• 한국산학기술학회논문지
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• 제8권5호
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• pp.1013-1019
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• 2007

[ $150^{\circ}C$ ]의 저온에서 플라즈마 화학기상증착 (PECVD) 방법으로 비정질 규소 및 질화규소 박막을 성막 하였다. 비정질 질화규소 박막은 소스 가스의 수소 분율을 증가시킴에 따라 굴절률이 1.9에 접근하고 질소-수소 결합이 주도적이 되어 고온성막한 박막에 버금가는 특성을 보였다. 비정질 규소 박막은 소스 가스의 수소 분율을 높임에 따라 굴절률과 광학적 금지대역의 크기가 고온 성막된 박막의 값인 4.2와 1.8 eV에 근접한 값을 가지게 되었으며, $[Si-H]/([Si-H]+[Si-H_2])$의 값이 증가하여 양질의 박막특성을 얻을 수 있었다. RF 전력 및 증착 압력에 대해서 낮은 전력과 작은 압력에서 양질의 박막을 얻을 수 있었으며, 박막 특성은 RF 전력 보다는 증착 압력의 변화에 대해서 좀더 큰 의존성을 보였다. 박막트랜지스터 제작에 적용 가능한 양질의 비정질 규소 및 질화규소 박막을 저온에서 얻기 위해서는 소스 가스의 수소 분율을 높게 하는 것이 중요한 공통 인자로 파악되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.107-107
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• 2011

Supramolecular structures of anthraquinone molecules on a metallic surface are studied using scanning tunneling microscope (STM) under ultrahigh-vacuum conditions. When we deposited anthraquinone molecules on Au(111) substrate, the molecules formed three different phases (Chevron type, tetragon type and disordered type) on the surface. Based on our STM measurements, we proposed models for the observed molecular structures. Chevrons are consisted of several molecular chains, which make well-ordered two-dimensional islands by some weak interrow interactions and we could observe tetragon structures which make array of (111) metallic surface. each molecular rows in the chevrons are stabilized by two parallel O-H hydrogen bonds and disordered structures are observed 1-dimensional phase with hydrogen bond. First-principles calculations based on density functional theory are performed to reproduce the proposed models. Distances and energy gains for each intermolecular bond are estimated. In this presentation, we explain possible origins of these molecular structures in terms of hydrogen bonds, Van der Waals interactions and molecule-substrate interactions.

• 한국전기전자재료학회논문지
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• 제18권11호
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• pp.996-1000
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• 2005

Experimental results are presented for the degradation of 3 nm-thick gate oxide $(SiO_2)$ under both Negative-bias Temperature Instability (NBTI) and Hot-carrier-induced (HCI) stresses using P and NMOSFETS, The devices are annealed with hydrogen or deuterium gas at high-pressure $(1\~5\;atm.)$ to introduce higher concentration in the gate oxide. Both interface trap and oxide bulk trap are found to dominate the reliability of gate oxide during electrical stress. The degradation mechanism depends on the condition of electrical stress that could change the location of damage area in the gate oxide. It was found the trap generation in the gate oxide film is mainly related to the breakage of Si-H bonds in the interface or the bulk area. We suggest that deuterium bonds in $SiO_2$ film are effective in suppressing the generation of traps related to the energetic hot carriers.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.265-265
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• 2013

We have investigated the influences of dangling bonds generated by alpha particle irradiation on friction and adhesion properties of graphene. Single layer of graphene grown with chemical vapor deposition on copper foil was irradiated by the alpha beam with the average energy of 3.04 MeV and the irradiation dosing between $1{\times}10^{14}$ and $1{\times}10^{15}$/$cm^3$. Raman spectroscopic showed that the ${\pi}$ electron states below Fermi level arises and the $I_D$/$I_G$ increases as increasing the dosing of alpha particle irradiation. The core level X-ray photoelectron (XPS) revealed that these defects represent the creation of various carbon-related defects and dangling bond. The nanoscale tribological properties were investigated with atomic force microscopy in ultrahigh vacuum. The friction appeared to increase remarkably as increasing the amount of dosing, indicating that the dangling bonds on graphene layers enhances the energy dissipations in friction. This trend can be explained by the additional channel of energy dissipation by dangling bond or O- and H- terminated clusters created by alpha particle irradiation.

• Structural Engineering and Mechanics
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• 제73권5호
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• pp.585-598
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• 2020

We develop design model within which nucleation and propagation of crack in a fibrous composite is described. It is assumed that under loading, crack initiation and fracture of material happens in the composite. The problem of equilibrium of a composite with embryonic crack is reduced to the solution of the system of nonlinear singular integral equations with the Cauchy type kernel. Normal and tangential forces in the crack nucleation zone are determined from the solution of this system of equations. The crack appearance conditions in the composite are formed with regard to criterion of ultimate stretching of the material's bonds. We study the case when near the fiber, the binder has several arbitrary arranged rectilinear prefracture zones and a crack with interfacial bonds. The proposed computational model allows one to obtain the size and location of the zones of damages (prefracture zones) depending on geometric and mechanical characteristics of the fibrous composite and applied external load. Based on the suggested design model that takes into account the existence of damages (the zones of weakened interparticle bonds of the material) and cracks with end zones in the composite, we worked out a method for calculating the parameters of the composite, at which crack nucleation and crack growth occurs.

• Bulletin of the Korean Chemical Society
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• 제32권4호
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• pp.1228-1230
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• 2011

A new amine receptor 2 utilizing anthracene and nitrophenyl group as signaling group was designed and synthesized. The receptor 2 only utilizes four amine N-H's and 9-anthracenyl hydrogen to bind anions. The receptor 2 can bind anions through hydrogen bonds with a selectivity of $CH_3CO_2^-$ > $H_2PO_4^-$ > $F^-$ > $C_6H_5CO_2^-$ > $Cl^-$ in highly polar solvent such as DMSO without protonation of amine.

