• Journal of Science Education
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• v.34 no.2
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• pp.342-358
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• 2010

By using the concept of 'Resonance' in benzene which stems from a unit dealing with the carbocyclic compounds which is in a text 'Chemistry I', I developed teaching methods based on the history of science. This study was executed to analyze the effect by applying these methods. Seventy 3rd grade male students, who are attending a high school located in the Pohang area were used in this study. I investigated the level of the relative difficulty and the degree of scholastic achievement from each treatment group and controlled group using the concept of Resonance from the preceeding study. In this study, these 70 students divided into two classes- a traditional lecture group consisting of male 35 student, and a group using the history of chemistry consisting of the remaining 35 student and after a specified period, their scholastic achievement was analyzed. As a result of this study, the treatment group scored much higher (50.143) than the controlled group(25.429) in average score and showed significant difference between two groups. Through this study was based on the history of chemistry, after scientists let them realize the process of improving science attitude, and think like scientists, giving conceptual class can get much more efficiency and durability for learning.

• Journal of the Korean Chemical Society
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• v.53 no.6
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• pp.793-804
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• 2009

In this study, high school students' perceptions of chemically ill-defined ‘heavy metals’ were examined through questionnaires. Nineteen classes of 11th graders (N = 611) were divided into two groups according to completion of 'Chemistry I', which were 10 science-classes and 9 liberal art-classes and compared each other. Three terms of students' cognition and definition, impact on the formation of their cognition, and their chemical knowledge of 'heavy metals' were analyzed by SPSS. The findings revealed that most of students recognized ‘the heavy metal’ as the metal which causes to be accumulated on any living thing and is hazardous in human body regardless of different major between liberal art and science. Mass media and school instruction were found to be the greatest impact on the formation of these cognitions. Especially, school instruction had more effects on students majoring in science than students majoring in liberal art, which bring the result that students in science-classes have more misconception about the definition of 'heavy metals' with human toxicant regardless of metal species and its content in human body and physical density due to the ill-defined terminology of the textbook than students in liberal art-classes do. It is interesting that students in science-classes understood hazard and chemical structure of 'heavy metals' better, while students in liberal art-classes answered the question better about hazardous properties of heavy metals.

• Journal of the Korean Chemical Society
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• v.11 no.3
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• pp.94-99
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• 1967

The interactions of iodobenzene with iodine, iodine monobromide, iodine monochloride and chlorine in carbon tetrachloride solution have been investigated by means of ultraviolet spectrophotometric measurements. The results reveal the formation of one to one molecular complexes, $C_6H_5I{\cdot}I_2$, $C_6H_5I{\cdot}IBr$, $C_6H_5I{\cdot}ICl$, and $C_6H_5I{\cdot}Cl_2$, in solution. The equilibrium constants obtained at room temperature (about $21^{\circ}C$) for the formation of these four complexes are 0.23, 0.73, 1.2 and 0.070 l $mole^{-1}$, respectively. Comparison of these results with those reported in the literature on other complexes of similar type indicates that the relative stabilities of these complexes decrease in the following orders: ICl>IBr>$I_2$>$Br_2$>$Cl_2$ $C_6H_5I$>$C_6H_6$>$C_6H_5Br$>$C_6H_5Cl$>$C_6H_5F$.

• Journal of the Korean Chemical Society
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• v.48 no.5
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• pp.519-526
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• 2004

The purpose of this study was to search pre-service teachers?and chemistry teachers?conceptions related to electrolysis process by predicting electrolysis products in NaI solution. A questionnaire developed by the researchers and following interviews were adopted for the research. By the methods, the conceptions of the groups were compared. Also, the relationship between their conceptions and explanations of chemistry II textbooks and general chemistry books was examined. From the analysis, it was found that most of the pre-service teachers had difficulties in using standard electrode potential when they predicted products of electrolysis. Most of the chemistry teachers could use standard electrode potential, but it was difficult to understand water electrolysis in redox reaction. The explanations of chemistry II textbooks also contained misconceptions.

