용해 현상에 대한 학생들의 개념유형 및 교사들의 지도 실태

강대훈,백성혜,박국태,Kang, Dae-Hun,Paik, Seoung-Hey,Park, Kuk-Tae 대한화학회 2004 대한화학회지 Vol.48 No.4

In this study, a survey was conducted of students of elementary through college on their conceptions of phenomenon related with dissolution, saturation, and extraction. The teaching strategies of elementary and secondary teachers related to dissolution phenomena were also investigated. Most of elementary and secondary school students thought of dissolution as a phenomenon in which particles broke into the spaces between other particles. This explanation called 'space conception' can be sought in elementary school science textbooks. Some of high school students also had this type of thought. A concept of dissolution phenomenon as 'hydration through attraction of solvent and solute' was held by most of students of 11th, 12th grade, and college. This explanation called 'attraction concept' can be sought in high school chemistry textbooks for 11th and 12th grade. But many students of elementary through college used analogies and models related to 'space conception' when they tried to explain the dissolution phenomena. This indicates that the 'attraction concept' was not firmly established in the students' cognition. 90% of elementary school teachers thought and taught dissolution as a phenomenon in which two different size particles were mixing together like as mixing beans and millets. The model does not represent the attractions among solvent-solvent particles, solvent-solute particles, and solute-solute particles. This model only represents the space size effect (smaller size particles fitting into the spaces of larger size particles). Half of the secondary school teachers also had 'space conception' and only 20% of the teachers had 'attraction concept' Many teachers who had 'attraction concept' used to represent explanation related to 'space conception' for teaching dissolution.

중학생들의 용해 현상 이해에 대한 연구

강대훈,백성혜,박국태,Kang, Dae Hun,Paik, Seoung Hey,Park, Kuk Tae 대한화학회 2001 대한화학회지 Vol.45 No.1

This study was to examine middle school students' understanding of dissolution. More than 75% students understood that dissolution was caused by small particles' filling the space between large particles due to the difference of size among particles. Some other students responded that solute disappeared or was absorbed in a solvent as the result of dissolution. Besides, they didn't know that space between particles was the reason of the volume's decreasing after the process of dissolution. Instead, they explained that space between particles caused dissolution. And they hardly understood the fact that solutes affect solubility. Students'misunderstanding about the concept of dissolution resulted from the lack of the explanation on the right concept of dissolution in science textbooks and the inappropriate use of the dissolution model by teachers. In conclusion, we need the appropriate explanation in middle school science textbooks that consider the students'level and the development of the appropriate model that demonstrates dissolution in the perspective of particles.

꾸지뽕열매 발효 추출물의 항산화 특성과 Elastase 및 Tyrosinase 저해활성

강대훈 ( Dae Hun Kang ),김재원 ( Jae Won Kim ),윤광섭 ( Kwang Sup Youn ) 한국식품저장유통학회(구 한국농산물저장유통학회) 2011 Food Science and Preservation Vol.18 No.2

We evaluated the nutritional value of 70% ethanol extracts (EE) from fermented cudrania tricuspidata fruit (ECT: EE of C. tricuspidata, EFCT: EE of fermented C. tricuspidata, EFCTL: EE of fermented C. tricuspidata by B. licheniformis, EFCTS: EE of fermented C. tricuspidata by B. subtilis) by determined the total polyphenol and flavonoid contents, antioxidant activities, and inhibitory actions on elastase and tyrosinase. The yields of freeze-dried powder of ECT, EFCT, EFCTL, and EFCTS were 54.22%, 54.43%, 57.51%, and 57.23% (each w/w), respectively. The color of L*, a*, b* values decreased of fermented cudrania tricuspidata. The fermented EFCTL and EFCTS had relatively higher contents of total polyphenol and flavonoid than those of other extracts. ABTS radical scavenging ability were 94.61%, 95.85%, 94.36%, and 96.69%, respectively. SOD (superoxide dismutase)-like activities were in the order EFCT (32.60%)>EFCTS (27.10%)>EFCT (23.30%)>ECT (22.00%), and nitrite scavenging activity was in order of EFCTS (51.18%)>EFCTL (45.61%)>EFCT (41.93%)>ECT (27.76%), respectively. Ferrous ion chelating activity of EFCTL (67.34%) and EFCTS (60.36%) was significantly the highest, whereas ECT (52.34%) and EFCT (51.73%) had not different significantly. Xanthine oxidase, elastase and tyrosinase inhibitory activities at 0.5% (w/v) solutions of EFCTL and EFCTS were somewhat higher than those of non-fermented ECT. In conclusion, we provide experimental evidence that extracts of fermented cudrania tricuspidata of B. subtilis and B. licheniformis exhibited higher antioxidant activities and inhibitory actions on elastase and tyrosinase compared with non fermented cudrania tricuspidata.

