• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1600-1602
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• 2001

A pulsed power supply of 2.4MJ capacitor bank has been developed to make investigation into electric gun technology. It is made up of eight paralleled 300kJ modules, and can supply various shape of high current pulse by changing charging voltage, inductance, capacitance, and firing time of each module. The 300kJ module has been designed and fabricated for the maximum operating voltage of 22kV, peak current of 150kA, and pulse duration of 1msec. The experiments of the modules were done, and the equivalent circuit of the module was determined. The characteristics of the module were analyzed more deeply through the circuit simulation. The experiments of the paralleled modules with inductance of 20 $\mu$H and load resistance of 100 m$\Omega$ were performed, where the modules were discharged simultaneously and/or sequentially. The results of the experiments were analyzed. The 2.4MJ capacitor bank is currently used as the pulsed power supply for the ETCG (Electro Thermal Chemical Gun) research.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1238-1243
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• 2009

As Social Overhead Capital(SOC) has been expanded, the highway road construction has been accelerated and city road system has been more complicated. So, long road tunnels have been increased and traffic flow rate also has been raised. Accordingly, the exhausting gas of vehicle cars seriously deteriorates the tunnel inside air quality and driving view. In order to improve tunnel inside air quality, it is needed to introduce a compulsory ventilation system as well as natural ventilation mechanism. The former, that is, a special compulsory ventilation facility is very useful and helpful to prevent a tunnel of being contaminated by traffic in most case. In the case of obtaining clearer and longer driving view, the ventilation systems have to be considered in order to remove floating contaminants or exhaust gas from engines. In this paper, discharge electrode design technology will be discussed.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2317-2318
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• 2008

This report is about wireless energy transform system. It means something to charge without a line of contact. Existing charging has been many defect, including badness of the line, limitation of the space and the time and so on But this is one of the way that can complement it. So our goal is making the wireless charger that is effective and easy to use.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2251-2252
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• 2008

Recently, voltage sag from sudden increasing loads is also one of the major problems inside the utility network. In order to compensate the voltage sag problem, power compensation device systems could be a good solution method. In case of voltage sag, an energy source is needed to overcome the energy loss caused by the voltage sag. Superconducting Magnetic Energy Storage (SMES) is a very promising source of this energy due to its fast response of charging and discharging time. Before constructing the power electronic delivering system for the SMES, it is necessary to simulate the system to understand its behavior. Nowadays, a lot of devices have been developed to compensate voltage sag such as Dynamic Voltage Restorer (DVR), Distribution Static Compensator (D-STATCOM) and Uninterruptible Power Supply (UPS). In this paper, focus is given only on DVR system which will be simulated by using PSCAD/EMTDC software.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.7-13
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• 2013

Power system in satellite shall produce stable outputs for successful mission accomplishment. However, unstability in overall electrical system is caused in a case where a load having a power profile with high-powered and micro-cycled pulse shape is connected to a satellite power system. In order to resolve this anomaly, "power system stabilization method using a battery" featured with simplicity can be applied, but there is a constraint to operate a battery in its normal operational conditions. In this paper, an effective interface structure for "power system stabilization method using a battery" is suggested and a battery protection algorithm for preventing over-charging and over-discharging is discussed.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.990-991
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• 2015

To drive a magnetron injection gun, thsi paper decribes a design, fabrication and analysis results of proposed compact capacitor charging power supply (CCPS) formed resonant full-bridge inverter for electron gun power supply (EGPS). EGPS needs the -40 kV output voltage and 280 kW output power for few seconds continuously and have to be designed for the rise and fall time to be less than 1 ms with the ripple stability of output voltage of lower than 1%. In order to meet the requirements, we used eight resonant full-bridge modules operated in parallel. Each resonant full-bridge module can supply the current of 0.9 A and the voltage of 40 kV, and is operated by N-phase shift switching pattern. In this paper, we present the design, simulation and test results of interleaved CCPS.

