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Poly(ether-block-amide)/GPTMS 하이브리드 분리막을 이용한 이산화탄소와 메탄의 투과특성
이근철 ( Keun Chul Lee ),김현준 ( Hyunjoon Kim ) 한국화학공학회 2016 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.54 No.5
Poly(ether-block-amide)(PEBAX®) resin is a thermoplastic elastomer combining linear chains of hard-rigid polyamide block interspaced soft-flexible polyether block. It was believed that the hard polyamide block provides the mechanical strength and permselectivity, whereas gas transport occurs primarily through the soft polyether block. The objective of this work was to investigate the gas permeation properties of carbon dioxide and methane for PEBAX®-1657 membrane, and compare with those obtained for other grade of pure PEBAX®, PEBAX®-2533 and PEBAX® based hybrid membranes. The hybrid membranes based PEBAX® were obtained by a sol-gel process using GPTMS ((3 glycidoxypropyl) trimethoxysilane) as the only inorganic precursor. Molecular structure and morphology of membrane were analyzed by 29Si-NMR, DSC and SEM. PEBAX®-2533 membrane exhibited higher gas permeability coefficients than PEBA ®-1657 membrane. This was explained by the increase of chain mobility. In contrast, ideal separation factor of CO2/CH4 for PEBAX®-1657 membrane was higher than PEBAX®-2533 membrane. It was explained by the decrease of diffusion selectivity caused by increase of chain mobility. For PEBAX®/GPTMS hybrid membrane, gas permeability coefficients were decreased with reaction time. Gas permeability coefficient of CH4 was more significantly decreased than CO2. It can be explained by the reduction of chain mobility caused by the sol-gel process, and strong affinity of PEO segment with CO2. Comparing with pure PEBAX®-1657 membrane, ideal separation factor of CO2/CH4 for PEBAX®/GPTMS hybrid membrane has decreased to 4.5%, and gas permeability coefficient of CO2 has increased 3.5 times.
등산활동에 참여하는 중년기 성인의 인지된 자유감과 자아실현, 삶의 질의 관계
이근철 ( Keun Chul Lee ),전현수 ( Hyun Soo Jeon ) 한국스포츠심리학회 2014 한국스포츠심리학회지 Vol.25 No.4
Purpose: Therefore, social desirability, one of common method biases, influenced the research model. This study is intended to verify the mediation effect of self-actualization in the influential relationship between quality of life and the perceived sense of freedom of middle-aged adults participating in the mountain climbing activity. Method: In order to carry out this study, 289 male and female adults who reached the top of mount K were selected through random sampling. In order to analyze data, we carried out descriptive statistics, confirmatory factor analysis, correlation test, structural equation modeling analysis, and multi-group confirmatory factor analysis. Result: In the analysis results, correlation among all variables was shown. And it was shown that middle-aged adults`` self-actualization full mediated relationship between perceived sense of freedom and quality of life. In the measurement invariance test results, the goodness-of-fit of model according to gender and age was tested. Therefore, research participants`` cross validation was ensured with regard to measurement instrument. Conclusion: Through these results, in case of middle-aged adults who participated in the mountain climbing activity, it was verified that a leisure activity selected by themselves had an effect on the quality of life through self-actualization.
멀티데이타베이스 환경에서 사이트간 통신비용을 줄이기 위한 효율적인 조인 메소드
이근철(Keun-Chul Lee),김지운(Kang-Sik Moon),문강식(Ji-Woon Kim),이전영(Jeon-Young Lee) 한국정보과학회 1997 한국정보과학회 학술발표논문집 Vol.24 No.2Ⅰ
멀티데이타베이스 시스템은 다양한 유형의 정보시스템을 통합하여 사용자에게 단일화 형태의 데이타베이스 서비스를 제공하는 시스템이다. 멀티데이타베이스 환경에서 사용자 질의를 처리하기 위해서는 분산된 정보 소스들에 대한 사이트간 조인과정을 필수적이며, 사이트간 조인 수행시 성능에 결정적인 역할을 하는 것은 네트워크상에서 전송되는 데이터의 양일 것이다. 본 논문에서는 사이트간 조인시 통신량을 줄이기 위해 기존 세미조인을 변형한 새로운 방식을 제안한다. 기본적인 아이디어는 세미조인에 필요한 릴레이션의 속성들을 모두 최종 결과를 생성하는 사이트로 전달하는 것이 아니라, 이들 릴레이션의 조인에 필요한 매칭정보를 생성하고 이 정보와 실제 조인될 속성들만을 전달하는 것이다. 세미조인시 각 릴레이션간 사전 매칭정보는 튜플당 1비트를 차지하는 비트벡터로 표현되고, 최종 결과를 산출하는 사이트에서는 이 비트벡터를 이용, 소모적인 조인 방식이 아닌 머지(merge) 방식을 사용한다. 따라서 기존의 방식에 비해 네트워크를 타는 데이타 량을 현저히 줄여주고, 최종 산출하는 사이트의 지역 부하도 줄여주게 된다.