• Journal of Bio-Environment Control
• /
• v.31 no.1
• /
• pp.14-21
• /
• 2022

Uniform scions and rootstocks should be produced to ensure grafting success. Light quality is an important environmental factor that regulates seedling growth. The effects of warm- and cool-white light emitting diode (LED) ratios on seedling growth were investigated. Scions and rootstocks of cucumber, tomato, and watermelon were grown in a closed transplant production system using LED as the sole lighting source. The LED treatments were W1C0 (only warm-white), W1C1 (warm-white: cool-white = 1:1), W3C1 (warm-white: cool-white = 3:1), and W5C2 (warm-white: cool-white = 5:2). The seedlings grown in W1C1 had the shortest hypocotyls, and the seedlings grown in W1C0 had the longest hypocotyls among the three tested vegetables. The hypocotyls of watermelon scions, watermelon rootstocks, and tomato rootstocks were shortest in W1C1, followed by those in W3C1, W5C2, and W1C0, but there was no significant difference between W3C1 and W5C2, which remained the same as the ratio of cool-white LEDs increased. In addition, tomato scions had the first and second longest hypocotyls in W1C0 and W3C1, respectively, and the shortest hypocotyls in W5C2 and W1C1, along with W5C2 and W1C1, although the difference was not significant. The stem diameter was highest in W1C0 except for tomato seedlings and rootstocks of watermelon. The shoot fresh weight of scions and rootstocks of cucumber and watermelon and the root fresh weight of cucumber scions were lowest in W1C1. These results indicated that different ratios of LED lighting sources had a strong effect on the hypocotyl elongation of seedlings.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.2
• /
• pp.284-288
• /
• 2015

The color temperature flexibility-typed Lighting Emitting Diode(LED) lighting control system proposed in this thesis employs Pulse Width Modulation(PWM) technique to control the brightness of LED lighting. The LED lighting used as a light source has 20W downlight composed of two types of LED chips: one is Warm White and the other is Cool white. One multi-sensor module consisting an infrared sensor, an illumination sensor, and a temperature sensor was made, to which Bluetooth wireless communication technique was applied to enable a smartphone application to control lighting brightness and identify the information collected from the sensor. CS-1000, a spectroradiometer, was used to measure LED dimming control and the changing values of a color temperature in eight steps. According to a test, it was found that it was possible to change a color temperature from 3187K of Warm White LED to 5600K of Cool White LED.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.1
• /
• pp.64-68
• /
• 2015

In this paper, LED lighting system is realized by using Bluetooth wireless communications and smartphones. A bluetooth module with a lighting control function is manufactured by miniaturizing a development board of TI company and the volume of LED dimming system as a whole is reduced. And a trial product is materialized by designing a hardware composed of the manufactured bluetooth module, LED down light equipped with degree warm white and cool white, and 2-channel LED driver; and LED dimming software. The materialized trial product is controled in terms of the brightness and color temperature of LED light source using an application of a smartphone. The experiment showed that the users can easily control the intensity of illumination of LED light source by using the scroll bar of the applications of smartphones. In addition, the color temperatures of both warm white and cool white can be controlled, and when the color temperature of the trial product using the manufactured bluetooth module is compared with that of a trial product of TI company, they show the same color temperatures.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.603-604
• /
• 2008

This paper implemented The LED illuminance control IP based on 8bit RISC Processor. 8bit RISC Processor designed hardware interrupts, an interface for serial communications, a timer system with compare-capture-reload resources and a watchdog timer. LED Array consists of Red, Green, Blue, White and Warm White. The illuminance control IP is used to LED Board control with 8bit data.

• Journal of the Korean Ceramic Society
• /
• v.49 no.1
• /
• pp.105-110
• /
• 2012

In this paper, a yellow phosphor $Sr_3SiO_5:Eu^{2+}$ that emits efficiently at the 450 nm excitation for warm white LED is studied. In addition, the effects of various flux $BaF_2$, $NH_4Cl$ on the emission spectra were investigated. The samples were synthesized through conventional solid state reaction under reducing atmosphere of 95% $N_2$-5% $H_2$ mixture at the high temperature. All phosphors showed a excitation band from 450 nm and broad band emission peaking at region of 580 nm. The optimal concentration of $BaF_2$ flux is 3 wt% for $Sr_3SiO_5$ with doping 0.05mol Eu phosphors fired in a reductive atmosphere. The phosphor showed highest emission peaking at 582 nm.

