• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.126-126
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• 2017

Using first principles calculations we unveil fundamental mechanism of hydrolysis reactions of two hazardous chemicals $PCl_3$ and $POCl_3$ with molecular water clusters nearby. It is found that the water molecules play a key role as a catalyst significantly lowing the activation barriers by transferring its protons to the reaction intermediates. Interestingly, torsional angles of molecular complexes at transition states are identified as a vital descriptor on the reaction rate. Analysis of charge distribution over the complexes further reinforces the finding with atomic level correlation between the torsional angle and variation of the orbital hybridization state of P in the complex. Electronic charge separation (or polarization) enhances thermodynamic stability of the activated complex at transition state and reduces the activation energy through hydrogen bonding network with water molecules nearby. Calculated potential energy surfaces (PES) for the hydrolysis reactions of $PCl_3$ and $POCl_3$ depict their two contrastingly different profiles of double- and triple-deep wells, respectively. It is ascribed to the unique double-bonding O=P in the $POCl_3$. Our results on the activation free energy show well agreements with previous experimental data within $7kcalmol^{-1}$ deviation.

• 대한화학회지
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• 제19권3호
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• pp.149-155
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• 1975

플라스틱 결정체인 피발산의 temperature-dependent wide-line NMR line width, second monent 및 spin-lattice relaxation times 의 결과는 이 결정체의 특이한 운동학적 성질 및 수소결합에 기인된 것으로 해석된다. 이 분자의 운동학적 성질은 $C_3-C_3'$ reorientation 및 self-diffusion 으로 구성 되었음을 확인했다. Wide-line NMR 연구결과는 또한 Pople-Karasz 융해설과 비교검토되었고, 이 이론과의 차이점은 피발산의 수소결합에 기인되었음을 알아냈다.

• Bulletin of the Korean Chemical Society
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• 제33권9호
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• pp.2907-2909
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• 2012

A disintegrin and metalloprotease with thrombospondin domains (ADAMTS) are a member of peptidase and involved in processing of von Willebrand factor as well as cleavage of aggrecan, versican, brevican and neurocan. Among 19 subfamilies of human ADAMTS, ADAMTS-4 is a zinc-binding metalloprotease and is a famous therapeutic target for arthritis. It has been reported that a flavonoid luteolin shows inhibitory activity against ADMATS-4. In this study, we verified that luteolin is a potent inhibitor of ADAMTS-4 and probed the molecular basis of its action. On the basis of a docking study, we proposed a binding model between luteolin and ADAMTS-4 in which 3',4'-dihydroxyl groups in luteolin formed hydrogen bonding with ADMATS-4 and these interactions are important for its inhibitory activity against ADAMTS-4.

• 한국산학기술학회논문지
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• 제11권5호
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• pp.1768-1772
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• 2010

분자내부 회합은 계면활성제계, 특히 콜로이드와 생체물질에 있어서 수소결합 중에서 매우 중요한 역할을 나타낸다. 미셀과 마이크로에멀젼을 형성하는 양친매성 계는 분자간 회합뿐만 아니라 분자내부 회합 때문에 매우 비이상적인 거동을 나타낸다. 본 연구의 목적은 계면활성제를 함유한 혼합물의 상거동을 계산하기 위하여, 내외부 분자 회합을 설명할 수 있는 수정된 베이츠만 통계역학이론과 결합된 유사화학반응 비무질도서 격자모델을 제시하는 것이다. 본 논문에서 제시된 격자모델은 알칸과 계면활성제의 실험결과를 매우 잘 설명할 수 있다.

• Carbon letters
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• 제16권3호
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• pp.192-197
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• 2015

In the present work, we propose a molecule (C₁₄H₁₄) that can be used as a building block of hexagonal diamond-type crystals and nanocrystals, including wurtzite structures. This molecule and its combined blocks are similar to diamondoid molecules that are used as building blocks of cubic diamond crystals and nanocrystals. The hexagonal part of this molecule is included in the C₁₂ central part of this molecule. This part can be repeated to increase the ratio of hexagonal to cubic diamond and other structures. The calculated energy gap of these molecules (called hereafter wurtzoids) shows the expected trend of gaps that are less than that of cubic diamondoid structures. The calculated binding energy per atom shows that wurtzoids are tighter structures than diamondoids. Distribution of angles and bonds manifest the main differences between hexagonal and cubic diamond-type structures. Charge transfer, infrared, nuclear magnetic resonance and ultraviolet-visible spectra are investigated to identify the main spectroscopic differences between hexagonal and cubic structures at the molecular and nanoscale. Natural bond orbital population analysis shows that the bonding of the present wurtzoids and diamondoids differs from ideal sp³ bonding. The bonding for carbon valence orbitals is in the range (2s^0.982p^3.213p^0.02)-(2s^0.942p^3.313p^0.02) for wurtzoid and (2s^0.932p^3.293p^0.01)-(2s^0.992p^3.443p^0.01) for diamantane.

