• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.14-25
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• 2011

Full-Color LED lighting system requires efficient control of the lighting color in order to easily achieve various color effects. In this paper, we present not only a portable color scanner using color sensors which can control lighting color directly from detected color but also methods to convert detected color to a complementary color, similar colors and so on. In addition, we propose a compensation method for measured sensor color to reduce measurement errors more than 50[%] in detected color. The developed color scanner is applied to control full-color LED ceiling light for emotional lighting.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.1118-1121
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• 2010

With the advent of cell phone digital cameras, and sophisticated photo editing software, digital images can be easily manipulated and altered. Although good forgeries may leave no visual clues of having been tampered with, they may, nevertheless, alter the underlying statistics of an image. Most digital camera equipped in cell phones employ a single image sensor in conjunction with a color filter array (CFA), and then interpolates the missing color samples to obtain a three channel color image. This interpolation introduces specific correlations which are likely to be destroyed when tampering with an image. We quantify the specific correlations introduced by CFA interpolation, and describe how these correlations, or lack thereof, can be automatically detected in any portion of an image. We show the efficacy of this approach in revealing traces of digital tampering in lossless and lossy compressed color images interpolated with several different CFA algorithms in test cell phones.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.161-167
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• 2012

Portable devices such as smartphones with built-in wireless LAN to the prevalence of anyone using. But the wireless Internet connection and positioning services are limited to high-quality wireless service, they may not be available. Thus, wireless LAN infrared sensor in the same way as with angry alternative way wireless capabilities of the application automatically identify the location of the Sensor application as an alternative method is proposed. Thus, wireless LAN, such as infrared sensors and other alternzative methods of wireless features in a way where the application can recognize and automatically recognize the sensor application as an alternative method is proposed. Sensor is signals between wireless LAN and access points using the sensitivity, WLAN antenna with omni-directional signal output operation of the sensor is assumed to be recognize this by putting a direction to obtain through the proposed algorithm, Sensors such as photo-coupler without direct recognition sensor, wireless LAN and access points, the same function as the connection between the sensitivity to perform its function was to utilizing.

• Journal of Sensor Science and Technology
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• v.18 no.6
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• pp.467-474
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• 2009

In this study, we describe the feasibility of developing a fiber-optic temperature sensor using a thermochromic material such as 2,4,5-triphenylimidazole or also called Lophine. A sensor-tip is fabricated by mixing of a Lophine powder, which has a non-toxic and hydrophobic characteristics, and an epoxy resin. The temperature change in the sensor-tip gives rise to a change in the optical absorbance of the Lophine, and the transmittance of a light through the Lophine is also changed. We have measured the intensities of modulated lights due to the change of optical absorbance of the Lophine by using of a photo-multiplier tube(PMT). The relationships between the temperatures and the output voltages of PMT are determined to measure the temperature of water. The measurable temperature range of the fiber-optic sensor is from 5 to $30^{\circ}C$.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.2
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• pp.155-161
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• 2016

This paper proposes a novel fabrication method for a capacitive type micro-accelerometer with uniform nano-gap using photo-assisted electro-chemical etching. The sensitivity of the accelerometer should be improved while the electrodes between the inertial mass and the sensing comb should be narrowed. In this paper the nano-gap trench structure is fabricated using the photo-assisted electrochemical etching method. The sensor was designed and analysed using ANSYS simulator. The characteristics of the etching were observed according to the dc bias, the light intensity, the composition of the solution, the temperature of the solution, and the pattern pitch variation. The optimum etching conditions were dc bias of 2V, Blue LED of 20mA, 49wt% HF:DMF:D.I.Water=1:20:10, the pattern pitch of $20{\mu}m$. Uniform trench structure with width of 344nm and depth of $11.627{\mu}m$ are formed using the optimum condition.

• Korean Journal of Food Science and Technology
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• v.25 no.4
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• pp.391-394
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• 1993

For the automation of Tackjoo fermentation, a sensor measurable gas production during brewing and a controller were built. The performance tests were carried out at 10 litter Tackjoo fermentor, The sensor was consisted of a transparent acryl cell for bubble formation and photo-interrupter for the detection of bubbles of 0.018ml size. The fermentation controller was fabricated with a single chip microcomputer (MC68705R3) and provided with both the monitoring module of temperature measurement and the valve controling device for the cooling water circulation in coil type heat exchanger. The operation programs were developed and systemized in ROM. With this computer system, the gas production amount and rate were acquired during the Tackjoo fermentation. The fermentation curve based on the gas production rate showed a good agreement with that of alcohol concentration. The maximum rate of gas production was found after 24 hr at $30^{\circ}C$. The correlation equation between the gas production and alcohol concentration was established and used as the control algorithm of the fermentation.

• Journal of Sensor Science and Technology
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• v.12 no.4
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• pp.191-197
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• 2003

Due to explosive increase of internet usage, broadband data transmission using optical fibers is broadly used. In order to decrease distortion during long distance transmission, the optical signal need to be restored, typically, by converting the optical signal into the electrical signal. The optical signal is converted into the electrical signal using a photo-diode, and then a clock-and-recovery (CDR) circuit is used to recover the clock and retime the data. In this study, a clock-and-data recovery circuit has been designed using a standard 1.8 V $0.18\;{\mu}m$ CMOS process. With this CDR circuit, the improved phase detector and charge pump have been utilized. Also, by using a ring oscillator, the CDR circuit can recover clock and data from broadband multi-rate data ranging between 750 Mb/s and 2.85 Gb/s.

• 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.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.4
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• pp.388-396
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• 2011

Sun tracking system is the most important subsystem in parabolic dish type solar thermal power plant, since it determines the amount of thermal energy to be collected, thus affects the efficiency of solar thermal power plant most significantly. Various types of sun tracking systems are currently used. Among them, use of photo sensors to located the sun(which is called sensor type) and use of astronomical algorithm to compute the sun position(which is called program type) are two of the mostly used methods. Recently some uses CCD sensor, like CCD camera, which is called image processing type sun tracking system. This work is concerned with the analysis of sun tracking performance of various types of sun tracking systems currently used in the parabolic dish type solar thermal power plant. We first developed a sun tracking error measurement system. Then, we evaluate the performance of five different types of sun tracking systems, sensor type, program type, hybrid type(use of sensor and computed sun position simultaneously), tracking error compensated program type and image processing type. Experimentally obtained data shows that the tracking error compensated program type sun tracking system is very effective and could provide a good sun tracking performance. Also the data obtained shows that the performance of sensor type sun tracking system is being affected by the cloud significantly, while the performance of a program type sun tracking system is being affected by the sun tracking system's mechanical and installation errors very much. Finally image processing type sun tracking system can provide accurate sun tracking performance, but costs more and requires more computational time.

• Journal of the Korea Society of Computer and Information
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• v.19 no.2
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• pp.101-107
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• 2014

This study is proposed the novel PPG sensor device and the signal processing method to replace the acceleration sensor that is used to reject motion artifacts contained in photoplethysmography(PPG). The proposed method is to reject motion artifacts by an adaptive filter based on the estimated motion artifact by using a blue LED light. To evaluate the performance of the proposed method experimentally, We did design a novel sensor consisted of blue/red LEDs and photo-sensor and implemented, and then rejected the motion artifacts by using an adaptive filter and the implemented sensor. In the results of the experiments, it is shown that the proposed sensor device and signal processing can reconstruct the PPG signal despite the occurrence of motion artifacts, and also that the SNR was 4.5 times of moving average filter. According to the experimental results, the proposed method can be applied to design a low-cost device.