• Journal of the Korean Society of Mechanical Technology
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• v.13 no.4
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• pp.157-164
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• 2011

Hybrid car can improve fuel efficiency using a power of motor that is generated during constant-speed or deceleration driving. The motor is located between engine and transmission. But, when voltage of main battery is low, fuel efficiency is low because the voltage can't run the motor. In this situation, this study observed fuel efficiency when using solar cell for assistance power. In order to verify a fuel consumption of hybrid car equipped solar cell for assistance power, the car was tested downtown driving. As hybrid car was equipped solar cell for assistance, fuel consumption was reduced 8.35 % at running air conditioner. And, at air conditioner doesn't work, fuel consumption was reduced 6.88 %. This point of view, CO2 is expected to reduce in similar proportion.

• Journal of the Korean Operations Research and Management Science Society
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• v.39 no.3
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• pp.23-40
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• 2014

This paper measures the operational efficiency of domestic online game companies and analyze its trends and patterns by using data envelopment analysis (DEA). DEA is a non-parametric approach to measuring the relative efficiency of decision-making units (DMUs) with multiple inputs and outputs. 14 online game companies are selected as DMUs and three inputs (number of employees, capital and asset) and three outputs (sales, operating profit and net profit) are selected as DEA variables. First, the output-oriented BCC model and super-efficiency model are employed to measure the static operational efficiency of the online game companies from 2003 to 2012. We also conduct the dynamic analysis with DEA window model to capture the trends of their operational efficiency influenced by internal and external environmental changes. The results are expected to provide fruitful implications for strategic decision making of online game companies and policy making for the online game industry.

• Journal of Korean Society for Quality Management
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• v.37 no.2
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• pp.1-11
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• 2009

Recently, many companies have been very interested in CRM(Customer Relationship Management). Most companies have been also considering the contact center as a key CRM channel, because it is a contact point between customers and companies. It turns out that the contact center handles over 70% of all customer-company interactions and the success or failure of a company can be determined by the customer satisfaction with contact center experiences. Despite of the strategic importance of the contact center, there has been few empirical study on the efficiency of contact center operations in the literature. One of the main purposes of this study is to evaluate the efficiency of contact centers so as to not only identify the current status of contact center operations, but also suggest ways to improve operational efficiency. For this purpose, we apply a non-parametric efficiency measurement method, DEA (Data Envelopment Analysis), to 57 domestic contact centers in order to compare their relative efficiency. It is expected that the measurement methods suggested in this study can be applied to various issues such as service KS certification, outsourcing service management, and the productivity analysis of service personnel.

• Journal of Information Technology Services
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• v.13 no.4
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• pp.65-78
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• 2014

In this study, I explored the causal relationship between acceptance attitudes and the expected effects of smart work. With the rapid development of smart technologies, lots of organizations try to innovate in the conventional working styles for maximizing organizational effectiveness and efficiency. Although many organizations wish to foster smart working environment, they don't have confidence in detailed action plans and effects from it. Therefore, this study that explores the causal relationship between acceptance attitudes and effects may have crucial meaning to organizations pursuing smart work. In this research empirically conducted by questionnaire survey, the acceptance attitudes as predictors and the expected effects of smart work as influenced variables were used. This research analyzed 118 collected data and multiple regression analysis. As a result of analysis, teleworking shows the positive relations to all of dependent variables. And others have a positive or negative influence on cognitive effects of smart work. Results of this study may give implications to organizations that want to implement smart work environment.

• Journal of the Korean Statistical Society
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• v.23 no.2
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• pp.403-420
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• 1994

An economic design of the $\bar{X}-R$ chart using variable sample size (VSS) scheme is proposed in this paper. In this design the sample size at each sampling time changes according to the values of the previous two sample statistics, sample mean and range. The VSS scheme uses large sample if the sample statistics appear near inside the control limits and smaller sample otherwise. The set of process parameters, such as the sampling interval, control limits and the sample sizes, are chosen to minimize the expected cost per hour. The efficiency of the VSS scheme is compared to the fixed sample size one for cases where there is multiple of assignable causes. Percent reductions of the expected cost in the VSS design are calculated for some given sets of cost parameters. It is shown that the VSS scheme improves the confidence of the procedure and performs statistically better in terms of the number of false alarms and the average time to signal, respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.293-296
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• 2004

