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이경환,Lee, Gyeong-Hwan 한국과학기술단체총연합회 1986 과학과 기술 Vol.19 No.10
이 글은 지난 1985년 9월부터 1986년 3월까지 6개월간 한국과학재단의 지원을 받아 「지적소유권의 세계 동향과 대응전략에 관한 연구」라는 제목으로 한국 소프트웨어개발 연구조합 연구팀인 이경환(연구책임자) 교수외 6명의 연구자들이 연구한 결과보고 내용의 일부이다. <편집자 주>
이경환,서정철,차헌주,송교신,최준모 대한상하수도학회 2013 상하수도학회지 Vol.27 No.2
Sampling rate of Hydraulic pressure data, depending on the intended use of the water distribution system is an important factor. If sampling interval of hydraulic data is short, that will be more useful but it demand a lot of expense for maintenance. In this study, based on simulation of water distribution system 2 khz data, statistical techniques of student t distribution, non-exceedance probability using the optimal sampling rate for research.
이경환,고은정 서울시립대학교 도시과학연구원 2014 도시과학국제저널 Vol.18 No.3
The purpose of this study is to analyse the characteristics of neighbourhood environments affecting residents’ bicycle mode choice through a case study of Seoul. In this study, neighbourhood environments and other socio-demographic factors were used as explanatory variables in a causal model. The main data source used for this research was the 2006 Household Travel Survey, from which 214,978 observations were selected as the final sample. Statistical analysis was carried out by applying the random intercept logit model. The results of analysing the factors that affect the residents’ bicycle mode choice can be summarized as follows: first, the gender, income, occupation, vehicle ownership status, and residential type have statistically significant correlations with the bicycle mode choice. In addition, the travel time and travel distance affect the bicycle mode choice. Second, a high level of land use mix results in more bicycle travel. However, unlike what is shown in previous western studies, residential density does not have a significant correlation with bicycle travel. Third, the density of bicycle lanes has an effect on the bicycle mode choice, which shows that accessibility to bicycle lanes is an important planning factor in activating bike travel. Fourth, gradients are one of the important factors that affect the bicycle mode choice because residents use bicycles less in regions with steep slopes. Fifth, analysing the destination, like the origin, the land use mix, and bicycle lane density, was found to affect the bicycle mode choice.
상압소결법으로 제조한 Cu 입자 분산 Al<sub>2</sub>O<sub>3</sub> 나노복합재료의 미세조직 및 특성
이경환,오승탁,Lee, Kyong-Hwan,Oh, Sung-Tag 한국분말야금학회 2009 한국분말재료학회지 (KPMI) Vol.16 No.4
The pressureless sintering behavior of $Al_2O_3$/Cu powder mixtures, prepared from $Al_2O_3$/CuO and $Al_2O_3$/Cu-nitrate, has been investigated. Microstructural observation revealed that $Al_2O_3$ powders with nano-sized Cu particles could be synthesized by hydrogen reduction method. The specimens, pressureless-sintered at $1400^{\circ}C$ for 4 min using infrared heating furnace with the heating rate of $200^{\circ}C$/min, showed the relative density of above 90%. Maximum hardness of 16.1 GPa was obtained in $Al_2O_3$/MgO/Cu nanocomposites. The nanocomposites exhibited the enhanced fracture toughness of 4.3-5.7 $MPa{\cdot}m^{1/2}$, compared with monolithic $Al_2O_3$. The mechanical properties were discussed in terms of microstructural characteristics.