• Journal of the Korean institute of surface engineering
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• v.30 no.4
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• pp.262-271
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• 1997

Nickel-matal hydride(Ni-MH) batteries are receiving attention as non-pollunting. high performance rehargeable energy stoage system. The performance of Ni-Mh is significantly influenced by the hydrogen storage alloy materiels used as an anode material. Recently, having discharge capacities higher than the $AB_5$-type hydrogen storage alloys, the Zr-based $AB_2$-Type hydrogen storage alloys has remaining problems regarding cycle life and self-dischareg. These problems need to be solved by improvements in the alloy design and/or surface treatment. This work investiggates the effects the effects of surface property by fluorination on $Zr_{0.7}Ti_{0.3}V_{0.4}Mn_{0.4}Ni{1.2}$ composittion $AB_2$-Type hydrogen storage alloys. EPMA, SEM and AES techniques were used for surface analysis, and the crystal structure was characterized by constant current cycling test and potential sweep methods. Fluorination was found to be effective when La-was incorporated into the alloy, and has unique morphology, higher reactivity, and at the same time formed a protective film. Through, fluorination, the cycle life of an electrode was found to increase significantly, charge/discharge characteristics of the electrode the potential difference between the charge/discharge plateau, i.e polarization(overpotential)were improved.

• Journal of the Korean Society of Safety
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• v.16 no.2
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• pp.57-62
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• 2001

In order to analyze the mechanism of semiconductor device damages by ESD, this paper adopts a new charged-device model(CDM), field-induced charged nudel(FCDM), simulator that is suitable for rapid routine testing of semiconductor devices and provides a fast and inexpensive test that faithfully represents ESD hazards in plants. The high voltage applied to the device under test is raised by the fie]d of non-contacting electrodes in the FCDM simulator. which avoids premature device stressing and permits a faster test cycle. Discharge current md time are measured and calculated The FCDM simulator places the device at a huh voltage without transferring charge to it, by using a non-contacting electrode. The only charge transfer in the FCMD simulator happens during the discharge. This paper examine the field charging mechanism, measure device thresholds, and analyze failure modes. The FCDM simulator provides a Int and inexpensive test that faithfully represents factory ESD hazards. The damaged devices obtained in the simulator are analyzed and evaluated by SEM Also the results in this paper can be used for to prevent semiconductor devices from ESD hazards.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.642-646
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• 1989

We have developed analysis program of discharge chracteristics of KrF laser system with charge transfer type, that studied about deposited energy, nonlinear discharge, and electron number density in the laser tube. With this program, voltagr, current, and deposited energy was calculated 27 KV,32.6 KA,200 MW at total pressure 2 atm and charging voltage 33 KV, respectively. At this condition, circuit parameters are L1=150nH, R1=$0.3{\Omega}$, L2=15nH, R2= $0.3{\Omega}$. In addition, nonlinear discharge resistance and electron number density was calculated ${\infty}{\sim}0.17{\Omega}.1{\times}10^{16}cm^{-3}$, respectively.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.416-418
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• 2008

Cost effective and high efficiency energy recovery circuit (ERC) using an address voltage source is proposed. Different from prior ERC, the proposed circuit uses a voltage source to charge a panel and a current source to discharge the panel. As a result, it can be achieved zero voltage switching (ZVS) of switches in H-bridge inverter and zero current switching (ZCS) of switches of the ERC. Moreover, the proposed ERC can obtain high efficiency, high performance and the decrease of the cost and the size.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.376-379
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• 2005

High efficiency and low cost sustain driver for plasma display panel (PDP) with current fed is proposed. Main concept of the proposed circuit is using the current source to charge and discharge panel. As a result, all power switches can achieve the zero voltage switching (ZVS) and every auxiliary switch can also do the zero current switching (ZCS). Moreover, since the inductor current can compensate the discharge current, the current stress of all power switches can be reduced considerably. Furthermore, it has features as a simpler structure, less mass, less cost, and lower electromagnetic interference than prior circuit.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.344-348
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• 2009

