• Transactions on Electrical and Electronic Materials
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• 제9권3호
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• pp.128-133
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• 2008

In this paper, in order to analyze property of frequency response in microphone using optical sensor, acousto-optic sensor system has been implemented. The capacitance microphone and fiber-optic transmission path type fiber-optic microphone (FOM) have weaknesses in directivity, size, weight, and price. However suggested optical microphone can be constituted by cheap devices, so it has many benefits like small size, light weight, high directivity, etc. Head part of optical microphone which is suggested in this paper is movable back and forth by sound pressure with the attached reflection plate. Operating point has also been determined by measuring the response characteristics. The choosing the point, which has maximum linearity and sensitivity has changing the distance between optical head and vibrating plate. We measured the output of the O/E transformed signal of the optical microphone while frequency of sound signal is changed using sound measurement /analysis program, "Smaart Live" and "USBPre", which are based on PC, and compared the result from an existing capacitance microphone. The measured optical microphone showed almost similar output characteristics as those of the compared condenser microphone, and its bandwidth performance was about 4 kHz at up to 3 dB.

• Composites Research
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• 제13권1호
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• pp.89-97
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• 2000

광섬유센서를 이용한 복합적층판의 피로손상 감지 및 진동측정, 그리고 스틸 보에 대한 충격위치 검출에 관한 연구가 수행되었다. 피로과정중의 신호는 복합재료 내에 삽입된 광섬유와 표면에 부착한 광강도형 광섬유센서, 그리고 스트레인게이지로부터 동시에 측정되었다. 진동감지 실험은 복합재료 보의 표면에 광섬유센서를 부착하여 자유진동 및 강제진동 신호를 취득하였다. 충격위치 검출에 관한 실험에서 충격위치는 충격에 의해 발생된 구조물의 진동이 두 센서에 도달하는 시간의 차를 이용하여 구할 수 있다. 광강도형 광섬유센서를 이용하여 반복 피로 신호를 잘 취득할 수 있었으며 스트레인게이지에 비하여 피로저항성이 우수함이 확인되었다. 광섬유센서는 갭센서와 동일하게 진동신호를 감지하였고 구조물에 가해진 충격위치를 비교적 정확히 검출할 수 있었다.

• 센서학회지
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• 제30권5호
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• pp.331-336
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• 2021

The Non-dispersive Infrared (NDIR) gas sensor has high selectivity, measurement reliability, and long lifespan. Thus, even though the NDIR gas sensor is expensive, it is still widely used for carbon dioxide (CO₂) detection. In this study, to reduce the cost of the NDIR CO₂ gas sensor, we proposed the new optical waveguide structure design based on ready-made gas pipes that can improve the sensitivity by increasing the initial light intensity. The new optical waveguide design is a structure in which a part of the optical waveguide filter is inclined to increase the transmittance of the filter, and a parabolic mirror is installed at the rear end of the filter to focus the infrared rays passing through the filter to the detector. In order to examine the output characteristics of the new optical waveguide structure design, optical simulation was performed for two types of IR-source. As a result, the new optical waveguide structure can improve the sensitivity of the NDIR CO₂ gas sensor by making the infrared rays perpendicular to the filter, increasing the filter transmittance.

• 한국생산제조학회지
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• 제21권4호
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• pp.541-546
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• 2012

This study investigates the detection system of oil pollution level using single optical fiber sensor. This study focus on sensing of oil pollution by moisture and iron powder which are representatives of oil pollution factor. In addition, It is placed that the water and iron powder as an oil pollution factor in the oil tank which is the oil circulation in. The oil pollution detection system was measured by the changing of intensity of light and sensing gap. The result of this experimentation not only confirmed the contamination by moisture volume in the oil tank from the section 190ppm to 540ppm, but also monitored the contamination by iron volume from the section 1200ppm to 3500ppm. This study confirmed effectiveness of this detection system using optical fiber sensor. There is expectations of measuring another section by various optical fiber sensor.

• 센서학회지
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• 제23권4호
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• pp.229-233
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• 2014

In this study, a V-grooved single-mode fiber along with optical time domain reflectometry (OTDR) as a quasi-distributed temperature sensor was investigated. The external medium used to fill the V-groove affects the optical mode. The V-groove was filled with ethylene vinyl acetate (EVA) because its transmittance was sensitive to temperature. The experimental results showed that the optical loss of the sensor varies with temperature, and the sensitivity depends on the depth of the V-groove.

