• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.773-777
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• 2011

본 논문에서는 국부적으로 비선형 거동을 보이는 고전적인 $J_2$ 소성흐름 이론에 근거한 탄소성 문제의 해를 효율적으로 구하기 위해 전체-국부 확장함수를 지닌 일반유한요소법을 제안한다. 제안된 기법은 비선형 거동을 보이는 영역을 포함하는 국부 문제의 비선형 해를 구하고 이를 일반유한요소법의 단위 오목 분할의 개념을 통해 전체 문제의 해 공간을 확장하는데 이용한다. 이는 적은 계산량으로 복잡한 탄소성문제의 정확한 해를 얻는 것을 가능하게 하며 기법의 강건성과 정확성을 입증하기 위한 수치해석 예제가 다루어진다.

• Journal of KIISE:Software and Applications
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• v.31 no.12
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• pp.1684-1690
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• 2004

This paper presents a method for classifier selection that uses distribution information of the training samples in a small region surrounding a sample. The conventional DCS-LA(Dynamic Classifier Selection - Local Accuracy) selects a classifier dynamically by comparing the local accuracy of each classifier at the test time, which inevitably requires long classification time. On the other hand, in the proposed approach, the best classifier in a local region is stored in the FSA(Feature Space Attribute) table during the training time, and the test is done by just referring to the table. Therefore, this approach enables fast classification because classification is not needed during test. Two feature space attributes are used entropy and density of k training samples around each sample. Each sample in the feature space is mapped into a point in the attribute space made by two attributes. The attribute space is divided into regular rectangular cells in which the local accuracy of each classifier is appended. The cells with associated local accuracy comprise the FSA table. During test, when a test sample is applied, the cell to which the test sample belongs is determined first by calculating the two attributes, and then, the most accurate classifier is chosen from the FSA table. To show the effectiveness of the proposed algorithm, it is compared with the conventional DCS -LA using the Elena database. The experiments show that the accuracy of the proposed algorithm is almost same as DCS-LA, but the classification time is about four times faster than that.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1438-1439
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• 2008

본 논문에서는 유방암치료에 적용되는 Microwave Hyperthermia를 이용한 국부 가열의 방법론적인 접근을 하였다. 그 결과 위상과 거리를 변수로 하여 정확성과 효율성을 2개의 높이는 알고리듬을 찾게 되었다. 그래서 실험적으로 증명하기 위하여 3개의 Waveguide antenna 및 안테나에 파워를 분배해주는 파워 디바이더를 제작하였다.

• Journal of KIISE:Software and Applications
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• v.30 no.3_4
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• pp.308-315
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• 2003

This paper proposes an approach integrating multiple segmentation methods in a systematic way, which can improve overall accuracy without deteriorating accuracy of highly confident segments of boundaries generated by constituent methods. A segmentation method produces boundary segments, which are then evaluated with an evaluation function considering pros/cons of the current and next methods to apply. Boundary segments with low confidence are replaced by a next method while the other segments are kept. These steps are repeated until all segmentation methods are applied. The proposed approach is implemented for the segmentation of muscles in the Visible Human color images. A Balloon method, a minimum cost path finding method, and a Seeded Region Growing method are integrated. The final segmentation results showed improvements in both overall evaluation and segment-based evaluation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.243-246
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• 2009

The axial local regression rate of solid fuel of hybrid rocket is one of important parameter for a design and performance. Steeping method is simple and measure a corrcet regression rate of axial direction not being relevant to a shape of fuel and physical characteristics. In this study, the problem of other measuring equipment was improved and this linear steeping method is provide higher accuracy than the other.

• Journal of KIISE:Software and Applications
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• v.29 no.3
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• pp.202-210
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• 2002

During the last few years, the extraction and reconstruction of the blood vessels in the medical image has been actively researched and the analysis for the retinal vessel structure has provided important information for diagnosis and remedy of the retinopathy patients. In this research, we propose the algorithm that tracks automatically the entire retinal vessel in retinal image acquired by the ICG(IndoCyanine Green) technology. This algorithm extracts contours and centers by estimating the local maxima and processing directions and detects bifurcations and junctions by comparing direction components of the local maxima from the gradient magnitude profile of each blood vessel. We present experimental results that the entire blood vessel is automatically reconstructed and is excellent in accuracy and connectivity after applying our algorithm to the ICG retinal images of patients.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.1
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• pp.39-58
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• 2004

It is very important that predict the inelastic seismic behavior exactly for seismic performance evaluation of a building in the performance based seismic design. Evaluation method of seismic performance based on the pushover analysis reflected in PBSE was developed by some researchers. For the evaluation of inelastic global and local seismic responses by pushover analysis exactly. lateral load distribution should be adjusted and reflected the dynamic characteristics of structural system and various seismic ground motions. And performance point should be determined based on the evaluation of reasonable deformation capacity of a building more exactly. An effective method based on the improved the adaptive lateral load distribution and the equivalent responses of a multistory building is proposed in this study to efficiently estimate the accurate inelastic seismic responses. The proposed method can be used to evaluate the seismic performance for the global inelastic behavior of a building and to accurately estimate its local inelastic seismic responses. In order to demonstrate the accuracy and validity of this method, inelastic seismic responses estimated by the proposed method are compared with those obtained from other analytical methods.

• Journal of the Korea Computer Industry Society
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• v.6 no.5
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• pp.735-740
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• 2005

Video segmentation is an essential part in region-based video coding and any other fields of the video processing. Among lots of methods proposed so far, the watershed method in which the region growing is performed for the gradient image can produce well-partitioned regions globally without any influence on local noise and extracts accurate boundaries, But, it generates a great number of small regions, which we call over segmentation problem. Therefore we proposes that adaptive trimmed mean filter for resolving the over segmentation of image.

• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.223-226
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• 2008

최근 사람의 생체정보를 이용하여 동일인 여부를 판별하는 생체인식에 대한 연구가 활발히 진행되고 있다. 지금까지 인증이나 인식에 사용된 생체 정보로는 홍채, 지문, 망막, 음성, 얼굴 등이 있으며 그 중 홍채는 신뢰성이나 정확성 면에서 우수한 성능을 가진다. 홍채 인식은 다양한 환경하에서 홍채를 취득해야 하기 때문에 주변 환경에 민감할 수 밖에 없다. 특히 홍채의 회전으로 인한 홍채 무늬 패턴의 변화에 강인한 특징을 추출하는 것은 홍채 인식에 있어 매우 중요하다. 본 논문에서는 국부적 그래디언트 방향 히스토그램을 이용한 회전된 홍채의 특징 추출 방법을 제안하였다. 제안된 방법은 성능면에서 기존의 방법들과 비교하여 대등한 성능을 보여주는 것을 실험을 통해 확인하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.33-44
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• 2006

As many scientific phenomena are now investigated using complex computer models, the effective use of Kriging on physical problems has been expanded to provide global approximations for optimization problems. This paper is focused on the two types of strategies to improve efficiency and accuracy of approximate optimization models using Kriging. These methods are performed by the stochastic process, stochastic-localization method(SLM), as the criterion to move the local domains and the design of experiments(DOE), the classical design and space-filling design. The proposed methodology is applied to the designs of 3-bar truss, Sandgren's pressure vessel, and honeycomb upper platform of a satellite structure.