난삭재인 STD11 강의 정면밀링가공시 절삭특성에 관한 연구

김형석,문상돈,오성훈 전북대학교 공학연구원 ( 구 전북대학교 공업기술연구소 ) 2003 工學硏究 Vol.34 No.-

Wear and fracture mode of ceramic tool for hardened Std11 steel was investigated by face milling in this study. The cutting force and acoustic emission(AE) signal were utilized to detect the wear and fracture of ceramic tool. The following conclusions were obtained : (1) The wear and fracture modes of ceramic tool are characterized by the three types : ① wear which has normal wear and notch wear, ② wear caused by scooping on the rake face, ③ large fracture caused by thermal crack in the rake face. (2) The wear behaviour of ceramic tool can be detected by the increase of mean cutting force and the variation of the AE RMS voltage. (3) The catastrophic fracture of ceramic tool can be detected by the cutting force(Fz-component). (4) As the hardness of work material increased, acoustic emission RMS valve and mean cutting force(Fz) increased linearly, but the tool life decrease.

초등학교 과학수업에서 교사의 학습 동기 전략 분석

김동욱,이성숙,강대훈,백성혜 한국초등과학교육학회 2004 초등과학교육 Vol.23 No.1

The purpose of this study was to define teachers' learning motivation strategies and students' responses by analyzing science classes and interviews. The subjects were first grade and sixth grade teachers and students of an elementary school. The analysis tools are based on Keller's ARCS theory. The differences of teachers' motivation strategies were analyzed by grades and teachers' and students' backgrounds. The interviewers were composed of three teachers and three students of first grade, and three teachers and three students of sixth grade. The data were collected by recording of the classes using tape recorders, video cameras, and notebooks written by researchers. The results are as follows. First, teachers had their own styles of teaching strategies in their classes. Especially teachers' teaching backgrounds affected on the teachers' instructional strategies. The teachers who had long teaching experiences of lower grade students used to show a lot of attention strategies. While the teachers with long teaching experiences of higher grade students used to show few learning motivation strategies. Especially, sixth grade teachers used to show fewer confidence strategies than first grade teachers. Second, all of the teachers used to show few satisfaction strategies commonly in all the classes observed. Third, the students' recognition of the motivation strategies were not different according to their conceptions or activities of the classes. Commonly first grade students focused on the attention strategies, while sixth grade students focused on negative motivation strategies. Fourth, the teachers who believed that students need detail guidance and control recognized the needs of satisfaction strategies by students' autononmous activities after observing video tapes of other teachers' classes.

정면밀링 가공시 공구마모와 절삭특성에 관한 연구

吳晟勳,金太永 全北大學校 1994 論文集 Vol.38 No.-

In-process monitoring of cutting conditions and tool breakage is important improving automization of cutting machine tools. This study is concerned with monitoring of tool wear and cutting force in a milling operation. Tool wear can be detected by the characteristic value of maximum cutting force and cutting force RMS. The relations of cutting force characteristics and tool wear were investigated with experimental study in the machining of SUS304. The relationship between tool wear and cutting force characteristics were found in face milling operation.

