• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.548-555
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• 2003

Customer satisfaction level is usually measured in terms of price, quality, customization, after-sale-service, product variety etc. Each finn sets up a distinctive production/marketing strategy to gain competitive advantage by prioritizing the customer satisfaction measures. The market differentiation strategy directly results in supply chain performance such as lead time, inventory, customer fill rate and market share. Product proliferation desirable in customization sense often conflicts the economies of scale effect in production side. This paper focuses the relationship between product variety and market share. Specifically, we investigate how introduction of new product affects the current market share, i.e.,) formation of customer preference and provide some insight into the optimal range of product variety.

• Journal of the Korean Operations Research and Management Science Society
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• v.29 no.1
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• pp.101-112
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• 2004

Customer satisfaction level is usually measured in terms of price, qualify, customization, after-sale-service, product variety etc. Each firm sets up a distinctive production/marketing strategy to gain competitive advantage by Prioritizing the customer satisfaction measures. The market differentiation strategy directly results in supply chain performance such as lead time, inventory, customer fill rate and market share. Product proliferation desirable in customization sense often conflicts the economies of scale effect in production side. This paper focuses the relationship between product variety and market share. Specifically, we investigate how introduction of new product affects the current market share, i.e., formation of customer preference and provide some insight into the optimal range of product variety.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.4
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• pp.1006-1025
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• 2012

Improving the quality of service in IP networks is a major challenge for real-time voice communications. In particular, packet arrival-delay variation, so-called "jitter," is one of the main factors that degrade the quality of voice in mobile devices with the voice-over Internet protocol (VoIP). To resolve this issue, a receiver-based enhanced timing recovery algorithm combined with active jitter estimation is proposed. The proposed algorithm copes with the effect of transmission jitter by expanding or compressing each packet according to the predicted network delay and variations. Additionally, the active network jitter estimation incorporates rapid detection of delay spikes and reacts to changes in network conditions. Extensive simulations have shown that the proposed algorithm delivers high voice quality by pursuing an optimal trade-off between average buffering delay and packet loss rate.

• Journal of Communications and Networks
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• v.17 no.3
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• pp.221-230
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• 2015

Rateless codes have been shown to be able to provide greater flexibility and efficiency than fixed-rate codes for multicast applications. In the following, we optimize rateless codes for unequal error protection (UEP) for multimedia multicasting to a set of heterogeneous users. The proposed designs have the objectives of providing either guaranteed or best-effort quality of service (QoS). A randomly interleaved rateless encoder is proposed whereby users only need to decode symbols up to their own QoS level. The proposed coder is optimized based on measured transmission properties of standardized raptor codes over wireless channels. It is shown that a guaranteed QoS problem formulation can be transformed into a convex optimization problem, yielding a globally optimal solution. Numerical results demonstrate that the proposed optimized random interleaved UEP rateless coder's performance compares favorably with that of other recently proposed UEP rateless codes.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.151-152
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• 2006

Multi-hop system has advantage of low power consumption, improved cell capacity, and enlarged service coverage. Most of previous researches show that multi-hop relaying beyond dual-hop relaying does not improve system performance significantly. This leads most researches are focused on dual-hop relaying system. In this paper, we propose an optimal boundary condition to support maximal data rate for fluctuation of traffic load in single cell dual-hop relay system.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.4
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• pp.425-434
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• 2002

Mobility of service users makes location update and paging (L/P) procedures indispensable features in mobile communication networks. Importance of optimizing the configuration of L/P areas has been increased by the growth of L/P related signaling. In this study, we deal with the L/P configuration which an LA (Location Area) may contain multiple PAs (Paging Areas). Given the network topology, L/P related parameters, and traffics generated by each cell, is provided the problem of finding optimal LA/PA configuration minimizing the amount of L/P related signaling. The optimization problem is solved using a simulated annealing, and detailed computational results are conducted to capture the effects of mobility, call arrival patterns and boundary crossing rate on the LA and PA configurations.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.482-484
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• 1995

This paper proposes an expert system with improved heuristics in order to enhence convergence rate to the optimal solution when an emergence problem occurrs in the automated large scale distribution system. These heurictics, which a re obtained from the line loss and load balancing change after a line section transferred, are newly adopted for the emergence problem.

• International journal of advanced smart convergence
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• v.12 no.4
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• pp.171-176
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• 2023

This study is about a speech recognition error correction system designed to detect and correct speech recognition errors before natural language processing to increase the success rate of intent analysis in natural language processing with optimal efficiency in various service domains. An encoder is constructed to embedded the correct speech token and one or more error speech tokens corresponding to the correct speech token so that they are all located in a dense vector space for each correct token with similar vector values. One or more utterance tokens within a preset Manhattan distance based on the correct utterance token in the dense vector space for each embedded correct utterance token are detected through an error detector, and the correct answer closest to the detected error utterance token is based on the Manhattan distance. Errors are corrected by extracting the utterance token as the correct answer.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.2
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• pp.579-603
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• 2018

In this paper we propose a QoS-enhanced intelligent stochastic optimal fair real-time packet scheduler, QUEST, for 4G LTE traffic in routers. The objective of this research is to maximize the system QoS subject to the constraint that the processor utilization is kept nearly at 100 percent. The QUEST has following unique advantages. First, it solves the challenging problem of starvation for low priority process - buffered streaming video and TCP based; second, it solves the major bottleneck of the scheduler Earliest Deadline First's failure at heavy loads. Finally, QUEST offers the benefit of arbitrarily pre-programming the process utilization ratio.Three classes of multimedia 4G LTE QCI traffic, conversational voice, live streaming video, buffered streaming video and TCP based applications have been considered. We analyse two most important QoS metrics, packet loss rate (PLR) and mean waiting time. All claims are supported by discrete event and Monte Carlo simulations. The simulation results show that the QUEST scheduler outperforms current state-of-the-art benchmark schedulers. The proposed scheduler offers 37 percent improvement in PLR and 23 percent improvement in mean waiting time over the best competing current scheduler Accuracy-aware EDF.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.1
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• pp.37-45
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• 2018

This study develops a model to estimate the economic life of the large-diameter water supply pipeline in Korea by supplementing existing methods used to perform similar calculations. To evaluate the developed methodology, the model was applied to the actual target area with the conveyance pipe in P waterworks. The application yielded an economic life computation of 39.7 years, considering the cost of damages, maintenance, and renewal of the pipeline. Based on a sensitivity analysis of the derived results, the most important factor influencing the economic life expectancy was the predicted failure rate. The methodology for estimating the economic life of the water supply pipeline proposed in this study is one of the core processes of basic waterworks facility management planning. Therefore, the methods and results proposed in this study may be applied to asset management planning for water service providers.