• Journal of IKEEE
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• v.22 no.3
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• pp.742-746
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• 2018

In this paper, we implemented a VLC(Visible Light Communication) system capable of transmitting/receiving data on a 30MHz clock based on On/Off keying modulation/demodulation. The data rate of the implemented system can be verified by functional verification of VLC channel composed of LED/photodiode driver and VLC transmitting/receiving signal of Tx/Rx platform. But, In the experimental results with the VLC transmitting/receiving for combined module, the maximum transmission rate was measured at 15 MHz. Therefore, we describe the problems that can occur when implement the VLC system using the LED module with output power of 15W or more and propose ways to improve it.

• Korean Journal of Optics and Photonics
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• v.32 no.4
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• pp.163-171
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• 2021

Conventional white light-emitting diodes (LEDs) for lighting applications consist of blue LEDs and yellow phosphors, the spectrum of which lacks deep red. To improve the color-rendering characteristics of white LEDs, a red quantum-dot film was applied to the diffuser plate of LED lighting. The mean free paths of the quantum dots and the concentration of the TiO₂ particles in the diffuser plate were adjusted to optimize the optical structure of the lighting. The color-rendering index (CRI) was greater than 90 for most conditions, which demonstrates that adoption of the red quantum-dot film is an effective way for improving the color-rendering properties of conventional white LEDs. The angular dispersion of color coordinates could be removed by utilizing the optical cavity formed between the diffuser plate and the reflector on the bottom of the lighting, where multiple passages of the light through the quantum-dot film reduced the differences in optical path length depending on the viewing angle.

• Journal of Industrial Convergence
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• v.17 no.4
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• pp.125-129
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• 2019

With the growing number of people using bicycle, the number of bicycle accidents also has been increasing. It is said that bicycle accident can be reduced up to 11%~44% when riding a bicycle if LED light is used. The headlight of the bicycle makes exposure effect to the opposite side of bike rider while taillight makes exposure effect to the rear bike rider for improving safety. Bicycle safety device capable of displaying a change of direction by LED is implemented in this study in response to control button signal. This signal makes LED light which is installed in pedal and wheel of bicycle as a module type emitting or flickering during the fixed hour. Bicycle auxiliary device in pedal which is able to improve safety using LED when bikers are riding a bike at night is developed in this study. Bicycle safety device applying wireless communication technology will be expected alternative technology in the future to solve a social problem such as energy, environment, and safety.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.5
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• pp.315-323
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• 2021

Tunnel is the most energy-consuming structure in road due to the characteristic of using artificial lighting during day and night. Therefore, tunnel lights are being replaced by LED lamp that have advantages with respect to low power consumption. The best use of social overhead capital can be expected by considering the life cycle cost, because to tunnel structures are accompanied by a series of medium-to-long-term and continuous processes of replacing auxiliary facilities. In this study, the saving effect by LCC analysis was quantitatively analyzed by replacing tunnel light sources from high-pressure sodium lamps to LED lamps. The effect of reducing the replacement cycle by increasing the life of the lamps and the resulting maintenance cost is very significant, on replacing tunnel lighting light sources with LED lamp.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.4
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• pp.211-220
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• 2021

Low-pressure sodium lamps, high-pressure sodium lamps, and fluorescent lamps are mainly used for tunnel lighting in Rep. of Korea, which accounts for the highest percentage in the tunnel maintenance costs. Therefore, tunnel lights are being replaced by LED lamp that have advantages with respect to low power consumption and sustainability. To analyze the effect of replacement high pressure sodium lamp with LED lamp, illumination and monthly power usage per year have been investigated for 10 tunnels. The usage of LED lamp results in illumination improvement from 27.9% to 490% and power saving around average 47.1%.

• Journal of Industrial Technology
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• v.30 no.A
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• pp.25-29
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• 2010

In this paper, we implement a multi-touch system using FIDR. The implementation consists of hardware manufacture and development of image processing system. In the hardware system, touch screen, infrared LED placements and infrared camera are made. The image processing procedure is to extract each pointer's coordinates from image data and includes binary-coding, noise-elimination, labeling and calculation of mass center. From the implementation, we are able to make a multi-touch system with considerably lower cost than the existing ones.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.5
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• pp.233-240
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• 2012

White LEDs (light-emitting diodes) are promising new-generation light sources which can replace conventional lamps due to their high reliability, low energy consumption and eco-friendly effects. This paper briefly reviews recent progress of oxy/nitride host phosphor and quantum dot materials with broad excitation band characteristics for phosphor-converted white LEDs. Among oxy/nitride host materials, $M_2Si_5N_8$ : $Eu^{2+}$, $MAlSiN_3$ : $Eu^{2+}$ M-SiON (M = Ca, Sr, Ba), ${\alpha}/{\beta}$-SiAlON : $Eu^{2+}$ are excellent phosphors for white LED using blue-emitting chip. They have very broad excitation bands in the range of 440~460 nm and exhibit emission from green to red. In this paper, In this review we focus on recent developments in the crystal structure, luminescence and applications of the oxy/nitride phosphors for white LEDs. In addition, the application prospects and current trends of research and development of quantum dot phosphors are also discussed.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.74-81
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• 1999

The integrated chip of optical micro-encoder was fabricated and the feasibility as displacement measurement device was confirmed. The geometry of micro-encoder was designed to utilize the optical interference effect on the second order of diffracted beams. The hybrid-type micro-encoder consisted with light emitting diode, photodiode, polyimide wave-guide and micro-lens provides stable micro-encoding results for high speed displacements. The measurement shows the resolution of displacement of 1.00 +/- 0.02 ${\mu}m$ for the grating with scale pitch of 2.0${\mu}m$.

• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.423-428
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• 2007

본 연구는 기존의 프레젠터의 단순한 포인터 및 클릭 기능을 넘어선 다기능 제스처 인식 포인터의 구현이 주 목적이다. 주된 연구 내용으로는 적외선 발광 다이오드에서 나오는 빛을 인지하여 포인터의 궤적 인식을 하는 기술과 이를 응용한 어플리케이션의 개발에 있다. 본 하드웨어에는 기본적인 마우스 클릭 기능 외에도 적외선 발광 다이오드를 탑재하여 PC와 연결된 카메라가 이를 인지하도록 한다. 장점으로는 카메라가 항상 PC와 가까이 있을 필요가 없으므로 어느 장소이든 관계없이 적외선 투과 필터가 장착된 카메라 하나만 설치할 수 있는 곳이면 구현이 가능하며 적외선을 이용하므로 가시광선의 영향을 적게 받아 효율적으로 영상 처리를 할 수 있다는 데에 있다. 제스처 인식을 통하여 수많은 여러 가지 기능을 실행할 수 있으며, 보다 사용자와 인터랙티브한 작업이 가능해진다. 구현된 하드웨어와 소프트웨어 시스템은 프레젠테이션 및 게임 컨트롤에 사용되었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.15-16
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• 2012

General lighting will be replaced into LED due to the high efficiency, low power consumption, long life than conventional light, moreover, since it is a basically semiconductor device that can convert the electric energy to visible light at a very high speed, using these characteristics can be performed communication modulation via the high-speed ON-OFF switching. Recently, visible light communication (VLC: Visible Light Communication) technology is received attention and there have been many researches. This paper is implemented media signal transmission by combining LED with VLC, a transmitter used the LED light-emitting device and receiver used an infrared sensor. In order to increase the efficiency of the communication system to improve the existing LED visible light communication driver of power conversion efficiency and thermal issues that is applied to the visible light communication in order to improve the speed of transmission media to research a new way of LED driver.