• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.1
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• pp.167-171
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• 2018

We have developed ideal products that need low power by utilizing astable multivibraters since we are in need of technology that can be adaptable to any environments anytime because tons of thousands of electric products and IT products need to be operated by low power DC motors. Since motors generally use much electricity in an initial stage of operation, we have testified and proved the technology that can be furnished with any kinds of motors including those of AC and DC by loading them with on-off systems with electric pulse with operating methodology that has realized low-electrical operation when normally operated.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.3
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• pp.211-218
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• 2005

Switched Reluctance Motor(SRM) offers the advantages of simple and robust motor construction, high speed and high efficiency over a wide operating range of torque and speed, excellent controllability. However SRM has the disadvantages of high current harmonics, and low power factor because the required output of speed and torque is produced by the discontinuous and loss of power system, and brings about the incorrect operation of electronic system. This paper deals with an energy efficient converter fed SRM system with the reduced harmonics and improved power factor. The validity of the proposed scheme is verified via experiments. We are implemented the proposed control system using 80C196KC micro-controller.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.2B
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• pp.160-169
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• 2002

While radar operator recognizes and tracks threat targets through the scope, it is essential to overcome the jamming signal that disturbs the normal operation of the radar. Therefore, to train operator and test the EW capability of the radar, this paper proposed the jamming signal simulation algorithm and design results to generate the deception jamming(range, velocity, angle deception and multiple false targets) and noise jamming signals(spot, barrage, swept spot and cover pulse noise). And also, the radar jamming signal simulator composed of the 6 constituents is developed on basis of the proposed algorithm and digital circuit design technique and confirmed the validity of the developed simulator by means of the test results to generate the various jamming signal.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.305-306
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• 2008

본 논문에서는 PRAM 에서 기록매질로 이용될 수 있는 최적의 물질을 찾고자 $Ge_2Sb_2Te_5$ 박막에 Al을 첨가하여 비정질-결정질 천이시의 원자구조와 상변화 특성간의 관계를 연구하였다. 이 실험에 사용된 $Al_x(Ge_2Sb_2Te_5)_{1-x}$ 조성은 5N의 금속 파우더를 용융-냉각법으로 벌크를 제작하였고 열증착 방법으로 Si (100) 및 유리 (corning glass, 7059) 기판위에 200nm 두께로 박막을 증착하였다. 비정질 박막의 상변화에 따른 반사도 차이를 평가하기 위해서 658 nm의 LD가 장착된 나노펄스 스캐너를 이용하여 power; 1~17mW, pulse duration; 10~460 ns의 범위에서 각 조성의 비정질-결정질 상변화속도를 측정, 비교 분석하였다. 또한 각각의 박막을 $100^{\circ}C$ 에서 $400^{\circ}C$ 까지 $50^{\circ}C$ 간격으로 $N_2$ 분위기에서 1시간동안 열처리 한 후 XRD와 UV-Vis-NIR spectrophotometer를 사용하여 각 상의 구조분석 및 광학적 특성을 분석하였다. 또한 4-point probe로 면저항을 측정하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.419-420
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• 2008

In this work, we report several experimental data capable of evaluating the phase transition characteristics of (InTe)x(GeTe)y (x = 0.1, 0.3, y =1) pseudo-binary thin films. (InTe)x(GeTe)y phase change thin films have been prepared by thermal evaporator. The crystallization characteristics of amorphous (InTe)x(GeTe)y thin films were investigated by using nano-pulse scanner with 658 nm laser diode (power : 1~17 mW, pulse duration : 10~460 ns) and XRD measurement. It was found that the crystalline speed of In-Ge-Te thin films are faster than $Ge_2Sb_2Te_5$[1] and also the crystalline temperature is higher. Changes in the optical transmittance of as-deposited and annealed films were measured using a UV-VIS-IR spectrophotometer and four-point probe was used to measure the sheeresistance of InGeTe films annealed at different temperature.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.1
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• pp.1-10
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• 2010