• 대한화학회지
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• 제18권2호
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• pp.126-131
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• 1974

비수용성 긴고리 지방족 아민인$(n-C_8H_{17})_3N$과 $(n-C_8H_{17})_3NCH_3Cl$을 사용하여 산도가 틀린 텅그스텐산수용액(pH=2, 4, 6)으로 부터 용매추출법에 의하여 유기용매에 녹는 다중텅그스텐산아민염을 제조하는데 성공하였다. 제조된 텅그스텐산 아민염의 분자량을 벤젠용매에서 더미스트를 이용한 감도 1/$4000^{\circ}C$의 훼트스톤 브리지를 사용하여 측정할 수 있었다. 분자량 측정결과와 화학분석 및 적외선 스펙트럼으로 부터 pH=2, 4에서 생긴 아민염은 메타텅그스텐산염, pH=6에서 생긴 아민염은 파라텅그스텐산염이 아니고 미지의 새로운 다중텅고스텐산염임을 알 수 있었다.

• Composites Research
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• 제35권2호
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• pp.86-92
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• 2022

본 연구에서는 접착제를 구성하는 분자 결합 구조의 차이가 열가소성 복합재의 계면 특성에 미치는 영향을 판단하기 위해 진행되었다. 고온 오븐 접합 공정을 이용하여 carbonfiber/polyetherketoneketone(CF/PEKK) 열가소성 복합재료를 융합 접합, polyetheretherketone(PEEK), polyetherimide(PEI) 접착제 접합하였다. 그리고 lap 전단 강도 시험과 디지털 광학 현미경과 주사 전자 현미경을 이용한 파단면 분석, FTIR 분석을 수행하였다. 그 결과, 접착제 접합은 CF/PEKK와 접착제를 구성하는 주요 결합기인 에테르기, 케톤기, 이미드기의 결합이 증가한 인터페이즈를 형성하여 접착 강도를 강화시켰다. 그리고, 에테르기와 케톤기를 더 많이 함유한 PEEK를 사용하는 것이 더 강한 결합력을 갖는 인터페이즈를 형성하여, 복합재의 접착 강도를 향상시켰다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.139-139
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• 2012

With angle resolved photoemission spectroscopy (ARPES), the surface electronic band structures of Pt3Co (111) and Pt3Ni (111) single crystals are investigated, which allow to study the bonding interaction between chemically absorbed atomic oxygen and its surfaces. The d-band electrons of subsurface TM are separated from the direct chemical bonding with atomic oxygen. That is, the TM does not contribute to direct chemical bonding with oxygen. From the density functional theory (DFT) calculations, it is identified that the main origin of improved oxygen absorption property, i.e. softening of Pt-O bonding, is due to the suppression of Pt surface-states which is generated from change of interlayer potential, i.e. charge polarization, between Pt-top and TM-subsurface. Our results point out the critical roles of subsurface TM in modifying surface electronic structures, which in turn can be utilized to tune surface chemical properties.

• 접착 및 계면
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• 제13권1호
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• pp.1-8
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• 2012

EPDM에 카르복시산을 포함하는 아크릴 단량체인 methacrylic acid (MA)가 도입된 grafted EPDM을 합성하여 MA의 grafting ratio가 탄성체의 물성과 다른 고무와의 접착특성에 미치는 영향을 연구하였다. Grafted EPDM의 storage modulus는 특정온도까지는 sulfur로 가교한 EPDM vulcanizate보다 높게 유지되다가 온도가 더 높아지면 2차 결합력이 약해지면서 급격하게 감소되는 것이 관찰되었다. EPDM에 수소결합을 유도할 수 있는 반응기를 도입했을 때 grafted EPDM 분자들 간의 aggregate 형성과 그라프트된 MA의 결정성으로 인해 우수한 기계적 물성을 나타내었다. EPDM 자체는 극성이 낮고 다른 종류의 고무와 분자간 결합력이 약해서 접착이 제대로 이루어지지 않았으며 그라프트된 MA의 함량이 증가할수록 접착강도가 더 높아졌으며 MA의 grafting ratio가 10% 이상일 때에는 접착평가 시 고무시편이 부분적으로 파괴될 정도로 접착력이 우수하였다.

• 통합자연과학논문집
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• 제3권4호
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• pp.231-236
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• 2010

Partial charge is an important and fundamental concept which can explain many aspects of chemistry. Since a molecule can be regarded as neclei surrounded by electron cloud, there is no way to define a partial charge accurately. Nevertheless, there have been many attempts to define these seemingly impossible parameters, since they would facilitate the understanding of molecular properties such as molecular dipole moment, solvation, hydrogen bonding, molecular spectroscopy, chemical reaction, etc. Common methods are based on the charge equalization, orbital occupancy, charge density, and electric multipole moments, and electrostatic potential fitting. Methods based on the charge equalization using electronegativity are very fast, and therefore they have been used to study many compounds. Methods to subdivide orbital occupancy using basis set conversion, relies on the notion that molecular orbitals are composed of atomic orbitals. The main idea is to reduce overlap integral between two nuclei using converted orthogonal basis sets. Using some quantum mechanical observables like electrostatic potential or charge multipole moments. Using potential grids obtained from wavefunction, partial charges can be fitted. these charges are most useful to describe intermolecular electrostatic interactions. Methods to using dipole moment and its derivatives, seems to be sensitive the level of theory, Dividing electron density using density gradient being the most rigorous theoretically among various schemes, bears best potential to describe the charge the most adequately in the future.