침상형 α - Goethite 를 분산시킨 현탁기포탑에서의 기포경과 물질전달계수 ( 2 )

고재천,김범식,김철웅,이정민,이보성 ( Jae Cheon Koh,Beom Sik Kim,Chulung Kim,Jung Min Lee,Bosung Rhee ) 한국화학공학회 1992 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.30 No.1

Mass transfer phenomena were studied in a studied bubble column in which fine acicular α-Goethite particles(average length 0.27 ㎛) were suspended in 1N-NaOH solution. In order to measure bubble diameter, two-point probe was used. Distribution of measured bubble diameters in the slurry bubble column was showed log-normal and changed from unimodal to multimodal with increasing the superficial gas velocity and solid concentration. Sauter mean bubble diameter(d_(vs), volume-to-surface mean bubble diameter) was minimized at transition region, but above that region, it was increased by increasing superficial gas velocity and solid concentrations. Liquid side mass transfer coefficient(k_L) was increased below 0.9 wt% solid concentration but was suddenly decreased above 0.9 wt% by concentrating the solid. The k_L was also increased with increasing the Sauter mean bubble diameter. Liquid side mass transfer coefficient can be represented as following equation by dimensionless groups and wt% concentration on this system and conditions. Sh =1.0×10^(-5)Sc^(1.53)Re^(0.79)Bo^(0.51)/(1+8.×Ф^(2.73))

초등교사의 수행평가에 대한 학생들의 대응

고재천 ( Jae Cheon Koh ) 한국아동교육학회 2006 아동교육 Vol.15 No.3

초등교사의 전문성 탐색

고재천(Jae Cheon Koh) 한국초등교육학회 2001 초등교육연구 Vol.14 No.2

The purpose of this study was to examine the professionalism of the elementary school teachers on the basis of the nature and characteristics of elementary education. The literature analysis identified the characteristics of elementary education by the five aspects of educational processes. And then, this study explored the professionalism of the elementary school teachers on the basis of those characteristics. The five characteristics of elementary education examined were integrative education, whole-child education, basic and fundamental education, common and general education, and free and compulsory education. Teaching in the elementary school level is characterized as a profession in the normative aspects, but it is difficult to say so in the practical aspects. The professionalism of the elementary school teachers in the normative aspects was identified as follows; First, the elementary school teacher should be the professional who has the integrative view on elementary education. Second, the elementary school teacher should be the professional who behaves as a model to form a whole-child. Third, the elementary school teacher should be the professional who teaches all subject matters in an elementary school. Fourth, the elementary school teacher should be the professional who instructs children with a proper way in an elementary level. Lastly, the elementary school teacher should be the professional who possesses, as a practicer, the consciousness of mission and servicemanship in his/her occupation. After all, it is important that the problem on approving the professionalism of the elementary school teacher depends on how teacher`s professionalism can be actualized in the classroom settings.

NiCuZn Ferrite 분말제조에 있어서 Ball Mill 분쇄 공정 중에 혼입되는 불순물의 함량

고재천(Jae-Cheon Koh),류병환(Beyong-Hwan Ryu) 한국자기학회 1999 韓國磁氣學會誌 Vol.9 No.4

The pick up impurity was studied for preparing the NiCuZn ferrite powder by a ball milling method that usually uses in the industrial ceramic process. The raw materials of NiO, CuO, ZnO, and Fe₂O₃ powder were weighted according to various spinel composition and mixed for 18 hrs by a wet ball milling method after that the slurry was followed by spray dried and calcined at 700 ℃ 3 hrs. The calcined NCZF powder was finally ball milled during 65 hrs as same method. The stainless steel ball and jar are used as mixing and milling equipment and the solid concentration of the slurry was 25 vol%. The impurities, stainless steel pickup, were effected by the composition of raw materials especially iron oxide, nickel oxide in the mixing process and by the rate of calcine of NiCuZn ferrite in final milling process. The empirical equation of stainless steel pickup was driven in the wet ball milling system. Finally, the composition of NiCuZn ferrite could be controlled by the empirical equation.

