• Transactions of the Korean hydrogen and new energy society
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• v.9 no.1
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• pp.25-30
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• 1998

4-probe resistivity measurement technique was used to study kinetics of hydrogen absorption on Pd film ($180{\AA}$ thick) in the ${\alpha}$ phase. Hydrogen gas was introduced to the activated Pd film. For very low hydrogen concentration the following rate law is valid in ${\alpha}$ phase very thin Pd film $$v=k\frac{1}{1+KX{_H}}PH{_2}-k^{\prime}\frac{KX{_H}{^2}}{1+KX{_H}}$$ which is similar to that of bulk. The activation energy of the forward reaction is 4.6kcal/mol H and of the backward reaction 8.4kcal/mol H, which yields the reaction enthalpy -3.8kcal/mol H in the temperature range between 25 and $40^{\circ}C$. The values of activation and enthalpy of thin film are rather smaller than that of bulk sample. This may be due to surface area difference between bulk and film.

• Archives of Pharmacal Research
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• v.24 no.2
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• pp.159-163
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• 2001

The accelerated stability of dimethoxy biphenyl monocarboxylate.HCl (DDB-S) was investigated in 6 mg/mL water solution in the pH ranging 2-10 and the temperature of $45-85^{\circ}C$. The observed rate of degradation followed first-order kinetics. The energy of activation for DDB-S degradation was calculated to be 14.1 and 16.5 $Kcal/mole$ at pH 5 and in distilled watery respectively. The degradation rate constant ($K_{25^{\circ}C}$) obtained by trending line analysis of Arrhenius plots for DDB-S was $5.3{\times}10^{-6}h^{-1}$. The times to degrade 10% ($t_{10}$) and 50% $t_{500}$) at $K_{25^{\circ}C}$ were 829 and 5,416 days, respectively. DDB-S exhibited the fastest degradation at pH 10 and the slowest rate at pH 5. In addition, at $K_{65^{\circ}C}$, degradation rate constants of DDB-S were 0.066, 0.059, 5.460, 32.171, and $1.4{\times}10^{-6}h^{-1}$ at pH 2, 5, 8, 10 and in distilled water, respectively. These observations indicated that the rate-pH profile of DDB-S showed general acid-base catalysis reaction in the range of pH 2-10.

• Proceedings of the PSK Conference
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• 2000.04a
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• pp.109.1-109.1
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• 2000

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.546-549
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• 1993

The correlation between electrical conduct ion and dielectric relaxation properties of copper ion conducting glasses is discussed. The glasses were prepared in the system $CuI-Cu_2S-Cu_2O-MoO_3$ using rapid quenching technique. These glasses have high ionic conductivities at room temperature in the range of $10^{circ}$[S/m], and the conductivities increase with increasing CuI content. The activation energies for conduction are 0.26-0.57 eV. The dielectric relaxation times are 1-10uS, and the activation energy for ion jumping are 0.18-0.41eV. It is shown that the tendency of conduction properties depending on composition of the glass is similar those of dilectric relaxation.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.221-224
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• 2002

Nucleophilic addition reactions of benzylamines (BA; $XC_6H_4CH_2NH_2$) to ethyl-${\alpha}$-cyanocinnamates (ECC;$YC_6H_4CH$=C(CN)COOEt) have been investigated in acetonitrile at $30.0^{\circ}C$. The rate is first order with respect to BA and ECC. The rate is slower than that expected from the additive effect of ${\sigma}^-$ or $R^-$ for the activating groups (CN and COOEt). Natural. bond orbital ${\pi}^{\ast}_{c=c}$ calculations show that the contribution of COOEt group may not be fully effective despite the coplanar molecular structure. The selectivity parameters including the cross-interaction constant (${\rho}_{xy}$ = -0.22) indicate that the addition occurs in a single step. The kinetic isotope effects ($k_H/k_D$=2.5-2.8) involving deuterated BA ($XC_6H_4CH_2ND_2$) nucleophiles and activation parameters (${\Delta}H^{\neq}=4{\sim}6\;kcal\;mol^{-1};{\Delta}S^{\neq}=-45{\sim}-52\;e.u.$) suggest a cyclic transition state in which N-$C_{\alpha}$ and H-$C_{\beta}$ bonds are formed concurrently.

