• 한국안전학회지
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• 제36권2호
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• pp.49-57
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• 2021

In the case of military supplies, any potential failure and causes of failures must be considered. This study is aimed at examining the failure modes of a rotorcraft landing system to identify the priority items. Failure mode and effects analysis (FMEA) is applied to the rotorcraft landing system. In general, the FMEA is used to evaluate the reliability in engineering fields. Three elements, specifically, the severity, occurrence, and detectability are used to evaluate the failure modes. The risk priority number (RPN) can be obtained by multiplying the scores or the risk levels pertaining to severity, occurrence, and detectability. In this study, different weights of the three elements are considered for the RPN assessment to implement the FMEA. Furthermore, the FMEA is implemented using a fuzzy rule base, similarity aggregation model (SAM), and grey theory model (GTM) to perform a comparative analysis. The same input data are used for all models to enable a fair comparison. The FMEA is applied to military supplies by considering methodological issues. In general, the fuzzy theory is based on a hypothesis regarding the likelihood of the conversion of the crisp value to the fuzzy input. Fuzzy FMEA is the basic method to obtain the fuzzy RPN. The three elements of the FMEA are used as five linguistic terms. The membership functions as triangular fuzzy sets are the simplest models defined by the three elements. In addition, a fuzzy set is described using a membership function mapping the elements to the intervals 0 and 1. The fuzzy rule base is designed to identify the failure modes according to the expert knowledge. The IF-THEN criterion of the fuzzy rule base is formulated to convert a fuzzy input into a fuzzy output. The total number of rules is 125 in the fuzzy rule base. The SAM expresses the judgment corresponding to the individual experiences of the experts performing FMEA as weights. Implementing the SAM is of significance when operating fuzzy sets regarding the expert opinion and can confirm the concurrence of expert opinion. The GTM can perform defuzzification to obtain a crisp value from a fuzzy membership function and determine the priorities by considering the degree of relation and the form of a matrix and weights for the severity, occurrence, and detectability. The proposed models prioritize the failure modes of the rotorcraft landing system. The conventional FMEA and fuzzy rule base can set the same priorities. SAM and GTM can set different priorities with objectivity through weight setting.

• 한국정보처리학회논문지
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• 제6권9호
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• pp.2350-2364
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• 1999

본 논문은 객체지향 C++ 클래스 컴포넌트를 분류하여 재사용자에게 필요한 컴포넌트를 제공하기 위한 저장소의 클래스 라이브러리 설계방법을 제안한 것이다. 클래스 라이브러리를 설계하기 위해서 컴포넌트 구성 모델을 정의하였고, Enumerative 분류 방법을 이용한 멀티미디어 영역을 분류하였으며, 문서 클러스터링 방법을 확장하여 유사도에 의한 C++ 클래스를 유사한 그룹으로 분류하는 클러스터 생성 기준을 제안하고 있다. 이 유사 그룹인 클러스터는 클래스 멤버 데이터와 멤버함수 그리고 클래스 유사도를 기반으로 분류되며, 분류된 컴포넌트들은 유사도 관계의 계층구조로 구성된다. 마지막으로 객체지향 개념인 Generalization/Specialization의 C++ 상속관계를 계층구조로 표현할 수 있는 클래스 라이브러리를 설계하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.849-851
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• 2003

A location-based service or LBS in a cellular telephone network is a service provided to the subscriber based on his current geographic location. This position can be known by user entry or a GPS receiver that he carries with him, but most often the term implies the use of a function built into the cell network that uses the known geographic coordinates of the base stations through which the communication takes place. One implication is that knowledge of the coordinates is owned and controlled by the network operator, and not by the end user. Location utility service provides two kinds of functions, geocoder and reverse geocoder. Geocoder converts an address into a coordinate and reverse geocoder changes a coordinate into an address. Because location utility service is the first step to progress LBS, various servises such as directory, routing, presentation, and etc require to access that. In this paper, we will describe the architecture of LBS platform and the concept and the role of location utility service.

