• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.230-233
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• 2004

The stochiometric mix of evaporating materials for the $CuInS_2$ single crystal thin films was prepared from horizontal furnance. Using extrapolation method of X-ray diffraction patterns for the $CuInS_2$ polycrystal, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were $5.524\;{\AA}$ and $11.142\;{\AA}$, respectively. To obtain the single crystal thin films, $CuInS_2$ mixed crystal was deposited on throughly etched semi-insulator GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperature were 640 t and 430 t, respectively and the thickness of the single crystal thin films was $2{\mu}m$. Hall effect on this sample was measured by the method of van dot Pauw and studied on carrier density and temperature dependence of mobility. The carrier density and mobility deduced from Hall data are $9.64{\times}10^{22}/m^3,\;2.95{\times}10^{-2}\;m^2/V{\cdot}s$ at 293 K, respectively The optical energy gaps were found to be 1.53 eV at room temperature. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the thin film, we have found that the values of spin orbit coupling splitting ${\Delta}So$ and the crystal field splitting ${\Delta}Cr$ were 0.0211 eV and 0.0045 eV at 10 K, respectively. From PL peaks measured at 10K, 807.7nm (1.5350ev) mean Ex peak of the free exciton emission, also 810.3nm (1.5301eV) expresses $I_2$ peak of donor-bound exciton emission and 815.6nm (1.5201eV) emerges $I_1$ peak of acceptor-bound exciton emission. In addition, the peak observed at 862.0nm (1.4383eV) was analyzed to be PL peak due to donor-acceptor pair(DAP).

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.68-68
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• 2003

HP(2-20) (AKKVFKRLEKLEKLFSKIQNDK) derived from the N-terminus of Helicobacter pylori Ribosomal Protein L1 shows potent antimicrobial activity against bacterial, fungi and cancer cells without cytotoxic effect. In order to investigate the relationships between antimicrobial activity and the structures, several analogues have been designed and synthesized. The structures of these peptides in SDS micelles have been investigated using NMR spectroscopy and they revealed that analogue 3 has the longest, well-defined alpha-helix from Val5 to Trp19. NOESY experiments performed on HP and its analogues in nondeuterated SDS micelles show that protons in the indole ring of Trp16 are in close contact with methylene protons of SDS micelles. In order to probe the position of HP and its analogues relative to the SDS micelles, spin-labeled stearate was added. Large effects are observed for the chemical shifts and the intensities of Phe5, Glu9, Phe12, and Trp16 within the helix region by 16-doxylstearate. This result implies that 16-doxylstearate is located in the center of the micelles and the hydrophobic phase of the amphiphilic ${\alpha}$-helix is located in contact with the acyl chains of the micelles. Also, Lys3 and Lys4 at N-terminus and Lys20 at C-terminus may produce an optimal arrangement for electrostatic interactions between the sulfate head groups of the SDS and the positively charged lysyl N$\sub$3/$\^$+/. Interactions between the indole ring of Trp and the membrane, as well as the amphiphilic ${\alpha}$-helical structure of HP induced by Trp at the C-terminus may allow HP to span the lipid bilayer. These structural features are crucial for their potent antibiotic activities.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1313-1314
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• 2007

This paper presents organic thin-film transistors (OTFTs) with poly(3-hexylthiophene)(P3HT) semiconductor and several polymeric dielectric materials of poly(vinyl phenol)(PVP), poly(vinyl alcohol)(PVA), and polyimide(PI) by using soluble process. The fabricated OTFT's have inverted staggered structure using transmission line method(TLM) pattern. In order to evaluate the electrical characteristics of the OTFT, capacitance-voltage(C-V) and current-voltage(I-V) were measured. C-V graphs were measured at several frequencies of 100 Hz, 1 kHz, and 1 MHz and ID-VDS graphs according to $V_{GS}$. The current on/off ratio and threshold voltage with each of PVP, PVA, and PI based OTFTs were measured to $10^3$, and -0.36, -0.41, and -0.62 V. Also, the calculated mobility with each of PVP, PVA, and PI was 0.097, 0.095, and 0.028 $cm^{2}V^{-1}s^{-1}$, respectively. In the cases of PVP and PVA, the hole mobility of P3HT was in excellent agreement with the published value of 0.1 $cm^{2}V^{-1}s^{-1}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.92-96
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• 2002

