• Journal of Bio-Environment Control
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• v.19 no.3
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• pp.140-146
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• 2010

This experiment was conducted to find the day and night temperature combination and the light-emitting diodes (LEDs) on the most effective globe coloration and growth of Chamecereus silvestrii f. variegata 'Hee-Mang'. The $L^*$value, $a^*$value and $b^*$value were all significant difference in the yellow globe color expression in the day and night temperature combination. Especially, the bright yellow color and visual value were the highest in the temperature combination, the day temperature of $20^{\circ}C$ and night temperature of $20^{\circ}C$. Globe color quality was lowered from the day temperature of $25^{\circ}C$ and night temperatures of $5^{\circ}C$ and $10^{\circ}C$ combination. In light-emitting diodes (LEDs) treatments, $a^*$value and $b^*$value are significant difference. A unique beautiful yellow coloration and globe quality were maintained the $a^*$value of +5.23, $b^*$value of +39.9 in a red LED. The optimum temperature range and light-emitting diodes (LEDs) on the globe color expression were the most effective the day temperature of 200e and night temperature of $20^{\circ}C$ and a red LED. In addition, the outer globe color quality of Chamecereus silvestrii f. variegata cultivation, rather than the light environment improvement is better in a proper temperature environment to keep. Especially, a unique globe color expression of yellow lines was most effective in a red LED.

• Electronics and Telecommunications Trends
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• v.30 no.6
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• pp.42-49
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• 2015

질화물 반도체 기반 가시광 청색 Light Emitting Diode(LED) 기술은 디스플레이의 Back Light Unit(BLU)뿐 아니라 일반 조명에 활용되며 우리 실생활에서 매우 밀접하게 사용하고 있다. 가시광보다 짧은 파장을 가지는 자외선 LED의 경우 경화기 및 위폐감지기에 기존의 유해 가스를 사용하는 자외선 램프를 대체하고 있다. 자외선 광원의 또 다른 거대 시장으로 살균 및 정화, 의료 및 바이오 응용 시장에서 자외선 램프를 대체할 수 있는 자외선 LED 기술이 활발히 발전하고 있다. 본고에서는 이들 자외선광원 시장동향과 국내외 자외선 LED의 기술동향을 파악하므로 앞으로 연구개발의 방향을 모색하고자 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.43-44
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• 2012

본 논문에서는 도로조명용 LED 이차광학계의 제조공정에서 발행하는 형상오차를 설계에 반영하여 제작 후 형상 정밀도를 높여 궁극적으로 도로조명의 조명율을 향상시키는 방법을 제시하였다. 이를 통하여 동일한 에너지를 소모로도 더 높은 광밀도를 가질수 있는 LED2 차렌즈의 제조방법을 제시하였다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.141-144
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• 2009

LED Lightings market remains highly fragmented, encompassing many niche applications. Architectural lighting is the largest and many applications are for colored (R, G, B) light. Hundreds of companies worldwide are participating at the luminaire or fixture level. Standard setting is on a fast track. The larger LED lightings market scale, the more important standardization of performance evaluation techniques to clearly prescribe the product specification.

• Journal of Plant Biotechnology
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• v.35 no.3
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• pp.215-221
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• 2008

Effects of light generated by LEDs on shoot growth and rooting of Tsuru-rindo(Tripterospermum japonicum) were evaluated. Apical shoots(one or two node with 3-4 leaves) were cultured on MS basal medium with 3% sucrose and maintained for four weeks under five different light qualities: fluorescent lamp(F), 100% red LED(R), 70% red LED+30% blue LED(R7B3), 50% red LED+50% blue(R5B5), or 100% blue LED(B). Rooting was promoted by both red light and fluorescent lamp, and the effect was further promoted under the ventilation. Red light enhanced shoot node elongation, whereas blue light appeared to suppress it. Growth of shoots and leaves were enhanced under the ventilation irrespective of the different light qualities. Under the ventilated condition, total fresh weight of plants was highest in R7B3 LED as 257.7 mg per plant. Dry matters, which are used for index of plant growth, were lowest under red light, whereas it was highest under blue light. The dry matter was inclined to getting higher by ascending the ratio of blue light and red light. Total chlorophyll content was highest in both R7B3 LED and R5B5 LED under ventilation as 29.5 and 31.2, respectively. Above results suggest that light quality optimization could be an important factor to foster in vitro growth of the species. Ventilation treatment appeared to be another important factor to induce normal shoot growth and rooting.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.6
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• pp.476-481
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• 2014

