• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1247-1249
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• 1997

Langmuir-Blodgett(LB) method is one of the ways of fabricating organic ultra thin films. It is well known that It has the advantage to control the alignment and orientation of the molecules in the films. Metallo-phthalocyanines (MPcs) are sensitive to electron affinitive toxic gaseous molecules, such as $NO_2$, NO, $SO_2$. In this study, thin films of octa-dodecyloxy copper-phthalocyanine were prepared by LB method and characterized by using UV/Vis absorption spectroscopy and ellipsometry. Optimal transfer condition of LB films was investigated and preliminary results of current-voltage (I-V) characteristics of these films exposed to $NO_2$ gas as a function of film thickness.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.9
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• pp.762-767
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• 2001

We report the white light emission from the multilayer organic electroluminescent(EL) device using exciplex emission. The exciplex at 500nm originated between poly(N-vinylcarvazole)(PVK) and 2,5-bis(5'-tert-butyl-2-benzoxazoly)thiophene(BBOT) and exciplex of 50nm originated from N,N'-diphenyl-N,N'-(3-methyphenyl)-1,1'-biphenyl-4,4'-diamine(TPD) and BBOT were observed. Also, the energy transfer from PVK to BBOT and poly(3-hexylthiophene)(P3HT) in mixed emitting materials was occurred. The electroluminescence(EL) spectra of organic EL device which have a device structure of ITO/CuPc(5nm)/emitting layer(100nm)/BBOT(30nm)/LiF(1.4nm)/Al(200nm) were slightly changed as a function of the applied voltage. The luminance fo 12.3 ${\mu}$W/$\textrm{cm}^2$ was achieved at 20V and EL spectrum measured at 20V corresponds to Commission Internationale de L\`Eclairage(CIE) coordinates of x=0.29 and y=0.353.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.1-4
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• 1997

In this study, ruin films of Octla-dodecyloxy copper-phthalocyanine were prepared by Langmuir-Blodgett (LB) method and characterirzed by using UV-Vis absorption spectroscopy and ellipsometry. [1],r[2] Optimal transfer condition of LB films was investigated and preliminary results of current-voltage(1-V) characteristics of these films exposed to NO$_2$ gas as were discussed functions of film thickness, temperature and NO$_2$ gas concentration.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.108-111
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• 2003

Currently, molecular devices are reported utilizing active self-assembled monolayers containing the nitro group as the active component, which has active redox centers[1]. We confirm the electrical properties of 4,4-di(ethynylphenyl)-2'-nitro-1-benzenethiolate. To deposit the SAM layer onto gold electrode, we transfer the prefabricated Au(111) substrates into a 1mM self-assembly molecules in THF solution. Au(111) substrates were prepared by ion beam sputtering method of gold onto the silicon wafer. As a result, we measured current-voltage curve using ultra high vacuum scanning tunneling microscopy (UHV STM), I-V curve also clearly shows several current peaks between the negative bias region (-0.3958V) and the positive bias region (0.4658V), respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.81-82
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• 2006

The purposes of the present study are to produce a high thermal efficient of oil-based nanofluids which can be used as ultra-high voltage transformer oil, and to investigate their thermal and physical properties under static and dynamic conditions. Three kinds of nanofluids are prepared by dispersing $Al_2O_3$ or AlN nanoparticles in transformer oil. The thermal conductivities of the nanoparticles-oil mixtures increase with temperature, particle volume concentration and thermal conductivity of solid particle itself. It was quite important to eliminate $H_2O$ as byproducts of esterification and excess oleic acid which did not form stable chemical bonds with powder surface to get high dispersion stability.

