• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.145-148
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• 1986

To perform the marking on metal with high speed and non-contact using the laser beam of high energy, laser marking system is designed and fabricated applying the galvanometer scanner capable of high speed-precise beam positioning controlled by microprocessor. Laser is a Q-switched Nd:YAG producing multi-mode, wavelength, 1060nm. Optical system is composed of beam expander, scanning mirror and flat field lens. Consequently, the laser marking is satisfactorily achieved regardless of kinds of metal.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.87-90
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• 2002

This paper describes design technique of switched-capacitor 1V delta-sigma modulator. To solve the incomplete switching operation at low voltage, bootstrapping technique is used. For PMOS input pair of 1V operational amplifier, simple common mode level down technique is used. Designed 2nd order single loop modulator has an oversampling ratio of 64 and obtains a peak SNR of 71dB, a dynamic range of 73 dB with the power consumption of 350uW at 1V power supply.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2145-2147
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• 1998

This paper presents a Class-D type switched mode audio power amplifier employing ZVT(Zero-Voltage-Transition) soft switching technique. In order to obtain a wide bandwidth and lower distortion for an audio amplifier a high switching frequency is essential. The ZVT switching scheme enables a high frequency switching without sacrificing the efficiency much as in a hard switching. A prototype amplifier is built to demonstrate the feasibility of this technique for the audio power amplifier.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.218-219
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• 2001

본 실험에서는 RF 소자들과 650 nm InGaAIP FP LD를 사용하고 이득스위칭에 의하여 선폭이 35psec 되는 극초단 광펄스를 생성하였다. 또한 이렇게 생성된 극초단 광펄스를 이용하여 언덕형 굴절률 분포를 가지는 다중모드 광섬유의 대역폭을 빠른 푸리에 변환(Fast Fourier Transform)으로 계산하였다 따라서 본 실험에서 이용된 언덕형 굴절률 분포를 갖는 다중모드 광섬유의 대역폭은 670 MHz.km로 측정되었다.

• International Journal of Internet, Broadcasting and Communication
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• v.5 no.1
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• pp.6-8
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• 2013

In this paper, we present an intelligent digital controller circuit which can be applied to automatic voltage regulation. The proposed solid state transformer with Pspice simulation model shows that our approach is very efficient and produces the desirable output. It is comparable to an ordinary magnetic coupled autotransformer.

• 전기의세계
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• v.43 no.12
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• pp.67-72
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• 1994

ITU-T(구 CCITT)의 X.25에 기초한 패킷교환 방식은 회선교환에 비하여 대역폭을 효과적으로 사용할 수 있는 장점을 갖고 있으나 흐름제어와 오류제어 처리에 따른 지연으로 속도가 64Kbps로 제한된다는 것이 단점이다. 특히 90년대에 들어서부터는 문자 정보만 전송하던 80년대와는 달리 데이타량이 큰 그래픽 및 화상데이타의 전송수요가 늘어나고 있으며 LAN 및 클라이언트 서버 환경의 도입으로 대표되는 기업의 컴퓨팅 환경의 변화가 급속히 이루어지고 있어서 기업의 통신환경이 기존의 패킷교환 방식만을 갖고는 도저히 감당할 수 없게 되었다. 이에 따라 고속 패킷교환기술들이 80년대 후반부터 등장하기 시작하였으며, 공중 데이타망 기술로 대표적인 것은 프레임릴레이(FR), SMDA(Switched Multimegabit Data Service), ATM(Asynchronous Transfer Mode) 등이다.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.45-48
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• 2002

Switched Reluctance Generator attracts much attention because of high efficiency, simple controllability with traction drive. But the theories that have been adopted as SRG control methods are complicated up to the present. This paper proposes reference current limitation strategy for stable generation and switching angle control in motoring mode. The proposed method is verified by simulation and experiments.

• Journal of Power Electronics
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• v.6 no.2
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• pp.121-130
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• 2006

This paper presents the performance and efficiency of a drive system incorporating a switched-reluctance motor (SRM) with input power factor correction (PFC). The proposed system consists of a PFC, bi-directional converter, an inverter, and a SRM operating as based voltage source drives (VSD). First, theoretical analysis is made for each identified mode of operation in the drive system. This is followed by comparing the performance of the SRM drive system with and without a PFC circuit. The losses are also calculated for both systems and overall efficiency. Experimental results are presented to prove the theoretical analysis.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.3
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• pp.95-105
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• 2019

A method that applies space-time adaptive signal processing (STAP) algorithm based on an array antenna consisting of multiple antenna elements has been known to be effective to remove wide-band jamming signals in GPS receivers. However, the occurrence of phase distortion in navigation signals has been a problem when navigation signals, from which jamming signals are removed using STAP, are supplied to global positioning system (GPS) receivers. This paper verified the navigation performance degradation as a result of phase distortion. To mitigate this phenomenon, this paper proposes a mode switching scheme, in which a bypass mode is adopted to make the best use of the tracking performance of receivers without performing signal processing when jamming signals are not present or weak, and a STAP mode is employed when jamming signals exceed the threshold value. In this paper, the mode switching scheme is proposed for two environments: when receivers are stationary, and when receivers are moving. This paper confirmed that the performance of position error improved because phase distortion could be excluded due to STAP if the bypass mode was adopted under a condition where the jamming signal power level was below the threshold value in an environment where receivers were stationary. However, this paper also observed that the navigation failed due to the instability of tracking performance of receivers due to phase distortion that occurred at the switching time, although the number of switching could be reduced dramatically by proposing a dual threshold scheme of on- and off-thresholds that switched a mode due to the array antenna characteristics of varying gains according to the jamming signal incident direction in an environment where receivers were moving. The analysis results verified that running the STAP algorithm at all times is more efficient than the mode switching, in terms of maintaining stable navigation and ensuring position error performance, to remove jamming signals in an environment where receivers were moving.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.5
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• pp.35-41
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• 2008

This paper presents the design method of current-mode signal processing for high speed and low power digital audio signal processing. The digital audio processor requires a digital signal processing such as fast Fourier transform (FFT), which has a problem of large power consumption according to the settled point number and high speed operation. Therefore, a current-mode signal processing with a switched Current (SI) circuit was employed to the digital audio signal processing because a limited battery life should be considered for a low power operation. However, current memory that construct a SI circuit has a problem called clock-feedthrough. In this paper, we examine the connection of dummy MOS that is the common solution of clock-feedthrough and are willing to calculate the relation of width between dummy MOS for a proposal of the design methodology for improvement of current memory. As a result of simulation, in case of that the width of memory MOS is 20um, ratio of input current and bias current is 0.3, the relation of width between switch MOS and dummy MOS is $W_{M4}=1.95W_{M3}+1.2$ for the width of switch MOS is 2~5um, it is $W_{M4}=0.92W_{M3}+6.3$ for the width of switch MOS is 5~10um. Then the defined relation of MOS transistors can be a useful design guidance for a high speed low power digital audio processor.