• 한국구조물진단유지관리공학회 논문집
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• 제20권4호
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• pp.51-58
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• 2016

콘크리트 구조물은 내구성과 경제성이 확보된 건설재료이지만, 매립된 철근의 부식은 내구적인 문제뿐 아니라 구조물의 안전성에 큰 영향을 준다. 본 연구는 유리섬유와 강재를 에폭시로 일체화 시킨 FRP Hybrid Bar를 적용한 콘크리트에 대해 염해 침투 저항성과 부식수준에 따른 부착성능을 평가하였다. 이를 위해 일반 강재를 적용한 OPC(Ordinary Portland Cement)시편과 GGBFS를 30% 혼입한 시편에 대하여 부식을 0~10% 촉진하여 부착력을 평가하였다. 또한 FRP Hybrid Bar는 에폭시 코팅으로 인해 보통 상태에서는 부식 진전이 매우 작으므로 notch를 인위적으로 가하여 OPC 콘크리트에 매립시켰으며, 이후 부식실험을 수행하였다. 실험 결과, 부식된 철근의 부착력이 21% 수준으로 감소해도 FRP Hybrid Bar에 발생된 notch는 부착력에 큰 영향이 없는 것으로 평가되었다. 또한 GGBFS 콘크리트를 사용한 부재의 경우, 통과 전류가 감소하여 일반철근을 사용해도 70%이상의 부착력을 유지하고 있었다.

• 비파괴검사학회지
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• 제36권4호
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• pp.288-294
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• 2016

Flexible ECT (eddy current array) probe를 사용하여 판재 및 용접부에 존재하는 notch 결함을 MS-5800E와 OmniScan MX 장비로 검출능력을 비교하고, 주파수와 lift-off를 변수로 신호의 특성을 비교하고자 하였다. 실험 결과, 500, 1000, 1500 kHz를 사용하였을 때 notch 깊이가 증가할수록 신호의 진폭이 증가하는 것으로 나타났고, lift-off 변화에 따른 신호의 진폭은 선형적으로 감소하였다. 또한 용접부 결함은 probe와 시험체의 접촉면에 밀접한 관계가 있다. Probe와 시험체의 접촉면이 양호한 경우 검출감도가 우수하고 그렇지 않은 경우에는 검출감도가 떨어지는 것을 알 수 있었다.

• 전기학회논문지
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• 제62권3호
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• pp.431-436
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• 2013

A neutral section is installed around feeding substation(SS) and sectioning post(SP) that M phase and T phase are isolated in AC feeding system. Electric Train under "Notch-OFF" is operated by inertia within the neutral section. It causes disturbing the operation of electric trains for speed drop and driver's mistakes. A automatic changeover system with thyristor recently have taken under development. In the paper, it is introduced the configuration of train detection system and performance testing on automatic changeover system..

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.893-896
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• 2005

This paper describes Low Noise Amplifier(LNA) and Single Balanced Mixer(SBM) with monolithic image rejection notch filter using 0.5um MESFET process. LNA, Notch filter, and SBM were integrated on a chip. This chip does not need off chip SAW filter, thereby reducing the overall cost and system volume. The LNA with Notch filter provides a gain of 15dB, noise figure of 1.2dB, and image rejection ratio of -74dB. The SBM has a conversion gain of 6dB.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.498-506
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• 2010

The neutral section was installed in order to prevent conflict with different phase angle source in electric railway catenary system. The speed of electric train reduced due to coasting operation by notch off when it passed the neutral section. And, the catenary wire was damaged and the accident might be happened because of the arc generation when the electric train passed the neutral section with notch on condition. This project has a goal to develop the automatic changeover system using by noncontactless semiconductor device in neutral section of catenary system so that the train pass as notch-on condition. In this first year, we obtain as following results such as domestic and international systems applications and completion requirements, development and analysis of stability for automatic changeover system, design of static switching device on automatic changeover system in neutral section and drawing up interface design and specifications according to equipment.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.634-643
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• 2011

The neutral section was installed in order to prevent conflict with different phase angle source in electric railway catenary system. The speed of electric train reduced due to coasting operation by notch off when it passed the neutral section. And, the catenary wire was damaged and the accident might be happened because of the arc generation when the electric train passed the neutral section with notch off condition. The inrush current of main transformer installed tiling train is analyzed during the operation of MCB(main circuit break) passing through the neutral section. The instantaneous waveform of load current were analyzed in case of powering and regenerative braking. Inrush current waveform with run of AC railway train showed that inrush current waveform and harmonics, the inrush current generated from main transformer in train has bad effects on power quality problem. In order to reduce these inrush currents, the MCB is connected when the phase angle of voltage is 90 degree. This paper is to measure inrush current and harmonics in main transformer of high speed train in neutral section of electric railway. This measurement report is used to control minimum inrush current in algorithm and power phase angle.