교사 효과성의 개념적 의미 탐색

고재천 ( Jae Cheon Koh ) 한국아동교육학회 2008 아동교육 Vol.17 No.2

예비 초등교사가 인식한 수업실습활동의 저해요인 탐색

고재천(Koh, Jae Cheon) 학습자중심교과교육학회 2018 학습자중심교과교육연구 Vol.18 No.2

이 연구는 예비 초등교사들이 인식한 수업실습활동의 저해요인이 무엇인지 개념도 방법을 사용하여 탐색하였다. 교육대학교 4학년 학생 26명을 대상으로 2017년 3월부터 12월말까지 약 10개월에 걸쳐 면담을 통하여 진술문 목록을 개발하고 이를 평정하여 다차원척도분석과 군집분석을 실시하여 개념도를 완성하였다. 연구 결과는 첫째, 예비 초등교사들은 수업실습활동의 저해요인을 실습지도 및 실습지원과 수업운영 및 실습조건의 두 가지 차원에서 인식하였다. 둘째, 예비 초등교사들이 인식한 수업실습활동의 저해요인은 모두 4개 요인으로 나타났다. 셋째, 예비 초등교사들이 인식한 수업실습활동의 저해요인들에 대한 중요성은 군집별로 큰 차이는 없었으나, 실습지도안작성 및 시연의 부담 군집과 실습 운영의 부실 군집이 상대적으로 높게 평가되었다. 연구의 결론은 첫째, 예비 초등교사들은 운영 및 조건 차원과 지도 및 지원 차원을 동시에 고려하여 실습지도안 작성 및 시연의 부담, 실습 운영의 부실, 실습 환경의 열악, 실습지도 여건 및 자료의 부족 등을 수업실습활동의 저해요인으로 인식하였음을 알수 있다. 둘째, 예비 초등교사들은 수업실습활동의 저해요인으로 실습지도안 작성 및 시연의 부담이나 실습 운영의 부실과 같은 수업운영 요인을 보다 더 중요한 요인으로 인식하였음을 알 수 있다. 셋째, 이 연구가 예비 초등교사들이 인식한 수업실습활동의 저해요인에 대한 개념적 구조를 밝혀 줌으로써 수업실습활동 관련 이론의 정립과 관련 정책 및 프로그램의 개발에 활용될 수 있을 것이다. This study used concept mapping methods to explore the factors that student-teachers perceive inhibit class practices in the primary school. 26 student-teachers were interviewed and the collected ideas were reduced to 45 statements from March to December 2017. Using multidimensional scaling and cluster analysis, we were able to subtract from a two-dimensional 4-cluster concept map. The results were as follows: First, student-teachers perceived the inhibitory factors as instruction-support dimension and operation-condition dimension. Second, 4 clusters were deducted from the factors that inhibit class practices: the burden of preparing a lesson plan and class performance, failure of practice, poor practice environment, and lack of practice guidance and materials. Third, the ratings from the 4 clusters revealed that the average of each cluster did not differ significantly from the others. But, student-teachers perceived operation dimension factors as more important than conditional dimension factors. The conclusions were as follows: First, 4 inhibitory class practice factors perceived by student-teachers were depended on two dimensions. Second, student-teachers perceived the burden of preparing a lesson plan and class performance as the most important factors.

