• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.2
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• pp.191-201
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• 2010

This paper presents a new global optimization algorithm based on the branch-and-bound principle using Bspline approximation techniques. It describes the algorithmic components and details on their implementation. The key components include the subdivision of a design space into mutually disjoint subspaces and the bound calculation of the subspaces, which are all established by a real-valued B-spline volume model. The proposed approach was demonstrated with various test problems to reveal computational performances such as the solution accuracy, number of function evaluations, running time, memory usage, and algorithm convergence. The results showed that the proposed algorithm is complete without using heuristics and has a good possibility for application in large-scale NP-hard optimization.

• Journal of Korea Multimedia Society
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• v.16 no.1
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• pp.29-41
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• 2013

The digital camera is impossible to preserve the appearance of a scene containing high dynamic range due to a limitations of the sensing hardware. The Retinex was proposed on the purpose to solve these problems. While the Retinex enhances visibility and color constancy, it sometimes suffers from color distortion, halo effect and reduced global contrast. This paper presents an advanced Retinex algorithm working on the YCbCr color coordinate to reduce the processing time and to improve the global contrast and color. Simulation results show that our algorithm significantly reduces the total processing time, and provide the superior result image by improving the global contrast and color consistency as well as by reducing the halo effect around the boundaries.

• Journal of Korea Multimedia Society
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• v.16 no.7
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• pp.829-840
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• 2013

In this paper, we propose a new lung segmentation method for chest x-ray images which can take both global and local properties into account. Firstly, the initial lung segmentation is computed by applying the active shape model (ASM) which keeps the shape of deformable model from the pre-learned model and searches the image boundaries. At the second segmentation stage, we also applied the localizing region-based active contour model (LRACM) for correcting various regional errors in the initial segmentation. Finally, to measure the similarities, we calculated the Dice coefficient of the segmented area using each semiautomatic method with the result of the manually segmented area by a radiologist. The comparison experiments were performed using 5 lung x-ray images. In our experiment, the Dice coefficient with manually segmented area was $95.33%{\pm}0.93%$ for the proposed method. Effective segmentation methods will be essential for the development of computer-aided diagnosis systems for a more accurate early diagnosis and prognosis regarding lung cancer in chest x-ray images.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2100-2103
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• 2003

기존의 객체 추출 및 추적 기법은 외형 변화가 없는 객체를 대상으로 하거나 배경이 고정된 영상만을 고려하였다 본 논문에서는 영역의 색상과 움직임 정보, 그리고 인접한 영역의 상관 관계를 고려한 Markov Random Field (MRF) 모델을 제안한다. MRF 모델은 영상의 시간적 공간적 상관성을 기반으로 최적의 레이블 셋을 계산함으로써 보다 정확하게 객체를 추출 및 추적할 수 있다. 또한, 블록 기반 움직임 추출 알고리즘인 Diamond Search (DS)를 분할된 영역에 적용하여 빠르게 영역의 움직임과 전역 움직임을 추정하였다. 실험 결과 제안한 방법이 객체의 외형 변화와 카메라 움직임이 있는 동영상에서 빠른 속도로 정확하게 객체를 추출 및 추적하는 것을 확인하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04b
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• pp.178-180
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• 2000

분산되어 있는 이질형 데이터베이스 시스템들의 자율성을 보장하고, 효율적으로 정보를 공유 및 교환하기 위한 멀티 데이터베이스 시스템에 대한 연구가 진행되고 있다. 그러나 기존의 멀티 데이터베이스 시스템은 새로운 데이터베이스를 추가하거나 제거하는 경우, 관리 시스템을 정적으로 재구성해야 한다는 문제점이 있다. 본 논문에서는 지니 기술을 기반으로 멀티 데이터베이스 관리 시스템 모델을 제안하였다. 제안하는 모델은 지니 기술의 Plug&Work 개념을 이용하여 네트워크에 연결된 데이터베이스 시스템들의 연결 변화를 동적으로 감지함으로써, 기존의 멀티 데이터베이스 시스템의 문제점을 제거할 수 있다. 또한 본 논문에서 제안하는 멀티 데이터베이스 관리 시스템은 지역 tm키마를 동적으로 통합함으로써 전역 스키마를 관리한다.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10b
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• pp.90-92
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• 1998

