• Journal of Electrochemical Science and Technology
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• 제1권1호
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• pp.19-24
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• 2010

Alloying degree is an important structural factor of PtRu catalysts for direct methanol fuel cells (DMFC). In this work, carbon supported PtRu catalysts were synthesized by reduction method using anhydrous ethanol as a solvent and $NaBH_4$ as a reducing agent. Using anhydrous ethanol as a solvent resulted in high alloying degree and good dispersion. The morphological structure and crystallanity of synthesized catalysts were characterized by X-ray diffraction (XRD), high resolution transmission electron microscope (HR-TEM). CO stripping and methanol oxidation reaction were measured. Due to high alloying degree catalyst prepared in anhydrous ethanol, exhibited low onset potential for methanol oxidation and negative peak shift of CO oxidation than commercial sample. Consequently, samples, applying ethanol as a solvent, exhibited not only enhanced CO oxidation, but also increased methanol oxidation reaction (MOR) activity compared with commercial PtRu/C (40 wt%, E-tek) and 40 wt% PtRu/C prepared in water solution.

• 대한전기학회논문지
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• 제41권9호
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• pp.1085-1094
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• 1992

A variable-spacing cesium thermionic energy conversion test station is designed and fabricated for the study of power generation. The diode is in the form of a guard-ringed plane-parallel geometry in which a polycrystalline rhenium emitter of 2 cmS02T area faces a radiation-cooled polycrystalline rhenium collector of 1.9 cmS02T area. The emission of plasma from heated refractory electrode metal is the driving reaction in the direct conversion of heat to electricity by thermionic energy conversion. The plasma is produced from electrons and positive ions formed simultaneously by thermionic emission and surface ionization of cesium atoms incident on the hot emitter from the cesium vapor in the diode. And high plasma density causes plasma multiplication within the gap due to volume ionization that results in high power output. The variation of the saturation current of a Knudsen converter is investigated at an emitter-collector gap of 0.1 mm and an emitter temperatures. A maximum power output of 13.47 watta/cmS02T is observed at a collector temperature of 963 K and a cesium reservoir temperature of 603 K.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.112-116
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• 2011

In this paper, a preconverter of MCFC for an emergence electric power supplier is numerically simulated to increase the hydrogen production from natural gas (methane). Commercial code is used to simulated the porous catalyst with user subroutine to model three dominant chemical reactions which are Stream Reforming(SR), Water-Gas Shift(WGS), and Direct Stram Reforming(DSR). To get 10% fuel conversion rate in preconverter. the required external heat flux is supplied from outer wall of preconverter. The calculated results show that very nonuniform temperature distribution and chemical reaction happen near the wall of preconverter. These phenomena can be explained by the low heat conductivity of porous catalyst and the endothermic reforming reaction.

• 자연과학논문집
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• 제8권2호
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• pp.129-136
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• 1996

염화물을 이산화질소기체로 반응시킬때와 같이 고체 염화칼륨으로부터 고체 질산칼륨으로의 직접적인 전환이 질산칼륨의 생성을 암시하고 있음을 확인하였다. 또 열역학적 추정에 있어서 자유에너지 변화는 상온에서 유리하며 발열반응을 보여준다. 그리고 높은 수율과 함께 적은양의 물존재로 인하여 상온에서 반응이 일어나며 반응생성물에서 염화니트로실이 동시에 생성되고 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.617-618
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• 2006

A CMOS quadrature Up-converter for a direct-conversion receiver of 5.15-5.825GHz wireless LAN is described. The Up-converter consists of two sub-harmonic mixers, for I and Q channels, and an LO generation network. In order to decrease the number of inductor, I and Q path are merged. The simulation results including all the parasitics show -17.3dB conversion gain at center and -8 dBv oIP3 while consuming 22.968mW under 1.8V supply. The quadrature Up-converter is under fabrication with the other transmitter blocks in a $0.18{\mu}m$ CMOS technology.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제14권4호
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• pp.323-332
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• 2010

It is the development of a mathematics teachers' teaching knowledge that manifests a mathematics teacher's professional knowledge growth. It is becoming a direct and effective approach of conversion of mathematical knowledge into the knowledge of mathematics teaching. Through the investigation, the study revealed that the knowledge conversion process of mathematics teachers in middle school is restricted by three aspects including eight factors. From this point, the authors have structured the path and model on influencing factors of middle school Mathematics Teaching Knowledge Conversion (MPCK), and discuss the mechanism of the transformation process.

