• 대한전자공학회논문지SD
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• 제41권3호
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• pp.39-44
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• 2004

광섬유 브래그 격자 센서는 광섬유의 코어의 굴절률 변조에 의해서 제작되며, 이 센서는 외부의 스트레인에 따라 브래그 파장이 변화하게 된다. 본 논문에서는 광섬유 브래그 격자 센서를 파장 영역에서 신호처리 할 수 있는 방법에 대하여 연구하였다. SLD와 F-P 필터로 구성된 sweep 반도체 광원과 F P 필터내의 PZT의 히스테리시스 특성을 보상하기 위한 에탈론 필터와 장기 계측을 위해 절대 파장 기준으로 온도 안정된 광섬유 브래그 격자를 사용하였다. 콘크리트 흄관에서 FBG 센서의 스트레인 응답 특성을 전기저항 센서와 비교하였다. 그리고 광섬유 격자 센서를 이용하여 장거리 변위의 측정 가능성을 확인하였다.

• 한국전기전자재료학회논문지
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• 제35권2호
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• pp.165-171
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• 2022

The SiO₂/TiO₂ multilayer thin films used for narrow band pass filter were fabricated using E-beam evaporation method. The narrow band pass filter was used to enhance the resolution of spectroscopy and sensor applications with near infrared (NIR) light source. The narrow band pass filter with multilayer thin films were designed with Essential Macleod program. The multilayers of SiO₂/TiO₂ with 32 layers were deposited on the silicon encapsulation of IR with peak wavelength (λ_p) of 660 nm and NIR LEDs with λ_p of 830 nm, 880 nm, and 955 nm. After NIR light passed through the narrow band pass filter, the full width of half maximum of 33.4~48.6 nm became narrow to 20~24 nm owing to the absorption of photons with short or long wavelength of designed band of 20 nm. The SiO₂/TiO₂ band pass filter fabricated in this study can be used for sensor, optoelectronics, and NIR spectroscopy applications.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1656-1659
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• 2008

The reflective type color filter for the liquid crystal displays (LCD) was produced using cholesteric liquid crystal monomers whose phase is characterized by the unique optical features of selective reflection. Periodic micrometer scale hemi-spherical photoresist (PR) patterns were formed on glass substrates by thermal reflow method after photolithography. Cholesteric color filter films for red, green and blue light reflections were then produced and the viewing angle dependence was investigated and compared with that of reflected light on the non-patterned substrates.

• 한국멀티미디어학회논문지
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• 제20권11호
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• pp.1741-1749
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• 2017

In commercial digital-cameras, color-filter filters light according to wavelength range of color filter array (CFA) and the filtered intensities contain color information of light. Then, output data of CFA is transformed to final rendered image through demosaicing process. In image processing of digital-camera, the quality of the final rendered image is affected by optical cross talk of CFA, kind of CFA pattern etc. Basically, pattern of CFA plays important role in image quality of final image rendered by digital-camera. Therefore, an evaluation system capable of quantitatively evaluating CFA is needed. This paper proposes a novel evaluation system using existing and proposed image metrics for evaluating CFAs of digital-camera. Proposed CFA evaluation system consist of color difference in CIELAB and S-CIELAB, Structure SImilarity (SSIM), MTF50, moire starting point (MSP), and subjective preference (SP). MSP and SP are newly designed for the proposed evaluation system. Proposed evaluation system is expressed in polar coordinates to analyze the characteristics of CFA objectively and intuitively. Through simulations, we confirmed that proposed CFA evaluation system can objectively assess performance of developed CFAs.

• 전자공학회논문지B
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• 제32B권11호
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• pp.1481-1488
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• 1995

Due to the low loss, broadband and accurate short time delay properties of optical fiber, it has attracted as a delay medium for high speed and broad-band signal processing. In this paper, we consider the coherent optical fiber filter of IIR lattice structure, which uses coherent light sources and consists of directional couplers whose coupling coefficients are restricted between 0 and 1. Considering restrictions of directional coupler, the design formulae and condition for realibility of optical fiber filter of IIR lattice structure which makes the optimal use of optical signal energy are derived.

• Journal of Biosystems Engineering
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• 제30권5호
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• pp.299-305
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• 2005

This study was developed image processing algorithm for recognition of few teats of a cow in the image using black and white camera attached with infrared filter. Spectroscopic analysis was used for selection of a NIR filter to separate teats from udder skin in the image captured. To verify the performance of image processing algorithm was developed and NIR filter was selected, carried out an experiment with cows. NIR band-pass filter was used to pass the 975nm band of light spectrum. The image processing algorithm was developed could recognize all teats and the process time was 0.9 second to recognize the all teats and to acquire end position of teats.