The objective of this study was to decide the designing factor for remediaton of the contaminated site. The soil and ground-water samples were analyzed and hydro- geological characteristics was assayed for the survey of pollution level. Also air-permeability test and MPN(most probable number) test were conducted for selecting the designing factor. The contaminants were mainly found in north-west part of the site and were expected to move toward the south. Ex-situ technology was expected more useful than in-situ one with the results of air-permeability test saying that air permeability was relatively low. Additional microbes were expected for remediation efficiency because residual microbes were loosely populated. The choosing of the designing factor was requisite for remediation of contaminated site.

• Journal of Information Technology Applications and Management
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• v.21 no.1
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• pp.151-163
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• 2014

This paper explores the causal relationship between acceptance attitudes and expected effects of smart work. With the rapid development of smart technologies, lots of organizations try to innovate in the conventional working styles for maximizing organizational effectiveness and efficiency. Although many organizations wish to foster smart working environment, they don't have confidence in detailed action plans and effects from it. Therefore, this study that explores the causal relationship between acceptance attitudes and effects may have crucial meaning to organizations pursuing smart work. In this research empirically conducted by questionnaire survey, the acceptance attitudes as predictors and the expected effects of smart work as influenced variables were used. This research analyzed 118 collected data and multiple regression analysis. As a result of analysis, teleworking shows the positive relations to all of dependent variables. And others have a positive or negative influence on effects of smart work. Results of this study may give implications to organizations that want to implement smart work environment.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.4
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• pp.517-526
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• 1999

This paper deals with two economic optimal designs of constant-stress accelerated life test(ALT) where failure distribution follows one of location-scale family, i. e., exponential, Weibull, and lognormal distributions which have been ones of the popular choices of failure distributions. Two optimization criteria to develop ALT plans are the statistical efficiency per unit expected cost which consists of the fixed test cost, cost being proportional to the number of test units, and variable test cost depending on test period and stress level, and the expected loss which combines Taguchi's quadratic loss function and expected test cost. Optimum plan determines the low stress level, test units allocated to each stress, and censoring times at two stress levels under Type I censoring. The proposed ALT plans are illustrated with a numerical example and sensitivity analyses are conducted to study effects of pre-estimates of design parameters.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.4
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• pp.88-95
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• 2007

Korea is highly dependent on foreign countries for energy while at the same time having a high energy-consumption industrial structure. Therefore, logical improvements in energy use efficiency and nationwide energy saving are becoming more and more important in coping with the worldwidehigh oil prices and environmental issues such as listed in the Kyoto Protocol to the United Nations Framework Convention on Climate Change. Consequently, a study was conducted on the average annual load factor in domestic areas to set a reasonable and reliable technology standard plan for high-efficiency transformers. The average annual load factor in Korea was discovered to be 18.4[%] classified by industry. This factor is expected to be used in arranging a domestic standard for a minimum efficiency system for transformers, and in reviewing and supplementing the standard transformers plan for the High Energy-Efficiency Appliance Certification. The expected effect from the establishment of the technology standards plan for highly efficient transformers is the expansion of the manufacturing and distribution of highly efficient transformers that are suitable for domestic use. These will lead to electricity cost savings for users, strengthening the related industries' market competitive powers and the effective reduction of greenhouse gases on a national level by drastically reducing loss from transformers, which accounts for a large portion of the total electric supply losses.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.1
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• pp.48-55
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• 2021

The 3-coil magnetic resonance wireless power transmission system was analyzed using an equivalent circuit model, and the |S21| of the system was expressed as the equation of the Q of the three coils, the coupling coefficient k between the transmitting coil and the relay coil, the relay coil and the receiving coil. It is suggested that the maximum efficiency can be obtained when the relay coil is located in the center of the transmitting and the receiving coil. When the distance between the transmitting and the receiving coil is 30 cm and the two coils are aligned, maximum efficiency of 9 % is obtained with the relay coil centered between the coils. If the transmitting coil and the receiving coil are misaligned during a wireless charging of an electric vehicle, the efficiency is expected to decrease significantly compared to the aligned case. It is expected that the efficiency can be increased by using a relay coil and by rotating the coil.