• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.281-283
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• 1993

A new method of EEG spindle waveform detection i s presented. The method combines the signal conditioning in the time-domin and the analysis of local spectrum in the frequency-domain. Fast computation methods, utilizing some effective approximations, are also suggested for the desist and implementation of the filter as well as for the computation of the local spectrum. The presented approach is especially useful for the real-time implementation of the waveform detection system under a general purpose microcomputer environment. The overall detection system is implemented and tested on-line with the total 24 hour data of selected four subjects. The result show the average agreement of 86.7% with the visually inspected result.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.361-363
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• 2003

The purpose of this research was to discuss the system that operated Ultra sonic transducer of Pelzo electric ceramics type. The structure of controller was made up of digital signal part drive and feedback circuit, and half bridge inverter. Digital signal part was designed to gain the stable oscillation frequency by making consideration of pointed resonance bandwidth. We tried to control inverter by forward feedback condition because BLT based on the flexibility of elements such as temperature and load condition. In addition, transducer was operated as inverter in order to enhance its power efficiency. In this experiment, output voltage waveform and current waveform have been observed by using BLT.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.185-187
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• 1995

A boost converter proposed in this paper operates with high power factor due to input current of sinusoidal waveform. If there were no input LPF, the current is got to be discontinuos form in proportion to AC input voltage magnitude under the constant duty factor switching. Thereupon, the harmonics of input current waveform is reduced and the LPF is made with few elaboration and the control circuit is simple. The switching devices in proposed circuit are operated with soft switching by the partial resonant method. The patial resonant circuit makes use of a reactor using step-up and a capacitor of loss-less snubber. The result is that switching loss is very low and efficiency of system is high.

• The Journal of the Acoustical Society of Korea
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• v.16 no.4
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• pp.106-109
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• 1997

In the area of the speech synthesis techniques, the waveform coding methods maintain the intelligibility and naturalness of synthetic speech. In order to apply the waveform coding techniques to synthesis by rule, however, we must be able to alter the pitches for prosody control of synthetic speech. In this paper, we propose a new pitch alteration technique in time-frequency hybrid domain, that compensates phase distortion of the cepstral pitch alteration method with time scaling method in the time domain. This method can remove some phase spectrum distortion which is occurred in conjunction point between the waveforms in continued frames. Also, we can obtain little magnitude spectrum distortion below 1.18% for pitch alteration of 200%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4740-4744
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• 2012

The purpose of this paper was to make a LED light control module using Zigbee. The module was made so that brightness of the LED light changes according to the ambient brightness. A 8-bit microcontroller was used to implement the module to enable LED dimming and wireless light intensity measurement. Using the proposed method, power consumption can be improved by up to 48% on average, with 3.4-0.4W changes in power. The measured ambient light intensity values are converted from analog to digital and outputted as a PWM waveform. According to the output waveform and changes in the current outputted from the LED driver, the brightness of the LED light is controlled. Also, Zigbee with close-range wireless communication capabilities was used to enable wireless transmission of light intensity measurements.

• Journal of Welding and Joining
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• v.23 no.1
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• pp.69-76
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• 2005

Recently, application of arc welding to galvanized carbon steel sheet is on the increasing Ould in the fields of automobile and construction industries. In arc welding process, zinc is evaporated in weld pool, even under the appropriate welding condition and produce blowhole and/or pit. Zinc gas cause instability of arc and increase spatter and fume. This research is purposed to minimize the heat-input and the formation of porosities in the welded joint of the galvanized carbon steel sheet using variable polarity AC wave pulse MIG welding system. An appropriate welding condition which showed low spatter and good bead appearance was acquired by applying the AC pulse MIG welding machine to DC duplicated MIG welding with the solid wire. When oxygen gas was added to shield gas of MIG welding for galvanized steel sheet, arc length was increased and arc stability was improved. In the AC duplicated welding, the loss of galvanized layer was decreased as the amount of heat-input was decreased when the EN ratio was increased under the condition that average welding current was evenly set.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.4
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• pp.308-314
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• 2015

This paper has proposed a new boost rectifier. Adequate input current was obtained by keeping the duty ratio constant without complicated conventional control methods and the improvement of the waveform was increased. With a decrease of distortion up to 12.9[%], the scope of restriction on harmonics was set to 13.0[%]($3^{td}$ harmonics), 1.1[%]($5^{td}$ harmonics) and 0.6[%]($7^{td}$ harmonics), respectively. Because complicated methods of control are avoided, the circuit configuration is simple and practical. In particular, the said effect turned out to be highly efficient in the low boosting ratio range(boosting ratio$({\alpha})=1.25$). The feasibility of these facts has been proven both theoretically and experimentally.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4159-4164
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• 2012

This paper presents a chaotic circuit with voltage controllability for secure communication applications. The proposed circuit which has two control voltages consists of the nonlinear function block(NFB) with three MOS transistors, one source follower and non-overlapping two-phase clock generator for sample and hold. By SPICE simulation, chaotic dynamics such as time waveform, frequency analysis and bifurcations were analyzed. SPICE results showed that proposed circuit can make various chaotic signals by control voltage.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.156-158
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• 2007

Laser wave length can have evaporation effect by absorption because outer skin or tissue of focus is consisted of water almost though absorption of water occurs more than 90% almost in formation thickness of very thin floor Can operate outer skin, steam by floor and correct incision of formation is available. Suture surgical operation is avaliable to vein or lymph system and surgical operation region can dry and see as eye and radish bleeding surgical operation is avaliable Specially, stability of tube both end output about pulse by weight very, this research can cause various curative effect because can reduce bulk and control easily current wave style of medical laser using electric power conversion device of high frequency way. If introduce ZVS (Zero Voltage Switching) or ZVZCS (Zero Voltage and Zero Current Switching), is more profitable because can reduce switching damage Because electric power department of proposed medical laser can do stable soft-switching in wide subordinate extent introducing ZVZCS technique by the first help and control department composes microcontroller, output current waveform user have free form make. Result that experiment because design and manufacture, brought result that improve of 20% than existing equipment, and will be bought to get into superior result if supplement as systematic late.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.52-54
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• 2007

Laser wave length can have evaporation effect by absorption because outer skin or tissue of focus is consisted of water almost though absorption of water occurs more than 90% almost in formation thickness of very thin floor. Can operate outer skin, steam by floor and correct incision of formation is available. Suture surgical operation is available to vein or lymph system and surgical operation region can dry and see as eye and radish bleeding surgical operation is available. Specially, stability of tube both end output about pulse by weight very, this research can cause various curative effect because can reduce bulk and control easily current wave style of medical laser using electric power conversion device of high frequency way. If introduce ZVS (Zero Voltage Switching) or ZVZCS (Zero Voltage and Zero Current Switching), is more profitable because can reduce switching damage. Because electric power department of proposed medical laser can do stable soft-switching in wide subordinate extent introducing ZVZCS technique by the first help and control department composes microcontroller, output current waveform user have free form make. Result that experiment because design and manufacture, brought result that improve of 20% than existing equipment, and will be bought to get into superior result if supplement as systematic late.