• Information and Communications Magazine
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• v.31 no.8
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• pp.74-83
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• 2014

수동형 광가입자망 (PON: Passive Optical Network) 기술은 가입자의 단말과 국사의 장비를 광섬유로 직접 연결하여 기존의 전화선 및 동축케이블을 이용한 xDSL 및 HFC등에 비해 전송속도가 빠르고 관리가 수월한 인터넷 서비스 제공이 가능한 기술이다. 본고에서는 ITU-T와 IEEE에서 진행중인 차세대 수동형 광가입자망 기술의 국제 표준화 동향에 대하여 알아보고, 관련 기술개발 현황 및 새롭게 부각되는 스마트 광 분배망 기술과 SDN (Software Defined Network) 기반 광가입자망 운용관리 등의 연구분야에 대하여 알아본다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.52-54
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• 2005

모든 사물에 고유 식별 정보(Unique Product Identifier)가 부착되어 사물의 개별 관리 및 컴퓨팅 환경을 구성하는 RFID(전자식별) 기술이 다양한 응용 및 구현 기술을 위해 활발하게 연구되고 있다. 하지만 수동형 태그 기반 RFID 시스템은 태그 자체의 자원 제약성 때문에 인가되지 않은 사용자에 의한 악의적인 태그 점보 노출이 용이하고, 그 결과 개인의 프라이버시 및 정보의 기밀성이 위협받게 된다. 비록 이를 예방하기 위해 다양한 보호 기법이 제안 되고 있지만 수동형 태그에 적용하기 힘들거나(예: Hash 기반 메카니즘) 보안에 취약하다. 따라서 본 논문에서는 태그 코드 암호화와 리더 인증 관리를 통해서 수동형 태그에 적합하고 프라이버시 보호 및 기밀성을 제공할 수 있는 메카니즘을 제안하고자 한다.

• The Journal of the Acoustical Society of Korea
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• v.35 no.5
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• pp.375-382
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• 2016

This paper presents the results for the performance improvement of underwater communication in a passive time reversal mirror (PTRM) using ray-based blind deconvolution (RBD). In conventional PTRM, the signal to be recovered is found from matched-filtering the received probe signal. However, the communication performance is degraded because the time-varying impulse response for each data frame is not reflected in the received probe signal. In this study, the time-variant transfer function is estimated from each received data frame using RBD, and the estimated time-variant transfer function is then used to recover the data signal using PTRM. The results from the experimental data show that the suggested method improves the communication performance when comparing with the conventional PTRM.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.29 no.5
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• pp.19-23
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• 2000

어떠한 흡임재도 사용하지 않아 청정환경을 유지하고, 흡음형 소음기로는 잘 제어되지 않는 63Hz에서 250Hz까지 저주파대역의 소음을 감쇠하기 위하여 개발된 대체기술을 소개하고자 한다

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.82-88
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• 2009

Power capacitor is generally installed to compensate for the low power factor of inductive load But it has been used as passive filter to reduce harmonics generated by the power conversion device. Passive filter is composed by the series connection of reactor and capacitor. Because passive filter has play an important role on the absorber of harmonics, it takes voltage and current stress, follows partially burned on flamed and degradation, finally it has not guaranteed normal life. In this paper, we analyzed the effect that passive filter installed at the source side of PWM inverter is received by harmonics absorption.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.648-650
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• 2015

In this research, we investigate an influence of a reader antenna location in Passive UHF RFID system based Object localization. When the localization system uses stationary RFID reader system, the performances of the system are significantly varied depending on the deployed antenna conditions due to its external environment such as reflection by the ground and obstacles. In this research we deeply study the RF conditions and differentiation with various antenna location. According to the empirical results, the localization system shows the best performance, where the reader antenna locates 1.5m from the target area of interest.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1141-1146
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• 2011

In this paper, an adaptive RFID tag antenna in 900MHz for using in inadequate electromagnetic environment is designed and implemented. The dimension of the proposed passive tag is $102mm{\times}102mm{\times}9mm$, the operating frequency band is 908~914MHz and the detection range is 5.1m. This paper describes the development of the thermal, water and impact resisting tag. The implemented tag can be used for the inadequate environment such as in-built tag on the ground for the car management service.

• Journal of the Institute of Convergence Signal Processing
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• v.18 no.1
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• pp.21-24
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• 2017

Passive millimeter wave (MMW) imaging penetrates clothing to detect concealed objects. The distances extraction to the concealed objects is critical for the security and defense. In this paper, we address a passive stereo 3 mm MMW imaging system to extract the longitudinal distance to the concealed object. The concealed object area is segmented and extracted by the k-means clustering algorithm with splitting initialization. The distance to the concealed object is estimated by the corresponding centers of the segmented objects. In the experimental two pairs (each pair for horizontal and vertical polarization) of stereo MMW images are obtained to estimate distances to concealed objects.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.1
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• pp.26-32
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• 2017

This paper presents a low power and high resolution incremental delta-sigma ADC that utilizes a passive integrator instead of an opamp-based active integrator. Opamp is a power-hungry block that involves tight design tradeoffs. To avoid the use of active integrator, the s-domain characteristic of an active integrator is first analyzed. Based on the analysis, an active integrator with low gain design is proposed as an alternative design method. To save power even more aggressively, a passive integrator with no static current is proposed. A 1st order single-bit incremental delta-sigma ADC using the proposed passive integrator is implemented in a 65nm CMOS process. Transistor-level simulation shows that the ADC consumes only 0.6uW under 1.2V supply while achieving SNDR of 71dB with 22kHz bandwidth. The estimated total power consumption including digital filter is 6.25uW, and resulting power efficiency is on a par with state-of-the-art A/D converters.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.2
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• pp.213-220
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• 2016

This research aims to develop core technologies for passive carrier (no power in carrier itself) transfer system. The technologies are passive levitation, propulsion, and guidance, which can be great benefits for semiconductor and display manufacturing industries. Passive maglev carrier is necessary to precise position control for quiet and stable transfer operation. However, the structural characteristics of carrier and the installation errors of gap sensors cause the pitch motion. Hence, the controller design in consideration of pitch motion is required. This study deals with the reduction control of carrier pitch motion. PDA controller and PDA controller with pitch control are proposed to compare the pitch angle analysis. The pitch angle and the levitation precision are measured by experiment. Finally, the optimized design of pitch controller is presented and the effects are discussed.