• Journal of Welding and Joining
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• v.16 no.3
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• pp.44-54
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• 1998

In this study a new arc sensor algorithm for automatic weld seam tracking was proposed, which uses the relative welding current variation according to the tip-to-workpiece distance in GMA welding. Since the new developed arc sensor algorithm is not sensitive to unstable factors of arc signal, the system is expected to get rid of the problems of already existing arc sensor system which include the difficulty of modeling the process for various welding conditions and limitation of application to thick plate welding. Thus the system is applicable not only to thick plate welding but also to thin plate welding. To implement the new arc sensor algorithm the system parameters which include sampling time, averaging range, weighting factor of moving averaging, basic compensation time, and basic compensation distance were determined by experimental analysis. Consequently this system has shown the successful tracking capability for the various welding conditions.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.139-141
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• 2005

It is possble to study charge transfer property which is caused by height variation because we can see the organic materials barrier height and STM tip by organic materials energy band gap. Here, we investigated the negative differential resistance(NDR) and charge transfer property of self-assembled 4,4-Di(ethynylphenyl)-2'-nitro-1-(thioacetyl)benzene, which has been well known as a conducting molecule. Self-assembly monolayers(SAMs) were prepared on Au(111), which had been thermally deposited onto pre-treatment($H_{2}SO_{4}:H_{2}O_{2}$=3:1) Si. The Au substrate was exposed to a 1 mM/l solution of 1-dodecanethiol in ethanol for 24 hours to form a monolayer. After thorough rinsing the sample, it was exposed to a $0.1{\mu}M/1$ solution of 4,4-Di(ethynylphenyl)-2'-nitro-1-(thioacetyl)benzene in dimethylformamide(DMF) for 30 min and kept in the dark during immersion to avoid photo-oxidation. After the assembly, the samples were removed from the solutions, rinsed thoroughly with methanol, acetone, and $CH_{2}Cl_{2}$, and finally blown dry with $N_2$. Under these conditions, we measured electrical properties of self-assembly monolayers(SAMs) using ultra high vacuum scanning tunneling microscopy(UHV-STM). The applied voltages were from -1.50 V to -1.20 V with 298 K temperature. The vacuum condition is $6{\times}10^{-8}$ Torr. As a result, we found that NDR and charge transfer property by a little change of height when the voltage is applied between STM tip and electrode.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.5
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• pp.46-54
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• 1984

A silicon-gate n-well CMOS process with 3 $\mu$m gate length was developed and its possibility for the applications was discussed,. Threshold voltage was easily controlled by ion implantation and 3-$\mu$m gate length with 650 $\AA$ oxide shows ignorable short channel effect. Large value of Al-n+ contact resistance is one of the problems in fabrications of VLSI circuits. Transfer characteristics of CMOS inverter is fairly good and the propagation delay time per stage in ring oscillator with layout of (W/L) PMOS /(W/L) NMOS =(10/5)/(5/5) is about 3.4 nsec. catch-up occurs on substrate current of 3-5 mA in this process and critically dependent on the well doping density and nt-source to n-well space. Therefore, research, more on latch-up characteristics as a function of n-well profile and design rule, especially n+-source to n-well space, is required.

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.376-383
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• 2005

We designed and fabricated integrated-optic tunable polarization controllers based on $LiNbO_3$ with the Ti-indiffused waveguide along the y-axis utilizing the electro-optic effect. The device consists of $TE↔TM$ mode converters and TE/TM phase shifters. We analyzed the operation principles of each device utilizing transfer matrices based on a Jones matrix and simulated shifting of the center wavelength by inducing voltage. We confirmed experimentally that the fabricated devices control the tunability of the center wavelength and the input SOP.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.11
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• pp.13-22
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• 2010

This paper proposed the dual-loops multiphase DLL based mixed VCO/VCDL for a high frequency phase noise suppression of the input clock and the multiple frequencies generation with a precise duty cycle. In the proposed architecture, the dual-loops DLL uses the dual input differential buffer based nMOS source-coupled pairs at the input stage of the mixed VCO/VCDL. This can easily convert the input and output phase transfer of the conventional DLL with bypass pass filter characteristic to the input and output phase transfer of PLL with low pass filter characteristic for the high frequency input phase noise suppression. Also, the proposed DLL can correct the duty-cycle error of multiple frequencies by using only the duty-cycle correction circuits and the phase tracking loop without additional correction controlled loop. At the simulation result with $0.18{\mu}m$ CMOS technology, the output phase noise of the proposed DLL is improved under -13dB for 1GHz input clock with 800MHz input phase noise. Also, at 1GHz operating frequency with 40%~60% duty-cycle error, the duty-cycle error of the multiple frequencies is corrected under $50{\pm}1%$ at 2GHz the input clock.