Bi_1/2Na_1/2TiO₃-BiAlO₃ 무연 압전 세라믹스의 유전 및 전기 기계적 변형 특성에 대한 SrTiO₃ 첨가 효과

이상섭,이창헌,즈엉 짱 안,김동혁,김병우,한형수,이재신,Lee, Sang Sub,Lee, Chang-Heon,Duong, Trang An,Kim, Dong Hyeok,Kim, Byeong Woo,Han, Hyoung-Su,Lee, Jae-Shin 한국재료학회 2021 한국재료학회지 Vol.31 No.10

(Bi_1/2Na_1/2)TiO₃ (BNT)-based ceramics are considered promising candidates for actuator application owing to their excellent electromechanical strain properties However, to obtain large strain properties, there remain several issues such as thermal stability and high operating fields. Therefore, this study investigates a reduction of operating field in (0.98-x)Bi_1/2Na_1/2TiO₃-0.02 BiAlO₃-xSrTiO₃ (BNT-2BA-100xST, x = 0.20, 0.21, 0.22, 0.23, and 0.24) via analyses of the microstructure, crystal structure, dielectric, polarization, ferroelectric and electromechanical strain properties. The average grain size of BNT-${\underline{2}}$BA-100xST ceramics decreases with increasing ST content. Results of polarization and electromechanical strain properties indicate that a ferroelectric to relaxor state transition is induced by ST modification. As a consequence, a large electromechanical strain of 592 pm/V is obtained at a relatively low electric field of 4 kV/mm in 22 mol% ST-modified BNT-2BA ceramics. We believe that the materials synthesized in this study are promising candidates for actuator applications.

Bi_0.5Na_0.5TiO₃-BiFeO₃-SrTiO₃ 삼성분계 무연 압전 세라믹스의 강유전체-완화형 강유전체 상전이 거동

이상섭,이창헌,즈엉 짱 안,웬 호앙 티엔 코이,한형수,이재신,Lee, Sang Sub,Lee, Chang-Heon,Duong, Trang An,Nguyen, Hoang Thien Khoi,Han, Hyoung-Su,Lee, Jae-Shin 한국전기전자재료학회 2021 전기전자재료학회논문지 Vol.34 No.1

This study investigated the structural, dielectric, ferroelectric, and strain properties of (0.98-x)Bi1/2Na1/2TiO3-0.02BiFeO3-xSrTiO3 (BNT-BF-100xST, x＝0.20, 0.22, 0.24, 0.26, and 0.28). All samples were successfully synthesized using the conventional solid-state reaction method and sintered at 1,175℃ for 2 h. The average grain size of the BNT-BF-100x ceramics decreased with increasing ST content. Furthermore, we observed that the ferroelectric- relaxor transition temperature (TF-R) decreased with increasing ST content, which eventually vanished in the BNT-BF-24ST ceramics. The results indicated that a ferroelectric to relaxor phase transition could be induced by ST modification. Consequently, a large electromechanical strain of 633 pm/V at 4 kV/mm was observed for the BNT-BF-26ST ceramics. These results imply that our materials have the competitive advantage of larger strain under lower operating field conditions compared with other BNT-based lead-free piezoelectric ceramics. We expect that BNT-BF-ST lead-free piezoelectric ceramics are promising candidates as a novel ternary BNT-based system and can find potential applications in actuators.

체육수업에 대한 교과 흥미도가 학생들의 학업열의에 미치는 영향

이상섭(Lee, Sang-Sub),조홍식(Cho, Hong-Sik) 한국체육과학회 2015 한국체육과학회지 Vol.24 No.1

The purpose of this study was to investigate the effects of subject interest in physical education classes on academic engagement among students. For that purpose, the investigator found the population in middle and high school students in Gyeonggi Province and sampled 420 students through convenience sampling. Collected data were put to multiple regression analysis with the PASW Version 18 .0 statistical program. The findings were as follows: First, all the sub-factors of subject interest in physical education classes had statistically significant effects on academic engagement(efficacy). Second, all the sub-factors of subject interest in physical education classes had statistically significant effects on academic engagement(commitment) . Third, all the sub-factors of subject interest in physical education classes had statistically significant effects on academic engagement (vitality). Finally, all the sub-factors of subject interest in physical education classes had statistically significant effects on academic engagement (absorption)

