• 대한전기학회논문지:시스템및제어부문D
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• 제54권9호
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• pp.539-546
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• 2005

This paper describes a method of building the probability grid map for an autonomous mobile robot using the ultrasonic DAF(data association filter). The DAF, which evaluates the association of each data with the rest and removes the data affected by the specular reflection effect, can improve the reliability of the data for the Probability grid map. This method is based on the evaluation of possibility that the acquired data are all from the same object. Namely, the data from specular reflection have very few possibilities of detecting the same object, so that they are excluded from the data cluster during the process of the DAF. Therefore, the uncertain data corrupted by the specular reflection and/or multi-path effect, are not used to update the probability map, and hence building a good quality of a grid map is possible even in a specular environment. In order to verify the effectiveness of the DAF, it was applied to the Bayesian model and the orientation probability model which are the typical ones of a grid map. We demonstrate the experimental results using a real mobile robot in the real world.

• 대한기계학회논문집
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• 제16권4호
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• pp.675-683
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• 1992

본 연구에서는 저자에 의해 유도된 바 있는 베이지안 업데이트 모델을 초음파 센서를 갖는 실제 로봇에 주입하여 실험하였다. 초음파센서는 비교적 큰 빔(beam)구 경 때문에 단독의 측정치로도 넓은 영역을 감지하는데는 효율적이다. 그러나 실제상 황에서는 거울효과(specular reflection effect)라는 매우 심각한 문제점을 갖고 있으 며, 이는 지도의 질을 매우 저하시킨다. 이 효과를 상당히 줄일 수 있는, 단순하면 서도 실질적인 방법이 제안된다. 또한 본 논문에서는 이동로봇의 실시간 장애물 회 피를 위한 새로운 방법이 소개된다. 이 방법은 로봇의 현재 위치와, 점령영역과 비 점령 여역 사이의 경계선과 목표지점의 교차점까지의 거리를 이용하며, 점들이 실제 상황에서의 실험을 통해 입증된다.

• Journal of Communications and Networks
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• 제17권1호
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• pp.75-83
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• 2015

In mobile ad-hoc networks (MANETs), nodes are mobile in nature. Collaboration between mobile nodes is more significant in MANETs, which have as their greatest challenges vulnerabilities to various security attacks and an inability to operate securely while preserving its resources and performing secure routing among nodes. Therefore, it is essential to develop an effective secure routing protocol to protect the nodes from anonymous behaviors. Currently, game theory is a tool that analyzes, formulates and solves selfishness issues. It is seldom applied to detect malicious behavior in networks. It deals, instead, with the strategic and rational behavior of each node. In our study,we used the dynamic Bayesian signaling game to analyze the strategy profile for regular and malicious nodes. This game also revealed the best actions of individual strategies for each node. Perfect Bayesian equilibrium (PBE) provides a prominent solution for signaling games to solve incomplete information by combining strategies and payoff of players that constitute equilibrium. Using PBE strategies of nodes are private information of regular and malicious nodes. Regular nodes should be cooperative during routing and update their payoff, while malicious nodes take sophisticated risks by evaluating their risk of being identified to decide when to decline. This approach minimizes the utility of malicious nodes and it motivates better cooperation between nodes by using the reputation system. Regular nodes monitor continuously to evaluate their neighbors using belief updating systems of the Bayes rule.

• Journal of the Korean Data and Information Science Society
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• 제24권6호
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• pp.1531-1541
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• 2013

This paper proposes a new method of VaR forecasting using the conditional autoregressive VaR (CAViaR) models and information criteria. Instead of using a single CAViaR model, we propose to utilize several candidate CAViaR models during a forecasting period. By adopting the Akaike and Bayesian information criteria for quantile regression, we can update not only parameter estimates but also the CAViaR specifications. We also propose extended CAViaR models with a constant location parameter. An empirical study is provided to examine the performance of the proposed method. The results suggest that our method shows more stable performance than those using a single specification.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2451-2453
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• 2002

In this paper, we present an infrared sensors aided map building method for mobile robot using genetic algorithm and fuzzy logic. Existing Bayesian update model using ultrasonic sensors only has a problem of the quality of map being degraded in the wall with irregularity which is caused by the wide beam width of sonar waves and Gaussian probability distribution. In order to solve this problem we propose an improved method of map building using supplementary infrared sensors. In the method, wide beam width of sonar waves is divided by infrared sensors and probability is distributed according to infrared sensors' information using fuzzy logic and genetic algorithm.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2000년도 추계정기학술대회:지능형기술과 CRM
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• pp.369-374
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• 2000

Despite their tilde application of some traditional project management techniques like the Program Evaluation and Review Technique, they lack of learning, one of important factors in many disciplines today due to a static view far prefect progression. This study proposes a framework for estimation by learning based on a Linear Bayesian approach. As a project progresses, we sequentially observe the durations of completed activities. By reflecting this newly available information to update the distribution of remaining activity durations and thus project duration, we can implement a decision support system that updates e.g. the expected project completion time as well as the probabilities of completing the project within talc due date and by a certain date. By Implementing such customized systems, project manager can be aware of changing project status more effectively and better revise resource allocation plans.

