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CH Lee

Publications and source records attributed to CH Lee.

At least 19 recordsLinked to original sources
PubMed2000

Convenient route to super-expanded calixpyrroles: synthesis of Calix

meso-Alkylporphyrinogen-like cyclic oligomers containing furans and pyrroles have been synthesized by "3 + 2" and "4 + 2" approaches. Condensation of 5,5,10,10,15,15-hexaethyl-21, 22-dioxatetrapyrromethane with 2,5-bis[(alpha-hydroxy-alpha, alpha-dimethyl)furan] resulted in the formation of cyclic hexamer and cyclic dodcamer. Effects of catalysts, temperature, inorganic additives, solvent, and reaction concentration were examined.

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PubMed2000

Interconversion between µ-eta(2),eta(2)-C(60) and µ(3)-eta(2),eta(2),eta(2)-C(60) on a Carbido Pentaosmium Cluster Framework We are grateful to the Korea Science Engineering Foundation (KOSEF) for financial support (project no. 1999-1-122-001-5) of this research and a postdoctoral fellowship to K.L. The X-ray diffraction studies were carried out at the X-ray Crystallographic Laboratory of Yonsei University, which was supported in part by KOSEF.

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PubMed2000

Simulation of spatial fuel assay using HANARO neutron beam

A sensitivity simulation of neutron tomography was performed for the analysis of the spatial distribution of nuclear materials in the HANARO fuel rod. The internal distribution of the nuclear materials in the fuel rod is very important for the increase of the safety and economics of fuel burnup in the reactor. The neutron radiography facility installed at HANARO will be used for the spatial fuel analysis with a real-time image processing system. Monte Carlo simulation was performed to study the feasibility and sensitivity of the HANARO neutron beam for the spatial fuel assay and to find the optimum conditions for neutron detection. From the sensitivity simulation, the location of the nuclear materials in the rod was evident as expected.

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PubMed1999

The crystal structure of the B-site ordered complex perovskite Sr(Yb0.5Nb0.5)O3.

The room-temperature crystal structure of the B-site ordered complex perovskite strontium ytterbium niobate, Sr(Yb(0.5)Nb(0.5))O(3) [monoclinic, Z = 2, P2(1)/n (set 2), a = 5.79095 (8), b = 5.82210 (7), c = 8.20358 (12) Å, beta = 90.126 (1) degrees, with final R(wp) = 0.0595, R(Bragg) = 0.0203 for the neutron profile and R(wp) = 0.0832, R(Bragg) = 0.0193 for the X-ray profile, respectively], was determined by X-ray powder diffraction, high-resolution neutron powder diffraction and transmission electron microscopy. This compound shows a slight triclinic distortion from the prototype doubled cubic perovskite cell as a result of an a(-)a(-)c(+)-type oxygen octahedral tilting distortion. It is also shown that the site ordering of the different species of B-site cations, Yb(3+) and Nb(5+), inherently leads to a difference between the volumes of the YbO(6) and NbO(6) octahedra. This volume difference is shown to inevitably inhibit the rigid rotation of octahedra.

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PubMed1999

Antithyroid drug-induced agranulocytosis.

Thyrotoxicosis is a common endocrine disorder. Antithyroid drug therapy is the standard treatment for this disease, especially in young women of reproductive age. A serious side effect of antithyroid drug use, however, is agranulocytosis. We report on two patients with antithyroid drug-induced agranulocytosis. Both patients presented with fever and severe neutropenia. The administration of granulocyte colony-stimulating factor resulted in a dramatic improvement in the white blood cell count and symptoms. Antithyroid drug-induced agranulocytosis is a potentially lethal condition but is completely reversible when recognised early and when prompt treatment is offered.

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