• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.59
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• pp.53-67
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• 2000

In this paper we consider the CSP requirements determination problem of new equipment(machine) system. For the newly procured equipment systems, mathematical analyses are made for the system which is constructed with the consumable parts and the repairable parts to derive the associated CSP requirement determination model in mathematical expression. Based on these analyses, a mathematical model Is derived for making an optimal CSP requirement determination subject to the constraint of satisfying any given operational availability limitation. We assume that the failure of a part follows a Poisson process and the repair time has an exponential distribution. Firstly, the operational availability concept in CSP is defined and the relation between the general system availability and the operational availability is established. Secondly, the problem is formulated as the cost minimization problem that should satisfy the operational availability limitation, and then, using the generalized Lagrange multipliers method, the optimal solution procedure Is derived.

• 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.

• 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.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.1
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• pp.97-104
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• 2005

Considered is the concurrent spare part(CSP) requirements problem of new equipment system. In the considered system, when a part fails, the part cannot be repaired and should be replaced. In addition, cannibalization is allowed. It is assumed that the failure of a part follows a Poisson process. The operational availability concept in CSP is defined, and a formula is derived to calculate the operational availability using expected machine operating time during CSP period. The problem is formulated as the operational availability maximization problem with available budget constraint and a heuristic solution search procedure is developed. An illustrative example is shown to explain the solution procedure.

• KNOM Review
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• v.22 no.3
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• pp.31-39
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• 2019

This paper introduces our research results of SDN/SON-based emergeny communications system for nuclear power plant under extreme natural diaster like Fukusima nuclear power plant incident. In such a extreme situation, nuclear power plant operational staffs which do not have technical knowledge of network provisioning and operations have to deploy the emergency network. Thus our proposed system provides capabilities to provision an emergency network autonomically and enable voice and data services. It also describes our PoC system developed based on the proposed core technology and architecture with the results of system verification testing.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.7
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• pp.2530-2547
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• 2015

In the recent years, femtocell technology has received a considerable attention due to the ability to provide an efficient indoor wireless coverage as well as enhanced capacity. However, under the spectrum sharing between femtocell user equipment (FUEs) and the owner of spectrum macrocell user equipment (MUEs), both may experience higher uplink interference to each other. This paper proposes a novel distributed power control algorithm for the interference management in two-tier femtocell networks. Due to the assignment of licensed radio frequency to the outdoor macrocell users, the access priority of MUEs should be higher than FUEs. In addition, the quality of service (QoS) of MUEs that is expressed in the target signal-to-interference-plus-noise ratio (SINR) must always be achieved. On the other hand, we consider an efficient QoS provisioning cost function for the low-tier FUEs. The proposed algorithm requires only local information and converges even in cases where the frontiers of available power serve the target SINRs impossible. The advantage of the algorithm is the ability to implement in a distributed manner. Simulation results show that the proposed algorithm based on our cost function provides effective resource allocation and substantial power saving as compared to the traditional algorithms.

• Journal of Communications and Networks
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• v.11 no.4
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• pp.375-383
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• 2009

The WiMedia alliance has specified a distributed medium access control (WiMedia MAC) protocol based on ultra wideband (UWB) for high data rate WPANs (HR-WPANs). The merits of WiMedia MAC such as distributed nature and high data rate make it a favorite candidate in HR-WPAN. Although QoS parameters such as the range of service rates are provided to a traffic stream, the WiMedia MAC is not able to use the QoS parameters and to determine or adjust a service rate using the QoS parameters for the traffic stream. In this paper, we propose a fair and adaptive resource allocation method that allocates time slots to isochronous streams according to QoS parameters and the current traffic load condition in a fully distributed manner. Although the traffic load condition changes, each device independently recognizes the changes and calculates fair and maximum allowable service rates for traffic streams. From the numerical and simulation results, it is proved that the proposed method achieves high capacity of traffic streams and fair QoS provisioning under various traffic load condition.

• The Journal of Industrial Distribution & Business
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• v.13 no.10
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• pp.15-22
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• 2022

Purpose: In the manufacturing sector, VDI (Virtual Desktop Infrastructure) offers advantages to the organizations, such as allowing manufacturers access to the system from any location. The most important things are understanding what the user needs, avoiding under-provisioning, network preparation. This research is to provide useful practical l implementations of VDI in manufacturing industry based on numerous prior studies. Research design, data and methodology: This research has conducted the qualitative content analysis (QCA). When conducting this research, the present author assumed that it is crucial to create the procedures and processes that will be used to acquire the text data needed to structure or solve problems. Results: According to the prior literature analysis, there are five suggestions to implement successful VDI for manufacturing sector. The five solutions are (1) Creation of the machines, (2) Direct users to an available 'Virtual Machine', (3) 'Virtual Machine Power Management', (4) Performance monitoring, and (5) Review security. Conclusions: The research clearly details how VDI can be implemented on a manufacturer platform and how it can be connected to hundreds of users. The author can conclude that connecting hundreds of users can be done using the remote connection of devices and encourage manufacturers to work from different areas.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.17 no.1
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• pp.305-324
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• 2006

The requirements to use high speed internet under wireless environment are increased. To satisfy the requirements. the WiBro service combining high speed of wired internet service with mobility of wireless internet service will be launched as an alternative. This paper reviews and analyzes its overview, features, and comparison with existing mobile internet and wireless LAN in the information providing aspect. This paper also proposes how to adapt mobile information service and how to satisfy the requirements to construct mobile library based on the WiBro service. With the current problems in mobile-based information services provided by libraries. especially this paper proposes information service areas. considerations to provide information services, and service provisioning method based on the WiBro service.

• Journal of Advanced Navigation Technology
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• v.14 no.4
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• pp.530-536
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• 2010

This paper proposes a QoS/QoE guaranteeing scheme by reassembling packets that have already been delivered to the end systems under the condition that there is no other way to fulfill user's QoS/QoE with the current network conditions. The proposed scheme is a QoS/QoE provisioning scheme that can be applied when IPTV streaming packets have not been consecutively received by the receiver. The receiving end system modifies the continuous counter field in the MPEG-2 Transport Stream and reassembles packets based on this information. In the simulation, broadcasting streaming environment has been implemented in order to verity the QoS/QoE performance of the proposed scheme under the good and poor network conditions.