• 지능정보연구
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• 제6권2호
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• pp.91-98
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• 2000

Despite their wide application of some traditional project management techniques like the Program Evaluation and Review Technique, they lack of learning, one of important factors in many disciplines today, due to a static view for project progression. This study proposes a framework for estimation by loaming based on a Linear Bayesian approach. As a project Progresses, we sequentially observe the durations of completed activities. By reflecting this newly available information to update the distribution of remaining activity durations and thus project duration, we can implement a decision support system that updates e.g., the expected project completion time as well as the probabilities of completing the project within the due bate and by a certain date. By implementing such customized system, project manager can be aware of changing project status more effectively and better revise resource allocation plans.

• 한국전산구조공학회논문집
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• 제26권2호
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• pp.139-146
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• 2013

본 논문에서는 페러데이 법칙을 이용한 진동발전 장치를 지하철의 자갈도상과 콘크리트 도상의 분류에 따른 기전력 량을 분석 하였다. 지하철 2호선 서초~방배 구간의 자갈도상에서 콘크리트 도상 변경으로 동일한 전동차 운행속도로 동일 구간에서 차량운행에 의한 동특성을 분석하고 진동력발전 장치를 이용해 얻어질 수 있는 기전력 량을 분석하였다. 또한 페러데이의 법칙에 의한 유도 기전력 식에 의한 계산 기전력 량과 발전 장치에 의한 관측 기전력 량을 베이지안 회귀 분석 및 상관분석을 통하여 철도에 적용되는 모델에 대한 신뢰구간과 모델식을 각 도상별로 업데이팅하였다. 수정된 식을 이용한 기전력은 한 개의 진동발전 장치 당 콘크리트 도상에서 4mV, 자갈도상에서는 40mV의 전력을 얻을 수 있다.

• Structural Monitoring and Maintenance
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• 제6권3호
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• pp.219-235
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• 2019

Scheduled inspections of common crossings are one of the main cost drivers of railway maintenance. Prognostics and health management (PHM) approach and modern monitoring means offer many possibilities in the optimization of inspections and maintenance. The present paper deals with data driven prognosis of the common crossing remaining useful life (RUL) that is based on an inertial monitoring system. The problem of scheduled inspections system for common crossings is outlined and analysed. The proposed analysis of inertial signals with the maximal overlap discrete wavelet packet transform (MODWPT) and Shannon entropy (SE) estimates enable to extract the spectral features. The relevant features for the acceleration components are selected with application of Lasso (Least absolute shrinkage and selection operator) regularization. The features are fused with time domain information about the longitudinal position of wheels impact and train velocities by multivariate regression. The fused structural health (SH) indicator has a significant correlation to the lifetime of crossing. The RUL prognosis is performed on the linear degradation stochastic model with recursive Bayesian update. Prognosis testing metrics show the promising results for common crossing inspection scheduling improvement.

• 한국전자통신학회논문지
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• 제8권6호
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• pp.805-814
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• 2013

본 논문에서는 손목 부착형 카메라의 시점불변 특성을 이용하여 조명 변화에 강인한 손 영역 추출 방법을 제안하고, 추출된 손 영역 정보를 이용하여 손 모양을 인식하는 시스템을 다룬다. 손목 부착형 카메라 장치는 물리적으로 시점불변의 영상을 제공하는 장점이 있으며, 본 논문은 이러한 특성을 적극 활용하여 적응형 히스토그램을 기반으로 베이지안 규칙을 사용하여 손 영역을 추출한다. 사전에 구축된 RGB 히스토그램으로부터 HSV 히스토그램을 생성하고, 현재의 영상으로부터 추출된 손 영역 정보를 이용하여 HSV 히스토그램을 갱신한다. 또한, 사용자 독립모델(User independent model)과 사용자 종속모델(User dependent model)의 장점을 고려하여 사용자가 사용함에 따라 사용자 독립모델에서 사용자 종속모델로 수렴하는 사용자 적응 방법을 제안한다. 제안하는 방법의 인식 성능을 평가하기 위해 16개의 지문자에 대한 인식률을 측정하여 27.91%의 인식률 증가 결과를 얻을 수 있었다.