• Journal of the Korean earth science society
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• v.26 no.8
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• pp.771-776
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• 2005

The purpose of this study is to survey the status of the 7th elective-centered curriculum and find problems in operating the system. 485 students in the tenth and eleventh grade were randomly selected as subjects. The results are as follows. (1) Among the students, 29% of them selected their science subject without considering their future jobs, 48% did it without enough overview of the system, and 25% did without clearly understanding the details the choice centered curriculum. (2) Among the students who participated in the survey, 65% of them showed positive responses concerning the needs of individual choice centered curriculum and 96% said it increased their participation in class. However, only 39% believed that operating this type of curriculum is realistically possible. (3) 89% of students selected their science subjects accordingly with the college preparatory courses and 14% selected based on their hopes. (4) The percentage of science subjects chosen are 40% for chemistry, 25% for biology, 22% for Physics, and 13% for earth science, but 74% of students wanted to change their choices. These results showed that students recognized the object of the 7th curriculum, but selected science subjects as a means of getting into college entrances, rather than carefully considering their future and aptitude.

• Journal of The Korean Association For Science Education
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• v.12 no.2
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• pp.109-128
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• 1992

Elementary science textbooks are the major instructional materials which contain sceientific objectives to be acquired by students. The purpose of this study is to analyze the development system, to evaluate the inquiry activity in current elementary science testbooks, and to make suggestions for the improvement of them. The questionnaires were administered to 116 subjects that participated in development of the 5th elementary science textbooks, and 86 of the subjects responded. Based on the data gathered and analyzed in this study, the major findings are as follows. First, regarding the analysis and evaluation of elementary science textbooks. 1. The instructional objectives in elementary science textbooks are analyzed. The proportions of comprehension objectives is 38%, scientific inquiry process objectives 21%, experimental skills objectives 7%, scientific attitudes and interests objectives 4%. 2. The science concepts in elementary science textbooks of the 3rd grade required the preconcrete operational level(82%) and of the 6rd grade required the postconcrete operational level (73%) by J. Piaget 3. The inquiry activities in elementary science textbooks are emphasizing gathering and organizing results and evaluation, and hypothesizing and designing an experiment Inquiry index of the elementary science textbooks is 76. This is significantly higher than 35${\sim}$50 of America and U.K.. 4. The number of questions per class hour is mostly three, and most of them require the students to explain phenomena in nature or in experiment Second, regarding the development system of elementary science textbooks. 1. The budget for and the period of the development of elementary science textbook should be expanded. 2. For the improvement of elementary science textbooks, more abundant resources and time should be used for the basic study and the field trial of textbooks. 3. The elementary science textbook must include the affective objectives as well as the scientific knowledges and scientific inquiry skills. 4. It is not desirable to assign equal number of pages to the content of physics, chemistry, biology, and earth science. 5. Closer cooperation system is needed among the ministry of education, development research center and the field trial schools.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.3
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• pp.362-370
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• 2002

During the last two decades, many new filling materials and material groups have been developed. the number of available restoratives has increased dramatically, especially during the last 5 years. Ormocers are a new class of materials which are still under development with regard to dental applications. However, in the chemical literature these materials have been known for a long time and used for producing scratch resistant coatings on plastic spectacle lenses. It is a combination of inorganic and organic materials. 'Ormocer' is an abbreviation for 'Organically Modified Ceramics'. These compounds are also known in the literature as 'Ormosils' (organically modified silicates). Their chemistry is comparable to that of silicones and organic polymers. The purpose of this study was to determine of compressive strength and flexural strength of a ormocer (Admira) and to investigate the effects of water absorption in comparison with three composite resins(Z-100, Tetric Ceram, Surefil) and one compomer(Dyract AP). The following results were obtained ; 1. Admira had the lower compressive strength than Surefil, but no statistically difference with other materials at 1 day(p>0.05). 2. Admira had the lower flexural strength than all other materials at 1 day. From 2 days, Admits showed lower flexural strength than three composite resin(p<0.05). 3. There was not statistically significant difference of compressive and flexural strengths between hybrid composite resin group(Z-100, Tetric Ceram) and Packable resin group(Surefil) for experimental period(30 days)(p>0.05). 4. All five materials showed an increase in compressive and flexural strength till 2 days and showed a decrease from 7 days in water(p<0.05). 5. Each materials had the statistically similar behavior of compressive and flexural strengths over time(p>0.05).

