• Journal of the Korean Wood Science and Technology
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• 제48권3호
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• pp.283-290
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• 2020

For visual inspection-based wood identification, optical microscopy techniques typically require a relatively large sample size, and a scanning electron microscope requires a clean surface. These novel techniques experience limitations for objects with highly limited sampling capabilities such as important and registered wooden cultural properties. Synchrotron X-ray microtomography (SR-µCT) has been suggested as an effective alternative to avoid such limitations and various other imaging issues. In this study, four pieces of wood fragments from wooden members used in the Manseru pavilion of Bongjeongsa temple in Andong, Korea, wereused for identification. Three-dimensional microstructural images were reconstructed from these small wood samples using SR-µCT at SPring-8. From the analysis of the reconstructed images, the samples were identified as Zelkova serrata, Quercus sect. Cerris, and Pinus koraiensis. The images displayed sufficient spatial resolution to clearly observe the anatomical features of each species. In addition, the three-dimensional imaging allowed unlimited image processing.

• 소성∙가공
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• 제20권7호
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• pp.518-523
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• 2011

The three dimensional geometries of an aluminum open cell foam before and after uniaxial compressive loading were investigated using the X-ray micro CT(computed tomography). Aluminum 6101-T6 open cell foams of 10, 20, 40 ppi (pore per inch) were considered in this work. After the serial sectioning CT images of aluminum foams were obtained from non-destructive X-ray images, the exact 3D structure were reproduced and visualized with commercial image processing program. The relative density ratio was around the 7.0 to 9.0 range, the unit cells showed anisotropic shapes having the different dimensional ratios of 1.1 to 1.3 between the rise and the transverse directions. The yield stress increased with the relative density ratio and the volumetric strain increased proportionally with compressive strain. The plateau stress in the compressive stress-strain curve was caused by the buckling of ligaments.

• 한국음향학회지
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• 제28권2호
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• pp.141-147
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• 2009

본 논문에서는 인체에 유해한 방사능 피폭량이 부챗살 형태의 Fan Beam 보다 상대적으로 적은 원추형 Cone Beam CT 시스템을 사용하여 3차원 영상을 빠르게 구성하기 위한 회전 기반법 알고리즘을 제안하였다. 그리고 계산 속도를 빠르게 하기 위하여 초월함수가 더 적은 3단계 회전 행렬을 이용하여 3차원 영상을 구현하였다. 또한 본 연구에서 구성한 영상을 일반적으로 사용되는 라돈 변환 알고리즘으로 구현된 3차원 영상과 비교하여 영상의 질은 평균적으로 단면 영상 당 10% 정도의 오차를 보이며 미약하게 저하되었으나 영상 구성 속도 면에서는 35배 개선됨을 보였다. 이는 대략 초당 $4{\sim}5$ 프레임을 얻을 수 있는 수치이며 간단한 구조를 가진 피사체라면 보다 많은 프레임을 얻을 수 있어 3차원 동영상을 실시간으로 구현할 수 있는 가능성을 보였다.

• Imaging Science in Dentistry
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• 제33권3호
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• pp.151-159
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• 2003

Purpose: The purpose of this study is to evaluate the effectiveness and usefulness of newly developed personal computer-based software to eliminate the linear artifacts by the metal restorations. Materials and Methods: A 3D CT image was conventionally reconstructed using ADVANTAGE WINDOWS 2.0 3D Analysis software (GE Medical System, Milwaukee, USA) and eliminated the linear artifacts manually. Next, a 3D CT image was reconstructed using V-works 4.0/sup TM/(Cybermed Inc., Seoul, Korea) and the linear artifacts eliminated manually in the axial images by a skillful operator using a personal computer. A 3D CT image was reconstructed using V-works 4.0/sup TM/(Cybermed Inc., Seoul, Korea) and the linear artifacts were removed using a simplified algorithm program to eliminate the linear artifacts automatically in the axial images using a personal computer, abbreviating the manual editing procedure. Finally, the automatically edited reconstructed 3D images were compared to the manually edited images. Results and Conclusion: We effectively eliminated the linear artifacts automatically by this algorithm, not by the manual editing procedures, in some degree. But programs based on more complicated and accurate algorithms may lead to a nearly flawless elimination of these linear artifacts automatically.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.150-153
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• 2002

