• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3787-3789
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• 2013

In this study, the silicone thermal curing degree of the silicone-encapsulated quantum dot light emission diode was measured using the various types of chemical ligands around quantum dot. It was confirmed that the trioctyl phosphin oxide (TOPO) ligand around the quantum dot was responsible for dispersion of the quantum dot in silicone encapsulant and decline of the thermal curing degree of the silicone encapsulant. Also, it was confirmed that the thermal curing degree of silicone encapsulants containing the steric acid (SA) and the dodecanoic acid (DA) ligands were higher than the one of TOPO ligand.

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1733-1736
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• 2011

• Bulletin of the Korean Chemical Society
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• 제24권6호
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• pp.691-694
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• 2003

We report a quantum wavepacket study on the characteristic bimodal translational energy distribution of photostimulated desorbed Xe from an oxidized silicon (001) surface observed by Watanabe and Matsumoto, Faraday Discuss. 117 (2000) 203. We have simulated the theoretical translational energy distributions based on wavepacket calculations with a sudden transition and averaging model to reproduce the experiment. We discuss the desorption mechanism and suggest a very strong position dependence of the deexcitation processes for Xe/oxidized Si(001).

• Journal of Microbiology and Biotechnology
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• 제17권7호
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• pp.1098-1105
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• 2007

Quantum mechanical and molecular dynamics simulation analysis has been performed on the model system for CALB (Candida antarctica lipase B) with esters to study the reaction mechanism and conformational preference of catalytic hydrolysis and the esterification reaction. Using quantum mechanical analysis, the ping-pong bi-bi mechanism was applied and energies and 3-dimensional binding configurations of the whole reaction pathways were calculated. Further molecular dynamics simulation analysis was performed on the basis of the transition state obtained from quantum mechanical study to observe the effect of structures of the substrates. Calculation results using substrates of different chain length and chiral configurations were compared for conformational preference. The calculated results showed very small influence on chain length, whereas chiral conformation showed big differences. Calculated results from molecular modeling studies have been compared qualitatively with the experimental data using racemic mixtures of (${\pm}$)-cis-4-acetamido-cyclopent-2-ene-1-ethyl acetate as substrates.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.197-197
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• 2016

Quantum dot nanocrystals(QDs) have been emerged as next generation materials in the field of energy harvesting, sensor, and light emitting because of their compatibility with solution process and controllable energy band gap. Especially, characteristics of color tuning and color purity make it possible for QDs to be used photoluminescence materials. Photoluminescence devices with QDs have been researched for a long time. Photoluminescence quantum yield(PL QY) is important factor that defines the performance of Photoluminescence devices. One of the ways to achieve better PL QY is ligand modification. If ligands are changed to proper electron donating group, electrons can be confined in the core which results in enhancement of PL QY. Because of the reason, short ligands are preferred for enhancing PL QY. Thiophenol-based ligands are shorter than typical alkyl chain ligands. In this study, the effect of thiophenol-based ligands with different functional groups are investigated. Four different types of thiophenol-based organic materials are used as organic capping ligand. QDs with bare thiophenol and fluorothiophenol show better quantum yield compared to oleic acid.

• 한국융합학회논문지
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• 제6권2호
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• pp.49-55
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• 2015

양자점 기술은 나노연구 관점에서 벌크 재료에 대한 보완적 응용과 고유한 특성을 활용한 응용의 폭이 넓어 융합기술로서 의미가 크다. 양자점 기술의 발전과 더불어 기술성, 사업성, 시장성에 기반한 현황 분석이 매우 중요하고, 이에 본 연구는 특허, 논문, 시장 및 산업, 국가 R&D 과제 정보를 활용한 4P 분석 방법을 적용하여 양자점 연구의 동향을 파악하고자 한다. 연구의 결과물은 양자점 연구의 방향 설정, 전략 수립에 활용될 수 있는 기초 정보를 제공한다. 특히 특허와 논문 분석을 통해 양자점 연구 성과를 파악하고, 급격한 성장세를 보이는 응용 분야와 사업화를 견인하고 있는 응용 분야를 도출하였다. 또한 선진 연구와 국내 연구 동향을 비교하여 국내 양자점 연구 현황을 진단할 수 있는 초석을 제공하였다는 점에서 본 연구가 의미를 갖는다.

• 한국재료학회지
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• 제31권9호
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• pp.496-501
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• 2021

Metal halide perovskite nanocrystals, due to their high absorption coefficient, high diffusion length, and photoluminescence quantum yield, have received significant attention in the fields of optoelectronic applications such as highly efficient photovoltaic cells and narrow-line-width light emitting diodes. Their energy band structure can be controlled via chemical exchange of the halide anion or monovalent cations in the perovskite nanocrystals. Recently, it has been demonstrated that chemical exfoliation of the halide perovskite crystal structure can be achieved by addition of organic ligands such as n-octylamine during the synthetic process. In this study, we systematically investigated the quantum confinement effect of methylammonium lead bromide (CH₃NH₃PbBr₃, MAPbBr₃) nanocrystals by precise control of the crystal thickness via chemical exfoliation using n-octylammonium bromide (OABr). We found that the crystalline thickness consistently decreases with increasing amounts of OABr, which has a larger ionic radius than that of CH₃NH₃⁺ ions. In particular, a significant quantum confinement effect is observed when the amounts of OABr are higher than 60 %, which exhibited a blue-shifted PL emission (~ 100 nm) as well as an increase of energy bandgap (~ 1.53 eV).

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.571-574
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• 2012

In present study, CdSe quantum dots (QDs) were prepared with a novel but simple, effective and exercisable method. Nine different types of carbohydrate molecules were used to modify CdSe QDs. D-mannose (Man)-coated quantum dots were prepared for labeling human hepatoma (HepG2) cells, because of the high expression of mannose receptor (MR) on HepG2 cells. The uptake characteristics of CdSe QDs-Man were investigated in HepG2 cells. The absorption rate result of MTT assay in 48 h suggested the extremely low cytotoxicity of CdSe QDs-Man. The presence of quantum dots was confirmed with fluorescence microscopy. These results were encouraging regarding the application of QDs molecules for early detection of HepG2 cells.

• BMB Reports
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• 제33권1호
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• pp.37-42
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• 2000

Based on the study by Leatham and Stabmann concerned with the rates (v) of amines and phenolic compounds oxidation catalyzed by laccase of basidiomycete Lentinus edodes (Berk.) Sing., as well as on the results of semiempirical quantum chemical computations using the PM3 method, the linear correlations of v and lnv values with first vertical ionization potentials of the substrates molecules and radicals derived from them, spin densities on N and O atoms of the above radicals, and with the radicals reorganization energies have been found.

• 약학회지
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• 제33권2호
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• pp.87-100
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• 1989

Salicylic acids as anti-inflammatory agents were analyzed by ab initio, quantum chemical methods to study the possible modes of binding to the receptor. As the result of multiple regression analysis of reactivity indices and interpretation of normalized frontier orbital charges of drugs, potency seems to be related to energy of HOMO and LUMO at the 5 position of benzene ring, and in the 5-phenyl substituted case, the para position of substituting ring is important. The binding occurs first at the positive site of its receptor. The charge density exhibited by the frontier orbitals suggests that charge moves from receptor site to carboxyl group. The electrostatic orientation effect makes an important contribution to the binding of the active molecules to their receptors. Also the electrostatic potential model may be able to rationalize the source of activity or inactivity of the drugs under investigation.