• 한국콘텐츠학회논문지
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• 제5권1호
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• pp.147-155
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• 2005

본 논문에서는 음성과 동영상을 포함한 멀티미디어 시스템의 통신 채널에 대한 모델링과 성능분석을 수행한다. 음성과 동영상에 적합한 서로 다른 도착 처리 과정을 고려한 멀티미디어 패킷의 입력 트래픽 특성, 통신 채널의 동적 할당 방법, 가용 채널 부족시 데이터 패킷의 큐잉 허용과 제한 시간 경과시의 패킷 손실 처리, 큐잉을 허용하지 않으나 가드 채널을 갖는 음성 패킷의 채널 처리 방식 등을 모델링하고 가용채널 부족시 서비스를 받지 못하는 차단 확률과 큐에서 지정시간 경과시 손실되는 패킷 손실률 등의 성능 지표에 대한 수치결과를 분석한다. 이를 위하여 멀티미디어 시스템 통신 채널 SRN 모델을 개발한다. 본 논문에서 제시한 SRN 모델링 기법은 성능분석을 위하여 필요한 마르코프 체인의 복잡한 해석적 분석 대신 보상 개념에 의한 손쉬운 성능분석 방법을 보여준다.

• International Journal of Contents
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• 제12권4호
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• pp.31-44
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• 2016

Knowledge creation and management are regarded as critical success factors for an organization's survival in the knowledge era. As a process of knowledge acquisition and sharing, organizational learning mechanisms (OLMs) guide the learning function of organizations represented by its different learning activities. We examined a variety of learning processes that constitute OLMs. In this study, we aimed to capture the process and framework of OLMs and knowledge sharing and acquisition. Factors facilitating OLMs were investigated at three levels: individual, group, and organizational. The concept of an OLM has received some attention in the field of organizational learning, however, the relationship among the factors generating OLMs has not been empirically tested. As part of the ongoing discussion, we attempted a systemic approach for OLMs. OLMs can be represented by factors that are inherent to the organization's system; therefore, prior to empirically testing the OLM generating factor(s), evaluation of its organizational integration is required to determine effective treatment of each factor. Thus, we developed a framework to manage knowledge and proposed a method to numerically evaluate factors influencing the OLMs. Specifically, composite importance (CI) of the Decision-Making Trial and Evaluation Laboratory (DEMATEL) method was applied to explore the interaction effect of these factors based on systemic approach. The augmented matrix thus generated is expected to serve as a stochastic matrix of an absorbing Markov chain.

• International Journal of Contents
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• 제10권3호
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• pp.17-25
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• 2014

In this paper, we describe an adaptive Markov chain Monte Carlo-based particle filter that effectively addresses real-time multi-face tracking on mobile platforms. Because traditional approaches based on a particle filter require an enormous number of particles, the processing time is high. This is a serious issue, especially on low performance devices such as mobile phones. To resolve this problem, we developed a tracker that includes a more sophisticated likelihood model to reduce the number of particles and maintain the identity of the tracked faces. In our proposed tracker, the number of particles is adjusted during the sampling process using an adaptive sampling scheme. The adaptive sampling scheme is designed based on the average acceptance ratio of sampled particles of each face. Moreover, a likelihood model based on color information is combined with corner features to improve the accuracy of the sample measurement. The proposed tracker applied on various videos confirmed a significant decrease in processing time compared to traditional approaches.

• 경영과학
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• 제31권2호
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• pp.1-13
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• 2014

In almost all of the organizations, the cost for acquiring and maintaining the inventory takes a considerable portion of the management budget, and thus a certain constraint is set upon the budget itself. The previous studies on inventory control for each item that aimed to improve the fill rate, backorder, and the expenditure on inventory are fitting for the commercially-operated SCM, but show some discrepancies when they are applied to the spare parts for repairing disabled systems. Therefore, many studies on systematic approach concept considering spare parts of various kinds simultaneously have been conducted to achieve effective performance for the inventory control at a lower cost, and primarily, METRIC series models can be named. However, the past studies were limited when dealing with the probability distributions for representing the situation on demand and transportation of the parts, with the (S-1, S) inventory control policy, and so on. To address these shortcomings, the Continuous Time Markov Chain (CTMC) model, which considers the phase-type distributions and the (s, Q) inventory control policies to best describe the real-world situations inclusively, is presented in this study. Additionally, by considering the cost versus the system availability, the optimization of the inventory level, based on this model, is also covered.

• 한국위성정보통신학회논문지
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• 제10권2호
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• pp.10-13
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• 2015

본 논문에서는 네트워크 에너지 하베스팅 효율 향상을 위한 새로운 사용자 정보 피드백 알고리즘을 제안한다. 제안된 알고리즘은 방사되는 에너지 대비 수신되는 하베스팅 에너지 양의 증가폭을 중요한 하베스팅 파라미터인 임계점 와 비교하고 에너지 하베스팅 유저를 결정하는데 중점을 둔다. 이 방법을 이용하면 비효율적으로 방사되는 에너지 낭비를 막아 전체 네트워크의 에너지 하베스팅 효율을 증가 시킨다. 본 논문의 실험결과는 사용자 피드백 알고리즘을 이용해서 계산된 네트워크 유저의 하베스팅 에너지 양의 증가폭을 임계점 =15%와 비교해서 에너지 하베스팅 유저를 결정했을 때 전체 네트워크의 에너지 하베스팅 효율이 가장 높게 증가한 다는 것을 입증하였다.

