• Journal of Korean Society of Industrial and Systems Engineering
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• v.13 no.22
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• pp.17-24
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• 1990

The inventory problem of the repairable items is modeled as a queueing network for the purpose of determining the number of spares in a multi-echelon repair system subject to stochastic failure. In this paper, we are considering a finite number of repairman at each base and the depot. After repair job has completed, the repaired items are returned to the base where they have originated. For the system, we identify the distribution of the total number of failed items which belongs to a base and develope a method to find spare inventory levels of the repairable items at each base to satisfy a specified minimum fill rate.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.12
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• pp.4759-4775
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• 2015

The reduction of power consumption in large-scale datacenters is highly-dependent on the use of virtualization to consolidate multiple workloads. However, these consolidation strategies must also take into account additional important parameters such as performance, reliability, and profitability. Resolving these conflicting goals is often the major challenge encountered in the design of optimization strategies for cloud data centers. In this paper, we put forward a data center monitoring strategy which dynamically alters its approach depending on the cloud system's current state. Results show that our proposed scheme outperformed strategies which only focus on a single metric such as SLA-Awareness and Energy Efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.5
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• pp.976-998
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• 2011

This paper attempts to maximize the operator's revenue while simultaneously providing a multi-constraint, multi-hop and deterministic QoS provisioning for real time traffic in IEEE 802.16m based 4G networks. The optimal solution to such a problem is NP-complete and therefore not feasible to be solved in a tolerable polynomial time. For this reason, we also provide a simple price based greedy heuristic to be used along with the admission control. Simulation results for different QoS schemes show that the heuristic produces a revenue that is very close to the optimal revenue, and is far more aggressive than the size based and other common algorithms that are computationally feasible to be implemented in IEEE 802.16m.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.4
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• pp.30-44
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• 2003

In the microcell-or picocell-based system the frequent movements of mobiles bring about excessive traffics into the networks. A mobile location estimation mechanism can facilitate both efficient resource allocation and better QoS provisioning through handoff optimization. Existing location estimation schemes consider only LOS model and have poor performance in presence of multi-path and shadowing. In this paper we study novel schemes which can increase estimation accuracy by considering NLOS environment and other multiple decision parameters than the received signal strength.

• Journal of the military operations research society of Korea
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• v.24 no.2
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• pp.146-161
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• 1998

This article develops model of the nonstationary state behavior of the multiechelon spare parts provisioning systems. This study is concerned with a problem of determining the near optimal requirements level of the spare parts, especially Concurrent Spare Parts(CSP). CSP is supplied with the procurement of new equipment system, and is used to sustain the equipment without resupply during the initial coverage period. We consider this situation as a multiechelon inventory model with several bases and one depot. And we assume an equipment system which consists of many types of parts would grounded if one of the parts fail. Also this multiechelon CSP problem is considering the nonstationary poisson failure process and nonstationary exponential repair process in a dynamic environment. We develop an efficient computational procedure to find the near optimal number of spare parts minimizing the total expected cost, while achieving the required system availability. Finally we present a simple example of suggested method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3A
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• pp.225-230
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• 2010

In this paper, we propose a new power control scheme to maximize the network throughput with fairness provisioning. Based on the game model, decisions in the scheme cooperatively and collaborate with each other to satisfy efficiency and fairness requirements. The simulation results demonstrate that proposed scheme has excellent network performance, while other schemes cannot offer such an attractive performance balance.

• Journal of Communications and Networks
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• v.9 no.1
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• pp.84-92
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• 2007

This paper deals with the creation of multicast trees in a differentiated services (DiffServ) domain. Initially, we model the integration problems of multicast & DiffServ and give a general de-scription of our framework for multicast provisioning in DiffServ domains. Within this framework, we introduce a novel heuristic algorithm which calculates the multicast trees efficiently. The multicast tree's format and the bandwidth constraints per service class are modeled. The heuristic is based on the Dijkstra's shortest path algorithm and aims to produce the cheapest possible trees (Steiner tree problem) that conform to the defined model. The produced trees can be considered as DiffServ-customized Steiner trees. Furthermore, we evaluate the algorithm with theoretical and experimental analysis and finally, we present our conclusions.

• Proceedings of the Korea Contents Association Conference
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• 2017.05a
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• pp.501-502
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• 2017

사용자의 요구에 맞게 시스템 자원을 할당, 배치, 배포해 두었다가 필요시 시스템을 즉시 사용할 수 있는 상태로 미리 준비해 두는 Provisioning이 이슈가 되고 있다. 비용대비 효과, 컴퓨터 성능향상, 편리성과 효율성, 비즈니스 역량강화의 장점을 추구하는 클라우드 환경에서의 대학정보시스템 구축방향과 일치한다. 또한, 이미 구축한 On-Premise 시스템 기반에서 동일한 소프트웨어, 툴, 에코시스템 애플리케이션을 활용할 수 있도록 소프트웨어 일관성을 보장하며, 이를 통해 비즈니스 민첩성 및 데이터 주도적인 분석 통찰력을 향상시킬 수 있다. 하지만 캠퍼스 클라우드시스템 구현은 네트워크 고도화, 가상화 인프라 고도화, 보안 고도화라는 단계적 전략을 통해서만 완성할 수 있을 것이다.

• Journal of the Korean Operations Research and Management Science Society
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• v.18 no.2
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• pp.157-173
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• 1993

Reliability growth modeling can be a requirement when bidding on large military hardware systems. Under current reliability warranty legislature, the reliability growth model can be later translated into necessary reliability performance which must be demonstrated over an extended period of usage. In this paper the modeling situation is concerned with determining the number of spares needed to support a projected reliability growth both at the fightine and in a depot inventory. The model differs from existing models for logistics planning in that we allow for the phenomena of reliability growth. The model can also be used to determine central depot staffing requirements based upon a specified system utilization.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2003.11a
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• pp.55-65
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• 2003

Since 1990s, despite the emergence of innovative telecommunication services in accordance with technological changes, only few services have attained satisfactory number of subscribers, and create revenues. As with other products or services, the possibility for the success of new telecommunication services is low, thus a systematic business strategy by businesses is required to achieve market success with broadband wireless Internet. For the current broadband wireless Internet to successfully enter the early market with an early growth, a customer oriented market strategy and service provisioning strategy is inevitable. In this study based on the market survey of individuals and business customers, the customer demand and related needs of broadband wireless Internet have been analyzed in depth. Then with the analysis and establishment of the killer applications and market segmentation, market development strategy is proposed.