• 정보와 통신
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• 제31권6호
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• pp.3-11
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• 2014

Mobile operators today face yet another critical challenge as technology lifecycle becomes increasingly short and also as heterogeneous and complex network becomes exceedingly expensive and difficult to manage. With extremely competitive market and demanding users, the overall revenue structure is expected to get worse. A network architecture based on software-defined networking (SDN) and virtualization techniques gives operators greater opportunity to build cost-effective and efficient alternative to the legacy. In this work we review our Carrier Cloud as a future mobile network infrastructure that exploits both SDN and NFV in order to increase the operator agility, reduce the cost, and even disrupt the vendor landscape. This new architecture will not be fully adopted by the conservative operators at once. Technological hurdles have to be overcome, and a clear understanding of operational differences must be preceded.

• 한국신뢰성학회지:신뢰성응용연구
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• 제17권4호
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• pp.316-324
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• 2017

Purpose: The purpose of this study is to determine the replacement cycle applied age replacement policy by reliability analysis based on railway vehicle contactor's failure history data. Method: We performed reliability analysis based on railway vehicle contactor's failure history data. We found a suitable distribution by goodness of fit test and predicted the reliability through estimation of scale & shape parameter. Considering cost information we determined the replacement cycle that minimize the opportunity cost. Result: Suitable distribution was the Weibull and scale parameter & shape parameter are estimated by reliability analysis. The replacement cycle was predicted and MTTF, $B_6$ percentile life were suggested additionally. Conclusion: We confirmed that failure rate type of railway vehicle contactor is degradation model having a time dependent characteristic and examined the replacement cycle in our country's operating environment. We expect that this study result contribute to railway operation agency for maintenance policy decision.

• 예술인문사회 융합 멀티미디어 논문지
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• 제5권4호
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• pp.683-691
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• 2015

The purpose of this paper is to determine the actual strategies used in Inventory Management in the field of Distribution phenomenon. In the first part of the research, theoretical backgrounds will be reviewed in order to provide better understanding the importance of Inventory Management in Distribution Management. The qualitative data were gathered by face to face interviews and a phone interview from four selected intermediaries. The study finds intermediaries practicing JIT in the sales and distribution and maximizing the sales activities and minimizing the inventory cost by giving up on an opportunity cost.

• 한국콘텐츠학회논문지
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• 제18권2호
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• pp.188-199
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• 2018

본 연구의 목적은 네트워크 이론에 근거하여 기업인 네트워크 활동과 기업역량의 유형을 파악하고 이들 특성과 경영성과 사이의 영향 관계를 비교 분석하는 데 있다. 연구결과 기업인의 네트워크 빈도, 중요도, 신뢰도가 경영성과에 유의한 정(+)의 영향을 미쳤으며, 이때 기업역량(산업정보역량, 기회포착역량, 전략적 유연성, 거래비용절감)의 매개효과가 나타났다. 본 연구는 기업역량을 기업인 네트워크 활동의 직접적인 성과변수로 포함하여 경영성과의 측정을 시도하였으며, 기업인 네트워크 활동의 성과를 높이기 위해 네트워크 범위를 넓히기보다는 가장 중요한 네트워크 원천과의 교류에 집중하는 것이 바람직하며, 네트워크 활동의 질적 특성을 강화하기 위한 노력이 필요하다는 결론을 도출한 데 연구의 시사점이 있다.

• 한국품질경영학회:학술대회논문집
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• 한국품질경영학회 1998년도 The 12th Asia Quality Management Symposium* Total Quality Management for Restoring Competitiveness
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• pp.544-555
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• 1998

Although the bimodal mixed weibull distribution is used to developing burn-in model widely, the failure times for a component or a system is often truncated at some time, T, due to the obsolescence in the electronics industry. In this paper, we will determine minimum total cost and burn-in time by using the bimodal mixed weibull distribution and the truncated bimodal mixed weibull distribution under the free warranty policy. The results of this study are summarized as follows. First, when products or system is not repairable, the width of the change of burn-in time can be larger by ${\beta}_1,\;{\beta}_2$ Second, if burn-in time become longer, it will be impossible to consider the bum-in in a long time, and in this case, the burn-in time should be shorten by the acceleration burn-in. Third, in case that opportunity loss cost or repair cost is exceed the warranty cost, or the total cost of considering burn-in is larger than that of not considering burn-in, it is not existed burn-in time which makes total cost to minimize. Forth, the shorter life-cycle of product, the more burn-in times will be decreased and the cost in considering burn-in will be increased

• 한국실내디자인학회논문집
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• 제41호
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• pp.96-103
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• 2003

