• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.8
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• pp.32-39
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• 2014

In general, non-directional LED lamps including high transmittance cover are more advantageous than directional LED lamps, which are efficient enough to improve luminous efficacy and obtain certification, allowing wide manufacture, sale, and distribution. Although KS C 7651(Self-ballasted LED lamps-Safety and performance requirements) was revised in July 2013, however, many companies are having a lot of difficulties in keeping the certification and product development for the lack of the photometric analysis for non-directional LED lamps. In this paper, through the measurement of the angular distribution of luminous flux of incandescent lamp and non-directional LED lamps, we examined the reasonability of non-directional LED lamps' standards as suggested in KS C 7651. According to the results, even if non-directional LED lamps satisfy KS C 7651, when compared to an incandescent lamp, they showed less diffusive than the incandescent lamp and the distribution of the luminous flux depending on the angle fluctuated greatly even among LED lamps. Judging by the result, the current standard of the non-directional LED lamps, KS C 7651, has been comprehended that the angular distribution of the luminous flux needs to be presented after being much more thoroughly standardized.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.2
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• pp.235-240
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• 2010

In order to substitute incandescent lamps, a power supply device for 7W class LED lamps which are environmentally friendly and energy saving is designed LED lamps consist of a multitude of chip LED connected in parallel and series. 11ms it is necessary to supply LED lamps with DC voltage and current. However, when LED lamps are in use, they are connected directly to AC 220V. This is why we need to have AC/DC, DC/DC power converters including a control system of voltage and current. For this, a transformerless and simple LED lamp driver is designed 조ich can control the current and output voltage for LED string of LED lamp.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.10
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• pp.1-6
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• 2015

As lamps using LEDs are developed actively, also there have been large request for LED lamps that can replace traditional lamps like fluorescent lamps and metal halide lamps. But so far there are no proper standards that manufacturer can use and test their lamps. As a result of this, manufacturers are not only unable to develop LED lamps but also sell it even though they have technology. In this study, It is proposed that proper test method by investigating compatibility between all-type control gear and LED lamps by analyzing control gear for fluorescent lamp such as magnetic or electronic ballast that is currently used in the market.

• 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.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.5
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• pp.615-622
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• 2015

As the development of high efficiency and high flux density LEDs, the trend of illumination lamp industry transfers from conventional-lamps to the LED-lamps. For energy efficiencies, LED lamps are superior to the conventional lamps, but they have heat problems. Especially, the heat problems are severe for the high luminance lamps. They degrade the soldering point of the metal PCB, and shorten the life cycle of LEDs. So, the solution of the heat sinking is very important to develop high luminance LED lamps. This study suggested a new method to solve the heat problems for high luminance LED lamps, and developed a LED lamp which has 1200W power. In this study, a water jacket is installed to the LED lamp, and the cooing water is circulated by a water pump.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.2
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• pp.24-31
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• 2011

The purpose of this study is to find an efficient way using dimmable LED lamps to describe specific target illuminance and color temperature. This study used 14 dimmable LED lamps as same or different color temperature. The method of study is to measure of electric power consumption using different color temperature of dimmable LED lamps that were combination of two or three dimmable LED lamps by simultaneously dimming. Through this method, the electric power consumption was compared with all combinations of the illuminance and color temperature.

• Asia Pacific Journal of Business Review
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• v.2 no.2
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• pp.1-15
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• 2018

The purpose of this paper is to find out the factors responsible for purchase of LED (light-emitting-diodes) bulbs & tubes among Indian consumers and how much they are ready to replace their existing lighting system with LED fittings. A multiple regression model has been employed to investigate the factors affecting the buying decision of LED lamps in place of CFL and incandescent lamps. Eleven motives for adopting LED lamps has been identified viz. price, quality, energy saving, durability, brand, promotion, CSR, & environmental consciousness. In addition the effect of demographic variables like gender, age, household income on the purchasing decision of LED has also been examined. A total 150 respondents were contacted visiting different outlet of electrical shops of Northern Delhi. The study may helpful for the companies to decide their marketing strategies to promote LED Lamps among the consumers with an aim to save energy and save environment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.8
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• pp.775-779
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• 2006

In this study, sputtered $Al_2O_3$ thin films were evaluated as a passivation layer in the process of InGaN-based blue LEDs in order to improve the brightness of LED lamps. In terms of packaged LED lamps, lamps with $Al_2O_3$ passivation layer emanated higher brightness than those with $SiO_2$ passivation layer, and LED lamps with 90 nm $Al_2O_3$ passivation layer were the brightest among four kinds of lamps. Although lamps with $Al_2O_3$ passivation had a slight increase in operating voltage, their brightness was improved about 13.6 % compare to the lamps made of conventional LEDs without the changes of emitting wavelength.

• Journal of Biosystems Engineering
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• v.36 no.5
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• pp.334-341
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• 2011

This study was conducted to compare the characteristics of heat dissipated from LED lamps with water cooling method and natural cooling method in a closed-type plant production system (CPPS) and to determine the optimum water temperature and flow rate for LED lamps with water cooling method. The experiments were performed in CPPS maintained at temperature of $24^{\circ}C$ and humidity of 70%. As compared to the LED lamps operated at water temperature of $22.5{\pm}1.2^{\circ}C$ and flow rate of $1,521{\pm}3.3\;mL{\cdot}min^{-1}$, air temperature under LED lamps with natural cooling was approximately increased by $1^{\circ}C$ and photosynthetic photon flux was decreased by $10{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. PPF illuminated from LED lamps was affected by forward voltage varied by the surface temperature of LED lamps. Forward voltage of LED lamps was decreased with increasing surface temperature and then PPF was proportionately decreased. Five levels ($14^{\circ}C,\;17^{\circ}C,\;20^{\circ}C,\;23^{\circ}C,\;26^{\circ}C$) of water temperature and three levels ($500\;mL{\cdot}min^{-1}$, $1,000\;mL{\cdot}min^{-1}$, $1,500\;mL{\cdot}min^{-1}$) of flow rate were provided to analyze the change of surface temperature and heat exchange of LED lamps. Heat exchange was increased with decreasing water temperature and increasing flow rate. At flow rate of $1,000-1,500\;mL{\cdot}min^{-1}$ and water temperature of 22.0-$22.6^{\circ}C$, surface temperature of LED lamps can be approached to $24^{\circ}C$ that was almost same as air temperature in CPPS. The calorific value generated from LED lamps used in the study was estimated to be $103.0\;kJ{\cdot}h^{-1}$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.7
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• pp.1-7
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• 2013

LED lamps are appropriate to the light source for use in broadcasting lighting. When the lighting frequency of LED lamp is different from the shutter frequency of camera, however, the flicker appears on the moving image which is taken by the camera under the dimmed light of LED lamp with conventional dimming methods. In this study, a new dimming method for the LED lamps used as the broadcasting lighting is proposed to minimize the flicker. A lighting period in the proposed dimming method is divided into the several sub-periods which have weight of the bits. Also, the proposed dimming method has characteristics that are optimizing the turn-on timings of two LED lamps to reduce the turn-off periods of the lamps and not to overlap the turn-on periods of the lamps. In the experiments, the incidence of the flicker is taken by the camera under several lighting conditions of the conventional dimming methods and the proposed dimming method. In addition, the brightness values of the frames are obtained in the moving image, and incidence of the flicker is evaluated and compared with conventional methods. From the results, the incidence of the flicker in the proposed method is more improved than the conventional methods.