• Journal of the Korean Chemical Society
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• v.56 no.3
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• pp.371-377
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• 2012

In this study, open inquiry reports of 165 eighth graders in Daegu were analyzed in terms of content area, the types of inquiry hypothesis, and the types of inquiry variables. Before summer vacation, students learned about inquiry process and explored their own inquiry topic for two class hours. During summer vacation, students performed open inquiry including problem selection, designing and performing experiment, data collection, data analysis, and writing report. After the vacation, students submitted their reports, and answered to additional survey regarding the source of inquiry idea, the definition of hypothesis, and the most difficult step of inquiry process. As a result, chemistry was the most dominant content area of the reports and biology and life science were the next. 130 out of 165 reports included inquiry hypotheses, and most of them were predictive hypotheses. In many reports, dependent and independent variables could not be identified because of their ambiguity. However, inquiry variables described in experimental design, which were mostly categorical variables, were clearer than those described in inquiry subject and inquiry hypothesis. The most difficult step of inquiry process for students was to generate an idea for open inquiry.

• Analytical Science and Technology
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• v.17 no.1
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• pp.69-81
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• 2004

The formation pattern of DBPs (disinfection by-products) in raw water treated with hypochlorite, chlorine disinfectant was studied. TOC (total organic carbon), residual chlorine, turbidity and 14 DBPs in raw water from Han-river and Nakdong river during 1 ~ 14 days were determined. Total DBPs in Han river was 101.3 ng/mL (789.6 nM) after 7days and THMs (trihalomethanes) are the dominant portion of 68%. HAAs (haloacetic acids) and chloral hydrate were determined 19% and 10% respectively. In Nakdong river total DBPs was 98.4 ng/mL (678.6 nM) and dominant class was HAAs. (55.8 ng/mL, 57%) THMs(34%) and N-compounds like HANs (haloacetonitriles, 5%) and chloropicrin were increased. It may be explained that high concentration of NH4-N in Nakdong river react with chlorine produced chloramine and this formed different pattern of DBPs. As a result, total DBPs formation pattern depends on raw water and disinfectant and in generally the initial concentration of acidic HAAs was high and THMs was increased gradually.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.1
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• pp.55-63
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• 2001

N fertilizer recommendations to optimize with consideration to maximum crop yields, maximum profits, and minimum N losses to ground or runoff water, an advisory system. Nitrogen Expert System (NES), was developed. The system was to estimate the optimal rate of N fertilizer application cornfields in Illinois. NES was constructed using Smart Elements, a knowledge-based system that manages the expertise of human experts. NES was reinforced by addition of the effect of a productivity index (PI), soil organic matter content (SOM), and pre-sidedressing of nitrate concentration (PSNT) to the optimal N fertilizer recommendation. NES contains 49 rules, 1 class, 14 objects, and 2 properties. NES was successfully operated, showing N recommendations with inputs of three soil properties including PI, SOM, and PSNT. NES can reduce N loss to the environment, but adherence to the recommendations may also reduce farmers income. Therefore, NES will be more effective by evaluating both environmental damage assessment and other economic agricultural management parameters and other soil physico-chemical parameters.