• 한국멀티미디어학회논문지
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• 제9권4호
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• pp.414-420
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• 2006

온라인 문자 인식 기술은 PDA, 타블릿 PC 등 많은 새로운 응용에서 사용되고 있으나, 인식 기술은 아직 이러한 첨단 도구들을 자연스럽게 이용하기에는 못 미치는 실정이다. 또한 최근 많이 사용되는 은닉 마르코프 모델(HMM)은 입력패턴을 전체 표준패턴과 비교함으로써 많은 기억장소와 계산량을 필요로 하는 단점을 지니고 있다. 따라서 본 논문에서는 더욱 효율적으로 온라인 문자 인식을 가능하게 하는 방법을 제안한다. 본 연구에서는 전처리 단계를 거쳐 학습 데이터와 인식 데이터의 체인코드를 생성하고, 인식 단계에서 입력 데이터에 주성분 분석(PCA) 기법을 적용하여 데이터의 차원을 줄여 문자를 인식한다. 제안하는 방법의 타당성은 실험을 통해서 검증한다.

• 한국수산과학회지
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• 제41권6호
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• pp.466-470
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• 2008

Microsatellite DNA markers were used to investigate the genetic diversity and population structure of Pacific abalone Haliotis discus hannai collected from six locations (Uljin, Ulsan, Daechon, Taean, Wando, and Yosu) where hatchery-produced abalone have been released intensively. There was no distinguishable difference in the observed and expected heterozygosities between the six populations and a cultured population. However, there was a difference in the number of alleles per locus: 12.8 for the cultured population and 13.8 to 15.8 for the six populations. The proportion of stocked abalone ranged from 41.1 to 92.7% for wild-caught populations with a decreasing tendency of alleles per locus for an increasing proportion of stocked abalone. A departure from Hardy-Weinberg equilibrium (HWE) assessed using the Markov chain procedure (P<0.05) was observed in the six populations and cultured population at loci Hdh145 and Hdh5l2. The pairwise Fst test (P<0.05) showed a significant difference between the Uljin and Ulsan populations and four remaining populations (Wando, Daechon, Yosu, and the cultured population), among which the Wando population differed less than the other three populations (Daechon, Yosu, and the cultured population).

• 한국통신학회논문지
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• 제37B권9호
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• pp.741-749
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• 2012

항해 중인 선박과 육상기지국간에 VHF 대역을 통해 다중-홉 데이터 통신을 수행하기 위해 애드-혹 자율 구성 TDMA (Ad Hoc Self-Organizing TDMA: ASO-TDMA) 방식이 제안된 바 있으며, 이를 통해 해로를 따라 넓은 영역에 걸쳐 항해 중인 선박들이 분산적으로 무선 자원을 공유하면서 다중-홉 애드-혹 네트워크를 구성할 수 있다. 본 논문에서는 마코프 체인 모델을 기반으로 ASO-TDMA 방식 매체접근제어 프로토콜의 평균 수율 성능을 분석한다. 또한, 모의실험을 통해 수학적 분석 결과를 검증하고, 각 홉 영역에서 부프레임의 크기와 선박의 수에 따라 수율을 최대화하기 위한 최적의 전송률이 존재함을 보인다.

• Communications for Statistical Applications and Methods
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• 제25권2호
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• pp.131-157
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• 2018

We propose a robust event date model to estimate the date of a target event by a combination of individual dates obtained from archaeological artifacts assumed to be contemporaneous. These dates are affected by errors of different types: laboratory and calibration curve errors, irreducible errors related to contaminations, and taphonomic disturbances, hence the possible presence of outliers. Modeling based on a hierarchical Bayesian statistical approach provides a simple way to automatically penalize outlying data without having to remove them from the dataset. Prior information on individual irreducible errors is introduced using a uniform shrinkage density with minimal assumptions about Bayesian parameters. We show that the event date model is more robust than models implemented in BCal or OxCal, although it generally yields less precise credibility intervals. The model is extended in the case of stratigraphic sequences that involve several events with temporal order constraints (relative dating), or with duration, hiatus constraints. Calculations are based on Markov chain Monte Carlo (MCMC) numerical techniques and can be performed using ChronoModel software which is freeware, open source and cross-platform. Features of the software are presented in Vibet et al. (ChronoModel v1.5 user's manual, 2016). We finally compare our prior on event dates implemented in the ChronoModel with the prior in BCal and OxCal which involves supplementary parameters defined as boundaries to phases or sequences.

• 천문학회보
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• 제41권2호
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• pp.62.2-62.2
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• 2016

We present a newly developed algorithm based on a Bayesian method for 2D tilted-ring analysis of disk galaxies which operates on velocity fields. Compared to the conventional ones based on a chi-squared minimisation procedure, this new Bayesian-based algorithm less suffers from local minima of the model parameters even with high multi-modality of their posterior distributions. Moreover, the Bayesian analysis implemented via Markov Chain Monte Carlo (MCMC) sampling only requires broad ranges of posterior distributions of the parameters, which makes the fitting procedure fully automated. This feature is essential for performing kinematic analysis of an unprecedented number of resolved galaxies from the upcoming Square Kilometre Array (SKA) pathfinders' galaxy surveys. A standalone code, the so-called '2D Bayesian Automated Tilted-ring fitter' (2DBAT) that implements the Bayesian fits of 2D tilted-ring models is developed for deriving rotation curves of galaxies that are at least marginally resolved (> 3 beams across the semi-major axis) and moderately inclined (20 < i < 70 degree). The main layout of 2DBAT and its performance test are discussed using sample galaxies from Australia Telescope Compact Array (ATCA) observations as well as artificial data cubes built based on representative rotation curves of intermediate-mass and massive spiral galaxies.