• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.950-955
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• 2004

In the manufacture of liquid crystal display devices, there is a strong demand for contactless glass plate handling devices that can manipulate a glass plate without contaminating or damaging it. To fulfill this requirement, an electrostatic transportation device for glass plates is proposed. This device can directly drive a glass plate and simultaneously provide contactless suspension by electrostatic forces. To accomplish these two functions, a feedback control strategy and the operational principle of an electrostatic induction motor are utilized. The stator possesses electrodes which exert electrostatic forces on the glass plate and are divided into a part responsible for suspension and one for transportation. To accomplish dynamic stability and a relatively fast suspension initiation time, the structure of the electrode for suspension possesses many boundaries over which potential differences are formed. In this paper, an electrode pattern suitable for the suspension of glass plates is described, followed by the structure of the transportation device and its operational principle. Experimental results show that the glass plate has been transported with a speed of approximately 25.6 mm/s while being suspended stably at a gap length of 0.3 mm.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.76-85
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• 2006

In the manufacture of liquid crystal display devices, there is a strong demand for contactless glass panel handling devices that can manipulate a glass panel without contaminating or damaging it. To fulfill this requirement, an electrostatic transportation device for glass panels is proposed. This device can directly drive a glass panel and simultaneously provide contactless suspension by electrostatic forces. To accomplish these two functions, a feedback control strategy and the operational principle of an electrostatic induction motor are utilized. The stator possesses electrodes which exert electrostatic farces on the glass panel and are divided into a part responsible for suspension and one for transportation. To accomplish dynamic stability and a relatively fast suspension initiation time, the structure of the electrode for suspension possesses many boundaries over which potential differences are formed. In this paper, an electrode pattern suitable for the suspension of glass panels is described, followed by the structure of the transportation device and its operational principle. Experimental results show that the glass panel has been transported with a speed of approximately 25.6 mm/s while being suspended stably at a gap length of 0.3 mm.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1051_1052
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• 2009

This paper deals with operational characteristic analysis of a single-phase PCS (Power Conditioning System) for PV (Photovoltaic) power generation system with AF (Active Filter) function. The theory of dq transformation has been applied to the control strategy of a single-phase PV power generation system to implement the AF function. Application of the virtual two-phase using phase-shift makes it possible to use the dq theory for the single-phase PV power generation system. The authors are sure that the proposed system is a very useful to compensate harmonics caused by nonlinear loads in a single-phase utility system. In this paper, not only a theoretical aspect of the single-phase PV-AF system is discussed, but also the DSP (Digital Signal Processor) based experiment results are presented to demonstrate the effectiveness of the single-phase PV-AF system.

• IE interfaces
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• v.16 no.2
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• pp.125-139
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• 2003

This paper reports an empirical study on assessment of R&D best practices. The principles of quality management and their tools such as best practices or benchmarking have been so prevailing in the operational process that the R&D management recently consider extensive use of them for their innovation process. However, characteristics of the two processes may be different each other. Are the principles or the tools that were effective in the operational field still going to be effective in the innovative field? In order to answer the question, we statistically examine how R&D best practices contribute to the innovative performance. Upon literature review on technological innovation, we present a R&D process model whereby we set forth research hypotheses. Using data from 66 successful R&D efforts carried out among Korean firms mostly between 1999-2001, regression analyses reveal that best practices used in most stages throughout the R&D process are found not to significantly contribute to the innovative performance. Only those in technology strategy and prototyping stages are proven effective for technical and commercial performance respectively. Interestingly, efforts in a problem solving and improvement stage are counterproductive in the case of the innovation process. Discussions on our empirical observations are presented followed by some managerial implications.

• Smart Structures and Systems
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• v.22 no.2
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• pp.139-150
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• 2018

A variable electromotive-force generator (VEG), which is a modified generator with an adjustable overlap between the rotor and the stator, is proposed to expand the operational range of a regular generator through a simple and robust active control strategy. It has a broad range of applications in hybrid vehicles, wind turbines, water turbines, and similar technologies. A mathematical model of the VEG is developed, and a novel prototype is designed and fabricated. The performance of the VEG with an active control system, which adjusts the overlap ratio based on the desired output power at different rotor speeds for a specific application, is theoretically and experimentally studied. The results show that reducing the overlap between the rotor and the stator of the generator results in reduced torque loss of the generator and an increased rotational speed of the generator rotor. A VEG can improve the fuel efficiency of hybrid vehicles; it can also expand operational ranges of wind turbines and water turbines and harness more power.

