• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.956-959
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• 2005

The overall goal of this thesis is to develop a new algorithm based on the octree model for geometric and mechanistic milling operation at the same time. Most commercial machining simulators are based on the Z map model, which has several limitations in terms of achieving a high level of precision in five-axis machining simulation. Octree representation being a three-dimensional (3D) decomposition method, an octree-based algorithm is expected to be able to overcome such limitations. With the octree model, storage requirement is reduced. Moreover, recursive subdivision is processed in the boundaries, which reduces useless computations. To achieve a high level of accuracy, fast computation time and less memory consumption, the advanced octree model is suggested. By adopting the supersampling technique of computer graphics, the accuracy can be significantly improved at approximately equal computation time. The proposed algorithm can verify the NC machining process and estimate the material removal volume at the same time.

• Journal of the Korean Data and Information Science Society
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• v.28 no.6
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• pp.1313-1325
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• 2017

Economic statistics such as GDP, consumer prices, balance of payments, and unemployment rates are regularly measured over time. One of the best way to understand economic statistics is to visualize economic statistics as a picture. This makes it easier to grasp patterns of economic statistics and to communicate with users. The web technologies and the visualization tools make it possible to create dynamic and interactive visualization of economic statistics. Statistics Korea and the Bank of Korea provide various data visualization relating to official statistics such as infographics and dynamic charts. This paper presents an overview of visualization of Statistics Korea and the Bank of Korea. It also discusses a future direction to explore the visualization of Korean economic statistics.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.715-718
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• 2014

맵리듀스(MapReduce)는 대용량 데이터의 병렬 처리에 사용되는 프로그래밍 모델이다. 데이터 큐브(data cube)는 대용량 데이터의 다차원 분석에 널리 사용되는 연산자로서, 주어진 차원 애트리뷰트들의 모든 가능한 조합에 대한 group-by 를 계산한다. 차원 애트리뷰트가 n 개일 때, 데이터 큐브는 총 $2^n$ 개의 group-by 를 계산한다. 본 논문은 맵리듀스 환경에서 데이터 큐브를 효율적으로 계산하는 방법을 제안한다. 제안 방법은 $2^n$ 개의 group-by 를 분할하고 이들을 ${\lceil}n/2{\rceil}$개의 맵리듀스 잡(job)을 통해 단계적으로 계산한다. 제안 방법은 각 맵리듀스 잡에서 맵 함수가 출력하는 중간결과의 크기를 최소화함으로써 총 계산 비용을 크게 줄인다. 실험을 통해 제안 방법은 기존 방법에 비해 데이터 큐브를 더 빠르게 계산함을 보인다.

• Journal of Broadcast Engineering
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• v.9 no.3
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• pp.196-206
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• 2004

This paper presents an efficient joint disparity-motion estimation algorithm for stereo sequence CODEC. Disparity vectors are estimated by the left and right motion vectors and previous disparity vectors for every frame. In order to obtain more accurate disparity vectors. we include a spatial prediction Process after the feint estimation. From joint estimation and spatial prediction, we can obtain accurate disparity vectors and then Increase coding efficiency. Finally, we proposed the backward quadtree decomposition. which helps the encoder to have a more detailed disparity vector map without transmitting additional coding bits for quadtree information. We confirmed superior performance of the proposed method through computer simulation.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.4
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• pp.200-214
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• 2014

Technology planning is becoming increasingly important with the rapid development and decline of technology. Technology roadmapping is a tool used to select whether the specific technique of technology planning should pursue which technology and in which time. This technology is important to secure the uncertain future since it will provide a method that is able to share the goals and strategies between organizations. Therefore, technology tree in the planning stage of the problem would be a very useful tool. In this study, both domestic and international technology tree application cases were analyzed to be able to derive a plan for ensuring that the research performed and the requirements are met for the future development and implementation of a convergence portal system. The six major systems that aim at water hazard information platform are basic information providing system, analysis information providing system, water disaster theme providing system, national disaster information system, water disaster augmented reality system and open information platform system. General standardized core technologies corresponding to the needed functions in each target system are derived through brainstorming, and classified according to the technology field to derive the technology tree.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10b
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• pp.529-531
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• 2004