• Journal of the Korean Chemical Society
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• v.64 no.3
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• pp.189-195
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• 2020

In the study, the effect of flipped classroom approach applied to chemistry I class in a foreign language high school was explored. Flipped classroom was applied to 176 grade 10 students (43 boys and 133 girls) from a foreign language high school located in a metropolitan city for one semester and its instructional effects were studied in terms of cognitive and affective aspects. Before the class, students were provided with guiding worksheets and asked to summarize contents. Within the class, various student-centered activities were adopted. After the flipped classroom for one semester, mid-term and final-term exam scores were analyzed, and students' attitude toward chemistry class and flipped classroom were surveyed. Analysis on the exam scores showed the possibility for positive impact on students' achievement and perceptions on chemistry class including flipped classroom approach. Moreover, some students mentioned flipped classroom was helpful for self-directed learning and meta-cognition. Based on these results, educational implications were discussed.

• Journal of the Korean Ceramic Society
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• v.19 no.3
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• pp.199-204
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• 1982

Bowl 형태의 일본산 Nagano 점토에 대한 분류 및 특성화 연구를 하였다. 결정입자 크기를 1$\mu$ 이하로 침강분리 시킨후 전자현미경으로 결정형태를 관찰하였다. 아울러 결정형태, 구조적 결함 및 intercalation 반응성의 상호관계를 검토하기 위하여 tube 형태의 한국산 halloysite 및 plate 형태의 kaolinite를 비교 조사하였다. 특이한 Bowl 형 Nagano 점토는 tube형 halloysite와 화학 반응성에서 동일하여 극성 내지는 hydrogen bridge 결합을 하는 guest 분자와 반응하여 층간삽입 화합물을 형성 하였다. 화학반응성에 따른 점토분류방법에 의해 Nagano 점토가 halloysite임을 밝혔으며 아울러 결정의 형태는 반응성에 영향을 미치지 않음을 알 수 있었다.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.23-26
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• 2010

A Schiff base ligand (Z)-N-((Z)-2-(sec-butylimino)-1,2-diphenylethylidene)butan-2-amine was synthesized by condensation of benzil with sec-butyl amine. Complexation of the ligand was carried out with first row transition elements, manganese(II) and nickel(II). Ligand and complexes were characterized by FTIR, elemental analysis and thermogravimetric analysis in solid state and by NMR ($^1H,\;^{13}C$) in solution form. Both the complexes demonstrate good catalytic activity for butadiene oligomerization under mild conditions with methylaluminoxane (MAO) as co-catalyst.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.5 s.248
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• pp.397-404
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• 2006

Effects of surface defect distribution on flame instability during flame-surface interaction are experimentally investigated. To examine chemical quenching phenomenon which is caused by radical adsorption and recombination processes on the surface, thermally grown silicon oxide plates with well-defined defect density were prepared. ion implantation technique was used to control the number of defects, i.e. oxygen vacancies. In an attempt to preferentially remove oxygen atoms from silicon dioxide surface, argon ions with low energy level from 3keV to 5keV were irradiated at the incident angle of $60^{\circ}$. Compositional and structural modification of $SiO_2$ induced by low-energy $Ar^+$ ion irradiation has been characterized by Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). It has been found that as the ion energy is increased, the number of structural defect is also increased and non-stoichiometric condition of $SiO_x({\le}2)$ is enhanced.

• Bulletin of the Korean Chemical Society
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• v.28 no.3
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• pp.474-476
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• 2007

• Journal of the Korean Chemical Society
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• v.28 no.6
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• pp.349-354
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• 1984

The relative viscosities and the osmotic coefficients of alkaline metal iodides (NaI, KI, RbI, CsI) in methanol, ethanol, dimethylsulfoxide (DMSO), and sulfolane (TMS) have been measured by Ubbelohde viscometer and vapor pressure osmometry at 45 ∼ $120^{\circ}C.$ The order of A and B coefficients in viscosity for alkaline metal iodides are MeOH > EtOH > TMS > DMSO, and TMS > EtOH > DMSO > MeOH. dB/dT values for the alkaline metal iodides are in the order of NaI > KI > RbI > CsI in the protic solvents, while those for the aprotic solvents are in the reverse order. The order of the osmotic coefficients for the alkaline metal iodides is EtOH > DMSO > MeOH > TMS.