• Journal of the Korean Solar Energy Society
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• v.31 no.2
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• pp.113-119
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• 2011

LED lighting has received much attention in recent years due to its high energy efficiency and environmental friendliness. As the color of light can be obtained by adjusting the light intensity of LEDs, the quality of visual environment can be improved. The aims of this study are to develop a wavelength adjustable LED lighting system and to examine its lighting performances. The LED lighting system and experimental cell for assessment of the lighting performance were constructed. This LED lighting system is able to materialize the various spectral power distribution and color temperature of light through the control of the four dimmers. Up to $432^4$ kinds of light combinations are possible. The range of illuminance on workplane were measured as 7~1,831 ㏓. Improvement of psychological and physical functions for occupants can be expected according to control of lighting performances.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.2
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• pp.163-168
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• 2003

The eye sensitivity in the difference conditions of a light source intensity consists of two functions by the receptor of cone and rod according to a wavelength. We derived a distribution function of $P{\lambda}=A{\cdot}e^{-({\lambda}-{\lambda}_u)^2/2W^2}$ using a respond probability of the receptor of cone-rod for a photon. It was well applied for a CIE eye's sensitivity curve of a wavelength. When there is lens In front of eye, luminous efficiency should be corrected. Transmission light which permeate to depends on absorption wavelength, and relationship of final luminous efficiency's estimation method is expressed by multiplication of luminous efficiency and transmittance intensity of lens. $$Pf({\lambda})=T({\lambda}){\cdot}P({\lambda})$$. The theory was applied to photopic and scopic vision with brown color lens.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1271-1276
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• 2008

This study has explained about LED for BLU which is widely used in the kinds of display devices or lighting. It was shown that the open due to delamination were the dominant LED for BLU failure mode and mechanisms from failure analysis of LED samples. Then, we have defined failure as yellowing and 100% reduction of light output intensity of LED for BLU and acceleration factors as temperature and current in Accelerated Life Test(ALT). Finally, we have estimated the Weibull distribution, life-stress relationship, and accelerating factor is used by ALTA Software.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.3-7
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• 2006

Development of light sources has been constantly grown for a high efficacy and long life. And, the design of luminaires has ben developed for the reflection and refraction of light mechanism. But it has been not enough to study for the refraction of light mechanism. Therefore, this study aims to study for the refraction of light mechanism to using Monte-Carlo method and Ray-tracing method. In addition, the purpose of this study is to shu calculation process for development of 3 dimensional planar prism design algorithm in orer to use the results of photometric data that is able to obtain various luminous intensity distribution.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.166-174
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• 1998

The distribution of oil film thickness in piston were measured by induced fluorescence method. A Xe lamp was used as light source. Coumarine-6 was mixed with oil as the fluorescent dye. Fluorescent signal which is proportional to the oil film thickness was acquired by CCD camera and transmitted to the personal computer as video signal. In order to solve the problem of measurement system, irregular distribution and unstability of light intensity, as well as to know the relationship between the oil film thickness and output signal, three different calibration techniques were used. Motoring and firing tests were performed in a single cylinder research engine with transparent liner. By analyzing the oil film thickness converted from the photographed image, it was observed that each of three piston rings scrapes the oil both upward and downward and oil film thickness is not uniform horizontally at a given piston land. The amount of oil in each land was considerably affected by the engine load. It is thought that the blow-by gas blows the oil down to the crankcase.

• Current Optics and Photonics
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• v.1 no.2
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• pp.85-89
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• 2017

It is shown that polarization singularities of a new type, namely U and P singularities, arise at the transverse cross section of a partially coherent beam, instead of the common singularities such as C points and L lines in a completely coherent vector field. A relationship between the two kind of singularities with respect to intensity is proposed. We also present a setup that can generate the new singularities, and any desired distribution of degree of polarization, using intensity control.

