• Journal of the Korean Wood Science and Technology
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• v.46 no.1
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• pp.73-84
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• 2018

Recently, the importance of flame retardation treatment technology has been emphasized due to the increase in urban fire accidents and fire damage incidents caused by building exterior materials. Particularly, in the utilization of wood-based building materials, the flame retarding treatment technology is more importantly evaluated. An Intumescent system is one of the non-halogen flame retardant treatment technologies and is a system that realizes flame retardancy through foaming and carbonization layer formation. To apply the Intumescent system, composite material was prepared by using Ethylene vinyl acetate (EVA) as a matrix. To enhance the flame retardant properties of the Intumescent system, a nano-clay was applied together. Composite materials with Intumescent system and nano - clay technology were processed into sheet - like test specimens, and then a new structure of cross laminated timber with improved flame retardant properties was fabricated. In the evaluation of combustion characteristics of composite materials using Intumescent system, it was confirmed that the maximum heat emission was reduced efficiently. Depending on the structure attached to the surface, the CLT had two stages of combustion. Also, it was confirmed that the maximum calorific value decreased significantly during the deep burning process. These characteristics are expected to have a delayed combustion diffusion effect in the combustion process of CLT. In order to improve the performance, the flame retardation treatment technique for the surface veneer and the optimization technique of the application of the composite material are required. It is expected that it will be possible to develop a CLT structure with improved fire characteristics.

• Journal of Korean Society of Transportation
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• v.23 no.5 s.83
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• pp.47-55
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• 2005

Roads deeply affect the life of people and keep doing an important role to support economic growth of a country. According to the budget plan of the ministry of construction and transportation of Korea, 8.1 trillion won have been allotted for road investment in the year of 2002 which occupy 61% of the transportation infrastructure special account (13.3 trillion won) and 4.7% of the total national budget (1,740 trillion won). It is true that services generated from road investment such as mobility enhancement and increased accessibility have shown positive effects through shortened travel time and decreased vehicle operating cost. However, it is also notable that many negative effects are gradually being discussed and those are nowadays getting severer due to enhanced people interests about road construction, increased concerns on environment and active public involvement that were evoked by traffic accidents, air pollution & noise and destruction of environment. Road construction processes in Korea are normally governed by administrative sectors (suppliers) not by users. These processes ate very weak to accomodate user s needs and community concerns thus easy to fail finalizing a road project without hassles. A public hearing process is supposed to be held in the processes of detailed design step and the environmental impact analysis. However, it is not enough to grab user's needs and community concerns. Increased public involvement frequencies, optimized public involvement timing and enhanced depth of public involvement magnitude are suggested to improve the current poor public involvement schemes in road planning and design processes. The application of these recommended methods to the road planning and design processes may guarantee the change from the current supplier-oriented schemes to the new user-oriented one. Also, this study suggests to reset objectivity and clarity of road construction process, to make conciliation guidelines based on many practical cases that produced good results, to introduce public involvement techniques in a stepwise basis, and to foster the professionals via education and training programs.

• Journal of Korean Home Economics Education Association
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• v.21 no.2
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• pp.139-158
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• 2009

The purposes of this study are to develop cyber home study program on consumer life for youth in middle school students and to compare the learning effect of this program with that of teacher's off-line lecture in class. The contents of the middle school Home Economics. Technology textbooks was analyzed. Based on this analysis 4 cyber home study lesson plans on youth's consumer life were developed. The topics of lesson plan were as 'youth and consumer behavior', 'utilizing consumer information'. 'effective consumer choice', 'resolving consumer problems'. The cyber home study were composed of 5 steps which were 'guiding' $\rightarrow$ 'learning activities' $\rightarrow$ 'evaluation' $\rightarrow$ 'further study' $\rightarrow$ 'summery'. The second grade middle school students as an experimental group participated in cyber home study through on-line class. The control group of students who had same condition with the experimental group were taught by home economics teacher using traditional instructional methods in off-line class. After the experiment, the changes in consumer's attitudes and knowledge of both groups were analyzed using Analysis of Covariance. The significant improvements of consumer's attitudes and knowledge were found in both the experimental and control groups of students. However, the consumer's attitudes and knowledge of the students who were taught by the teacher in off-line class improved more than those of the students who studied using cyber home study program in on-line class. Thus, the following conclusion is made that the cyber home study could be one of the useful learning methods to aid traditional off-line teaching in class.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.1
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• pp.1-10
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• 2004