Design and performance evaluation of $H_2O_2$ monopropellant thrusters to be used at reaction control of space launch vehicles were presented in this paper. Design thrust level was determined as 100, 250 Newton which is nominal thrust level for commercial space launch vehicles. Qualification thruster models including solenoid valves were developed after the reactor design were evaluated at engineering thruster models. Each thruster was evaluated by measurement of characteristic velocity, thrust, specific impulse, and pulse response times at sea level test condition.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.516-521
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• 2005

The application of UWB not only complies with the requirements of remote sensors system(ECG), it also contributes to the effectiveness of the implementations through its unique qualities such as ultra low transmission power - an important factor when dealing with biomedical equipment. In this paper, the aim is to replace the wired ECG sensors with a wireless link and design wireless UWB communication system. The various pulse shapes are presented that satisfies the FCC spectral mask and FCC part 15 rule. It is shown that UWB can be a high rate transmission over short ranges using Rake receiver, with the capability for reliably transmitting 100Mbps over distance at about 10 meters.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.308-312
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• 2002

In this paper, EPLD(Erasable Programmable Logic Device) based induction motor drives with a SRP-PWM(Separatley Randomized Pulse Position PWM) is proposed. In the proposed RPWM (Random PWM), each of three phase pulses is located randomly in each switching interval. Based on the space vector modulation technique, the duty ratio of the pulses is calculated. To verify the validity of the proposed RPWM, the experimental study was tried. Along with the randomization of PWM pulses, the space vector modulation is also executed in the TMS320C31 DSP(Digital Signal Processor). The experimental results show that the voltage and switching noise harmonics are spread to a wide band area. Also, the performance of the proposed SRP-PWM and the conventional SVM-PWM are nearly the same from the viewpoing of the v/f constant control.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.4
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• pp.423-434
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• 1989

In this paper, a PRS transmission system using TMRCP as the unit pulse is proposed, which solves the problems occur when the PRS method will be applied to the digital transmultiplexer for each channel. And a design technique which uses this PRS method for the FFT polyphase filter transmultiplexer concept is given. TMRCP-PRS signal require a bandwidth about 2.5KHz(including some guard-band) for a 4-KHz bandlimited voice channel. Therefore, in he 24 channel transmission line, it gives the same advantages as he ordinary PRS system and sloves the inter-channel interference problems. And its good speed-tolerance reduces the time-errors by the environments and the power loss, so it makes the system to be stable. The total system, however, attaces the filters for PCM-PRS, PRS-PCM conversion before and after the transmultiplexer respectively.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1797-1799
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• 2002

$SF_6$ 가스로 절연되는 GIS (Gas Insulated Switchgear)는 매우 우수한 신뢰성을 확보하고 있지만 사고 발생 시 파급효과가 매우 크므로 상시 감시할 수 있는 진단기술이 요구된다. 본 논문에서는 GIS 내부에서 발생하는 신호를 검출하기 위해서 전기적인 방법과 비전기적인 측정 법을 통해 전자파. 초음파, 전류펄스를 측정하고 비교하였다. GIS 내부알루미늄도체에 침 결함을 고정시켜 전원전압 인가 시 발생되는 부분방전신호를 UHF, AE, CT센서로 검출하였다. 측정 결과 UHF센서와 CT센서로 검출되어진 신호는 매우 유사하게 측정되었고 초음파와 전자파를 검출한 결과 진행속도 차이로 발생되는 시간지연현상이 발생되었다. GIS내 부분방전발생 시 발생되는 전자파 스펙트럼 분석결과도 650MHz에서부터 935MHz까지의 주파수대역이 측정되었다. 이후에는 현장에서 운전중인 GIS내부에서 발생되는 결함들을 실제와 가깝게 모델링하여 발생되는 부분방전신호를 스펙트럼 분석하여 대역에 맞는 UHF센서 개발에 노력하고자 한다. 또한 결함의 종류와 형태에 따라 다르게 발생되는 부분방전신호를 검출하여 측정하고 이를 진단하는 연구가 계속 진행되어야 할 것으로 사료된다.