• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 춘계학술대회
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• pp.133-136
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• 2012

본 논문은 무안경 3D 디스플레이 제품의 품질을 향상시키기 위한 여러 가지 효과적인 방법을 구축하는데 목적을 두었다. 무안경 제품은 기존의 안경 방식에 비하여 3D의 depth 화질 품질이 떨어졌고, 특정 거리, 위치에서만 볼 수 있는 단점이 있어, 이를 보완하고자 Head Tracking 기술 및 영상 배치알고리즘 등 여러 가지 기술을 적용하여 기존 system의 단점을 보완하였다. 본 논문은 3D 무안경 구현 방식 중 Parallax Barrier의 3D 품질 향상을 위한 Head Tracking을 통한 사용자의 위치 파악, 영상의 재배치 기술 및 Crosstalk 개선 방법에 대해 보고합니다.

• 한국의상디자인학회지
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• 제17권2호
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• pp.223-237
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• 2015

This study is to compare the pattern making methods of men's jeans and to analyze sizes of parts while also evaluating the appearance and fit according to a 3D virtual garment simulation. Five types of patterns are selected for the analysis. For the appearance evaluation, the study conducted a virtual clothing simulation, created a perspective drawing, and applied Clothing pressure to each test outfit. First, according to the pattern comparisons, A and D had the shortest crotch length, while B had the longest; B had the narrowest crotch width, while C had the widest; C had the greatest waist circumference, and B had the smallest; C had the greatest knee and hem circumference, while E had the smallest. Second, according to the appearance evaluation, E pants had the highest rating overall for the waist, crotch, knee, and hem comfort; A pants had the highest rating for the yoke line end and placement; and C pants had the highest rating for the side seam line. According to the correlation analysis, ease of the waist, hips, hem and thighs were important factors (in that order) in determining the overall appearance of the jean pants.

• Computers and Concrete
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• 제5권3호
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• pp.175-194
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• 2008

Increasingly numerical (finite element) modeling of concrete hinges on our ability to develop a representative volume element with all its heterogeneity properly discretized. Yet, despite all the sophistication of the ensuing numerical models, the initial discretization has been for the most part simplistic. Whenever the heterogeneity of the concrete is to be accounted for, a mesh is often manually crafted through the arbitrary inclusion of the particles (aggregates and/or voids) in an ad-hoc manner. This paper develops a mathematical strategy to precisely address this limitation. Algorithms for the random generation and placement of elliptical (2D) or ellipsoid (3D) inclusions, with possibly radiating cracks, in a virtual concrete model are presented. Collision detection algorithms are extensively used.

• 한국물환경학회지
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• 제22권3호
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• pp.557-565
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• 2006

Proper operation of clarifier partly depends on outlet conditions. Effluent has to be uniformly withdrawn to prevent scouring of settled sludge and carry over of settling sludge from the clarifier. In this paper, 3-D numerical model was employed to analyze the flow and settling performance of the rectangular clarifier. There were two simulation conditions of which in the same clarifier, the first one was assumed to have a 11.5 meter weir length and the second has 8.5 meters. Shape, location and placement of the weir structure were different, but both of those outlets meet weir loading design criteria. Simulation results indicate that clarifier with longer weir generally gave strong and unstable currents at the mid-stream where the weir starts while in the clarifier with short and relatively simple weir, uniform and stable flow was observed in most parts of the settling zone, and especially at the weir region. These flow conditions affected settling performance. Effulent SS concentration from clarifier equipped with the long and complicated placement of weir was 24.5 mg/L, but 7.0 mg/L from the clarfieir having short weir length. From this study, it can be concluded that as reported from other studies, weir loading does not guarantee settling performance and 3-D numerical model can be a useful tool for determining and validating outlet structure.

• 한국도서관정보학회지
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• 제53권1호
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• pp.171-190
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• 2022

이 연구의 목적은 도서관학 5법칙을 통하여 초등학교 도서관 운영의 현황을 살펴보고 그 개선방안을 제시하는 것이다. 이를 위해 연구의 범위를 부산지역으로 하여 초등학교 도서관 304곳의 운영 현황을 분석하였고, 심층조사를 위하여 부산의 D초등학교 도서관을 사례로 살펴보았다. 부산지역 초등학교 도서관의 운영 현황은 2016~2021년 동안의 도서관 보유, 사서교사 배치, 장서, 연간 이용, 예산, 좌석 등으로 구분하여 분석하였다. 분석 결과, 특히 정규직 사서교사 배치율이 10.5%에 불과해 인력 부족 문제가 심각함이 드러났다. 사례연구에서는 랑가나단의 도서관학 5법칙 중 제1법칙과 제3법칙을 중심으로 부산 D초등학교 도서관 운영 현황을 조사하였다. 제1법칙에서는 열람방식, 입지, 이용시간, 가구, 직원의 측면으로 나누어 조사하였고, 제3법칙에서는 서가배열, 목록, 확장봉사, 도서선택 측면으로 나누어 조사하였다. 특히 한 학기 한 권 읽기용 도서로 50권 이상 복본이 있는 도서가 전체 장서의 4.8%를 차지하여 불균형한 장서 구성의 문제를 보였다. 연구의 결과, 개선방안으로 '사서교사 배치 확대', '리모델링을 통한 독서환경 구축', '균형 잡힌 장서개발'을 제시하였다.

