• Electronics and Telecommunications Trends
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• v.29 no.5
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• pp.145-155
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• 2014

최근 급격히 증가하고 있는 모바일 데이터 트래픽으로 인하여 이를 효과적으로 수용할 수 있는 수동형 광 가입자망(PON: Passive Optical Network) 기술에 대한 요구사항도 높아져가고 있다. 특히, 서비스 제공 시간을 줄이고 망 신뢰성을 향상시키며 망 운용관리 비용을 줄이기 위하여 PON 인프라인 광 분배망(ODN: Optical Distribution Network) 링크에 대한 실시간 장애 검출 기술과 물리적 광 커넥션의 자동인식 및 통합관리 기술에 활발한 연구 및 표준화가 진행 중이다. 본고에서는 PON 링크의 실시간 장애 검출 기술 및 광 분배망 자동인식/통합관리 기술동향에 대하여 소개하고 연계된 국제 표준화 진행사항에 대해 알아본다. 마지막으로 ETRI에서 연구 개발 중인 스마트 RN(Remote Node) 기술에 대해 기술한다. 스마트 RN 기술은 장거리(60Km 이상), 고분기(128분기 이상) 추세로 진화되고 있는 PON망에 적용하여 자동화된 광계층의 장애 검출 및 ODN 인프라 자동인식/통합관리 기능을 제공한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.951-954
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• 2006

RFID시스템은 태그와 리더, 백엔드DB로 구성되는 무선인식시스템으로 용도와 기능, 크기에 따라 다양하지만 가장 널리 사용될 것으로 예상되는 것은 저가 수동형 태그로 향후 바코드시스템을 대체할 것으로 기대된다. 이러한 RFID시스템은 적법한 리더와 태그에게 정보를 전달해서 도청자로부터 통신을 방해받지 않아야 하고, 원하지 않는 태그 정보의 노출로 인한 개인 프라이버시 침해를 방지할 수 있어야 한다. 본 논문에서는 불특정다수가 이용하는 많은 양의 아이템을 취급하는 공공도서관에서 RFID시스템을 도입함에 따라 예상되는 개인 프라이버시 침해를 방지하기 위해 보안 요구사항을 만족하면서 시스템 사용 환경에 맞는 프라이버시 보호 방식을 제안한다.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.663-665
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• 2004

Ethernet-based passive optical network(EPON) technology is being considered as a promising solution for next-generation broadband access network. It must have the property of high efficiency, low cost, and support quality of service(QoS). A major feature for this new architecture is the use of a shared transmission media between all connected optical network unit(ONU). Hence, medium access control(MAC) arbitration mechanisms are essential for the successful implementation of EPON. In this paper we propose a simple dynamic bandwidth allocation(DBA) algorithm that improves the performance of network and supports IP-based multimedia applications with the bursty data traffic. In addition, we introduce analytic models of proposed algorithms and prove the system based on our algorithm to be asymptotically stable. Simulation results show the new DBA algorithm provides high bandwidth efficiency and low queueing delay of ONU in EPON.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.6
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• pp.10-19
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• 2010

아바타 영화 이후 영화 시장뿐만 아니라 방송 시장에서도 3D로의 전환이 급속하게 이루어지고 있다. 전 세계적으로 3D 관련 표준화 작업이 활발하게 이루어 있고, 관련 장비 및 솔루션 또한 3D 디스플레이를 선두로 카메라 및 3D 포스트 프로덕션 장비를 포함하여 다양한 장비들이 실제 상용 서비스가 가능한 수준으로 개발이 되고 있다. 시청자 관점에서 보면 셔터링 방식이 주를 이루고 있지만 머지않아 무안경 방식의 3D 솔루션이 선보일 것으로 예상된다. 이러한 움직임에 이어 또 한편으로는 기존 수동형 방송이 아닌 사용자가 직접 참여하고 네트워크 및 소셜 서비스가 가능한 형태의 스마프 TV가 관심을 불러 일으키고 있다. 본 논문에서는 향후 3D가 지향해야 할 하나의 방향이라고 볼 수 있는 스마트 3D에 대해서 개념을 정의하고, 3D가 스마트해지기 위해 필요한 환경 및 요소 기술에 대해서 기술하고자 한다.

