• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.235-239
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• 1996

분류가 모서리에 충돌할 때 발생하는 순음성 소리인 쐐기소리(edgetone)는 공력음향의 대표적인 현상으로서 지금까지 수많은 연구가 있어 왔으며 그 대부분의 특성이 규명되었다고 할 수 있다. 쐐기소리의 발생기구인 되먹임(feedback) 이론을 처음으로 제안한 이는 Powell로서 그는 되먹임사이클의 위상조건에 의하여 주파수특성에 관한 모델을 제안하였으며, 최근 그 모델의 위상인자에 관하여 Kwon은 새로운 값을 제안한 바 있다. 그런데, 쐐기소리의 이론은 주로 분류가 쐐기나 벽에 충돌할 경우에 집중되어 왔으며 분류가 원통에 충돌하여 발생하는 경우에 관한 연구는 Krothapalli의 초음속분류에 관한 연구와 Mochizuki등의 아음속분류에서 원통지름의 영향에 관한 연구를 들 수 있을 뿐이다. Mochizuki등은 원통의 지름이 노즐의 높이보다 작은 경우에 쐐기 소리의 주파수가 원통의 와류이탈(vortex shedding) 주파수와 같은 것을 관찰하였다. 그러나 분류와 원통이 작용하여 발생하는 쐐기소리의 주파수 특성에 관한 이론적 해석을 시도한 연구는 없으며 또한 방사음장의 특성에 관하여도 Han과 Kwon에 의한 모델이 발표된 바 있으나 실험적으로 입증되지 못하였다. 따라서, 본 연구의 목적은 2 fig.1과 같이 2차원 분류가 원통에 충돌할 때 발생하는 쐐기소리의 주파수특성의 정량적인 모델을 세우고 방사음장의 지향특성의 이론 모델을 확립하는 것이다. 먼저 주파수특성을 실험하고 되먹임이론을 적용하여 분석하므로써 유효음원의 위치를 구하고 또한, 수직벽에 작용하여 발생하는 충돌음(impinging tone)의 경우를 실험하여 주파수특성을 비교 고찰하므로써 유효음원의 위치에 관한 이론을 입증한다. 아울러 원통과 평면벽의 각 경우에 방사음장의 지향특성을 측정하고 고찰한다.2,5,6]을 단계별로 고찰하여, 점점 까다로워져 가는 선박 진동규제[3,4]에 대처하고 승무원의 안락성에 대한 욕구, 구조물의 안전성, 장비의 성능보존이 만족되는 저진동 선박의 건조를 위해 향후 해결해야할 과제들을 도출하여 선박진동분야이 연구개발 방향을 제시하고자 한다. 하는 것은 진단의 정밀도에 문제가 있을 것으로 생각된다. 따라서 언어적진리치가 도입되어 [상당히 확실], [확실], [약간 확실] 등의 언어적인 표현을 이용하여 애매성을 표현하게 되었다. 본 논문에서는 간이진단 결과로부터 추출된 애매한 진단결과중에서 가장 가능성이 높은 이상원인을 복수로 선정하고, 여러 종류의 수치화할 수 없는 언어적(linguistic)인 정보ㄷㄹ을 if-then 형식의 퍼지추론으로 종합하는 회전기계의 이상진단을 위한 정밀진단 알고리즘을 제안하고 그 유용성을 검토한다. 존재하여도 모우드 변수들을 항상 정확하게 구할 수 있으며, 또한 알고리즘의 안정성이 보장된 것이다.. 여기서는 실험실 수준의 평 판모델을 제작하고 실제 현장에서 이루어질 수 있는 진동제어 구조물에 대 한 동적실험 및 FRS를 수행하는 과정과 동일하게 따름으로써 실제 발생할 수 있는 오차나 error를 실험실내의 차원에서 파악하여 진동원을 있는 구조 물에 대한 진동제어기술을 보유하고자 한다. 이용한 해마의 부피측정은 해마경화증 환자의 진단에 있어 육안적인 MR 진단이 어려운 제한된 경우에만 실제적 도움을 줄 수 있는 보조적인 방법으로 생각된다.ofile whereas relaxivity at high field is not affected by τS. On the other hand, the change in τV does not affect low field profile but strongly in fluences on both

• Journal of Environmental Impact Assessment
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• v.4 no.2
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• pp.105-121
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• 1995