화학 변화 개념에 대한 중학교 2학년 학생들의 선개념 조사 및 선개념 갈등상황 제시를 통한 개념변화 학습이론의 효과 분석

白盛惠,강대훈,金惠敬,蔡禹基,權鈞 한국교원대학교 과학교육연구소 1999 청람과학교육연구논총 Vol.9 No.1

본 연구에서는 중학교 2학년 학생들의 선개념을 조사하고, 개념변화 학습이론을 적용한 과학 수업을 제공함으로써 학습자의 학습 동기가 잘못된 선개념을 올바른 과학 개념으로 바꾸는데 어떠한 역할을 하는지 알아보았다. 이를 위하여 개념변화 학습이론에 근거한 수업을 받은 학습자의 선개념의 변화를 전통적인 수업을 받은 학습자의 선개념 변화와 비교하여 보았다. 연구 결과, 학생들은 중학교 1학년때 배운 물리 변화를 화학 변화의 개념과 혼동하여 화학 변화를 단순히 물리적 변화인 상태 변화로 인식하거나, 이와 관련된 잘못된 선개념들을 많이 가지고 있는 것으로 나타났다. 또한 화학 변화의 한 예인 연소 현상에 대해서는 초등학교 6학년부터 학습한 내용임에도 불구하고 눈에 보이지 않는 산소의 결합을 인식하지 못하였으며, 많은 문제의 상황에서 질량 보존의 법칙을 기계적으로 적용하는 특징도 보였다. 수업의 효과로는 개념변화 수업을 받은 학생들이 과학적 개념을 부분적으로 또는 완벽하게 이해를 한 비율은 50%를 넘지 못하였다. 그러나 이 비율은 교과서에 의존한 전통적인 수업을 받은 학생들의 과학적 개념 이해 비율인 39% 보다는 높은 비율이라고 할 수 있다. 개념변화 수업을 받은 학생들의 올바른 과학 개념 습득 비율이 전통적 수업을 받은 학생들의 비율보다 통계적으로 유의미하게 높은 것으로 나타났다. 따라서 본 연구에서 개발하여 실시한 개념변화 수업은 학습자의 올바른 과학 개념 습득에 효과적이라고 할 수 있다. Preconceptions of middle school students related to chemical change the students are surveyed. The students are divided into experimental group that are learned by concept change theory teaching model, and control group that are learned by traditional teaching method based on science textbooks. After the planned classes, the tendencies of concept change of the two groups according to students learning motivations are analyzed. New teaching methods, which based on concept change learning model and students learning motivations, developed by this research. And the effects of the new teaching method are testified. As a result, it is proved that most of the students have a lot of preconceptions, and persist the wrong conceptions after the classes. This tendency is same in the control group and in the experimental group.

급성충수돌기염으로 발현된 방선균증 2예

조진원,송진영,김창억,민영훈,최창순,우흥정,현인규,김종현,유기철,채승완,손진희 대한화학요법학회 2001 대한화학요법학회지 Vol.19 No.1

The Actinomyces species are normal flora of oral cavity and upper intestine characterized as gram-positive, non-spore-forming anaerobic or mjcroaerophilic rods. Actinomycosis is a chronic suppurative and granulomatous disease characterized by abscess, sinus, abundant granulation and mass. The appendix is the commonly involved site among abdominal actinomycosis. Abdominal actinomycosis is often difficult to diagnose before operation because of no reliable clinical features and infrequency of the disease. We report two cases of abdominal actinomycosis which were manifested as acute appendicitis. Those were detected Incidentally tv the pathologist after routine appendectomy. Both patients were successfully treated with appendectomy followed by proper antibiotics use.

화학과 생물 교과서에서 삼투 개념에 관한 설명 유형 분석

고영환,강대훈,박동조,김동욱,백성혜 한국과학교육학회 2002 한국과학교육학회지 Vol.22 No.4

이 연구에서는 고등학교와 대학교 화학과 생물 교과서에 제시된 삼투 개념에 대한 설명 유형 및 그림표현 유형을 분석하였다. 그리고 고등학교 화학Ⅱ 교과서와 생물Ⅱ교과서의 단원을 분석하였다. 분석 결과, 삼투현상에 대해서는 용매의 확산으로 설명하는 유형, 충돌로 설명하는 유형, 수화로 설명하는 유형, 농도의 평형으로 설명하는 유형 그리고 구멍을 막는 것으로 설명하는 유형 등 다섯 가지 유형으로 설명하고 있었다. 그리고 삼투 개념에 대한 설명 유형과 교과서에 제시된 그림 표현 유형 사이에 일치하지 않는 경우도 분석되었다. In this study, we analyzed types of explanation on osmosis concept that were represented in chemistry and biology textbooks of high school and college. There were 5 types of explanation on osmosis concept. The types of explanation were diffusion of solvent, collision, hydration, equilibrium of concentration and screen of holes. Last two types of explanation were classified into misconceptions. The various types of explanation on osmosis concept might cause to have be a reason that students had many misconceptions and to feel difficult to learn about osmosis concept. Many of textbooks is accord to types of concept explanation and figure explanation on osmosis but some is not