• Journal of Photoscience
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• v.9 no.2
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• pp.326-328
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• 2002

In many plant cells, the positions of chloroplasts change in response to changes in light conditions. In the epidermal cells of the aquatic angiosperm Vallisneria gigantea, the avoidance response of chloroplasts is induced specifically by irradiation with blue light of high intensity. Possible roles of actin cytoskeleton in the blue-light-induced avoidance response of chloroplasts were investigated by partial irradiation and phalloidin staining. We showed that the blue-light-dependent redistribution of chloroplasts was induced only in the limited area, where exposed to blue light, even in individual cells. In addition. in the exposed area, the configuration of actin filaments strikingly changed compared with that before the irradiation. Short and thick bundles of actin filaments surrounding the chloroplasts changed to much longer and thinner bundles with a more stretched array. In contrast, in the unexposed area, neither the distribution of chloroplasts nor the configuration of actin filaments exhibited any changes. Cytochalasin D and latrunculin B inhibited the avoidance response of chloroplasts concomitantly with the fragmentation of actin filaments. These results indicate that the reorganization of actin filaments plays a crucial role in the induction of avoidance response of chloroplasts.

• Korean Journal of Food Science and Technology
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• v.47 no.6
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• pp.785-788
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• 2015

In this study, the effect of light irradiation on tyrosinase activity during storage in a low temperature incubator was investigated, with the goal of identifying the appropriate wavelength and intensity of light for inhibiting tyrosinase activity. Fluorescent light and blue light emitting diode (LED) irradiation were found to inhibit tyrosinase activity. In particular, tyrosinase activity was significantly inhibited under high intensity blue LED irradiation, suggesting that the activity of tyrosinase present in vegetables or fruits might be inhibited by LED irradiation. Therefore, blue LED irradiation during food storage and the distribution stage would be useful for ensuring good quality of food, owing to the inhibition of the enzymatic browning reaction.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.16 no.1
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• pp.37-42
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• 1980

The purpose of the present study is to find the color induced maximum gathering rate and to observed'the trend of the - gathering rate by using two species of commercial fishes: rock bream, Oplegnathus fasciatus (Temminet et Schlegel) and 'grass puffer, Fugu niphobles (Jordan et Snyder). An experimental tank($360L{\times}50W{\times}55H cm$) was set up in a dark room. An illumination system was attached to the two end of tank to fix horizontal light intensity by co~bination c' one light bulb(20W) and four filters (red, blue, yellow, white) and the five regulating filters in order to fix light intensity. During the experiment water depth was maintained 50 cm lever in the tank. The tank was marked into six longitudinal sections each being 60 em long to observe the distribution of fish. The fish were acclimatized in dark condition for 40 minutes prior to the main experiment. Upon turning on the light, the number of fish in each section was counted 40 times every 30 seconds, and the gathering rates ,were obtain from the average number of fish in each secion. The color induced maximum gathering rate of rock bream appeared to be red, blue yellow and white color orderly.However, that of grass puffer appeared to be blue, white, yellow and red color orderly. Trend of the gathering rate in illumination time showed the remarkable fluctuation in the rock bream and little difference at the two color light sources. However, trend of the gathering rate in illumination time showed the little fluctuation in grass puffer and much difference at the two color light sources.

• Journal of the Korean Applied Science and Technology
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• v.15 no.4
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• pp.11-20
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• 1998

The propagation of light radiation in a turbid medium is an important problem that confronts dosimetry of therapeutic laser delivery and the development of diagnostic spectroscopy. Scattered light is measured as a function of the position(distance r, depth z) between the axis of the incident beam and the detection spot. Turbid sample yields a very forward-directed scattering pattern at short range of position from source to detector, whereas the thicker samples greatly attenuated the on-axis intensity at long range of position. The portions of scattered light reflected from or transmitted throughphantom depend upon internal reflectance and absorption properties of the phantom. Monte Carlo simulation method for modelling light transport in tissue is applied. It uses the photon is moved a distance where it may be scattered, absorbed, propagated, internally reflected, or transmitted out of tissue. The photon is repeatedly moved until it either escape from or is absorbed by the phantom. In order to obtain an optimum therapeutic ratio in phantom material, optimum control the light energy fluence rate is essential. This study is to discuss the physical mechanisms determining the actual light dose in phantom. Permitting a qualitative understanding of the measurements. It may also aid in designing the best model for laser medicine and application of medical engineering.