• Journal of Photoscience
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• 제12권3호
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• pp.185-186
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• 2005

The electronic structure of photoskinsensitizing psoralens has been investigated by the ab initio calculations. The photocycloaddition reaction of 8-methoxypsoralen with thymine is studied as a model for the photosensitizing reaction of psoralen with DNA bases. The photocycloadduct was inferred to be a C4-cycloaddition product with the stereochemistry of Syn, H-H, Syn, H-T formed through [2+2] addition reaction between the 3,4-double bonds of 8-methoxypsoralen and 5,6-double bond of thymine base.

• Elastomers and Composites
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• 제52권3호
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• pp.180-186
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• 2017

In this work, the effect of low-temperature dehydration of a poly(styrene-co-styrenesulfonic acid) (PSSA) membrane was investigated by differential scanning calorimetry, fourier transform infrared spectroscopy (FT-IR), electron magnetic resonancespectroscopy (EMR), and $^1H$- and $^{13}C$ solid-state nuclear magnetic resonance spectroscopy. These analyses were performed at room temperature for powdered PSSA specimens with and without dehydration and the following key observations were made. First, FT-IR analysis showed that low-temperature dehydration not only transformed the [${SO_3}^-{\cdots}H^+$] ionic pair in the non-hydrated PSSA to an $SO_3H$ group, but also induced the formation of -C=C- double bonds in the dehydrated PSSA. Second, the ${-SO_3}^{\bullet}$ radical was unambiguously identified by EMR spectroscopy. Third, H-abstraction was detected by $^1H$ magic-angle spinning spectroscopy. Finally, an unexpected color shift from white for the non-hydrated PSSA to a yellowish brown for the dehydrated sample was observed. In order to explain these experimental results, it was proposed that the formation of the intermediate hydrogen ($H^{\bullet}$) or hydroxyl radical ($HO^{\bullet}$) species was initiated by the dehydration process. The sespecies attacked the $SO_3H$ group and the tertiary proton at the ${\alpha}-carbon$, resulting in the formation of $-SO^{\bullet}$ radicals and -C=C- double bonds, which correlated with the color shift in the dehydrated PSSA sample. The semechanisms are useful for understanding the simultaneous loss of an aromatic ring and -SO- groups in the PSSA fuel cell membrane.

• 한국결정학회지
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• 제2권1호
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• pp.12-16
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• 1991

p-dimethylaminobenzaldehyde 4-(p-ethoxyphenyl) thiosemicarbazone, C18H22N4OS의, 단위포상수는 단사정계 a=11.802(2), b=31.962(2), c=9.829(2)A, β=100.12(1)˚, V=3694.8A3이며 F(000)=1472, Mr=342.47, 공간군은 P2₁/c, Z=8, Dx=1.246 Mg m-3, Dm=1.17Mg m-3, μ=0.15mm-1이다. T=294 K에서 Mo Ka(λ=0.71073 A)을 사용하여 최종 R값은 0.0856이다. 비대칭단위내의 두개 분자간의 구조상의 큰차이는 C(9)-N(1)-C(6)-C(7)의 비틀림각이 각각 58.8(8)˚와 1(1)˚인것으로, 각 분자는 길이가 각각 2.613(7)과 2.566(7) A인 N(1)-H(10)'N(3) 분자내 수고결합을 하고 있으며 각 분자는 N(2)원자를 정점으로 하여 V-모양을 하고 있다. 독립적인 두 분자는 두개의 분자간 수소 결합 N(2)-H(11)'S'=3.367(5) A과 N(2')-H(11')'S=3.421(4)A으로 연결되어 이중체(dimer)를 형성하고 있으며 그 이중체들은 van der Waals력으로 결합되어 있다.

• Bulletin of the Korean Chemical Society
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• 제29권9호
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• pp.1717-1722
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• 2008

The 70 kDa heat-shock protein (Hsp70) involved in various cellular functions, such as protein folding, translocation and degradation, regulates apoptosis in cancer cells. Recently, it has been reported that the green tea flavonoid (−)-epigallocatechin 3-gallate (EGCG) induces apoptosis in numerous cancer cell lines and could inhibit the anti-apoptotic effect of human Hsp70 ATPase domain (hATPase). In the present study, docking model between EGCG and hATPase was determined using automated docking study. Epi-gallo moiety in EGCG participated in hydrogen bonds with side chain of K71 and T204, and has metal chelating interaction with hATPase. Hydroxyl group of catechin moiety also participated in metal chelating hydrogen bond. Gallate moiety had two hydrogen bondings with side chains of E268 and K271, and hydrophobic interaction with Y15. Based on this docking model, we determined two pharmacophore maps consisted of six or seven features, including three or four hydrogen bonding acceptors, two hydrogen bonding donors, and one lipophilic. We searched a flavonoid database including 23 naturally occurring flavonoids and 10 polyphenolic flavonoids with two maps, and myricetin and GC were hit by map I. Three hydroxyl groups of B-ring in myricetin and gallo moiety of GC formed important hydrogen bonds with hATPase. 7-OH of A-ring in myricetin and OH group of catechin moiety in GC are hydrogen bond donors similar to gallate moiety in EGCG. From these results, it can be proposed that myricetin and GC can be potent inhibitors of hATPase. This study will be helpful to understand the mechanism of inhibition of hATPase by EGCG and give insights to develop potent inhibitors of hATPase.