• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.10a
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• pp.79-81
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• 1988

The capacitance-voltage (C-V) characteristics of poly-Si gate MOS devices fabricated by Low-Pressure Chemical Vapor Deposition (LPCVD) system have been studied. In the case poly-Si gate, work function difference and surface state charge density was found lower than that of Al gate. This fact was identified from the C-V curves that flatband shift was shown small due to the hydrogen gas diffused into oxide in processing of alloy and the annealing effect in processing of poly-Si deposition.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1139-1143
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• 2014

The adsorption behavior of the sulphate ($SO{_4}^{2-}$) on the external surface of (5,0), (8,0), and (10,0) zigzag AlNNTs was studied by using density functional calculations. Adsorption energies in the nanotubes are about -8.59, -8.04, -8.60 eV with a charge transfer of 0.59, 0.48, 0.56|e| from the sulphate ion to the nanotubes, respectively. The adsorption energies indicated that sulphate ion can be absorbed strongly on the nanotubes. Therefore, these nanotubes can be used for adsorption of sulphate ion from the environmental systems. It was found that diameter of the AlNNTs has slight role in the adsorption of sulphate ion. The electronic properties of the nanotubes showed notable changes upon the adsorption process.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.26-26
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• 2000

High quality epitaxial Y2O3 thin films were prepared on Si(111) and (001) substaretes by using ion beam assisted deposition. As a substrate, clean and chemically oxidized Si wafers were used and the effects of surface state on the film crystallinity were investigated. The crystalline quality of the films were estimated by x-ray scattering, rutherford backscattering spectroscopy/channeling, and high-resolution transmission electron microscopy (HRTEM). The interaction between Y and Si atoms interfere the nucleation of Y2O3 at the initial growth stage, it could be suppressed by the interface SiO2 layer. Therefore, SiO2 layer of the 4-6 layers, which have been known for hindering the crystal growth, could rather enhance the nucleation of the Y2O3 , and the high quality epitaxial film could be grown successfully. Electrical properties of Y2O3 films on Si(001) were measured by C-V and I-V, which revealed that the oxide trap charge density of the film was 1.8$\times$10-8C/$\textrm{cm}^2$ and the breakdown field strength was about 10MV/cm.

• Bulletin of the Korean Chemical Society
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• v.21 no.4
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• pp.412-418
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• 2000

Association of cytochrome c with anionic membranes involved both electrostatic and hydrophobic interactions and their relative contributions depended on the physical state of the membrane and the redox state of cyto-chromec.Hydrophobic interaction was favored by the membranes in gel phase, by the membranes with a large curvature, and by the membranes with a high surface charge density. Ferrocytochrome c was less dissociable by NaCl than ferricytochrome c suggesting that a lower protein stability is beneficial for hydrophobic interac-tion.Hydrophobic interaction induced larger structural perturbations on cytochrome c as monitored by the loss of the Fe-Met bond and by the increase in the distance between heme and Trp-59. When bound to anionic mem-branes,spin-labeled cytochrome c showed an electron paramagnetic resonance spectrum with two or more components, providing a direct evidence for multiple conformations of bound cytochrome c.

• Bulletin of the Korean Chemical Society
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• v.16 no.2
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• pp.164-168
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• 1995

The band structure of nickel monoxide having a cation defect rock salt structure is calculated by means of the tight-binding extended Huckel method. The calculation is also made for the net charge, the DOS, the COOP, the electron density of the constituent atoms, and the O 1s binding energy shift when one of the adjacent nickel atoms is defected. It is found that the band gap near the Γ direction on the Brillouin zone is about 0.2 eV, and that all of the properties calculated including the electronic structure of the oxygen atom are more effectively affected by the surface defect than the inside one. The core O 1s binding energy shift is calculated by the use of valence potential method and the results are very satisfactory in comparison with the XPS experimental findings.