웹 상에는 많은 자원들과 정보들이 존재한다. XML은 이러한 자원들과 정보들을 구조화하기 위해서 개발되었다. XTM(XML Topic Maps)은 XML의 형태로 자원들과 정보들에 의미를 부여할 수 있는 언어이다. XTM은 Topic과 Association을 이용해서 자원들과 정보들이 가진 의미를 표현한다 XTM상에서 나타나는 Topic과 Association은 매우 거대하고 다양하기 때문에 모든 Topic과 Association을 한꺼번에 표현하기 어렵다 또한, 사용자가 수백만개의 Topic과 Association에서 원하는 Topic과 Association을 찾기 어렵다. 따라서 이러한 문제점을 해결하기 위해서 다양한 시각화 방법이 연구되었다. 현재 Topic Maps을 표현할 때 트리, 그래프, 맵 등 하나의 구조를 이용해서 표현한다. 하지만 추상화정도에 따라 시각화 방법은 장ㆍ단점을 지닌다. 본 논문에서는 웹 상의 자원, 정보들과 의미 사이에 여러 계층이 존재하는 다층적 시각화를 제안한다. 각 계층은 독립적인 표현구조로 나타내어 추상화정도에 따라 최적화된 구조를 사용한다. 사용자는 자신이 원하는 Topic과 Association을 점진적 접근을 통해서 원하는 Topic과 Association을 검색할 수 있다. 또한 Topic이 Association의 member처럼 사용되는 경우, 시각적으로 Topic이 표현되면 Topic은 연결된 Association과 직접적인 연결을 갖는다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.422-425
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• 2004

This paper develops an octree-based algorithm for machining simulation. Most commercial machining simulators are based on the Z map model, which has several limitations in terms of achieving a high level of precision in five-axis machining simulation. Octree representation being a three-dimensional (3D) decomposition method, an octree-based algorithm is expected to be able to overcome such limitations. With the octree model, storage requirement is reduced. Moreover, recursive subdivision is processed in the boundaries, which reduces useless computations. The supersampling method is the most common form of antialiasing and is typically used with polygon mesh rendering in computer graphics. The supersampling technique is being used to advance the efficiency of the octree algorithm..

• Journal of the Korea Computer Graphics Society
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• v.9 no.4
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• pp.1-7
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• 2003

본 논문에서는 GPU와 스텐실 버퍼(stencil buffer) 및 깊이 버퍼(depth buffer)를 이용하여 가려진 픽셀들을 렌더링 단계 이전에 건너뛰는(skipping) 방법을 제시하고자 한다. 그래픽 카드에 기본적으로 제공되는 기능인 깊이 및 스텐실 버퍼 검사(depth & stencil buffer test)를 이용하여 이진 차폐 맵(binary occlusion map)을 만들고 이를 재사용하여 가려지는 부분의 픽셀들을 효과적으로 건너뛰게 하는 방법이다. 전체 볼륨 데이터는 팔진트리(octree) 구조를 가진 서브볼륨들로 나뉘어 저장되며 시점에 가까운 서브볼륨부터 렌더링에 사용된다. 서브볼륨들을 차례로 렌더링하면서 차폐 맵을 갱신하게 하면, 멀리 있는 서브볼륨들을 렌더링할 때 이미 가려진 픽셀들을 렌더링에서 제외할 수 있다.

• Korean Journal of Computational Design and Engineering
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• v.10 no.2
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• pp.107-113
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• 2005

Octree-based algorithm is developed for machining simulation. Most of commercial machining simulators are based on Z map model, which have several limitations to get a high precision in 5 axis machining simulation. Octree representation is three dimensional decomposition method. So it is expected that these limitations be overcome by using octree based algorithm. By using the octree model, storage requirement is reduced. And also recursive subdivision was processed in the boundaries, which reduces useless computation. The supersampling method is the most common form of the anti-aliasing and usually used with polygon mesh rendering in computer graphics. Supersampling technique is applied for advancing its efficiency of the octree algorithm.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.789-791
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• 2016

수동 금속 연마과정의 효율성을 향상시키기 위한 자동 시편 연마 시스템들이 개발되었으나 기존 시스템들은 시스템 내부 데이터 처리를 비-트리 인덱스를 이용하기 때문에 데이터 엑세스 효율성이 떨어지며 다수의 기기가 접속할 경우 저장 공간의 낭비가 발생한다는 문제점이 있다. 따라서 본 논문에서는 조인 결과에 대한 인덱스를 생성하고 컬럼 값 분포도가 낮은 데이터에 대한 액세스 효율성이 높은 비트캡 인덱스를 비트리 구조에 삽입하여 시편 연마기 데이터를 제공하는 시스템을 제안한다.