• Science of Emotion and Sensibility
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• v.13 no.1
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• pp.69-78
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• 2010

LED technology offers versatile lighting control while having a very low environmental impact. Consequently, increasing attention is being paid to the emotional impact of LED lighting. This study investigated whether the chromacity of LED lighting influences people's time perception. To this end, two empirical studies were conducted: First, in experiment I(N=28), the subjects compared their perception of the time duration, which was varied from 3s to 20s, for 6 chromatically nuanced lighting conditions, respectively, with that under a daylight condition. The results showed that, in warm-color nuanced lighting conditions, the subjects perceived time to pass more slowly than in the daylight condition. On the contrary, in cool-color nuanced lighting conditions, the subjects perceived time to pass more rapidly than in the daylight condition. Then, in experiment II(N=39), the subjects were asked to count for 90 seconds while simultaneously performing some cognitive tasks. Confirming the results found in experiment I, the subjects perceived time to pass more rapidly in cool-color nuanced lighting conditions than in warm-color nuanced lighting conditions, although the difference was not statistically significant(p>0.05). In addition, the subjects tended to perceive the time to be shorter when the nuanced color of the light was closer to their preferred color.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.168-173
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• 2011

Recently, from a saving energy and environmental lighting sources point of view, using LED lighting have been increased rapidly. The colors of light was applied to the control of dimmers that is composed of red, green, blue, and white(RGBW) to improve the quality of visual environment. Moreover this study has been processed to develop adjustable dynamic LED lighting system on SPD and definitize the various spectral power distribution and color temperature of light through the control of the four dimmers. It is possible to combine up to $432^4$ kinds of light. Measurement of illuminance of range on working surface was as 7~l,831 lux. Application of visual environment for occupants can be expected according to control of lighting performance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.1
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• pp.18-29
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• 2011

Light emitting diode(LED) technology has been increasingly developed and larger color gamut by LED illuminations can be reproduced; therefore more efficient LED lighting design can be accomplished under a consideration of color emotion. Fifty-two LED colors which are uniformly distributed on the uniform chromaticity space are evaluated in terms of fatigueness and preference and their relation to three color-appearance attributes(lightness, chroma and hue) are investigated. As a result, 23 human observers likely to prefer and feel comfortable, when lightness of a given LED color stimulus increases as well as its chroma decreases. The highest fatigueness score is observed in red color series and the most preferred LED color is found in green color series. In addition, fatigueness and preference show a strong negative linear relation and their Pearson correlation is higher than -0.8.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.1-7
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• 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 the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.721-729
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• 2012

In this paper, human sensibility is measured on multi-modal environment and a sensitivity lighting system is implemented according to driven emotional indexes. We use LED lighting because it supports ecological circumstance, high efficiency, and long lifetime. In particular, the LED lighting provides various color schemes even in single lighting bulb. To cognize the human sensibility, we use the image information and the arousal state information, which are composed of multi-modal basis and calculates emotional indexes. In experiments, as the LED lighting color vision varies according to users' emotional index, we show that it provides human friendly lighting system compared to the existing systems.

• Science of Emotion and Sensibility
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• v.17 no.3
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• pp.29-38
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• 2014

The purpose of this study was to verify human physiological responses to emotional lighting system using LED (light emitting diode) flat lighting. Subjects were ten males in their twenties without medical history to eyes. Colors of LED lighting are red, orange, yellow, green, blue, purple and colorless (white). They were stimulated by LED lighting for 5 minutes. We measured body temperature, heart rate variability (HRV) and electroencephalogram (EEG) before and after color stimulus. In case of EEG analysis, relative power ${\alpha}$ wave ratio decreased in the groups of colorless, red and orange color light. Also, sympathetic nerve was more activated than parasympathetic nerve and the body temperature was increased in the groups of colorless, red, orange, yellow color light. On the other hand, relative power ${\alpha}$ wave ratio increased and parasympathetic nerve was more activated than sympathetic nerve and the body temperature was decreased in the groups of green, blue and purple color light. The results imply that the LED color lighting system in the realistic experiment environment. In the future, studies with compounded both colors and modes according to situation or auditory as nature sound or olfactory as aroma will be required.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.12
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• pp.1-10
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• 2011

