• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.11
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• pp.1043-1051
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• 2007

The digital sun sensor calculates the incident sunlight angle using the sunlight image registered on a CMOS image sensor. In order to accomplish this, an exact center of the sunlight image has to be determined. Therefore, an accurate estimate of the centroid is the most important factor in digital sun sensor development. The most general method for determining the centroid is the thresholding method, and this method is also the simplest and easy to implement. Another centering algorithm often used is the image filtering method that utilizes image processing. The sun sensor accuracy using these methods, however, is quite susceptible to noise in the detected sunlight intensity. This is especially true in the thresholding method where the accuracy changes according to the threshold level. In this paper, a template method that uses the sunlight image model to determine the centroid of the sunlight image is suggested, and the performance has been compared and analyzed. The template method suggested, unlike the thresholding and image filtering method, has comparatively higher accuracy. In addition, it has the advantage of having consistent level of accuracy regardless of the noise level, which results in a higher reliability.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.7
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• pp.771-778
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• 2019

The traditional illuminance intensity detection method using a single sensor has a problem that uniformity of illuminance detection is deteriorated depending on the measurement position due to the narrow FOV characteristic. In order to overcome this problem, a method of detecting an average illuminance value through a plurality of illuminance sensors is used, but the complexity and detection error are increased. In this paper, we propose a illuminance intensity detection method based on a single image sensor with wide FOV. The proposed method can solve the problems such as system complexity and error increase of existing illuminance sensor. The test results show that the difference of average value is 12% using a illuminance sensor, 10.7% using five illuminance sensors, and 6.2% using an image sensor compared with the reference value using the color difference illuminometer. It is confirmed that the proposed method can easily and accurately detect the space illuminance with improved uniformity.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.191-196
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• 2021

In this paper, we implemented an image sensor module possible of detecting color temperature in an indoor environment. The color temperature information in the video information acquired by the image sensor was matched with a color difference illuminometer to produce an LUT. An algorithm was developed so that color temperature information according to the received RGB values can be automatically calculated. As a result of measuring the color temperature with an image sensor indoors, an accurate result of less than 5.91% was obtained compared to the reference value. It was confirmed that the uniformity of 23.5% or more was excellent compared to the color temperature measurement result using a color sensor.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.1
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• pp.111-116
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• 2006

In this paper, the image sensor using the a-Si:H TFT is proposed. The optimum amorphous silicon thin film is deposited using plasma enhanced chemical vapor deposition (PECVD). TFT and photodiode both with the thin film are fabricated and form image sensor. The photodiode shows that Idark is $10^{-12}A$, Iphoto is $10^{-9}A$ and Iphoto/Idark is $10^3$, respectively. In the case of a-Si:H TFT, it indicates that Ion/Ioff is $10^6$, the drain current is a few ${\mu}A$ and Vth is $2\~4$ volts. For the analysis on the fabricated image sensor, the reverse bias of -5 voltage in ITO of photodiode and $70{\mu}sec$ pulse in the gate of TFT are applied. The image sensor with good property was conformed through the measured photo/dark current.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.547-549
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• 2002

영상을 동반한 통신이 일반화되면서 CMOS 이미지센서를 장착한 저렴한 영상장치의 수요가 증대되었다. 하지만 CMOS이미지 센서는 CCD센서에 비해 화질이 좋지 않으므로 이를 개선해주는 전처리단계의 중요성이 더욱 부각되었다. 본 논문에서는 CMOS 이미지 센서에 의해 포획된 동영상을 실시간으로 처리하여 화질을 개선하는 ISP를 구현하고 시뮬레이션하였다. ISP의 여러 단계 중 Color Interpolation에 중점을 두어 여러 알고리즘을 보이고 비교／분석하여 각 상황에 맞는 알고리즘을 제시하였다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.3
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• pp.62-70
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• 2011

Nowadays image sensor is an essential component in many multimedia devices, and it is covered by a color filter array to filter out specific color components at each pixel. We need a certain algorithm to combine those color components reconstructed a full color image from incomplete color samples output from an image sensor, which is called a demosaicking process. Most existing demosaicking algorithms are developed for ideal image sensors, but they do not work well for the practical cases because of dissimilar characteristics of each sensor. In this paper, we propose a new demosaicking algorithm in which the color filter characteristics are fully utilized to generate a good image. To demonstrate significance of our algorithm, we used a commerically available sensor, CBN385B, which is a sort of Honeycomb-style CFA(Color Filter Array) CCD image sensor. As a performance metric of the algorithm, PSNR(Peak Signal to Noise Ratio) and RGB distribution of the output image are used. We first implemented our algorithm in C-language for simulation on various input images. As a result, we could obtain much enhanced images whose PSNR was improved by 4~8 dB compared to the commonly idealized approaches, and we also could remove the inclined red property which was an unique characteristics of the image sensor(CBN385B).Then we implemented it in hardware to overcome its problem of computational complexity which made it operate slow in software. The hardware was verified on Spartan-3E FPGA(Field Programable Gate Array) to give almost the same performance as software, but in much faster execution time. The total logic gate count is 45K, and it handles 25 image frmaes per second.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.307-310
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• 2005

