• Journal of the Microelectronics and Packaging Society
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• v.24 no.2
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• pp.55-59
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• 2017

An optical method to inspect the 3-D shape of surface of Micro BGA is proposed, where spatially arranged LED light sources and specular reflection are considered. The reflected image captured by a vision system was analyzed to calculate the relative displacements of LED's in the image. Also, the statistics for all BGA's contained in a captured image are used together to find out the criteria for the detection of existing defects, and the usefulness of the proposed method is shown via experiments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1275-1282
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• 2012

This paper proposes the 16-channel LED Driver IC for Full color LED display system. The proposed LED driver IC in this paper can draw current independent of temperature and supply voltage in each channel. Current flow in the channel is configurable via an external resistor. LED brightness is adjusted by 12-Bit PWM(Pulse Width Modulation) and 8-Bit DC(Dot Correction). A real-time monitoring of IC temperature ($130^{\circ}C/150^{\circ}C$) and LED status (open/short) is provided by LED driver IC and the user can receive warning and get information on problems. A 16-channel LED driver IC is produced using 0.35 um BCD process and the size is $2.5mm{\times}2.5mm$. In this paper, channel current characteristic and channel current control function were measured in order to verify am embodied 16-channel LED driver IC by producing a single IC test board.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.1-7
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• 2020

In recent years, as LED display systems are actively spread, study on effective control methods for an LED driver for driving the systems has been in progress. The most representative among them is the uniform brightness control method for the LED driver channel. In this paper, we propose an LED driver IC for BLU with current compensation and system protection functions to minimize channel luminance deviation. It is designed for current accuracy within ±3% between channels and a channel current of 150 mA. In order to satisfy the design specifications, the channel amplifier offset was canceled out by a chopping operation using a channel-driving PWM signal. Also, a pre-charge function was implemented to minimize the fast operation speed and luminance deviation between channels. LED error (open, short), switch TR short detection, and operating temperature protection circuits were designed to protect the IC and BLU systems. The proposed IC was fabricated using a Magnachip 0.35-um CMOS process and verified using Cadence and Synopsys' Design Tool. The fabricated LED driver IC has current accuracy within ±1.5% between channels and 150-mA channel output characteristics. The error detection circuits were verified by a test board.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.835-836
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• 2011

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.387-390
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• 2014

In this paper, we propose to study on the application of the alarm algorithm to the platform of portable radiation detection device based on Coretex-A9 to ensure the safety of user. The analog board transforms sensor's signal and the platform based on Cortex-A9 outputs the results. The radiation detection's alarm is realized to LED and Buzzer to ensure safety of user.

• Journal of IKEEE
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• v.23 no.2
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• pp.571-579
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• 2019

Visible light communication (VLC) performs illumination and communication simultaneously, thus it is important to prevent the flicker due to the optical power variation during data transmission and at the same time to have dimming control capability. In this paper, we used Manchester code for flicker-prevention and dimming control. In the transmitter, the duty factor of the Manchester code was used for controlling the LED illumination. In the receiver, the edge-spike signals of an RC-high pass filter were used for recovering the Manchester code while preventing the adjacent noise light. In experiments, the LED light was kept flicker-free and the average optical power was controlled in the range of 8~68 % of the continuous wave (CW) LED light by changing the duty factor of the Manchester code.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.823-826
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• 2016

This paper proposes a method for detecting automatically a smartphone camera in order to put a security stickers and detecting security sickers to recognize whether the removable security sticker or not. The method reduce the time that a person put a security stickers and check the stickers whether the removable stickers at rush hour. It is significantly low to detect rate if the image quality is poor low by LED light flickering phenomenon at the time of the camera detection of the smartphone. Therefor, in this paper, it implement the method that detecting camera to inspect frequently degree after applying the adaptive threshold. Further, in order to recognize whether the removable security sticker or not implement the sticker region detection method using a color filter. The proposed method could increase detecting ratio than earlier methods with LED light flickering phenomenon. In addition, it was also high security sticker detection ratio.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.197-203
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• 2015

Nuclear power plant has increased continuously for power production in all over the world and the interest about nuclear accident and the dismantling of aging nuclear power plant has been a growing. The leaked radioactive source that is generated by radiation accidents must detect and remove to minimized the damage as soon as possible. Gamma-ray detection system that have been developed until now cannot provide the precise position of radioactive sources because they detect and imaging the position of radiation sources in just two dimensions. In this paper, stereo gamma ray detection system has developed and the algorithm for calculation of the distance has implemented to be able to measure the distribution of the leakage gamma ray source for the system. Stereo camera calibration for distance detection was conducted with the correction pattern and LED light and we carried out performance test of the system for the LED light source and a gamma ray source. In both experiments the results of the performance test, it was confirmed to have a 5% error. The results of this paper is used as a material for the development of gamma-ray imaging device.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.273-274
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• 2018

Recently, many countries around the world are investing heavily in green industries based on green IT technology. The key industry in the green industry is LED. If we replace traditional lighting, we can save a lot of socioeconomic costs. Because it is energy efficient. However, the research and development on maintenance and management are still insignificant about LED lighting. Therefore, after the failure, the post-treatment is delayed and often occurs. In order to solve these problems, it is planned to detect the failure of the LED lighting and to establish a monitoring system that can monitor the situation in real time on the computer or mobile phone of the remote manager using the latest IoT network technology.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.2
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• pp.125-130
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• 2016

In this paper, various heat dissipation designs for a rail anchoring failure detection module were investigated by a thermal flow analysis. For the detection module with the heat dissipation design on the overall housing surface, an average temperature inside the module was lowered by $25^{\circ}C$ when compared to no heat dissipation design. In addition, an internal heat-flow blocking layer and an heat conduction layer inserted between the LED module and housing case were effective in reducing the temperature in the rail anchoring failure detection, which has a limited space for installation and little air flow. Especially, the temperature near LED module decreased below $55^{\circ}C$ when the optimal heat dissipation design was applied.