• Health Policy and Management
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• v.23 no.2
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• pp.112-123
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• 2013

Background: Under the risk of financial sustainability of National Health Insurance, Korean government attempted a series of regulations over pharmaceutical prices. The first price-cut was implemented to the hyperlipidemial treatments, and the prices of statins were reduced on 15th, April in 2009. The purposes of this study are 1) to investigate the impact of this price-cut on pharmaceutical expenditure, and 2) to identify the factors associated with drug-switch among statins. Methods: Using the national patients sample data, this study conducted time series analysis on the expenditures, prices, and volumes of statin drugs. To understand the factors associated with drug-switch, the multinomial logit model was analyzed at the patients level. Results: The results of time series analysis demonstrated that the price-cut of hyperlipidemic medicines did not lead to the reduced expenditure, suggesting the increased volume was the major cause. The multinomial logit analysis identified the switch of healthcare provider as the significant factor that was highly associated with drug-switch, implying the physicians' preference was the major motivation of drug-switch. Conclusion: Without control of utilization, price regulation itself could not reduce pharmaceutical expenditure. This suggests that the pharmaceutical regulations should be implemented on the basis of understanding of provider behaviors. The findings of this study will form the first step for further empirical studies.

• The Transactions of the Korea Information Processing Society
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• v.4 no.2
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• pp.628-638
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• 1997

This paper describes an implementation of fault simulator that can switch level fault models such as transistor stuck-open and stuck-closed faults as well as stuck-at faults. It overcomes the limitation when only stuck-at faults are used in VLSI circuits. Signal flow of a transistor switch is bidirectional in its nature, but most of signal flows in a switch level circuits, about 95%, are in one direction. This fault simulator focuses on the way which changes a switch level circuit into a graph model with two directed edges. Two paths from Vdd to ground and from ground to directions. Logic simulation is performed along dominant signal flows. The switch level fault simulation estimates the dominant path by injecting switch-level fualts, and pattern vectors are used for faults simulation. Experimental results are shown to demonstrate correctness of the fault simulator.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4B
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• pp.162-169
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• 2005

Network traffic measurements show that the data traffic on packet switched networks has the self-similar features which is different from the traditional traffic models such as Poisson distribution or Markovian process model. Most of the call admission control researches have been done on the performance analysis of a single network switch. It is necessary to consider the performance analysis of the proposed admission control scheme under interconnected switch environment because the data traffic transmits through switches in networks. From the simulation results, it is shown that the call admission control scheme may not operate properly on the interconnected switch even though the scheme works well on a single switch. In this parer, we analyze the cell loss probability, utilization and self-similarity of output ports of the interconnected networks switch by using shared buffer memory management schemes and propose the new call admission control scheme considering the interconnected network switches under self-similar traffic environments.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.9
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• pp.146-155
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• 1994

In this paper, we desribe a new system, called BEST, that is used to develop a macromodel or behavioral model easily. It automatically calculates the component values of macromodel represented by equations to satisfy the given specification. Also, it gives the way to analyze both the behavioral model and transistor level circuit, and then compare the analysis results of them to check the correspondence under specific temperature and bias condition, and BEST optimizes the component values of macromodel. Other feature is to characterize MOSFET as switch model which consists of PWL-RC network. Finally, it is possible to generage multi-level netlist which consists of macro/switch/transistor level circuits, and user can determine the trade-off between simulation speed and accuracy. With the graphic user interface form of macromodel development system described above. BEST enable designers to make macromodel by themselves and to uas it. We applied BEST to develop the macromodel for the test circuit and got the 18.6 times simulation speed up with preserving the accuracy within 10% compared to the conventional transistor level circuit simulation. Also, applicability of optimization capability was verified.

