• 대한전자공학회논문지
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• 제16권1호
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• pp.1-8
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• 1979

비동기 디지탈 변조 시스템은 일반적으로 아날로그(analog) 신호를 시간축상에 샘플링(sampling)하지 않고 진폭축상에서 양자화하기 때문에 그 출력펄스는 보통 랜덤(random)하여 재래의 동기식 시분할 다중방식은 적용하지 못한다. 아날로그 신호를 터지탈 코오드화하게 되면 전송회로의 비직선성이나 중계기의 잡음 누적 등의 문제점이 어느 정도 해소되므로 여기에 Pierce의 다중통신 방식(1)을 적용하기로 하고 이를 실현시키는데 알맞는 디지탈 변조방식에 대해서 고찰하였다.

• 대한전자공학회논문지
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• 제25권3호
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• pp.335-342
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• 1988

In this paper, we proposed a new algorithm for EMG low frequency analysis. Through the power spectrum analysis of Gaussian's, Gamma's and Erlang's PDF(probability density function) based on the proposed algorithm, the proper PDF of IPI (inter pulse interval) representing the firing rate of muscle was suggested. In order to verify the proposed algorithm EMG signals of masseter and biceps muscle were detected by surface electrode and its power spectrum analysis was performed. The experimental results are compared with the computer simulaiton. As a result, the masseter muscle's IPI was fitted by Gamma PDF, having a 10Hz fundamental frequency including n(1+\ulcornerfp high harmnic frequency on 10% MVC(maximum voluntary contaraction). And the biceps muscle's IPI was fitted by Gaussian PDF, also it have a 14Hz fundamental frequency.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1999년도 학술대회논문집-국제 전기방전 및 플라즈마 심포지엄 Proceedings of 1999 KIIEE Annual Conference-International Symposium of Electrical Discharge and Plasma
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• pp.228-233
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• 1999

In this paper we develop an electronic starter circuit that is suitable for Neon sign operation of switch-start fluorescent lamps. The developed starter enable single pulse ignition of fluorescent lamp at the peak point of preheating current, irrespective of the position of the Tum-On signal. This is possible due to the sequential operation of two transistors different in their operation characteristics and a diode operation characteristic. The switching endurance test using this starter has been carried for more than 3000 hours for a single switch-start on a severe blinking condition of preheating of 0.1s and of successive lighting interval of 0.1s.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.343-346
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• 2002

In recent, complex SVPWM (Space Vector PWM) algorithm can be easily implemented by high performance microprocessor and DSP. Various SVPWM techniques are widely studied due to the advantages of low harmonic distortion and high use ratio of D.C. link voltage. Most of various studies for improving of VS-PWM inverter performance are concentrated about switching pattern and zero pulse pattern split algorithms. However, dc link voltage that is determined at rated load and speed conditions is not proper in the low speed and under rated load. In this paper, analysis of current ripple with digitally implemented SVPWM inverter is introduced according to link voltage. The optimal link voltage in the designed inverter system and load condition is provided in order to suppress output voltage error and current ripple. As remaining the effective voltage vector interval per sampling period sufficiently, additional voltage error and current ripple are suppressed. The proposed algorithm is verified through digital simulation and experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.316-319
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• 1998

RPWM(Random Pulse Width Modulation) is a switching technique to spread the voltage and current harmonics on the wide frequency area. Using randomly changed switching frequency of the inverter, the power spectrum of the electromagnetic acoustic noise cab be spread to the wide-band area. The wide-band noise is much more comfortable and less annoying than the narrow-band one. So RPWM have been attracting an interest as an excellent method for the reduction of acoustic noise on the inverter drive system. In this paper a new RPPWM (Random Position PWM) is proposed and implemented. Each of three pulses is located randomly in each switching interval. Along with the randomization of PWM pulses, the space vector modulation is executed in the C167 microcontroller also. The experimental results show that the voltage and current harmonics were spread to wide band area and that the audible switching noise was reduced by proposed RPPWM method.

• Journal of Power Electronics
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• 제11권1호
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• pp.28-36
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• 2011

In this paper, a three phase cycloconverter type high frequency AC link inverter is discussed. The configuration consists of a high frequency full-bridge inverter and a high frequency transformer followed by a three phase cycloconverter whose switch is composed of anti-series connected MOSFETs with a common source. A simple digital control strategy based on space vector modulation (SVM) and repetitive control for the cycloconverter is proposed although its input voltage is a high frequency AC pulse. The operation principle of the proposed control strategy is analyzed and the equivalent working modes during one interval are also presented. The effectiveness of the proposed control strategy is verified through Matlab/Simulink simulations and experiments on a 1.45kW prototype.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.82-89
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• 2002

In this paper, a new two-phase space vector RPWM(Random PWM) is proposed. In the proposed RPWM, each of two-phase PWM pulses is located randomly in each switching interval. Based on the space vector modulation technique, the duty ratio of the pulses is calculated. Along with the randomization of the PWM pulses, we can obtain the effects of spread spectra of inverter output voltage, d.c link current and audible switching acoustic noise as in the case of randomly changed switching frequency. To verify the validity of the proposed two-phase RPWM scheme, the experiment based on the C167 micro-controller was executed. The performance of the proposed scheme was compared with traditional PWM schemes experimentally.

• 대한안전경영과학회지
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• 제15권1호
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• pp.141-150
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• 2013

In this paper, the learnability of haptic icons was tested as a way of conveying turn-by-turn directions to users involved in navigation interactions with commercial smartphones. To do this, six most distinctive haptic icons were identified from those having different duration of each pulse, interval between pulses, and rhythm. Associations between the selected haptic icons and 3 pairs of navigation directions were analyzed using data gathered from 30 subjects by 7 point Likert scale. The haptic icons were then assigned to proper directions based on the results from that stereotype analysis. The results showed that the commercial smartphone with one linear motor at a fixed location is not capable of making hapticons to have clear directional stereotypes. The hapticons with poor stereotypes has no advantage in learnability compared to those of random assignment.

• 한국시뮬레이션학회논문지
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• 제9권3호
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• pp.1-11
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• 2000

This paper proposes the practical echo-signal synthesis models - UTAHID (Underwater TArget by Highlight Distribution) & M-UTAHID(Modified UTAHID) - of underwater target for active sonar engineering At high frequencies all the echo components that are the specular reflected waves and various elastic scattering wave scan be regarded the summation of individual echo from some equivalent scattering centers, so the underwater target is characterized by highlights distributed in spatial target structure. Proposed models are compared with characteristics of random distributed model & equivalent interval highlight model, and analyzed target strength, echo-elongation effect, target time spread loss and so on. Thus these can be efficiently used in various real systems related to underwater target echo-signal synthesis on active sonar and acoustic countermeasure.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.119-122
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• 2007

Dual auxiliary pulses are adopted in an AC PDP with an auxiliary electrode. The secondary auxiliary pulse of dual auxiliary pulses efficiently utilizes priming particles and contributes to improved luminous efficacy. A shorter time interval between the two auxiliary pulses resulted in better efficacy. The maximum luminous efficacy was approximately 12 lm/W according to measurement of the discharge in a Ne+20%Xe gas-mixture and green cells.