• Journal of Sensor Science and Technology
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• v.23 no.4
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• pp.238-244
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• 2014

In this paper, we introduce a new passive transponder that operates without external power in a visible light identification system. The transponder consists of a solar cell, a photodiode, a microprocessor, and a visible LED. When a reader sends light to the transponder, the solar cell generates current from the reader light and supplies power to the other elements in the transponder. At the same time, the photodiode detects the pulse in the reader light and initiates a microprocessor to generate and send a responding light to the reader. In experiments, we realized a passive transponder using a solar cell that operated at a distance of 1m without external power.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.169-176
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• 1996

In order to suppress the structural vibration more effectively, Multiple Tuned Mass Damper(MTMD) which is composed of a number of Tuned Mass Damper(TMD) can be used. Especially, the passive MTMD has several advantages over active TMD like easy installment and maintenance, cost and performance for power failure situation(severe damage of power lines from earthquake), etc.. For this purpose the mass and damping ratio of MTMD and the distributed frequency range which shows the range of MTMD's distribution are used as main design parameters. When the passive MTMD is constituted with multiple cantilevers, the facility in its real production and its need for only a smaller space can be named as its several advantages. In this study, the satisfactory results were obtained from the composition of MTMD utilizing dynamic characters of cantilevers, and the verification was done by the comparison of the analysis from MTMD with the computer simulation.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.9
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• pp.22-29
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• 1997

This paper describes a three dimensional profile measurement method for sheet metal products which have flexible and porous sculptured surfaces. Shadow masks are used as measuring objects for practical implementation or this study. The shadow masks are located inside the fluorescent glasses of monitors for televisions or computers and used to prevent electron guns from interfering between pixels. Three dimen- sional surface profiles are measured by adopting a software autofocusing technique to capture focused images. The experimental results show that the method is very effecive and suitable for sheet meal prod- ucts with flexible and porous surfaces.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2319-2323
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• 2010

The existing contact-type bearings using rolling or sliding require continuous maintenance due to abrasion caused by friction and are not suitable for high-speed rotation and slimming. A magnetic bearing without contact can overcome such problems but the performance depends on the allocation of magnets and the structure of bearings. This paper proposes a method designing parameters of a passive magnetic bearing to improve levitation force. The proposed method employs Halbach array as the allocation of magnets, uses particle swam optimization to determine the structure of bearings. The numerical experiment shows that the levitation force is improved by the proposed method compared with the existing one using finite element analysis.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.4 s.19
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• pp.91-99
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• 2004

Laser materials for eyesafe wavelength generation and Q-switching crystals for short pulse operation were studied and compared with each other. Er,Yb:phosphate glass as a laser material and $Co^{2+}:MgA1_2O_4$ as a saturable absorber were found to be an effective pair for a compact, light-weight passively Q-switched eyesafe laser operation. Simplified rate equation was used to estimate pulse parameters of the diode-pumped passively Q-switched laser.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.138-143
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• 2010

This paper presents the analysis, the fabrication and the test results of a micro passive gas pressure regulator to keep the outlet pressure costant even for a widely-varying inlet pressure. This device is to regulate the outlet pressure according to the applied reference pressure based on the pressure balancing mechanism of the structure including a membrane and a valve. This regulator consists of four layers; a bulk-micromachined silicon substrate, a sandblasted glass substrate, a PDMS valve seat layer and a glass valve layer. The device size is $10\times13\times1.7 mm3$. The device was fabricated by micromachining. The characteristic of the device was analyzed and tested. The characteristic of the fabricated pressure regulator is similar to that obtained from the analysis. The pressure regulator of this paper is feasible for portable systems and miniature drug delivery systems.