• 한국전자파학회논문지
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• 제11권8호
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• pp.1313-1321
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• 2000

본 논문에서는 필터의 설계 및 구현이 용이하고 소형화가 가능한 새로운 구조의 고온초전도 마이크로스트립 형태의 의사 집중상수 소자 공진기를 제안하였다. 또한, 공진기들 사이의 비 인접 결합을 이용하여 notch를 갖는 필터특성의 7-극 대역통과 필터를 설계, 제작하였다. 7-극 notch를 갖는 필터는 두께 0.5mm, 유전율 23.5의 $LaAlO_{3}$ 기판상에 YBCO를 양면 증착하여 제작하였다. 측정결과, 절대 온도 20K에서 중심 주파수 1774MHz 차단대역(cut-off-band)에서 33㏈감쇠를 나타내었다.

• 전자공학회논문지
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• 제53권2호
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• pp.36-44
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• 2016

본 논문에서는 $0.18{\mu}m$ CMOS 공정을 이용하여 WBAN(Wireless Body Area Network)용 IR-UWB(Impulse Radio Ultra Wide Band) RF 송수신기를 제안한다. 설계된 송수신기는 3-5GHz UWB low band를 지원하며 OOK(On-Off Keying) 변조 방식을 사용한다. 수신기는 복잡도와 소모 전력을 줄이기 위해서 비동기식 에너지 검출 방식을 사용하였다. 원하지 않는 잡음을 제거하고 감도를 개선하기 위하여 RF active notch filter가 내장되어 있다. VCO 기반의 수신기는 switch mechanism을 사용하였다. 사용된 switch mechanism은 소모 전력을 줄이고 VCO leakage를 최소화 할 수 있다. 또한, 중심주파수가 변해도 항상 동일한 spectrum mask를 가진다. 측정된 수신기의 감도는 3.5 GHz의 중심주파수에서 1.579 Mbps의 전송 속도를 가질 때 -84.1 dBm을 가진다. 송신기와 수신기는 각각 0.3 nJ/bit, 41 mW의 소모 전력을 사용한다.

• 한국산업정보학회논문지
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• 제18권1호
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• pp.11-17
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• 2013

A design method to achieve multiple band-rejection characteristics in a wideband circular slot antenna is presented. First, a wideband circular slot antenna fed by a coplanar waveguide is designed to operate in the frequency range between 2.3 and 11GHz, which covers WLAN, WiBro, WiMAX, and UWB frequency bands. Next, resonant frequency variations of rejection bands are examined with respect to different slot locations and lengths when slots are inserted on the ground conductor and the circular patch of the antenna. When arc-shaped slots are placed close to the circular transition from a feeding part, multiple notch bands are obtained. In this case, a half of the guided wavelength of the first notch band corresponds to the slot length and other notch bands are integer-multiple of the first band. Single notch band can be obtained when the slot is located off the transition part. Based on this study, a wideband circular slot antenna with five band-rejection frequency bands at 2.45, 3.5, 4.9, 7.35, and 9.8GHz is designed and fabricated. The first arc-shaped slots are located in the ground conductor close to the circular transition from a feeding part to generate notch bands at 2.45, 4.9, 7.35, and 9.8GHz, while the second slot for 3.73 GHz is placed on top side in the circular patch. The proposed design method is validated by good agreement between the simulated and measured results.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.918-923
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• 2011

On AC railway systems, the neutral sections are installed in front of substations and sectioning posts in order to avoid crash between power that have differing phases. In case railway vehicles pass through these neutral sections, it is necessary for them to switch to coasting driving by notch-off. This may reduce speed of the vehicles, resulting lowered train operation efficiency. The usage of automatic power switching systems makes it possible to pass neutral sections at notch-on, enhancing operation efficiency so that it is appropriate for high-speed railway applications. This paper introduces a simulator that assesses efficiency of automatic power switching systems in neutral sections. The is composed of a power supply system, electric railway vehicles, thyristor switches, and traction motors.