• Journal of Communications and Networks
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• v.11 no.2
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• pp.134-147
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• 2009

Tracking and exploiting instantaneous spectrum opportunities are fundamental challenges in opportunistic spectrum access (OSA) in presence of the bursty traffic of primary users and the limited spectrum sensing capability of secondary users. In order to take advantage of the history of spectrum sensing and access decisions, a sequential decision framework is widely used to design optimal policies. However, many existing schemes, based on a partially observed Markov decision process (POMDP) framework, reveal that optimal policies are non-stationary in nature which renders them difficult to calculate and implement. Therefore, this work pursues stationary OSA policies, which are thereby efficient yet low-complexity, while still incorporating many practical factors, such as spectrum sensing errors and a priori unknown statistical spectrum knowledge. First, with an approximation on channel evolution, OSA is formulated in a multi-armed bandit (MAB) framework. As a result, the optimal policy is specified by the wellknown Gittins index rule, where the channel with the largest Gittins index is always selected. Then, closed-form formulas are derived for the Gittins indices with tunable approximation, and the design of a reinforcement learning algorithm is presented for calculating the Gittins indices, depending on whether the Markovian channel parameters are available a priori or not. Finally, the superiority of the scheme is presented via extensive experiments compared to other existing schemes in terms of the quality of policies and optimality.

• Journal of the Korea Safety Management & Science
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• v.12 no.4
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• pp.255-263
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• 2010

The research developes short-run standardized control charts(SSCC) and short-run acceptance control charts(SACC) under the various demand patterns. The demand patterns considered in this paper are three types such as high-variety and repetitive low-volume pattern, extremely-high-variety and nonrepetitive low-volume pattern, and high-variety and extremely-low-volume pattern. The short-run standardized control charts developed by extending the long-run ${\bar{x}}$-R, ${\bar{x}}$-s and I-MR charts have strengths for practioners to understand and use easily. Moreover, the short-range acceptance control charts developed in the study can be efficiently used through combining the functions of the inspection and control chart. The weighting schemes such as Shewhart, moving average (MA) and exponentially weighted moving average (EWMA) can be considered by the reliability of data sets. The two types according to the use of control chart are presented in the short-range standardized charts and acceptance control charts. Finally, process capability index(PCI) and process performance index(PPI) classified by the demand patterns are presented.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.4
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• pp.50-58
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• 2018

Process Capability ($C_{pk}$) is a representative measure of how well the producer manages dispersion and bias for the specifications needed by the consumer. This is expressed as a ratio of 6 times the natural tolerance to the specification. As the producer manages the dispersion small, the capacity index becomes higher. And it is classified into 5 grades according to the degree of management. It is a measure of the quality of processes used in most industrial fields. However, $C_{pk}$ is calculated by only reflecting the mean and dispersion of the process, there is a disadvantage that it can not give information about the economic loss caused by the inconsistency of the process with the target value. Overcoming these drawbacks, process capability indexes reflecting various types of loss functions such as $C_{pm}$, $C^+_{pm}$ and $C_{pl}$ have been developed. However, all of these previous studies have applied the limit to the consumer specification, which is based on the traditional and passive quality perception that the quality characteristic should exist within the limits of the consumer specification. In this study, we will develop 'Customer Satisfaction Quality Indicator (CSQI)' which is a quantitative indicator that can be fully evaluated when the manufacturer's specification limit, which is an aggressive quality strategy, is applied. This is expected to be useful decision information for both producers and consumers.

• Culinary science and hospitality research
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• v.12 no.1 s.28
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• pp.203-215
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• 2006

This study tried to develop an estimation model on the competitive power as a method to understand a practical index on the competitive power in order to improve the competitiveness of domestic bakery corporations and look into their internal structure. The results of the practical analysis are summarized below. First, eight critical success factors, which are considered important in competitive power in bakery corporations, were derived from preceding studies and an expert meeting. Second, this study performed a questionnaire with eight derived factors for bakery managers and employees. Seven critical success factors suitable for bakery corporations were chosen through validity and reliability tests. Third, this study performed an AHP(Analytic Hierarchy Process) analysis in order to establish preference according to each factor and weight. The importance of factor concerned with the competitive power of bakery corporations according to the result of weight analysis appeared in order of customer resources, personnel resources, corporate images, material resources and qualities, technical capability, financial factors and pliability(time).

• Korea-Australia Rheology Journal
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• v.21 no.4
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• pp.289-297
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• 2009

We numerically analyzed flow characteristics of the polymer melt in the screw equipment using a proper modeling and investigated design parameters which have influence on the mixing performance as the capability of the screw equipment. We considered the non-Newtonian and non-isothermal flow in a single rotor equipment to investigate the mixing performance with respect to screw dimensions as shape parameter of the single rotor equipment and screw speed as process parameter. We used Bird-Carreau-Yasuda model as a viscous model of the polymer melt and the particle tracking method to investigate the mixing performance in the screw equipment and considered four mixing performance indexes: residence time distribution, deformation rate, total strain and particle standard deviation as a new mixing performance index. We compared these indexes to determine design parameters and object function. On basis of the analysis results, we carried out the optimal design by using the response surface method and design of experiments. In conclusion, the differences of results between the optimal value and numerical analysis are about 5.0%.

