• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.275-276
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• 2006

선박 및 해양기자재의 안전 진단을 위한 기존의 기술은 접 센서(point sensor)를 이용한 변형률 측정 기술이 대부분이라 할 수 있다. 본 논문은 기존의 기술보다 효율적으로 응용될 수 있는 광섬유 센서를 이용한 분포 개념의 온도 및 변형률 측정(DTSS: Distributed Temperature & Strain Sensing) 기술에 대해 소개하고 있다. 이 기술은 선체 응력 모니터링, 해양 구조물 안전진단, subsea flowline 모니터링, platform의 riser 안정성, umbilical 모니터링 등에 활용될 수 있다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1332-1335
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• 2003

This paper presents the enhancement of oxygen transfer efficiency using the vibrating intravascular lung assist device (VIVLAD) in in-vitro experiments for patients having chronic respiratory problems. The test section was a cylinder duct with the inner diameter of 30 mm. The flow rate was controlled by the pump and monitored by a built-in flow meter. The vibration apparatus was composed of a piezo-vibrator, a function generator. and a power amplifier. The direction of vibration was radial to the fluid flow. Gas flow rates of up to 6 l/min through the 120-cm-Jong hollow fibers have been achieved by exciting a piezo-vibrator. The output of PVDF sensor were investigated by various frequencies in VIVLAD. The experimental results showed that VIVLAD would be enhance oxygen transfer efficiency.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.2
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• pp.76-83
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• 2000

A study on the robust control of a composite beam with a distributed PVDF sensor and piezo-ceramic actuator is presented in this paper. $1^{st}$ and $2^{nd}$ natural frequencies are considered in the modeling, because robust control theory which has robustness to structured uncertainty is adopted to suppress the vibration. If the controllers designed by $H_{\infty}$ theory do not satisfy control performance, it is improved by $\mu$-synthesis method with D-K iteration so that the $\mu$-controller based on the structured singular value satisfies the nominal performance and robust performance. Simulation and experiment were carried out with the designed controller and the verification of the robust control properties was presented by results.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.411-414
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• 2000

Optical Triangulation Probes (OTPs) are widely used for their simple structure. high resolution, and long operating range. However, errors originating from speckle, inclination of the object, source power fluctuation, ambient light, and noise of the detector limit their usability. In this paper, we propose new design criteria for an error-reduced OTP. The light source module for the system consists of an incoherent light source and a multimode optical fiber for eliminating speckle and shaping a Gaussian beam Intensity profile. A diffuse-reflective white copy paper, which is attached to the object, makes the light intensity distribution on the change-coupled device(CCD). Since the peak positions of the intensity distribution are not related to the various error sources, a sub-pixel resolution signal processing algorithm that can detect the peak position makes it possible to construct an error-reduced OTP system

• Journal of the Korean Society for Precision Engineering
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• v.18 no.10
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• pp.148-153
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• 2001

Active control of flexural vibrations of smart laminated composite beams has been carried out using piezoceramic sensor/actuator and viscoelastic material. The beams with passive constrained layer damping hale been analyzed by formulating the equations of motion through the use of extended Hamilton's principle. The dynamic characteristics such as damping ratio and modal damping of the beam are calculated for various fiber orientations by means of iterative complex eigensolution method. This paper addresses a design strategy of laminated composite under flexural vibrations to design structure with maximum possible damping capacity.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1791-1793
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• 1997

Since Korea was initiated a industrialization, many transmission lines have been installed to meet the increasing demand for the electric power. In large city, underground transmission lines were widely installed because of the environmental issue. But there have been appeared many failures on the lines, such as the external scar of cable, a fire in the culvert, overheating of cable, and so on. There have been many studies to monitor them and improve the reliability of the power supply. As a method monitoring the lines, a DTS(Distributed Temperature Sensor) system is developed and applied. This system monitors the lines and predicts the failures, using a optical fiber sensor. This paper describes this DTS system and its application for the underground transmission lines.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.169-172
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• 2005

Today, peoples have much interest about safety while an abnormal weather phenomenon is weighted increased. R.C buildings are consisting of main loaded members. Concrete are brittle materials and they are which come to brittle fracture rapidly by progress of cracks. With the exchange of such research in inside and outside of the country, the structure measurement method of having used PZT and the optical fiber (FBG) will be the actual condition which has accomplished the stock. Specially, seismic activity that gives damage to construction and members happens in on time. Therefore, the purpose of this study is the fundamental research which detects damagesof main members using the compound sensor which consisted of the radio sensors of resistance, PZT, and FM system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.737-741
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• 2001

An illumination system by using sun light is optimally designed. The developing system consists of main controler for sun tracking, Cds sensor module, and light translation system based on optical fiber. A sun tracking algorithm is designed in such away that the illumination system stand with straight angle to the direction of sun within $\pm$2$^{\circ}$as permissible tolerance. To show the validity of the developed system, several experiments will be illustrated.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.151-152
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• 2006

Gas Insulated Switchgear 내부에서 발생되는 부분방전 검출을 위하여 다양한 UHF센서가 이용되고 있다. 그러나 출력단의 신호크기가 극히 미약하여 다단계 증폭과정과 아날로그/디지털 신호처리 기술들이 적용되고 있으며 이로 인한 신호 왜곡이 필연적이어서 그 해결방안이 다양하게 제시되고 있다. 하나의 방안으로서 UHF 출력신호를 광 신호 형태로 전송할 수 있는 광소자와 Optical Fiber의 장점을 이용하면 기존에 상용화되어 있으나 문제를 야기 시키는 신호처리 기술 대체가 가능하다. 본 논문에서는 GIS 진단 기술개발을 위하여 자체 개발된 광 기술을 적용하여 검출된 미세신호들의 왜곡 문제점 해결에 기여하고자한다.

• Journal of the Korean Geophysical Society
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• v.8 no.1
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• pp.7-14
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• 2005

Early detection in real-time response of slope movements ensures tremendous saving of lives and repair costs from catastrophic disaster. Therefore, it is essential to constantly monitor the performance and integrity of slope-stabilizing structures such as Rock bolt, Nail and Pile during or after installation. We developed a novel monitoring system using Fiber Bragg Grating (FBG) sensor. It's advantages are highly sensitivity, small dimension and electro-magnetic immunity. capability of multiplexing, system integrity, remote sensing - these serve real-time health monitoring of the structures. Real-time strain measurement by the signal processing program is shown graphically and it gives a warning sound when the monitored strain state exceeds a given threshold level so that any sign of abnormal disturbance on the spot can be easily perceived.