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.6
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• pp.555-561
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• 2020

TWIK-related two-pore domain K⁺ channel-2 (TREK-2) has voltage-independent activity and shows additional activation by acidic intracellular pH (pH_i) via neutralizing the E³³² in the cytoplasmic C terminal (Ct). We reported opposite regulations of TREK-2 by phosphatidylinositol 4,5-bisphosphate (PIP₂) via the alkaline K³³⁰ and triple Arg residues (R^355-357); inhibition and activation, respectively. The G³³⁴ between them appeared critical because its mutation (G³³⁴A) endowed hTREK-2 with tonic activity, similar to the mutation of the inhibitory K³³⁰ (K³³⁰A). To further elucidate the role of putative bent conformation at G³³⁴, we compared the dual mutation forms, K³³⁰A/G³³⁴A and G³³⁴A/R^355-7A, showing higher and lower basal activity, respectively. The results suggested that the tonic activity of G³³⁴A owes to a dominant influence from R^355-7. Since there are additional triple Arg residues (R^377-9) distal to R^355-7, we also examined the triple mutant (G³³⁴A/R^355-7A/R^377-9A) that showed tonic inhibition same with G³³⁴A/R^355-7A. Despite the state of tonic inhibition, the activation by acidic pH_i was preserved in both G³³⁴A/R^355-7A and G³³⁴A/R^355-7A/R^377-9A, similar to the R^355-7A. Also, the inhibitory effect of ATP could be commonly demonstrated under the activation by acidic pH_i in R^355-7A, G³³⁴A/R^355-7A, and G³³⁴A/R^355-7A/R^377-9A. These results suggest that the putative bent conformation at G³³⁴ is important to set the tug-of-war between K³³⁰ and R^355-7 in the PIP₂-dependent regulation of TREK-2.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.8
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• pp.17-27
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• 2000

This paper presents deposition and characterization of hydrogenated microcrystalline silicon (${\mu}c$ -Si:H) films on low cost glass substrate by Hot Wire CVD(HWCVD). The HWCVD ${\mu}c$ -Si:H films had deposition rates ranging from 2${\AA}$/sec to 35${\AA}$/sec with the variations of preparation conditions, which was 10 times higher than that of the films obtained from the conventional PECVD method. From the Raman spectroscopy, the prepared silicon films were found to be composed of the mixture of crystalline and amorphous phases. The crystalline volume fraction and average crystallite size, obtained from the Raman To mode peak near 520cm$^{-1}$, were 37-63% and 6-10 nm, respectively. The conductivity activation energy($E_a$) of the ${\mu}c$ -Si:H films, representing the difference of conduction band and Fermi level in an intrinsic semiconductors, increased from 0.22eV to 0.68eV with increasing pressure from 30mTorr to 300mTorr. The increase of $E_a$ with pressure indicates that the deposited films have properties close to intrinsic semiconductors, which is also proved with low dark conductivity of the ${\mu}c$ -Si:H deposited at 300mTorr. The tungsten concentration incorporated into films was about $6{\times}10^{16}atoms/cm^3$ in the samples prepared at wire temperature of 1800$^{\circ}C$.