• Proceedings of the Korean Reliability Society Conference
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• 2000.04a
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• pp.123-129
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• 2000

SPC is the quality improvement technique of gathering since Motorola of U.S.A. have used SPC technique as a statistical process control method for promoting 6-sigma quality improvement strategy in 1988. In Korea, small and medium-sized enterprises are needed building of a system for statistical production control . In the present study, the methods of building SPC system with a moderate cost using a graphic programs of easy-to-use and high flexibility for small and medium-sized enterprises were inquired. The SPC system which enables statistic marking (maximum, minimum, mean, standard deviation, process capability index) and graph marking (X-Y coordinates and histogram) using LabVIEW 5.0, the graphic program by National Instrument Co., Ltd. was implemented in this study.

• Journal of Korea Multimedia Society
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• v.7 no.5
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• pp.601-616
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• 2004

Information retrieval systems for structured documents provide multiple levels of retrieval capability by supporting structure-based queries. In order to process structure-based queries for structured documents, information for structural nesting relationship between elements and for element sequence must be maintained. This paper presents four index structures that can process various query types about structures such as structural relationships between elements or element occurrence order. The proposed algorithms are based on the concept of Global Document Instance Tree.

• Korean System Dynamics Review
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• v.13 no.1
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• pp.159-182
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• 2012

Strategic decision on the execution of national security improvement project is greatly important for the present and future national security. Though, the importance of strategic decision, decision making process has been executed under one-way thinking framework. This research provides a decision-making tool with make-or-buy approach for the national security improvement policy execution methods: foreign purchase and military R&D project, and, via simulation, confirms dynamic change of military capability index respect to change in ratio of foreign purchase and military R&D. A result shows that current ratio of foreign purchases and military R&D is insufficient for national security improvement policy goal. Applying the model from this research provides an appropriate ratio for short term and long term defense strategy and policy goal, and consequent result of increase in national security capability. Thus, this research model can be effectively utilized for national security improvement project.

• Knowledge Management Research
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• v.15 no.1
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• pp.65-84
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• 2014

Organization's innovation capability is strongly tied to its intellectual capital or knowledge utilization. Employees play a key role in generation of intellectual capital and utilization of knowledge in a firm. Thus, the importance of human resource management (HRM) system for enhancing competency of employees and facilitating knowledge sharing between employees is getting its significance. In this paper, we highlighted the effect of HRM implementation to explain the reason of performance differences among firms, adopting the same ideal HRM system. The successful implementation of HRM system as well as the contents of HRM system was critical to enhance firm performance through HRM system. To investigate the effect of HRM implementation on firm performance, we proposed the three components of HRM implementation (i.e.; TMT philosophy, HR department capability and communication) in perspective of sense making and sense giving theory. Then, we analyzed the moderating effect of HRM implementation on the high commitment HRM - firm performance relationship. Empirical results showed that each component of HRM implementation positively strengthened the relationship between high commitment HRM and firm performance. In addition, the composite index of HRM implementation calculated by average value of three components revealed more significant moderating effect between the two. Furthermore, We discussed the academical and practical implications, and suggested future research directions.

• Journal of Korean Society for Quality Management
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• v.49 no.2
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• pp.145-159
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• 2021

Purpose: A statistical similarity evaluation to compare pharmacokinetics(PK) profile data between nonclinical and clinical experiments has become a significant issue on many drug development processes. This study proposes a new similarity index by considering important parameters, such as the area under the curve(AUC) and the time-series profile of various PK data. Methods: In this study, a new profile similarity index(PSI) by using the concept of a process capability index(Cp) is proposed in order to investigate the most similar animal PK profile compared to the target(i.e., Human PK profile). The proposed PSI can be calculated geometric and arithmetic means of all short term similarity indices at all time points on time-series both animal and human PK data. Designed simulation approaches are demonstrated for a verification purpose. Results: Two different simulation studies are conducted by considering three variances(i.e., small, medium, and large variances) as well as three different characteristic types(smaller the better, larger the better, nominal the best). By using the proposed PSI, the most similar animal PK profile compare to the target human PK profile can be obtained in the simulation studies. In addition, a case study represents differentiated results compare to existing simple statistical analysis methods(i.e., root mean squared error and quality loss). Conclusion: The proposed PSI can effectively estimate the level of similarity between animal, human PK profiles. By using these PSI results, we can reduce the number of animal experiments because we only focus on the significant animal representing a high PSI value.