• Journal of Korean Society for Quality Management
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• v.42 no.1
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• pp.43-61
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• 2014

Purpose: This study identifies preventive measures for VOC management by analyzing the causes and effects of factors that contribute to high risk service failure using FMEA on KORAIL VOC data. Methods: Two research methods were used. First, a Risk Priority Number (RPN) was assigned to each KORAIL VOC based on Failure Mode and Effect Analysis (FMEA). Second, multiple regression analysis was run with RPN factors that include severity, occurrence, and detection as the independent variables and customer dissatisfaction as the dependent variable. Results: Multiple regression analysis showed that RPN factors including severity, occurrence, and detection had significantly positive relationship with customer dissatisfaction. Based on these results, an FMEA was performed on VOC categories with high RPN for railroad stations including platform, ticketing, ticket verification, parking, and escalator, and VOC categories with high RPN for trains including entrance doors, cafes, air quality, announcement, and ticket verification. Conclusion: This study has practical implications to service failure management. A priority order using FMEA was established for the list of customer dissatisfactions that should be addressed to actively manage service failure, and strategies for tackling this priority list are offered.

• Journal of Information Technology Services
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• v.14 no.4
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• pp.185-197
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• 2015

As the uncertainty of demand in B2B electronics market has increased, firms need a strong method to estimate the market demand. An accurate prediction on the market demand is crucial for a firm not to overproduce or underproduce its goods, which would influence the performance of the firm. However, it is complicated to estimate the demand in a B2B market, particularly for the private sector, because firms are very diverse in terms of size, industry, and types of business. This study proposes both qualitative and quantitative demand forecasting approaches for B2B PC products. Four different measures for predicting PC products in B2B market with consideration of the different PC uses-personal work, common work, promotion, and welfare-are developed as the qualitative model's input variables. These measures are verified by survey data collected from experts in 139 firms, and can be applied when individual firms estimate the demand of PC goods in a B2B market. As the quantitative approach, the multiple regression model is proposed and it includes variables of region, type of industry, and size of the firm. The regression model can be applied when the aggregated demand for overall domestic PC market needs to be estimated.

• Journal of the Korean Society of Safety
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• v.38 no.4
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• pp.23-31
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• 2023

Revising the Occupational Safety and Health Act led to enacting and revising related laws and systems, such as placing fire observers in hot workplaces. However, the operating standards in such cases are still ambiguous. Although fire accidents occur through multiple and multi-step factors, the hazards of fire accidents have been identified in this study as individual rather than interrelated factors. The aim has been to identify multiple factors of accidents, outlining fire and explosion accidents that recently occurred in the domestic manufacturing industry. First, major keywords were extracted through text mining. Then representative accident types were derived by combining the main keywords through the co-word network analysis to identify the hazards and their relationships. The representative fire accidents were identified as six types, and their major hazards were then addressed for improving safety measures using the identification of hazards in the "Risk Assessment" tool. It is found that various safety measures, such as professional fire observers' training and clear placement standards, are needed. This study will provide useful basic data for revising practical laws and guidelines for fire accident prevention, system supplementation, safety policy establishment, and future related research.

• Journal of the Korean Society for information Management
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• v.29 no.2
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• pp.193-204
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• 2012

The characteristics of citation and centrality measures in citation networks can be identified using multiple linear regression analyses. In this study, we examine the relationships between bibliometric indices and centrality measures in an article-level co-citation network to determine whether the linear model is the best fitting model and to suggest the necessity of data transformation in the analysis. 703 highly cited articles in Physics published in 2004 were sampled, and four indicators were developed as variables in this study: citation counts, degree centrality, closeness centrality, and betweenness centrality in the co-citation network. As a result, the relationship pattern between citation counts and degree centrality in a co-citation network fits a non-linear rather than linear model. Also, the relationship between degree and closeness centrality measures, or that between degree and betweenness centrality measures, can be better explained by non-linear models than by a linear model. It may be controversial, however, to choose non-linear models as the best-fitting for the relationship between closeness and betweenness centrality measures, as this result implies that data transformation may be a necessary step for inferential statistics.

• Journal of Korean Society of Forest Science
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• v.94 no.3 s.160
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• pp.197-204
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• 2005

This study was conducted to investigate the effect of tsunami which occurred in coastal area of the East Sea in Korea, the function of coastal forest for the reduction of tsunami's speed and energy, and the non-structural measures through the research data of tsunami in Japan. The results showed that tsunami which occurred in the East Sea in 1983 and 1993 reached coastal area of Korea one hour and fifty minutes later from Japan, and caused a loss of lives and property and flooding damage. If 60 m width of coastal forest was formed, the speed was decreased by 30%, the energy by 10%. Therefore, the width of coastal forest must be at least 60 m, of which the stand structure is the multiple-layered forest of mixed-forest, and the wave preventing measures have to be constructed together. In addition, non-structural measures as tsunami warning and survival strategies must be prepared.