The historical separation between organization studies and architecture area created a design environment in which wort processes are evaluated separately from setting where they occur. The impact of separation has been parallel yet disconnected development in th two disciplines in which the advance in one arena have not precipitated advances in the other. This is the unfortunate loss as each discipline has the potential to contribute directly to the other. With the emergence of new economy the opportunity to realign the tow disciplines is once again presented as new ways of working have enhanced this opportunity. It is important to revisit the historical development of the tow disciplines and to discuss how the misalignment of their respective concerns contributed to the establishment of our current situation. What happened to create an environment in which organizations assume that one of their largest capital expenditures the cost of providing work spaces for employees is unrelated to their work process\ulcorner what recent developments offer opportunities to rectify this dilemma\ulcorner In this study it is presented a historical review of organization studies and architecture. Through examination of these areas across time it becomes quite apparent that it is now appropriate to pose new questions about organization and their architecture. The comparison of two parallel developments explains how the current design environment is separated from organization studies and offers compelling evidence for why it is important to revisit this separation in light of contemporary theories on collaborative work, organizational learning and communities of practice.

• KIEE International Transactions on Power Engineering
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• 제4A권4호
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• pp.262-267
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• 2004

With the advent of electric power systems moving from a vertically integrated structure to a deregulated environment, calculating reactive power service charges has become a new and challenging theme for market operators. This paper examines various methods for reactive power management adopted throughout various deregulated foreign and domestic markets and then proposes an innovative method to calculate reactive power service charges using a reactive power market in a wholesale electricity market. The reactive power market is operated based on bids from the generating sources and it settles on uniform prices by running the reactive OPF programs of the day-ahead electricity market. The proposed method takes into account recovering not only the costs of installed capacity but also the lost opportunity costs incurred by reducing active power output to increase reactive power production. Based on the result of the reactive OPF program, the generators that produce reactive power within the obligatory range do not make payments whereas the generators producing reactive power beyond the obligatory range receive compensation by the price determined in the market. A numerical sample study is carried out to illustrate the processes and appropriateness of the proposed method.

• Journal of Information Technology Applications and Management
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• 제21권4호
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• pp.97-125
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• 2014

This study investigates the relationship between stock index and its associated nearby futures markets based on the cost-of-carry model. The purpose of this study is to explore the existence of mispriced futures contracts, and to test whether traders can earn trading profits in real financial market using the information about the mispriced futures contracts. This study suggests the concordance correlation coefficient to investigate the existence of mispriced futures contracts. The concordance correlation coefficient gives a desirable result for trading profits that results from a comparative analysis among profits from trading at the time to indicate trading opportunities determined by the degree of the difference between the observed market price and the theoretical price of a futures contract. In addition, this study also explains that the concordance correlation coefficient developed from the mean square error (MSE) has a statistically theoretical meaning. In conclusion, this study shows that the concordance correlation coefficient is appropriate for analyzing the relationship between the observed stock index futures market price and the theoretical stock index futures price derived from the cost-of-carry model.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권10호
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• pp.4703-4723
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• 2016

The verification of data integrity is an urgent topic in remote data storage environments with the wide deployment of cloud data storage services. Many traditional verification algorithms focus on the block-oriented verification to resolve the dispute of dynamic data integrity between the data owners and the storage service providers. However, these algorithms scarcely pay attention to the data verification charge and the users' verification experience. The users more concern about the availability of accessed files rather than data blocks. Moreover, the data verification charge limits the number of checked data in each verification. Therefore, we propose a mixed verification protocol to verify the data integrity, which rapidly locates the corrupted files by the file-oriented verification, and then identifies the corrupted blocks in these files by the block-oriented verification. Theoretical analysis and simulation results demonstrate that the protocol reduces the cost of the metadata computation and transmission relative to the traditional block-oriented verification at the expense of little cost of additional file-oriented metadata computation and storage at the data owner. Both the opportunity of data extracted and the scope of suspicious data are optimized to improve the verification efficiency under the same verification cost.

• 정보처리학회논문지B
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• 제17B권5호
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• pp.389-398
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• 2010

차량 경로 스케줄링 문제(VRSPTW, the Vehicle Routing and Scheduling Problem with Time Window)는 여러 고객의 시간 제약과 요구량을 만족시키면서 최소 이동 비용을 가지는 경로를 구성하는 문제이다. 이 문제는 NP-Hard 문제이기 때문에 해를 산출하는데 시간이 오래 걸린다. 본 연구는 VRSPTW를 빠른 시간 내에 최근사해를 구하기 위한 멀티 비용 함수(Multi Cost Function)를 갖는 개미 군집 최적화(Ant Colony Optimization)을 이용한 휴리스틱을 제안하였다. 멀티 비용 함수는 각 개미가 다음 고객 노드로 이동하기 위해 비용을 평가할 때 거리, 요구량, 각도, 시간제약에 대해 서로 다른 가중치를 반영하여 우수한 초기 경로를 구할 수 있도록 한다. 본 연구의 실험결과에서 제안된 휴리스틱이 Solomon I1 휴리스틱과 기회시간이 반영된 하이브리드 휴리스틱보다 효율적으로 최근사 해를 얻을 수 있음을 보였다.