• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.6
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• pp.563-569
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• 2023

Micro light-emitting diodes (LEDs), with a chip size of 100 micrometers or less, have attracted significant attention in flexible displays, augmented reality/virtual reality (AR/VR), and bio-medical applications as next-generation light sources due to their outstanding electrical, optical, and mechanical performance. In the realm of bio-medical devices, it is crucial to transfer tiny micro LED chips onto desired flexible substrates with low precision errors, high speed, and high yield for practical applications on various parts of the human body, including someone's face and organs. This paper aims to introduce a fabrication process for flexible micro LED devices and propose micro LED transfer techniques for cosmetic and medical applications. Flexible micro LED technology holds promise for treating skin disorders, cancers, and neurological diseases.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.2
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• pp.121-127
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• 2022

Micro-LED is a light-emitting diode smaller than 100 ㎛ in size. It attracts much attention due to its superior performance, such as resolution, brightness, etc., and is considered for various applications like flexible display and VR/AR. Micro-LED display requires a mass transfer process to move micro-LED chips from a LED wafer to a target substrate. In this study, we proposed a vacuum chuck method as a mass transfer technique. The vacuum chuck was fabricated with MEMS technology and PDMS micro-mold process. The spin-coating approach using a dam structure successfully controlled the PDMS mold's thickness. The vacuum test using solder balls instead of micro-LED confirmed the vacuum chuck method as a mass transfer technique.

• Information Display
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• v.23 no.3
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• pp.22-29
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• 2022

• Journal of the Semiconductor & Display Technology
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• v.22 no.2
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• pp.1-5
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• 2023

In the past, display devices have undergone many changes, such as plasma TVs and LCDs, and have continued to develop. Recently, new display technologies, such as Organic Light Emitting Diode displays and Inorganic Light Emitting Diode displays, have been developed. Among them, Micro LED displays have the potential to improve performance more than LCDs and OLEDs, but a lot of effort and time are needed until the mass production technology (transfer and bonding) of Micro LED displays is developed. We have developed a new Micro LED display light source that can be produced using existing transfer and bonding process technologies to enable faster commercialization of Micro LED in the industry. This light source is TFT deposition on LED. TFT deposition on LED has the advantage of being able to produce displays using existing process technology, making early commercialization of display application products possible. In this study, we applied the Active Driving method to verify the performance of TFT deposition on LED as a display to determine its commercialization potential. Additionally, to facilitate faster application of Micro LED in the industry, we applied TFT deposition on LED to Optical Wireless Communication systems, which are widely used in application service areas such as safety/security and sensors, to verify its communication performance. The experimental results confirmed that TFT deposition on LED is not only capable of AM driving but can also be applied to OWC systems.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.1
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• pp.19-26
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• 2014

The purpose of this study was to investigate the human body effect according to micro bubble and LED lighting in half body bathing. This study was conducted on 6 elderly male and 7 female in 70's, and the subjects were classified into half body bathing with the micro bubble group (3 male, 4 female) and without the micro bubble group (3 male, 3 female) to proceed to the experiment. Experiments were performed 4 times by changing the LED lighting colors. As a result, parasympathetic nerves were activated than sympathetic nerves (micro bubble stimulation : 21.41%) and the temperature of the body were increased by $5.93^{\circ}C$ with micro bubble and red lighting stimulation. It is considered that this work will help to utilize the half body bathing system for the micro bubble and LED lighting.

• 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.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.220-221
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• 2008

본 연구에서는 빛을 확산시키기 위하여 LED(light emitting diode) 봉지층내에 마이크로 스피어를 형성하였다. 마이크로 스피어는 극성이 다른 이 종의 봉지재(실리콘, 에폭시)를 혼합하여 제조하였으며, 최적 첨가비율은 0.6wt% 이내였다. 광학현미경을 이용하여 측정한 결과, 마이크로 스피어의 직경은 $4{\mu}m$ 내외였으며, 마이크로 스피어는 서로 들러붙거나 침전하지 않았다. LED의 효율은 봉지재의 첨가비율이 증가할수록 감소하였으며, 0.6wt% 첨가하였을 때 약 10% 이내의 효율 감소를 보였다. 지향각은 봉지재 첨가비율을 0${\sim}$0.6wt%로 변화시키면 50도에서 110도까지 증가하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.191-198
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• 2015

The purpose of this study is to develope a current variation control system appropriate to the various LED(Light Emitting Diode) lamps using current control system equipped with microcontroller based voltage regulator of power driving circuit. For this, we will suggest a stable control system of current variation to enable a stable power-supply and current-control, consisting of circuit to minimize the affects on the LED forward voltage using variable resistance and compensating resistance. The method of constant current circuit and energy savings using microcontroller based voltage regulator suggested in this study can be applied to various a big capacity LED lamp to minimize the unnecessay heat generation and to control resistace delicately. Ultimately, we expect the results of this study will upgrade the reliability of LED lamp by supplying the current stably.

• Journal of Satellite, Information and Communications
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• v.7 no.2
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• pp.54-58
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• 2012

In this paper, we implemented total monitoring system in which LED light turned on only when user detected and LED light turned out only when user disappeared. This system is composed of two modules, one is HW board based on Micro Controller and the other is SW control system based on Web server. Micro controller board is based on ATMega2560 chip which is connected with Infra Red and Ultra sonic sensors. Web based monitoring system was designed can be used in smart device. The validity of this monitoring system was proved by integration test of two modules.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1726-1727
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• 2011

본 연구는 RGB LED 패키지의 특성에 대한 전기적 분석을 통해 LED 조명 설계에 있어 보다 효율적인 설계를 구현하고자 하였으며 마이크로 컨트롤러를 이용한 구동회로 제어와 적외선 센서를 이용한 원격제어를 통해 폭넓은 색 조절을 위한 LED에 최적화 된 brightness 및 chroma 제어 기술을 실현하고자 설계 및 분석을 하였다. 그 결과 색온도에 대한 제어의 경우 총 12가지의 mode를 바탕으로 색상을 제어 하였으며 LED 패키지의 전류변화에 따른 광 출력을 고려하여 최적화 된 brightness 및 색온도에 대한 제어가 가능하였다.