• Journal of the Korean Ceramic Society
• /
• v.52 no.4
• /
• pp.229-233
• /
• 2015

Currently, the majority of commercial white LEDs are phosphor converted LEDs made of a blue-emitting chip and YAG yellow phosphor dispersed in organic silicone. However, silicone in high-power devices results in long-term performance problems such as reacting with water, color transition, and shrinkage by heat. Additionally, yellow phosphor is not applicable to warm white LEDs that require a low CCT and high CRI. To solve these problems, mixing of green phosphor, red phosphor and glass, which are stable in high temperatures, is common a production method for high-power warm white LEDs. In this study, we fabricated conversion lenses with LUAG green phosphor, SCASN red phosphor and low-softening point glass for high-power warm white LEDs. Conversion lenses can be well controlled through the phosphor content and heat treatment temperature. Therefore, when the green phosphor content was increased, the CRI and luminance efficiency gradually intensified. Moreover, using high heat treatment temperatures, the fabricated conversion lenses had a high CRI and low luminance efficiency. Thus, the fabricated conversion lenses with green and red phosphor below 90 wt% and 10 wt% with a sintering temperature of $500^{\circ}C$ had the best optical properties. The measured values for the CCT, CRI and luminance efficiency were 3200 K, 80, and 85 lm/w.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.1343-1346
• /
• 2008

$KSrPO_4$ and $Sr_3(Al_2O_5)Cl_2$ phosphors doped with $Eu^{2+}$ emit a blue and orange-yellow luminescence under ultraviolet (UV) excitation at ~ 400 nm, respectivel, which can be used for making white light emitting diodes.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2009.10a
• /
• pp.197-200
• /
• 2009

주광의 색온도와 일치하는 실내 전반 조명용 60W급 LED 조명제품 개발하기 위하여 실내 주광에 적합한 LED를 선정하고, 색온도, 광색제어를 위한 구동회로 및 제어회로를 설계 제작 하였다. 그리고 1W급 Cool White, Warm White Package LED 총 168 EA를 적용하여 주광의 색온도와 일치하는 실내전반 조명용 LED 조명 System 을 개발하였다. 주광의 색온도와 일치하는 실내 전반용 LED 조명제품은 60W급 LED SMPS 구동회로 및 광색/색온도 제어회로 설계, 면발광을 위한 방열 설계 및 기구 구조 설계를 통하여 개발되었으며, 직접 시제품을 제작하고 그 성능을 측정하였다. 그 결과 회로 효율은 85% 이상, 색온도는 $3,000{\sim}7,000K$에서 실시간으로 제어 가능 하고, 원하는 색온도을 구현 할 수 있도록 하였으며, 발산각 또한 최대 광도의 1/2 기준으로 $100^{\circ}$ 이상을 만족시켰다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.2
• /
• pp.1-7
• /
• 2015

The Light Emitting Diode(LED) lighting control system proposed in this thesis is made up of a sensor module, a microcontroller, Bluetooth wireless communication, LED Driver, and LED downlight. The sensor module, comprised of an infrared sensor, an illumination sensor, and a temperature sensor, was designed to one Printed Circuit board(PCB). The system is able to identify the environment information collected by the sensor, and make it possible to control lighting automatically and manually through sensors. In addition, depending on users' conditions, a color temperature can be controlled. CS-1000, a spectroradiometer, was employed to measure the changing values of a color temperature in 8 steps. According to a test, it was found that it was possible to change a color temperature from 3187K of Warm White LED to 5598K of Cool White LED. The Bluetooth based wireless communication technique makes it possible to control more lighting devices than other wireless communication techniques does.

• Journal of Fisheries and Marine Sciences Education
• /
• v.29 no.2
• /
• pp.552-559
• /
• 2017

To assess the effect of LED lights on marine microalgae growth in the laboatory, Tetraselmis suecica, Chaetoceros simplex and Isochrysis galbana were cultured under $20{\pm}1^{\circ}C$, Walne's medium and aeration using 3.6 L glass vessels. The LED light sources were Blue, Red, Blue+Red, CoolWhite and WarmWhite. The experiments were conducted three times. The density of microalgae was shown as the counted number of cells per day, and the specific growth rate was calculated by using the density. The statistical analysis was performed by analysis of variance using the SPSS 20.0 program. T. suecica culture was the highest density under the Blue LED light source, so the light source was the most effective for the growth of this alga. C. simplex and I. galbana culture had the highest density under the Blue+Red LED light source, therefore this light source was the most effective for the growth of these algae. The result of analysis of variance showed significant between groups.