• Journal of Korean Institute of Industrial Engineers
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• v.19 no.1
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• pp.47-59
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• 1993

Recently, Broadband ISDN(B-ISDN) has received increased attention as a communication architecture which can support multimedia applications. Also, Asynchronous Transfer Mode(ATM) is considered as a promising technique to transfer and switch various kinds of media, such as telephone speech, data and motion video. Comparisons among a variety of ATM switching systems which have already been proposed will provide quite useful information for the new ATM switching system design. To facilitate the comparison, we introduce the design requirements and classification criteria for the ATM switch, and propose a performance analysis model for the Banyan network which is the basic switching fabric of most multi-stage ATM switching systems. The model is based on the standard discrete-time Markov chain analysis and can be conveniently used for extensive Banyan network analysis. The computational results are also presented.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.286-293
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• 2002

Photovoltaic systems normally use a maximum power point tracking (MPPT) technique to continuously deliver the highest possible power to the load when variations in the insolation and temperature occur. A simple method of tracking the maximum power points (MPPs) and forcing the boost converter system to operate close to these Points is presented through deriving small-signal model and transfer function of boost converter. This paper aims at modeling boost converter including equivalent series resistance of input reservoir capacitor by state-space-averaging method and PWM switch model. In the future, properly designed controller for compensation will be constructed in real system for maximum photovoltaic power tracking control.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.1
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• pp.70-76
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• 1998

A switch-mode AC/DC converter with high input power factor and sinusoidal input current waveforms is analyzed and modelled for computer simulation. The developed mathematical model for this converter can be used to examine the transient and steady-state performance for selecting the proper ratings of filter, boost inductor and semiconductor devices or the effects of this converter under normal and fault operating conditions on the associated power systems. The proposed model and computer programs are confirmed by comparing with the experimental results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1309-1315
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• 2014

The switch for a maglev vehicle should be designed such that the vehicle safely changes its track without touching the guiderail. In particular, a medium-to-low-speed EMS -type maglev train relies heavily on a U-type electromagnet where it generates levitation force and guidance force simultaneously. Therefore, it is necessary to evaluate the safety of the vehicle whenever it passes the switch, as it lacks active control of the guidance force. Furthermore, when the vehicle passes a segmented switch, which is a group of curves made up of connected lines with a small radius of curvature, it may come into mechanical contact with the guiderail owing to the excessive lateral displacement of the electromagnet. The goal of this study is to analyze the influence of a segmented switch on the safety of major design-related variables for achieving improved running safety. We propose a three-dimensional multibody dynamics model composed of two cars with one body. Using the proposed model, we perform a simulation of the lateral air gap, which is one of the measurements of the running safety of the vehicle when it passes the switch. The analyzed design variables are the length between short span girder, the articulation angle, the length between two centers of a fixed girder at its ends, and the number of girders. On the basis of the effects of the considered design variables, we establish an optimized design of a switch with improved safety.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.6
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• pp.865-876
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• 2018

This study focuses on the operating requirements of multi-resolution modeling(MRM) in training war-game model and proposes solutions for major issues of multi-resolution interoperation between Combat21 model and tank multi-purpose simulator(TMPS). We study the operating requirements of MRM through interviews with defense M&S experts and literature surveys and report the various issues that could occur with low-resolution model Combat21 and high-resolution model TMPS linked, for example, when to switch objects, what information to exchange, what format to switch to, and how to match data resolutions. This study also addresses the purpose and concept of training using multi-resolution interoperation, role of each model included in multi-resolution interoperation, and issue of matching damage assessments when interoperated between models with different resolutions. This study will provide the common goals and directions of MRM research to MRM researchers, defense modeling & simulation organizations and practitioners.

• 전기의세계
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• v.26 no.3
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• pp.63-68
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• 1977

In this paper, the theory of pulse frequency modulated DC/DC power converter to obtain constant output voltage for all input voltage changes is discussed. The switch controller consisting of integrator and comparator determines the ON time of power switch-Thyristor-by the error between the load voltage and a load reference voltage. Resulting voltage and current waveforms have been studied theoretically in detail and verified experimentally for a resistive and inductive load condition. State equations for voltages and currents using binary logic variables are computed by digital computer. Comparison of these withe oscillograms obtained from an experimental model shows very close agreement.