• Journal of the Optical Society of Korea
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• v.15 no.2
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• pp.182-186
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• 2011

A poling method using multiple negative voltage was introduced to fabricate periodically poled lithium niobate (PPLN) devices with quasi-phase matching (QPM) period of $12.9\;{\mu}m$ by utilizing an real-time visualization system. We also performed variation of the electric field during the poling. Two different conventionally used poling method, negative and positive single pulses, were used and the poling quality compared through microscopic images and far-field diffraction pattern analysis. Etched images on the +z and -z surfaces of PPLN showed that negative multiple pulse poling presented the highest periodicity in domain structures among the three methods. Duty ratio and its standard deviation were measured by analyzing far-field diffraction patterns. The newly introduced method of negative multiple pulse poling had duty ratio of 0.42 which was close to the ideal value of 0.50 and standard deviation of 0.020 that was about 3 times smaller than that of the other conventional methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.2
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• pp.121-131
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• 1992

In this paper, three methods are studied to enhance the performance of SBC ( Sub-Band Coding )schemes for voice signal at the medium bit rate between 12 kbps and If; kbps, and adaptive postfilteritng using human auditory characteristics Is (Bone at the decoder out put. First, GQMF(Generalized Quadrature Mirror Filter ) Is used instead of QME'((Quadrature MirrorFiltcr ) to have better performance. Second, by adaptive bit allocation to each sub-band, speech quality is enhanced and valuable rate ceding If possible. Third, corriparlson study oS thr: coder performance using APCM(Adaptive Pulse Code ModulatioTi) and ADPCM( Adaptive Differentiai Pulse Code Modulatiori) , Indicates that SB AfCM performance better than the other. Adaptive postfiltering at the decoder output enhances the quality of the coded speech. The two proposed postfiltering methods decrease the noise sufficiently at the expense of the low computational load.

• Journal of Welding and Joining
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• v.26 no.1
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• pp.63-68
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• 2008

This paper has aimed to prevent excessive heat input by controlling arc distribution and heat input capacity with pulse GTAW in order to improve weld quality in 0.08mm pressure gauge diaphragm and flange welding parts. A design of experiment was designed using Box-Behnken method to optimize a welding process. The pulse GTAW parameters such as pulse current, base current, pulse duty, frequency and welding speed were set to input variables while hydraulic pressure that represents welding characteristics in diaphragm and flange joint were set to output variables. Based on the test result, a second regression equation was obtained between input and output variables and turned out significant. Besides, an influence of parameters has been confirmed through response surface analysis using the second-order regression equation and optimum welding condition was obtained through a grid-search method. The optimum welding condition was set to pulse current 84.4(A), base current 29.6(A), pulse duty 58.8(%), frequency 10(%), and welding speed 596(mm/min). Then, decent bead shape was acquired with no excessive heat input under the $2.3kgf/cm^2$ of hydrostatic pressure.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.19 no.2
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• pp.91-100
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• 2015

Objectives The aim of this study is to develop a structured clinical protocol related with acquisition of radial pulse wave in the randomized, $2{\times}2$ cross-over design, and cold-heat intervention trial for a pilot and preliminary study. Methods The protocol was contrived based on wide ranging literature searches for cold-heat intervention experiments and radial pulse diagnoses. Results Sample size of 60 subjects was calculated based on an effect size derived from the previous study designed to detect the pre-post cold-heat differences in the radial pulse. Each subjects will be randomly assigned to the cold (first) to heat (last) group (n=30) or heat (first) to cold (last) group (n=30). All subjects will fill out a case report form and questionnaires related with pattern identification, dietary patterns, sleep quality, and physical activity will be surveyed and used as a secondary outcomes. Safety assessment will be reported at the final stage. Conclusions This protocol will provide an additional reference to future studies related with observation of radial pulse during any interventions and also expect to be used as a guideline for acquisition of reliable radial pulse wave data.

• Journal of Industrial Technology
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• v.26 no.B
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• pp.173-181
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• 2006

We analyzed systematically particle growth in the pulsed $SiH_4$ plasmas by a numerical method and investigated the effects of pulse modulations (pulse frequencies, duty ratios) on the particle growth. We considered effects of particle charging on the particle growth by coagulation during plasma-on. During plasma-on ($t_{on}$), the particle size distribution in plasma reactor becomes bimodal (small sized and large sized particles groups). During plasma-off ($t_{off}$), there is a single mode of large sized particles which is widely dispersed in the particle size distribution. During plasma on, the large sized particles grows more quickly by fast coagulation between small and large sized particles than during plasma-off. As the pulse frequency decreases, or as the duty ratio increases, $t_{on}$ increases and the large sized particles grow faster. On the basis of these results, the pulsed plasma process can be a good method to suppress efficiently the generation and growth of particles in $SiH_4$ PCVD process. This systematical analysis can be applied to design a pulsed plasma process for the preparation of high quality thin films.

• The Journal of the Korea Contents Association
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• v.10 no.4
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• pp.257-264
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• 2010

Though existent a transcranial magnetic stimulation makes various treatment and diagnostic sine waveform of fixed stimulation pulse, there is limitation. In this research, because strength, pulse width, pulse pattern required in treatment and diagnostic introduce other Cockroft-Walton circuit and half bridge inverter frequency and voltage variable become new device propose wish to. Have more advantages than existing device. First, do not have high voltage transformer. Second, switching loss can be less, and control output energy precisely. Three, stimulation strengths, pulse width, pulse pattern are various. As a result, sought special quality and an experiment that is improved applying inverter and cockroft - Walton circuit is half bridge inverter that do not use transformer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.211-212
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• 2007

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.319-321
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• 2004

We report on progress in developing high-power excimer lasers as well as UV-optics for creating low-temperature poly silicon (LTPS). A new high-power excimer laser offers 315 Watts with high pulse to pulse energy stability. Larger substrates can now be processed in better quality with either the SLS process or the new optics for line beam excimer laser annealing.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.5
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• pp.152-158
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• 1996

A novel resonant pulse control technique which generates high-quality sinusoidal output voltage from a resonant dc link inverter is presented for UPS applicatons. The proposed control technique limits resonant voltae overshoot without any passive or active clamp circuit, resulting in resonant pulses iwth uniform amplitude and high efficiency. The output voltage is controlled by the third order contorller iwth an inner loop of th efilter inductor current and the feedforward controller. Analysis and design of the proposed control technique are illustrated and verified on a 5kVA experimental unit.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.8
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• pp.27-33
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• 1993

This paper presents a mobile measurement technique of the ghost-flutter caused in mobile television reception. The ghost-flutter is caused by timing variation of the television horizontal synchronizing pulse due to frequency selective fading in a multipath propagation environment. The ghost-flutter can be detected by measuring the dynamic timing variation of horizontal synchronizing pulse. Especially, in this paper, a technique for measuring horizontal synchronizing timing fluctuations which cause the ghost-flutter is developed, using a Rubidium oscillator as a time standard with high stability.