• 센서학회지
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• 제29권3호
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• pp.149-155
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• 2020

In this study, we employed Manchester code for illumination control and flicker prevention of the light-emitting diode (LED) used in a visible light communication (VLC) system. In the VLC transmitter, the duty factor of the Manchester code was utilized for illumination control; in the VLC receiver, the spike signal from an RC-high pass filter was utilized to recover the transmitted signal whilst suppressing the 120-Hz noise arising from adjacent lighting lamps. Instead of the clock being transmitted in a separate channel, a syncmark signal was transmitted in front of each data byte and used as the reference time for transforming the Manchester code to non-return-to-zero (NRZ) data in the receiver. In experiments, the LED illumination was controlled in the range of approximately 12-84% of the constant wave (CW) light via changing of the duty factor from 10% to 90%. This scheme is useful for constructing indoor wireless sensor networks using LED light that is flicker-free and presents capability for illumination control.

• 대한의용생체공학회:의공학회지
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• 제30권6호
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• pp.503-509
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• 2009

The development of technology has led to ubiquitous health care service, which enables many patients to receive medical services anytime and anywhere. For the ubiquitous health care environment, real-time measurement of biomedical signals is very important, and the medical instruments must be small and portable or wearable. So, such devices have been developed to measure biomedical signals. In this study, we develop the biomedical monitoring device which is sensing the PPG signal, one of the useful signal in the field of ubiquitous healthcare. We design a watch-like biomedical signal monitoring system without a finger probe to prevent the user's inconvenience. This system obtains the PPG from the radial artery using a sensor in the wrist band. But, new device developed in this paper is easy to get the motion artifacts. So, we proposed new algorithm removing the motion artifacts from the PPG signal. The method detects motion artifacts by changing the degree of brightness of the light source. If the brightness of the light source is reduced, the PPG pulses will disappear. When the PPG pulses have disappeared completely, the remaining signal is not the signal that results from the changing blood flow. We believe that this signal is the motion artifact and call it the noise reference signal. The motion artifacts are removed by subtracting the noise reference signal from the input signal. We apply this algorithm to the system, so we can stabilize the biomedical monitoring system we designed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.508-510
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• 1995

A fiber-optic pressure sensor is fabricated with a photoelastic glass material. To remove the influence of external pertubation along the optical fiber, a new referencing technique is proposed by using two light sources. LED with 870nm wavelength is used as light source for reference signal, and LED with 660nm wavelength is used as light source for modulation signal. The fiber-optic pressure sensor system shows good linearity within the pressure range of 0 to 5 $kg/cm^2$.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 The Third Asian Fuzzy Systems Symposium
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• pp.423-425
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• 1998

An optical system which can autonomously form and display an impression of a picture made up by many figures has been developed. This system consists of optical fuzzy-neurons which calculate the correlation between the input picture and the reference image by incoherent optics. The calculated signal is applied to an amplifier whereby the output signal increases, then decreases according to increase of the input signal . These outputs are synthesized, and are used for changing the position where the system gaze on a part of the input picture by light beam. In this system, the light intensity used for gazing changes chaotically, The attractor drawn from the change of light intensity corresponds to the impression of the picture. This paper shows the results that are calculated by the numerical simulation. The system has been simulated to express the impression for a picture formed by 4figures.

• 한국산업융합학회 논문집
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• 제26권5호
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• pp.785-792
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• 2023

Because hyperspectral imaging provides detailed spectral information across a broad range of wavelengths, it can be utilized in numerous applications, including environmental monitoring, food quality inspection, medical diagnosis, material identification, art authentication, and crime scene analysis. However, hyperspectral images often contain various types of distortions due to the environmental conditions during image acquisition, which necessitates the proper removal of these distortions through a data preprocessing process. In this study, a preprocessing method was investigated to effectively correct the distortion caused by artificial light sources used in indoor hyperspectral imaging. For this purpose, a halogen-tungsten artificial light source was installed indoors, and hyperspectral images were acquired. The acquired images were then corrected for distortion using a preprocessing that does not require complex auxiliary equipment. After the corrections were made, the results were analyzed. According to the analysis, a statistical transformation technique using mean and standard deviation with reference to a reference signal was found to be the most effective in correcting distortions caused by artificial light sources.

