• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04a
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• pp.121-124
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• 2000

Achieving red light-emitting diodes with high quantum and luminous efficiency is required to fabricate the full-color organic electroluminescence display. In this work, we report that devices with 2.3,7,8,12,13,17,18-Octaethyl-21H,23H-porphine palladium (II) (PdOEP), doped into tris(8-Hydroxyquinolinato)-aluminum (III) (Alq3) show a narrow deep red emission (670nm). In addition, PdOEP has been used as host material in which red dyes such as 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) doped in order to fabricate efficient red-emitting diodes.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.21-24
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• 2004

In this paper, we measured the optical characteristics of the electrodeless fluorescent lamp system as product of the inside and outside of the country and compared the measured data. Power consumption wave of domestic 150 W is unstable than it's of Endura 150 W. Optical characteristics(luminance, luminous flux, color rendering index, efficiency, CIE chromaticity coordinate) value of the former is a little small than the latter. In conclusion, if we improve a little more quality then we must secure the superiority in competition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.121-122
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• 2008

Blue emitting materials have been explored by various researchers. However, blue-emitting materials with high luminous efficiency, good color purity, and thermal stability are still much desired. In this study, we synthesized a new blue luminescent material, $SnDP(HPB)_2$ which is low molecular compound and thermal stability. The PL spectrum of $SnDP(HPB)_2$ was observed blue at the wavelength of 447nm. The ionization potential(IP) and the electron affinity(EA) of $SnDP(HPB)_2$ was measured to be 6.7 eV and 3.0 eV, respectively. The fundamental structure of the OLED was ITO/NPB/$SnDP(HPB)_2/Alq_3$/LiF/Al. As a Result, we obtained to enhance the performance of blue OLED.

• Journal of Astronomy and Space Sciences
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• v.1 no.1
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• pp.55-65
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• 1984

A total of 618 photoelectric observations (302 in yellow and 316 in bule) is made in 1982 at the Yonsei University Observatory. Except that of the secondary eclipse the homogeneous coverage of observations successfully secured B, V, and B-V light curves. Enhanced distortions in the light curves are appeared at the phases aroung $0.^P1$, which supports the wave-like migration period of 9.7 years(Rodono 1981). One epoch time of the primary minimum was made by combining the observations in three nights. This minimum time shows that the O-C values are still decreasing and there seems to indication of increasing. B and V light curves of the primary minimum are in strong asymmetry which show less luminous in the third and fourth contacts compared to those of the first and second ones. This asymmetry may be as a result of the reflection of the wave minimum at $0.^P1$, and B-V curve also shows asymmetry, redder at the third contact than the second one by about $0.^m04$. This color difference apperature distribution on the surface of cooler, larger component(KO IV star).

• Journal of Applied Reliability
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• v.12 no.3
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• pp.177-186
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• 2012

This paper presents a comparison of the failure mechanism for high power converted white LEDs(3W) with the commercially available YAG:Ce and silicate phosphor. We carry out the normal aging life test for 10,000 hours, the high temperature aging test for 8,000 hours, the high temperature and humidity aging test for 8,000 hours and the current aging testing for 5,000 hours. The optical and electrical parameters of LEDs were monitored, such as lumen, correlated color temperature (CCT), chromaticity coordinates(x, y), thermal resistance, I -V curve and spectrum intensity. The stress induced a luminous flux decay on LED in all experiments and causes a failure. So we try to find out what's a main failure mechanism for a high power LED.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.9
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• pp.8-17
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• 2012

This paper proposes high performance control of light emitting diode(LED) drive system for liquid crystal display(LCD) backlight. The CCFL(cold cathode fluorescent lamp)was used to a conventional LCD backlight. Due to improvement on luminous efficiency, long life and wide color gamut, LED has gradually substituted for CCFL as backlight. The backlight using LED is necessary to use many LED. For that reason, the LED backlight is using a lot of LED driving circuits. The many LED driving circuit is generated a current deviation between LED. Eventually, it is caused brightness deviation between LED. Therefore, this paper improves the current deviation using transformer and balancing capacitor to solve this problem. Also, for accurate and uniform brightness control, this paper is applied the artificial intelligent control to a dimming control. This paper is compared with conventional system, and validity of this paper proves through that result.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.984-987
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• 2002

In this study, It is to synthesize PPV-copolymer and to make polymer electroluminesence device in single layer of ITO/PPV -copolymer/metal. and then it has been realized basic characteristics for display device through analysis and recognized application possibility by luminous material. PPV-copolymer is used spin coating method and electrode is evaporated of vacuum deposition method by changing materials. The result of experiment, The PPV-copolymer used this study emitted blue color, could be discovered a change of emttion characteristic by electrode material.

• Transactions of Materials Processing
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• v.21 no.2
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• pp.131-137
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• 2012

With the advantages of power savings, increased life expectancy and fast response time over traditional incandescent bulb, LEDs are increasingly used for many applications including automotive, aviation, display, and special lighting applications. Since the high heat generation of LED chips can reduce service life, degrade luminous efficiency, and cause variation of color temperature, many studies have been carried out on the optimization of LED packaging and heat sinks. In this study, a fin expansion type cooling device using heat pipe, instead of a solid aluminum heat sink, was designed for LED security lightings based on thermal resistance analysis. Numerical analysis and experimental validation were carried out to evaluate its cooling performance.

• KIEAE Journal
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• v.2 no.2
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• pp.33-38
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• 2002

There are a number of practical uses for devices which are capable of piping large amounts of light: illumination of areas where there would be maintenance, safety, or security problems with electronic light sources; piping sunlight into indoor areas for illumination; and the conversion of high luminous efficacy, good color quality, high intensity discharge lamps into more acceptable linear of area sources of light. Prism light guides are hollow structures which pipe light by means of total internal reflectin(TIR). These devices are unique in their ability to combine the efficiency of TIR with the relatively low cost of hollow structure. An important application stems from their ability to transform a point source of light such as an incandescent or discharge lamp into a linear or area source of light or illumination. We report the development of an economical, flexible prismatic film for fabricating the light guide wall. This guide geometries and films are currently under development.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.932-934
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• 2006

A relationship between discharge delay time and the aging method were investigated: A-Y (Address electrode - Scan electrode) aging and conventional X-Y(Common electrode - Scan electrode) aging with the variation of sustain voltage beyond self-erasing discharge. Although A-Y aging decreases discharge delay time, it has several drawbacks like non-uniformity of discharge, degradation of luminous efficiency and a color temperature. In a conventional aging condition which is carried out near the mid-margin voltage, discharge delay time is short in low voltage and high frequency condition. As an alternative to conventional voltage aging, high voltage aging is suggested which is carried out at self-erasing sustain voltage region. High voltage aging shows lower discharge delay time and fast aging speed than conventional voltage aging.