A silver indium sulfide $(AgInS_{2})$ epilayer was grown by the hot wall epitaxy method, which has not been reported in the literature. The grown $AgInS_{2}$ epilayer has found to be a chalcopyrite structure and evaluated to be high quality crystal. From the photocurrent measurement in the temperature range from 30 K to 300 K, the two peaks of A and B were only observed, whereas the three peaks of A, B, and C were seen in the PC spectrum of 10 K. These peaks are ascribed to the band-ta-band transition. The valence band splitting of $AgInS_{2}$ was investigated by means of the photocurrent measurement. The crystal field splitting, $\Delta_{cr}$, and the spin orbit splitting, $\Delta_{so.}$ have been obtained to be 0.150 eV and 0.009 eV at 10 K, respectively. And, the energy band gap at room temperature has been determined to be 1.868 eV. Also, the temperature dependence of the energy band gap, $E_{g}(T)$, was determined.

• Bulletin of the Korean Chemical Society
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• v.10 no.1
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• pp.8-12
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• 1989

The polycrystalline powder of (BaLa)(MgMo)$O_6$ has been prepared at $1350^{\circ}C$ in a nitrogen flowing atmosphere. The powder X-ray diffraction pattern indicates that (BaLa)(MgMo)$O_6$ has a cubic perovskite structure ($a_0$ = 8.019(3) $\AA)$ with 1:1 ordering or $Mg^{2+}$ and $Mo^{5+}$ in the oxide lattice. The infrared spectrum shows two strong absorption bands with their maxima at 600(${\nu}3$) and 365(${\nu}4$) cm-1, which are attributed to $2T_{1U}$, modes of molybdenum octahedra MoO6 in the crystal lattice. According to the magnetic susceptibility measurement, the compound shows a paramagnetic behavior which follows the Curie-Weiss law below room temperature with the effective magnetic moment 1.60(1){$\mu}B$, which is consistent with that of spin only value ($1.73{\mu}B$) for $Mo^{5+}$ ($4d^1$ electronic configuration). From the thermogravimetric and X-ray diffraction analyses, it has been found that (BaLa)(MgMo)$O_6$ decomposes gradually into $BaMoO_4$, $MoO_3$ and unidentified phases above $900^{\circ}C$ in an ambient atmosphere, absorbing about 0.25 mole $O_2$ per mole of Mo ion, which also supports that oxidation state of $Mo^{5+}$ in the (BaLa)(MgMo)$O_6$.

• Current Photovoltaic Research
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• v.7 no.3
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• pp.55-60
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• 2019

Polymer:nonfullerene solar cells with an inverted-type device structure were fabricated by employing the bulk heterojunction (BHJ) active layers, which are composed of poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophene-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T) and 3,9-bis(6-methyl-2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3-d']-s-indaceno[1,2-b:5,6-b']dithiophene (IT-M). The BHJ layers were formed on a pre-patterned indium-tin oxide (ITO)-coated glass substrate by spin-coating using the blend solutions of PBDB-T and IT-M. The solar cell performances were investigated with respect to the cell position on the ITO-glass substrates. In addition, the short-term shelf lifetime of solar cells was tested by storing the PBDB-T:IT-M solar cells in a glovebox filled with inert gas. The results showed that the performance of solar cells was relatively higher for the cells close to the center of substrates, which was maintained even after storage for 24 h. In particular, the PCE of PBDB-T:IT-M solar cells was marginally decreased after storage for 24 h owing to the slightly reduced fill factor, even though the open circuit voltage was unchanged after 24 h.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.3
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• pp.99-105
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• 2014

$LiCoO_2$ thin film have received attention as cathodes of thin-film microbatteries. In this study, $LiCoO_2$ thin films were synthesized on Au substrates by sol-gel spin coating method and electrochemical properties were investigated under annealing temperature and time. The phycochemical properties of $LiCoO_2$ thin film were investigated by X-ray diffraction, scaning electron microscopy and atomic force microscopy. The electrochemical properties were characterized using galvanostatic charging/discharging cycling tests. From X-ray diffraction, as-grown films annealed at $550^{\circ}C$ and $750^{\circ}C$ are presumed to be spinel structure and a single phase of the layered-rock-salt, respectively. The RMS roughness and grain size of the films which annealed at $750^{\circ}C$ has similar values for annealing time 10 and 30 min, while for annealing time 120 min surface roughness, grain size increase and pore appearance were observed. The first discharge capacity of $LiCoO_2$ thin films annealed at $750^{\circ}C$ for 10, 30 and 120 min is about 54.5, 56.8 and $51.87{\mu}Ah/cm^2{\mu}m$, respectively. Corresponding capacity retention at 50th cycle is 97.25, 76.69, 77.19%.

