• Journal of Korean Institute of Industrial Engineers
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• v.29 no.1
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• pp.90-99
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• 2003

Object clustering, which makes classification for a set of objects into a number of groups such that objects included in a group have similar characteristic and objects in different groups have dissimilar characteristic each other, has been exploited in diverse area such as information retrieval, data mining, group technology, etc. In this study, an object-clustering problem with similarity coefficients between objects is considered. At first, an evaluation function for the optimization problem is defined. Then, a genetic algorithm and local optimization technique based on heuristic method are proposed and used in order to obtain near optimal solutions. Solutions from the genetic algorithm are improved by local optimization techniques based on object relocation and cluster merging. Throughout extensive experiments, the validity and effectiveness of the proposed algorithms are tested.

• IE interfaces
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• v.12 no.2
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• pp.237-246
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• 1999

The Automated Storage/Retrieval System(AS/RS) is very expensive to be built. But there are few tools available which can be used to design the storage systems optimally considering overall system building costs and constraints. In this paper, we propose a design support system for optimal design of AS/RS which includes different sized cells using expert systems and mathematical models considering customer's demands. The optimization models are to be used to minimize the total cost including building, equipment and operation costs. Expert system technique is utilized for using the experiences of skilled designers. By using the proposed system, AS/RS can be designed accurately, economically and efficiently.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07b
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• pp.7-9
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• 2005

온톨로지 언어를 기반으로 하는 시맨틱 웹 상에서 온톨로지 데이터에 대한 질의를 효율적으로 처리하기 위해서는 질의 처리에 효과적인 저장 스키마의 구축이 필요하다. 본 논문에서는 온톨로지 데이터의 검색을 위한 효과적인 저장 스키마 구축 기법을 제안하고자 한다. 아울러 본 논문에서 제안하는 저장 스키마를 위한 질의 기법을 제안하고자 한다. 온톨로지 데이터를 추출할 때에는 계층 구조를 기반으로 질의 수행을 해야 한다. 따라서 본 논문에서는 계층 정보를 유지하기 위해 별도의 XML 문서를 기존의 넘버링 기법을 기반으로 생성하여 하위 정보의 추출을 효과적으로 지원하고자 한다. 실험을 통한 질의 처리 성능을 통해서 본 논문에서 제안하는 저장 스키마 기법과 질의 처리 기법이 효과적임을 보인다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07b
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• pp.844-846
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• 2005

본 논문에서는 3차원 모델을 검색하기 위한 형태 기반 기술자를 추출하는 알고리즘을 제안한다. 제안하는 알고리즘은 모델의 기하학적인 특성을 고려하여 레이 캐스팅 샘플링과 구면조화함수를 이용하는 방법이다. 레이 캐스팅 기법은 모델의 외형을 고려한 적응적인 방법으로 샘플링 하여 기술자에 포함되는 형태 정보를 증가시켜 기술자의 식별성을 높인다. 또한 구면조화함수 계수 추출에서는 기하학적인 주파수 특성을 고려하여 적응적인 계수를 추출한다. 이 방법은 검색 성능에 영향을 미치지 않고 기술자를 조밀하고 간결하게 만든다. 최종적으로 두 방법을 결합함으로써 검색 엔진에서 이용 가능한 기술자를 생성한다. 실험 결과에서는 제안된 알고리즘의 성능이 기존 방법에 비해 약 $12.5\%$ 향상 된 것을 확인 할 수 있다.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.491-492
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• 2003

The large amount of smoke produced near Lake Baikal was transported to Northeast Asia with high AOT (Aerosol Optical Thickness) as seen in satellite images. Aerosol retrieval using a separation technique was applied to MODIS (Moderate Imaging Spectroradiometer) and SeaWiFS (Sea-viewing Wide Field-of-view Sensor) data observed during 14-22 May 2003. Large AOT, 2.0~5.0 was observed on 20 May 2003 over Korea due to the influence of the long range transport of smoke aerosol plume from the Russian fires, resulting in high PM10 concentration was observed at the surface.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10a
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• pp.57-59
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• 1999

