• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.146-149
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• 1999

Langmur-Blodgett (LB) method has a unique characteristic of making molecularly mutilayered aggregation structures. LB method makes the thickness of organic insulation layer controllable at molecular scale in various electronic devices. In this study, the organic materials applicable to crosslinked LB insulation layers of electronic devices have developed and the electrical properties of their LB films have examined such as Brewster angle microscopy(BAM), Scanning Maxwell-stress microscopy(SMM), and Current-voltage(1-V) properties.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.3
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• pp.81-84
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• 2001

The trans and cis forms of N-alkyl-4-styrylpyridinium derivatives (CnSP: n= 4, 8, 12, 16) were successfully synthesized and purified. The derivatives of styrylpyridinium cause photoisomerization when they are illuminated with UV light. The pressure-area isotherms of CnSP and their derivatives were studied to reveal the effect of alkyl chain length. The photoisomerization of CnSP monolayers at the air/water interfaces was indirectly studied by measuring surface tension changes with photoirradiation on the water surface. The characteristics of CnSP were furthermore studied with UV-vis, surface pressure-area isotherms, surface potential-area isotherms, Brewster Angle Microscopy (BAM) at the air/water interface, and optical diffraction efficiency on the ultrathin films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.298-301
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• 1997

This paper describes the thermally stimulated current(TSC) measurements arachidic acid(AA) and polyamic acid alkylamine salts(PAAS) LB film, which is a precursor of polyimide(PI). The measurements were performed from room temperature to about 250$^{\circ}C$ and the temperature was increased at a rate of 0.02 $^{\circ}C$/s linearly[4]. It shows that peaks of TSC are observed at about 80$^{\circ}C$ in the arachidic acid and about 80$^{\circ}C$, 160$^{\circ}C$ in the PAAS LB films. The DSC and TGA of PAAS, arachidic acid are measure. Monolayer phases on the water subphase such as Langmuir(L) films and the phase transitions from gas phase to solid phase via liquid phase are observed using Brewster angle microscopy(BAM). BAM is also used to observe the Langemuir-Blodgett(LB) films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.263-264
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• 2006

본 연구에서는 Arachidic acid Langmuir-Blodgett (LB)막의 계면특성과 전기적 특성을 측정하였다. Arachidic aicd는 포화지방산으로 ($CH_3(CH_2)_{18}COOH$)의 구조를 가지며, 크기가 27.5[$\AA$]으로 $CH_3(CH_2)_{18}$의 소수기와 COOH의 친수기로 구성되어 있다. LB막은 박막제작시 배열과 배향의 제어가 용이하다. Chloroform을 용매로 하여 2[mmol/l]의 농도를 조성하여 ${\pi}-A$ 등온선을 통해 기체 상태, 액체 상태, 고체 상태를 관찰하였으며 편광각 현미경 (Brewster angle microscopy) 이미지를 통해 각 상태에서의 이미지를 관찰하였다. 또한 LB막의 제작시 사용되어진 ITO 기판은 친수처리 전 후의 접촉각의 측정을 통하여 막의 안정성을 확인하였다. 또한 LB막을 Metal/LB막/Metal 구조의 소자로 제작하여 전압-전류 특성을 측정하였다.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.1
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• pp.26-30
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• 2004

Orientation control of a polyoxometalate (POM) nanoparticle in its two-dimensional arrangement was attempted by Langmuir-Blodgett (LB) technique. For their uniorientation, two carboxyl groups were introduced on one side of the POM particle, and hydrophobic long chains were attached by esterification with the carboxyl groups (C18-POM). The C18-POM layer spread on water surface showed stability against surface pressure up to 60 mN/m. The pattern of the C18-POM isotherm was quite different from stearyl alcohol (C18-OH), while the POM itself did not show any development of surface pressure on water surface. The AFM images of C18-POM LB films showed some microcrystalline structures that were noticed as dot structures by Brewster angle microscopy. The microimages for C18-POM did not completely spread out as a monolayer on the water surface. The XPS spectra indicated the presence of POM structures and stearyl ester bonds formed from about 65% of the total carboxyls. The XRD spectra showed that the unioriented POMs were not positioned with the same lattice distance but rather in a wavy surface state.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.7
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• pp.287-291
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• 2002

