• Journal of Radiation Protection and Research
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• 제45권1호
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• pp.35-44
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• 2020

Background: Cadmium zinc telluride (CZT) is a promising material because of a high detection efficiency, good energy resolution, and operability at room temperature. However, the cost of CZT dramatically increases as its size increases. In this study, to achieve a large effective volume with relatively low cost, an array structure comprised of individual virtual Frisch-grid CZT detectors was proposed. Materials and Methods: The prototype consisted of 2 × 2 CZTs, a holder, anode and cathode printed circuit boards (PCBs), and an application-specific integrated circuit (ASIC). CZTs were used and the non-contacting shielding electrode method was applied for virtual Frisch-grid effect. An ASIC was used, and the holder and the PCBs were fabricated. In the current system, because the CZTs formed a common cathode, a total of 5 channels were assigned for data processing. Results and Discussion: An experiment using ¹³⁷Cs at room temperature was conducted for 10 minutes. Energy and timing information was acquired and the depth of interaction was calculated by the timing difference between the signals of both electrodes. Based on obtained three-dimensional position information, the energy correction was carried out, and as a result the energy spectra showed the improvements. In addition, a Compton image was reconstructed using the iterative method. Conclusion: The virtual Frisch-grid CZT detector based on the array structure was developed and the energy spectra and the Compton image were successfully acquired.

• 천문학회보
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• 제39권2호
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• pp.45.2-45.2
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• 2014

To measure the mass distribution of galaxy systems weak-lensing analysis has been widely used because it directly measures the total mass of a system regardless of its baryon content and dynamical state. However, the weak-lensing only provides a map of projected surface mass density. On the other hand, galaxy redshift surveys provide a map of the three-dimensional galaxy distribution. It thus can resolve the structures along the line of sight projected in the weak-lensing map. Therefore, the comparison of structures identified in the weak-lensing maps and in the redshift surveys is an important test of the issues limiting applications of weak-lensing to the identification of galaxy clusters. Geller et al. (2010) and Kurtz et al. (2012) compared massive clusters identified in a dense redshift survey with significant weak-lensing map convergence peaks. Both assessments of the efficiency of weak-lensing map for cluster identification did not draw a general conclusion, because the sample is so small. Thus, we additionally perform deep imaging observations of fields in a dense galaxy redshift survey that contain galaxy clusters at z~0.2-0.5, using CFHT Megacam.

• 대한두개안면성형외과학회지
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• 제21권1호
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• pp.69-72
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• 2020

Hemangioma is a benign vascular tumor that grows by endothelial cell hyperplasia. It occurs most frequently in the head and neck region. Nose reconstruction is tricky because of its unique three-dimensional structure and different tissue components. We report a case of successful reconstruction of near-total nose defect using the paramedian forehead flap combined with a nasolabial flap, immediately after excision of nasal hemangioma. A 49-year-old male patient was presented with a huge mass at the nose. Preoperative magnetic resonance imaging showed prominent vascular channels extending to the forehead and cheek. Complete resection of the mass was performed, which resulted in an eccentric defect. The right paramedian forehead flap and the left nasolabial flap were designed and transferred to the defect. Flap division was performed 1 month later. The patient is satisfied with the overall appearance and did not develop any functional deficit.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• 제25권1호
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• pp.23-34
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• 1997

Seismic tomography using the graph theoretical method of ray tracing is performed in two synthetic data sets with laterally varying velocity structures. The straight-ray tomography shows so poor results in imaging the laterally varying velocity structure that the ray-traced tomographic techniques should be used. Conventional ray tracing methods have serious drawbacks, i.e. problems of convergence and local minima, when they are applied to seismic tomography. The graph theretical method finds good approximated raypaths in rapidly varying media even in shadow zones, where shooting methods meet with convergence problems. The graph theoretical method ensures the globally minimal traveltime raypath while bending methods often cause local minima problems. Especially, the graph theoretical method is efficient in case that many sources and receivers exist, since it can find the traveltimes and corresponding raypaths to all receivers from a specific source at one time. Moreover, the algorithm of graph theoretical method is easily applicable to the ray tracing in anisotropic media, and even to the three dimensional case. Among the row-active inversion techniques, the conjugate gradient (CG) method is used because of fast convergence and high efficiency. The iterative sequence of the ray tracing by the graph theoretical method and the inversion by the CG method is an efficient and robust algorithm for seismic tomography in laterally varying velocity structures.

• 지구물리와물리탐사
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• 제4권4호
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• pp.101-109
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• 2001

다양한 지하 정보를 효율적으로 관리하고 사용자가 필요로 하는 형태의 정보를 쉽게 가공할 수 있는 공간 정보 시스템을 구축하기 위하여 시추 정보를 데이타베이스화 하였고 시추공, 광체, 터널, 채굴 공동 등의 지하 개체를 3차원으로 시각화하였다. 또한 여기서 만들어진 3차원 광체에 이용할 수 있는 분석 도구, 즉 수직 단면 생성 도구, 매장량 계산 도구 등을 제작하였다. 이 정보 시스템은 상응 GIS 소프트웨어인 ArcView의 스크립트 언어인 Avenue를 사용하여 개발하였으며, 사용자들이 실시간 질의와 개체의 다양한 조합 및 3차원 조망을 통해 지하 구조에 대한 정확한 분석 및 해석을 쉽게 그리고 신속히 할 수 있도록 하였다.