• 센서학회지
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• 제21권2호
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• pp.151-155
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• 2012

We have investigated a refractive index sensor based on a cladded plastic optical fiber taper. The optical transmission and sensing characteristics of the device were illuminated in terms of ray optics. The sensor devices showed that the optical transmittance strongly depends on the refractive index of the external medium surrounding the tapered region.

• Current Optics and Photonics
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• 제5권3호
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• pp.238-242
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• 2021

In this paper, we present an in line plastic-optical-fiber (POF) temperature sensor based on intensity modulation. The in line POF temperature sensor is composed of a POF, including an in-fiber micro hole filled with reversible thermochromic material, the transmittance of which depends on temperature. The reversible thermochromic material was cobalt chloride/polyvinyl butyral gel. A cobalt chloride solution of concentration 30.8 mM was formulated using 10% water/90% ethanol (v/v) solution, and gelled by dissolving polyvinyl butyral in this solution. Four types of in line POF sensors, with in line micro holes of four different diameters, were fabricated to measure temperature in the range of 25 to 75 ℃. The output optical power of all of these in line POF temperature sensors was inversely proportional to the temperature; the relation between output power and temperature was approximately linear, and the sensitivity was proportional to the diameter of the in-fiber micro hole. The experimental results indicate that an in line POF sensor can be used effectively for measuring moderate temperatures.

• 정보처리학회논문지C
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• 제13C권3호
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• pp.311-316
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• 2006

양극성수신기와 무선통신에서 널리 사용되고 있는 PN(pseudo random noise) 부호를 수정하여 적용시킨 광 CDMA 방식을 사용한 광센서 네트워크를 제안한다. 광 센서 네트워크에서 특성을 수치적으로 분석하였다. 센서사이와 광 CDMA의 디코더에 광섬유형지연기를 사용하여 광 CDMA의 인코더와 디코더간 동기를 맞추고, 광지연기의 지연을 PN 부호의 칩폭보다 크게 하면 센서간 간섭잡음을 완전히 제거할 수 있다. 광 신호간 비트 잡음이 잡음전력을 지배하기 때문에 광센서 네트워크에 접속할 수 있는 광 센서의 수를 증가시키기 위하여 광신호간 비트 잡음을 억압하여야 한다.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.285-288
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• 2005

We propose a novel programmable miniature vision module based on a custom designed analog VLSI (aVLSI) chip. The vision module consists of the optical flow vision sensor embedded with commercial off-the-shelves digital hardware; in our case is the Intel XScale PXA270 processor enforced with a programmable gate array device. The aVLSI sensor provides gray-scale imager data as well as smooth optical flow estimates, thus each pixel gives a triplet of information that can be continuously read out as three independent images. The particular computational architecture of the custom designed sensor, which is fully parallel and also analog, allows for efficient real-time estimations of the smooth optical flow. The Intel XScale PXA270 controls the sensor read-out and furthermore allows, together with the programmable gate array, for additional higher level processing of the intensity image and optical flow data. It also provides the necessary standard interface such that the module can be easily programmed and integrated into different vision systems, or even form a complete stand-alone vision system itself. The low power consumption, small size and flexible interface of the proposed vision module suggests that it could be particularly well suited as a vision system in an autonomous robotics platform and especially well suited for educational projects in the robotic sciences.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.390-390
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• 2008

In this paper, we have designed and fabricated optical waveguides based on the Mach-Zehnder Interferometer (MZI) for application to sensor. The evanecent-wave sensor based on the MZI principle has sufficiently high sensitivity to measure the change of the refractive index on surface of a waveguide. The waveguides were optimized at a wavelength of 1550 nm and fabricated according to the design rule of 0.45 delta%, which is the difference of refractive index between the core and clad. The fabrication of MZI optical waveguides was performed by a conventional Planar Lightwave Circuit (PLC) fabrication process. The fabricated MZI optical waveguide device was measured. According to the measurement result, the insertion loss of MZI optical waveguide device was below 3.5 dB and the polarization dependent loss (PDL) was within 0.1dB. In addition, we analyzed optical properties of MZI sensor according to the refractive index change of the sensor arm.