• 대한기계학회논문집B
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• 제20권2호
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• pp.720-729
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• 1996

An analysis of convective boiling heat transfer for refrigerant mixtures is performed for an annular flow to investigate the degradation of the heat transfer rate. Annular flow is selected in this study because a great portion of the evaporator in the refrigeration and air conditioning system is known to be in the annular flow regime. Mass transfer effect due to composition difference between liquid and vapor is included in this analysis, which is considered to be one of driving forces for the mass transfer at the interface. Due to the concentration gradient at the interface the mass transfer is interfered, so is the evaporative heat transfer at the interface. The mass transfer resistance makes the interface temperature slightly higher and, as a result, the heat transfer coefficients decrease compared with those without mass transfer effects. The degradatioin of the heat transfer rate reaches its maximum at a certain composition. The composition difference between vapor core and vapor at the interface has a direct effect on the temperature difference between the vapor core and the interface and the degradation of the heat transfer rate. Correction factor $C_{F}$ for the mixture effects is added to the correlation for pure substances and the flow boiling heat transfer coefficients can be calculated using the modified equation.n.

• 한국약용작물학회지
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• 제19권1호
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• pp.24-30
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• 2011

This text was analyzed and investigated the vegetation and floristic composition by cluster analysis and classification of phytosociological method, to evaluate the species composition, habitat environment and community structure of Liriope platyphylla and Liriope spicata group in Korea. The southeast slope gradient of the habitat of L. platyphylla and L. spicata was 6.7 to 8.4%, and the habitat altitude of L. platyphylla (41.0 m), L. spicata (114.9 m) was different. Habitat distribution of L. spicata was broader than L. platyphylla. Appearing plants of L. platyphylla and L. spicata group was 58 taxa, 99 taxa, respectively, and Coverage of tree layer was 87.5%, 92.5% respectively. In genus Liriope group, the highest appearing frequency of plant grow in the moist valley as Quercus serrata. Thus, plants of genus Liriope growth was better in moist shade. The vegetation of L. platyphylla group was classified into Quercus serrata community, Castanopsis sieboldii community, Pinus densiflora community and Pinus thunbergii community, and the Liriope spicata group was classified into Quercus serrata community, Quercus alien community, Quercus acutissima community, Prunus verecunda community, Robinia pseudoacacia community, Pinus densiflora community and Pinus thunbergii community. In genus Liriope group, Quercus serrata and Pinus densiflora communities was the closest the similarities.

• Journal of Advanced Marine Engineering and Technology
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• 제10권4호
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• pp.57-66
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• 1986

The microstructure and mechanical properties of unidirectionally solidified Al-Fe-Ni and Al-Fe-B alloys have been studied in varying the some conditions. To investigate the change of microstructure and mechanical properties was carried out by the varying the composition and solidification rate from 1.2 to 80 mm/min at temperature gradient 60 .deg. C/cm. The results obtained are as follow; 1. In proportion to the increase of the solidification rate, the type of crystallized phase of these composite alloys was changed by added element. a) The crystallized phase of composite alloy in added nikel was changed from the rod-type fiber to platetype fiber. b) The crystallized phase of composite alloy in added boron was changed from the plate-type fiber to rod-type fiber. 2. The strength was rapidly increased with the changing process of crystallized fiber from the plate-type fiber to the rod-type.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.292-296
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• 2002

This study has been accomplished as a experimental study for field application of 3D Perspective Image Map creation using Digital Topographical Map and based on the Ortho-Projection Image which is generated from Satellite Overlay Images and the precise Relative Coordinates of longitude, latitude and altitude which is corrected by GCP(Ground Control Point). AS to Contour Lines Map which is created by Coordinate conversion of 1:5,000 Topographical Map, we firstly made Satellite Image Map to substitute for Digital Topographical Map through overlapping the original images on top of each Ortho-Projection Image created and checking the accuracy. In addition to 3D Image Map creation for 3D Terrain analysis of a target district, Slope Gradient Analysis, Aspect Analysis and Terrain Elevation Model generation, multidirectional 3D Image generation by DEM can be carried out through this study. This study is to develop a mapping technology with which we can generate 3D Satellite Images of a target district through the composition of Digital Maps and Facility Blueprint and arbitrarily create 3D Perspective Images of the target district from any view point.

