• Bulletin of the Korean Chemical Society
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• 제12권2호
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• pp.219-224
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• 1991

New binuclear Ni(Ⅱ) and Cu(Ⅱ) complexes with various alkyl derivatives of 1,2-bis(1,3,6,8,10,13-hexaaza-1-cyclotetradecyl) ethane, in which two fully saturated 14-membered hexaaza macrocyclic subunits are linked together by an ethylene chain, have been synthesized by the one step template condensations of formaldehyde with ethylenediamine and appropriate primary alkyl amines in the presence of the metal ions. Each macrocyclic subunit of the double-ring macrocyclic complexes contains one alkyl pendant arm and has a square planar geometry with a 5-6-5-6 chelate ring sequence. The visible spectra and oxidation properties indicate that the metal-metal interaction of the binuclear complexes are not significant. Synthesis, characterization, and the properties of the complexes are presented.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1400-1402
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• 2010

• Bulletin of the Korean Chemical Society
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• 제30권6호
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• pp.1368-1372
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• 2009

• 한국재료학회:학술대회논문집
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• 한국재료학회 2006년도 춘계학술발표대회 및 제10회 신소재 심포지엄 논문개요집
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• pp.31.2-31.2
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• 2006

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2006년도 추계학술발표회 초록집
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• pp.83-83
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• 2006

• KEPCO Journal on Electric Power and Energy
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• 제4권1호
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• pp.25-31
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• 2018

A boiler system transforms water to pressured supercritical steam which drives the running of the turbine to rotate in the generator to produce electricity in power plants. Materials for building the tube system face challenges from high temperature creep damage, thermal fatigue/expansion, fireside and steam corrosion, etc. A database on the creep resistance strength and steam oxidation of the materials is important to the long-term reliable operation of the boiler system. Generally, the ferritic steels, i.e., grade 1, grade 2, grade 9, and X20, are extensively used as the superheater (SH) and reheater (RH) in supercritical (SC) and ultra supercritcal (USC) power plants. Currently, advanced austenitic steel, such as TP347H (FG), Super304H and HR3C, are beginning to replace the traditional ferritic steels as they allow an increase in steam temperature to meet the demands for increased plant efficiency. The purpose of this paper is to provide the state-of-the-art knowledge on boiler tube materials, including the strengthening, metallurgy, property/microstructural degradation, oxidation, and oxidation property improvement and then describe the modern microstructural characterization methods to assess and control the properties of these alloys. The paper covers the limited experience and experiment results with the alloys and presents important information on microstructural strengthening, degradation, and oxidation mechanisms.

• 한국분말재료학회지
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• 제18권2호
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• pp.141-148
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• 2011

Carbon material shows relatively high strength at high temperature in vacuum atmosphere and can be easily removed as CO or $CO_2$ gas in oxidation atmosphere. Using these characteristics, we have investigated the applicability of carbon mold for precision casting of high melting point metal such as nickel. Disc shape carbon mold with cylindrical pores was prepared and Ni-base super alloy (CM247LC) was used as casting material. The effects of electroless Nickel plating on wettability and cast parameters such as temperature and pressure on castability were investigated. Furthermore, the proper condition for removal of carbon mold by evaporation in oxidation atmosphere was also examined. The SEM observation of the interface between carbon mold and casting materials (CM247LC), which was infiltrated at temperature up to $1600^{\circ}C$, revealed that there was no particular product at the interface. Carbon mold was effectively eliminated by exposure in oxygen rich atmosphere at $705^{\circ}C$ for 3 hours and oxidation of casting materials was restrained during raising and lowering the temperature by using inert gas. It means that the carbon can be applicable to precision casting as mold material.

• 한국환경과학회지
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• 제16권12호
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• pp.1431-1437
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• 2007

Cobalt titanates($CoTiO_x$), such as $CoTiO_3$ and $Co_2TiO_4$, have been synthesized via a solid-state reaction and characterized using X-ray diffraction(XRD) and X-ray photoelectron spectroscopic(XPS) measurement techniques, prior to being used for continuous wet trichloroethylene(TCE) oxidation at $36^{\circ}C$, to support our earlier chemical structure model for Co species in 5 wt% $CoO_x/TiO_2$(fresh) and(spent) catalysts. Each XRD pattern for the synthesized $CoTiO_3$ and $Co_2TiO_4$ was very close to those obtained from the respective standard XRD data files. The two $CoTiO_x$ samples gave Co 2p XPS spectra consisting of very strong main peaks for Co $2p_{3/2}$ and $2p_{1/2}$ with corresponding satellite structures at higher binding energies. The Co $2p_{3/2}$ main structure appeared at 781.3 eV for the $CoTiO_3$, and it was indicated at 781.1 eV with the $Co_2TiO_4$. Not only could these binding energy values be very similar to that exhibited for the 5 wt% $CoO_x/TiO_2$(fresh), but the spin-orbit splitting(${\Delta}E$) had also no noticeable difference between the cobalt titanates and a sample of the fresh catalyst. Neither of all the $CoTiO_x$ samples were active for the wet TCE oxidation, as expected, but a sample of pure $Co_3O_4$ had a good activity for this reaction. The earlier proposed model for the surface $CoO_x$ species existing with the fresh and spent catalysts is very consistent with the XPS characterization and activity measurements for the cobalt titanates.

• 한국식품과학회지
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• 제24권6호
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• pp.535-540
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• 1992

음양곽(Epimedium koreanum N.)의 methanol 추출물을 각종 식용유지에 첨가하여 $75^{\circ}C$에서 저장하면서 과산화물가의 변화를 측정하므로서 항산화성을 검토하였던 바 유지의 종류에 따라 효력에 차이를 나타내었고 lard와 corn oil에 대한 항산화 효과가 인정되었으며, 특히 lard에 대하여는 항산화 효과가 켰으며 첨가농도에 따라 효과가 증대되었다. 음양곽 추출물을 $180^{\circ}C$에서 120분간 가열하였을 때에도 66% 이상의 항산화성이 잔존하였으나 대두유에 첨가하여 광산화에 미치는 영향을 검토한 결과 자외선 조사에 의하여 급격히 산화가 촉진되었다. 음양곽 methanol 추출물 중의 유효 항산화 성분은 tocopherol류와 flavonoid류로 추정되었으며 ${\alpha}$, ${\beta}$, ${\gamma}$ and ${\delta}-tocopherol$의 함량은 각각 21.61, 1.48, 5.50 및 3.75 mg%이었다.

• 공업화학
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• 제20권1호
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• pp.28-33
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• 2009

카본나노튜브에 담지된 몰리브데늄 카바이드 촉매를 다양한 제조 조건을 통해 제조하여 촉매특성을 분석하였고, 메탄올의 전기화학적 산화반응을 통해 촉매의 활성을 비교하였다. 촉매로써 전이금속의 낮은 활성을 극복하기 위한 방안으로 카본나노튜브를 지지체로 사용하였으며 전구체의 양 및 종류, 지지체의 산처리 방법, 탄화공정 온도조건 등을 변화하여 촉매를 제조하였다. 제조된 촉매는 ICP-AES, XRD, TEM을 통하여 촉매의 특성을 분석하였고, 메탄올의 전기화학적 산화반응을 통해 촉매의 활성을 비교하였다. 몰리브데늄 카바이드 촉매($Mo_2C/CNT$)의 다양한 제조방법으로 입자크기와 담지량을 변화시킬 수 있었으며, 입자의 크기와 담지량의 변화에 따른 전기화학적 산화반응의 특성을 설명할 수 있었다.