• Journal of the Korean Magnetic Resonance Society
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• v.11 no.2
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• pp.85-94
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• 2007

Vanilloid receptor I [transient receptor potential vanilloid subfamily member 1 (TRPV1), also known as VR1] is a non-selective cationic channel activated by noxious heat, vanilloids, and acid, thereby causing pain. VR1 possesses six transmembrane domain and N-and C-terminus cytosolic domains, and appears to be a homotetramer. We studied the structural properties of Cterminus of VR1 (VR1C) using CD and NMR spectroscopy. DPC micelles, with a zwitterionic surface, and SDS micelles, with a negatively charged surface, were used as a membrane mimetic model system. Both SDS and DPC micelles could increase the stability of helical structures and/or reduce the aggregation form of the VR1C. However, the structural changing mode of the VR1C induced by the SDS and DPC micelles was different. The changes according to the various pHs were also different in two micelles conditions. Because the net charges of the SDS and DPC micelles are negative and neutral, respectively, we anticipate that this difference might affect the structure of the VR1C by electrostatic interaction between the surface of the VR1C and phospholipids of the detergent micelles. Based on these similarity and dissimilarity of changing aspects of the VR1C, it is supposed that the VR1C probably has the real pI value near the pH 7. Generally, mild extracellular acidic pH ($6.5{\sim}6.8$) potentiates VRI channel activation by noxious heat and vanilloids, whereas acidic conditions directly activate the channel. The channel activation of the VRI might be related to the structural change of VR1C caused by pH (electrostatic interactions), especially near the pH 7. By measuring the $^1-^{15}N$ TROSY spectra of the VR1C, we could get more resolved and dispersed spectra at the low pH and/or detergent micelles conditions. We will try to do further NMR experiments in low pH with micelles conditions in order to get more information about the structure of VR1C.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.104-111
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• 2001

B-doped hydrogenated amorphous silicon carbide (a-SiC:H) thin films were prepared by plasma-enhanced chemical-vapor deposition in a gas mixture of $SiH_4, CH_4,\;and\; B_2H_6$. Physical and chemical properties of a-SiC:H films grown with varing the ratio of $B_2H_6/(SiH_4+CH_4)$ were characterized with various analysis methods including scanning electron microscopy (SEM), X-ray diffractometry (XRD), Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, secondary ion mass spectroscopy (SIMS), UV absorption CH_4spectroscopy and electrical conductivity measurements. With the B-doping concentration, the doping efficiency and the micro-crystallinity were decreased and the film became amorphous when $B_2H_6/(SiH_4{plus}CH_4)$ was over $5{\times}10^{-3}$. The addition of $B_2H_6$ gas during deposition decreased the H content in the film by lowering the quantity of Si-C-H bonds. Consequently, the optical band gap and the activation energy of a-SiC:H films were decreased with increasing the B-doping level.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.64.2-64.2
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• 2011

a-Si 박막 태양전지는 a-Si:H을 유리 기판 사이에 주입해 만드는 태양전지로, 뛰어난 적용성과 경제성을 지녔으나 c-Si 태양전지에 비해 낮은 변환 효율을 보이는 단점이 있다. 변환 효율을 높이기 위한 연구 방법으로는 a-Si 박막 태양전지 단일cell 제작 시 high Bandgap을 가지는 p-layer를 사용함으로 높은 Voc와 Jsc의 향상에 기여할 수 있는데, 이 때 p-layer의 defect 증가와 activation energy 증가도 동시에 일어나 변환 효율의 증가폭을 감소시킨다. 이를 보완하기 위해 본 실험에서는 p-layer에 기존의 p-a-Si:H를 사용함과 동시에 high Bandgap의 buffer layer를 p-layer와 i-layer 사이에 삽입함으로써 그 장점을 유지하고 높은 defect과 낮은 activation energy의 영향을 최소화하였다. ASA 시뮬레이션을 통해 a-Si:H보다 high Bandgap을 가지는 a-SiOx 박막을 사용하여 p-type buffer layer의 두께를 2nm, Bandgap 2.0eV, activation energy를 0.55eV로 설정하고, i-type buffer layer의 두께를 2nm, Bandgap 1.8eV로 설정하여 삽입하였을 때 박막 태양전지의 변환 효율 10.74%를 달성할 수 있었다. (Voc=904mV, Jsc=$17.48mA/cm^2$, FF=67.97).