• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2000.05a
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• pp.98-98
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• 2000

• Elastomers and Composites
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• v.50 no.3
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• pp.210-216
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• 2015

Polyurethane modified silicone (PUMS) was synthesized from various molecular weights of polydimethylsiloxane (PDMS 2000, PDMS 6000, PDMS 20000), polypropyleneglycol with molecular weight of 3000 g/mol (PPG 3000) and 2,4-toluenediisocyanate (TDI) under tin catalyst. Their structures were confirmed by the measurement of FT-IR and $^1H-NMR$, and the thermal properties were studied from DSC and TGA. Glass transition temperature of PUMS exhibited exothermic peak at $-63{\sim}-69^{\circ}C$, and residual weight was 19~35% at $800^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1317-1320
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• 2012

Well-defined solid-state microcrystalline structures from bispyridyl Zn-porphyrin have been successfully synthesized. The coordinative interactions between pyridine and Zn are main responsible for this translation of porphyrin molecular building blocks to crystalline microscopic objects. The hexagonal plates are obtained from acetonitrile and rhombus plates are grown from toluene solution. With a simple manipulation during the microcrystal growth, such as growth temperature and time, the morphologies can be controlled by adopting different molecular packing. Consequently, morphologies of microcrystals have been diversified.

• Genomics & Informatics
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• v.7 no.4
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• pp.212-216
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• 2009

WebChemDB is an integrated chemical database retrieval system that provides access to over 8 million publicly available chemical structures, including related information on their biological activities and direct links to other public chemical resources, such as PubChem, ChEBI, and DrugBank. The data are publicly available over the web, using two-dimensional (2D) and three-dimensional (3D) structure retrieval systems with various filters and molecular descriptors. The web services API also provides researchers with functionalities to programmatically manipulate, search, and analyze the data.

• Macromolecular Research
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• v.8 no.2
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• pp.53-58
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• 2000

Stabilities and structures of resorcinol formaldehyde resins (RF resins) and their dependence on solvent were studied by molecular mechanics and molecular dynamics. Dimers to decamers of the RF resins in the conditions of dielectric constant = 1.00, 21.01, 36.64, and 80.10 were calculated. The average distance between oxygen atoms in 1-hydroxyl groups of adjacent resorcinols of the resins became longer with increased dielectric constant of the environment. The number of intramolecular hydrogen bonds of the resins decreased by increasing the dielectric constant of the environment. The RF resin structure on the surface of fabric or steel cord was explained based on the present calculation.

• Bulletin of the Korean Chemical Society
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• v.22 no.4
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• pp.388-394
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• 2001

Quantitative Structure-Activity Relationship (QSAR) have been established of 57 fluorovinyloxyacetamides compounds to correlate and predict EC50 values. Genetic algorithm (GA) and multiple linear regression analysis were used to select the descriptors and to generate the equations that relate the structural features to the biological activities. This equation consists of three descriptors calculated from the molecular structures with molecular mechanics and quantum-chemical methods. The results of MLR and GA show that dipole moment of z-axis, radius of gyration and logP play an important role in growth inhibition of barnyard grass.

• Journal of Magnetics
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• v.10 no.3
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• pp.108-112
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• 2005

GaAs nanowires were grown on GaAs (111)B substrates in a gas source molecular beam epitaxy system, using self-assembled Au particles with diameters between 25 and 200 nm as the catalytic agents. The growth rate and structure of the nanowires were investigated for substrate temperatures between 500 and $600^{\circ}C$ to study the mass transport mechanisms that drive the growth of these crystals. The possibilities for fabrication of novel magnetic nanostructures by suitable choice of growth conditions are discussed.

• Applied Science and Convergence Technology
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• v.23 no.6
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• pp.317-327
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• 2014

In order to develop nano-devices with much lower power consumption for beyond-CMOS applications, the fundamental understanding and precise control of the electronic properties of ultrathin transition metal oxide (TMO) films are strongly required. The metal-insulator transition (MIT) is not only an important issue in solid state physics, but also a useful phenomenon for device applications like switching or memory devices. For potential use in such application, the electronic structures of MIT, observed for TMO nano-structures, have been investigated using a synchrotron radiation angle-resolved photoelectron spectroscopy system combined with a laser molecular beam epitaxy chamber and a scanning photoelectron microscopy system with 70 nm spatial resolution. In this review article, electronic structures revealed by soft X-ray nano-spectroscopy are presented for i) polarity-dependent MIT and thickness-dependent MIT of TMO ultrathin films of $LaAlO_3/SrTiO_3$ and $SrVO_3/SrTiO_3$, respectively, and ii) electric field-induced MIT of TMO nano-structures showing resistance switching behaviors due to interfacial redox reactions and/or filamentary path formation. These electronic structures have been successfully correlated with the electrical properties of nano-structured films and nano-devices.

• Journal of the Korean Magnetic Resonance Society
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• v.19 no.1
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• pp.1-10
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• 2015

Refinements with atomistic molecular dynamics (MD) simulation have contributed to improving the qualities of NMR structures. In most cases, the calculations with atomistic MD simulation for NMR structures employ generalized-Born implicit solvent model (GBIS) to take into accounts solvation effects. Developments in algorithms and computational capacities have ameliorated GBIS to approximate solvation effects that explicit solvents bring about. However, the quantitative comparison of NMR structures in the latest GBIS and explicit solvents is lacking. In this study, we report the direct comparison of NMR structures that atomistic MD simulation coupled with GBIS and water molecules refined. Two model proteins, GB1 and ubiquitin, were recalculated with experimental distance and torsion angle restraints, under a series of simulated annealing time steps. Whereas the root mean square deviations of the resulting structures were apparently similar, AMBER energies, the most favored regions in Ramachandran plot, and MolProbity clash scores witnessed that GBIS-refined structures had the better geometries. The outperformance by GBIS was distinct in the structure calculations with sparse experimental restraints. We show that the superiority stemmed, at least in parts, from the inclusion of all the pairs of non-bonded interactions. The shorter computational times with GBIS than those for explicit solvents makes GBIS a powerful method for improving structural qualities particularly under the conditions that experimental restraints are insufficient. We also propose a method to separate the native-like folds from non-violating diverged structures.

• Journal of Life Science
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• v.8 no.2
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• pp.226-226
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• 1998

Discovery of molecular chaperone has stimulate cell biologists and thus made it possible to re-examine the processes whereby proteins achieve and maintain their functional conformations within living cells. the term ‘Molecular chaperone’ was first coined to describe one particular protein involved in the assembly of nucleosomes, but the term has now been extended to describe the function of a wide variety of proteins that assist protein transport across membranes, folding of nascent polypeptide, the assembly and disassembly of oligomeric structures, and the recovery or removal of proteins damaged by various environmental stresses including heat shock. Progress of molecular chaperone research is still limited by the lack of 3-dimensional structural information and detailed interacts with taget proteins in the cell. However, several laboratories around the world are attempting to extend our knowledge on the functions of molecular chaperone, and such efforts seem justified to finally provide the answers to the most burning questions shortly.