• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1517-1522
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• 2011

Recently, application of LED luminaires has been issued for energy saving plan. In this paper, we carried out a study to replace a low efficacy sealed-beam lamp for headlight of railroad vehicles with LED luminaire. Electrical and optical characteristics of the sealed-beam lamp were analyzed and a LED headlight was designed and fabricated. Total luminous efficacy and rated power of the prototype LED headlight were 82 lm/W ; about 5 times higher, and 40W ; about 4 times lower than the sealed-beam lamp, respectively. Especially, lifetime of the sealed-beam lamp is short as 1,000 hours due to the evaporation and vibration of filament, but that of LED headlight is over 30,000 hours long.

• 조명전기설비학회논문지
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• 제24권9호
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• pp.1-7
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• 2010

Ceramic metal halide lamps have been widely used due to long lifetime, high luminous efficiency and good colour rendering. 35[W] ceramic metal halide lamps has very different characteristics between ignition state and steady state. The developed electronic ballast is satisfied to both ignition state and steady state characteristics by using a micro-controller. The proposed electronic ballast is consists of EMI filter, Full-wave rectifier, Active PFC, DBI(Dual Buck Inverter), Igniter and control circuit. It enables to supply both low-frequency rectangular wave voltage and current to the lamp by using DBI(Dual Bcuk Inverter) structure.

• Journal of Information Display
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• 제12권4호
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• pp.219-222
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• 2011

Iridium-(III)-bis[(4,6-di-fluorophenyl)-pyridinate-N,$C^2$' ]picolinate-based blue phosphorescent organic light-emitting diodes with different electron transport materials were fabricated. Each electron transport material had different electron mobilities and triplet energies. The device with 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene had the highest external quantum efficiency (20.1%) and luminous current efficiency (33.1 cd/A) due to its high electron mobility and triplet energy. The operational stability of each device was also compared with that of the others. The device with 2,2',2"(1,3,5-benzenetriyl)tris-(1-phenyl-1H-benzimidazole) was found to have a longer lifetime than the other devices.

• 산업기술연구
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• 제30권A호
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• pp.83-88
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• 2010

Recently, the LED lighting is widely used to illumination purpose due to its high luminous efficiency and the long life time. However, the light power and lifetime is reduced by junction temperature increment of LED. So it is important to measure the junction temperature accurately. In this paper, we proposed a new design and implementation method of high power LED junction temperature measurement circuit. The proposed circuit has two current sources which are a driving current source and a measurement is verified by experiment, and the result shows that the proposed circuit is appropriate to practical use.

• 산업기술연구
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• 제31권B호
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• pp.67-73
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• 2011

Ceramic metal halide lamps have been widely used due to long lifetime, high luminous efficiency and good colour rendering. In this paper, we developed dimming control system of electronic ballast for 70W ceramic metal halide lamp by using 1-10V interface. The proposed electronic ballast is consists of EMI filter, Full-wave rectifier, Active PFC, DBI(Dual Buck Inverter), Igniter and control circuit.It enables to supply both low-frequency rectangular wave voltage and current to the lamp by using DBI(Dual Bcuk Inverter) structure. By using 1-10V interface, the system that able to dimming the lamp is demonstrated by P-spice simulation and experimental results.

• 산업기술연구
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• 제29권B호
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• pp.187-191
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• 2009

Recently, we have used LEDs to illumination because it has a high luminous efficiency and prolong lifespan. However the light power and lifetime is reduced by junction temperature increment of LED. So it is important to measure the junction temperature accurately. In case of using a electrical method measuring junction temperature of LED. Temperature measurement errors are spontaneously generated because of a parasitic capacitances in LED. In this paper, we proposed a method that reducing LED's parasitic capacitance effects for electrical measurement. It was demonstrated by the experimental result that is more correct than established method.

• 조명전기설비학회논문지
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• 제16권1호
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• pp.106-113
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• 2002

본 연구는 방전쳄버내에 각종 가스의 압력(58.8-137.3[kPa]) 변화에 따른 순수가스인 Kr, Ar 및 $N_2$가스의 절연 특성을 조사하고, 혼합가스인 Ar/$N_2$및 Kr/$N_2$가스의 절연 특성과 비교하였다. 또한, 실용 백열전구내의 혼합가스에 위한 각종 특성을 조사하였다. 실험 결과, $N_2$가스의 압력변화에 따른 절연 특성은 큰 분자량을 가진 Kr 및 Ar가스에 비하여 증가되었으며, 가스의 압력이 증가됨에 따라 절인파괴전압은 증가되었다. Ar/$N_2$및 Kr/$N_2$가스의 절연파괴전압은 $N_2$가스의 혼합비가 적을수록 감소되었으며, Kr(70%)$N_2$(30%)가스의 코로나개시전압은 Ar(70%)/$N_2$(30%)가스에 비해 증가되었다. 일반 백열전구에 Ar(70%)/$N_2$(30%)가스인 경우에 비해, Kr(70%)/$N_2$(30%)가스에서 광속과 수명이 대략 94[lm] 및 380[hr]으로 증가되었다. 백열전구내의 냉각온도가 20[$^{\circ}C$]일 때 혼합가스 주입압력은 40[$^{\circ}C$])에 비해 대략 13[%] 증가되었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.781-783
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• 2009

We achieved high efficiency and long lifetime in small-molecule organic light-emitting diodes using a blend of polyaniline-based conducting polymer and a perfluorinated ionomer as a hole injection layer (HIL). The HIL formed by single spin coating greatly enhanced the surface work function and thus the hole injection from the anode, which resulted in great improvement in device luminous efficiency. We find that the solution processed HIL outperforms the conventional vacuum-deposited small molecule HIL in terms of the device performance.

• 전기학회논문지
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• 제59권12호
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• pp.2262-2267
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• 2010

In order to analyze the reason of wall blackening, which affect the decline of lifetime in a ceramic metal halide lamp, we carried out the deterioration of ceramic tubes by a change in operating conditions with arc tubes of two types of spherical and cylindrical, and we have confirmed the cause of wall blackening through the analysis of element composition and spectrum from SEM/EDS and spectrum analyzer. Wall blackening of tungsten was shown by sputtering from ignition in 20 minute on/off condition and wall blackening from chemical reaction between PCA wall and rare earth halides was shown significantly in a condition without on/off test. Especially, the wall blackening and the decline of luminous flux were reduced by inner convection in spherical type arc tube. Moreover, the color temperature and color coordinate were changed by reduction of emission spectrum of Dy which causes the chemical reaction with PCA wall.

• 조명전기설비학회논문지
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• 제30권3호
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• pp.30-38
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• 2016

In this research, a 6W white LED package with a Glass Remote Phosphor was developed to improve the life of an LED package. The Glass Remote Phosphor was fabricated by the Phosphor in Glass (PiG) method, wherein phosphor YAG:Ce was mixed with glass frit and then heat treated. A paste with 75wt.% of a phosphor substance and 25wt.% glass frit was coated on a glass substrate two times using the screen-printing technique and heat-treated at $800^{\circ}C$ ; this structure gave a luminous efficacy of 136.1lm/W, color rendering index of 74Ra, and color temperature of 5,342K, thus satisfying the requirements as a light source for lighting. Moreover, an IES LM-80 accelerated life test was conducted on the same LED package for 6,000h in order to estimate the L70 lifetime based on IES TM-21. The results showed guaranteed lifetimes of 213,000h at $55^{\circ}C$, 245,000h at $85^{\circ}C$, and 209,000h at $95^{\circ}C$.