• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.488-493
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• 2001

In accordance with the tendance to construct high-rise apartment buildings, the transporting elevators tend to speed up to 90-105m／min and to drive more frequently. So, the problem of noise produced by the elevator operation has been treated as an important subject. In this research, the actual conditions of noise and vibration which generated and transmitted by the elevator operation in apartment buildings were measured and analysed. And the several noise and vibration control design which helps reduce noise were examined.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.465-468
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• 2002

Today large corporations are constructing distributed server environment. Many corporations are respectively operating Web server, FTP server, Mail server and DB server on heterogeneous operation. However, there is the problem that a manager must manage each server individually. In this paper, we present distributed FTP server for log mining system on ACE. Proposed log mining system is based upon ACE (Adaptive Communication Environment) framework and data mining techniques. This system provides a united operation with distributed FTP server.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.336-343
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• 2002

This paper describes the result of endurance test on the Sangju test track. The purpose of the test is to prove the endurance of the Korean EMU for the commercial operation. Test conditions are more severe than actual operation on the commercial line. But endurance test come to an end well without severe problem. Hereafter, Korean EMU will be applied the quality certification of railroad supplies as a testing vehicle and their components will be applied in a new line.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.287-297
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• 1997

This research is concerned with operation control problem for an automated manufacturing system which consists of two machine centers and a single automatic guided vehicle. The objective is to develop and evaluate heuristic scheduling procedures that minimize maximum completion time to be included travel time of AGV. A new heuristic algorithm is proposed and a numerical example illustrates the proposed algorithm. The heuristic algorithm is implemented for various cases by SLAM II. The results show that the proposed algorithm provides better solutions than the previous algorithms.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.27 no.4
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• pp.90-93
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• 2004

This paper is case study for ISO 9001/2000 quality management system certification of social welfare. We constructed quality management system for efficient operation for service quality improvement of welfare hall which is society welfare facilities. This paper evaluated operation actual conditions of "G" welfare hall which introduce and operates quality management system according to index of evaluate for society welfare hall and present improvement plan about effect and problem.

• Industrial Engineering and Management Systems
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• v.8 no.1
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• pp.22-28
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• 2009

We consider facility layout problems, where mn facility units are assigned into mn cells. These cells are arranged into a rectangular pattern with m rows and n columns. In order to solve this cell type facility layout problem, many approximation algorithms with improved local search methods were studied because it was quite difficult to find exact optimum of such problem in case of large size problem. In this paper, new algorithms based on Simulated Annealing (SA) method with two neighborhood generation methods are proposed. The new neighborhood generation method adopts the exchanging operation of facility units in accordance with adjacent preference. For evaluating the performance of the neighborhood generation method, three algorithms, previous SA algorithm with random 2-opt neighborhood generation method, the SA-based algorithm with the new neighborhood generation method (SA1) and the SA-based algorithm with probabilistic selection of random 2-opt and the new neighborhood generation method (SA2), are developed and compared by experiment of solving same example problem. In case of numeric examples with problem type 1 (the optimum layout is given), SA1 algorithm could find excellent layout than other algorithms. However, in case of problem type 2 (random-prepared and optimum-unknown problem), SA2 was excellent more than other algorithms.

• IE interfaces
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• v.20 no.2
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• pp.186-194
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• 2007

Recent deregulation of Korean electricity industry has made each power generation company pay more attention to maximizing its own profit instead of minimizing the overall system operation cost while guaranteeing system security. Electricity power generation problem is typically defined as the problem of determining both the on and off status and the power generation level of each generator under the given fuel constraints, which has been known as Profit-Based Unit Commitment (PBUC) problem. To solve the PBUC problem, the previous research mostly focused on devising Lagrangian Relaxation (LR) based heuristic algorithms due to the complexity of the problem and the nonlinearity of constraints and objectives. However, these heuristic approaches have been reported as less practical in real world applications since the computational run time is usually quite high and it may take a while to implement the devised heuristic algorithms as software applications. Especially when considering long-term planning problem which spans at least one year, the complexity becomes higher. Therefore, this paper proposes an explicit column generation algorithm using power generation patterns and the proposed algorithm is successfully applied to a Korean power generation company. The proposed scheme has a robust structure so that it is expected to extend general PBUC problems.

• Journal of the Korean School Mathematics Society
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• v.21 no.4
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• pp.303-326
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• 2018

Fraction has difficulties in learning because of the diversity of meanings, the ways of presenting contents and teaching methods in elementary school mathematics. Therefore, the various strategies of teaching of fraction concept is proposed as an alternative. The problem of equal sharing problem is that children can experience the concept of fractions naturally in the context of everyday distribution. Even before learning formal fractions, children can solve them in various ways based on their own experiences. The purpose of this study is to investigate the degree of problem solving and problem solving strategies for children in 2nd, 4th, and 6th grades in elementary school. As a result of the research, the percentage of correct answers increased as the grade increased, but the grade levels showed a difference depending on the numbers given to the problems. Also, there were differences in the problem solving strategies according to the grade levels. Also, according to the numbers presented in the problem, the percentage of correct answers was high in items that were easy to divide, and the percentage of correct answers was low in items that were difficult to divide. When children solved the problems, they were affected by the strategies they could use immediately according to the number presented in the problem, and their learning experiences were also affected.

• Journal of the Korean Society of Safety
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• v.35 no.1
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• pp.12-17
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• 2020

This paper analyzes functions of component parts of D-Urban Railway's door system along with operation obstacle risks on frequency(the number of occurrences/year) and severity(delay time/the number of occurrences). Based on this, the paper presents improvements and current system's problems after obstacle risks of EMU and door system are appled. The obstacle of door system causes corrosion of main parts such as DCU due to heat problem of operation environment, problems of maintenance methods and deterioration. DCUs on PCBs with more than 50% pattern corrosion cause problems. Even though the number of door system's obstacle occurrences for the last 5 years is 42, along with 104 minutes of operation obstacle, EMU operation obstacle risk is low(Level 1), which indicates there is limit in matrix of railway risks presented by the standard of railway safety management system. Therefore, it is necessary to have railway risk matrix suitable for the field. Finally, the paper deducts the obstacle risks through frequency and severity. Since 2017 when the risks of EMU and door system's obstacle, that of EMU has been 24(47% reduced) and that of door system has been average 9.5 per year(23% reduced).

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2135-2142
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• 2010

This paper studies the validity about a joint operation of neutral wire and overhead grounding wire in combined distribution systems. The overhead grounding wire and neutral wire are currently installed separately and grounded by common. However there is no any ineffectiveness or electrical problem in case of the proposed system, such system can be operated at real distribution system. Therefore this paper describes the suitability of a joint operation through lightning surge analysis on combined distribution systems. Lightning surge analysis is carried out by EMTP/ATPDraw to obtain the overvoltage of overhead line and underground cable in various conditions such as locations and current types of lightning stroke. Overvoltage gained by the analysis show that the insulation strength of the joint operation case is not stable compare with the current operation case.