• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.11
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• pp.48-55
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• 2016

Ambient-light sensor system, which changes the brightness of a display as ambient light change, was studied to reduce the power consumption of the mobile applications such as note PC, tablet PC and smart phone. The ambient-light sensor system should be integrated on a display panel to improve the complexity and cost of mobile applications, so the ambient-light sensor and readout circuit was integrated on a display panel using low-temperature poly-silicon thin film transistors (LTPS-TFT). We proposed the new compensation method to correct the panel-to-panel variation of the ambient-light sensors, without additional equipment. We designed and investigated the new readout circuit with the proposed compensation method and the analog-to-digital converter for the final digital output of ambient light. The readout circuit has very simple structure and control timing to be integrated with LTPS-TFT, and the input luminance ranges from 10 to 10,000 lux. The readout rate is 100 Hz, and maximum differential non-uniformity with 20 levels of the final output below 0.5 LSB.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.129-132
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• 2008

손목에 착용하여 맥파와 산소포화도 등의 정보를 측정할 수 있는 유비쿼터스 광센서를 개발하였다. 유비쿼터스 광센서의 SNR의 향상을 위해 660nm의 LD와 904nm의 LD를 사용하였으며, 2종류의 LD는 각각 PD를 중심으로 $120^{\circ}$로 배치하였다. 또한 정확한 신호의 측정 및 분석을 위해 LabVIEW를 사용하였다. 제작된 광센서는 정확한 맥박 및 산소포화도의 측정이 가능하였으며 Beer-Lambert 곡선과 부합하여, 구성 및 설계가 정확함을 알 수 있다.

• The KIPS Transactions:PartC
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• v.13C no.3 s.106
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• pp.311-316
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• 2006

We propose the optical sensor network using optical CDMA with bipolar receiver and modified Pseudorandom Noise codes which are widely used in the wireless communication network. We numerically analyze the performances in the optical sensor network. In the proposed network, multiple access interferences between two sensors are suppressed by performing synchronization between the optical encoder and the optical decoder and adjusting the delay times of optical delay lines. Numerical simulations confirm that the performance can be acquired by suppressing the beat noise among optical signals as the number of sensors increases.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.3
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• pp.171-177
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• 2007

In this paper, we have designed and implemented an optical signal processor in order to use in a fiber-optic current CT for electric equipments where its properties were discussed. The fabricated optical signal processor is used to reduce a measurement current error that induced by the effects of intensity variation in the optical output signal due to losses coming from optical components or polarization variation in a PFOCS. Also, the optical signal processor was fabricated in compact/lightweight with unification of opto-electronic transducer part, analog signal process part, and real-time measurement part consisted of a level shift and ${\mu}-processor$. The experiment of optical signal processor has been performed in the range of $0{\sim}7,500A$ using the PFOCS made all fiber-optic components. As a result of experiment, the linearity error of measurement current is less than 1.7% and its average error is less than 0.3% in the range of $1,000A{\sim}7,000A$.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.192-193
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• 2003

광센서로 이용되는 광섬유 브라고 격자(이하 FBG)는 주변 환경에 대한 반응을 공진파장의 이동으로 나타내기 때문에 이것을 측정하기 위해서는 광 스펙트럼 분석기(OSA)가 반드시 필요하다 그러나 상용화된 광 스펙트럼 분석기는 고가이며 부피가 커서 광섬유 격자가 광센서로 상용화되는데 걸림돌이 되어 왔다. 이런 단점을 보완하기 위해서 많은 연구가 진행되어 왔으며 그 중에서 가장 잘 알려진 기술로는 Mach-Zehnder Inteferometer(MZI) 같은 간섭계를 이용한 방법과 Fabry-Perot (FP) filter, acousto-optic filter, FBG-based filters 등과 같은 변조기를 사용하여 광신호를 전기 신호로 바꿔 실시간으로 측정하는 방법들이 있다. (중략)

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.6
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• pp.31-38
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• 2009

To improve the image quality and lower the power consumption of the mobile applications, it is the one of the best candidate to control the backlight unit of the LCD module with ambient light. Ambient light sensor and readout circuit were integrated in LCD panel for the mobile applications, and we designed them with LTPS TFT. We proposed noble start-up correction in order to correct the variation of the photo sensors in each panel. We used time-to-digital method for converting photo current to digital data. To effectively merge time-to-digital method with start-up correction, we proposed noble dual slope correction method. The entire readout circuit was designed and estimated with LTPS TFT process. The readout circuit has very simple and stable structure and timing, so it is suitable for LTPS TFT process. The readout circuit can correct the variation of the photo sensors without an additional equipment, and it outputs the 4-levels digital data per decade for input luminance that has a dynamic range of 60dB. The readout rate is 100 times/sec, and the linearity error for digital conversion is less than 18%.

