• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1465-1467
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• 2004

Compared with other transport means, safety and timeliness are the merits of railways. Unexpectedly when accident happens, much time and human strength are required to cope with the accident. And for swift recovery, systematic rehabilitation is needed. Recently using MTS(Moving picture Transmission System), we can perform accident rehabilitation and recording work efficiently. MTS is the device that transmits continuous picture information from accident field to control center. e are developing the appropriate system to railway situation to make use of the existing information communication technology, processing technology of video-tex, super high speed transmission technology through fiber-optic, copper cable and network description of information Technology, etc. If these communication-based can technologies are applied to railway system, railway managers can control the accident by inspecting the picture of accident field and can contribute to the safe train operation and the improvement of railway management. In this paper, we investigate the connecting methods when optical fiber is used for moving picture data transmission of train accidents, and its problems. And, we validate MTS's performance through about 28km section of field test.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.244-246
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• 2004

Compared with other transport means, safety and timeliness are the merits of railways. Unexpectedly when accident happens, much time and human strength are required to cope with the accident. And for swift recovery, systematic rehabilitation is needed. Recently using MTS(Moving picture Transmission System), we can perform accident rehabilitation and recording work efficiently. MTS is the device that transmits continuous picture information from accident field to control center. We are developing the appropriate system to railway situation to make use of the existing information communication technology, processing technology of video-tex, super high speed transmission technology through fiber-optic, copper cable and network description of information Technology, etc. If these communication-based can technologies are applied to railway system, railway managers can control the accident by inspecting the picture of accident field and can contribute to the safe train operation and the improvement of railway management. In this paper, we investigate the connecting methods when optical fiber is used for moving picture data transmission of train accidents, and its problems. And, we validate MTS's performance through about 28km section of field test.

• 한국전자통신학회논문지
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• 제9권4호
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• pp.469-474
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• 2014

전신주에 설치된 난립 통신선로의 포설 상태를 모니터링하고, 정비용 부가정보 수단을 제공할 수 있는 현장 모니터링 지원 시스템을 개발한다. 공중선로 정비 지원을 위한 모니터링 모듈 및 정보 처리 어플리케이션을 적용 임베디드 시스템을 제작한다. 본 연구에서는 정부의 공중선 정비 종합계획에 따라 작업 안전사고 예방 지원 장치로 보급하기 위한 대도시 공중선 정비 사업에 즉시 활용하고, 고소 공사 편의 및 작업자의 정비 효율성을 제고하는데 목적을 둔다.

• Smart Structures and Systems
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• 제18권6호
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• pp.1203-1215
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• 2016

When strain sensing cables are under long-term stress and cyclic loading, creep may occur in the jacket material and each layer of the cable structure may slide relative to other layers, causing fatigue in the cables. This study proposes a device for testing the fatigue characteristics of three types of cables operating under different conditions to establish a decay model for observing the patterns of strain decay. The fatigue characteristics of cables encased in polyurethane (PU), GFRP-reinforced, and wire rope-reinforced jackets were compared. The findings are outlined as follows. The cable strain decayed exponentially, and the decay process involved quick decay, slow decay, and stabilization stages. Moreover, the strain decay increased with the initial strain and tensile frequency. The shorter the unstrained period was, the more similar the initial strain levels of the strain decay curves were to the stabilized strain levels of the first cyclic elongation. As the unstrained period increased, the initial strain levels of the strain decay curves approached those of the first cyclic elongation. The tested sensing cables differed in the amount and rate of strain decay. The wire rope-reinforced cable exhibited the smallest amount and rate of decay, whereas the GFRP-reinforced cable demonstrated the largest.

• International Journal of Aeronautical and Space Sciences
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• 제17권1호
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• pp.37-44
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• 2016

Optical fiber temperature sensing systems have incomparable advantages over traditional electrical-cable-based monitoring systems. However, the fiber optic interrogators and sensors have often been rejected as a temperature monitoring technology in real-world industrial applications because of high cost and over-specification. This study proposes a multiplexed fiber optic temperature monitoring sensor system using an economical Optical Time-Domain Reflectometer (OTDR) and Hard-Polymer-Clad Fiber (HPCF). HPCF is a special optical fiber in which a hard polymer cladding made of fluoroacrylate acts as a protective coating for an inner silica core. An OTDR is an optical loss measurement system that provides optical loss and event distance measurement in real time. A temperature sensor array with the five sensor nodes at 10-m interval was economically and quickly made by locally stripping HPCF clad through photo-thermal and photo-chemical processes using a continuous/pulse hybrid-mode laser. The exposed cores created backscattering signals in the OTDR attenuation trace. It was demonstrated that the backscattering peaks were independently sensitive to temperature variation. Since the 1.5-mm-long exposed core showed a 5-m-wide backscattering peak, the OTDR with a spatial resolution of 40 mm allows for making a sensor node at every 5 m for independent multiplexing. The performance of the sensor node included an operating range of up to $120^{\circ}C$, a resolution of $0.59^{\circ}C$, and a temperature sensitivity of $-0.00967dB/^{\circ}C$. Temperature monitoring errors in the environment tests stood at $0.76^{\circ}C$ and $0.36^{\circ}C$ under the temperature variation of the unstrapped fiber region and the vibration of the sensor node. The small sensitivities to the environment and the economic feasibility of the highly multiplexed HPCF temperature monitoring sensor system will be important advantages for use as system-integrated temperature sensors.

