Nam-Soo Lee

Soonchunhyang University Hospital

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Sun-Kyung Park

Chungbuk National University

Choongkeun Lee

Yonsei University

Chang‐Ho Kim

Kyungpook National University

Kyung-Chul Min

Korea Basic Science Institute

Yong-Bok Lee

Korea Institute of Science and Technology

Chang Suk Kim

Kongju National University

Tae‐Ho Kim

Korea Electric Power Corporation (South Korea)

Dong-Hoon Choi

Hanyang University

Dong Won Kim

Korea Advanced Institute of Science and Technology

Haiil Ryu

Kongju National University

Cooperative Institutions

Chungbuk National University

Seoul National University

Government of the Republic of Korea

Korea University

Korea Research Institute of Chemical Technology

Catholic University of Korea

Korea Advanced Institute of Science and Technology

Sungkyunkwan University

Yonsei University

Hongik University

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Vibrational Analysis of Azacrown Ether Complex with Li Metal Cation

Bulletin of the Korean Chemical Society (2010)

Kyung-Chul Min Sun-Kyung Park Choongkeun Lee Chang-Suk Kim Nam-Soo Lee

$Li^+$ ion complex of azacrown ether with restricted motion of freedom and pseudo-bilateral symmetry was studied by infrared spectroscopy, which has shown simplified and broadened vibrational features. The C=O and N-H stretching bands, in particular, shows anomalous broadening nearly ${\sim}50\;cm^{-1}$. The density functional calculation at the level of BP86/6-31+$G^{**}$ shows that $Li^+$ ion is trapped and rather free to move around inside the cavity, as much as about $0.70\;{\AA}$. Through the relocation of $Li^+$ ion inside the cavity, the conformational changes would occur rapidly in its symmetry $C_1\;{\rightleftarrows}\;C_2\;{\rightleftarrows}\;C_1$$. The potential barrier was obtained to be merely ~2.2 kJ/mol for $C_1\;{\rightarrow}\;C_2$. During this conformational alteration, the amide backbone twists concurrently its dihedral angle side to side about up to ${\pm}3$ degree. Selected vibrational modes were interpreted in terms of the force constant variations of local symmetry coordinates between conformations in the framework of $C_1\;{\rightleftarrows}\;C_2\;{\rightleftarrows}\;C_1$.

Dihedral angle

Local symmetry

Amide

Side chain

10.5012/bkcs.2010.31.11.3385

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Vibrational Analysis of Ferrocyanide Complex Ion Based on Density Functional Force Field

Bulletin of the Korean Chemical Society (2002)

Sun-Kyung Park Choong-Keun Lee Sang Ho Lee Nam-Soo Lee

Vibrational properties of ferrocyanide complex ion, $[Fe(CN)_6]^{4-}$ , have been studied based on the force constants obtained from the density functional calculations at B3LYP/$6-31G^{\ast\ast}$ level by means of the normal mode analysis using new bond angle and linear angle internal coordinates recently developed. Vibrations of ferrocyanide were manipulated by twenty-three symmetry force constants. The angled bending deformations of C-Fe-C, the linear bending deformations of Fe-C${\equiv}$N and the stretching vibrations of Fe-C have been quantitatively assigned to the calculated frequencies. The force constants in the internal coordinates employed in the modified Urey-Bradley type potential were evaluated on the density functional force field applied, and better interaction force constants in the internal coordinates have been proposed. The valence force constants in the general quadratic valence force field were also given. The stretch-stretch interaction and stretch-bending interaction constants are not sensitive to the geometrical displacement in the valence force field.

Force constant

Force Field

Ferrocyanide

10.5012/bkcs.2002.23.2.253

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Citations (11)

Usefulness of $^{99m}Tc-HMPAO$ SPECT in the Localization of the Epileptic focus in Temporal Lobe Epilepsy: Comparison with EEG, MRI and CT

The Korean Journal of Nuclear Medicine (1991)

Jongho Kim Jong-Soon Kim Sang Eun Kim Chang-Woon Choi Dong‐Soo Lee

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Chemical Vapor Deposition of HfO₂ Thin Films Using the Novel Single Precursor Hafnium 3-Methyl-3-pentoxide, Hf(mp)₄

Chemistry of Materials (2005)