• 한국디지털정책학회:학술대회논문집
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• 한국디지털정책학회 2007년도 춘계학술대회
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• pp.79-87
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• 2007

This paper aims to offer a solution based on semantic document classification to improve e-Government utilization and efficiency for people using their own information retrieval system and linguistic expression Generally, semantic document classification method is an approach that classifies documents based on the diverse relationships between keywords in a document without fully describing hierarchial concepts between keywords. Our approach considers the deep meanings within the context of the document and radically enhances the information retrieval performance. Concept Weight Document Classification(CoWDC) method, which goes beyond using exist ing keyword and simple thesaurus/ontology methods by fully considering the concept hierarchy of various concepts is proposed, experimented, and evaluated. With the recognition that in order to verify the superiority of the semantic retrieval technology through test results of the CoWDC and efficiently integrate it into the e-Government, creation of a thesaurus, management of the operating system, expansion of the knowledge base and improvements in search service and accuracy at the national level were needed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2040-2042
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• 2003

In this paper, we propose a new method about wavelet-based fuzzy modeling using a DNA coding method. DNA coding techniques is known that expression of knowledge is various than Genetic Algorithm(GA) usually by made optimization technique because done base in structure of biologic DNA and optimization performance is superior. The reposed method make fuzzy system model in wavelet transform and equivalence relation after identification with coefficient of wavelet transform using a DNA coding techniques. Also, can get fuzzy model effectively of nonlinear system using advantage of strong wavelet transform about function that have sudden change. In this paper, in order to demonstrate the superiority of the proposed method compared with GA.

• 한국항해학회지
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• 제9권1호
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• pp.41-81
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• 1985

Tidal phenomenon can be utilized by the wise and cautious mariner to safely perform his duties as pilot and navigator. It can be either a help or hindrance to the mariner. The principle of MULDAE which expresses the determination of the state of the tide based upon knowledge of the lunar date and it has been used in Korea since ancient times. The folk method of calculation was essentially based on an unsystematic division of the lunar month, traditionally using the numbers 7 or 8. As the lunar cycle is complete in 15 days the tidal cycle should also correspondence closely to the lunar date. This paper represents the first scientific attempt to systematically investigate this unique traditional method of tidal calculation and contains a comparison of the MULDAE and ordinary (solar based) tide calculation methods. MULDAE was compared with the standard tide table for standard and island ports in Korea from 1982 to 1985. This study concluded that MULDAE was indeed an accurate adn reliable predictor of tidal activity. Furthermore, the number 6 was found to be the correct divisor upon which to base MULDAE calculations Also a formula expressing MULDAE as a function was discovered. This research show that MULDAE can be applied nationwide and is a reliable and easy way to predict tides based upon mean figures for certain ports and island A calender showing MULDAE is presented here for the first time. A clear relationship between the MULDAE method of calculating tides and the use of ordinary tide tables is proven.

• 정보처리학회논문지D
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• 제15D권1호
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• pp.47-60
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• 2008

시맨틱 웹 응용의 성공은 현재 웹 기술을 바탕으로 하여, 지식에 대한 규칙과 추론 기능이 제공되는 웹 온톨로지 구축에 달려있다. 이를 위해 본 연구는 기존에 제안된 온톨로지 구축기법들을 비교 분석하고, 시맨틱웹과 웹 온톨로지의 특징을 조사하여 시맨틱 웹 응용의 기반기술이 되기 위한 웹 온톨로지의 기술적 특징과 지식표현 단계를 정의하고, 현재 웹 기술과 관련되는 웹 온톨로지의 기술적 요소를 연구하였다. 이를 바탕으로 시맨틱 웹 응용을 위한 웹 온톨로지 구축기법을 제안하고, 제안한 구축기법을 적용하여 다양한 지식분야의 웹 온톨로지들을 구축하였으며, 구축된 웹 온톨로지들의 추론 검증 결과를 통해 제안된 구축방법이 기존 온톨로지 구축기법들에 비해 시맨틱 웹 응용의 요구 조건을 충족하는 결과가 획득됨을 확인하였으며, 따라서 제안한 웹 온톨로지 구축기법이 시맨틱 웹 응용에 적합한 구축기법임을 증명하였다.