• 한국항행학회논문지
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• 제23권1호
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• pp.61-68
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• 2019

블랙박스 본체를 회수하지 않고도 블랙박스의 정보나 수중 장비의 기록된 정보 등을 회수할 수 있도록 빛을 이용하는 수중 무선 광 통신 시스템은 매우 요긴하다. 본 논문에서는 탁도가 높은 천해환경에서 수중 가시광 통신시 발생하는 노이즈 원인을 분석하고 이러한 환경에서도 노이즈를 효과적으로 제거하면서도 광 검출신호의 최대 전압 스윙을 향상시킬 수 있는 기준신호 기반의 광 검출 센서 기술을 연구하였다. 그리고 개발한 통신 시스템의 성능을 입증하기 위해 광 무선통신 시스템을 제작하고 탁한 해수가 담긴 수조에서 송수신 시험을 수행하여 개발한 광 무선통신 기법이 실제로 효과가 있음을 검증하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.718-721
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• 2003

It is often desirable that manufacturers and users can convert the reference white of display into the preferred color temperature by controlling the color temperature that is one of representative color characteristics of a light source. Accordingly, this paper proposes an efficient method of color compensation for displaying the uncalibrated video signal in PDP-TV and is also shown to be successfully coupled with flexible color temperature conversion based on the signal processing technique.

• 한국생산제조학회지
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• 제21권5호
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• pp.814-823
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• 2012

Fluctuation of light intensity from the keyhole becomes more significant in full penetration welding than partial penetration welding, since the plasma produced in the keyhole can escape from the rear side of the keyhole. The plasma optical radiation emitted during Nd:YAG laser welding of S45C steel samples has been detected with a Photodiode and analyzed under different process conditions. As the results, the BOP was performed for welding, behavior of plasma, spatter or plume was monitored to determine the reference signal. Then, random combination was made for comparison with the reference signal, which aimed at verifying reliability of the welding monitoring system that this study intended to develop.

• 조명전기설비학회논문지
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• 제18권4호
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• pp.34-40
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• 2004

본 연구에서는 인체에 무해하며, 고분해능 측정과 저가격화 및 소형으로 제작이 가능한 광섬유를 이용한 광영상단층촬영기 제작에 관한 것이다. 시스템의 기본원리는 마이켈슨 간섭계를 이용한 것으로서 광섬유를 이용하여 간섭계를 구성하였다. 시스템의 구성으로는 광원은 분해능 및 측정범위를 고려하여 1,300(nm) 중심파장을 가지며 대역폭이 35(nm)인 상용제품의 SLD(Superluminersent diode)를 사용하였으며, 샘플내부의 영상을 검출하기 위한 간섭신호 검출방법은 기준거울이 선형적으로 이동하여 광경로를 일치하는 광지연선로를 구성하였다. 그리고 간섭계는 단일모드 광섬유를 이용하여 마이켈슨 간섭계를 구성하였으며, 스캐너는 시준기를 이용하여 샘플에 대한 초점을 고정하였으며, 스텝모터를 이용하여 샘플에 대한 횡단방향의 이동을 통해 샘플의 2차원 단층영상을 측정하도록 하였다. 수광부는 소신호인 간섭신호를 검출하기 위하여 감도가 뛰어나면 잡음특성이 우수한 800-1,700(nm) 측정범위의 광검출기를 사용하였다. 신호처리부에서 간섭신호의 포락선 신호만을 검출하기 위하여 증폭 및 필터링 하여 A/D 변환을 거친 후 영상검출 프로그램을 통해 실시간으로 단층영상을 나타내도록 하였다. 측정결과 분해능은 약 30($\mu\textrm{m}$)로서 이론식과 일치함을 확인하였으며, 샘플을 이용한 단층촬영에서 실시간으로 양파조직의 조직형태를 측정하였다.

• Journal of the Optical Society of Korea
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• 제17권4호
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• pp.317-322
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• 2013

We have proposed and demonstrated a low numerical aperture technique to measure the depth of through silicon vias (TSVs) using white-light scanning interferometry. The high aspect ratio hole like TSV's was considered to be impossible to measure using conventional optical methods due to low visibility at the bottom of the hole. We assumed that the limitation of the measurement was caused by reflection attenuation in TSVs. A novel interference theory which takes the structural reflection attenuation into consideration was proposed and simulated. As a result, we figured out that the low visibility in the interference signal was caused by the unbalanced light intensity between the object and the reference mirror. Unbalanced light can be balanced using an aperture at the illumination optics. As a result of simulation and experiment, we figured out that the interference signal can be enhanced using the proposed technique. With the proposed optics, the depth of TSVs having an aspect ratio of 11.2 was measured in 5 seconds. The proposed method is expected to be an alternative method for 3-D inspection of TSVs.