• Applied Biological Chemistry
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• 제16권3호
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• pp.112-117
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• 1973

The very low density apolipoproteins were separated by a newly developed method of isoelectric focusing in a narrow pH gradient. Four polypeptides were isolated that differed from the major proteins of the high density or low density lipoproteins. Three of these proteins had indistinguishable amino acid compositions, but different isoelectric points, COOH-terminal alanine, no isoleucine, cysteine or cystine. Two of these polypeptides had $NH_2-terminal$ serine. The polymorphism of apolipoprotein-Ala, so designated from the COOH-terminal residue, was related to sialic acid content; one form contained 2 moles of sialic acid per mole of protein, the second, 1 mole of protein, and the third, no sialic acid. The fourth polypeptide had an amino acid composition different from the first three polypeptides and from other polypetides obtained from very low density lipoprotein. This polypeptide had $NH_2-terminal$ threonine, COOH-terminal resistant to carboxypeptidase A, no histidine, cysteine, cystine or sialic acid. These four polypeptides constituted approx. 40% of the total protein in very low density lipoprotein.

• 한국분말재료학회지
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• 제3권4호
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• pp.266-270
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• 1996

The microstructure evolution during sintering of a compact being composed of three layers of (WC-15%Co)/Fe powder mixture with different Fe contents has been observed. The Fe contents in the respective (WC-15%Co)/Fe layers were varied by 20%. 50%, and 90% in sequence by volume from a top layer to a bot- tom layer. The sintering temperatures and times were varied from 110$0^{\circ}C$ to 125$0^{\circ}C$ and from 1 h to 4 h, The compact layer was not densified below 120$0^{\circ}C$ in 4 h. Appropriate sintering temperature and time conditions for making a multi-layered hard metal compact were determined as 125$0^{\circ}C$ and 3 h, respectively.

• 한국표면공학회지
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• 제34권3호
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• pp.240-246
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• 2001

The possibility of using a glass block with the composition of sodium borosilicate as starting materials for GRIN glass was examined from the view points of the phase separation of the matrix glass, the effects of leaching and the heating conditions for a porous structure, and the change in the refractive index. Glass specimens with similar compositions were prepared in the form of porous glass using a phase-separation technique. An examination of the heating and leaching conditions and the microstructure dependence of these conditions was made.; Specimens with porous structure were obtained when the heat treatment and leaching conditions were fixed at $540^{\circ}C$ for 30hrs and in a 0.3N$ H_2$$SO_4$ solution at $100^{\circ}C$, respectively. The resultant specimens had some important features on the GRIN glass.; the depth of the gradient and the change in refractive index (Δn) were 4mm and 0.015~0.02, respectively.

• 한국수소및신에너지학회논문집
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• 제26권3호
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• pp.260-270
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• 2015

One-dimensional packed bed reactor model accounting for interfacial and intra-particle gradients was developed and based on it numerical analyses were performed to investigate the dynamic behavior of a commercial scale methanation reactor. Methanation reaction was almost complete near the reactor inlet and gases with equilibrated composition were discharged from the reactor. Both the intra-particle temperature gradient and differential surface temperature rise were found to be severe near the reactor inlet. To reduce the possible degradation or fracture of catalyst particles and prevent local overheating on the catalyst, addition of inert material can be an effective way.

• 한국결정성장학회지
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• 제5권4호
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• pp.386-393
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• 1995

SHS법에 의한 경사기능재료를 제조하는 방법을 조사하여 그 방법에 따라 $TiB_2/Cu$ 경사기능재료를 제조하고자 한다. 이때 원료분말을 구리에 침적하면서 조성의 구배를 주고, 가압 성형한 후 합성을 하기 위한 반응조에 넣었다. 이 시료를 점화시켜 정수압 하에서 합성과 동시에 가압하였다. 이렇게 제조된 $TiB_2/Cu$ 경사기능재료의 결정상, 미세주고 등을 관찰하여 조성의 경사를 확인할 수 있었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1374-1377
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• 2006

The voltage distribution of an external electrode fluorescent lamp(EEFL) having a gas pressure of 50 torr and a gas composition of Ne:Ar with a ratio of 90:10 has been estimated by varying the distance between the two external electrodes and monitoring the change of the lamp voltage. The estimated voltage gradient, which represents the electric field in the positive column of the EEFL, was very sensitive to the electrode area of EEFL and was in the range of $13\;{\sim}\;27\;V/cm$ at the electrode length of $15\;{\sim}\;31\;mm$. Changing the lamp current in the range $3\;{\sim}\;5\;mA$ did not make noticeable difference in the electric field of the positive column. Theses results may serve as basic data for the optimization of electric and optic characteristics of EEFL.