초등학교 교사가 인식한 수업 자율성의 구성 요인 탐색

고재천(Koh, Jae Cheon) 학습자중심교과교육학회 2019 학습자중심교과교육연구 Vol.19 No.2

이 연구는 초등학교 교사들이 인식한 수업 자율성의 구성 요인이 무엇인지 개념도 방법을 사용하여 탐색하였다. 광주와 전남 지역 초등학교에 근무하는 초등학교 교사 25명을 대상으로 2018년 1월부터 10월까지 약 10개월 동안 면담과 질문지를 통해 43개의 최종진술문을 개발 및 평정하고 다차원척도분석과 군집분석을 실시하여 개념도를 작성하였다. 이 연구의 결과는 첫째, 초등학교 교사들이 인식한 수업 자율성의 구성 요인은 수업-수업외 활동과 학급내부-학급외부 활동의 두 개 차원에 의해서 ‘교수활동의 결정’, ‘전문성의 발휘’, ‘교육내용의 선택’, ‘학급업무의 처리’, ‘수업 관련 주변요구의 판단’의 5개 군집으로 나타났다. 둘째, 초등학교 교사들이 인식한 수업 자율성을 구성하는 요인들의 중요성은 군집별로 큰 차이는 없었으나, ‘교수활동의 결정’, ‘전문성의 발휘’, ‘교육내용의 선택’, ‘학급업무의 처리’, ‘수업관련 주변요구의 판단’의 순이었다. 이 연구의 결론은 첫째, 초등학교 교사들은 수업 자율성의 구성 요인에 대하여 수업 자율성이 요구되는 교육 활동과 수업 자율성이 발휘되는 공간을 동시에 고려하고 있음을 알 수 있었다. 둘째, 초등학교 교사들이 인식하는 수 업 자율성을 구성하는 중요한 요인은 수업과 직접 관련되는 것들로서 수업 내용과 방법의 선택 및 결정과 그리고 전문성의 발휘라는 사실을 알 수 있었다. This study used concept mapping methods to explore the factors that primary school teachers perceive to construct the teaching autonomy. 25 primary school teachers were interviewed and the collected ideas were reduced to 43 statements from January 2018 to October 2018. Using multidimensional scaling and cluster analysis, a two-dimensional 5-cluster concept map was created. The results were as follows: First, primary school teachers perceived the construct factors of teaching autonomy as the 5 clusters and 2 dimensions. 2 dimensions were inside-outside classroom level and inside-outside class activities level. 5 clusters were ‘decision of teaching activities’, ‘demonstration of instructional professionalism’, ‘selection of class contents’, ‘treatment of class works’, and ‘judgment of class surrounding needs’. Second, the ratings from the 5 clusters revealed that the average of each cluster did not differ significantly from the others. The conclusions were as follows: First, it was found that primary school teachers were simultaneously considering both classroom activities and class spaces to identify the conceptual structure of the construct factors of teaching autonomy. Second, it was found that the most important factors that construct the teaching autonomy recognized by primary school teachers were things that are directly related to the class. Third, this study can be applied to the theoretical understanding and program development about teaching autonomy.