• Journal of Communications and Networks
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• v.7 no.2
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• pp.192-206
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• 2005

Integration of mobile networks and Internet has started with 2.5 generation of mobile cellular networks. Internet traffic is today dominant traffic type worldwide. The hanger for higher data rates needed for data traffic and new IP based services is essential in the development of future wireless networks. In such situation, even 3G with up to 2 Mbit/s has not provided data rates that are used by Internet users with fixed broadband dial-up or through wired local area networks. The solution to provide higher bit rates in wireless access network has been found in wireless LAN although initially it has been developed to extend wired LAN into wireless domain. In this paper, we propose and describe a solution created for interoperability between mobile cellular network and WLAN. The integration between two networks, cellular and WLAN, is performed on the authentication, authorization, and accounting, i.e., AAA side. For that purpose we developed WLAN access controller and WLAN AAA gateway, which provide gateway-type access control as well as charging and billing functionalities for the WLAN service. In the development process of these elements, we have considered current development stadium of all needed network entities and protocols. The provided solution provides cost-effective and easy-to-deploy PLMN-WLAN Internetworking scenario.

• Journal of Power Electronics
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• v.13 no.4
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• pp.558-568
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• 2013

In this paper, a new decoupling technique for a flyback inverter using an active power decoupling circuit with auxiliary winding and a novel switching pattern is proposed. The conventional passive power decoupling method is applied to control Maximum Power Point Tracking (MPPT) efficiently by attenuating double frequency power pulsation on the photovoltaic (PV) side. In this case, decoupling capacitor for a flyback inverter is essentially required large electrolytic capacitor of milli-farads. However using the electrolytic capacitor have problems of bulky size and short life-span. Because this electrolytic capacitor is strongly concerned with the life-span of an AC module system, an active power decoupling circuit to minimize input capacitance is needed. In the proposed topology, auxiliary winding defined as a Ripple port will partially cover difference between a PV power and an AC Power. Since input capacitor and auxiliary capacitor is reduced by Ripple port, it can be replaced by a film capacitor. To perform the operation of charging/discharging decoupling capacitor $C_x$, a novel switching sequence is also proposed. The proposed topology is verified by design analysis, simulation and experimental results.

• Tribology and Lubricants
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• v.33 no.6
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• pp.296-302
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• 2017

Ball milling of elemental powders in advance and using an induction heating system for intermetallic coatings are known to enhance the reactivity of combustion synthesis. In this work, the effects of simultaneously applying these two incentive methods on the properties of intermetallic coatings are studied. Ni-Al powder compacts ball-milled with three different ball-to-powder weight ratio mixtures are synthesized and coated on mild steel by combustion synthesis in an induction heating system. Consequently, similar to an electrical heating system, the positive effects of ball milling on the combustion synthesis are confirmed in the induction heating system. The enhancement in synthetic reactivity achieved by applying the two incentive methods at the same time is greater than that by applying each incentive method separately. In particular, the enhancement is remarkable at low reaction temperature. However, there are limitations to improving the reactivity by simultaneously applying the two incentive methods to the combustion synthesis, unlike the reaction temperature. The microstructure and hardness of the coating layer are both influenced by the ball-charging ratio employed in the ball-milling process.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.5
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• pp.189-193
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• 2003

Initial irreversible capacity (IIC) can be defined by means of the initial intercalation Ah efficiency (IIE) and the initial irreversible specific capacity at the surface (IICs) with the linear-fit range of the intercalation so as to precisely express the irreversibility of an electrode-electrolyte system. Their relationship was IIC = Qc - Q$_{D}$ = (IIE$^{-1}$ - 1) Q$_{D}$ + IICs in the linear-fit range of IIE. Here, Qc and Qd signify charge and discharge capacity, respectively, based on a complete lithium ion battery cell. Charge indicates lithium insertion to carbon anode. Two terms of IIE and IICs depended on the types of active materials and compositions of the electrode and electrolyte but did not change with charging state. In an ideal electrode-electrolyte system, IIE and IICs would be 100%, 0 mAh/g for the electrode and mAh for the cell, respectively. These properties can be easily obtained by the Gradual Increasing of State of Charge (GISOC).OC).