• Communications for Statistical Applications and Methods
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• v.3 no.2
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• pp.77-83
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• 1996

This paper is concerned with an estimation problem for the AR(1) process $Y_t, t=0, {\pm}1, {\cdots}$with time carying autoregressive coefficient, where coefficient itself is also stochastic process. Attention is directed to the problem of finding a consistent estimator of ${\Phi}$, the mean level of autoregressive coefficient. The asymptotic distribution of the resulting consistent estimator of ${\Phi}$, is them discussed. We do not assume any time series model for the time varying autoregressive coefficient.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.530-534
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• 2002

This paper show serial communication method in order to design how to interface between fault tolerant systems with redundancy. Problem has been in the method that fault tolerant system had switched of serial data with common switching device. This problem degrade reliability in itself and total system which is interfaced with that serial communication system. So Arbitration module of serial communication which is suggested in this paper can improve the reliability using voter algorithm which fault is detected passively.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1991.10a
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• pp.357-365
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• 1991

Military material-supply problem is one of the most important logistic problems under conscription system. Formally, two approaches were followed lowed to this problem. (1) Needs for material per soldier is estimated by past experience. The total demand for the material is estimated by multiplication of this coefficient and the number of soldiers given in the governmental programme. (2) The total demand for the material is estimated by the forcast based on the past statistics. The material supply system based on these estimates, however, relies too much on past statistics ;lack of flexibility is feared to adapt itself to changes in conscription programme, life-time of materials and so on. In this paper, the author has followed new approach : The conscription system itself is a linear input-output system, in which sequences of enlistment and dischargement are regarded as input and output. And the sequencial demands for the material are related by another linear transformation to the former sequences. In this regard z-transformation is applied to construct to transfer functions associated with this system. With these transfer functions, methods are established to determine the material demand corresponding to conscription programme and life-time distribution. Numerical methods by computers are also prepared.

• Management Science and Financial Engineering
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• v.12 no.2
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• pp.37-62
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• 2006

This paper considers the problem of designing logical tunnels in virtual private networks considering QoS guarantee which restricts the number of tunnel hops for each traffic routing. The previous researches focused on the design of logical tunnel itself and Steiner-tree based solution algorithms were proposed. However, we show that for some objective settings it is not sufficient and is necessary to consider both physical and logical connectivity at the same time. Thereupon, the concept of the layered network is applied to the logical tunnel design problem in virtual private networks. The layered network approach considers the design of logical tunnel as well as its physical routing and we propose a modified branch-and-price algorithm which is known to solve layered network design problems effectively. To show the performance of the proposed algorithm, computational experiments have been done and the results show that the proposed algorithm solves the given problem efficiently and effectively.

• Journal of Agricultural Extension & Community Development
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• v.10 no.2
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• pp.239-249
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• 2003

Waste policy instruments such as garbage bag-fee system and recycling policy initiated in 1995 have contributed to the reduction of solid waste generation. Rural areas now produce less amount of solid wastes in terms of per capital than urban areas and as compare to a decade ago. However, most policy efforts since the early 1990s related to waste issue have been concentrated in urban areas. Waste problems in rural areas are not the amount itself, but the specific characteristics which are unique in rural regions. Large portion of solid wastes and farming wastes are being illegally treated and/or burned out. Surveys show that the main reasons for the illegal treatment of rural wastes are th lack of systematic policy tools targeting on them, insufficient financial capacity and man power of local governments, rural people's cognition problem about wastes, among others. This study reviews current features of the treatment of rural solid wastes and provides policy suggestions for the resolution of the problem.

• Journal of the Korean School Mathematics Society
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• v.14 no.4
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• pp.539-564
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• 2011

This study examined how elementary teachers perceive and use "problem-posing" as a way to improve students' problem-solving skills in their mathematics classrooms. In the study, a total of 193 teachers in metropolitan areas were surveyed and a subset of 4 teachers were selected for depth-interviews. Results of the study included that teachers did not have a clear understanding of the study included that teachers did not have a clear understanding of the intended meaning of "problem-posing" although many of them have heard about the idea itself. Therefore, "problem-posing" was not fully utilized in their mathematics instructional and assessment. It is suggested that there is a need to develop instructional materials and related professional development of teachers for better instruction of problem-posing in the mathematics classroom.