We fabricated the crosslinked films using p-hexadecoxyphenol (p-HP), which is amphiphilic and can form polyion complexes with formaldehyde at the air-water interface. The behavior of polyion complexation at the air-water interface and the surface structure of LB films was investigated by Brewster angle microscope(BAM) and scanning Maxwell-stress microscope (SMM), respectively. Also, the electrical properties for crosslinking in phenol-formaldehyde LB films were investigated by measuring conductivity and dielectric constant. The conductivities of p-HP LB films are as follows: heat-treatment of 1% formaldehyde subphase(3.76$\times$10$^{-15}$ ~4.76$\times$10$^{-1}$5[S/cm])$\times$10$^{-14}$ ~1.74$\times$10$^{-14}$ [S/cm]). Also, relative dielectric constants of p-HP LB films were reduced from 6.76~7.84 (pure water) to 2.97~3.25 (heat-treatment of 1% formaldehyde subphase))

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.3
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• pp.49-52
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• 2001

The derivatives of spironaphthooxazine gause photoisomerization when they are illuminate with UV light. We investigated the photoisomerization of spironaphthooxazine derivatives for holographic memory. Langmuir-Blodgett (LB) films contain amphiphile spironaphthooxazine derivatives which can be applied in molecular devices by a change of molecular level energy and a refractive index. In order to investigate the photoisomerization of spironaphthooxazine derivatives at the air/water energy and a refractive index. In order to investigate the photoisomerization of spironaphthooxazine derivatives at the air/water interfaces, spironaphthooxazine derivatives with side alkyl chains were synthesized. The films of the spironaphthooxazine derivatives were characterized by the measurement of UV/vis spectroscopy, Brewster Angle Microscopy (BAM) and Atomic Force Microscopy (AFM). The monolayers of the spironaphthooxazine derivatives mixed with stearic acid were stable at the air/water interface and visualized by the measurement of BAM. The spironaphthooxazine derivative monolayers on the glass surface showed the maximum efficiency of diffraction as 0.99% by the measurement of holography.

• Microbiology and Biotechnology Letters
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• v.47 no.2
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• pp.303-309
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• 2019

Earlier studies by our group revealed that gallic acid in phytochemicals stimulated biofilm production in epiphytes, while caffeic acid in phytochemicals inhibited biofilm production in non-epiphytes. It is well documented that antimicrobial secretion by some epiphytic bacteria inhibits non-epiphytic bacterial growth on leaf surfaces. These selection criteria help plants choose their microbial inhabitants. Calcium and iron in phytochemicals also stimulate biofilm formation and thus, may be selection criteria adopted by plants with respect to their native epiphytic population. Furthermore, the processing of leaves during phytochemical extraction impacts the composition of the extract, and therefore its ability to affect bacterial biofilm formation. Computation of the Hurst exponent using biofilm thickness data obtained from the Ellipsometry of Brewster Angle Microscopic (BAM) images is an efficient tool for understanding the impact of phytochemicals on epiphytic and non-epiphytic populations when compared to fluorescent microscopy, scanning electron microscopy, and staining techniques. To the best of our knowledge, this is the first report that uses the Hurst exponent to elucidate the mechanism involved in plant microbe interaction.

• Korean Journal of Materials Research
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• v.5 no.7
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• pp.781-785
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• 1995

from the $K_{6}$P$_4$ $O_{13}$ flux using a temperature cooling method. According to SHG outpower measurement, phase matching angle is $\theta$=90$^{\circ}$, $\Phi$=23.3$^{\circ}$and angular acceptance of $\Phi$ direction is about 2 degree, Deviation of phase matching angle due to index inhomogeneity in KTP crystal is 0.17 degree. A 20mW green laser was obtained with the combination of a intracavity Nd ; YAG and KTP crystal.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.6
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• pp.216-219
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• 2003

A new class of carbosiloxane dendrimer (G4-48PyP) terminated with 4-pyridylpropano I was synthesized and its possible application to functional thin films was examined through metal complexation and Langmuir-Blodgett (LB) technique. The highly concentrated periphery pyridyl groups of G4-48PyP were exposed on aq. aluminum ions at the air-water interface. The monolayers showed stability up to ca. 50 mN/m of surface pressure. When the subphase became acidic or alkaline, the monolayers changed to condensed phase. The presence of aluminum ions also caused reduction of the molecular area. The macroscopic images of the monolayers were monitored by Brewster angle microscopy (BAM) and only the images of dendrimer aggregates could be observed after the monolayer collapse. The surface images of the monolayer LB film were scanned by atomic force microscopy (AFM). The convex structures of single and aggregate molecules were directly observed. The structures of Langmuir-Blodgett (LB) films were characterized by FT-IR, UV-Vis, and X-ray photoelectron spectroscopy (XPS). The UV-Vis spectrum of the aluminum ion-complexed LB film showed additional band around 670nm, which was not found in the spectra of dendrimer itself or aq. aluminum ions. XPS spectra also supported the incorporation of aluminum ions into the LB films.