• Phonetics and Speech Sciences
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• v.1 no.2
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• pp.43-49
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• 2009

Vocal polyps are benign phonotraumatic lesions which are traditionally treated using phonomicrosurgical techniques. In the case of hyperfunctional voice use, voice therapy is effective and results in voice improvement. However, the utility of voice therapy about vocal polyp is in great demand. The purpose of this study was to evaluate the effects of voice therapy in patients with vocal polyps. The authors reviewed the medical records of 193 patients with vocal nodules or vocal polyps, and 64 patients (31 nodules and 33 polyps) were enrolled. All of the subjects had received explanation of problems, vocal hygiene education, and been treated by the $SKMVTT^{(R)}$ (Seong-Tae Kim's multiple voice therapy technique) ranging from 4 to 16 sessions (mean: 8.6 sessions). All subjects were examined by perceptual assessment, acoustic and aerodynamic measures, and VRP (voice range profile). In perceptual assessment, patients with vocal nodules had more breathy and strained voices than the vocal polyp group. Both groups significantly reduced rough, breathy voice after voice therapy. Patients with vocal polyps had worse voice quality than patients with nodules in acoustic measures. Both groups showed reduced jitter and shimmer after voice therapy. In aerodynamic measures, MPT and Psub were increased, and MFR was reduced (p<.05). Participants' frequency range and intensity range were increased after voice therapy, but only frequency range resulted in a significant difference (p<.05). In conclusion, the therapeutic effect of voice therapy in patients with vocal nodules and polyps was demonstrated perceptually and acoustically. We can suggest that voice therapy, including advice, vocal hygiene, and $SKMVTT^{(R)}$ is a useful as an initial choice of treatment for patients with vocal polyps before considering a surgical approach.

• Communications for Statistical Applications and Methods
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• v.13 no.3
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• pp.719-732
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• 2006

A set of clustering algorithms with proper weight on the formulation of distance which extend to mixed numeric and multiple binary values is presented. A simple matching and Jaccard coefficients are used to measure similarity between objects for multiple binary attributes. Similarities are converted to dissimilarities between i th and j th objects. The performance of clustering algorithms with balancing weight on different similarity measures is demonstrated. Our experiments show that clustering algorithms with application of proper weight give competitive recovery level when a set of data with mixed numeric and multiple binary attributes is clustered.

• Journal of the military operations research society of Korea
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• v.17 no.1
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• pp.84-104
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• 1991

Up to the present, the evaluation measures in the production and inventory management have been studied under the pre-condition that the costs for major factors(e.g,. cost of carrying inventory, cost of demand shortage) are given easily, although in practice, it is difficult. The case in which multiple participants have a different viewpoints in production and inventory management has not been studied, in spite of its frequent occurrence. This study suggests a production and inventory model with multiple objectives corresponding to major factors and the related interactive algorithm based on the preference structures of participants. The problem can be solved through a weighting vector generated by an interaction with participants. The concept of equity is also used in order to guarantee the reasonable distribution of group utility in determining the individual relative weights of participants. This study includes the reality of the model and the decision process in the production and inventory management.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1221-1226
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• 2015

This paper proposes a multiple switch mode power supply (SMPS) system based on the wireless network which controls variable load. The system enables power supply of up to 600W using 200W SMPS as a unit module and provides a controlling function of output power based on variable load and a monitoring function based on wireless network. The controlling function for output power measures the variation of output power and facilitates efficient power supply by controlling output power based on the measured variation value. The monitoring function guarantees a stable power supply by observing the multiple SMPS system in real time via wireless network. The performance of the proposed system was examined by various experiments. In addition, it was verified through standardized test of Korea Testing Certification. The results were given and discussed.

• Journal of Korean Institute of Industrial Engineers
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• v.17 no.2
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• pp.87-95
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• 1991

The exact solution of the closed queueing networks(CQN) is known only for the product form (BCMP) queueing networks. Various computational algorithms are available to derive system throughput(the rate at which a system completes units of computational work) of the networks. However, the computational expense of an exact solution is often excessive when there are multiple classes of cutomers. Instead of computing the exact values, it may be sufficient to derive bounds on the performance measures. Techniques for obtaining bounds on BCMP queueing networks have appeared in the past years. This paper also presents bounds on throughput in CQN models with multiple classes of customers.