• Journal of the Korean Magnetics Society
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• v.27 no.3
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• pp.87-91
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• 2017

Carbon-encapsulated Ni and metal Ni nanoparticles were synthesized by levitational gas condensation (LGC). Methane ($CH_4$) gas was used to coat the surface of the Ni nanoparticles. The Ni particles had a core diameter of 10 nm, and were covered by 2~3 nm thin carbon layers with multi-shells structure.The low magnetization comparing with the Ni nanoparticles without carbon-shell results in the coexistence of nonmagnetic carbon and a large surface spin percentage with disordered magnetization orientation for the nanoparticles. Biginelli reactions in the presence of L-proline and Ni and carbon encapsulated Ni nanoparticles were carried out to change the ratio between stereoisomers. The obtained S-enantiomers for 3,4-dihydropyrimidine (DHPM) using catalysts of Ni, and Ni@C was an excess of about ${\Delta}{\sim}7.4%$ and ${\Delta}{\sim}19.6%$, respectively. The nanopowders were fully recovered using magnet to reuse as a catalyst. The Ni@C was shown at same yield to formation of 3,4-DHPM, though it was recycled for catalyst in the reaction.

• Journal of the Korean Chemical Society
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• v.45 no.3
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• pp.242-246
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• 2001

The quaternary thiophosphates, $A_2NiP_2S_6$ (A=Rb, Cs), have been synthesized with halide fluxes and structurally characterized by single-crystal X-ray diffraction technique. These compounds crystallize in the space group $C_{2h}^5-P2_1/n$ of the monoclinic system with two formula units in a cell of dimensions a=5.960(2), b=12.323(4), $c=7.491(3)\AA$, $\beta=97.05(3)^{\circ}$, and $V=546.0(3)\AA^3$ for Rb2NiP2S6 and a=5.957(4), b=12.696(7), $c=7.679(4)\AA$, $b=93.60(5)^{\circ}$, and $V=579.7(5)\AA^3$ for $Cs_2NiP_2S_6.$ These compounds are isostructural. The structure of $Cs_2NiP_2S_6$ is made up of one-dimensional $_\infty^1[NiP_2S_6^{2-}]$ chains along the a axis and these chains are isolated by $Cs^+$ ions. The Ni atom is octahedrally coordinated by six S atoms. These Ni$S_6$ octahedral units are linked by sharing three m-S atoms of the $[P_2S_6^{4-}]$ anions to form the infinite one-dimensional $_\infty^1[NiP_2S_6^{2-}]$ chain. For $Cs_2NiP_2S_6$, the magnetic susceptibility reveals an antiferromagnetic exchange interaction below 8K,which corresponds to the Neel temperature ($T_N$). Above $T_N$, this compound obeys Curie-Weiss law. The magnetic moment, C, and ${\theta}forCs_2NiP_2S_6$ are 2.77 B.M., 0.9593 K, and -19.02 K, respectively. The effective magnetic moment obtained from the magnetic data is agreed with the spin-only value of $Ni^{2+}d^8$(2.83 B.M.) system.

• Korean Journal of Crystallography
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• v.12 no.3
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• pp.127-136
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• 2001

A stoichiometric mixture of evaporating materials for ZnGa₂Se₄single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, ZnGa₂Se₄mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were 610℃ and 450℃, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of ZnGa₂Se₄single crystal thin films measured from Hall effect by von der Pauw method are 9.63×10/sup 17/㎤ and 296 ㎠/V·s at 293 K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the ZnGa₂Se₄single crystal thin film, we have found that the values of spin orbit splitting △so and the crystal field splitting Δcr were 251.9meV and 183.2 meV at 10 K, respectively. From the photoluminescence measurement on th ZnGa₂Se₄single crystal thin film, we observed free excition (Ex) existing only high quality crystal and neutral bound exiciton (A°, X) having very strong peak intensity. Then, the full-width-at-half-maximum (FWHM) and binding energy of neutral acceptor bound excition were 11 meV and 24.4 meV, respectivity. By Haynes rule, an activation energy of impurity was 122 meV.