• Journal of Communications and Networks
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• 제11권1호
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• pp.57-71
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• 2009

Networking together hundreds or thousands of cheap sensor nodes allows users to accurately monitor a remote environment by intelligently combining the data from the individual nodes. As sensor nodes are typically battery operated, it is important to efficiently use the limited energy of the nodes to extend the lifetime of the wireless sensor network (WSN). One of the fundamental issues in WSNs is the coverage problem. In this paper, the border coverage problem in WSNs is rigorously analyzed. Most existing results related to the coverage problem in wireless sensor networks focused on planar networks; however, three dimensional (3D) modeling of the sensor network would reflect more accurately real-life situations. Unlike previous works in this area, we provide distributed algorithms that allow the selection and activation of an optimal border cover for both 2D and 3D regions of interest. We also provide self-healing algorithms as an optimization to our border coverage algorithms which allow the sensor network to adaptively reconfigure and repair itself in order to improve its own performance. Border coverage is crucial for optimizing sensor placement for intrusion detection and a number of other practical applications.

• 한국CDE학회논문집
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• 제2권3호
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• pp.195-210
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• 1997

In Rapid Prototyping process, the time required to build multiple prototype parts can be reduced by packing several parts optimally in a work volume. Interactive arrangement of the multiple parts is a tedious process and does not guarantee the optimal placement of all the parts. In this case, packing is a kind of 3-D nesting problem because parts are represented by STL files with 3-D information. 3-D nesting is well known to be a problem requiring an intense computation and an efficient algorithm to solve the problem is still under investigation. This paper proposes that packing 3-D parts can be simplified into a 2-D irregular polygon nesting problem by using the characteristic of rapid prototyping process that the process uses 2-dimensional slicing data of the parts and that slice of the STL parts are composed of polygons. Our algorithm uses no-fit-polygon (NFP) to place each slice without overlapping other slices in the same z-level. The allowable position of one part at a fixed orientation for given parts already packed can be determined by obtaining the union of all NFP's that are obtained from each slice of the part. Genetic algorithm is used to determine the order of parts to be placed and orientations of each part for the optimal packing. Optimal orientation of a part is determined while rotating it about the axis normal to the slice by finite angles and flipping upside down. This algorithm can be applied to any rapid prototyping process that does not need support structures.

• 한국정보통신학회논문지
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• 제16권8호
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• pp.1811-1816
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• 2012

본 연구에서는 흑백 마커를 사용하므로 생기는 기존 콘텐츠와 마커간의 부자연스러운 문제를 다양한 컬러 및 색상 배치에 따른 3D 물체의 증강 정도를 실험을 통하여 확인하였으며, 이를 바탕으로 모바일 기반에서 증강현실 기술지원을 하는 NyARToolkit 기반으로 유아용 학습 콘텐츠 시스템을 구현하였다. 구현한 콘텐츠에서 필요한 페이지에 컬러 마커를 삽입하므로 부자연스러운 문제를 해결할 수 있었고, 이 마커 위에 학습내용과 관련된 심화 자료를 띄우므로 집중력을 높임과 동시에 학습보조자가 원활하게 콘텐츠를 사용할 수 있었다.

• ETRI Journal
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• 제31권4호
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• pp.429-437
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• 2009

This paper proposes a novel technique for 3D scene relighting with interactive viewpoint changes. The proposed technique is based on a deep framebuffer framework for fast relighting computation which adopts image-based techniques to provide arbitrary view-changing. In the preprocessing stage, the shading parameters required for the surface shaders, such as surface color, normal, depth, ambient/diffuse/specular coefficients, and roughness, are cached into multiple deep framebuffers generated by several caching cameras which are created in an automatic manner. When the user designs the lighting setup, the relighting renderer builds a map to connect a screen pixel for the current rendering camera to the corresponding deep framebuffer pixel and then computes illumination at each pixel with the cache values taken from the deep framebuffers. All the relighting computations except the deep framebuffer pre-computation are carried out at interactive rates by the GPU.

• 대한치과교정학회지
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• 제46권4호
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• pp.189-198
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• 2016

Objective: The purpose of this study was to analyze stress distributions in the roots, periodontal ligaments (PDLs), and bones around cylindrical and tapered miniscrews inserted at different angles using a finite element analysis. Methods: We created a three-dimensional (3D) maxilla model of a dentition with extracted first premolars and used 2 types of miniscrews (tapered and cylindrical) with 1.45-mm diameters and 8-mm lengths. The miniscrews were inserted at $30^{\circ}$, $60^{\circ}$, and $90^{\circ}$ angles with respect to the bone surface. A simulated horizontal orthodontic force of 2 N was applied to the miniscrew heads. Then, the stress distributions, magnitudes during miniscrew placement, and force applications were analyzed with a 3D finite element analysis. Results: Stresses were primarily absorbed by cortical bone. Moreover, very little stress was transmitted to the roots, PDLs, and cancellous bone. During cylindrical miniscrew insertion, the maximum von Mises stress increased as insertion angle decreased. Tapered miniscrews exhibited greater maximum von Mises stress than cylindrical miniscrews. During force application, maximum von Mises stresses increased in both groups as insertion angles decreased. Conclusions: For both cylindrical and tapered miniscrew designs, placement as perpendicular to the bone surface as possible is recommended to reduce stress in the surrounding bone.