• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1598-1600
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• 1998

When dielectric surface electric field exceed any electric field strength on air, corona discharge is occurred from the dielectric surface. This paper presents corona discharge phenomena on the dielectric in high field were studied under application of ${\pm}DC$ voltage, constitute of the point to plane 20mm gap. The results obtained in experimental are summarized as follow :(1) Corona pulse is appeared periodically after first corona pulse is occurred and the number of corona pulse increases with the instantaneous applied voltage but peak value is not changed greatly.(2)Applied voltage to beccrite and characteristics and peak value of current are almost a straight line. That kind of tendency accorded with characteristics of beccrite resistance.(3)In case of Positive corona, Positive streamers, were progressed greatly to plane electrodes but In case of negative corona, negative streamers smaller than that of Positive corona.

• Journal of the Optical Society of Korea
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• 제15권2호
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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.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.271-277
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• 2004

As one of the concepts of the laser/electric hybrid propulsion system, a feasibility study on possibilities of electrostatic acceleration of a laser ablation plasma induced from a solid target was conducted. Energy distributions of accelerated ions were measured by a Faraday cup. A time-of-flight measurement was also conducted for ion velocity measurement. It was found that an average speed of ions from a pure laser ablation in this case was about 20 km/sec for pulse energy of 40 $\mu$J/pulse with pulse width of 250 psec. On the other hand, through an electrostatic field with a + I ,000 V electrode, the speed could be accelerated up to 40 km/sec. It was shown that the electrode with positive potential was more effective than that with negative potential for positive-ion acceleration in laser induced plasma, or pulsed plasma, in which ions were induced with the Coulomb explosion following electrons. In addition, the ion-acceleration or deceleration strongly depended on conditions of pairs of inner diameter and electrodes gap.

• 한국군사과학기술학회지
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• 제12권5호
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• pp.652-659
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• 2009

To analyze and verify the performance of a pulse radar without the real target data, there is a need to make the simulated signal which is similar to the received signal of the real target. In this paper, a method of the received signal generation for the pulse radar is proposed to solve the above need. The user-made scenarios are used to model the fast and small target and the clutter data based on the ground environment. These data are transformed into the electric signal using the proposed method. The efficiency of the proposed method is proved by comparing the signal of a field test with the simulated signal.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권2호
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• pp.75-81
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• 2006

The purpose of this paper is to recognize the feature points of ECG and human pulse -which signal shows the electric and physical characteristics of heart respectively- using wavelet transform. Wavelet transform is proper method to analyze a signal in time-frequency domain. In the process of wavelet decomposition and reconstruction of ECG and human pulse signal, we removed the noises of signal and recognized the feature points of signal using some of decomposed component of signal. We obtained the result of recognition rate that is estimated about 95.45$\%$ in case of QRS complex, 98.08$\%$ in case of S point and P point and 92.81$\%$ in case of C point. And we computed diagnosis parameters such as RRI, U-time and E-time.

• 한국항해항만학회지
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• 제29권4호
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• pp.341-347
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• 2005

A unique technique to extract the phase in time domain is proposed in order to measure the time parameters such as speed and depth by transmitting sound and electric waves. In the signal analysis processing, the phase of pulse signal can be transformed and digitalized with local data in real time without the effect of direct current bias and Nyquist limits. This method is sensitive to base frequency of pulse signal with high spacial resolution and is effective to compare two signals which have different forms. It is expected that the phase analysis technique will be applied to the measurement of the speed and depth accurately by ultrasonic pulse signal in water.