One-dimensional modeling was carried-out to predict the capacity loss of a lithium-ion polymer battery during cycling. The model not only accounted for electrochemical kinetics and ionic mass transfer in a battery cell, but also considered the parasitic reaction inducing the capacity loss. In order to validate the modeling, modeling results were compared with the measurement data of the cycling behaviors of the lithium-ion polymer batteries having nominal capacity of 5Ah from LG Chem. The cycling was performed under the protocol of the constant current discharge and the constant current and constant voltage charge. The discharge rate of 1C was used. The range of state of charge was between 1 and 0.2. The voltage was kept constant at 4.2 V until the charge current tapered to 50 mA. The retention capacity of the battery was measured with 1C and 5C discharge rates before the beginning of cycling and after every 100 cycles of cycling. The modeling results were in good agreement with the measurement data.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.05a
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• pp.79-84
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• 1993

This paper describes the development of lithium rechargeable cell. $LiCoO_2$ is recently recognized as a suitable cathode active material of a high voltage, high energy lithium rechargeable batteries because $Li^+$ ion can be electrochemically deintercalated/intercalated from/to $Li_xCoO_2$. The transition metal oxide of $LiCoO_2$ was investigated for using as a cathode active material of 4V class Li rechargeable cell. $LiCoO_2$ cathode was prepared by using a active material of 85 wt%, graphite powder of 12 wt% as a conductor and poly-vinylidene fluoride of 3 wt% as a binder. The electrochemical and charge/discharge properties of $LiCoO_2$ were investigated by cyclic voltammetry and galvanostatic charge/discharge. The open circuit voltage of prepared $LiCoO_2$ electrode exhibited approximately. potential range between 3.32V and 3.42V. During the galvanostatic charge/discharge, $LiCoO_2/Li$ cell showed stable cycling behavior at scan rate of 1mV/sec and potential range between 3.6V and 4.2V. Also its coulombic efficiency as function of cycling was 81%~102%. In this study the $LiCoO_2/Li$ cell showed the available discharge capacity of 90.1 mAh/g at current density of $1mA/cm^2$ and cell discharge voltage range between 3.6V~4.2V.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.851-854
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• 2004

This paper studies Optical Fiber(OF) - LED illuminated display board system for energy saving. The OF-LED illuminated display board system has PV modules, batteries, and charge & discharge system, and dynamic full color display controller. Both maximum power point tracker (MPPT) and constant current & constant current controls (CCVC) are used In govern the charging system. It can be improve the charging efficiency of battery. The objective of this thesis paper is to build advertisement lighting system with OF-LED in to charge a 12-volts lead acid battery by using a field wired PV array. We saved the maintenance cost and developed of advertisement effectiveness. To verify the proposed OF-LED illuminated display board system for energy saving, the detail simulation and experiment results indicate that operating characteristics are verified by experiment with a laboratory prototype in this paper.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.181.1-181.1
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• 2014

Supercapacitor is attracting growing attention for a promising energy conversion and storage device because of its desirable electrochemical properties such as rapid charge-discharge rate, high power density and long cycle life. Three-dimensional (3D) metal nanostructure has been widely studied since it can provide efficient charge transport along the 3D network in many device applications. In this work, we fabricated well-ordered 3D nickel (Ni) nanostructures using 3D-arrayed polystyrene nano-opal substrates. We also fabricated half-cell supercapacitors by electrodepositing $RuO_2$ onto these nanostructured Ni current collectors and investigated their morphological and electrochemical properties.

• Bulletin of the Korean Chemical Society
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• v.6 no.4
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• pp.218-221
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• 1985

Transient charging and discharging currents as well as space charge limited currents have been measured in biaxially stretched poly(vinylidene fluoride) film under various poling fields and temperatures. At low temperatures and short poling times, the I-V characteristics showed shallow trap behavior. When the current values extrapolated to the infinite time, the I-V characteristics indicate that the distribution of the trap energy levels is uniform or very broad. The abnormal suppression of current at higher poling voltages and the high discharge rate observed also in the same voltage range are attributed to the morphological changes due to dipole reorientation.