• 로봇학회논문지
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• 제12권1호
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• pp.26-32
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• 2017

Previous shape sensors including bend sensors and optic fiber based sensors are widely used in various applications including goniometer and surgical robots. But theses sensors have large nonlinearity, limited in the range of sensing curvature, and sometimes are expensive. This study suggests a new concept of bend sensor using cable-conduit which consists of the outer sheath and the inner wire. The outer sheath is made of helical coil whose length of the central line changes as the sheath bends. This length change of the central line can be measured with the length change of the inner cable. The modeling and the experimental results show that the output signal of the proposed sensor is linearly related with the bend angle of the sheath with root mean square error of 5.3% of $450^{\circ}$ sensing range. Also the polynomial calibration of the sensor can decrease the root mean square error to 2.1% of the full sensing range.

• 한국소음진동공학회논문집
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• 제22권11호
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• pp.1089-1098
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• 2012

A faulting could be occurred at the end of deck by unexpected loads to bridge bearing after a bridge completion. Serviceability of bridges could be impaired by the faulting which is caused structural damage. Therefore, smart bridge bearing which can continuously observe the supporting points is needed. Some of bridge bearings have been developed for measuring vertical load and vertical displacement by installing sensors in the bearing. In those systems, however it is not easy to be replaced with new sensors when repairs are needed. In this study, the smart bridge bearing of which sensors can be replaced has been developed to overcome such a problem. In this study, strain signals were used for measuring both of vertical displacements and loads. FBG sensors(fiber optic Bragg-grating sensors) have been used for measurement of the strain signals since it is prevented from electronic noise by mediating light, enables the simplification of the measuring cable by multiple measurement, and is easy to place by lightweight and small size. The possibility of use was reviewed for smart bridge bearing based on FBG sensors through tests.

• 센서학회지
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• 제31권6호
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• pp.441-447
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• 2022

This study describes a novel method for detecting and measuring partial discharge (PD) on an electrical facility such as an insulated power cable or switchgear using fiber optic sensing technology, and a distributed acoustic sensing (DAS) system. This method has distinct advantages over traditional PD sensing techniques based on an electrical method, including immunity to electromagnetic interference (EMI), long range detection, simultaneous detection for multiple points, and exact location. In this study, we present a DAS system for PD detection with performance evaluation and experimental results in a simulated environment. The results show that the system can be applied to PD detection.

• 대한기계학회논문집A
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• 제38권3호
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• pp.235-241
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• 2014

심해 군사 작전에서 유도체의 타격 성능 향상은 모함과 유도체가 광 케이블을 통하여 안정적인 통신을 유지함으로써 가능하다. 이 때 광 케이블은 엉킴 및 절단과 같은 풀림 불량을 방지하기 위해 보호 튜브에 의해 보호된다. 또한 보호 튜브는 전단 핀에 의해 유도체와 연결되며, 전단 핀의 파손에 의해 유도체는 보호 튜브와 분리된다. 따라서 본 연구에서는 유도체 및 보호 튜브를 모델링하고, 유도체의 운동에 따른 보호 튜브의 풀림 거동을 분석하며 전단 핀에 작용하는 동적 하중을 예측한다. 유도체와 보호 튜브는 질점으로 구성하며, 일정 길이 구속으로 연결한다. 전단 핀에 작용하는 하중은 실험 결과와 비교 검증하며, 이를 바탕으로 보호 튜브의 거동을 예측한다.

• 한국정보통신학회논문지
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• 제13권11호
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• pp.2412-2418
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• 2009

FTTH 인프라 구축이 활성화됨에 따라 광섬유의 대역폭을 효과적으로 이용하기 위한 기술들이 활발히 연구되고 있다. 특히, 방송통신 융합 서비스에 대한 관심과 연구가 활발히 진행되면서 하나의 광섬유를 통해 다수의 방송 서비스를 수용할 수 있는 광 비디오 네트워크 단말장치(VONU: Video Optical Network Unit)의 연구가 요구되고 있다. 따라서, 본 연구에서는 비디오 광 송신장치에서 전광 변환된 디지털 및 아날로그 CATV(Community Antenna TeleVision) 방송 신호와 위성 안테나를 통해 수신되어 전광 변환된 위성방송 신호가 하나의 FITH 광 선로를 통해 전송되고 이를 광전 변환하여 출력하는 VONU를 개발한다. 본 연구에서 개발하는 VONU는 데이터통신 채널을 이용한 IPTV 방송과 함께 CATV, 위성방송 등 모든 방송 콘텐츠를 하나의 광섬유 코어를 통해 전송할 수 있기 때문에 경제적인 방송통신 융합 서비스의 구현이 가능해 진다. 그러나, 서비스 별로 별도의 광수신기를 사용할 경우와는 달리 서비스간 간섭, 신호 왜곡, 잡음비 증가 등에 따른 방송 품질 저하 등의 병존성 문제가 발생하기 때문에 이에 대한 문제를 해결하기 위한 기술들이 필수적이다. 따라서, 본 연구에서 제시하는 VONU는 이에 대한 해결방안을 제안한다.