• The Mathematical Education
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• v.48 no.1
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• pp.81-91
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• 2009

This paper focuses on two problems in the 10th grade mathematics, the rational zero theorem and the content(the integer divisor) of a polynomial Among 138 students participated in the problem solving, 58 of them (42 %) has used the rational zero theorem for the factorization of polynomials. However, 30 of 58 students (52 %) consider the rational zero theorem is a mathematical fake(false statement) and they only use it to get a correct answer. There are three different types in the textbooks in dealing with the content of a polynomial with integer coefficients. Computing the greatest common divisor of polynomials, some textbooks consider the content of polynomials, some do not and others suggest both methods. This also makes students confused. We suggests that a separate section of the rational zero theorem must be included in the text. As for the content of a polynomial, we consider the polynomials are contained in the polynomial ring over the rational numbers. So computing the gcd of polynomials, guide the students to give a monic(or primitive) polynomial as ail answer.

• Journal of Ginseng Research
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• v.40 no.2
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• pp.121-126
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• 2016

Background: Ginsenoside F1, a pharmaceutical component of ginseng, is known to have antiaging, antioxidant, anticancer, and keratinocyte protective effects. However, the usage of ginsenoside F1 is restricted owing to the small amount found in Korean ginseng. Methods: To enhance the production of ginsenoside F1 as a 10 g unit with high specificity, yield, and purity, an enzymatic bioconversion method was developed to adopt the commercial enzyme Cellulase KN from Aspergillus niger with food grade, which has ginsenoside-transforming ability. The proposed optimum reaction conditions of Cellulase KN were pH 5.0 and $50^{\circ}C$. Results: Cellulase KN could effectively transform the ginsenosides Re and Rg1 into F1. A scaled-up biotransformation reaction was performed in a 10 L jar fermenter at pH 5.0 and $50^{\circ}C$ for 48 h with protopanaxatriol-type ginsenoside mixture (at a concentration of 10 mg/mL) from ginseng roots. Finally, 13.0 g of F1 was produced from 50 g of protopanaxatriol-type ginsenoside mixture with $91.5{\pm}1.1%$ chromatographic purity. Conclusion: The results suggest that this enzymatic method could be exploited usefully for the preparation of ginsenoside F1 to be used in cosmetic, functional food, and pharmaceutical industries.

• Journal of Environmental Health Sciences
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• v.28 no.2
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• pp.99-108
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• 2002

This study was carried out to evaluate the Physicochemical characteristics of mined waste(separated waste and soil) and to predict environmental effect of an old landfill site located at north of Seoul. Municipal solid waster(MSW) had been disposed of at the old landfill site used in this study for about 2 years(1990-1992). The old landfill site selected for this study had accepted mainly municipal solid waste. The landfill-mined waste contained separated waste (40.9%) and soil(59.1%) by wet weight basis. The separated waste consisted of combustible(91.0%) and non-combustible(9.0%). The combustible waste was mainly non-biodegradable plastics. The low heating value of the separated combustible waste, which is calculated by Dulong's equation, was as high as 3,470kcal/kg. According to the Korean Extraction Procedure, separated waste and soil were proved to be not hazardous. The total content of heavy metal in the separated waste and soil met standard of California State, USA. Therefore the separated waste may be relandfilled at a sanitary landfill site and/or burned up at an incinerator, and the separated old soil may be used ad landfill cover-soil at a sanitary landfill site. Water quality of two streams was grade IV, of which water could be used as industrial and agricultural water. The streams near the landfill site might not be contaminated by leachate from the old landfill site. It was estimated that organic matter in the old landfill site would not be actively biodegraded within a short period of time.

• Journal of Korean Elementary Science Education
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• v.30 no.2
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• pp.232-241
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• 2011

The purpose of this study was to compare socio-linguistic characteristics and instructional influences of two different types of texts, which were narrative and expository. Socio-linguistic characteristics of two different types of texts were analyzed in their content specialization, linguistic formality, and social-pedagogic relationships. Expository texts showed strong scientific classification, and medium level of linguistic formality, and low level of social-pedagogic relationships. Narrative texts showed different characteristics. The instructional effects were investigated with 91 fifth grade elementary students in three classes. Each class was randomly assigned into three groups: expository text group, narrative text group, control group. The results showed that the science achievement scores of the narrative text group was higher than those of other groups. The affective domain test scores of the expository text group were higher than other groups. The perception of students on informational science text were generally positive both types of texts.

