• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.7
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• pp.316-321
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• 2002

In this Paper, the channel characteristics of the medium voltage(22.9kV) power line to analysis the broadband power line communication in the frequency range up to 30MHz was measured. With the sideband electrical coupler in the operating frequency range from DC to 30MHz, we measured characteristic impedance, noise and attenuation of the medium voltage power line, and then characteristic impedance was measured at the state of unloaded medium voltage power line by Scattering parameter method of Vector Network Analyzer. As a measurement result, Channel impedance shows 100~380$\Omega$ at the less than 15MHz and 70~230$\Omega$ at the more than 15 MHz. Noise characteristics of power line shows -75dBm at 20MHz and Narrowband interference noise was from 3 MHz to 7MHz.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.9
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• pp.1475-1482
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• 2001

Nowadays reduction of gear noise in power transmission is very important, because the noise regulation is severe and demand of customer on noise is increased. To reduce gear noise, it is necessary to understand the noise characteristics of helical gear. In this work, we designed test rig for the study of gear noise and installed in semi-anechoic chamber. By using this rig, sound pressure level is measured under varying rotational speed and torque. The frequency characteristics of helical gear noise on the effect of lead errors and torque are discussed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.640-643
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• 2001

최근 인터넷 사용의 급격한 확산으로 인해, 이제까지 전화망을 위주로 발전되어 왔던 통신망의 구조에 많은 변화가 일어나고 있다. 최근 우리나라에서도 지식 정보사회의 기반이 되는 초고속 정보통신망으로의 접속으로 발전되고 있으며, 이용 환경을 무선 방식으로 제공할 수 있는 30 GHz 주변 대역에서 BWLL 용 주파수를 할당하고 있다. 또한 실내용 초고속 무선 LAN, 차량 충돌 방지 시스템 등을 비롯한 Intelligent Transportation System, 그리고 국방 기술 둥 여러 분야에서 밀리미터파 대역 신호를 사용한 기술 개발이 요구되고 있다. 따라서, 본 논문에서는 이러한 밀리미터파를 생성하기 위한 여러가지 방법들을 설명하고, Sideband injection locking 방법을 제안하여 수치적인 컴퓨터 시뮬레이션을 통하여 그 가능성을 분석하였다.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.5
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• pp.575-582
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• 2007

In this paper, a 100 Watt high power amplifier has been implemented and performed evaluation, which is operating at UHF band ($470\;{\sim}\;806\;MHz$) for Digital TV repeater. To achieve increase of bandwidth and high power capability, 3-way power combiner and divider of Wilkinson type was adopted. In order to measure the fabricated 100 Watt power amplifier, the estimation technique function which makes equivalent mask was used. As a result of the measurement, the existence of pilot signal is confirmed and the signal transmitted at the rated output power 100 Watt is brought out the flat feature through 6 MHz bandwidth. and it resulted that its value was less than -47 dB at the edge of radiation channel and less than -110 dB at more than 6 MHz position from channel edge.

• Korean Journal of Optics and Photonics
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• v.14 no.2
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• pp.161-165
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• 2003

Optical 60 ㎓ millimeter-wave (MMW) signal generation is demonstrated using the sideband injection-locking method in the master/slave configuration, where two slave lasers are locked to two among several side-bands produced by the direct rf-modulation of a master laser. These two locked slave laser outputs beat against each other in the photo-detector and produce stable and very pure 60 ㎓ signals.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.298-302
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• 2006

Models for the phase noise and jitter of the ring oscillator with the power supply noise are suggested and verified by simulations. The power supply noise is converted into the phase-noise by the narrow band phase modulation. The phase-noise appears as sideband frequencies apart from the center frequency of the ring oscillator as much as the frequency of the power supply noise. A jitter model describing the linear relation of jitter with the amplitude of the power supply noise is suggested and verified by simulation.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.245-246
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• 2015

본 논문에서는 삼중 델타 전원과 새로운 커먼-모드 필터 결선을 통해 스위칭에 의한 고조파를 저감하는 방법을 제안한다. PWM에 의해 생성되는 측대파 고조파(Sideband harmonics) 위상을 분석함으로써, 인터리빙 운전 시 삼중 델타 전원 연결과 제안된 커먼모드 필터가 측대파 고조파 전류를 크게 저감할 수 있음을 보인다. 3개의 고정자 권선을 가지는 영구자석 전동기를 이용하여 제안된 필터의 유효성을 검증하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.802-808
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• 2000

This paper characterizes the electromechanical parameters due to the fault of rotor bars in a squirrel cage induction motor. Simulation is performed to investigate how broken rotor bars have effect on them by solving the time-stepping finite element equation coupled with magnetic field equation, circuit equation and mechanical equation of motion. It shows that the asymmetry of magnetic flux due to the broken rotor bar introduces the beating phenomenon in time domain and the sideband frequencies in frequency spectra, respectively, to the stator current, torque, speed, magnetic force and vibration of a rotor. However, vibration of a rotor would be the most effective monitoring parameters to detect the faults of rotor bars.

• Journal of the Optical Society of Korea
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• v.18 no.3
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• pp.288-291
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• 2014

This paper presents a new method for measuring the half-wave voltage $V_{\pi}$ of an electro-optic phase modulator based on a phase-modulated photonic link with interferometric demodulation. By using this method, the $V_{\pi}$ can be obtained with the RF voltage amplitude input required to achieve 1-dB gain compression of link and the differential delay of a Mach-Zehnder interferometer. We measure the $V_{\pi}$ of a commercial phase modulator by using the presented method and the carrier/the first sideband intensity ratio method. Furthermore, we compare the two measurements with the typical value provided by the manufacturer. The experiment shows that this novel measurement method is feasible, straightforward, and accurate.

• ETRI Journal
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• v.41 no.1
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• pp.32-41
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• 2019

We propose a speckle reduction technique in electronic holographic display systems, where digital micro-mirror array devices are used as spatial light modulators. By adopting a programmable filtration in a general 4-f optic configuration, it is shown that the signal spectrum components in the frequency domain of a viewing-window-based holographic display system can be selectively filtered. Compared to the widely utilized single-sideband filtration techniques in electronic holographic display systems, our proposed programmable filtration can be utilized to effectively reduce the speckles in the reconstruction of point-cloud-based computer-generated holograms. Experimental results are presented to verify our proposed concept.