• Structural Engineering and Mechanics
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• 제17권2호
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• pp.215-244
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• 2004

There is an ever-increasing demand for assessment of earthquake effects on transportation structures, emphasised by the crippling consequences of recent earthquakes hitting developed countries reliant on road transportation. In this work, vulnerability functions for RC bridges are derived analytically using advanced material characterisation, high quality earthquake records and adaptive inelastic dynamic analysis techniques. Four limit states are employed, all based on deformational quantities, in line with recent development of deformation-based seismic assessment. The analytically-derived vulnerability functions are then compared to a data set comprising observational damage data from the Northridge (California 1994) and Hyogo-ken Nanbu (Kobe 1995) earthquakes. The good agreement gives some confidence in the derived formulation that is recommended for use in seismic risk assessment. Furthermore, by varying the dimensions of the prototype bridge used in the study, and the span lengths supported by piers, three more bridges are obtained with different overstrength ratios (ratio of design-to-available base shear). The process of derivation of vulnerability functions is repeated and the ensuing relationships compared. The results point towards the feasibility of deriving scaling factors that may be used to obtain the set of vulnerability functions for a bridge with the knowledge of a 'generic' function and the overstrength ratio. It is demonstrated that this simple procedure gives satisfactory results for the case considered and may be used in the future to facilitate the process of deriving analytical vulnerability functions for classes of bridges once a generic relationship is established.

• 전자공학회논문지CI
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• 제41권1호
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• pp.1-8
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• 2004

인터넷의 발달과 데이터베이스의 구축이 보편화됨에 따라 막대한 양의 데이터 속에서 의사 결정에 필요한 지식을 찾아내는 작업은 결코 쉬운 일이 아니다 본 논문에서는 대규모 데이터의 효율적인 분석을 위하여 지식의 탐사 이전에 데이터에 대한 축소 작업을 수행하기 위한 효과적인 차원 축소 전략에 의한 패턴분류 기법을 제안한다. 이를 위해 본 논문에서는 통계적학습 모형인 Support Vector Machine의 VC-dimension에 기반한 RBF 신경망 모형을 제안한다. 기존의 RBF 신경망 모형은 주로 퍼셉트론 모형의 전처리 작업만을 수행하지만 제안하는 신경망 모형은 VD-dimension과 연계한 독자적으로 데이터를 분석할 수 있는 능력을 갖춘 모형을 구축하고 이를 바탕으로 개체들을 정확한 레이블로 분류한다. 기계 학습 데이터를 이용하여 본 논문에서 제안하는 모형의 성능을 비교 평가한 결과 기존의 여러 분류 알고리즘에 비해 우수한 성능을 보임이 실험을 통해 확인되었다.

• 정보관리연구
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• 제37권3호
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• pp.61-84
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• 2006

본 논문은 시소러스 구축 시 직면하는 문제점과 구축방법을 비판적으로 검토하고, 여러 가지 구축 방법 중 직접구축 방법을 제안하였다. 또한, 확장검색의 효율성을 보장할 수 있는 시소러스 구축을 위해 의미적 준거인 개념패싯, 관계패싯 등의 도입과 활용을 도입하였으며, 이를 이용하여 구축한 과학기술분야 시소러스의 구축사례를 제시하였다. 특별히, 패싯이 반영된 시소러스에는 다양한 관점이 반영될 수 있으므로 검색의 효율성이 보장된다는 장점이 있고, 인접 과학기술분야에 응용될 수 있다. 일례로 본 시소러스는 과학기술 연구자들의 협업을 지원하기 위한 정보유통 서비스에 응용될 수 있으며, 향후 고도화된 지식 서비스에도 확장 응용될 수 있다.