Taek Seung Yang Ki‐Seok An Eunjoo Lee Wontae Cho Hong Suk Jang

Hafnium oxide films have been deposited on silicon substrates by metal organic chemical vapor deposition using the novel single precursor, hafnium 3-methyl-3-pentoxide {Hf[OC(CH3)(C2H5)2]4, Hf(mp)4}, with no additional oxygen source, and the deposition mechanism was elucidated. Hf(mp)4 is a liquid at room temperature and has a moderate vapor pressure comparable to that of hafnium tert-butoxide, Hf(OtBu)4, and a lower residual weight (<10%) in thermogravimetric analysis. The deposition rate was found to be ∼27 Å/min at 400 °C, and the activation energy was 68.1 kJ/mol, which is higher than those of other hafnium alkoxide and hafnium amide precursors. By gas chromatography/mass spectroscopy and nuclear magnetic resonance analyses of the thermally decomposed vapor phase products collected during the deposition of HfO2 films, it was clearly found that they are grown via β-hydrogen elimination processes of the Hf(mp)4 single precursor. Negligible carbon incorporation of the HfO2 films, examined by X-ray photoelectron spectroscopy and depth-profiling Auger electron spectroscopy, indicates that, except for the β-hydrogen elimination processes, no additional decomposition and/or recombination processes contributed to the HfO2 film growth. The morphology, crystallinity, and electrical properties of the HfO2 films were characterized by scanning electron microscopy, atomic force microscopy, X-ray diffraction, and capacitance−voltage and current−voltage measurements.

Hafnium

10.1021/cm050662t

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Citations (22)

A Study on the Suppression of Instability Whirl of a Foil Bearing for High-Speed Turbomachinery beyond the Bending Critical Speed

Journal of Fluid Machinery (2002)

Yongbok Lee Tae‐Ho Kim Chang‐Ho Kim Nam-Soo Lee Dong-Hoon Choi

A new foil bearing, ViscoElastic Foil Bearing(VEFB) is suggested with the need for a high damping foil bearing. Sufficient damping capacity is a key technical hurdle to super-bending-critical operation as well as widespread use of foil bearings into turbomachinery. The super-bending-critical operation of the conventional bump foil bearing and the VEFB is examined, as well as the structural dynamic characteristics. The structural dynamic test results show that the equivalent viscous damping of the VEFB is much larger than that of the bump bearing, and that the structural dynamic stiffness of the VEFB is comparable or larger than that of the bump bearing. The results of super-bending-critical operation of the VEFB indicate that the enhanced structural damping of the viscoelastic foil dramatically reduces the vibration near the bending critical speed With the help of increased damping resulting from the viscoelasticity, the suppression of the asynchronous orbit is possible beyond the bending critical speed.

Turbomachinery

Foil bearing

Critical speed

Aeroelasticity

10.5293/kfma.2002.5.3.007

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Fourier Transform Raman Spectroscopic Investigation of Silver ion - Flavin Mononucleotide Complexation

Bulletin of the Korean Chemical Society (1991)

Nam-Soo Lee

Flavin mononucleotide

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Citations (2)

Numerical prediction of slip flow effect on gas-lubricated journal bearings for MEMS/MST-based micro-rotating machinery

Tribology International (2004)

Yong-Bok Lee Hyun-Duck Kwak Chang‐Ho Kim Nam-Soo Lee

Slip ratio

Fluid bearing

10.1016/j.triboint.2004.01.003

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Citations (65)

Room temperature ferromagnetism of Fe doped NiO films prepared by MOCVD

Proceedings of the Korean Vacuum Society Conference (2008)

Kyung-Chul Min Won Mook Chae Sun Sook Lee Young Kuk Lee Taek‐Mo Chung

Non-blocking I/O

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Fluidized Bed Incineration of Digested Sewage Sludge -Part 1. Combustion Characteristics of the Single-Stage Fluidized Bed Incinerator

Korean Journal of Chemical Engineering (1992)

Jea-Keun Lee Ki‐Ho Lee Jeong Gook Jang Nam-Soo Lee Jong-Sung Lim

Sewage sludge

Fluidized bed combustion

Freeboard

Heat of combustion

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Citations (3)

Synthesis and Separating Properties of Tris(Merrifield Peptide Resin)

Zeitschrift für Naturforschung B (2002)

Dong‐Won Kim Chang Suk Kim Nam-Soo Lee Haiil Ryu Jong Seung Kim

A triazacrown ion exchanger, 1,13,16-trioxa-4,7,10-triazacyclooctadecane (TOTA)-4,7,10- tris(Merrifield peptide resin) was synthesized. This resin has a capacity of 0.1 meq/g dry resin. The resin was used for the elution chromatographic separation of lithium isotopes. Upon column chromatography [0.2 cm I. D. x 35 cm height] using 3.0 M NH 4 Cl solution as an eluent, the single stage separation factor of 1.027 was obtained. The heavier isotope, 7 Li + , was enriched in the resin phase, while the lighter isotope, 6 Li + , was enriched in the solution phase.

Ion-exchange resin

Ion chromatography

10.1515/znb-2002-0113

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Citations (5)