초등학교 실습지도교사가 인식한 수업실습 지도의 제약요인 탐색

고재천(Koh Jae Cheon) 학습자중심교과교육학회 2017 학습자중심교과교육연구 Vol.17 No.2

이 연구는 초등학교 실습지도교사들이 인식하는 수업실습 지도의 제약요인이 무엇인지 탐색하는데 있다. 연구문제는 초등학교 실습지도교사들이 인식하는 수업실습 지도의 제약요인에 대한 개념적 구조와 중요도는 어떠한가이다. 이를 위해 G 교육대학교 실습협력 초등학교에 근무하는 실습지도교사 20명을 대상으로 개념도 연구방법을 통해 자료를 수집하고 분석하였다. 이 연구 결과는 첫째, 초등학교 실습지도교사들은 수업실습 지도의 제약요인을 지도-환경과 교사-학생의 두 차원으로 인식하였다. 둘째, 초등학교 실습지도교사들이 인식하는 수업실습 지도의 제약요인은 5개의 군집으로 나타났으며, 지도 여건의 미흡, 실습 환경의 열악, 실습 능력과 의욕의 부족, 지도 역량과 사명감의 부족, 지도 역할 수행의 저조이었다. 셋째, 초등학교 실습지도교사들이 인식하는 수업실습 지도의 제약요인에 대한 중요성은 군집별로 큰 차이는 없었으나, 지도 여건의 미흡 요인이 다소 높게 평가된 반면에 지도 역량과 사명감의 부족 요인과 실습지도 역할수행 저조 요인이 상대적으로 낮게 평가되었다. 이 연구의 결론은 첫째, 초등학교 수업실습 지도의 제약요인은 실습지도교사 및 실습생 요인과 실습지도 및 환경 요인이라는 것을 알 수 있다. 둘째, 초등학교 수업실습 지도를 제약하는 중요한 요인은 지도 역량과 사명감의 부족이나 역할 수행의 저조가 아니라 지도 여건의 미흡이라는 것을 알 수 있다. 이 연구가 초등학교 실습지도 교사가 인식하는 수업실습 지도의 제약요인에 대한 개념적 구조를 밝혀 줌으로써 수업실습지도 관련 이론의 정립과 관련 정책 및 프로그램 개발에 활용될 수 있을 것이다. This study used concept mapping methods to explore the constraint factors that teacher educators perceive teaching student-teachers in the primary school. 20 teacher educators were interviewed and the collected ideas were reduced to 50 statements. Using multidimensional scaling and cluster analysis, we were able to subtract from a two-dimensional 5-cluster concept map. The results were as follows: First, teacher educators perceived the constraint factors as instruction-environment dimension and teacher-student dimension. Second, 5 clusters were deducted from the factors that constrain teaching student-teachers: inadequate training environment of teacher educators, lack of training conditions of student-teachers, lack of practical ability and motivation of student-teachers, lack of practical guidance and competence of teacher educators, and poor performance of practical guidance role of teacher educators. Third, the ratings from the 5 clusters revealed that the average of each cluster did not differ significantly from the others. The conclusions were as follows: First, the factors that constrain teaching student-teachers are teacher educator factors and student-teacher factors. Second, the important factors that constrain teaching student-teachers are not lack of practical guidance and competence and poor role performance of teacher educators but inadequate training environment of teacher educators.

SiCl4 - ( CH3 )2 SiCl2 , SiCl4 - CH3SiCl3 , SiCl4 - ( CH3 )3 SiCl 계의 등온 기액평형에 관한 연구 ( 1 )

김철웅,고재천,이정민 ( Chulung Kim,Jae Cheon Koh,Jung Min Lee ) 한국화학공학회 1993 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.31 No.2

Isothermal vapor-liquid equilibria have been determined for SiCl₄-Me₂SiCl₂, SiCl₄-MeSiCl₃ and SiCl₄-Me₃SiCl₃at 50℃ using headspace gas chromatography as static method. The system SiCl₄-Me₃SiCl forms an azeotropic mixture, while the other two systems did not have the azeotrope. The obtained results were correlated to the Wilson, Van Larr, Margules, NRTL equations. These experimental vapor-liquid equilibrium data for binary systems of methychlorosilanes are presented as the basic data of separation process.

전이 금속 산화물이 담지된 La / Al 복합산화물 촉매상에서의 메탄 연소반응

서정권,하백현,고재천,이정민 ( Jeong Kwon Suh,Baik Hyon Ha,Jae Cheon Koh,Jung Min Lee ) 한국화학공학회 1993 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.31 No.6

Combustion catalysts were prepared by the impregnation of transition metal oxide on La/Al oxide(Al₂O₃/La₂O₃=19), and then calcined in air. Methane combustion was carried out using these catalysts. X-ray diffraction analysis indicates that La/Al oxide was crystallized from amorphous form into La-β-Al₂O₃ phase above 1200℃. Crystallization was accelerated by the addition of copper on La/Al oxide, but it was retarded by the addition of chromium on La/Al oxide. The copper content of the surface of CuO-La/Al oxide decreased as the calcination temperature increased. This result indicates the formation of solid solution. In case of Cr₂O₃-La/Al oxide, Cr₂O₃mainly existed on the catalyst surface. The activities of catalysts calcined at 1200℃ appeared as the following order; CuO, Cr₂O₃>Fe₂O₃>MnO>CoO>NiO. The catalytic activity of CuO-La/Al oxide decreased as the calcination temperature increased. However the catalytic activity of Cr₂O₃-La/Al oxide was still maintained after calcination at 1400℃.