본 논문에서는 다수의 데이터베이스에 의해서 관리되는 데이터를 공유하기 위한 시스템관련 연구를 분석 및 소개하고, 본 연구에서 구현 중인 분산 이질 데이터베이스 환경을 위한 데이터베이스 공유 시스템의 구조, 운용 시나리오 및 구현 환경에 대해서 기술한다. 제안된 시스템은 스키마 통합 및 전역 질의 방식을 배제하면서 사용자가 데이터베이스를 고유할 수 있도록 뷰 객체모델에 기초를 둔 wrapper-공유 메니저 통합 구조로 구성되었으며, 인터넷 및 인트라넷 환경에 적합하도록 CORBA와 Java를 활용한 ObjectWeb의 개념에 기반을 두고 있다.

• The KIPS Transactions:PartA
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• v.14A no.7
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• pp.435-442
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• 2007

This paper is concerned with the mesh segmentation problem that can be applied to diverse applications such as texture mapping, simplification, morphing, compression, and shape matching for 3D mesh models. The mesh segmentation is the process of dividing a given mesh into the disjoint set of sub-meshes. We propose a method for segmenting meshes by simultaneously reflecting global and local geometric characteristics of the meshes. First, we extract sharp vertices over mesh vertices by interpreting the curvatures and convexity of a given mesh, which are respectively contained in the local and global geometric characteristics of the mesh. Next, we partition the sharp vertices into the $\kappa$ number of clusters by adopting the $\kappa$-means clustering method [29] based on the Euclidean distances between all pairs of the sharp vertices. Other vertices excluding the sharp vertices are merged into the nearest clusters by Euclidean distances. Also we implement the proposed method and visualize its experimental results on several 3D mesh models.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.5
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• pp.626-630
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• 2010

Since the paper plagiarism has become one of important social issues, it is necessary to develop system for measuring the similarity between papers. The speed and accuracy of the system are very important features. So many researchers are studying the features. In this paper, we propose a preprocessing method using 'Global Dictionary' model to enhance performance of the system. The global dictionary includes information of all words in the document repository. The system uses the model to find similar papers with low computing time. Finally our experiment showed that a set of more than 20,000 documents could be reduced to about 50 documents drastically by our filtering techniques, which proves the excellence of our system.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.1
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• pp.60-65
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• 2008

In this paper, we concern the stability of smart space by using the robust digital controller. The proposed methodologies are based on the intelligent digital redesign (IDR). More precisely, we represent the nonlinear and uncertain analog system as the Takaki-Sugeno (T-S) fuzzy model. Then the IDR problem can be reduced to find the digital gains minimizing the norm distance between the closed-loop states of the analog and digital control. Its constructive conditions are expressed as the linear matrix inequalities (LMIs). At last, a numerical example, HVAC system, is demonstrated to visualize the feasibility of the proposed methodology.

• Journal of KIISE:Software and Applications
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• v.29 no.7
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• pp.425-435
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• 2002

This paper introduces a macroblock-based rate control algorithm using the neural classifier based in Self Organization feature Maps (SOFM). In contrast to the conventional rate control methods based on the mathematical rate distortion (RD) model and the feedback regression, proposed method can actively adapt to the rapid-varying image characteristics by establishing the global model for bitrate control and by using the SOFM based neural classifier to manage that model. Proposed rate control algorithm has 0.2 dB ~ 0.6 dB better performances than MPEG-4 macroblock-based rate control algorithm by evaluating with the encoded Peak Signal to Noise Ratios while maintaining similar overall computational complexity.