체육수업에 대한 교과 흥미도가 학생들의 기본적 심리욕구에 미치는 영향

이종철(Lee, Jong-Chul),이상섭(Lee, Sang-Sub) 한국체육과학회 2011 한국체육과학회지 Vol.20 No.6

The purpose of this study is to identify effects of subject interest in physical education on basic psychological desires of students. For doing this, the authors established the students in middle and high schools in Gyeonggi Province as the population, selecting 340 students by using convenience sampling. The collected data was conducted of multiple regression analysis by using the PASW Ver 18.0 statistic program, and the results are as follows. First, the subject interest in physical education had statistically significant effects on the basic psychological desires of the students(competence), but among the sub-factors, teacher preference factors did not have significant effects on the basic psychological desires(competence). Second, all the sub-factors of the subject interest in physical education(teacher preference, subject content, values & efforts, and subject competence) had statistically significant effects on the basic psychological desires of the students(relation). Third, the subject interest in physical education had statistically significant effects on the basic psychological desires of the students(autonomy), but among the sub-factors, teacher preference factors did not have significant effects on the basic psychological desires(autonomy).

체육수업의 재미요인이 학생들의 심리적 유인성향에 미치는 영향

이종철(Lee Jong-Chul),조홍식(Cho Hong-Sik),박윤혁(Park Yoon-Hyuk),이상섭(Lee Sang-Sub) 한국체육과학회 2006 한국체육과학회지 Vol.15 No.3

The purpose of this study was to explore ways to at identifying what factors made students felt enjoyment during physical education class and how much those factors influence on psychological of inducement inclination. To this end, Cluster Random Sampling was used to set up the population with boys and girls middle school students in Kyunggi-do and Inchon-si area. The survey tool was questionnaire and Collected data hereof were analyzed by one way ANOVA analysis and Multiple Regression Analysis with SPSS WIN Ver 11.5. The aforementioned method and procedure led this research to the conclusion as follows. Firstly, out of sub-factors of physical education class enyoyment by middle schoolers' individual characteristics(gender, result), boy students showed more than girl students, in which there were statistically significant difference. Meanwhile, statistically significant difference was not found in free time, explanation and modeling. Secondly, out of sub-factors of psychological of inducement inclination by middle schoolers' individual characteristics(gender, result), boy students' response was higher in senses of confidence, enthusiasm, accomplishment and indulgence than girl students' in which all considers appeared. Thirdly, the effect enjoymant factors of physical education class had statistically significant on sub-factors of psychological of inducement inclination senses of confidence, enthusiasm, accomplishment and indulgence, free time that is a sub-factor of enjoymant which did not had statistically significant influenced on sense of accomplishment.

체육교사의 자율성 지지와 학생들의 교과 흥미도 및 수업참여와의 구조적 관계

이상섭(Lee, Sang-Sub),조홍식(Cho, Hong-Sik) 한국체육과학회 2013 한국체육과학회지 Vol.22 No.3

The purpose of this study was to examine substantially structural relations between physical educator’s autonomy support, subject interest and Class Participation in physical education class. The subjects of this study were 450 middle and high school students in Gyeonggi Province, sampled by convenience sampling. The data was applied of confirmatory factor analysis and structural equation model(SEM) analysis by using the PASW Ver 18.0 and the AMOS 18.0. Based on the results, First, for individual consideration of physical educator’s autonomy support appeared to have significant influence to the subject interest. Second, for individual consideration of subject interest appeared to have significant influence to the Class Participation. Third, the physical educator’s autonomy support variables appeared to have significant influence to the academic engagement. Fourth, indicated that subject interest mediated the relationship between physical educator’s autonomy support and Class Participation in physical education class.

소화용 마이크로캡슐을 함유한 소화 벽지의 개발

이상섭(Sang-Sub Lee),김창홍(Chang-Hong Kim),김민철(Min-Chul Kim),김종상(Jong-Sang Kim) 한국화재소방학회 2020 한국화재소방학회논문지 Vol.34 No.6