용해 현상에 대한 초등학교 과학 교과서의 내용 분석 및 지도 실태

강대훈 ( Kang Dae Hun ),백성혜 ( Baeg Seong Hye ) 한국초등과학교육학회 2003 초등과학교육 Vol.22 No.2

This study was to analyze how elementary school science textbooks explain dissolution and to examine the patterns of elementary school teachers` conceptions on dissolution and the teaching practices on dissolution of elementary school teachers. According to the result of the textbook analysis, the textbooks based on the 7th curriculum didn`t explain dissolution very differently from those based on the 6th curriculum. The contents dealing with dissolution in the textbooks of 7th curriculum became difficult gradually as the year went up, but the connected organization of the contents made students learn it easily. For example, in order to learn dissolution introduced first in the 3rd year 2nd semester textbook, students would tell soluble substance in water from insoluble substance in water as they put powdered substance in water. In the 5th year 1st semester textbook students were supposed to acquire the knowledge related to dissolution through the designed activities such as comparing solubility produced by different solvents and defining a solvent, a solute, dissolution, and a solution. In addition, teachers` guide for 5th year 1st semester textbook elucidated the principle of dissolution using attraction concept that was scientific. The result of the survey on teachers showed that 90% of elementary school teachers understood the dissolution of salt in water just as millet particles` filling the space between bean particles and they responded that they demonstrated millet particles` filling the space between been particles when they taught the dissolution of salt in water. When it comes to teachers who had the right idea on dissolution as the attraction conception, understanding was one thing and teaching was another, because they often instructed dissolution as the space conception in the real teaching.

중등학교에서의 용해 현상의 지도 실태 조사

강대훈(Dae Hun Kang),백성혜(Seoung Hey Paik),박국태(Kuk Tae Park) 한국교원대학교 과학교육연구소 2000 청람과학교육연구논총 Vol.10 No.1

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흡연 청소년의 흡연 빈도와 자살 시도에 영향을 미치는 요인

강대훈(Dae Hun Kang),김준원(Jun Won Kim),이종훈(Jong Hun Lee),윤서영(Seo Young Yoon),최태영(Tae Young Choi) 대한생물치료정신의학회 2018 생물치료정신의학 Vol.24 No.3

Objectives:Among adolescents, the proportion of daily smoking tends to increase with age, and does not return to the previous level. Therefore, we examined the factors associated with smoking frequency in a nationwide sample of Korean adolescents to help prevent the progression of smoking. Methods:Among 127,804 adolescents who participated in the 2016 and 2017 Korean Youth Risk Behavior Web-Based Survey, data from 7,781 adolescents who replied that they currently smoked were analyzed. According to the frequency of cigarette smoking, participants were classified into daily and non-daily smokers. Participants’ socio-demographic characteristics, smoking behavior, and psychological problems including perceived stress, depressive mood, and suicidality were assessed. Results:There were 3,627(47.4%) daily smokers and 4,154(52.6%) non-daily smokers. Low parental educational level, and early smoking experience were positively associated with daily smoking. High academic achievement, and high socio-economic status were negatively associated with daily smoking. Daily smoking was positively associated with lower happiness, lower sleep satisfaction, and severe stress during the past 12 months. Factors affecting suicide attempts of smokers were sex, residential type, socioeconomic status, and early smoking experience. Conclusion:The results indicated that socially disadvantaged families, and smoking experience with young age influenced daily smoking among Korean adolescents. Daily smoking was associated with psychological problems including lower happiness, lower sleep satisfaction, and severe stress. Early smoking experience influenced suicidal attempts among Korean adolescent smokers. Early intervention for smoking cessation in this high-risk group may contribute to prevention of these psychiatric complications of smoking.

