Tomographic Reconstruction of a Three-Dimensional Flow Field with Limited Interferometric Data

Cha, Dong-Jin The Society of Air-Conditioning and Refrigerating 2000 International Journal Of Air-Conditioning and Refr Vol.8 No.2

Holographic interferometric tomography can provide reconstruction of instantaneous three-dimensional gross flow fields. The technique however confronts ill-posed reconstruction problems in practical applications. Experimental data are usually limited in projection and angular scanning when a field is captured instantaneously or under the obstruction of test models and test section enclosures. An algorithm, based on a series expansion method, has been developed to improve the reconstruction under the ill-posed conditions. A three-dimensional natural convection flow around two interacting isothermal cubes is experimentally investigated. The flow can provide a challenging reconstruction problem and lend itself to accurate numerical solution for comparison. The refractive index fields at two horizontal sections of the thermal plume with and without an opaque object are reconstructed at a limited view angle of 80$\circ$. The experimental reconstructions are then compared with those from numerical calculation and thermocouple thermometry. It confirms that the technique is applicable to reconstruction of reasonably complex, three-dimensional flow fields.

집속이온빔장치와 주사전자현미경을 이용한 박막 트랜지스터 구조불량의 3차원 해석

김지수,이석열,이임수,김재열,Kim, Ji-Soo,Lee, Seok-Ryoul,Lee, Lim-Soo,Kim, Jae-Yeal 한국현미경학회 2009 Applied microscopy Vol.39 No.4

TFT-LCD의 구조불량이 발생한 박막 트랜지스터에 대해서 집속이온빔 가공장치(Dual-beam FIB/SEM)를 이용하여 연속절편법(Serial sectioning)과 일련의 연속적인 2차원 주사전자현미경 이미지를 얻었고, IMOD 소프트웨어를 통해서 3차원 구조구현(3D reconstruction) 연구를 하였다. 3차원 구조구현 결과, Gate막과 Data막이 접합되어 있는 불량이 관찰되었다. 두 막이 접합되어서 ON/OFF 역할을 하는 Gate의 기능이 상실되었고, Data신호는 Drain을 통해서 투명전극에 전류를 공급하여 계속 빛나는 선 불량(line defect)이 발생한 것으로 판단된다. 이 논문의 결과인 집속이온빔 가공장치(Dual-Beam FIB/SEM)를 이용한 3차원 구조구현 연구와 연속절편법, 주사전자현미경 이미지작업, 이미지 프로세싱에 대한 결과는 향후 연구의 기초자료로 활용될 수 있을 것으로 판단된다. In this paper we have constructed three dimensional images and examined structural failure on thin film transistor (TFT) liquid crystal display (LCD) by using dual-beam focused ion beam (FIB) and IMOD software. Specimen was sectioned with dual-beam focused ion beam. Series of two dimensional images were obtained by scanning electron microscopy. Three dimensional reconstruction was constructed from them by using IMOD software. The short defect between Gate layer and Data layer was found from the result of three dimensional reconstruction. That phenomena made the function of the gate lost and data signal supplied to the electrode though the Drain continuously. That signal made continuous line defect. The result of the three dimensional reconstruction, serial section, SEM imaging by using the FIB will be the foundation of the next advanced study.

3 자유도 회전 관절체에 대한 회전각도 계산 및 삼차원 복원

박지헌 한국정보기술학회 2019 한국정보기술학회논문지 Vol.17 No.3

In this paper, we propose a new method to reconstruct three-dimensional articulated body with one revolute joint using images taken with a moving camera with autofocus function. All input image scenes consist of rotating joints with different angular shapes. First, an internal and external parameters of a camera are calculated using the reconstruct technique using the feature points on a fixed environmental object. Thereafter, a three-dimensional restoration operation is performed on the fixed part as well as on the rotating joint part. Using the feature points of the joint, we calculate the angle of rotation and center of rotation of a joint for each input scene. Using the calculated rotation angle and center of rotation, we reconstruct the three-dimensional volume of the rotating joint. The basic concept for reconstructing three-dimensional joints is that a separate three-dimensional reconstruction is performed for each joint, and an fixed relationship is established between each joint and the camera. The rotational angle calculation results for a rotating joint were compared with the correct angle. The angular computation error was small so that 3D reconstruction was possible. 본 논문에서는 자동 초점 기능이 있는 움직이는 카메라로 촬영한 이미지를 사용하여 1개의 회전 관절을 가진 관절체를 3차원으로 복원하는 새로운 방법을 제시한다. 모든 입력 이미지 장면은 다른 각도의 형상을 가진 회전 관절체로 구성된다. 먼저 고정 된 환경 물체에 존재하는 특징점을 사용하여 카메라의 내부 및 외부 매개 변수를 최적화 기법을 사용하여 계산한다. 이후 고정된 부위와 회전하는 관절체의 부위에 대해 삼차원 복원 작업을 수행한다. 회전 관절체 부위의 특징점들을 사용하여 각 입력 장면에 대해 관절체의 회전각도와 회전 중심을 계산한다. 계산된 회전각과 회전 중심을 사용하여 회전 관절체에 대한 3차원 체적을 복원한다. 삼차원 관절체 복원을 위한 기본 개념은 각각의 관절에 대하여 별도의 삼차원 복원을 실시하고, 또한 각각의 관절과 카메라 사이에 촬영으로 인해 불변의 관계가 형성된다는 점이다. 하나의 회전형 관절체에 대한 회전각도 계산 결과는 정답 각도와 비교되었고 각도 계산 오차가 작아서 삼차원 복원이 가능하다 .

