• Journal of the Korean Chemical Society
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• v.62 no.3
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• pp.214-225
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• 2018

In this study, we tried to find out how heat and thermal energy terms are defined and used in Korean science textbooks, and to see if there are any differences in the meaning of these terms used in different areas of science. For this purpose, the contents of 52 science textbooks of elementary, middle and high school published by the 2009 revised curriculum were analyzed. The definition of the term heat is given in the middle school Science(1) and the high school Physics I and II textbooks. Most textbooks define heat as "energy transferred due to a temperature difference (Type I)". Only one textbook of Physics I defines heat as "transfer of energy due to a temperature difference (Type II)". The definition of thermal energy is mostly presented in the middle school Science (2) and the high school Physics I textbooks. Physics I textbooks define the thermal energy as "molecular kinetic energy (Type III)", while Science(2) textbooks define it as Type I or "energy causes temperature change or phase transition of matter (Type IV)". In the texts of textbooks, heat is mainly used as the meaning of Type I or Type III. Thermal energy is mainly used as Type III, but it is also used as Type I in the high school Physics and Chemistry textbooks. The meanings of heat and thermal energy terms used are differed by the area of science. They are mainly used as type I or type III in Physics and Chemistry textbooks, and used as type III in Life Science and Earth Science textbooks.

• Journal of the Korean Chemical Society
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• v.54 no.4
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• pp.465-470
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• 2010

Using interesting video clips corresponding to lesson subjects for students who favour visual representation is one of the good methods to enhance students' preference for science class. There are many moving picture web sites to get video clips easily via internet and 'YouTube' is very popular and one of the largest reservoir. In this study, every student in the 'Chemistry I' class, which is a class for 11th grade, was requested to search a video clip corresponding to lesson subjects and to make a presentation in the class. After 1st semester, students' response about the class using YouTube was examined by survey. As a result, students preferred and were interested in the class using YouTube than class centered on textbook. And students preferred YouTube clips showing unusual experiments that were related with contents of subject. In addition, experiments and watching their real phenomena were an interesting factor and helpful factor of learning chemistry in YouTube video clips, respectively. However, translation of English used in the video clips seemed to be a difficult part for students.

• Journal of Life Science
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• v.9 no.2
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• pp.207-211
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• 1999

Biologically active compounds in Polygonatum sibiricum were extracted using organic solvents as hexane, CHCl$_3$, n-butanol corresponding each component. Compound I was purified from hexane layer and the chemical structure of compound I was characterized using 1H-NMR, 13C-NMR, DEPT135, COSY, HMQC, HMBC spectrum and MS-spectrum. Consequently, the chemical structure of compound I was determined as 9,12-(9E,l2E)-octade cadienoic acid.

• Journal of the Korean Chemical Society
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• v.36 no.1
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• pp.107-112
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• 1992

Electron injection from excited rose bengal into the conduction band of a thin film of $SnO_2$ semiconductor in acetonitrile was investigated in an electrochemical cell, ITO/$SnO_2$/rose bengal, NaI or $I_2$, $NaClO_4$/Pt. It was observed that NaI enhanced the supersensitized photocurrent, followed by the slow reduction, whereas $I_2$ yielded a fast decaying photocurrent. Spectroscopic analyses of the dye solution containing NaI revealed that electron is transferred to the $SnO_2$ electrode from the reduced rose bengal and iodide is responsible for the reduction of the dye in triplet state. However $I_2$ appears to possess neither the reducing ability of the oxidized dye nor the retardation of the dehalogenation of RB.

• Journal of the Korean Chemical Society
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• v.56 no.1
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• pp.137-143
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• 2012

This study analyzed the questions posted on the chemistry Q&A board by students and teachers in a chemistry education homepage, in order to understand the difficulties in learning and teaching chemistry. The different tendencies were found in the contents and the motivations of questions by students and teachers. In Chemistry I, students raised many questions in the 'Water' unit, while teachers raised many ones in the 'Chemical compound in our life' unit. In Chemistry II, students asked many questions in the 'Gas, liquid, solid' unit, while teachers did in 'Chemical reaction and energy' unit. Students' motivations of questioning were 'Explanation of unclear concept', and 'Problem solving', while teachers' motivations were 'Searching information', and 'Question in experiment'. The Q&A board provided a field in exchanging informations needed in learning and teaching chemistry. Educational implications were discussed on the use of Q&A board in chemistry education.

