• Journal of the Korean Data and Information Science Society
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• v.8 no.1
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• pp.85-89
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• 1997

In this paper, we consider a random replacement model with minimal repair, which is a generalization of the random replacement model introduced Lee and Lee(1994). It is assumed that a system is minimally repaired when it fails and replaced only when the accumulated operating time of the system exceeds a threshold time by a supervisor who arrives at the system for inspection according to Poisson process. Assigning the corresponding cost to the system, we obtain the expected long-run average cost per unit time and find the optimum values of the threshold time and the supervisor's inspection rate which minimize the average cost.

• Journal of the Korean Data and Information Science Society
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• v.23 no.6
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• pp.1195-1202
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• 2012

In this paper, we determine the expected total cost from the user's perspective for the replacement model with the extended warranty when minimal repair cost is a function of failure time. To do so, we define the extended warranty and assume the replacement model following the expiration of extended warranty from the user's perspective. Especially, we propose the criterion to buy the extended warranty and the numerical examples are presented to illustrate the purpose when the failure time of the system has a Weibull distribution.

• Asia pacific journal of information systems
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• v.13 no.2
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• pp.67-85
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• 2003

This study was conducted to analyze Korean companie's perception in IT investment cost-benefit analysis(CBA), and to see if various user group's perception is different. Literature was reviewed to classify and define variables in IT CBA, and questionnaire was distributed to CEOs, CIOs, IT managers, and general managers in Korean companies. Respondent's priority ranking in IT CBA was shown to be tangible benefit, direct cost/intangible benefit, and indirect cost/risk. Data analysis showed that Korean companie's actual practice in CBA was generally aligned with their perception. User group's(Executives vs. mangers, and IT managers vs. general managers) perception was not shown to be statistically different. Survey result also showed that IT CBA was not well practiced in the companies although respondents perceive the analysis very important. These findings suggest that more education and practical experience is needed for Korean companies to perform IT CBA.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.784-791
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• 2007

Most operational organization and railway authority which conduct scheduled maintenance(SM) have carried out the preventive maintenance(PM) based on the information provided from supplier and manufacturer of railway system. However these activities are far away from reality and low the efficiency, it is because an appropriate methods for system selection didn't take into account for improving maintenance efficiency. Therefore, the current SM tasks and maintenance activities lead to lots of spend on the cost and time. To solve the above problem, this thesis presents new approach methodology. This proposes the criteria for reliability centered maintenance(RCM) system selection through level of quantification of each parameter, i.e, frequency, severity and maintenance cost, etc. To do this, the field operation data and information of maintenance cost are essential. As applying this methodology, we can look forward to improving efficiency of PM/SM, and reducing cost.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.1
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• pp.135-158
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• 2018

High-Speed vehicles can be considered as multiple mobile nodes that move together in a large-scale mobile network. High-speed makes the time allowed for a mobile node to complete a handover procedure shorter and more frequently. Hence, several protocols are used to manage the mobility of mobile nodes such as Network Mobility (NEMO). However, there are still some problems such as high handover latency and packet loss. So efficient handover management is needed to meet Quality of Service (QoS) requirements for real-time applications. This paper utilizes the cross-layer seamless handover technique for network mobility presented in cellular networks. It extends this technique to propose QoS-aware NEMO protocol which considers QoS requirements for real-time applications. A novel analytical framework is developed to compare the performance of the proposed protocol with basic NEMO using cost functions for realistic city mobility model. The numerical results show that QoS-aware NEMO protocol improves the performance in terms of handover latency, packet delivery cost, location update cost, and total cost.

• Smart Media Journal
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• v.9 no.3
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• pp.116-121
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• 2020

Digital Information Display and KIOSK have a problem that initial introduction cost and maintenance cost due to the development cost of dedicated contents and installation cost are high due to the characteristics of the product. In order to solve these problems, We designed and implemented of voice transmission system using Open Source Hardware and Event based Non-Blocking I/O Algorithm.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.10-12
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• 2002

본 논문에서는 신뢰성 있는 소프트웨어 개발을 위한 위험분석 방법을 모색한다. 기존의 프로세스 능력 결정(PCD: Process Capability Determination)결과의 차이를 이용한 전체 위험결정 방법의 취약점을 보안하기 위해 MBASE(COCOMOII)I에서 제시하는 위험분석 방법을 이용한다. 이 과정에서 필수적으로 수행되어야 할 과제는 레벨의 MP(Management Practice)단위 속성과 cost driver를 매핑함으로써 개별 위험항목(risk item)을 얻는 것이다. SPICE 레벨4 단계를 예로 cost driver를 추출하고 rating 결과를 입력하여 위험요소의 우선순위를 결정하며, 결정된 위험 우선순위에 따라 위험을 제거할 경우 전체 위험이 급격히 감소되어 RE(Risk Exposure) 그래프의 하강 곡선을 따름을 증명하였다. 이러한 산정결과를 통해 레벨에 영향을 미치는 위험 속성 및 위험 제거시 전체위험의 감소율을 예상할 수 있다.

• Journal of Korea Society of Digital Industry and Information Management
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• v.4 no.2
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• pp.81-92
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• 2008

With the increasing prevalence of e-learning courses in human resource development of Enterprise, it is important to investigate which courses are better economic performance. In this study, we proposed the framework for the cost-benefit analysis of e-learning, and attempted to identify cost and benefits factors. In order to achieve the research goal, we firstly tries to analyze the current IT adoption performance framework and e-learning staged performance model. The methodology adopted in the research was mainly that relevant materials, literatures were collected and analyzed to draw a comprehensive picture of the current situation and problems.

• Journal of the Korea Society of Computer and Information
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• v.20 no.9
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• pp.81-86
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• 2015

This paper suggests heuristic algorithm with linear time complexity to decide the normal and optimal point at minimum loss/maximum profit maximum shortest scheduling problem with additional loss cost and bonus profit cost. This algorithm computes only the earliest ending time for each node. Therefore, this algorithm can be get the critical path and project duration within O(n) time complexity and reduces the five steps of critical path method to one step. The proposed algorithm can be show the result more visually than linear programming and critical path method. For real experimental data, the proposed algorithm obtains the same solution as linear programming more quickly.

• International Journal of Contents
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• v.7 no.2
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• pp.1-5
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• 2011

Allocation of computing resources is a crucial issue when dealing with a huge number of tasks to be completed according to a given deadline and cost constraints. The task scheduling to several resources (e.g. grid, cloud or a supercomputer) with different characteristics is not trivial, especially if a trade-off in terms of time and cost is considered. We propose an allocation approach able to fulfill the given requirements about time and cost through the use of optimizing techniques and an adaptive behavior. Simulated productions of tasks have been run in order to evaluate the characteristics of the proposed approach.