• 농촌지도와개발
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• 제13권2호
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• pp.357-373
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• 2006

The study aims to explore the individual and group agreement of the direct payment of less-favored areas in Japan. This study was conducted by literature review, specialist interview and field visiting. The results of this study were as follows. First, direct payment policy in Japan was consisted of three components which were to maintaining multiple functions, to reorient agriculture sector, and to revitalizing the community activities. Second, the purposes of direct payments with conversion program is to reorient agriculture and revitalize the community activities which were changed from sustaining existing agriculture. Third, the conditions of group agreement is to make a agreement that a group of farmers should make a five-year agreement stipulating activities necessary to prevent the abandonment of farmland and to be more than one hector, and good agricultural practice or other activities favorable or friendly to environment should be implemented. As individual and group agreement, the land area of direct payment was 662,000 ha in less favored areas. In conclusion after direct payment in less favored areas, the abandonment of farmland was mitigated, and the agricultural production activities and community activities had become more vigorous through the discussion for planning their own land in the village.

• 대한한방내과학회지
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• 제25권3호
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• pp.590-595
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• 2004

Conversion Disorder is a disorder whose predominant feature is a loss or alteration in physical functioning that suggests a physical disorder but that is actually a direct expression of a psychological conflict or need. The Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) guidelines for Conversion Disorder include these definitions: A psychosocial stressor produces a psychological conflict that is believed to help initiate or exacerbate the illness The symptoms are not under conscious control, etc. While functional disabilities are common with conversion disorders, physical and laboratory abnormalities are absent or minor in comparison with the patient's subjective complaints. Symptoms of Conversion Disorder are similar to those of stroke. But the mechanism of Conversion Disorder is similar as that of Stagnation Syndrome of Ki (氣鬱證) in Oriental medicine. Gaegyeolseogyeong-tang has been used to treat women who suffer from Conversion Disorder induced by the Stagnation Syndrome of Ki (氣鬱證). After application of the Gaegyeolseogyeong-tang for 7 days, symptoms and signs improved dramatically.

• 한국수소및신에너지학회논문집
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• 제23권5호
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• pp.503-512
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• 2012

There is a new power generation system such as direct coal fuel cell (DCFC) with a solid oxide electrolyte operated at relatively high temperature. In the system, it is of great importance to feed coal continuously into anodic electrode surface for its better contact, otherwise it would reduce electrochemical conversion of coal. For that purpose, it is required to improve the electrochemical conversion efficiency by using either rigorous mixing condition such as fluidized bed condition or just by recirculating coal particle itself successively into the reaction zone of the system. In this preliminary study, we followed the second approach to investigate how significantly particle recycle would affect the coal conversion efficiency. As a first phase, coal conversion was analyzed and evaluated from the thermochemical reaction of carbon with air under particle recirculating condition. The coal conversion efficiency was obtained from raw data measured by two different techniques. Effects of temperature and fuel properties on the coal conversion are specifically examined from the thermochemical reaction.

• 상하수도학회지
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• 제14권4호
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• pp.328-336
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• 2000

In order to compare the effect of water quality on two service systems, tank and direct connection service, we selected randomly 30 rooftop tanks installed in the buildings with five or fewer floors, and collected water samples from each tank as well as tap water by direct service. At the same time each tank was investigated on their cleanliness and sanitary control. 30 water samples from direct service met Korean Drinking water quality standard. But 5 tank water samples(17%) were not able to meet Coliform or Total Colony Counts standard and free chlorine of 12 tank water samples(40%) were less than 0.2mg/L. Also Fe, Turbidity, TOC, Total Algae in tank water were higher than tap water on direct service. We concluded that thorough health control of water tank is necessary and conversion into direct connection service results in improving tap water quality importantly.