• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1248-1254
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• 2003

Carbon nanotubes(CNTs) are grown by using Co catalyst metal. CNTs fabricated by PECVD(plasma enhanced chemical vapor deposition) method are studied in terms of surface reaction and surface structure by TEM and Raman analysing method and ate analysed in its electrical field emission characteristics with variation of space between anode and cathode. Acetylene(C$_2$H$_2$) gas is used as the carbon source, while ammonia and hydrogen gas are used as catalyst and dilution gas. The CNTs grown by hydrogen(H$_2$) gas plasma indicates better vortical alignment, lower temperature process, and longer tip, compared to that grown by ammonia(NH$_3$) gas plasma. The CNTs fabricated with Co(cobalt) catalyst metal and PECVD method show the multiwall structure in mid-circle type in tip-end and the inner vacancy of 10nm. Emission properties of CNTs indicate the turn-on field to be 2.6 V/${\mu}{\textrm}{m}$ We suggest that CNTs can be possibly applied to the emitter tip of FEDs and high brightness flat lamp because of low temperature CNTs growth, low turn-on field.

• Transactions on Electrical and Electronic Materials
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• v.8 no.6
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• pp.268-273
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• 2007

In this study, It was studied about the luminance characteristics of 17 inch direct-type back light using EEFL(external electrode fluorescent lamp) and CCFL(cold cathode fluorescent lamp). The EEFL has a long life time because the electrode is installed outside of lamp. And it is produced in lower price than conventional CCFL. Moreover, it does not need process of installing internal electrode. However, the EEFL technology has several problems such as difficulty of designing driving inverter and preventing this phenomenon along the skin of lamps. We suggested two types of backlight unit for LCD TV application using the EEFL and the CCFL. We found optimized optical design parameters. We set the optical variation parameters such as lamp height, lamp distance, total thickness, and angles of inner walls. We achieved 7580 nits of center luminance, 82% of luminance uniformity by using 20 lamps of the EEFL and 7297 nits of center luminance, 78% of luminance uniformity by using 16 lamps of the CCFL.

• Journal of the Korean Ceramic Society
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• v.44 no.6 s.301
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• pp.303-307
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• 2007

Transparent In-doped zinc oxide (IZO) thin films are deposited with variation of pulsed DC power at Ar atmosphere on coming 7059 glass substrate by pulsed DC magnetron sputtering. A c-axis oriented IZO thin films were grown in perpendicular to the substrate. The optical transmittance spectra showed high transmittance of over 80% in the UV-visible region and exhibited the absorption edge of about 350 nm. Also, the IZO films exhibited the resistivity of ${\sim}10^{-3}{\Omega}\;cm$ and the mobility of ${\sim}6cm/V\;s$. Organic Light-emitting diodes (OLEDs) with IZO/N,N'-diphenyl-N, N'-bis(3-methylphenl)-1, 1'-biphenyl-4,4'-diamine (TPD)/tris (8-hydroxyquinoline) aluminum ($Alq_3$)/LiF/Al configuration were fabricated. LiF layer inserted is used as an interfacial layer to increase the electron injection. Under a current density of $100\;mA/cm^2$, the OLEDs show an excellent efficiency (9.4 V turn-on voltage) and a good brightness ($12000\;cd/m^2$) of the emission light from the devices. These results indicate that IZO films hold promise for anode electrodes in the OLEDs application.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1077-1080
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• 2009

In this paper, we propose a new method for measuring image sticking of an OLED display using a human visual test. We determined that the perceptual image sticking threshold is 2% of luminance difference at 200 nits and 1% at 100 nits, respectively. Color shift must also be considered when evaluating image sticking, as a ${\Delta}$(u', v') shift of just over 0.002 can be recognized regardless of background brightness. Perception of image sticking is affected by the background level, test pattern, and ambient illumination conditions. The evaluation standard must consider both luminance variation and color shift simultaneously.

• Journal of Information Display
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• v.7 no.3
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• pp.19-22
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• 2006

White polymeric light-emitting devices (WPLEDs) have been fabricated from polyfluorene-based (PFO) blue and MEH-PPV polymer blending systems. A device structure of ITO / PEDOT:PSS / Blending polymer / Blue polymer / LiF / Al was employed. This structure of double emission layers showed significant improvement of white color shift phenomenon. A current efficiency of 4.67 cd/A (3,900 $cd/m^{2}$, 6.4 V) and a brightness value of 17,600 $cd/m^{2}$ at 9.4 V with (0.34, 0.35) CIE coordinates at 5 V and (0.29, 0.29) at 9 V were achieved achieved.