Nitrate contamination problems from groundwater supplies have been documented throughout many countries in the world, including Korea. Nitrate salts can induce methemoglobinemia and possibly human gastric cancer. In farmed areas. intensive agricultural activities have caused a major increase in nitrate loading to groundwater. To determine whether decision makers must take farm-management actions to control the increase of groundwater nitrate concentration and to decide the timing of such actions, it is important to predict groundwater Nitrate levels that would result over time from various farm-management practices. However, the input values such as soil, fertilizer and crop data) used to examine the effects of various farm-management practices on groundwater nitrate level are usually uncertain due to a lack of available information. In this paper. the ease of a community with a nitrate water quality problem is illustrated to examine the effects of various farm-management practices and to show bow to perform, with uncertain information. a time-series analysis on groundwater nitrate levels that would result. from each farm-management practice.

• The Journal of the Korea Contents Association
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• v.14 no.2
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• pp.192-204
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• 2014

Gist-based message design is essential in the Internet in which a lot of health messages are created and shared constantly. This study intended to identify the characteristics of health messages in a webzine and explore a way to design gist-based health messages. A total of 72 webzine articles published in Korean Ministry of Food and Drug Safety were selected, and text and visual messages of the articles were analyzed in terms of content types, the frequency and position of gists, and intuitive expression. The articles were also categorized regarding the characteristics of health messages through cluster analyses. This study found that most texts of the health articles consisted of facts and methods, while most visual messages represented concepts. In addition, both text and visual messages had limitations in presenting a gist effectively. It was also necessary to explore an effective way to improve an intuitive understanding of jargon and quantitative information in health messages. Based on these findings, this study provided suggestions for the design of gist-based health messages in the Internet.

• The Journal of the Korea Contents Association
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• v.18 no.5
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• pp.280-291
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• 2018

Recently, various interactions have been actively conducted through sharing and expressing opinions among users in social networks. In this process, since malicious users and fault information spread misinformation, trust is reduced irrespective of their will. To solve this problem, studies have been conducted to determine the trust of a user through direct-connected users. In this paper, we propose a enhanced user indirect trust discrimination scheme considering the connection relation and influence of users. The proposed indirect trust computation scheme derives the user's area of interest through user interaction and reconstructs the existing network considering the user connection relationship. The final indirect trust is also detected by determining whether the user is a malicious user through the influence of the user. Through various performance evaluations, we show that the proposed scheme achieves better performance than the existing method.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.6
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• pp.52-62
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• 1999

This paper presents a system which recognizes dynamic hand gestures on-line for controlling motion of numan avatar in virtual environment(VF). A dynamic hand gesture is a method of communication between a computer and a human being who uses gestures, especially both hands and fingers. A human avatar consists of 32 degree of freedom(DOF) for natural motion in VE and navigates by 8 pre-defined dynamic hand gestures. Inverse kinematics and dynamic kinematics are applied for real-time motion control of human avatar. In this paper, we apply a fuzzy min-max neural network and feature analysis method using fuzzy logic for on-line dynamic hand gesture recognition.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.6
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• pp.759-764
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• 2005

In this paper we describe a face recognition using EBGM(Elastic Bunch Graph Matching) method. Usally, the PCA and LDA based face recognition method with the low-dimensional subspace representation use holistic image of faces, but this study uses local features such as a set of convolution coefficients for Gabor kernels of different orientations and frequencies at fiducial points including the eyes, nose and mouth. At pre-recognition step, all images are represented with same size face graphs and they are used to recognize a face comparing with each similarity for all images. The proposed algorithm has less computation time due to simplified face graph than conventional EBGM method and the fuzzy matching method for calculating the similarity of face graphs renders more face recognition results.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.7 no.3
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• pp.133-141
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• 2012

Service and manufacturing companies' efforts are increasingly focused on utilizing services to satisfy customers' needs and survive in today's competitive market environment. The value of services depends mainly on service reliability that is identified by satisfaction derived from the relationship between customer and service provider. In this paper, we extend concepts from the failure modes and effects analysis of tangible systems to services. We use an event-based process model to facilitate service design and represent the relationships between functions and failures in a service. The objective of this research is to propose a method for evaluating service reliability based on service processes using fuzzy failure mode effects analysis (FMEA) and grey theory. We define the failure mode of service as interaction ways that can be failed in a service delivery process. The fuzzy set theory is used to characterize service reliability based on linguistic terms during FMEA. Grey theory is employed to determine the degree of relation and ranking among risk factors that are represented as potential failure causes. To demonstrate implementation of the proposed method, we use a case study involving a typical automotive service operation.

