• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1343-1344
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• 2010

Pyridine dicarbonitriles have been synthesized good yields via a one-pot multi.component reaction of aldehyde, malononitrile, and thiol in the presence of sodium silicate as a catalyst in ethanol.

• 한국가스학회지
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• 제7권3호
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• pp.32-43
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• 2003

이 연구는 단성분계(메탄)과 다성분계(천연가스) 하이드레이트의 상평형 조건을 관찰하고, 반응시간에 따른 하이드레이트 생성 거동을 관찰하여 비교 분석하였다. 단성분과 다성분계 하이드레이트의 차이점은 크게 유도지체시간과 안정 영역이다. 반응시 다성분계 하이드레이트는 가스의 성분들이 서로 다른 농도변화를 나타내었으며, 제조된 하이드레이트를 해리시켰을 때도 서로 다른 해리 속도에 의해 각 가스 성분들의 농도가 변화되었다. 압력이 6 MPa이고, 온도가 276.65 K이며, 교반속도가 600 rpm일때 다성분계 하이드레이트 제조시 메탄이외의 여러 가스 성분들에 의해 하이드레이트 핵 생성이 빠르게 진행되어 유도지체시간은 짧다. 그리고 단성분계 하이드레이트는 단일 성분으로 이루어져 있으므로 안정 영역이0.055 mole of $CH_4$/mole of water에서 보다 뚜렷하게 관찰되고, 다성분계 하이드레이트는 안정 영역이 0.04 mole of $CH_4/$mole of water에서 관찰된다.

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.656-658
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• 2011

A green and efficient method for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones and -thiones through one-pot three-component reaction of ethyl acetoacetate, an aryl aldehyde, and urea or thiourea in acetonitrile using silica gel-supported polyphosphoric acid (PPA-$SiO_2$) as catalyst is described. Compared to the classical Biginelli reaction conditions, the present methodology offers several advantages such as high yields, relatively short reaction times, mild reaction condition and a recyclable catalyst with a very easy work up.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.377-378
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• 2012

• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2532-2534
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• 2009

A facile and efficient synthetic route has been developed for the polyhydroquinoline via four component reactions of aldehydes, dimedone, ethyl acetoacetate and ammonium acetate in the presence of catalytic amount of scolecite in ethanol at 70 ${^{\circ}C}$ through Hantzsch reaction. This method gives remarkable advantages such as simple work-up procedure, environmentally friendly, inexpensive, non-toxic and recyclable catalyst, shorter reaction time along with excellent yields.

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1679-1684
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• 2011

Interfacial reactions kinetics often differ from kinetics of bulk reactions. Here, we describe how the density change of an immobilized reactant influences the kinetics of interfacial reactions. Self-assembled monolayers (SAMs) of alkanethiolates on gold were used as a model interface and the Diels-Alder reaction between immobilized quinones and soluble cyclopentadiene was used as a model reaction. The kinetic behavior was studied using varying concentrations of quinones. An unusual threshold density of quinones (${\Gamma}_c$ = 5.2-7.2%), at which the pseudo-first order rate constant started to vary as the reaction progressed, was observed. This unexpected kinetic behavior was attributed to the phase-separation phenomena of multi-component SAMs. Additional experiments using more phase-separated two-component SAMs supported this explanation by revealing a significant decrease in ${\Gamma}_c$ values. When the background hydroxyl group was replaced with carboxylic or phosphoric acid groups, ${\Gamma}_c$ was observed at below 1%. Also, more phase-separated thermodynamically controlled SAMs produced a lower critical density (3% < ${\Gamma}_c$ < 4.9%) than that of the less phaseseparated kinetically controlled SAMs (6.5% < ${\Gamma}_c$ < 8.9%).

• Bulletin of the Korean Chemical Society
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• 제31권3호
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• pp.553-554
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• 2010

• 보건의료산업학회지
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• 제9권3호
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• pp.255-266
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• 2015

Objective : The aim of this study was to examine the effects of the Home-based Multi-component Activity Program (Home-MAP) for the maintenance activities of daily living (ADL) for patients with mild Alzheimer's disease (AD) and on caregiver burden for caregivers. Methods : Nine mild AD patients and family caregivers. The Home-MAP was performed 1d/wk, for a total of 10 times over 10 weeks. Results : After the 10 sessions, participants' motor and process skills scores on the AMPS were found to have significantly improved (p=.028 and p=.028, respectively). The BPSD frequency score on the R-MBPC was found to be significantly reduced (p=.017). The BPSD symptoms related to caregiver reaction score on the R-MBPC and distress score on the NPI-Q were significantly reduced (p=.039 and p=.018, respectively). Conclusions : The Home-MAP appears to have contributed to the improvement of patients' capabilities in performing in ADL, to a reduction of BPSD, and to a reduction of burden related to BPSD.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.63-66
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• 2007

Reformers which produce hydrogen from natural gas are essential for the operation of residential PEM fuel cells. For this purpose, steam-methane reforming reactions with Ni catalysts is primarily utilized. Commercial Ni catalysts are generally made to have porous pellet shapes in which Ni catalyst particles are uniformly dispersed over Alumina support structures. This study numerically investigates the reduction of catalyst effectiveness due to the mass transport resistances posed by porous structures of spherical catalyst pellets. The multi-component diffusion through porous media and the accurate kinetics of reforming reaction is fully considered in the numerical model. The preliminary results on the variation of the effectiveness factor according to different operation conditions are presented, which is planned to be used to develop correlations in future studies.

• 한국주조공학회지
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• 제26권1호
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• pp.27-33
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• 2006

Phase evolutions involving nucleation stages together with diffusional growth have been examined in order to provide a guideline for determining rate limiting stages during phase evolutions. In multiphase materials systems in coatings, composites or multilayered structures, diffusion treatments often result in the development of metastable/intermediate phases at the reaction interfaces. The development of metastable phases during solid state interdiffusion demonstrates that the nucleation reaction can be one controlling factor. Also, the concentration gradient and the relative magnitudes of the component diffusivities provide a basis for a phase selection and the application of a kinetic bias strategy in the phase selection. For multicomponent alloy systems, the identification of the operative diffusion pathway is central to control phase formation. Experimental access to the nucleation and growth stage is discussed in thin film multi layers and bulk samples.