• Korean Journal of Ecology and Environment
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• v.56 no.3
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• pp.229-241
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• 2023

Microphysogobio rapidus is designated as endangered species class I by Ministry of Environment, and its distribution and population have been gradually declining, and it is now limited to the Nam River and some tributary streams of the Nakdong River Watershed. For the restoration of this highly endangered species, it is important to identify the causes of the decline and establish appropriate restoration plans. However, due to lack of basic data and ecological research, most steps are stagnant. Therefore, in this study, we identified the differences in the physical, biological, and sociological habitats between current and past distributed sites through field surveys and literature reviews. As a result of the field survey, there were differences in conductivity between the current and past distributed sites, and fish communities were also showed differences. The literature data also showed that the physico-chemical values of the past distributed sites were generally unfavorable, which generated negative consequences on biological factors. In particular, the effects of urbanization were found to be a major factor affecting the habitat of M. rapidus. Habitat stabilization is crucial for the recovery of this endangered species. However, in the past distributed sites, disturbances such as stream development and weir construction have altered streams physico-chemically and result in changes of M. rapidus. Therefore, a comprehensive plan that considers both stream connectivity and water quality is needed to manage and restore the habitat of M. rapidus.

• Journal of The Korean Association For Science Education
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• v.26 no.3
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• pp.376-384
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• 2006

The purposes of this study were to analyze the frequency and type of volition strategy, according to achievement level, employed by students with high learning motivation, and to identify the role volition strategy plays in keeping students motived to learn science. To accomplish these aims, two groups of students(each containing three members) were selected. Students in the two groups both had the same cognitive level and high learning motivation. However, one group's science achievement was high, and the other was low. Through interviews and class observations, volition strategies students in the two groups used when they encountered hindrances in science learning were compared. Results of the study revealed a relationship between achievement level and volition strategy. Students showed differences in the frequency and types of volition strategies used according to science achievement. It was found that students with higher achievement levels used volition strategies more often to overcome hindrances in science learning than those with lower achievement levels. Furthermore, students with higher achievement levels generally used internal mind control strategies while those with lower achievement levels used environmental control strategies. Lastly, findings found that the types of volition strategies used by lower achievement level students were very limited.

• Journal of The Korean Association For Science Education
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• v.27 no.7
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• pp.631-638
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• 2007

This study investigated the influences of a student-centered analogical instruction using physical analogies upon students' conception and application, retention of conception and application, perceptions of science classroom environment, and perceptions of analogical instruction. Six classes of seventh graders (N=208) at a middle school in Seoul were assigned to the control, the teacher-centered analogy (TCA), and the student-centered analogy (SCA) groups. They were taught about 'three states of matter' and 'motion of molecules' for 8 class hours. Analysis of the results revealed that the scores of the SCA group were significantly higher than those of the other groups in the conception test, retention test of conception and application, and perception test of science classroom environment. The scores of the SCA group in the application test were also higher than those of the other groups, but there was a significant difference only between the control and the SCA groups. The TCA group performed significantly better than the control group only in the test of the retention of application. In addition, the students in the SCA group exhibited more positive perceptions of the analogical instruction than those in the TCA group. Educational implications are discussed.

• Journal of The Korean Association For Science Education
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• v.29 no.6
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• pp.741-750
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• 2009

Modem science education was introduced to Korea in the enlightenment period. The science textbooks which were published at that time were important to modem science education in Korea. Therefore, the translators and publishers of science textbooks were the leader of the science education in the enlightenment period. Hyun Chae and his son as a translator were one of the leaders in science education at that time. Hyun Chae was born to a Middle class (中人)family and succeeded to pass the national examination for translators (譯科). He worked as a translator and author at the Ministry of Education (學部). Also, he was the associate teacher in a foreign school and the Hansung normal school (漢城師範學校). He published 26 books. One of them, Rikwa (理科) as the science textbook covering all the areas of science, physics, chemistry, biology and earth science. That presented the knowledge, which students should know by proper method, induced students' interest and included various experiments. Hyun Chae's activity in science education as the author and translator of science textbooks was an important role on the forming science education in the enlightenment period because it was caught short of science textbooks. The author, translator, and publisher of science textbooks was of great significance to make science popular, which was the new culture. Therefore, the role and activities in science education of Hyun Chae was a part of the history of science education, he knew a foreign language and was the leader in facilitating exchange with foreign countries.