The use of the finite element method for biomechanical analysis is increasing rapidly in recent years. Since biomechanical models are usually in very complex shapes, it takes a lot of time and efforts to build reasonable finite element models. In this paper, a new tetrahedral meshing algorithm from the series of 2-D computed tomography(CT) images has been proposed. In this scheme, the planar sections of three-dimensional objects and the side surfaces between two planar sections are triangulated first, and then an advancing front algorithm is employed to construct tetrahedral elements by using basic operators. A sample finite element model for thoracic vertebra is presented.

• 한국정보과학회논문지:소프트웨어및응용
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• 제32권7호
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• pp.625-635
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• 2005

본 논문에서는 흥부 CT 영상에서 폐 부위를 효율적으로 자동 분할하기 위한 하이브리드 접근기법을 제안한다. 본 제안방법은 다음과 같은 세 단계로 구성된다 첫 번째, 2, 3차원 자동 씨앗 영역성장법과 저해상도 연결요소 레이블링을 통하여 폐와 기관지를 분할한다. 두 번째, 2차원 형태학적 연산을 반복 적용하여 폐와 기관지를 분리한 후 저해상도 연결요소 레이블링을 이용하여 폐만 분할한다. 세 번째, 영상차감 기법을 사용한 폐 영역 보정을 통해 보다 정확한 폐 영역을 얻는다. 실험에서는 5명의 환자로부터 얻은 10개의 흉부 CT 영상을 사용하여 제안방법의 정확성과 효율성을 평가한다. 제안한 자동 분할 기법의 적용 결과를 전문가에 의한 수동 분할 결과와 비교함으로써 정확성을 평가하고, 수행시간과 메모리 사용량을 분석하여 제안방법의 효율성을 평가한다. 제안한 저해상도 연결요소 레이블링을 사용했을 때 수행시간은 평균 31.4초, 최대 메모리 사용량은 평균 196.75MB가 단축된다. 본 제안방법은 혈관에 생기는 빈 공간을 막아주는 추가작업 없이 효율적으로 자동 폐 분할을 수행한다.

• 한국방사선학회논문지
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• 제13권5호
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• pp.675-681
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• 2019

근골격계 수술 전 CT 촬영 후 3차원 체적영상을 Increment별로 구현하는 과정에서 시간이 많이 소요되지 않고 데이터의 양도 많지 않은 적절한 Increment를 찾아 제안하고자 한다. 이에 본 연구에서는 손, 무릎, 발인체팬텀을 CT로 검사후, MMWP 프로그램을 사용하여 3차원 체적영상을 구현하여 재현성 평가를 하였다. 첫 실험으로는 각 Increment에 따른 세 가지 인체팬텀 별 데이터양을 분석하였다. 두번째 실험으로는 재현성평가와 실측 길이를 비교하였다. Increment에 따라 각 팬텀별로 이미지 데이터양을 분석한 결과 Increment를 0.1mm 로 설정했을 때보다 1.0mm 로 설정하였을 때 1/10 정도로 데이터양이 줄어드는 것을 확인할 수 있었다. 구현성 평가를 하였을 때 손 팬텀은 0.7mm, 무릎 팬텀과 발 팬텀은 0.6mm 부터 gap이 생성되었고 실제 팬텀과 실측 길이를 비교하였을 때 길이가 많이 차이나서 구현성이 낮아지는 것을 확인할 수 있었다. Increment가 1.0mm 에 가까울수록 이미지 수가 적고, 3D 구현 시간이 적게 소요되지만 gap이 생성되면 구현성이 급격이 낮아지는 것을 확인할 수 있었다. 따라서 영상의 gap이 생성되기 전 Increment를 알아내어 적용하는 것이 수술 전 진단을 내리기에 가장 적합하다. 본 연구를 통해 CT 촬영후 VRT Rendering을 통한 3D 영상 구현시 정확한 Increment 설정을 증명할 수 있는 지표가 되기를 기대한다.