• 한국가축번식학회지
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• 제26권1호
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• pp.79-85
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• 2002

본 연구에서는 전기자극 후 cycloheximide의 적정농도와 배양시간이 체외성숙된 돼지난자의 활성화에 미치는 영향을 조사하고자 실험을 수행하였다. 42~44시간 동안 체외성숙 된 난자는 0.1%의 hyaluronidase에서 pipetting으로 난구세포를 제거한 후, 1.2 KV/cm의 전압으로 전기자극만 하거나, 전기자극 후 cycloheximide 1, 5 및 10 $\mu\textrm{g}$/$m\ell$의 농도에서 각각 3, 5 및 7시간 동안 배양하는 구로 나누어 활성화를 유도하여 다음과 같은 결과를 얻었다. 1. 난자의 분할율 cycloheximide 10 $\mu\textrm{g}$/$m\ell$ 처리군이 86.8%로 1 $\mu\textrm{g}$/$m\ell$ 처리군의 74.4%보다 유의적(P＜0.05)으로 높았다. 배반포기 발달율은 10 $\mu\textrm{g}$/$m\ell$ 처리구보다 5 $\mu\textrm{g}$/$m\ell$ 처리구에서 유의적(P＜0.05)으로 높았다. 2. 전기자극 후 cycloheximide에서 배양시간의 비교에 있어서 5시간 처리한 돼지난자의 분할율(86.6%)이 3시간 동안 처리한 난자보다 유의적(P＜0.05)으로 높게 나타났다. 상실배의 발달율은 5시간과 7시간 동안 처리구(26.7%와 16.4%)에서 3시간 처리구(14.5%)보다 유의적(P＜0.05)으로 높은 발달율을 나타났다. 3. 전기자극을 단독처리하거나 전기 자극 후 cyclohiximide를 복합처리한 돼지난자를 8일 동안 배양하였다. 전기자극 후 cycioheximide를 복합처리한 난자의 분할율(80.1%) 및 배반포기 발달율(11.6%)은 전기자극 단독처리한 난자의 분할율(77.2%) 및 배반포기 발달율(6.6%)과는 유의적인 차이가 없었다. 4. 체외성숙된 돼지난자를 전기자극 단독 또는 전기자극 후 cycloheximide 복합처리한 후 체외 발달한 배반포기 수정란의 핵 수는 각각 18.67$\pm$5.53개와 20.71$\pm$6.16개로써 유의적인 차이가 없었다. 이상의 결과를 요약하면, 전기자극을 단독처리 하거나 전기 자극 후 cyclohiximide를 복합처리한 돼지난자 발생율은 유의적인 차이가 없었으나, 전기자극 후 cycloheximide를 복합처리 할 경우에는 5 $\mu\textrm{g}$/$m\ell$의 농도로 5시간 동안 배양하는 것이 효과적으로 돼지난자의 activation을 유기할 수 있을 것으로 사료된다.

• 전기학회논문지
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• 제67권4호
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• pp.549-553
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• 2018

The applications of the pulse power technology are expanding and the necessity of a large current switch as a core component of pulsed power is increasing. A trigger gap switch composed of three electrodes was fabricated and the discharge characteristics were studied according to the change of the pressure, the shape of the main electrode, and the gap distance when the trigger pulse was applied. As a main result, the stable operation range was confirmed through the discharge inception voltage according to the gap distance and electric field analysis was performed in the same structure to confirm the electric field value of the discharge inception voltage.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전기물성,응용부문
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• pp.120-122
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• 2003

We have been investigated phase-change with temperature and electric field in chalcogenide $Ge_2Sb_2Te_5$ thin film. $T_c$(crystallization temperature) is confirmed by measuring the resistance and conductivity with the varying temperature on the hotplate. We have measured I-V characteristics with $Ge_2Sb_2Te_5$ chalcogenide thin film. It is compared with I-V characteristics after impress the variable pulse. The pulse has variable height and duration that used voltage and current source.

• 전기의세계
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• 제26권3호
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• pp.76-83
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• 1977

The choice of control method and circuit must be decided after a broad inspection with the characteristics of load and control elements as well as that of electric and mechanical nature. In the present study, Pulse width modulated(PWM) SCR chopper was chosen and for the electric commutation, Jones' forced method was taken bacause of its having enough reverse bias energy. Objectives of experimentation by this system are; 1) the condition of SCR as a gate trigger pulse. 2) the observation of phenomena at the time of forced commutation 3) the experimentation on characteristics of speed control by PWM chopper. Above experimentation shows good characteristics, however, in the limit of narrow gap between the ON and OFF pulses, a complete control was not possible. So, that must be the point to be studied further alone with the harmonics influence.