• Journal of KIISE:Databases
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• v.28 no.3
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• pp.430-448
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• 2001

In navigation system, a primary task is to compute the minimum cost route from the current location to the destination. One of major problems for navigation systems is that a significant amount of computation time is required when the digital road map is large. Since navigation systems are real time systems, it is critical that the path be computed while satisfying a time constraint. In this paper, we have developed a HiTi(Hierarchical MulTi) graph model for hierarchically structuring large digital road maps to speedup the minimum cost path computation. We propose a new shortest path algorithm named SPAH, which utilizes HiTi graph model of a digital road map for its computation. We prove that the shortest path computed by SPAH is the optimal. Our performance analysis of SPAH also showed that it significantly reduces the computation time over exiting methods. We present an in-depth experimental analysis of HiTi graph method by comparing it with other similar works.

• Journal of KIISE:Software and Applications
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• v.34 no.2
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• pp.95-103
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• 2007

This paper describes an English-to-Korean automatic translation system for patent documents which is constructed by a method customizing from a general domain to a specific domain. The customizing method consists of following steps: 1) linguistically studying about characteristics of patent documents, 2) extracting unknown words from large patent documents and terminologically constructing, 3) customizing the target language words of existing terms, 4) extracting and constructing patent translation patterns peculiar to patent documents, 5) customizing existing translation engine modules according to linguistic study about characteristics of patent documents, 6) evaluation of automatic translation results. The English-to-Korean patent machine translation system implemented by these customization steps shows a translation accuracy of 81.03% and is improving.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.3
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• pp.283-292
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• 2011

This paper proposed a new multi-level inverter topology based on a H-bridge with two switches and two diodes connected to the DC-link. The output voltage of the proposed topology is quite closer to a sinusoidal waveform compared with a typical single phase inverter. The proposed multi-level inverter is applicable to a power conditioning system for renewable energy sources, and it can be also used as a building block of a cascaded multi-level inverter for a high voltage application. In case of conventional H-bridge type or NPC type multi-level inverter, 8 controllable switches are used to obtain a 5 level output voltage, but the proposed multi-level inverter requires only 6 controllable switches. Thus the circuit configuration is quite simple, reliable and cost-effective implementation is possible. The efficiency can be improved owing to the reduction of the switching loss. A new PWM method based on POD modulation is suggested which requires only one carrier signal. The switching sequence to make the capacitor voltage balanced is also considered. The feasibility is studied through simulation and experiment.

• The KIPS Transactions:PartA
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• v.13A no.2 s.99
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• pp.137-146
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• 2006

Shared Memory Multiprocessor (SMP) systems adopting Chip-level MultiThreading (CMT) technology are becoming mainstream servers in commercial applications and High Performance Computining (HPC) applications as well. OpenMP has become the standard paradigm to parallelize applications for SMP mostly because of its ease of use. As the demand for more computing power in HPC applications is growing rapidly, obtaining high performance and scalability for these applications parallelized using OpenMP API's will become more important. In this paper, we study the performance and scalability of HPC applications parallelized using OpenMP, SPEC OMPL (standard OpenMP benchmark suite), on the Sun Fire E25K server which adopts CMT technology. We also study the effect of CMT on SPEC OMPL.

• The KIPS Transactions:PartA
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• v.17A no.5
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• pp.229-236
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• 2010

With an increasing number of documents in the Internet or enterprises, it becomes crucial to efficiently support users' queries on those documents. In that situation, the full-text search technique is accepted in general, because it can answer uncontrolled ad-hoc queries by automatically indexing all the keywords found in the documents. The size of index files made for full-text searches grows with the increasing number of indexed documents, and thus the disk cost may be too large to process multi-keyword queries against those enlarged index files. To solve the problem, we propose both of the index file structure and its management scheme suitable to the processing of multi-keyword queries against a large volume of index files. For this, we adopt the structure of inverted-files, which are widely used in the multi-keyword searches, as a basic index structure and modify it to a hierarchical structure for join operations and ranking operations performed during the query processing. In order to save disk costs based on that index structure, we dynamically store in the main memory the results of join operations between two keywords, if they are highly expected to be entered in users' queries. We also do performance comparisons using a cost model of the disk to show the performance advantage of the proposed scheme.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.01a
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• pp.329-331
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• 2013