현재 WWW(World Wide Web), 사무 자동화 시스템(Office Information System), 전자 도서관(Digital Library) 등의 빠른 발전으로 인하여 정보가 기하급수적으로 증가하였다. 이러한 방대한 양의 정보를 처리하기 위하여 많은 인터넷 기반의 문서 표준들이 출현하였고, 대표적으로 XML(eXtensible Markup Language)이 차세대 인터넷 전자 문서의 표준으로 많은 곳에 응용되고 있다. 이에 따라 XML 문서의 정보들을 효율적이고 정확하게 저장하고 이용, 검색 할 수 있는 기능을 요구되어졌다. 현재 대부분의 연구들은 XML 문서에 대한 구조적인 정보만을 저장하고 검색하는 기능만을 지원 할 뿐 검색된 결과에 대한 재사용이나 재구성에 대한 기능의 제공은 미흡한 실정이다. 본 논문에서는 현재 검색기들이 제공하는 XML 문서에 대한 구조적인 검색 기능을 확장하여 XML 문서를 보다 효율적으로 검색하기 위하여 새로운 색인 기법을 제안하고, 데이터베이스 내에 저장된 XML문서에 대해 구조적인 검색과 이것을 바탕으로 문서를 재구성하고 재사용하는 기능을 수행할 수 있도록 새로운 질의어(TQL)을 설계하였다.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.27 no.4
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• pp.69-76
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• 2004

A framework for knowledge management system has been explored which enables the semantic search of knowledge on the web. Knowledge representation by RDF and RDF schema enables machine cognition of knowledge documents. Dublin core was adopted for structured metadata representation. Thereby, it enables the CBR and rule based reasoning for intelligent knowledge retrieval. Grafting of the WFMS technique unto the KMS facilitates the effective utilization of process knowledge and creation of new knowledge.

• Journal of Chest Surgery
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• v.54 no.4
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• pp.314-318
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• 2021

In this paper, I present the technique of subxiphoid single-port video-assisted thoracic surgery (VATS) thymectomy for thoracic surgeons to perform this procedure safely. This procedure is indicated for all anterior mediastinal masses and may be extended to lung cancer. The patient is placed in the lithotomy position, and the operator should be on the midline. Below the xiphoid process, a skin incision is made 4-5 cm horizontally at a single thumb's width down. Under two-lung ventilation, CO₂ is insufflated, maintaining 10 mm Hg. The fat tissue and thymic tissue are all resected from the sternum and pericardium between both phrenic nerves using an articulated grasper and an energy device. After retrieval of the mass with a wrap bag, a Jackson-Pratt drain is inserted instead of a chest tube. One of the advantages of this procedure is less postoperative pain than intercostal VATS. The subxiphoid approach can be used for bilateral pneumothorax, bilateral pulmonary metastasectomy, and simple lobectomy for both upper lobes and the right middle lobe.

• Journal of Korea Multimedia Society
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• v.7 no.12
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• pp.1671-1679
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• 2004

This study has proposed visual-feature extraction methods for each band in wavelet domain with both spatial frequency features and multi resolution features. In addition, it has brought forward similarity measurement method using fuzzy theory and new color feature expression method taking advantage of the frequency of the same color after color quantization for reducing quantization error, a disadvantage of the existing color histogram intersection method. Experiments are performed on a database containing 1,000 color images. The proposed method gives better performance than the conventional method in both objective and subjective performance evaluation.

• Current Optics and Photonics
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• v.7 no.5
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• pp.537-544
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• 2023

Differential phase contrast (DPC) microscopy, a central quantitative phase imaging (QPI) technique in cell biology, facilitates label-free, real-time monitoring of intrinsic optical phase variations in biological samples. The existing DPC imaging theory, while important for QPI, is grounded in paraxial diffraction theory. However, this theory lacks accuracy when applied to high numerical aperture (NA) systems that are vital for high-resolution cellular studies. To tackle this limitation, we have, for the first time, formulated a nonparaxial DPC imaging equation with a transmission cross-coefficient (TCC) for high NA DPC microscopy. Our theoretical framework incorporates the apodization of the high NA objective lens, nonparaxial light propagation, and the angular distribution of source intensity or detector sensitivity. Thus, our TCC model deviates significantly from traditional paraxial TCCs, influenced by both NA and the angular variation of illumination or detection. Our nonparaxial imaging theory could enhance phase retrieval accuracy in QPI based on high NA DPC imaging.