• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.47
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• pp.47-55
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• 1998

This paper proposes a maintenance model considering the Inherent availability of certain requirement and two types of failures, repairable or irrepairable. In this model, the system is replaced in time when it doesn't meet the inherent availability requirement despite of all repairable failures; Otherwise it is replaced by the first irrepairable failure. Assuming that the j-th failure is repairable with probability ${\alpha}_j$, minimal repairs are performed for repairable failures between replacements. We drive the expected cost rate through the application of NHPP(Non-Homogeneous Poisson Process) in order to determine the optimal number $n^*$. The model includes some previous studies as special cases.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.426-433
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• 2002

This paper deals with an offline routing problem, which can be used as an explicit routing procedure in MPLS(Multiprotocol Label Switching) network, for traffic engineering. This problem is formulated as an MIP(Mixed Integer Programming) with the objective function which is to minimize the sum of the maximum link utilization for load balancing (link utilization) and the routing cost. Constraints arc composed of link capacity restriction and demand requirement that has origin-destination pair, bandwidth requirement and hop restriction. The problem is proved to be NP-hard so that the Lagrangean relaxation method is applied to propose a Lagrangean heuristic. To test the effectiveness & efficiency of the proposed algorithm, computational experiments are performed with numerical instances. The experiment results show that the proposed algorithm solves the problem within a reasonable time.

• Proceedings of the Society of Korea Industrial and System Engineering Conference
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• 2002.05a
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• pp.139-149
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• 2002

This paper presents an approach to derive probability models for use in structural reliability studies. Two main points are made. First, that it is possible to translate engineering and physics knowledge into a requirement on the form of a probability model. And second, that making assumptions about a probability model for structural failure implies either explicit or hidden assumptions about material and structural properties. The work is foundational in nature, but is developed with explicit examples taken from planar and general stress problems, the von Mises failure criterion, and a modified Weibull distribution.

• Journal of Drive and Control
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• v.21 no.2
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• pp.44-52
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• 2024

In this study, we predicted PTO power requirements based on torque predicted by the discrete element method and the multi-body dynamics coupling method. Six different scenarios were simulated to predict PTO power requirements in different soil conditions. The first scenario was a tillage operation on cohesionless soil, and the field was modeled using the Hertz-Mindlin contact model. In the second through sixth scenarios, tillage operations were performed on viscous soils, and the field was represented by the Hertz-Mindlin + JKR model for cohesion. To check the influence of surface energy, a parameter to reproduce cohesion, on the power requirement, a simple regression analysis was performed. The significance and appropriateness of the regression model were checked and found to be acceptable. The study findings are expected to be used in design optimization studies of agricultural machinery by predicting power requirements using the discrete element method and the multi-body dynamics coupling method and analyzing the effect of soil cohesion on the power requirement.

• Journal of the Korea Safety Management & Science
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• v.19 no.1
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• pp.103-114
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• 2017

The objective of this study is to analyze the needs and determine the requirements of elder drivers for effectively using In-vehicle Information System (IVIS), by reducing cognitive and physical impact on this vulnerable group. The persona method was used to determine the relevant characteristics of older drivers. Task analysis was performed in order to obtain general interaction problems of the personas when using a common function of recent days IVIS. The results were classified in the different usability goals as general requirements, specific needs. This study suggest improvement directions in order to develop an elderly friendly IVIS; in addition, different usability metrics were suggested. In this way, elder drivers would easily interact with new powerful functions supplied by IVIS of modern cars; while improving safety and comfort of an rapidly aging society.

• Transactions of the KSME C: Technology and Education
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• v.1 no.2
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• pp.199-204
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• 2013

In this paper, a new system requirement management tool and its application on the Urban Transit Maglev Project were introduced. In most R&D projects on complexity system such as transportation system, Systems Engineering(SE) activities are included on each project, and SE teams are using commercial computer-based tools to perform the SE activities. Even though SE tools help to manage huge data and documents on engineering efficiently, but well-designed functions of SE tools which support SE activities are not sufficiently used on the whole process of system engineering. In order to computer-based SE tools are to be effectively used on project management, most engineers who takes engineering and coordination roles, at least sub-project managers should be familiar to the tool and could be easily use it, but usability of commercial SE tools are very difficult for normal engineers with no experience on SE activities and SE tools. To overcome this difficulty, we developed a new system requirement management tool considering each user's scenario on using engineering tools. The developed tool could not cover whole SE processes, but designed to perform requirement engineering such as system requirements(SRs) management, specification management, traceability management, SRs' verification activity management and so on. All the entities on SR database are inter-connected by pre-recognized traceabilities, so even non-specialists on SE can easily browse the database and find entities concern, and linked information such as interacted entities, legal or engineering constraints, coordination documents, status of development and verification and so on. Also functions for SR verification tools, TPM(Technical Performance Measure) tools, DB searching tools with traceability, and report generation tools are included on the system.

• Journal of the Korean Professional Engineers Association
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• v.13 no.3
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• pp.60-64
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• 1980

Top manager and factory manager in the small-medium industrial factory in Korea was conscious of industrial education training requirement more than past, it began the Saemaul movement in factory from 1974, and the 1st nation wide meeting of industrial Standardization & Quality control Movement from 1975, etc. It is that industrial education training through the influence of pan-industrial nation with program. Because it is non-system and unplanned that are a short period introduction of industrial education training operation. Now then they are received better apprecation through the information of the program ecommendation and consultancy of industrial education training from coordination with related professional agencies and goverment agency for small-medium industry promotion.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.81-82
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• 2016

본 논문에서는 미국의 분산전원 연계용 PCS에 적용되는 Grid Code인 IEEE1547 Amendment의 fault ride-through에 대해 기술한다. IEEE 1547은 2014년 Amendment가 발행되었으며, 전압/주파수에 대한 사고판단 능력이 업데이트 되어 fault ride-through의 범위가 변경되었다. 개정된 IEEE1547a의 기준을 분석하고, 이를 적용한 fault ride-through 기능을 PSIM 시뮬레이션을 통하여 검증하였다.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.44
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• pp.185-195
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• 1997

In this paper, research and applications of a knowledge-base system in scheduling are review. The method is based on the problem-solving techniques developed in artificial intelligent. The object of this paper is to enable the re-time rescheduling under dynamic environments. Developed to KBS(Knowledge-Based Scheduling) system in this paper, will based on expert system, and applicate to requirement of users effectively.

• Proceedings of the Korea Society of Design Studies Conference
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• 2004.10a
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• pp.190-191
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• 2004