• Journal of Korean Society of Transportation
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• v.23 no.5 s.83
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• pp.15-25
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• 2005

Using a stochastic cost frontier approach(SCFA), this paper annually estimates the efficiency and productivity with same data in the papers which analyze the efficiency and productivity using data envelopment analysis(DEA) to compare the results and suggest the political findings of raising the efficiency and productivity for three publicly-owned rail transit properties. the Seoul Subway Corporation (SSC), the Seoul Metropolitan Electrified Railways Sector of Korea National Railroad (SMESRS) and the Busan Urban Transit Authority (BUTA). The results show that the results of SCFA are higher than DEA for efficiency and lower for productivity in that DEA regards the stochastic error and measurement error as the inefficiency contrary to SFCA. But the political findings from these results appears to be similar as follows. First, the productivity of the three properties should be first improved by using existing technologies efficiently and then by introducing new ones. Second, the three properties should improve the technical efficiency through reducing input quantities to raise their efficiency. Finally, all the three components of the productivity such as productive efficiency change, technical change, and scale change should be considered to evaluate their productivity more correctly.

• Journal of the Korean Data and Information Science Society
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• v.26 no.1
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• pp.111-121
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• 2015

Until now, the operation of community welfare centers for people with disabilities has brought a positive or a generous awareness. Nevertheless, in order to obtain a wide range of welfare outcomes efficiently, the imperative step in rehabilitation researches is to determine whether reasonable and scientific services are being provided to people with disabilities in rehabilitation centers. The purpose of this study was to analyze efficiency and productivity of 176 community welfare centers for people with disabilities. As a result, average technical efficiency for community welfare centers for people with disabilities was 0.4488; pure technical efficiency and scale efficiency was 0.6040 and 0.7080, respectively. The major conclusions of this study were as follows. First, applying the technical efficiency analysis, DMU2, DMU3, DMU8, DMU9, DMU11, DMU13, DMU14 were shown above average. It seems to have a regard for political elements in accordance with the regional social and economic differences. Second, as a result of scale efficiency analysis, the inefficient community welfare centers for people with disabilities such as DMU1, DMU5, DMU12, DMU16 are required to improve the number of employees, revenue, facility area. Finally, this study is expected to be an effectiveness analysis and performance evaluation for the rehabilitation services.

• Proceedings of the KOR-KST Conference
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• 2007.11a
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• pp.87-96
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• 2007

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.109-110
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• 2009

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2007.11a
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• pp.108-109
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• 2007

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.254-254
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• 2017

• The Journal of the Korea Contents Association
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• v.6 no.7
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• pp.111-118
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• 2006

This paper aims at exploring the efficiencies of Big 3 Multiplexes(CGV, Lotte Cinema, and Megabox) in Korea over the 3 years between 2002 and 2004. For the Korean Film industry, the years 1998 over were a period of challenge and extreme transaction due to building of multiplex that began in 1998. This paper begins with the present state of film market and multiplexes in Korea and provides an overview of the reasons why Korea film industry have been sharply increased in customer growth. The purpose of this paper is to investigate the film industry competition power for multiplex according to the technical and scale efficiency scores of DEA(Data Envelopment Analysis) method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.502-505
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• 2006

Acoustic holography allows us to predict spatial pressure distribution on any surface of interest from measured hologram. It is noteworthy that the data size is so huge that it takes long time to calculate pressure field. Moreover the reconstructed pressure field is frequently too complicated to get what we want to know. One possible candidate is complex envelope. Complex envelope in time domain is well known and widely used in various engineering field. We have attempted to extend this method to space domain, so that we can have rather simple spatial pressure picture that provides information we need, for example, where sound sources are. First we start with the simplest case. We examine the complex envelope of a plane wave on both space and wave number domain. Then we extend to monopole case. Holographic reconstructed sound field on the monopole is processed according to what we propose. We demonstrate how this method provides better picture for analyzing the sound field.

• Computational Structural Engineering
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• v.5 no.3
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• pp.127-137
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• 1992

A method for nonstationary response analysis of an offshore guyed tower subjected to earthquake loading is presented. The nonstationarity of the earthquake excitation is modeled by imposing a time varying envelope function onto a stationary random model. By taking the envelope function and the auto-correlation function of ground acceleration in terms of complex exponential functions of time, an analytical procedure is developed for computing time varying variances of the tower response. Example analysis indicates that the maximum responses estimated by considering nonstationary effect properly are significantly less than those obtained by the conventional frequency domain analysis method based upon the stationary assumption.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.8
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• pp.693-700
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• 2007

We can predict spatial acoustic pressure distribution on the plane of interest by using acoustic holography. However, the information embedded in the distribution plot is usually much more than what we need: for example, source locations and their overall propagation pattern. One possible candidate to solve the problem is complex envelope analysis. Complex envelope analysis extracts slowly-varying envelope signal from a band signal. We have attempted to extend this method to space domain so that we can have spatial information that we need. We have to modulate two dimensional data for obtaining spatial envelope. Although spatial modulation basically follows the same concept that is used in time domain, the algorithm for the spatial modulation turns out to be different from temporal modulation. We briefly describe temporal complex envelope analysis and extend it to spatial envelope of 2-D acoustic field by introducing geometric transformation. In the end, the results of applying the spatial envelope to the holography are envisaged and verified.