본 논문은 CMOS 센서의 ISP 전처리 과정 후 최종 화면에 출력하기 위한 효과적인 이미지 스케일 블록을 저전력, 저비용에 맞은 독립된 하드웨어 장치로 설계 하고자 한다. 카메라 센서 이미지 결과를 디스플레이 장치(OSD(On Screen Display)에 맞는 화면의 크기는 CIF(352${\times}$288), QCIF(176${\times}$144) 출력 모드를 사용한다. 최근 DMB 휴대용 멀티미디어 데이터 전송 사이즈 포맷에서도 위와 같은 사이즈를 지원하고 있다. 일반적인 스케일 처리에서는 PC 그래픽 카드(Graphic Card)장치의 지원을 받아서 처리하는 경우가 많다. 또는 CPU의 연산을 통한 CPU 자원을 점유하여 이미지 스케일을 처리하였다. 휴대용 CMOS 센서용에 적합한 독립적으로 처리할 수 있는 이미지 스케일 기능을 하드웨어로 설계하여 효과적인 시스템 운용과 고속 이미지 스케일 처리가 가능한 하드웨어를 설계하는게 목적이다. 이를 구현 하기위해 기존 알고리즘과 제안한 알고리즘을 비교하여 최적화된 알고리즘 적용하여 VHDL설계언어를 이용한 하드웨어 설계 후, ModelSim 6.0a를 이용하여 데이터를 검증한다.

• The Optical Journal
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• s.131
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• pp.37-41
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• 2011

휴대전화에 카메라가 탑재된 지도 10년 이상이 지났다. 점차 고해상도화와 더불어 카메라로서 점점 실용적으로 진화하고 있다. 장기간 배터리 구동의 필요성에서 저소비전력은 중요과제이고, 종래의 CCD 이미지센서에서 CMOS센서로 거의 대체되었다고 할 수 있다. 기기의 소형화에 동반해 탑재되는 카메라모듈의 소형화에 대한 요구는 매우 강하다. 특히 박형화된 표시부와 함께 실장되는 inside 카메라의 저배화(低背化)는 급속히 진행됐다. 모듈의 높이를 낮게 하기 위해서는 광학렌즈의 광로장을 적게 하는 것이 요구되지만 고해상도 때문에 이미 지사이즈가 대형화하는 경향과 상반된다. 본고는 광기술컨텍트 2010년 10월호에서 발췌한 것으로서 이미지사이즈를 유지하면서 고해상도화를 실현하는 미세 셀에서 성능을 확보하는 기술과 카메라모듈을 소형화하는 기술에 대해서 개괄하였다.

• The Optical Journal
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• s.90
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• pp.60-65
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• 2004

현대의 정보통신 사회에 있어서 카메라는 여러 분야에 사용이 되고 있다. 카메라는 아날로그사진에서 피사체를 기록하기위한 필름을 사용하는데 이미지 센서는 빛을 변환하는 역할을 하는 필름대용품으로 사용되는 것이다. 이 이미지 센서는 전하결합소자(CCD : Charge Coupled Device)와 상보금속 산화물반도체(CMOS : Complementary Metal-Oxide-Semiconductor)가 대표적이다. 특히 디지털 카메라를 이용하여 과거의 카메

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.631-634
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• 2009

Recent advances in wireless communication, electronics, MEMS device, sensor and battery technology have made it possible to manufacture low-cost, low-power, multi-function tiny sensor nodes. A large number of tiny sensor nodes form sensor network through wireless communication. Sensor networks represent a significant improvement over traditional sensors, research on Zigbee wireless image transmission has been a topic in industrial and scientific fields. In this paper, we design a Zigbee wireless image sensor node and multimedia monitoring server system. It consists of embedded processor, memory, CMOS image sensor, image acquisition and processing unit, Zigbee RF module, power supply unit and remote monitoring server system. In the future, we will further improve our Zigbee wireless image sensor node and monitoring server system. Besides, energy-efficient Zigbee wireless image transmission protocol and interworking with mobile network will be our work focus.