• Journal of the Korean Chemical Society
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• v.51 no.6
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• pp.560-568
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• 2007

The aim of this study is to investigate the terminology of chemically unclear ‘heavy metals' which were expressed in the Korean secondary science textbook in terms of the definition, the type and the meaning. Initial results showed that six of ‘Chemistry I' textbooks among these texts defined a heavy metal with the density and described it as a metal which is hazardous and continuously accumulated in the human body. Specifically, cadmium, lead and mercury were presented as examples of the hazardous metal in all of the eight textbooks but non-metals such as arsenic and absolutely essential metals including chrome, manganese, iron, cobalt, nickel and copper were also given in the texts. Most of the texts described the hazardousness and toxicity of the metal too simple to understand the mechanism of its intoxication despite considering all of the factors including its oxidation state, residual amount and reactivity with biomolecules of the human body. Such an ambiguous definition and explanation may excluded in the textbook because the chemically undefined chemical vocabulary leads students to cause an alternative conception of the heavy metal, which means that the metal could be identical with toxins.

• Journal of the Korean Chemical Society
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• v.14 no.3
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• pp.277-279
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• 1970

• Journal of the Korean Chemical Society
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• v.6 no.1
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• pp.61-63
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• 1962

The polarographic behaviors of Tl(I) was investigated in EDTA and NTA as supporting electrolytes for determination of Tl(I). A base solution containing 0.005 % gelatine, 0.1 M EDTA, and 0.05 M NTA was used. The halfwave potential of Tl(I) determined is -0.495 V v.s. S.C.E. in 0.1 M EDTA at pH 4.1 and -0.520V v.s. S.C.E. in 0.05 M NTA at pH 6.3. In this paper, the effects of gelatine concentration and pH values was investigated. The half-wave potentials of common elements was determined and compared with the half-wave potential of Tl(I).

• Journal of the Korean Chemical Society
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• v.55 no.6
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• pp.994-999
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• 2011

Some novel heterocyclic derivatives of 1,1-bis(2-phenyl-5-arylidine-1,3-thiadiazolidin-4-one)cyclopropane 4(a-i) have been synthesized from cyclopropane dicarboxylic acid and substituted thiadiazole moieties. All the synthesized compounds have been characterized by elemental and spectral (I.R., $^1H$-NMR, Mass) analysis. Furthermore, above said compounds were screened for their antifungal and antibacterial activities. Compound 4c was found the most potent one which further evaluated for lesser toxicity test.

• Journal of the Korean Chemical Society
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• v.54 no.4
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• pp.471-478
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• 2010

This study analyzed the vocabulary level in the 'Water' unit of chemistry I textbook. It also analyzed its relevance to the 11th graders' vocabulary level. The main tool for analyzing vocabulary level was SWA(Science Word Analysis) program which was referenced the Standard Korean Dictionary and Graduated Vocabulary of Korean Language Education. The results in this study turned out to be as follows: The distribution of scientific vocabulary level increased from Level-1 to Level-3 and showed a tendency to decrease from Level-3 until Level-5. The average percentage of Out of level is the largest as 37%. The highest percentage of non-scientific vocabulary was Level-1. The distribution of non-scientific vocabulary level decreased progressively. The Level-5 and Out of level are used 18% averagely. So, there are 6 vocabularies of Level-5 and 82 vocabularies of extra-level inappropriate in scientific vocabularies. And there are 53 vocabularies of Level-5 and 145 vocabularies of Out of level inappropriate in non-scientific vocabularies. Therefore, the overall state of textbooks for grade 11 students are reasonable. But there are a great many vocabularies inappropriate for them. Those should be used minimum, and to be changed to the 1-4 of level vocabulary as stated in the student's level of understanding of appropriate vocabulary.