• Journal of Sensor Science and Technology
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• v.11 no.6
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• pp.365-370
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• 2002

The jumping ring apparatus described in this study is used to demonstrate and educate the effects of electromagnetic induction. Placing an aluminum ring over the core and switching on AC source causes the ring to jump in the air due to induced currents in the ring producing a magnetic field opposed to that produced in the core. This force is a function of flux density, ac current of ring and levitated height of the ring. Using photo sensor arrays, detect the ring position and represent the position of the ring to analog voltage for an education performance. This paper presents modelling of the jumping ring system and shows how does control signal generate in order to follow desired position.

• Journal of the Korean Society of Radiology
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• v.15 no.1
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• pp.1-7
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• 2021

In order to acquire an image in a positron emission tomography, it is necessary to draw the position coordinates of the scintillation pixels of the detector module measured at the same time. To this end, in a detector module using a plurality of scintillation pixels and a small number of photosensors, it is necessary to obtain a flood image and divide a region of each scintillation pixel to obtain a position of a scintillation pixel interacting with a gamma ray. Alternatively, when the number of scintillation pixels and the number of photosensors to be used are the same, the position coordinates for the position of the scintillation pixels can be directly acquired as digital signal coordinates. A method of using a plurality of scintillation pixels and a small number of photosensors requires a process of obtaining digital signal coordinates requires a plurality of photosensors and a signal processing system. This complicates the signal processing process and raises the cost. To solve this problem, in this study, we developed a method of obtaining digital signal coordinates without performing the process of separating the planar image and region using a plurality of flash pixels and a small number of optical sensors. This is a method of obtaining the position coordinate values of the flash pixels interacting with the gamma ray as a digital signal through a look-up table created through the signals acquired from each flash pixel using the maximum likelihood function. Simulation was performed using DETECT2000, and verification was performed on the proposed method. As a result, accurate digital signal coordinates could be obtained from all the flash pixels, and if this is applied to the existing system, it is considered that faster image acquisition is possible by simplifying the signal processing process.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.106-106
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• 2012

인체 내 소량의 생체성분을 감지하는 바이오센서 기술은 질병 진단뿐만 아니라 예방 및 관리로 의료서비스 확대 및 의료비 감소 효과를 가져올 수 있는 기술이다. 광 바이오센서는 광학적인 측정방법을 이용하여 다양한 생화학물질들의 상호 반응을 검출해 낼 수 있는 바이오센서로 현재 활발하게 연구가 진행되고 있다. 일반적으로 형광물질, 발색물질 등의 발광물질을 인식물질에 표지하여 인식물질과 분석물질과의 반응 유무를 표지된 발광물질의 광 신호를 감지하여 분석물질을 검출해내는 표지식 광 바이오센서 기술이 상용화되고 있다. 그러나 이러한 분석 방법은 민감도는 우수하지만 분석 시간이 매우 느리고, 고가의 분석 장비를 필요로 하는 단점들을 가지고 있다. 이러한 단점들을 극복하기 위하여 생화학 반응 유무를 표지물질 없이 광학적 방식으로 직접 측정해내는 비 표지식 광 바이오센서 기술이 최근 들어 많이 연구되고 있다. 본 논문에서는 비표지식이면서 분광기 없이 분석 가능한 공진 반사광 바이오센서 기술에 관한 내용을 소개하고자 한다. 공진 반사광 바이오센서는 광파장 이하의 주기를 가진 주기적 공진 격자 표면에서 일어나는 항원-항체 반응에 대한 공진 반사 파장을 측정하여 원하는 바이오물질을 고감도로 검출할 수 있는 바이오센서이다. 또한, 인체 내장을 위하여 플렉시블 기판 상에 GaN LED를 집적하여 전립선암 바이오 마커 검출에 대한 결과를 소개하고자 한다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.2
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• pp.22-27
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• 2011

Rain sensor detecting the presence of rain outside windshield glass of automobile by receiving scattered light from rain drops is proposed. Rain sensor using windshield glass as light waveguide required precision optical apparatus to inject light signal into windshield glass, and it was susceptible to outside shock and vibration, resulting malfunction, which altered optical coupling ratio. Proposed rain sensor, which detected scattered light from rain drops outside optical waveguide, did not require optical components because it did not need to inject light signal into light waveguide. This was advantageous because the sensor was less effected by shock and vibration. Fabricated rain sensor using scattered light outside waveguide responded not only to rain drops but also mist particles under simulated rain conditions using spraying nozzle, thus it showed prospects as rain sensor for automobile application.