• ETRI Journal
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• v.18 no.1
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• pp.29-41
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• 1996

This paper describes a method to select a suitable feature for speech recognition using information theoretic measure. Conventional speech recognition systems heuristically choose a portion of frequency components, cepstrum, mel-cepstrum, energy, and their time differences of speech waveforms as their speech features. However, these systems never have good performance if the selected features are not suitable for speech recognition. Since the recognition rate is the only performance measure of speech recognition system, it is hard to judge how suitable the selected feature is. To solve this problem, it is essential to analyze the feature itself, and measure how good the feature itself is. Good speech features should contain all of the class-related information and as small amount of the class-irrelevant variation as possible. In this paper, we suggest a method to measure the class-related information and the amount of the class-irrelevant variation based on the Shannon's information theory. Using this method, we compare the mel-scaled FFT, cepstrum, mel-cepstrum, and wavelet features of the TIMIT speech data. The result shows that, among these features, the mel-scaled FFT is the best feature for speech recognition based on the proposed measure.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.241-245
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• 1989

A knowledge based expert system is a computer program that emulates the reasoning process of a human expert in a specific problem domain. This paper presents an expert system to diagnose the various faults in power system. The developed expert system is represented considering two points; the possibility of solution and the fast processing speed. As uncertainties exist in the facts and rules which comprise the knowledge base of the expert system, Certainty Factor, which is based on the confirmation theory is used for the inexact reasoning. Also, as the diagnosis problem requires the inductive reasoning process in nature, the solution is imperfect and not unique in general. So the expert system is designed to generate all the possible hypothesis in order of the possibility and also it can explain the propagation procedure of the faults for each solution using the built in backtracking mechanism. In realization of the expert system, the processing speed is greatly dependent upon the problem representation, reasoning scheme and search strategy. So, in this paper the fault diagnosis problem itself is analysed from the view point of Artificial Intelligence and as a result, the expert system has the following basic features. 1) The certainty factor is adopted in the inference engine for inexact reasoning. 2) Problem apace is represented using the problem reduction technique. 3) Bidirectional reasoning scheme is used. 4) Best first search strategy is adopted for rapid processing. The expert system was developed us ing PROLOG language.

• Industrial Engineering and Management Systems
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• v.12 no.3
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• pp.181-189
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• 2013

This paper proposes a two-phase genetic algorithm (GA) to solve the problem of obtaining an optimum configuration of a paired single row assembly line. We pair two single-row assembly lines due to the shared usage of several workstations, thus obtaining an optimum configuration by considering the material flow of the two rows simultaneously. The problem deals with assigning workstations to a sequence and selecting the best arrangement by looking at the length and width for each workstation. This can be considered as an enhancement of the single row facility layout problem (SRFLP), or the so-called paired SRFLP (PSRFLP). The objective of this PSRFLP is to find an optimal configuration that seeks to minimize the distance traveled by the material handler and even the use of the material handler itself if this is possible. Real-world applications of such a problem can be found for apparel, shoe, and other manual assembly lines. This research produces the schematic representation solution using the heuristic approach. The crossover and mutation will be utilized using the schematic representation solution to obtain the neighborhood solutions. The first phase of the GA result is recorded to get the best pair. Based on these best matched pairs, the second-phase GA can commence.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1077-1081
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• 1990

Autonomous action, which corresponds actively to the change of conditions in complicated circumstances, is a fundamental function required to an intelligent robot. To develope a control system for a robot having the ability to adapt itself to complicated circumstances, it is necessary to establish self-tracing technology, which recognizes the corresponding position between peripheral objects and itself. So we need to manipulate the moving system with flexibility. It is effective for solving problem that fuzzy theory is adapted to algorithm on a complicated circumstances. We develope a method to generate a route-map which has not only a course from the present position to the destination but also useful information on surroundings.