• Clinics in Shoulder and Elbow
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• 제23권3호
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• pp.119-124
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• 2020

Background: This study was performed to compare glenoid version and inclination measured using two-dimensional (2D) images from computed tomography (CT) scans or three-dimensional (3D) reconstructed bone models. Methods: Thirty patients who had undergone conventional CT scans were included. Two orthopedic surgeons measured glenoid version and inclination three times on 2D images from CT scans (2D measurement), and two other orthopedic surgeons performed the same measurements using 3D reconstructed bone models (3D measurement). The 3D-reconstructed bone models were acquired and measured with Mimics and 3-Matics (Materialise). Results: Mean glenoid version and inclination in 2D measurements were -1.705° and 9.08°, respectively, while those in 3D measurements were 2.635° and 7.23°. The intra-observer reliability in 2D measurements was 0.605 and 0.698, respectively, while that in 3D measurements was 0.883 and 0.892. The inter-observer reliability in 2D measurements was 0.456 and 0.374, respectively, while that in 3D measurements was 0.853 and 0.845. Conclusions: The difference between 2D and 3D measurements is not due to differences in image data but to the use of different tools. However, more consistent results were obtained in 3D measurement. Therefore, 3D measurement can be a good alternative for measuring glenoid version and inclination.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제34권5호
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• pp.555-561
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• 2008

Purpose: The goal of this study was to develop a technique for creating a computerized composite maxillofacial-dental model, based on point-based surface best fit algorithm and to test its accuracy. The computerized composite maxillofacial-dental model was made by the three dimensional combination of a 3-dimensional (3D) computed tomography (CT) bone model with digital dental model. Materials and Methods: This integration procedure mainly consists of following steps : 1) a reconstruction of a virtual skull and digital dental model from CT and laser scanned dental model ; 2) an incorporation of dental model into virtual maxillofacial-dental model by point-based surface best fit algorithm; 3) an assessment of the accuracy of incorporation. To test this system, CTs and dental models from 3 volunteers with cranio-maxillofacial deformities were obtained. And the registration accuracy was determined by the root mean squared distance between the corresponding reference points in a set of 2 images. Results and Conclusions: Fusion error for the maxillofacial 3D CT model with the digital dental model ranged between 0.1 and 0.3 mm with mean of 0.2 mm. The range of errors were similar to those reported elsewhere with the fiducial markers. So this study confirmed the feasibility and accuracy of combining digital dental model and 3D CT maxillofacial model. And this technique seemed to be easier for us that its clinical applicability can good in the field of digital cranio-maxillofacial surgery.

• Restorative Dentistry and Endodontics
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• 제37권3호
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• pp.136-141
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• 2012

Objectives: The maintenance of the healthy periodontal ligament cells of the root surface of donor tooth and intimate surface contact between the donor tooth and the recipient bone are the key factors for successful tooth transplantation. In order to achieve these purposes, a duplicated donor tooth model can be utilized to reduce the extra-oral time using the computer-aided rapid prototyping (CARP) technique. Materials and Methods: Briefly, a three-dimensional digital imaging and communication in medicine (DICOM) image with the real dimensions of the donor tooth was obtained from a computed tomography (CT), and a life-sized resin tooth model was fabricated. Dimensional errors between real tooth, 3D CT image model and CARP model were calculated. And extra-oral time was recorded during the autotransplantation of the teeth. Results: The average extra-oral time was 7 min 25 sec with the range of immediate to 25 min in cases which extra-oral root canal treatments were not performed while it was 9 min 15 sec when extra-oral root canal treatments were performed. The average radiographic distance between the root surface and the alveolar bone was 1.17 mm and 1.35 mm at mesial cervix and apex; they were 0.98 mm and 1.26 mm at the distal cervix and apex. When the dimensional errors between real tooth, 3D CT image model and CARP model were measured in cadavers, the average of absolute error was 0.291 mm between real teeth and CARP model. Conclusions: These data indicate that CARP may be of value in minimizing the extra-oral time and the gap between the donor tooth and the recipient alveolar bone in tooth transplantation.