• Korean Institute of Interior Design Journal
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• no.22
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• pp.85-91
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• 2000

The purpose of this study is to grasp the element and method of traditional expression appeared in hotel lobby spaces, and present the direction of traditional expression applicable to the domestic hotel lobby space. Therefore, this study analyzed traditional expression according to its element and method taken out from the prior researches related to it. Specifically, the element of traditional expressions divided into the element of space organization, the element of structure (bottom, wall, ceiling, window, door and pillar), and the element of decorative design(furniture, illumination, artistic ornament, color, and material). The method of traditional expressions divided into the method of prototype reappearance, prototype transformation, reinterpretation, and abstract. The target of analysis has been 27 hotels designed since 1970s. and described as expressed traditionality in architecture-technical journals and books in the inside and outside of the country. considering these results, it seems that the traditional expressions using more various elements and more various element and methods have to used in domestic hotels. Specifically, when expressing traditionality in the lobby space of domestic hotel, it is important to decided the method expressing traditionality at first, and the traditional expressions using the element of space organization, structure, decorative design, and so based on the method expression traditionality was fulfilled with coordination.

• Journal of the Korean Home Economics Association
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• v.43 no.7 s.209
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• pp.79-91
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• 2005

The purpose of the study was to examine the current status of financial management behaviors of college students and to determine the affecting factors. The data were collected from 481 college students in Busan and Kyungnam areas by a self-administered questionnaire. Frequencies, Cronbach's alpha, factor analysis Pearson's correlation analysis and regression analyses were conducted by SPSS WINDOWS. The results from this study were as follows. first, the mean of preparation for the future was the highest among 5 dimensions of money attitudes, whereas the mean of the ostentatious means was the lowest. In addition, the college students showed good practices in drawing up shopping lists, budgeting, and keeping receipts, but bad practices in short-term and long-term planning. Second, many factors such as gender, grade, mother's education, fathers' occupation, and mothers' occupation were significant in the regression analyses for the financial management behaviors. Especially, money attitudes and experience of consumer education were significant in many categories of financial management behaviors. In combination, these results suggest that financial management education for college students should be conducted, and that contents related to value should be included in the education program.

• Journal of the Korean Home Economics Association
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• v.37 no.1
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• pp.91-108
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• 1999

The purpose of this study was to investigate the correlation between children's perceptions of interpersonal relations (parents, family, and peers) and those of self, and to examine how the perceptions are related ot problem-solving and social preference. The subjects of this study were 625 children of 5th and 6th grade in 4 primary schools in Taejon City. Results showed positive correlations among four measures of social perceptions (to parents, to family, to peer, and to self). Therefore we have found generalization among children's representations across four interpersonal domains-that is, parents, family, self, and peer. Children's problem solving-behaviors were most significantly related with parents/family domains among interpersonal relationships. In the case of boys, direct path between the perceptions of parents/family and problem solving-behavior was significant, whereas girls' perception of parent/family was associated with problem solving-behavior both directly and indirectly, through girls' perceptions of self and peer. Social preference was highly correlated with perceptions of peer and of father. This study has found that both boys' and girls' peer representations were established for the role as mediators between parents/family representations and peer ratings of social preference. These findings revealed that the impact of family representations on peer rejection was mediated by children's beliefs about their peers.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.4
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• pp.91-96
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• 2018

This study is collects design data through the process design of the organic Rankine cycle, which can produce 20kW of electric power through the recovery of waste heat. In this study, the simulation was conducted by using APSEN HYSYS in order to make the model for the process design of the 20kW class waste heat recovery system. For the thermodynamic model, the test was conducted with hot water as the heat source, with the water steam used as the cooling water for the cooler and the refrigerant R245fa in the cycle. In Case 1 and Case 2, it was expected and found that the cycle efficiency was 10.6% and that 36.86kw was produced, considering the margin of 84% of 20kW. In Case 3 and Case 4, it was expected and found from the simulation that the cycle efficiency was 12% and that 30.0kw was produced, considering the margin of 84% of 20kW.

• School Mathematics
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• v.11 no.1
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• pp.71-91
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• 2009

The purpose of this study was to analyze operation sense in detail with regard to division of fraction. For this purpose, two sixth grade students who were good at calculation were clinically interviewed three times. The analysis was focused on (a) how the students would understand the multiple meanings and models of division of fraction, (b) how they would recognize the meaning of algorithm related to division of fraction, and (c) how they would employ the meanings and properties of operation in order to translate them into different modes of representation as well as to develop their own strategies. This paper includes several episodes which reveal students' qualitative difference in terms of various dimensions of operation sense. The need to develop operation sense is suggested specifically for upper grades of elementary school.

• Journal of the Korean Home Economics Association
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• v.43 no.3 s.205
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• pp.91-104
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• 2005

This study was designed to examine the relations of home environment, locus of control, social support and behavior problems of fourth-grade Korean-Chinese children in Yanbian in China. The subjects were 190 children who completed the locus of control and social support scale and their parents who completed the Child Behavior Checklist. T-test, correlation analysis, and multiple regression analyses were conducted. Mother's education level, and psychological and physical environment at home were negatively related to children's behavior problems. The scores of internal locus of control and support from the teacher were negatively related to children's behavioral disturbances. The factors with the greatest contribution to explaining behavior problems of Korean-Chinese children in Yanbian were found to be physical environment at home, internal locus of control, and teacher's social support.