• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1882-1884
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• 1999

The photoisomerization of functional polyimide was investigated in the various temperatures and UV(360nm) & visible(450nm) light irradiation. The absorption spectrum of azobenzene containing polyamic acid in a mixture of N,N-dimethylacetamide and benzene(1:1 by volume) solution was induced photoisomerization by UV and visible light irradiation. The absorption spectrum of LB films are also induced photoisomerization by UV and visible light irradiation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.05a
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• pp.111-114
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• 1995

This paper describes the imidization of PAAS(polyamic acid alkylamine salts) Langmuir-Blodgett (LB) films and the electrical properties of PAAS and polyimide(PI) LB films, The imidization conditons were investigated by TGA(Thermal Gravi-tational Analysis). FT-IR and UV/ visible absorption spectra. A thermal imidiczation was peformed at 300$^{\circ}C$ for 1 hour. The electrical properties of the PAAS and polymide LB films were measured by current-voltate(L-V) characteristics It shows that the electrical condcutivity of PL LB films is about 10 $\^$-15/S/cm which is two orders of magnetiude lower than that of the PAAS LB films A Schottky effect was also observed in both films.

• Journal of the Korean Applied Science and Technology
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• v.22 no.3
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• pp.228-233
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• 2005

Langmuir-Blodgett(LB) technique can speak the best candidate of the future molecular electronic devices. But, precursor as molecular ultrathin film devices require the bulk property that are influenced by the molecular orientation. So, this device is one of current interest in molecular electronic device development of new materials. In this study, quantitative evaluation of molecular orientation in LB films of polyamic acid alkylamine salt was performed analysis experiment comparing the absorption or transmission intensity of the FT-IR spectrometer and reflection or absorption spectra with UV-visible absorption spectra. It could find that the polar angle(${\theta}$) of the dipole moment appears in about $68^{\circ}$ and the tilting angle of the alkyl chain is about $11.5^{\circ}$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.139-141
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• 2007

Thin films of polyimide (Pl) were fabricated by a vapor deposition polymerization method (VDPM) and studied for the photosensitive characteristic. Polyamic acid (PAA) thin films fabricated by vapor deposition polymerization (VDP) from 6FDA and 4-4' DDE were converted to PI thin films by thermal curing. From AFM and Ellipsometer experimental, the films thickness was decreased and the reflectance was increased as the curing temperature was increased. Those results implies that thin film is uniform. From UV-Vis spectra, PI thin films showed high absorbance in 225 $\sim$ 260 [nm] region.

• Journal of the Korean Applied Science and Technology
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• v.15 no.2
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• pp.33-39
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• 1998

Displacement current measuring technique has been applied on the study of monolayers of functional polyimide containing azobenzene derivatives. The displacement current was generated from monolayers on the water surface by monolayer compression and expansion. Displacement current was generated when the area per molecule was about $70{\AA}^2$ and $100{\AA}^2$. Displacement currents were investigated in connection with monolayer of long chain alkylamines. It was found that the maximum of displacement current appeared at the molecular area just before the initial rise of surface pressure in compression cycles of polyamic acid and long chain alkylamines.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.277-280
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• 1997

It is important to investigate the molecular arrangement and the orientational distribution in the study of LB films. Polarized UV/visible absorption spectra make it possible to reveal the molecular arrangement and the orientational distribution. It is clarified that the PAAS LB films have specific directions in the molecular arrangement and the orientational distribution, which art different in intensity corresponding to the surface pressure. Unpolarized UV/visible absorption spectra reveal that the surface pressure is proportional to the finn thickness and is related to the molecular orientation. Current-Voltage(I-V) measurements provide that the current decreases as the surface pressure increases and there are certain phenomena called switching phenomena. Switching effort indicates that the current flows in high conductivity during on-state and suddenly decreases into low conductivity during off-state.

• Journal of the Korean Applied Science and Technology
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• v.11 no.2
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• pp.151-155
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• 1994

Polyamic acid alkylamine (N, N-dimethylhexadecylamine)(PAAS)염을 합성하여 그 합성여부를 확인하였으며 PAAS염의 Langmuir막의 ${\pi}-A$ 등온선 및 표면 전위 특성 등을 조사 하였다. Langmuir-Blodgett법에 의하여 PAAS염의 LB막을 여러종류의 기관에 누적하였으며 누적여부를 자외선 흡수 스펙트럼 및 적외선 투과 스펙트럼을 이용하여 조사하였다. 그리고 PAAS LB막을 열처리에 의하여 이미드(imide)화시켜 폴리이미드 LB막을 제조하였으며 그 이미드화 여부를 자외선 및 적외선 스펙트럼을 이용하여 조사하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.1
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• pp.81-88
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• 2005

The Langmuir monolayers of polyamic acid salts with three kinds of alkyl chains have been investigated by means of conventional $\pi$-A isotherms and second harmonic generation measurements proposed in this paper. The surface molecular density dependence of second harmonic intensity clearly shows the region of aggregation while corresponding $\pi$-A isotherm doesn't show any changes in the surface morphology at the same region. The surface morphology analysis based on the second harmonic measurement was consistent with the Brewster angle microscope measurement results.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.2
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• pp.128-132
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• 2004

This paper presents the design, fabrication sequence and measurement results of a highly sensitive capacitive-type humidity sensor using a polyimide film without hydrophobic elements. The structure of the humidity sensor is MIM (metalinsulator-metal). For a high sensitivity, a modified aromatic polyimides as a moisture absorbing layer has been synthesized instead of using general polyimides containing hydrophobic elements. The polyimide film was obtained by synthesizing and thermally polymerizing polyamic acid composed of m-pyromellitic dianhydride, phenelenediamine and dimethylacetamide. Characteristics of fabricated sensors which include sensitivity, hysteresis and stability have been measured. The measurement result shows the percent normalized capacitance change of 0.37/%RH over a range from 10 to 90%RH, hysteresis of 0.77% over the same %RH range and maximum drift of 0.25% at 50%RH. The result shows that the developed humidity sensor can be applied to evaluate a hermeticity of various sensors and actuator systems as well as micro packages.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.972-973
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• 2007

Relationships between field effect mobility and grain size on pentacene thin-film transistors with $polyimide/SiO_2$ gate dielectrics have been studied. 6 kinds of polyimide were used as surface treatment gate dielectric layer. Grain size of the pentacene thin film were between 5 and $30\;{\mu}m$ and depended on the polyimide. The field effect mobility were also depended on the polyimide and the those values were from 0.027 to $0.69\;cm^2/(Vs)$. The field effect mobility tends to increase with increasing the grain size. Precursor type polyimide containing polyamic acid show better mobility of $0.69\;cm^2/(Vs)$ than soluble type polyimide. Bias stress characteristics in air are discussed in the basis of the grain size.