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李豊憲 홍익대학교 산업기술연구소 1995 産業技術 Vol.5 No.-
Through ZnO Substitution in spinel type ZnCr_2O_4 with CoO NiO CuO were synthesized by method of coprecipitation. Its crystal structure was confirmed with x-ray diffraction analysis asnd scanning electron micrograph and its thermochemical properties were inspected by TG-DTA analysis. The gas sensing characteristics and its mechanism were studied by measuring the electerical resistance in the various concentration of propane. These synthesized compounds were found to be spinel type cubic structure. The substiation fo CoO NiO and CuO shoued excellent gas sensitivity. The response in propane environment reached the maximum value at avout 2000ppm of each gas content. The gas sensitivity reached a maximim peak at the operating temperature of 400℃ and this was the temperature at which the exothermic peak appeared on DTA curve. Theresponse properties of these compounds to propane showed the characteristics of p-type semiconductor.
ZnCr_2O_4의 습도감지 특성에 미치는 MgO및 PbO의 치환효과
李豊憲 홍익대학교 산업기술연구소 1994 産業技術 Vol.4 No.-
Through ZnO substitution in spinel type ZnCro_2O_4 with MgO or PbO were synthesized by the method of coprecipitation. Its crystal structure was confirmed with x-ray diffraction analysis and scanning electron micrograph. The humidity sensing characterostics and its mechanism were studied by measuring the electical resistance in the various concentration of moisture. These syntesized compounds were found to be spine type cubic structure. The Humidity sensing ability was improved by substitution of MgP or PbO.
韓國人에서 血友病 B 遺傳子(血液凝固因子 Ⅸ)의 構造 및 制限酵素 Dde Ⅰ, MnI Ⅰ 切片길이 多形性에 關한 分子 遺傳學的 考察
이풍연,전봉균,이정민,권오병,권무식 성균관대학교 생명과학자원연구소 1996 生命資源科學硏究 Vol.2 No.2
Hemophilia B, a human chromosome X-linked recessive disease, is a bleeding disorder resulting from defect or abnormality in blood coagulation factor IX. DNA-based prenatal diagnosis or carrier detection for hemophilia B in Korean has been developed by analyzing restriction fragment length polymorphisms(RFLPs). Two polymorphisms( Dde I and Mnl I) were investigated as follow. Genomic DNAs were extracted from blood of 50 females at the age of twenty. The primers were chemically synthesized by the method of phosphoamidite. Mnl I primers were derived from exon 6, while Dde I primers, from the flanking sequences of intron 1 of the factor IX gene. Genomic DNAs were amplified with Mnl I primers to generate 405 nts long fragments in all cases. They were digested with Mnl I to analyze the polymorphic site on agarose gel. No MnlI polymorphic site was found in all cases. Also, the genomic DNAs were amplified with Dde I primers to generate ca. 320 nts long fragments in all cases. These results are not correlated with those obtained from the Caucasian. It suggests that Korean could exhibit different patterns of Dde I and Mnl I polymorphisms in the gene for blood coagulation factor IX. Direct sequencing of the polymorpic sites will confirm the above sugestion.
李豊憲,李揆鎭 홍익대학교 산업기술연구소 2003 産業技術 Vol.13 No.-
In order to utilize waste FRP as lightweight aggregates, waste FRP was thermally decomposed in N2 and air atmospheres. Thermal analysis and ball milling of the decomposed FRP were carried out and the results were evaluated with respect to forming and foam structure of the aggregate. The decomposed FRP containing char and glass fiber was found to be milled with ease and formed into aggregate. Decomposition of FRP in N2 atmosphere resulted in a large amount of char, which remained during firing due to glassy phase formed. However, decomposition in air reduced the amount of char and resulted in foam structure with isolated pores and low density. The results of thermal analysis indicate that porous lightweight aggregates can be fabricated by controlling the amount of char and adding a foam agent.
Fe-30%Ni-0.25%C합금의 기계적 성질에 미치는 Ausforming처리 및 Marforming처리의 영향
朴豊玉,李圭福,金學信 全北大學校 1993 論文集 Vol.36 No.-
The effect of ausforming treatment and marforming treatment on the mechanical properties of Fe-30%Ni-0.25%C alloy was investigated. The results obtained in this paper are as follows ; 1) The strength of ausformed martensite was mainly increased because of work-hardening inherited from deformed austenite. The better ductility of ausformed martensite was due to ductile matrix formation of retained austenite and absense of transformed twin and high dislocation density. 2) The strength of marformed martensite was increased by the increment of dislocation density, crossing of transformed twin with deformed twin and the mutual crossing of deformed twin. 3) The ductility of marformed martensite was lower than that of ausformed martensite but the strength of marformed martensite was higher. From this result, marforming treatment is much better than ausforming treatment for the improvement of mechanical properties in Fe-30Ni-0.25%C alloy.
李豊憲,李揆鎭 홍익대학교 산업기술연구소 2002 産業技術 Vol.12 No.-
A ceramic coating of glass was deposited on a water supply steel pipe sample and its microstructure and chemical resistance were evaluated. Glass enamel coating was found to be relatively uniform over the substrate surface. However, a number of pin holes were observed due to the evolution of gases formed from the steel substrate. Iron oxide was present along with glass in the coating, as a result of oxidation of the substrate exposed by pin holes. The chemical resistance tests showed that the coating has less chemical resistance than industrial coating reported in the literature. This resulted from the chemical composition of the enamel glaze used in this study.
전동차용 흑연질 브러쉬 제조에 있어서 함침, 흑연화 조건에 관한 연구
李豊憲 홍익대학교 산업기술연구소 1997 産業技術 Vol.7 No.-
We have taken specimens with coal tar pitch 33% as binder and formation pressure 15㎏/㎠. The result of the volume density of these specimens were shown 1.45㎏/㎤ before sintering and 1.51g/㎤ after sintering at 1300℃. At first these sample were presented volume density 1.45g/㎤. porosity 25%, bending strength 384 ㎏/㎠. After several time impregration process using pitch, however, these specimens were shown optimum physical properties with increasing of volume density 1.76g/㎤, porosity 3.8%.
李豊憲 弘益大學校 産業技術硏究所 2005 産業技術 Vol.15 No.-
Powders of Ni hydroxide-coated YSZ and Ni precipitate were prepared and crystal growth of NiO in the powders was investigated. The crystallization of NiO from Ni hydroxide was retarded on YSZ surfaces and occurred at higher temperature than that on Ni precipitate powder. NiO crystallite on the Ni precipitate powder grew rapidly without any constraint as the calcination temperature increased, resulting in ~100 ㎚ size at 800℃. However, growth of NiO crystallite on the YSZ surface was significantly retarded and resulted only in ~30 ㎚ size at 800℃.