• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.477-482
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• 2007

This paper examines and analyzes improvement of structure of bulb, increase of luminous efficiency through application of reflector globe through aluminum coating and development of 60[W] basking neodymium lamp through optimum insertion ratio of krypton gas and nitrogen gas. The results of this development shows that the life of the lamp was 7,200 hours, and the luminous flux was 620[1m]. This brings in superior color temperature and superior color rendering index, which allows us to use that lamp for agricultural or general purpose.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.12
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• pp.585-587
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• 2005

In this paper, We studied two methods to measure optical characteristics of an electrodeless light source using the integrating sphere(diameter 1.5m). One is to use a center measurement method and the other is to use a side measurement method. As a result of analysis, a side measurement methode without auxiliary lamp is almost similar against a center measurement with auxiliary lamp to reduce a measurement of an error for luminous flux, luminous efficacy and spectral distribution etc. Therefore, Sample which cannot measured by reason of big size and heavy weight can be measured by a side measurement method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.465-466
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• 2007

In electrode-less lamp, The key point in creating an efficient light source based on RF discharge is to minimize the RF power loss in the RF coupler which for Anderson's type of RF lamp is due to losses in the ferrite core. This loss depends on the particular ferrite material, its size, geometry, frequency in this kind of inductive lamp shows that the correct choice of discharge current has a crucial effect on the core loss. In this study, we measured Ferrite temperature in normal state, then analyzed electrical and optical characteristics according to ferrite shape. We were able to know that was ferrite of the antenna had relate closely with temperature and luminous of the lamp. Also we appraised temperature and electrical, optical properties during turn on the lamp.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.1
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• pp.35-38
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• 2015

LEDs are considered to be an alternative for enhancement of energy efficiency, applied for numerous areas such as display, automotive headlight not only lights. Yellow phosphor is generally utilized with blue LEDs to generate WLED, $Y_3Al_{5}O_{12}:Ce^{3+}$ is typically used as the yellow phosphor. The phosphor, mixed with epoxy resin, has been used by being spread and hardened on the blue LED chip. This paste-based packaging gives rise to problems of degradation of phosphor by heat and decrease of luminous efficiency. Although phosphor plate is used instead of the epoxy-phosphor mixture to solve these problems, loss of luminous efficacy by total internal reflection inside the plate also should be solved. In this study, we coated the side of the plate with silver as one of the solution.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2002.11a
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• pp.3-8
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• 2002

In this paper, We measured an electric and optical characteristics for electrodeless fluorescent lamp system. We used the CCD(charged couple device) and Integrating Sphere Photometer to detect the accurate variation of data and got a characteristic of output voltage and current, luminance, luminous flux etc. And then we come to understand that the efficiency of electrodeless fluorescent lamps are similar to CFLs(compact fluorescent lamp) or HID(high intensity discharge lamp).

• Journal of the Ergonomics Society of Korea
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• v.7 no.1
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• pp.39-44
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• 1988

Because the moving visual acuity is less than the static visual acuity, a new headlight system was designed and manufactured to make reparation for that. Then the new headlight system was built in a passenger car and some experiment was achieved. When the car is accelerated the luminous flux of headlight is augmented. When the speed of the car was increasing, the new system was effective, but when the car was decelerated the system was less effective.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.5
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• pp.654-660
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• 2011

This paper dealt with a design guide of LED luminaires to replace the surface and watertight fluorescent lamp (FL) fixtures for naval vessels. Several standards such as Korean Industrial Standard (KS), Korea Defence Standard (KDS) and US Military Standard (MIL) were compared in terms of safety and performance of lighting fixtures. The electrical and optical characteristics like power consumption, total luminous flux, and illumination distribution of the FL fixtures were experimentally analyzed to acquire design rules for LED luminaires. Based on the results, four types of LED luminaires were fabricated, and we proposed a design guide of LED luminaires for naval vessels which save power consumption of 44~51 [%] and increase total luminous flux of 8~13 [%].

• Current Optics and Photonics
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• v.1 no.4
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• pp.389-395
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• 2017

This paper investigates a method to improve the lighting performance of white light-emitting diodes (WLEDs), which are packaged using two separate remote phosphor layers, a yellow-emitting YAG:Ce phosphor layer and a red-emitting ${\alpha}-SrO{\cdot}3B_2O_3:Sm^{2+}$ phosphor layer. The thicknesses of these two layers are $800{\mu}m$ and $200{\mu}m$, respectively. Both of them are examined in conditions where the average correlated color temperatures (CCT) are 7700 K and 8500 K. For this two-layer model, the concentration of red phosphor is varied from 2% to 30% in the upper layer, while in the lower layer the yellow phosphor concentration is kept at 15%. It was found interestingly that the lighting properties such as color rendering index (CRI) and luminous flux are enhanced significantly, while the color uniformity is maintained in a relatively close range to the one of one-layer configuration (measured at the same correlated color temperature). Besides, the transmitted and reflected light of each phosphor layer are revised by combining Kubelka-Munk and Mie-Lorenz theories. Through analysis, it is demonstrated that the packaging configuration of two-layer remote phosphor that employs red-emitting ${\alpha}-SrO{\cdot}3B_2O_3:Sm^{2+}$ phosphor particles provides a practical solution for general WLEDs lighting.

• Journal of The Korean Astronomical Society
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• v.35 no.1
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• pp.1-7
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• 2002

We have studied the long-term X-ray light curve (2-10 keV) of the luminous Seyfert 1 galaxy MCG-2-58-22 by compiling data, from various X-ray satellites, which together cover more than 20 years. We have found two distinct types of time variations in the light curve. One is a gradual and secular decrease of the X-ray flux, and the other is the episodic increase of X-ray flux (or flare) by a factor of 2-4 compared with the level expected from the secular variation. We detected 3 such flares in total; a representative duration for the flares is $\~$2 years, with intervening quiescent intervals lasting $\~$6-8 years. We discuss a few possible origins for these variabilities. Though a standard disk instability theory may explain the displayed time variability in the X-ray light curve, the subsequent accretions of stellar debris, from a tidal disruption event caused by a supermassive black hole in MCG-2-58-22, cannot be ruled out as an alternative explanation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.11
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• pp.1503-1512
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• 2002

From the view of the environmental protection against the use of fossil fuels, a great of efforts have been exerted to find an alternative energy source. Hydrogen may become an alternative However the product species of the hydrogen flame is only $H_2O$, which emits only non-luminous radiation so the radiation from it is much smaller than that for a hydrocarbon flame. In this study, the authors designed and fabricated a laboratory scale test furnace to study thermal characteristics of hydrogen-air diffusion flame. In addition. the effects of addition of reacting as welt as non-reacting solid particles were experimentally investigated. Among the total heat flux to the wall, about 75 % was occupied by radiation while 25% by convection. When the aluminum oxide (Al$_2$O$_3$) particles were added, the radiative heat flux was reduced due to heat blockage effects. On the other hand, the total as well as the radiative heat flux was increased when the carbon particles were seeded, since the overall temperature increased. The effects of swirl and excess air ratio were also examined.