• Journal of Korean Society of Transportation
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• v.29 no.2
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• pp.7-14
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• 2011

This paper discusses operational technique and effectiveness of Variable Speed Limits system that is implemented to control the traffic-flow on the Naebu Expressway. As the first step of the analysis, traffic data collected from vehicle detectors are corrected and smoothed. Applying a pattern analysis technique to the traffic data, the weekday traffic is classified into four different groups, and median of each group is calculated. Using three state variables, i.e., diverted traffic volume, average density and average speed, the conditions of roadway segments are determined. Computational outputs resulted from the application of the proposed model to the scenarios show that implementation of Variable Speed Limits system improved both safety and efficiency of the expressway. For the operational strategy, this paper also presents the change rate of the speed limit, and the effective duration of the speed limit according to the entering traffic volume.

• Journal of Korean Society on Water Environment
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• v.23 no.1
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• pp.103-110
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• 2007

An efficient operational strategy using expert system for metro water supply systems in case of emergency situations is developed in this study. The emergency situations of the water supply systems are classified into three categories : pipeline system accident, machinery and electric facility accident and water quality accident. A PC-based expert system is developed using CLIPS for Seoul metro water supply system, Phase 1 & 2 system and Phase 3 & 4 system. Broad professional knowledges and experiences from the experts in the water supply systems have been collected systematically to construct the knowledge base. Decision-making in case of an emergency is based upon the professional knowledge so that a rational and efficient operational management can be available even in the absence of experienced expert. Especially the expert model developed in this study also provides a guide for pumping operation in case of pipeline accident to confirm that the proper pressure to all nodes in the system is supplied. The pipe network simulator KYPIPE has been consecutively executed by trial and error fashion for each pipeline in the system. The results from KYPIPE were included in the knowledge base to supplement the knowledge of the field engineers.

• East Asian Journal of Business Economics (EAJBE)
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• v.6 no.4
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• pp.1-12
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• 2018

Purpose - This paper tests the effect of the structure of manufacturing and marketing subsidiary network on FX exposure of Korean MNEs. Furthermore, the moderating effect of pass-through ability on the relationship between the subsidiary network and FX exposure is explored. Research design and methodology - This study utilizes a sample of 309 Korean MNEs constructed from database offered by KOTRA and KIS-VALUE. Results - As operational flexibility arising from having operations in multiple locations provides an option for firms to tackle FX exposure, greater breadth of manufacturing subsidiary network reduces FX exposure, and greater depth increases FX exposure. However, both the breadth and depth of marketing subsidiary network decrease FX exposure due to the firm's higher level of market presence and knowledge to devise an appropriate marketing strategy that can buffer adverse exchange rate movement. Such an effect is intensified when MNE's have FX exposure pass-through ability stemming from differentiated good. Conclusions - Empirical findings suggest that types and structure of Korean MNEs' foreign subsidiary network are closely related to the level of FX exposure they are experiencing. Also, they can utilize marketing subsidiary network more efficiently when having a higher R&D intensity.

• Korea Journal of Hospital Management
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• v.25 no.3
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• pp.53-66
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• 2020

This study is aimed at investigated and compared the differences in the affect of hospital specialization according to hospital size using claims data of the Health Insurance and Review Assessment National Inpatient Sample in 2018 for diseases of the musculoskeletal system and connective tissue. To this end, we used multivariate hierarchical linear models(a.k.a., multi-level models) using two-tier data from 106,599 patients discharged after diseases of the musculoskeletal system and connective tissue from 734 hospitals. Multivariate results indicate that patients who were discharged with diseases of the musculoskeletal system and connective tissue from specialized hospitals with 200 beds or less stayed shorter and paid less inpatient charge than those who were discharged from less specialized hospitals. But for hospitals with 201-300 beds, no positive impact relationship was found between hospital specialization and operational performance. This finding may be limited evidence that the affect of a hospital's specialization strategy may vary depending on the size of the hospital. We discussed several managerial and health policy implications below.

• Journal of Korean Society for Quality Management
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• v.37 no.4
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• pp.61-70
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• 2009

This paper introduces quantitative tools for evaluating the relative efficiency of Career & Counseling Jobs in universities. As tools, it uses Data Envelopment Analysis (DEA) developed by Charnes and Cooper. It finally selects 29 DMUs which are listed on the Ministry Of Education, Science And Technology(http://academyinfo.go.kr). We measures the technical efficiency of each DMU with the use of DEA-CRS, rather then DEA-VRS because DEA-CRS not only compares relative efficiencies but also implicitly considers economies of scale based on the assumption of linearity. We run a linear programming model Frontier Analyst Program for the estimation of the relative efficiencies of each DMU. The model also indicates the precise amount of inefficiencies for each input, which mean how much inputs are wasted for a given output and how much the university is inefficiently operated. This analysis helps to give guideline for the organization to construct a futureoriented operational strategy and also to show clear picture of contents of mismanagement for the past. The details of mismanagement are to be identified, analysed and finally corrected.