본 어플은 사회적 문제를 기술적 패러다임에 맞춰 해결하고자 기획되었다. 일반적으로 자기 자신의 문제점보다 다른 사람의 문제점이 더 쉽게 보이고 인식하게 된다. 작은 문제로 볼 수 있지만 최근 사회적 문제로 발생하고 있는 "따돌림" 문제는 인간의 존엄성마저 잃어버리게 하고 있다. 친구들의 문제뿐 아니라 부모와 자식, 형제, 자매 등 가족들과의 의사 단절 등으로 확대되고 있으며, 이런 문제를 해결하기위하여 많은 노력들을 하고 있지만, 실제 치료의 시간도 오래 걸리고 많은 금전도 필요하게 된다. 이렇기에 최근 트랜드의 축이 되고 있는 "스마트폰"을 활용하여 시간적, 공간적 제약을 최소화하고 더불어 수익성을 고려하여 "WHO"의 어플을 기획하게 되었다. 특히, 사후문제 처리가 아닌 "예방"의 목적으로 상대방의 문제점을 파악하는 것과 자신의 문제점을 인지하고 해결하는데 중점을 두었다. 내가 아닌 지인이 나에 대한 평가를 보다 객관적인 평가를 하기 위하여 대상자를 자신의 스마트폰 주소록에 한정하였으며, 악위적인 댓글 등을 최소화하기 위하여 금지어, 입력글자 개수제한 등을 추가하였다. 평점을 줄 수 있게 하여 상대적이고 객관적인 점수로 자신의 평점을 알 수 있게 하였고 보다 빠른 인지를 위하여 별모양의 그래픽을 사용하여 평가하도록 하였다. 특히, 본 어플은 설치자만이 사용할 수 있기 때문에 주소록에 있는 명단에서 "초대하기"기능으로 설치를 유도하였다. 본 어플을 개발 후 2주간의 테스트를 통하여 어플의 기대효과에 대한 가능성에 대해 확인할 수 있었으며 추가로 개발될 어플에는 분야별 항목을 추가하여 보다 섬세한 자아평가를 가능하도록 기획하고 있다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1991.04a
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• pp.127-132
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• 1991

충격에 민감한 용기나 기계들은 운반이나 보관중에 받을 수 있는 진동충격 을 완화시키기 위해 충격 마운트를 이용하게 되며, 충격마운트는 용기나 기 계들이 허용하는 최대가속도와 이들이 취급되는 환경에 의해 적절히 선정되 어야 한다. 그러므로 내충격 설계는 최대 허용 가속도나 취급환경에 대한 사 양과 이 사양에 의한 충격 마운트의 선정, 그리고 선정된 내충격 시스템의 충격시험에 의한 오일 탬퍼의 결합용이 사용되기도 하지만 구조가 복잡하고 가격이 비싸서 대용량이 경우에만 국한되어 사용되고 있으며, 가장 경제적인 것은 방진고무를 사용한 것이다. 내충격 시스템은 일반적으로 큰 변형량을 요구하고 있으며, 방진고무의 경우 큰 변형에서는 hardening 스프링의 비선 형성을 가지고, 형상계수와 고무배합율에 따라 정적 스프링상수와 동적 스프 링상수가 큰 차이를 보이는 등, 설계상의 여러 제한이 있다. 그러나 방진고 무는 형상변화가 자유로우며 제작이 용이하기 때문에 이러한 장점을 이용하 면 저렴하고 다양한 용도의 충격마운트 제작에 효과적으로 사용될 수 있다. 본 논문에서는 원통형 콘테이너의 내충격 설계를 위해 충격사양에 의한 충 격마운트의 설계, 설계된 내충격 시스템의 충격시험에 의한 검증을 순차적으 로 실시하여, 방진고무를 이용한 충격마운트 설계기술을 제시함으로써, 이후 방진고무제품의 설계를 위한 자료 및 과정의 제정에 도움을 주고자 한다.

• Journal of the Korean Society for information Management
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• v.21 no.4 s.54
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• pp.251-263
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• 2004

For question-answering system, question analysis module finds the question points from user's natural language questions, classifies the question types, and extracts some useful information for answer. This paper proposes a question type classifying technique based on focus words extracted from questions and word semantic information, instead of complicated rules or huge knowledge resources. It also shows how to find the question type without focus words, and how useful the synonym or postfix information to enhance the performance of classifying module.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.6
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• pp.1403-1408
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• 2010

Korean information retrieval uses noun as index terms or keywords of representing the document. and noun and keyword extraction is to find all nouns presented in the document, In this paper, we proposes the method of keyword extraction using pre-built dictionary. This method reduces the execution time by reducing unnecessary operations. And noun, even large documents without affecting significantly the accuracy, can be extracted. This paper proposed noun extraction method using the appearance characteristics of the noun and keyword extraction method using unsupervised learning techniques.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9C
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• pp.884-890
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• 2003

In this paper, we studied the speaker adaptation methods that improve the speaker independent recognition system. For the independent speakers, we compared the results between bigram and back-off bigram, MAP and MLLR. Cause back-off bigram applys unigram and back-off weighted value as bigram probability value, it has the effect adding little weighted value to bigram probability value. We did an experiment using total 39-feature vectors as featuring voice parameter with 12-MFCC, log energy and their delta and delta-delta parameter. For this recognition experiment, We constructed a system made by CHMM and tri-phones recognition unit and bigram and back-off bigrams language model.