• Journal of Information Display
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• v.12 no.1
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• pp.51-55
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• 2011

Efficient two-color-mixed white organic light-emitting diodes are presented herein by employing a sky-blue phosphorescent dopant of iridium(III)bis[4,6-(difluorophenyl)-pyridinato-N,$C^{2'}$]picolinate (FIrpic) and an orange phosphorescent dopant of bis(2-phenylquinoline)(acetylacetonate)iridium(III) ($Ir(phq)_2$acac) on the emissive layer. Very stable color variation under ${\Delta}$0.02 until a 5000 cd/$m^2$ brightness value was realized by efficient carrier control in a multi-stacked emitting layer of blue/red/blue colors. Maximum current and power efficiencies of 23.8 cd/A and 22.9 lm/W in the forward direction were obtained. With balanced emission from the two emitters, the white-light emission of high correlated color temperature of 7308K and the Commission Internationale de I'Eclairage coordinates of (0.30, 0.33) were achieved.

• KIEAE Journal
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• v.7 no.5
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• pp.35-40
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• 2007

The purpose of this study is to execute evaluation experiment to know the evaluation property of lighting environment of residential space for senior people, considering visual characteristics along aging, and finally provide basic data for the lighting plan to ensure the visual amenity. Processes of this study are as follows;1) Analyzed the variation property of visual sensibility and visual ability of senior people along aging. 2) Selected 3 types of life behavior(rest, conversation and reading) after checking life behavior in residential space for senior people based on advanced study. 3) Made the Mock-up Model that Dimming is possible, actual furnace to model. 4) Executed sensitivity evaluation experiment about lighting environment. 5) Analyzed evaluation property of lighting environment of residential space for senior people. Results of this study are as follows, 1) With lens-filter, we got comfort and amenity in bulb-color lamp which has similar color temperature with red of lens filter. 2) Lighting environment tests during conversation : With lens filters, they felt comfort on bulb color in case of higher illuminance than 850lux and daylight color in 500lux. 3) Lighting environment tests at reading : With lens filter, bulb color got better score in brightness and appropriateness than daylight color.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.11
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• pp.2779-2785
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• 2014

Edge Detection is a technique that obtains the particular information of the image using the brightness variation of pixel values and utilized for preprocessing in various image processing sectors. The conventional edge detection methods such as Sobel, Prewitt and Roberts are processed by applying the same weighted value to the entire pixels regardless of pixel distrbution and provides somewhat insufficient edge detection results. therefore, this paper has proposed an edge detection method considering the direction and magnitute of pixels by applying a modified directional mask.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.50-56
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• 2002

When the plasma panel is used as a display, frequent discharging are made to occur by alternatively charging each side of the panel to a critical voltage, which causes repeated gas discharges to occur. In this paper, an efficient sustain driver is proposed to achieve a faster rise-time in order to be suitable to widely used ADS driving method. The proposed circuit increases an operational margin up to 20 % compared with conventional approaches improving the recovery efficiency regardless of the variation of panel capacitance. Thanks to the increased operational margin, the brightness decrease problem can be solved without a limitation to sustain pulse width. The principle of operation, and features are illustrated, and verified on a 7.5 inch diagonal panel at 200 kHz operating frequency - based on experimental prototype.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1266-1268
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• 1996

In this study an automatic roiling-coli labeling system using robot vision system and peripheral mechanism is proposed and implemented, which instead of the manual labor to attach labels Rolling-coils in a steel miil. The binary image process for the image processing is performed with the threshold, and the contour line is converted to the binary gradient which detects the discontinuous variation of brightness of rolling-coils. The moment invariants algorithm proposed by Hu is used to make it easy to recognize even when the position of the center are different from the trained data. The position error compensation algorithm of six degrees of freedom industrial robot manipulator is also developed and the data of the position of the center rolling-coils, which is obtained by floor mount camera, are transfered by asynchronous communication method. Therefore even if the position of center is changed, robot moves to the position of center and performs the labeling work successfully. Therefore, this system can be improved the safety and efficiency.