In this paper, we design the pre-equalizer of transmitter circuit in order to enhancement modulation bandwidth of white LED which is light source of VLC (Visible Light Communication). Also, we eliminate yellow light component by optical filtering which mitigate frequency response of white LED. Power loss by optical filtering is overcome by using convex lens. By applying proposed system, 3 dB bandwidth deciding modulation bandwidth of white LED increases from 3 MHz to more than 25 MHz and the transmission distance increases by optical design which secure additional signal power. We optically modulate NRZ-OOK signal to LED and receive light signal using APD. We analyze received data using CSA and RFSA. As a result, we experimently demonstrate the possibility that transmits NRZ-OOK signal up to 30 Mbps in 4.5 m, 50 Mbps in 1.5 m through the pre-equalizer and optical design.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4B
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• pp.391-398
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• 2011

In this paper, we propose a MAC protocol for visible light wireless LAN using LED light. The proposed MAC protocol has a function of automatic direction optimization for LED transceiver. There is periodical time slot for broadcasting and registration in the proposed MAC protocol. We used polling method for data transfer in the protocol since visible light is hard to detect carrier and collision by other mobile stations; thus we cannot use CSMA/CD method in visible light LAN. We also amended the MAC frame of IEEE 802.11 to propose a revised version for visible light wireless LAN using LED light. We investigate the performance of the proposed MAC protocol. When the bit rate of physical layer is 100 Mb/s, the net data throughput using the proposed MAC protocol is estimated to 94.386 Mb/s.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.9
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• pp.15-22
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• 2013

A new LED lamp driving technology with a charge pump instead of a conventional DC-DC converter is proposed. The proposed driving technology is used to control the LED lamp with digital dimming. The power loss in the zener diodes is reduced because the charging process of the capacitors is selectively controlled according to the digital control signal. From the experimental results, when dimming four LED lamps simultaneously, the average driving circuit efficiency of 89% is obtained, regardless of the dimming level. White light with color temperature over a range of 2800~7200K was produced by dimming control of red, green, blue and amber LED lamps with the proposed driving circuit. The characteristics of the driving circuits can be changed depending on the characteristics of the R, G, B, and A LED lamps. The efficiency of the driving circuits up to a maximum 89% can also be obtained depending on the combination of LED lamps. The driving technology with digital dimming control for LED lamps proposed in this paper would be effective for obtaining high efficiency in LED driving circuits and remote control of LED lamps using digital communications.

• Journal of Plant Biotechnology
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• v.48 no.2
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• pp.77-85
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• 2021

Hydroponic cultivation, in which crops are grown without soil and are unaffected by the weather, has many advantages over conventional soil cultivation. The crop's growth can be further accelerated by using nutrient solution in place of water. This study investigated the growth and physicochemical properties of hydroponic barley sprouts under various nutrient solution and artificial light treatments. The shoot, root, and total plant length increased over time, with the fastest growth occurring in the nutrient solution and light-emitting diode (LED) treatments. Fresh and dry plant weights were higher in the fluorescent lamp treatment than in the LED treatment. Barley sprout powder color differed slightly by treatment, with the Hunters L value ranging from 50.79 to 53.77; Hunters a value from -6.70 to -4.42; and Hunters b value from 13.35 to 14.76. The Hunters L and Hunters b values were highest in the LED treatment, whereas the Hunters a value was relatively highest in the fluorescent lamp treatment. The total phenol content was higher in the control than in the nutrient solution treatment; however, the total flavonoid content showed the opposite pattern to that of total phenol content, being highest in plants that were grown in nutrient solution. The Trolox equivalent antioxidant capacity (TEAC) was higher in the control group than in the nutrient solution group. The ferric ion reducing antioxidant power (FRAP) was higher in the fluorescent treatment group than in the LED treatment group. The total amino acid composition ranged from 106.82 to 122.63 mg/g dry powder, with the essential amino acid composition ranging from 47.01 to 56.19 mg/g, and non-essential amino acid composition from 67.86 to 77.66 mg/g. The most frequently detected compositional amino acid was aspartic acid, followed by glutamic acid, alanine, leucine, and valine.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.71-76
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• 2007

본 논문에서는 고 연색성의 실시간으로 색온도 제어 가능한 승강기용 조명제품 개발을 위하여 제품에 사용될 LED Package를 제작하고 고연색성 실현을 위한 색온도 제어 기초실험을 행하였다. 그리고 20W 급의 LED 광원모듈 구동회로와 색온도 제어를 위한 제어회로를 설계하였다. 또한 음영 제거 및 글레어 차단, 효과적인 광색혼합을 위하여 확산배광을 달성하기 위한 R, G, B, A, W LED의 최적 배치 및 렌즈의 광학설계를 수행하였고 LED에서 발생하는 열을 효과적으로 발산하여 LED 조명모듈의 온도를 낮추기 위한 방열설계를 실시하였다.