컴퓨터 그래픽을 이용하여 삼차원적으로 재구성한 청각경로

강윤규 大韓再活醫學會 1998 Annals of Rehabilitation Medicine Vol.22 No.5

3차원 영상분석을 활용한 석탑의 해체와 재조립 : 심곡사칠층석탑 사례 연구

최희수,이찬희,한성희,이성민 한국문화재보존과학회 2016 보존과학회지 Vol.32 No.4

이 연구는 심곡사칠층석탑의 해체와 재조립에 3차원 영상분석 기법을 적용하여 원형에 가깝게 보수한 기술적 사례로써 의미가 있다. 석탑의 해체와 재조립 과정에서 전체적인 변형상태와 변위를 분석하였으며 구조적 안정성 검토를 통하여 재조립에 따른 변형을 최소화하였다. 또한 석탑의 원위치도 재검토하여 보수에 적용하였다. 재조립에 앞서 오염된 석재의 표면은 과학적 표면세정을 통해 이끼류와 지의류 등을 제거하였고, 석탑의 지반은 강회를 이용한 판축과 유사한 형식으로 다짐하여 보강하였다. 이 결과는 석탑의 해체와 재조립 과정에 중요한 자료로 활용될 수 있을 것이다. This research was a technical case study for the authentic restoration of the seven-storied Simgoksa stone pagoda after disassembly and reconstruction using three-dimensional image analysis. During disassembly and reconstruction, the pagoda's properties were analyzed in terms of the overall modification and displacement of the pagoda. Distortion was minimized by ensuring structural stability during the reconstruction process. Also, the original site of the pagoda was examined in order to utilize it fully during rebuilding. Before reconstruction of the pagoda, moss and lichen on the stone surfaces were removed by scientific surface cleaning. The foundation of the pagoda was reinforced with rammed earth than was similar to the original foundation using a mixture of soil and quicklime. The results are expected to provide valuable data for the reconstruction of other stone pagodas.

Three-Dimensional Reconstruction Computed Tomography Evaluation of the Tunnel Location and Angle in Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction: A Comparison of the Anteromedial Portal and Outside-in Techniques

( Kang-il Kim ),( Sang Hak Lee ),( Chanil Bae ),( Sung Hae Bae ) 대한슬관절학회 2017 대한슬관절학회지 Vol.29 No.1

Purpose: The purpose of this study was to compare the geometry and position of the femoral tunnel between the anteromedial portal (AMP) and outside-in (OI) techniques after anatomic single-bundle anterior cruciate ligament (ACL) reconstruction. Materials and Methods: We evaluated 82 patients undergoing single-bundle ACL reconstruction with hamstring autografts using either the AMP (n=40) or OI (n=42) technique. The locations of the tunnel apertures were assessed by postoperative 3-dimensional computed tomography imaging. The femoral graft bending angle, femoral tunnel aperture shape, femoral tunnel length, and posterior wall breakage were also measured. Results: The mean femoral tunnel position parallel to the Blumensaat line was more caudally positioned in the AMP group than in the OI group (p=0.025) The mean femoral graft angle in the OI group (99.6°±7.1°) was significantly more acute than that of the AMP group (108.9°±10.2°, p<0.001). The mean height/width ratio of the AMP group (1.21±0.20) was significantly more ellipsoidal than that of the OI group (1.07±0.09, p<0.001). Conclusions: The mean femoral tunnel position was significantly shallower in the AMP technique than in the OI technique. The OI technique might be more disadvantageous than the AMP technique in terms of the more acute bending angle.