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

백성혜,강대훈,김혜경,최우기,권균,Paik, Seoung Hye,Kang, Dae Hun,Kim, Hye Kyong,Chae, Woo Ki,Kwon, Kyoon 대한화학회 1999 대한화학회지 Vol.43 No.2

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.

초등학교와 중학교 과학 교과서의 화학 영역에 대한 연계성과 중학생들의 화학 개념에 대한 인식 분석

한유화,강대훈,양일호,백성혜,박국태,Han, Yu Hwa,Kang, Dae Hun,Yang, Il Ho,Paik, Seoung Hey,Park, Kuk Tae 대한화학회 1999 대한화학회지 Vol.43 No.3

This study was to analyze the articulation between chemistry contents of science textbooks at elementary and middle school level, to survey students ? perceptions on chemistry concepts, to establish guidelines for science textbooks that not only meet the needs of learners but also fit in a coherent way. In order to do this, we analyzed links of the aims and the organization of chemistry contents of elementary and middle school science textbooks, we also surveyed students' perceptions on chemistry concepts students had retained. The study revealed that the 6th middle school curriculum was almost a duplicate of the elementary school syllabus. And there was no interrelation between the organization of chemistry contents and the aim of the chapter which built up a logical picture of the world at a molecular level. It was also found that the lack of coherence between science textbooks in elementary and middle school was a major cause of student difficulty.

뇌컴퓨터접속(BCI) 무경험자에 대한 EEG-BCI 알고리즘 성능평가

김진권,강대훈,이영범,정희교,이인수,박해대,김은주,이명호,Kim, Jin-Kwon,Kang, Dae-Hun,Lee, Young-Bum,Jung, Hee-Gyo,Lee, In-Su,Park, Hae-Dae,Kim, Eun-Ju,Lee, Myoung-Ho 대한의용생체공학회 2009 의공학회지 Vol.30 No.5

The Performance research about EEG-BCI algorithm in BCI-naive subjects is very important for evaluating the applicability to the public. We analyzed the result of the performance evaluation experiment about the EEG-BCI algorithm in BCI-naive subjects on three different aspects. The EEG-BCI algorithm used in this paper is composed of the common spatial pattern(CSP) and the least square linear classifier. CSP is used for obtaining the characteristic of event related desynchronization, and the least square linear classifier classifies the motor imagery EEG data of the left hand or right hand. The performance evaluation experiments about EEG-BCI algorithm is conducted for 40 men and women whose age are 23.87${\pm}$2.47. The performance evaluation about EEG-BCI algorithm in BCI-naive subjects is analyzed in terms of the accuracy, the relation between the information transfer rate and the accuracy, and the performance changes when the different types of cue were used in the training session and testing session. On the result of experiment, BCI-naive group has about 20% subjects whose accuracy exceed 0.7. And this results of the accuracy were not effected significantly by the types of cue. The Information transfer rate is in the inverse proportion to the accuracy. And the accuracy shows the severe deterioration when the motor imagery is less then 2 seconds.

중학교 화학 분야의 개념 연구에 대한 문제점 분석

박은희,강대훈,백성혜,박국태,김혜경,채우기,권균,Park, Eun Hee,Kang, Dae Hun,Paik, Seoung Hey,Park, Kuk Tae,Kim, Hye Gyeng,Chae, Woo Ki,Kwon, Gyun 대한화학회 1999 대한화학회지 Vol.43 No.3

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 설문지A에서 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 학생들중에서 무개념으로 판단된 경우가 많았다.