• Journal of the Korean Institute of Navigation
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• v.18 no.3
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• pp.1-9
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• 1994

종래(從來)의 내비게이션시스템은 주로 선박(船舶)을 대상(對象)으로 이용되어왔으나, 최근(最近)에는 각종(各種) 이동(移動)로보트 및 자동차(自動車)에 대한 적용사례(適用事例)가 증가(增加)하고 있다. 내비게이션시스템은 기계적(機械的)인 이동(移動)시스템뿐만 아니라, 이동(移動)이라는 행동(行動)을 취하는 인간(人間)시스템 즉, 시각(視覺) 부자유자(不自由者를) 대상(對象)으로 적용(適用)될 수 있다. 종래(從來)의 기계적(機械的)인 맹인용(盲人用) 가이딩시스템으로서 맹도견(盲導犬)로보트가 있으나 계단(階段)등의 복잡(複雜)한 환경하(環境下에)서는 안내(案內)가 불가능(不可能)한 점과 맹인(盲人)의 의사(意思)가 반영(反映)되기 어렵다는 점 등의 많은 문제점(問題點)을 안고 있다. 현실적(現實的)으로 요구(要求)되는 안내(案內)시스템은, 단지 환경(環境)에 관한 각종정보(各種情報)를 제공(提供)하고 의사결정(意思決定)과 행동(行動)은 맹인(盲人)이 실시(實施)하는 시스템의 형태(形態)이다. 본논문(本論文)에서는, 맹인용(盲人用) 내비게이션시스템의 구축(構築)을 목표(目標)로 하는 중간과제(中間課題)로서, 화상(畵像)을 이용(利用)한 언어적(言語的) 가이드시스템을 제안(提案)한다. 당해(當該)시스템 구축(構築)에 있어서 중요(重要)한 과제(課題)는, 주어진 환경(環境)에 관한 화상정보(畵像情報)를 언어(言語)로 변환(變換)시키는 일이다 본연구(本硏究)에서는, 가이드를 위한 언어지원(言語指元) 생성(生成)에, 정성적(定性的), 정량적(定量的)인 속성(屬性)을 가지고 언어적(言語的) 표현(表現)에 유효(有效)한 퍼지이론(理論)을 이용(利用)한다. 구체적(具體的)인 일례(一例)로서, 공원(公園)에서 벤치까지 맹인(盲人)을 가이드하는 상황(狀況)을 설정하고 언어지원(言語指元)을 생성(生成)하는 알고리즘을 제안(提案)한다.

• Nuclear Engineering and Technology
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• v.28 no.1
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• pp.36-43
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• 1996

In this work, a PC-based thermal performance monitoring system is developed for the nuclear power plants. The system performs real-time thermal performance monitoring and diagnosis during plant operation. Specifically, a prototype for the KORI-2 nuclear power unit is developed and examined in this work. The analysis and the fault identification of the thermal cycle of a nuclear power plant is very difficult because the system structure is highly complex and the components are very much inter-related. In this study, some major diagnostic performance parameters are selected in order to represent the thermal cycle effectively and to reduce the computing time. The Fuzzy ARTMAP, a self-organizing neural network, is used to recognize the characteristic pattern change of the performance parameters in abnormal situation. By examination, this algorithm is shown to be able to detect abnormality and to identify the fault component or the change of system operation condition successfully. For the convenience of operators, a graphical user interface is also constructed in this work.

• Archives of design research
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• v.19 no.2 s.64
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• pp.81-90
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• 2006

Pedestrians perceive differently from the sideway views or the exteriors of the buildings on the way to their destinations. Therefore, the navigation experience can become much different when the path was chosen based on the individual's preference from it is not. By focusing on the effects of the individual pedestrian' path choice on their navigation, this paper presents an algorithm designed for pedestrians to be able to explore their preferred path and proposes a prototype of navigation system based on the algorithm. The navigation support system searches for the best path upon their individual preferences and information of the destination. The system provides the process of retrieving the final path via the pedestrian-support system interaction. The path retrieval is peformed with the combinational matrix of keywords that are formulates Fuzzy theory from the correlations between the terms describing preferences used in the path preference survey. This paper presents the potentials of the path finding method tailored to pedestrians' preferences by a simulation of the proposed path retrieval algorithm.