• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.129-133
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• 2005

This paper discusses DC/DC converter modeling using average model of switch and critical characterist. Average model of switch approach is expended to the modeling of boundary conduction mode DC/DC converters that operate at the boundary between Continuous Conduction Mode(CCM) and Discontinuous Conduction Mode(DCM). Frequency responses predicted by the average model of switch are verified by simulation and experiment.

• Journal of Power Electronics
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• v.17 no.2
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• pp.323-333
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• 2017

This paper proposes a model-based optimal control algorithm for the clamp switch of a zero-voltage switching (ZVS) bidirectional DC-DC converter. The bidirectional DC-DC converter (BDC) can accomplish the ZVS operation using the clamp switch. The minimum current for the ZVS operation is maintained, and the inductor current is separated from the input and output voltages by the clamp switch in this topology. The clamp switch can decrease the inductor current ripple, switching loss, and conduction loss of the system. Therefore, the optimal control of the clamp switch is significant to improve the efficiency of the system. This paper proposes a model-based optimal control algorithm using phase shift in a micro-controller unit. The proposed control algorithm is demonstrated by the results of PSIM simulations and an experiment conducted in a 1-kW ZVS BDC system.

• 연구논문집
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• s.29
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• pp.57-67
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• 1999

This paper presents the status quo of the development of a piecewise bendable switch system for the urban transit MagLev. MagLev system as well as railroad requires switch systems to reach its destination. Requirements of the switch system for commercial lines are high speed operation satisfying about 2-3 minute headway and system reliability, etc. Parallel moving type switch system was installed on the test track of urban transit MagLev in KIMM. In this system, switch operation from one position to another can be done in about 90 seconds. Therefore, we concluded that this system can not satisfy the headway for the commercial lines. We decided to develop a high speed piecewise bendable switch system in which switching can be done in 20 seconds. Designed switch system is very complicated in view of operating mechanism. It consists of 11 segmented girder beams driven by hydraulic cylinders. To gain the idea of a piecewise bendable switch system, we manufactured and tested a 1/5 scale switch model. We are going to construct a full scale piecewise bendable switch system next year.

• Journal of Information Technology Services
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• v.10 no.3
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• pp.149-166
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• 2011

While the importance of adopting cloud computing service has been emerged, comparatively little research has been conducted on examining factors of an individual user's intention to switch toward cloud computing service. Hereafter, this study presents and empirically tests users' intention to switch to cloud computing. Our model posits that the characteristics of cloud computing such as collaboration support, accessability, trust to cloud service affect perceived value, which in turn, influences intention to switch. An experimental study using student subjects provided empirical validation for our proposed model. Survey data from 106 respondents was used to test the model using partial least square analysis. According to our results, the characteristics of cloud computing were found to have significant impact on users' intention to switch that partially mediated by perceived value. Based on our research findings, we hope that this research will stimulate researchers' interest in the emerging area of cloud computing adoption.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.8
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• pp.1926-1940
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• 1998

This paper is the part II of research results on the performance evaluation of fully interconnected ATM switch, and includes the performance evaluation results for bursty traffic and nonuniform distribution. The switch model is a fyully interconnected switch type proposed by ETRI and is the proper architecutre for a small-sized switch element. The proposed switch consists of two steps of buffering scheme in the switch fabric in order to effectively absorb the effect of bursty nature of ATM traffic. The switch uses bit addressing method for addressing shcmeme and thus it is easy to implement multicasting function without adding additional functional block. In order to incorporate the bursty nature of traffic in ATM networks, we use IBP(Interrupted Bernoulli Process) model as an input traffic model as well as random traffic model which has been used as a traditional traffic model. In order to design the various scenarios for simulation, we considered both uniform and nonuniform output distribution, and also implemented multicast function. In this paper, we presented the simulation results in diverse environments and evaluated the performance of the switch.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1025-1028
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• 1992

In this paper the flyback converter analysis is presented using the model of the PWM switch, which is easier to use than the general method of state-space averaged model. A procedure to design the flyback convertor and the feedback circuit is illustrated. From these results, a stable flyback convertor regulation system is possible by using the PWM switch model.

• International Commerce and Information Review
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• v.6 no.1
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• pp.157-189
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• 2004

Recently, Digital Switch has risen as one of the important issues on which academic and industrial world focus in order to bring organizational transformation to a company that wants to adapt itself to the rapidly changing business environment. However, the discussion in the Digital Switch has been so much concentrated in the study of each static system, model of their performance and the development of monitoring each of them, that only few theoretical research has been carried out on the dynamic process of how each system in the organization experienced the change in terms of the level of digital transformation that can occur in the whole organization facing the change of digital environment. Therefore this thesis aims to develop a new model & strategy of switching to global digital by OEM companies in Jeonlabuk-do that enables us to check out and predict the Digital Switch progress. This model is the first Digital Switch process evaluation intended for empirical study, especially by integrating the many indices that have not been examined empirically by the existing studies. We expect that the results from this research will help corporate e-business strategy planners to devise and analyze the Digital Switch strategies effectively by recognizing the companies' current situation in comparison with their previous and other firms' level, respectively.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.4
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• pp.205-211
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• 2003

In this paper we propose a disturbance design method to test a system's stability. It is shown that the time maximum disturbance is represented in bang-bang and state feedback form. To maximize the time severity index, the value of disturbance is determined by the associated switch curve. The original switch curve is vulnerable to model uncertainties and takes much calculation time. We propose an improved method to approximate the original switch curve. This reduces the computational time and implements sufficiently to test the stable system. Simulation results show how the approximate switch curve can be used to stress a system by driving it to oscillation along the maximum limit cycle.

• Journal of Power Electronics
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• v.18 no.1
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• pp.1-10
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• 2018

Recently, the nine-switch inverter has been proposed as a dual output inverter. To date, studies on the control strategies for NSIs have been mostly combined with their application. However, in this paper, a mathematical model and control strategy for nine-switch inverters has been proposed in view of the topology. A switching function model and equivalent circuit model of a nine-switch inverter have been built in ${\alpha}{\beta}$ coordinates. Then, a novel current observer with an improved integrator is proposed based on the switching function model, and a direct power control strategy is proposed. No current sensors are used in the proposed strategy, and only two voltage sensors are employed. The performance of the proposed control method is verified by simulation and experimental results.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.175-185
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• 2015

Generally, in the train area, switch tracks have required high reliability because this system is directly associated with derailment. Especially, switch tracks of Maglev vehicles must be moved in terms of the whole geometric characteristics, in which the bogies are encased in the switch track. For this reason, switch track was constructed with steel lighter than concrete girders. But, the steel switch track was weak because of structural vibration as well as structural deformation. Therefore, it is important to predict the levitation stability when a vehicle passes over flexible switch track. The aims of this paper are to develop a coupled dynamic model to describe the relationship between a Maglev vehicle and switch track and to predict the levitation stability. In order to develop the coupled dynamic model, a three dimensional vehicle model was developed based on multibody dynamics; a switch model was made using the modal superposition method. And, the developed model was verified using comparison measured data.