• Journal of the Korean Applied Science and Technology
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• v.30 no.4
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• pp.726-739
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• 2013

Fischer-Tropsch synthesis (FTS) converts synthesis gas (CO and $H_2$) into longer chain hydrocarbons by a surface polymerization reaction. Cobalt- or iron-based catalysts normally show excellent activity for syngas conversion to petroleum products leading to super clean diesel fuels. The catalytic activities of the catalysts in FTS depend on the number of active sites on the surface. The number of active site was determined by the active metal particle size, loading amount, reduction degree and support-active metal interaction. The investigation adopts new methodology in preparing FT catalyst, which contains the controlled synthesis of active metal. The main focus of this paper is to give an overview of the types of catalysts, also including their preparation and reduction; the types of FT reactors; and also including the reaction conditions.

• BMB Reports
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• v.31 no.2
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• pp.201-208
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• 1998

Amino acid analogs, like other inducers of stress response, induce the synthesis of stress proteins in mammalian cells. In this study, Drosophila Kc cells, in which translation is tightly controlled during stress response, was treated with proline analogs, L-azetidine-2-carboxylic acid (AzC) and 3,4-dehydro-L-proline (dh-P). Kc cells exposed to AzC or dh-P induced the synthesis of several proteins which had the same molecular weights as known heat shock proteins. However, in Kc cells, normal protein synthesis still continued in the presence of amino acids analogs unlike in heat-shocked cells. For the induction of stress response, the incorporation of dh-P into the protein was not essential, but the incorporation of AzC was. The stress protein synthesis was regulated mainly at the transcriptional level by AzC, whereas it was regulated by dh-P at the transcription level and possibly posttranscription level. During recovery, the stress protein synthesis stopped sooner in analog-treated cells than in heat-shocked cells even though the accumulated amount of Hsp70 was much less in proline analogstreated cells. It could be concluded that the proline analogs, AzC and dh-P, induced stress response through a different mechanism from heat shock.

• Polymer(Korea)
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• v.25 no.5
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• pp.609-616
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• 2001

The application of microwave technology to synthesis of polymer in solvent media has been shown by the synthesis of copper phthalocyanine (CUPc). The increase of synthetic yield-was demonstrated successfully in this study. A power variable microwave synthetic system has been developed with modifying cavity of domestic microwave oven and attaching microwave power controller. The properties of the specimen synthesized at various condition under the conventional thermal processing and microwave processing has been characterized by the means of chemical analysis, X-ray diffractometry (XRD), scanning electron microscopy (SEM), and particle size analysis (PSA).

• Proceedings of the KSAR Conference
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• 2002.06a
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• pp.50-50
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• 2002

During fertilization, morphological and molecular events in male and female chromatin are precisely controlled in time. However, little information is available on onset of pronuclear formation and first S-phase entry in the pig following intracytoplasmic sperm injection. To assess species specific paternal effect on the pronuclear formation and initiation of first S-phase in the pig, we examined time of onset of male and female pronuclear formation and onset of DNA synthesis in the oocytes following pig or mouse sperm injection. (omitted)

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2000.11a
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• pp.11-12
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• 2000

Non-stoichiometric ceramics of $Ni_{x}ZnO_{1-x}Fe_{2}O_{4}$ were prepared by self-propagating high temperature synthesis reaction with various processing conditions and their stoichometric numbers were determined by neutron diffraction. The neutron diffraction patterns were measured at room temperature using monochromatic neutrons with a wave length of 0.18339 nm from a Ge(331) mocochromator at a 90 degree take off angle. The Rietveld refinement of each pattern converged to good agreement (x2=1.88-2.24). The neutron diffraction analysis revealed the final stoichiometries of the ferrites were $Ni_{0.38}Zn_{0.62}Fe_{2}O_{4}$ and $Ni_{0.33}Zn_{0.67}Fe_{2}O_{4]$, respectively. This supports that final stoichiometric number of the self-propagating high temperature synthesis product can be controlled by the processing parameters during the combustion reaction.

• Journal of the Korean Ceramic Society
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• v.35 no.7
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• pp.749-756
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• 1998

TiC-Ni and TiC-Ni-Mo cermet powders were produced by Self-propagating High temperature Synthesis (SHS) process. The cooling rate of synthesized powders were controlled by using the V-shaped copper jig and the carbide size decreased with increasing the cooling rate I. e decreasing the width of copper jig Round shape carbide particles were produced after SHS reaction in TiC-Ni as well as TiC-Ni-Mo powders. Local segregation of Mo rich phases was observed in SHS powder of TiC-Ni-Mo and the uneven dis-triobution of Mo promoted the faster growth rate of carbide particles during sintering compared to the same composition specimen with commercial TiC powder. Howogeneous microstructure of TiC-Ni-Mo cermet was obtained when the elemental Mo powder was mixed with the SHS powder of TiC-Ni.

• Journal of the Korean Chemical Society
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• v.34 no.4
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• pp.370-376
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• 1990

Synthesis of aluminium nitride has been studied by using the starting materials such as-alumina which was prepared at the lowest temperature from AlO(OH), anhydrous aluminium chloride and metallic aluminium powders. For the synthesis of aluminium nitride, the reaction temperature was carefully controlled and the reaction conditions were determined and discussed with the results. Reaction of metallic aluminium powder and nitrogen gas was taken place at relatively low temperature. The reaction parameters were determined kinetically.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.122-129
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• 1999

A 5-axis CNC machine tool is more useful compared with a 3-axis machine tool, because the position and the orientation of a tool tip can be controlled simultaneously. Unlike the 3-axis machine tool, the 5-axis machine tool has the volumetric position error and volumetric orientation error due to the quasi-static error of each machine tool joint which is a major source of machined part error. So, the generalized error synthesis model of the 5-axis CNC machine tool was developed to predict and to compensate for the volumetric position error and the volumetric orientation error. It was proposed that a compensation algorithm to correct simultaneously the volumetric position error and the volumetric orientation error of the 5-axis CNC machine by error inverse kinematic.

• Macromolecular Research
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• v.16 no.2
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• pp.85-102
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• 2008

The development of reliable synthetic routes to polymer nanomaterials with well-defined size and morphology is a critical research topic in contemporary materials science. The ability to generate nanometer-sized polymer materials can offer unprecedented, interesting insights into the physical and chemical properties of the corresponding materials. In addition, control over shape and geometry of polymer nanoparticles affords versatile polymer nanostructures, encompassing nanospheres, core-shell nanoparticles, hollow nanoparticles, nanorods/fibers, nanotubes, and nanoporous materials. This review summarizes a diverse range of synthetic methods (broadly, hard template synthesis, soft template synthesis, and template-free synthesis) for fabricating polymer nanomaterials. The basic concepts and significant issues with respect to the synthetic strategies and tools are briefly introduced, and the examples of some of the outstanding research are highlighted. Our aim is to present a comprehensive review of research activities that concentrate on fabrication of various kinds of polymer nanoparticles.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.67-75
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• 1998

Geometric and thermal errors are key contributors to the errors of a computer numerically controlled turning center. A planar error synthesis model is obtained by synthesizing 11 geometric and thermal error components of a turning center with homogeneous coordinate transformation method. This paper shows the sensitivity analysis on the temperature change, the confidence evaluation on the uncertainty Of measurement systems, and the error contribution analysis from the planar error synthesis model. Planar error in the z direction was very sensitive to the temperature change. and planar errors in the x and z directions were not affected by the uncertainty of measurement systems. The error contribution analysis ,which is applicable to designing a new turning center, was helpful to find the large error components which affect planar errors of the turning center.