중학교 화학 분야의 개념 연구에 대한 문제점 분석

朴恩姬,姜대勳,白盛惠,朴國泰,金惠敬,蔡禹기,權鈞 한국교원대학교 과학교육연구소 1999 청람과학교육연구논총 Vol.9 No.1

중학교 화학 분야의 오개념 조사에 사용된 설문지의 문제점을 밝혀, 학생들의 정확한 오개념 조사를 위한 바탕을 마련하고자 한다. 기존의 중학교 화학 분야에 대한 오개념 조사 설문지가 연구 대상 학생들에게 잘못 사용되고 있었으며, 문항 내용 자체에도 오류가 있었음을 지적하고자 하는 것이다. 선행 연구들의 분석 결과들이 오개념이 아니라 무개념임을 확인하기 위하여 중학교 1학년 학생 182명을 대상으로 두 종류의 설문지 A와 B를 투입하여 조사하였다. 설문지 A는 오개념 연구를 위해 선행 연구들에서 사용한 문항들로 이루어진 것으로, 이를 투입한 결과를 선행 연구들의 결과들과 비교하기 위한 것이다. 그리고 설문지 B는 설문지 A에서 응답한 학생들의 구체적인 생각을 알아보기 위하여 새롭게 개발한 것이다. 설문지 A를 통해 얻은 결과와 선행 연구들에서 얻은 결과들을 비교할 때, 전반적으로 일관성이 없게 나타났으며, 중학교 1학년 학생들의 주관식 정답률이 객관식 정답률에 비해 매우 낮게 나타나는 공통점은 있었으나, 문항 자체의 오류들이 발견되었다. 설문지 B를 통해 학생들의 생각을 알아본 결과, 설문지 A에서 과학적 개념과 오개념으로 분류된 학생들 중에서 무개념으로 판단된 경우가 많았다. This study was to clarify the problems of questionnaires related to misconception researches of middle school chemistry and to prepare a ground for the correct misconception research for students. For these purposes, the questionnaires of the misconception researches related to chemistry in middle school were analyzed, and the mistakes of the questions which were used in 7th grade students were found, based on a definition of misconceptions in this study. Also, the errors in contents of the questionnaires were indicated. The results of the analysis revealed that most of the 7th grade students did not have misconceptions contrary to some of the previous researches conclusions. They only had no conceptions related to the contents. In order to support this analysis, two different questionnaire sets (questionnaire set A and B) for 182 7th grade students were used. After obtaining similar results to those of the previous researches by the questionnaire set A, the students' thoughts were examined by the questionnaire set B. From the results of this study, the correct answer rates of subjective questions were very low compared with those of objective questions in the questionnaire set A for 7th grade students. It was hard to find consistency among the results of the researches using the questionnaire set A. And many contents of the questions consisted of the questionnaire set A were not consisted with a definition of misconceptions. There were errors in the contents of the questions, too. The students classified as the having-science-concepts group and the having-misconceptions group by the questionnaire set A were classified as the having-no-concepts group by the questionnaire set B.