• Current Optics and Photonics
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• 제3권6호
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• pp.571-576
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• 2019

The morphological changes of anthracnose (fungus) -infected tomato seeds have been studied to identify the infection and characterize its effect. Full-field optical coherence tomography (FF-OCT) has been utilized as a nondestructive but efficient modality for visualizing the effects of fungal infection. The cross-sectional images extracted from a stack of en face FF-OCT images showed significant changes with infection in the seed structure. First of all, the seed coat disappeared with the infection. The thickness of the seed coat of a healthy seed was measured as 28.2 ㎛, with a standard deviation of 1.2 ㎛. However, for infected seeds the gap between surface and endosperm was not appreciably observed. In addition, the measurements confirmed that the dryness of seeds did not affect the internal seed structure. The reconstructed three-dimensional (3D) image revealed that the permeability of the seed coat, which plays the vital role of protecting the seed, is also affected by the infection. These results suggest that FF-OCT has good potential for the identification of fungus-infected tomato seeds, and for many other tasks in agriculture.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제40권
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• pp.2.1-2.7
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• 2018

With the development of computer-aided design/computer-aided manufacturing (CAD/CAM) technology, it has been possible to reconstruct the cranio-maxillofacial defect with more accurate preoperative planning, precise patient-specific implants (PSIs), and shorter operation times. The manufacturing processes include subtractive manufacturing and additive manufacturing and should be selected in consideration of the material type, available technology, post-processing, accuracy, lead time, properties, and surface quality. Materials such as titanium, polyethylene, polyetheretherketone (PEEK), hydroxyapatite (HA), poly-DL-lactic acid (PDLLA), polylactide-co-glycolide acid (PLGA), and calcium phosphate are used. Design methods for the reconstruction of cranio-maxillofacial defects include the use of a pre-operative model printed with pre-operative data, printing a cutting guide or template after virtual surgery, a model after virtual surgery printed with reconstructed data using a mirror image, and manufacturing PSIs by directly obtaining PSI data after reconstruction using a mirror image. By selecting the appropriate design method, manufacturing process, and implant material according to the case, it is possible to obtain a more accurate surgical procedure, reduced operation time, the prevention of various complications that can occur using the traditional method, and predictive results compared to the traditional method.

• 한국임상수의학회지
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• 제24권3호
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• pp.461-466
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• 2007

Two dogs were admitted with a history of anorexia, ataxia, shivering, lethargy, hypersalivation and seizure. Patients were suspected for portosystemic shunts on the basis of clinical signs, increased hepatic serum profiles on the blood test, microhepatica on plain abdominal radiographs, and an abnormally dilated and tortuous vessel on abdominal ultrasonographs. To diagnose PSS and to further evaluate type, shape, and location of shunt and hepatic vasculatures, the computed tomography (CT) angiography for portal and systemic circulation was performed. The shape, location and pathway of extrahepatic single shunt were confirmed in two dogs. Dual phases (the arterial phase and the venous phase) CT angiography and reformatted and three-dimensional images offered good understanding of PSS and planning surgical treatment.

• Journal of information and communication convergence engineering
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• 제17권2호
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• pp.91-96
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• 2019

In this study, a system to increase the expressiveness of existing standard terminology using three-dimensional (3D) data is designed. We analyze the existing medical terminology system by searching the reference literature and perform an expert group focus survey. A human body image is generated using a 3D modeling tool. Then, the anatomical position of the human body is mapped to the 3D coordinates' identification (ID) and metadata. We define the term to represent the 3D human body position in a total of 12 categories, including semantic terminology entity and semantic disorder. The Blender and 3ds Max programs are used to create the 3D model from medical imaging data. The generated 3D human body model is expressed by the ID of the coordinate type (x, y, and z axes) based on the anatomical position and mapped to the semantic entity including the meaning. We propose a system of standard terminology enabling integration and utilization of the 3D human body model, coordinates (ID), and metadata. In the future, through cooperation with the Electronic Health Record system, we will contribute to clinical research to generate higher-quality big data.

• 대한수의학회지
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• 제59권2호
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• pp.55-58
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• 2019

This study was performed to examine the visualization and anatomical variants of the hepatic artery with dual-phase computed tomography (CT) angiography and three-dimensional volume rendering imaging analysis in clinically normal dogs. Seven healthy beagle dogs were enrolled and underwent dual CT angiography. Arterial phase images could be obtained with multi-detector CT angiography using the fixed-scan method in these dogs. Contrast enhancement of the hepatic parenchyma was quite minimal because of the unique blood supply system of the liver. In most dogs, the main hepatic arterial branches were the right lateral branch, left branch, and right medial branch. Although hepatic arterial variation appears to be common in dogs, only one dog in this study had the caudate lobar branch as the first branch of the hepatic artery. Further study on a larger number of dogs with CT images will be needed to identify and classify the pattern of hepatic arterial variations.