최근의 화재 사건들을 보면 노래방, 고시원 같은 좁고 밀폐된 공간에서의 화재만이 아니라 목욕탕, 물류창고 등넓은 공간에서의 화재가 발생하며, 특히 좁은 공간에서의 화재는 벽지를 통해 급격한 화재 확산과 그로 인해 발생하는 대량의 유독가스로 인해 골든타임이 단축되고, 현장에서 대피하지 못해 많은 인명피해가 일어나고 있다. 이에 대한 대책으로 불에 잘 타지 않는 방염성을 부여한 다양한 벽지가 개발되고 있지만, 방염 성분이 일반 벽지보다 5배이상의 CO를 배출해 더 심각한 인명피해를 초래할 수 있다. 본 연구에서는 불길 확산의 주원인인 벽지에 소화 성능을 함유시켜 화재 발생 시 대피 시간 증가 및 불길 확산 억제의 효과를 기대하는 소화 벽지를 개발했다. 일반 물풀에소화용 마이크로 소화 캡슐을 함유해 일반 벽지의 전소 시간을 2 min에서 5 min으로 증가함을 확인했으며, 벽지 뒷면에 마이크로 소화 캡슐을 점착제 형태로 부착 후 전소 Test 및 45° 난연 시험에서 소화 유효성을 확인했으며, 열중량 분석(TGA)를 통해 반응 시작온도, Peak point, 반응 종료 온도 및 중량감소율을 확인하여 접착성 필름의 열적 특성을 확인하였으며, 시중의 방염 벽지와의 연기밀도를 비교해 유의한 결과를 얻을 수 있었다. In this study, a wallpaper with fire-extinguishing properties was developed. This wallpaper is expected to increase theevacuation time and suppress the spread of flames in case of fire. It was confirmed that the fire-extinguishing time of anordinary wallpaper can be increased from 2 to 5 min by incorporating micro-extinguishing capsules in the general waterpool. After attaching microfire-extinguishing capsules in the form of a film on the back of the wallpaper, a burning testusing a torch and 45° flame retardant digestion was performed, and the thermal properties of the adhesive film were verifiedbased on the reaction start temperature, peak point, reaction end temperature, and weight reduction rate throughthermogravimetric analysis.

개인 웹 에이전트를 위한 사용자 프로파일 구축

이상섭(Sang-Sub Lee),소영준(Young-Jun So),박영택(Young-Tack Park) 한국정보과학회 1998 한국정보과학회 학술발표논문집 Vol.25 No.2Ⅱ

본 논문에서 구현하고자 하는 웹기반 사용자별 에이전트는 웹을 이용해 정보를 검색하는 사용자들에 대한 사용자 관심도를 사용자의 웹검색 행위를 감시하는 모니터 에이전트에 사용자가 직접 기술하게 하고 이를 별도의 학습서버를 두어 사용자별 프로파일을 만들어 이를 사용자가 확인 및 편집할 수 있게 하였다. 서버에서의 학습 과정은 웹 브라우저를 통하여 수집된 정보를 바탕으로 사용자가 관심을 가지는 웹 문서의 일반적인 내용에 대한 관심 정확도를 높이는 일련의 단어 정제 과정을 통하여 최적의 관심 키워드를 추출하는 작업으로 이루어지며 이는 표현 모델인 사용자 프로파일을 구축하여, 관심 문서를 검색하는데 적절한 정보를 제시하는 것을 목적으로 한다. 이 시스템에서 적용되는 학습 방식은 사용자의 웹 문서 관심도에 의존하므로 웹 문서에 나타나는 텍스트들을 대상으로 C4.5 학습 시스템을 적용한다.

대학생들의 교양체육수업의 재미요인과 운동행동변화과정에 따른 운동행동변화단계

이상섭(Lee Sang-Sub),김형석(Kim Hyung-Suk) 한국체육과학회 2009 한국체육과학회지 Vol.18 No.1

This study was a close examination on the relationship between the general sports classes enjoyment sources. process of change and the stages of change in sports between college students. To do this, 334 case studies were used as the research subject in plain sample methods from the random sample methods from 5 universities in the Seoul and Kyongi region. The methods used for the statistics result was SPSS 12.0 using frequency analysis, factor analysis, correlation analysis, multiple regression analysis, MAOVA, and discriminant analysis. The results of the analysis were summarized as follows. first, the enjoyment sources from the college student came from improvement or experience of sport, freedom of sports, ability though experience and the process of change in sports showed as having a beneficial effect through positive. Second, the general sports classes college students change of knowledge, change of action, improvement or experience of sport, freedom of sports, ability though experience and the process of change in sports showed as having a beneficial effect through positive. Third, distinguishing the general sports class college students change of action came though in change of action through sports and then improvement or experience of sport.

이동성 에이젼트 시스템의 구축 방법과 활용

이상섭(Sang-sub Lee),오재준(Jae-jun Oh),박영택(Young-Tack Park) 한국정보과학회 1997 한국정보과학회 학술발표논문집 Vol.24 No.2Ⅱ

이동성 에이젼트(Mobile Agent)는 네트웍을 이동하여 사용자가 부여한 태스크(Task)를 수행하는 소프트웨어를 말한다. 본 논문은 이동성 에이젼트(Mobile Agent)의 특징을 소개하고 이동성 에이젼트 시스템 (Mobile Agent System)을 각 구성요소로 세분하여 이들 각 요소들이 담당하는 역할을 정의하고, 이를 바탕으로 이동성 에이젼트의 구축과 서버의 기반한 이동성 계획수립에 대한 방안을 제시하고자 한다.