증기상 Beckmann 전이 반응에 대한 Aluminophosphate 분자체의 촉매 특성

윤영삼,박판욱,권성헌,김병주 釜山大學校生産技術硏究所 1997 生産技術硏究所論文集 Vol.53 No.-

Molecular sieves인 AIPO₄-5, SAPO-5 그리고 SAPO-11을 수열합성하여 제조한 다음 XRD, SEM, NH₃TPD와 IR을 통해 물리화확적 특성을 조사하였다. 증기상에서 cyclohexanone oxime의 Beckmann 전이 반응 결과는 oxime의 전화율과 Lactam의 수율에 있어서 SAPO-11가 반응성이 우수하였고, WHSV의 변화에 있어서는 AIPO₄-5와 SAPO-5 경우 WHSV가 증가할수록 전화율과 선택도는 감소하였지만 SAPO-11는 선택도가 증가함을 보였다. 본 대상 반응계인 Beckmann 전이 반응에서는 촉매의 기공 크기보다는 산성도에 더 큰 영향을 받음을 알수 있었다. AIPO₄-5, SAPO-5 AND SAPO-11 which are molecular sieves were synthesized by hydrothermal crystallization. The crystallinity of the prepared catalysts was confirmed by XRD and SEM, and their acidic properties were examined by TPD of NH₃and IR. Catalytic characteristics of the catalysts were tested by vapor phase Beckmann rearrangement of cyclohexanone oxime to caprolactam. The conversion of lactam and yield of lactam increased with acidity of the catalyst. Among the tested catalysts, SAPO-11 was excellent in Beckmann rearrangement reaction. AIPO₄-5 and SAPO-5 showed that conversion of oxime and selectivity of lactam decreased with the increase of WHSV but SAPO-11 showed different tendency in selectivity of lactam, or selectivity of lactam increased with the increase of WHSV. Beckmann rearrangement reaction was affected by acidity than pore size.

Ginsenoside Rg3-enriched Korean Red Ginseng extract attenuates Non-Alcoholic Fatty Liver Disease by way of suppressed VCAM-1 expression in liver sinusoidal endothelium

Seoung-Woo Lee,Su-Min Baek,Young-Jin Lee,Tae-Un Kim,Jae-Hyuk Yim,Jun-Hyeok Son,Hee-Yeon Kim,Kyung-Ku Kang,Jong Hun Kim,Man Hee Rhee,Sang-Joon Park,Seong-Kyoon Choi,Jin-Kyu Park The Korean Society of Ginseng 2023 Journal of Ginseng Research Vol.47 No.3

Background: The incidence and clinical importance of nonalcoholic fatty liver disease (NAFLD) has emerged. However, effective therapeutic strategies for NAFLD have yet to be found. Panax ginseng (P. ginseng) is a traditional herb in Eastern Asia with therapeutic effects in many chronic disorders. However, the precise effects of ginseng extract on NAFLD are currently unknown. In present study, the therapeutic effects of Rg3-enriched red ginseng extract (Rg3-RGE) on the progression of NAFLD were explored. Methods: Twelve-week-old C57BL/6 male mice were fed a chow or western diet supplemented with high sugar water solution with or without Rg3-RGE. Histopathology, immunohistochemistry, immunofluorescence, serum biochemistry, western blot analysis, and quantitative RT-PCR were used for in vivo experiment. Conditionally immortalized human glomerular endothelial cell (CiGEnC) and primary liver sinusoidal endothelial cells (LSECs) were used for in vitro experiments. Results: Eight weeks of Rg3-RGE treatment significantly attenuated the inflammatory lesions of NAFLD. Furthermore, Rg3-RGE inhibited the inflammatory infiltrate in liver parenchyma and the expression of adhesive molecules to LSECs. Moreover, the Rg3-RGE exhibited similar patterns on the in vitro assays. Conclusion: The results demonstrate that Rg3-RGE treatment ameliorates NAFLD progression by inhibiting chemotaxis activities in LSECs.

Symmetry dictated grain boundary state in a two-dimensional topological insulator

Seoung-Hun Kang,Hyo Won Kim,Hyun-Jung Kim,Kisung Chae,Suyeon Cho,Wonhee Ko,Sangjun Jeon,Se Hwang Kang,HeejunYang,Sung Wng Kim,Young-Kyun Kwon,Young-Woo Son 한국진공학회 2020 한국진공학회 학술발표회초록집 Vol.2020 No.8