• 한국산학기술학회논문지
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• 제19권7호
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• pp.36-41
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• 2018

미광증폭장비는 밤과 같이 어두운 환경에서 주로 가시광선 대역의 약한 빛을 증폭시켜 육안으로 관측할 수 있을 정도의 밝기로 만들어주는 장비이다. 이러한 방식은 어느 정도의 약한 빛이 존재하는 환경에서는 그 증폭 효과를 제대로 발휘하여 선명한 영상을 얻을 수 있지만, 달빛조차 존재하지 않는 극 저조도 환경에서는 기본적으로 증폭시킬 빛이 부족하여 출력 영상에 많은 노이즈로 인하여 화면의 선명도가 저하된다. 본 연구에서는 이러한 극 저조도 환경에서 발생하는 미광증폭 장비의 출력 노이즈를 다중 필터와 이방성 확산을 이용하여 화질을 개선하는 방법을 제안하였다. 실험을 위하여 극 저조도 조건에 맞는 환경을 구성한 상태에서 미광증폭장비의 출력 영상을 촬영한 후, 화질 개선을 위한 신호처리를 하였다. 신호처리를 위한 필터의 구성은 영상에 나타나는 주된 노이즈인 점 노이즈 제거와 가우시안 노이즈의 효과적인 제거를 위하여 메디안 필터, 위너 필터를 적용시킨 후 이방성 확산을 이용하였다. 실험 결과 화질이 개선됨을 육안으로 확인할 수 있었고, 정량 지표인 PSNR 및 SSIM으로 비교하여 측정한 방법에서도 모두 개선된 값을 보여주었다.

• Carbon letters
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• 제10권3호
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• pp.198-201
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• 2009

Among other filters such as light filter, wave filter, air filter, ultra filter and filter paper, a novel adsorption filter from thermostable polyester nonwoven fabrics immobilized with functional super activated carbon by means of quinoline soluble, activateable isotropic pitch binder were developed in this study. The activated carbon precursor is available in the market branded as coconut shell based activated carbon(CCS-AC) produced by Dongyang Carbon Co. Ltd. BET-surface area of this precursor was $1,355\;m^2/g$, after KOH-activation it increased over $2,970\;m^2/g$ and was named as super activated carbon. In the preliminary research, this precursor was impregnated with $PdCl_2$(0.188 wt%) $KMnO_4$(3 wt%) and redox-agent(CuCl2, 0.577 wt%) in order to promote TOF up to 100/h and Selectivity up 99% and patented as a functional AC for the ethylene adsorption. The enhancement of the isotropic pitch binder to the AC-immobilized adsorption filter was BET-surface area upgraded by $266\;m^2/g$ and promoted the Iodine- and MB-adsorption by 1.4 times, respectively and also micro pore wide ranges < $5{\AA}{\sim}30\;{\AA}$ >.

• 대한의용생체공학회:의공학회지
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• 제35권5호
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• pp.125-131
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• 2014

The purpose of this study is to verify the utility of reflected photoplethysmography sensor using two green light emitting diodes that influenced by ambient light. Recently it has been studied that green light emitting diode is suitable for light source of reflected photoplethysmography sensor at low temperature and high temperature. Another study showed that, green light is better for monitoring heart rate during motion than led light. However, it has a bad characteristic about ambient light noise. To verify the utility of reflected photoplethysmography sensor using green light emitting diode, this study measures the photoplethysmography signal that is distorted by ambient light and will propose a solution. This study has two parts of research method. One is measurement system that composed sensor and board. The sensor is made up PE-foam and Non-woven fabric for flexible sensor. The photoplethysmography signal is measured by measurement board that composed high-pass filter, low-pass filter and amplifier. Ambient light source is light bulb and white light emitting diode that has three steps brightness. Photoplethysmography signal is measured with lead II electrocardiography signal at the same time and it is measured at the finger and radial artery for 1 minute, 1000 Hz sampling rate. The lead II electrocardiography signal is a standard signal for heart rate and photoplethysmography signal that measured at the finger is a standard signal for waveform. The test is repeated 3 times using three sensor. The data is processed by MATLAB to verify the utility by comparing the correlation coefficient score and heart rate. The photoplethysmography sensor using two green light emitting diodes is shown better utility than using one green light emitting diode and red light emitting diode at the ambient light. The waveform and heart rate that measured by two green light emitting diodes are more identical than others. The amount of electricity used is less than red light emitting diode and error peak detectability factor is the lowest.

• 제어로봇시스템학회논문지
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• 제22권3호
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• pp.186-191
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• 2016

This paper addresses the development of 3D data acquisition system (3D scanner) based laser structured-light image. The 3D scanner consists of a stripe laser generator, a conventional camera, and a rotation table. The stripe laser onto an object has distortion according to 3D shape of an object. By analyzing the distortion of the laser stripe in a camera image, the scanner obtains a group of 3D point data of the object. A simple semiconductor stripe laser diode is adopted instead of an expensive LCD projector for complex structured-light pattern. The camera has an optical filter to remove illumination noise and improve the performance of the distance measurement. Experimental results show the 3D data acquisition performance of the scanner with less than 0.2mm measurement error in 2 minutes. It is possible to reconstruct a 3D shape of an object and to reproduce the object by a commercially available 3D printer.