• Applied Chemistry for Engineering
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• v.33 no.3
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• pp.315-321
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• 2022

We firstly observed that activated carbon (AC) deposited by atomic-layer vanadium pentoxide (V₂O₅) was used as CDI electrodes to utilize the high dielectric constant for enhancing the capacitance equipped with atomic layer deposition (ALD). It was demonstrated that the vanadium pentoxide (V₂O₅) with sub-nanometer layer was effectively deposited onto activated carbon, and the electric double-layer capacitance of the AC was improved due to an increase in the surface charge density originated from polarization, leading to high ion removal in CDI operation. It was confirmed that the performance of modified-AC increases more than 200%, comparable to that of pristine-AC under 1.5 V at 20 mL min^-1 in CDI measurements.

• Electrical & Electronic Materials
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• v.11 no.10
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• pp.53-59
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• 1998

Paraelectric lead landthanum titanate(PLT) thin films have been prepared by a reactive dc magnetron sputtering system using a multicomponent metal target. The surface area control of each element on the target markedly facilitates the fabrication of thin films of complex ceramic compounds. A postdeposition heat-treatment was applied to all as-deposited PLT thin films at annealing temperatures up to 75$0^{\circ}C$ for crystalization. The composition of the PLT(28) thin filmannealed at $650^{\circ}C$ was: Pb, 0.73; La, 0.28; Ti, 0.88; O, 2.9. The dielectric constant and dissipation factor of the thin film(200 nm) at low filed measurements (500 Vcm-1) are 1216 and 0.018, respectively. The charge storage density using a typical Sawyer-Tower circuit with a 500 Hz sine wave was 12.5 $\mu$Ccm-2 at the electric field of 200 kVcm-1.

• Journal of Powder Materials
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• v.30 no.6
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• pp.528-535
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• 2023

Since their initial development in 2012, triboelectric nanogenerators (TENGs) have gained popularity worldwide as a desired option for harnessing energy. The urgent demand for TENGs is attributed to their novel structural design, low cost, and use of large-scale materials. The output performance of a TENG depends on the surface charge density of the friction layers. Several recycled and biowaste materials have been explored as friction layers to enhance the output performance of TENGs. Natural and oceanic biomaterials have also been investigated as alternatives for improving the performance of TENG devices. Moreover, structural innovations have been made in TENGs to develop highly efficient devices. This review summarizes the recent developments in recycling and biowaste materials for TENG devices. The potential of natural and oceanic biowaste materials is also discussed. Finally, future outlooks for the structural developments in TENG devices are presented.

• Journal of Industrial Technology
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• v.43 no.1
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• pp.43-48
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• 2023

Spinel LiNi_0.5Mn_1.5O₄ (LNMO) has been considered as one of most promising cathode material, because of its low-cost and competitive energy density. However, 4.7V vs. Li/Li⁺ of high operating potential facilitates electrolyte degradation on cathode-electrolyte interface during charge-discharge process. In particular, commercial polyvinylidene fluoride (PVDF) is not sutaible for LNMO cathode binder because its weak van der waals force induces thick and non-uniform coverage on the cathode surface. In this review, we study high performance binders for LNMO cathode, which forms uniform coating layer to prevent direct contact between electrolyte and LNMO particle as well as modifying high quality cathode electrolyte interphase, improved cell performace.

• Polymer(Korea)
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• v.28 no.3
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• pp.218-224
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• 2004

The adhesion and proliferation of mammalian cells on polymeric biomaterials depend on the surface characteristics such as wettability, chemistry, charge and roughness. In order to recognize the correlation between the adhesion and proliferation of human bone marrow derived stem cells (BMSCs) and surface property, radio frequency generated plasma treatment on low density polyethylene (LDPE) has been carried out. The modified LDPE surfaces were characterized by measuring the static water contact angle. The adhesion and proliferation of cells on LDPE films were characterized by cell counting and reverse transcription-polymerase chain reaction (RT-PCR). The water contact angle of the film surface decreased with plasma treatment time. Proto-oncogenes (c-myc, c-fos) and tumor suppressor gene (p153) showed maximum expression with contact angle of 60 ∼ 70$^{\circ}$ range of LDPE film. By cell counting, we confirmed that the rate of cell proliferation appeared the higher on the film surface of the contact angle of 60∼70$^{\circ}$ We concluded that the surface wettability is an important role for the growth and differentiation of BMSCs.