• 한국통신학회논문지
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• 제28권9A호
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• pp.684-693
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• 2003

본 논문에서는 시변 패킷 기반 무선 링크에서 메시지와 패킷의 전송 지연 시간을 분석하였다. 메시지는 베르누이(Bernoulli) 프로세스에 따라 도착하고 생성되는 메시지의 길이는 지수 분포를 가진다고 가정하였다. 또한 시간 변이성을 가지는 무선 링크의 특성을 반영하기 위하여 2-상태 마코프 모델을 사용하여 해석하였다. 이 마코프 모델로부터, 패킷의 도착율과 패킷 전송 서비스 시간, 무선 링크의 평균 PER(packet error rate)의 항으로 패킷의 평균 전송 지연 시간과 평균 큐 길이를 해석적으로 분석하였고, 이러한 패킷의 성능 지표들로부터 메시지의 전송지연 시간 및 큐 길이를 유도하였다. 수치적 결과로부터 시변 패킷 기반 무선 링크의 안정적 동작과 전송 성능을 보장하기 위해서는 PER에 따라 메시지 도착율 및 길이가 제한되어야 한다는 것을 알 수 있었다. 또한 성능에는 각 상태의 머무는 시간보다 PER의 영향이 큼을 알 수 있었다.

• 제어로봇시스템학회논문지
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• 제22권4호
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• pp.293-300
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• 2016

The Voice recognition is one of convenient methods to communicate between human and robots. This study proposes a speech recognition method using speech recognizers based on Hidden Markov Model (HMM) with a combination of techniques to enhance a biped robot control. In the past, Artificial Neural Networks (ANN) and Dynamic Time Wrapping (DTW) were used, however, currently they are less commonly applied to speech recognition systems. This Research confirms that the HMM, an accepted high-performance technique, can be successfully employed to model speech signals. High recognition accuracy can be obtained by using HMMs. Apart from speech modeling techniques, multiple feature extraction methods have been studied to find speech stresses caused by emotions and the environment to improve speech recognition rates. The procedure consisted of 2 parts: one is recognizing robot commands using multiple HMM recognizers, and the other is sending recognized commands to control a robot. In this paper, a practical voice recognition system which can recognize a lot of task commands is proposed. The proposed system consists of a general purpose microprocessor and a useful voice recognition processor which can recognize a limited number of voice patterns. By simulation and experiment, it was illustrated the reliability of voice recognition rates for application of the manufacturing process.

• 대한원격탐사학회지
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• 제15권2호
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• pp.147-158
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• 1999

지표면에 대한 다양한 정보를 제공해 주는 원격탐사기법은 수 십년 동안 우리의 환경을 관찰하고 이해하는데 중요한 역할을 해왔다. 이러한 원격탐사 자료를 이용하는데 다양한 디지털 영상처리기법이 도입되어 자료에서 관찰되는 여러 가지 특성을 모형화하고 처리하는데 매우 유용하게 활용되어져 왔다. 화소들 간의 공간적 관계를 고려하는 Markov Random Field (MRF) 모형은 텍스처 모델링이나 영상분할 및 분류와 같은 여러 분야에서 많이 이용되는 모형으로 이것에 기초한 다양한 알고리즘이 발표되었다. 보통 원격탐사 자료는 그 크기가 매우 크고 시간적 간격을 두고 변화를 관측해 가는 경우에는 분석해야할 자료의 양이 매우 방대하다. 이러한 자료를 처리하는데 걸리는 시간은 처리해야할 자료의 양과는 비선형적 관계에 있다. 본 논문에서는 MRF를 이용하여 원격탐사 자료를 처리할 때 걸리는 시간을 단축하기 위한 방법론이 연구되었다. 이를 위해 논리적 구조로 영상을 피라미드형태로 감소하는 크기로 분석하는 multiresolution 구조가 고려되었는데 이는 연상의 거시적 특징과 미세한 특징을 효율적으로 분석할 수 있는 방법을 제공해 준다. 영상의 크기가 커질수록 파라미터 추정 또한 복잡하고 많은 시간을 요하게 된다. 본 논문에서는 이를 위해 Bayesian 방법을 이용하여 원격탐사 영상과 같은 크기가 큰 영상의 MRF 모형의 파라미터를 효율적으로 추정할 수 있는 방법에 제안되어 있다.

• 한국대기환경학회지
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• 제19권4호
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• pp.397-414
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• 2003

The performance of one-particle stochastic Lagrangian models for passive tracer dispersion are evaluated against measurements in horizontally-homogeneous neutrally-stratified atmospheric surface layer. State-of-the-technology models as well as classical Langevin models, all in class of well mixed models are numerically implemented for inter-model comparison study. Model results (far-downstream asymptotic behavior and vertical profiles of the time averaged concentrations, concentration fluxes, and concentration fluctuations) are compared with the reported measurements. The results are: 1) the far-downstream asymptotic trends of all models except Reynolds model agree well with Garger and Zhukov's measurements. 2) profiles of the average concentrations and vertical concentration fluxes by all models except Reynolds model show good agreement with Raupach and Legg's experimental data. Reynolds model produces horizontal concentration flux profiles most close to measurements, yet all other models fail severely. 3) With temporally correlated emissions, one-particle models seems to simulate fairly the concentration fluctuations induced by plume meandering, when the statistical random noises are removed from the calculated concentration fluctuations. Analytical expression for the statistical random noise of one-particle model is presented. This study finds no indication that recent models of most delicate theoretical background are superior to the simple Langevin model in accuracy and numerical performance at well.

