /
• 제9권2호
• /
• pp.21-28
• /
• 2019

Recently, many scan projects are gradually increasing for maintenance, construction. The scan data contains useful data, which can be generated in the target application from the facility, space. However, modeling the scan data required for the application requires a lot of cost. In example, the converting 3D point cloud obtained from scan data into 3D object is a time-consuming task, and the modeling task is still very manual. This research proposes Scan-to-Geometry Mapping Rule Definition (S2G-MD) which maps point cloud data to geometry for irregular building plane objects. The S2G-MD considers user use case variability. The method to define rules for mapping scan to geometry is proposed. This research supports the reverse engineering semi-automatic process for the building planar geometry from the user perspective.

• 대한전자공학회논문지SP
• /
• 제41권4호
• /
• pp.69-74
• /
• 2004

본 논문에서는 프로젝션 프로파일(PP： Projection Profile) 과 컬러공간변환(CST： Color Space Transform)을 이용하여 라인스캔 카메라(Line-Scan Camera) 영상을 재구성함으로써 LCD 표면의 결함검출 성능을 높이는 알고리즘을 제안하였다. 제안된 알고리즘은 결함을 포함한 RGB 영역 분할, 대표값 추적시스템을 이용한 대표값 추출, 그리고 컬러공간변환을 이용한 Y영상 재구성 방법들로 구성되어 있다. 실험을 통하여 제안한 방법으로 재구성된 영상의 결함검출 성능이 영역카메라(Aerial Camera)의 결함검출 성능보다 우수함을 보였다.

• Investigative Magnetic Resonance Imaging
• /
• 제3권1호
• /
• pp.6-12
• /
• 1999

Echo Planar Imaging (EPI) Spiral Scan 영상을 초고속 자기공명영상 기법으로서 전체 k-space의 데이터를 한번 scan에 다 받을 수 있기 때문에 데이터 측정시간을 100ms 이내로 단축시킬 수 있다. 이러한 초고속 영상 기법은 최근 활발히 연구되고 있는 뇌기능 영상과 관련하여 중요도가 더욱 커지고 있다. EPI는 직각좌표계에서 데이터를 받기 때문에 재구성은 비교적 쉬우나 eddy current를 많이 야기시키는 단점을 가지고 있다. 반면에 Spiral Scan 영상은 먼저 데이터를 원 또는 직각좌표계로 interpolation을 한 후 재구성하여야 하는 단점이 있으나, 상대적으로 eddy current가 작고, 방향과 무관하게 균일한 point spread function을 가지며, 혈류와 관련한 위상이 스스로 rephasing 되어 심장 영상 등에 유리한 장점이 있다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
• /
• 한국우주과학회 2000년도 한국우주과학회보 제9권1호
• /
• pp.15-15
• /
• 2000

No Abstract, See Full Text

• 한국의류산업학회지
• /
• 제13권6호
• /
• pp.966-971
• /
• 2011

This study is designed to develop programs that analyze the distance of clothes from human skin and cross-sectional body figures based on 3D human body scan data, and to verify accuracy and efficiency of the program so that it can be used for clothing fit evaluation and 3D human body research. The auto cross-sectional imaging program was developed by using Visual C++ and OpenGL, and the 3D human body scan data were adopted to measure the space between skin and clothing. The space measurements were obtained by two widely used programs, RapidForm and AutoCAD, and a program devised by the researchers of this study. Measuring time and space measurements from different programs were compared in order to verify accuracy and efficiency of the newly-devised program. As a result, no significant difference was found in the measurements. However, the required time to measure one cross section was different within the significance level of 0.05, and the differences become more remarkable as the number of measuring and the angle of space between skin and clothing increase. Therefore, the program developed by this study is expected to be useful for research on body shapes and fit evaluation based on 3D human body scan data in the fashion field.