보행자의 2차원 영상으로부터 3차원 자세 복원 연구

이중빈(Jungbin Lee),구승범(Seungbum Koo) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12

Gait is important motion that contains biological information. Individual gait pattern is determined by subject’s habit, body type and diseases. Motion capture system is used to measure joint motion but is limited to capture within a laboratory. Optical camera is portable, simple to configure and take photographs of movement of a person, while it produces only two-dimensional information. The purpose of the study was to estimate three-dimensional pose and joint angles from two-dimensional sequential images of walking motion. Three-dimensional trajectories of body markers from three subjects and five motions were pooled together and their mean pose and principal components were obtained. One of the motion capture data was projected to a camera plane by assuming a fixed camera position. Optimizations to calculate a weight matrix of the principal components of body pose were performed with and without a constraint of body segment length to match the plane projected marker positions. Mean three-dimensional errors (standard deviation) of estimated marker trajectory were calculated using measured marker trajectory. Three-dimensional errors with and without constraint of body segment length were 3.44(±0.65) cm and 3.25(±0.80) cm, respectively. Two-dimensional errors (standard deviation) of projected marker to image were calculated using original image. Two-dimensional errors were 1.63(±0.41) pixel and 1.40(±0.38) pixel respectively. Flexion and extension angle of knee was estimated as RMS error, 2.54degree and 2.28degree respectively.

Three-dimensional Reconstruction of the Knee for Ligament Reconstruction

Kim, Sung-Hwan,Ha, Seung-Joo 국제컴퓨터가상수술학회 2014 Journal of International Society for Simulation Su Vol.1 No.1

As computer technology develops and this is applied to medical image field, three dimensional image reconstruction technology using computer simulation is utilized in various categories that include anatomical study and biomechanics study of human body. Especially orthopedic surgeons are able to investigate biomechanical function and be provided information for operations with this technology in terms of ligament reconstruction of knee. And this technology can be utilized in preparing preoperative planning and instructions and training. This review is about three dimensional image reconstruction technology which is utilized in ligament reconstruction of knee.

Free-view Pixels of Elemental Image Rearrangement Technique (FPERT)

Lee, Jaehoon,Cho, Myungjin,Inoue, Kotaro,Tashiro, Masaharu,Lee, Min-Chul The Korea Institute of Information and Commucation 2019 Journal of information and communication convergen Vol.17 No.1

In this paper, we propose a new free-view three-dimensional (3D) computational reconstruction of integral imaging to improve the visual quality of reconstructed 3D images when low-resolution elemental images are used. In a conventional free-view reconstruction, the visual quality of the reconstructed 3D images is insufficient to provide 3D information to applications because of the shift and sum process. In addition, its processing speed is slow. To solve these problems, our proposed method uses a pixel rearrangement technique (PERT) with locally selective elemental images. In general, PERT can reconstruct 3D images with a high visual quality at a fast processing speed. However, PERT cannot provide a free-view reconstruction. Therefore, using our proposed method, free-view reconstructed 3D images with high visual qualities can be generated when low-resolution elemental images are used. To show the feasibility of our proposed method, we applied it to optical experiments.

3D Printed Titanium Implant for the Skull Reconstruction: A Preliminary Case Study

Choi, Jong-Woo,Ahn, Jae-Sung 국제컴퓨터가상수술학회 2014 Journal of International Society for Simulation Su Vol.1 No.2

The skull defect can be made after the trauma, oncologic problems or neurosurgery. The skull reconstruction has been the challenging issue in craniofacial fields for a long time. So far the skull reconstruction with autogenous bone would be the standard. Although the autogenous bone would be the ideal one for skull reconstruction, donor site morbidity would be the inevitable problem in many cases. Meanwhile various types of allogenic and alloplastic materials have been also used. However, skull reconstruction with many alloplastic material have produced no less complications including infection, exposure, and delayed wound healing. Because the 3D printing technique evolved so fast that 3D printed titanium implant were possible recently. The aim of this trial is to try to restore the original skull anatomy as possible using the 3D printed titanium implant, based on the mirrored three dimensional CT images based on the computer simulation. Preoperative computed tomography (CT) data were processed for the patient and a rapid prototyping (RP) model was produced. At the same time, the uninjured side was mirrored and superimposed onto the traumatized side, to create a mirror-image of the RP model. And we fabricated Titanium implant to reconstruct three-dimensional orbital structure in advance, using the 3D printer. This prefabricated Titanium-implant was then inserted onto the defected skull and fixed. Three dimensional printing technique of titanium material based on the computer simulation turned out to be very successful in this patient. Individualized approach for each patient could be an ideal way to manage the traumatic patients in near future.