• Journal of Information Processing Systems
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• 제13권4호
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• pp.951-969
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• 2017

In this paper, we newly propose a traffic information service model that collects traffic information sensed by an individual vehicle in real time by using a smart device, and which enables drivers to share traffic information on all roads in real time using an application installed on a smart device. In particular, when the driver requests traffic information for a specific area, the proposed driver-personalized service model provides him/her with traffic information on the driving directions in advance by predicting the driving directions of the vehicle based on the learning of the driving records of each driver. To do this, we propose a traffic information management model to process and manage in real time a large amount of online-generated traffic information and traffic information requests generated by each vehicle. We also propose a road node-based indexing technique to efficiently store and manage location-based traffic information provided by each vehicle. Finally, we propose a driving learning and prediction model based on the hidden Markov model to predict the driving directions of each driver based on the driver's driving records. We analyze the traffic information processing performance of the proposed model and the accuracy of the driving prediction model using traffic information collected from actual driving vehicles for the entire area of Seoul, as well as driving records and experimental data.

• 품질경영학회지
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• 제32권4호
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• pp.169-183
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• 2004

The synthetic control chart (SCC) proposed by Wu and Spedding (2000) is to detect shifts in the process mean. The performance was re-evaluated by Davis and Woodall (2002), and the steady-state average run length (ARL) performance was shown to be inferior to cumulative sum (CUSUM) or exponentially weighted moving average (EWMA) chart This paper proposes a simple adaptive scheme to improve the performance of the synthetic control chart. That is, once a non-conforming (NC) sample occurs, we investigate the next L-consecutive samples with larger sample sizes and shorter sampling intervals. We employ a Markov chain model to derive the ARL and the average time to s19na1 (ATS). We also propose a statistical design procedure for determining decision variables. Comprehensive comparative study shows that the proposed control chart is uniformly superior to the original SCC or double sampling (DS) Χ chart and comparable to the EWMA chart in ATS performance.

• 대한산업공학회지
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• 제39권5호
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• pp.440-449
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• 2013

We consider a reverse supply chain with a production facility and a recovery facility, and address the joint control of production and disposal decisions for sustainable operations. Demands are satisfied from on-hand inventory of serviceable products, replenished via manufacturing or remanufacturing. Sold products may be returned after usage and each returned product is disposed of or accepted for recovery. Accepted returned products are converted into serviceable products after remanufacturing process. Formulating the model as a Markov decision process, we characterized the structure of the optimal production and disposal policy as two monotone switching curves under a special condition. Three types of heuristic policies are presented and their performance is numerically compared.

• Journal of the Korean Data and Information Science Society
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• 제18권2호
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• pp.489-506
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• 2007

Gene structure prediction, which is to predict protein coding regions in a given nucleotide sequence, is the most important process in annotating genes and greatly affects gene analysis and genome annotation. As eukaryotic genes have more complicated structures in DNA sequences than those of prokaryotic genes, analysis programs for eukaryotic gene structure prediction have more diverse and more complicated computational models. There are Ab Initio method, Similarity-based method, and Ensemble method for gene prediction method for eukaryotic genes. Each Method use various algorithms. This paper introduce how to predict genes using HMM(Hidden Markov Model) algorithm and present the process of gene prediction with well-known gene prediction programs.

• 품질경영학회지
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• 제38권2호
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• pp.190-201
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• 2010

This research proposes a method for designing VSI (Variable Sampling Interval) control charts with supplementary run rules. The basic idea is to apply various run rules and the VSI scheme to a control chart in order to increase the sensitivity. The sampling process of the VSI run rules chart is constructed by Markov chain approach. A procedure for designing the VSI run rules chart is proposed based on Lorenzen and Vance's model. Sensitivity study shows that the VSI run rules charts outperform the FSI (Fixed Sampling Interval) run rules charts for wide range of process mean shifts. A major advantage of the VSI run rules chart over other charts such as CUSUM, EWMA, and adaptive charts is it's simplicity in implementation. Some useful guidelines are proposed based on the sensitivity study.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3595-3603
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• 2022

Nuclear safety-class DCS is used for nuclear reactor protection function, which is one of the key facilities to ensure nuclear power plant safety, the maintenance for DCS to keep system in a high reliability is significant. In this paper, Nuclear safety-class DCS system developed by the Nuclear Power Institute of China is investigated, the model of reliability estimation considering nuclear power plant emergency trip control process is carried out using Markov transfer process. According to the System-Subgroup-Module hierarchical iteration calculation, the evolution curve of failure probability is established, and the preventive maintenance optimization strategy is constructed combining reliability numerical calculation and periodic overhaul interval of nuclear power plant, which could provide a quantitative basis for the maintenance decision of DCS system.