Recently medical facilities that can help to heal the interpretation have evolved as a healing space. Accordingly, the patient's emotional, psychological and social ward plan to meet the needs of the patient to recover is important. The medical team is also related to the nature of human life, so they are experiencing high stress levels compared to other professionals. However, most places don't consider the user's psychological behavior. The purpose of this study is to build user-friendly lighting environment using LED lighting. LED lighting is easy to adjust illuminance and color temperature, and it is can be implemented in the medical area.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.3
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• pp.1-6
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• 2014

We measured color rendering index(CRI) of a LED lamp for lighting for aging-time. We chose bulb type white LED lamp six samples and halogen lamp one sample and applied 220V, 60Hz to all the samples for 1,000hours at ordinary temperature. The CRI was measured every 20hours and the CRI change of the LED lamp was compared with the halogen lamp's CRI change. As time goes, efficiency of the halogen lamp decreased and the CRI maintained uniformly. The other hand, efficiency of the LED lamp decreased but the CRI increased. The CRI of the LED lamp has been stabilized since 600hours. The CRI change of the LED lamp was analyzed with a spectrum, color coordinate and color temperature.

• Journal of Digital Convergence
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• v.13 no.6
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• pp.267-273
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• 2015

Recently, a wide range of products incorporating cutting-edge technology are being introduced in various sectors of design. Belkin's WeMo or Phillips' Hue are representative examples. In this context, the color-responsive lighting bookcase is a design product that would satisfy the needs of contemporary consumers who seek entertainment in their purchases. By installing lightings that change color according to the user's behavior, this design reconceptualizes the bookcase as a source of entertainment rather than a mundane object of household furnishing. The lighting apparatus can be detached and reattached, serving as stand-alone equipment. The lighting bookcase is modularized, comprising extensions equipped with MCU (Micro Controller Unit), RGB LED and color sensors. The bookcase as a whole is extendable towards four directions up to nine units with the lighting bookcase at the center. The extended, multiple lighting bookcases are wired to receive power from the main bookcase, and are equipped with RGB LEDs but not with MCUs or color sensors. Receiving power and color signals from the main lighting bookcase, the sub-bookcases feature changing shades of color. Also, it includes IoT(internet of Things). This study is a proposal of a design product, modularized to control the shades of the bookcase lighting using these sensors.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.12
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• pp.920-923
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• 2013

In this paper, the characteristics of a carbon nanotube composite heat sink proposed to replace the advanced Al heat sinks for LED lighting devices were studied. Proposed CMP-PLA heat sink was made by mixing 20~70 wt% carbon nanotube, 20~70 wt% bio-degradable polymer of melt-blended PLA (poly lactic acid) and PBS (poly butylene succinate) and PLA nucleating agents composed of the mixture of soybean oil and biotites, at $150{\sim}220^{\circ}C$ with 1,000~1,500 rpm. Optical and electric characteristics of 7.5 W LED lighting devices using heat sinks with such prepared CMP-PLA were investigated. And, the properties of the heat, which was not released from the CMP-PLA type heat sinks, was also investigated. The color temperature of LED lighting devices using the CMP-PLA heat sinks was 5,956 K, which is x= 0.32 and y= 0.34 in the XY chromaticity, and the color rendering index was 75. The luminous flux and the luminous efficiency of LED lighting devices using the CMP-PLA heat sinks was 540.6 lm and 72.68 lm/W respectively. Measured initial temperature of the heat sinks was $27^{\circ}C$, and their temperature increased as time to be saturated at $52^{\circ}C$ after an hour.