• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.1 no.1
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• pp.51-64
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• 2002

This paper analyzes performance measures of a Bluetooth_based mobile home network system. The home network system consists of terminals with Bluetooth interfaces, access points (AP), a home PC, and a gateway A mobile host in wireless terminals uses Mobile IP for supporting the mobility This paper considers four types of data traffic, which are new connection traffic, handoff traffic, Internet data traffic, and control data traffic and suggests a queueing system model of the home network system, where the AP and the home PC are modeled as M/G/1 with four priority queues and the gateway is modeled as M/G/1 with a single queue The generation rate and service time of individual traffic influence their performance measures. Based ell the suggested model, we propose the elapsed time of data traffic in terms of the number of cells, the number of Home PCs, arrival rates of four types of traffic and the service rates of AP/Home PCs/Gateway To analyze influences on the elapsed time with respect to arrival rate of four types of traffic, some examples are given.

• Journal of Communications and Networks
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• v.10 no.3
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• pp.301-307
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• 2008

In this paper, the impact of channel sensing methods to IEEE 802.15.4 under the interference of IEEE 802.11b are analyzed. Two different channel sensing methods, energy detection and carrier sense, are considered. An average transmission delay, a throughput, and a power drain rate are used as performance measures. Those performance measures of IEEE 802.15.4 under the interference of IEEE 802.11b are analyzed mathematically. The simulation results are shown to validate the analytic results.

• Journal of applied mathematics & informatics
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• v.26 no.5_6
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• pp.1021-1035
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• 2008

In this paper, we analyze an N-design call center with skill-based routing, in which one pool of agents handles two types of calls and another pool of agents handles only one type of calls. The approximate analysis is motivated by a computational complexity that has been observed in the direct stochastic approach and numerical method for finding performance measures. The workforce staffing policy is very important to the successful management of call centers. So the allocation scheduling of the agents can be considered as the optimization problem of the corresponding queueing system to the call center. We use a decomposition algorithm which divides the state space of the queueing system into the subspaces for the approximate analysis of the N-design call center with two different types of agents. We also represent some numerical examples and show the impact of the system parameters on the performance measures.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.2
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• pp.138-146
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• 2012

This paper studies the effect of information quality level and customer demand on performance measures in a supply chain. The information quality level compares 2 types, the information levels of a customer demand and a lead time. The customer demand process follows a general auto-correlated AR(1) process without seasonality. In the AR(1) process, ${\sigma}$ indicates the degree of demand fluctuation and ${\rho}$ means the trend of customer demand. ANOVA tests using a 5% significance level are performed in SPSS to examine significant performance changes among various cases.

• Journal of Korean Society for Quality Management
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• v.24 no.3
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• pp.1-18
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• 1996

The purpose of this study is to empirically examine the role of supplier relationships as a means of enhancement of quality. The model for this study consists of four groups of concepts - 1) goal of quality, as 2) measures of supplier relationships, supplier assistance and buyer supplier communication, 3) the level of automation and technology, as 4) measures of performance, reliability quality and performance quality. By statistical analysis, the results are as follows. First, the goal of quality positively influences the level of automation, technology, supplier assistance and supplier communication. Second, the level of technology has a positive effect on supplier assistance and supplier communication on the level of automation. Third, the level of automation and technology positively influence the reliability quality. Fourth, supplier assistance and buyer-supplier communication has a positive effect on the reliability and performance quality. These results reveal three paths of supplier relationships in systems for the enhancement of quality.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.10a
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• pp.8-12
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• 2004

In this study we consider a CONWIP system in which the processing times at each station follow a Coxian distribution and the demands for the finished products arrive according to a compound Poisson process. The demands that are not satisfied are backordered according to the number of demands that exist at their arrival instants. For this system we develop an approximation method to calculate order based performance measures such as the mean time of fulfilling a customer order and the mean number o: customer orders. For the analysis of the proposed CONWIP system, we model the CONWIP system as a closed queueing network with a synchronization station and analyze the closed queueing network using a product form approximation method. Numerical tests show that the approximation method provides fairly good estimation of the performance measures of interest.

• Journal of the Ergonomics Society of Korea
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• v.20 no.3
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• pp.47-60
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• 2001

The purpose of this paper is propose an analytical method for evaluating user satisfaction of Internet website and identifying casual relationships between user satisfaction of Internet website and performance measures as like revisit intention and complaints using the structural equation model (SEM). This paper is intended to identify critical evaluation factors of user satisfaction for Internet website to determine criteria for evaluating the website. and use the criteria to develop a SEM model for quantitatively evaluation of each factors effects of user preference. The SEM model used 5 latent variables for the evaluation factors of website user satisfaction and 2 latent variables for performance evaluation. 2 portal sites were evaluated to construct the SEM model. and 74 subjects participated the website evaluation using the walk-through and face-to face survey method. Analysis results showed that the SEM model was statistically significant for all the 2 websites evaluated.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.2
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• pp.89-96
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• 2010

This study explores the application of the analytic network process (ANP) approach for the evaluation of R&D projects with heterogeneous objectives. The ANP model in this study produced the final priorities of projects with respect to several performance measures when there are interdependencies between research objectives and performance measures. The paper provides value to practitioners by providing a generic model for R&D project evaluation. The ANP approach is tested against empirical data drawn from fourteen R&D projects under six different objective programs sponsored by the Korean government.

• Journal of the Ergonomics Society of Korea
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• v.25 no.3
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• pp.33-41
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• 2006

This study empirically evaluated performance and preference of Hangul entry methods of five mobile phones through questionnaire and experiments. The questionnaire study revealed that 67% of respondents have been using SMS(short message service) more than six times a day, and that Hangul entry method is the most inconvenient thing when inputting Hangul characters. An experiment was conducted for assessing five Hangul entry methods in view of performance of entry time and errors, and subjective measures of satisfaction and preference. The results showed that Hangul entry method significantly affect objective performances as well as subjective measures at α=0.05 or 0.01. This study, in which real mobile phones were used, presented contrary result in terms of Hangul entry time, compared to the existing studies based on the conceptual models of Fitts' law or Hick-Hyman law.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.425-434
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• 2001

In this paper we introduce a general framework for the modeling, analysis and costing of logistic networks including supply chains (SCs). The employed modeling notation, the so-called Process Chain paradigm, is specifically developed for the application field of logistic networks which includes SCs. We view SCs as discrete event dynamic systems (DEDS) and apply corresponding simulative techniques in order to derive performance measures of the Process Chain model under investigation. For this purpose Process Chain models are automatically transformed into the input language of the simulation tool HIT. Subsequently, a cost accounting model using the performance measures is applied to obtain costs which are actually subject of interest. The usefulness and applicability of the approach is illustrated by a typical supply chain example. We investigate the impact of an additional SC channel between a manufacturer and web-consumers on the overall supply chain costs.