The habit of finger sucking is a reflex occurring in the oral stage, due to nutritive and psychological desire. The habit of finger sucking is considered to be normal till 3 years of age. Dento-skeletal effect on maxillo-mandibular complex including occlusion is naturally correction, when habit stopped before 3 years. If finger sucking continues till $3{\sim}4$ years, Finger sucking leads to severe malocclusion and remarkable discrepancy maxillo-mandibular complex, which is difficult in expectation of natural correction. It is necessary to positive treatment. Treatment of malocclusion, as related to finger sucking is classified two methods. (psychological approach and orthodontic appliance) To stop a habit and to correct severe skeletal discrepancy and malocclusion, $fr\ddot{a}nkel$ appliance is very effective device. This study is to report two cases of treatment of malocclusion, as related to finger sucking. 2 years 10 months old girl with severe overjet, maxillo-mandibular skeletal discrepancy and severe convex facial profile was treated with a FR-II appliance. Finger sucking habit stopped immediately After 16 months, severe overjet, maxillo-mandibular skeletal discrepancy and severe convex facial profile was corrected. 4 years 2 months old girl with midline deviation, mandibular right shift, collateral posterior crossbite and facial asymmetry was treated with a FR-III appliance. Finger sucking habit stopped immediately. After 10 month, Midline deviation, mandibular right shift, collateral posterior crossbite and facial asymmetry were corrected. FR-appliance is a recommendable appliance for a habit breaker and correction of skeletal discrepancy.

• Journal of The Korean Association For Science Education
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• v.32 no.5
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• pp.805-822
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• 2012

The purpose of this study was to explore the patterns of group model development about blood flow in the heart and reasoning process by small group interaction. The subjects were 14, 8th graders in a Science Gifted Center. The group discussion was made possible by using triggering questions that can be answered based on experiences of hands-on activities such as a siphon pump analogy model activity and a dissection of pigs' hearts. Despite participating in same activities, the groups showed different model development patterns: unchanged, persuasive, and elaborated. Due to the critical revising, the group's explanatory model was elaborated and developed in the added and elaborated pattern. As critical revising is a core element of the developing model, it is important to promote a group interaction so that students become critical and receptive. The pedagogical analogy model and conflict situation enabled students to present elaborated reasoning. The Inquiry activity with the pedagogical analogy model promote students' spontaneous reasoning in relation to direct experience. Therefore offering a pedagogical analogy model will help students evaluate, revise and develop their models of concerned phenomena in science classroom. Conflict situation by rebuttal enable students to justify more solid and elaborate a model close to the target model. Therefore, teachers need to facilitate a group atmosphere for spontaneous conflict situation.

• Journal of the Korea Convergence Society
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• v.1 no.1
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• pp.41-47
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• 2010

This study was conducted to investigate determinent factors of the internet addiction that have influenced on middle school students. We randomly selected each one middle school in urban and rural areas, and conducted survey in 862 students of 2nd and 3rd grade from September 1 to 15, 2005. By using a statistical program called SPSS10.0, the data collected thereby were analyzed through a series of statistical methods including $x^2$-test, logistic regression analysis. The result of logistic regression analysis showed that the significant variables in urban area were resting time and using time a day. In rural area, sex, economic level, resting time and using time a day were significant variables. Higher status of internet addiction showed significant relationship with physical problems, anxiety, maladjustment to school, insufficient sleep time, fatigue in eyes, headache, pain in neck or shoulder, chronic fatigue, reduced vision, weight reduction, indigestion, xeroderma and adjustment to school. Especially, resting time and using time a day have dominant influence on internet addiction. And in case that the groups who showed high addiction tendency, there were negative health problem by physical, mental and social problem. To prevent internet addiction health education programs of right internet use and time, importance of rest, and health problems must be considered in internet addiction prevention policy.

• KDI Journal of Economic Policy
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• v.12 no.4
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• pp.21-46
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• 1990

This paper, a sequel to Yoo and Lee (1990), attempts to investigate the interindustry determinants of technical efficiency in Korea's manufacturing industries, and also to conduct an exploratory analysis on the stability of technical efficiency over time. The hypotheses set forth in this paper are most found in the existing literature on technical efficiency. They are, however, revised and shed a new light upon, whenever possible, to accommodate any Korea-specific conditions. The set of regressors used in the cross-sectional analysis are chosen and the hypotheses are posed in such a way that our result can be made comparable to those of similar studies conducted for the U.S. and Japan by Caves and Barton (1990) and Uekusa and Torii (1987), respectively. It is interesting to observe a certain degree of similarity as well as differentiation between the cross-section evidence on Korea's manufacturing industries and that on the U.S. and Japanese industries. As for the similarities, we can find positive and significant effects on technical efficiency of relative size of production and the extent of specialization in production, and negative and significant effect of the variations in capital-labor ratio within industries. The curvature influence of concentration ratio on technical efficiency is also confirmed in the Korean case. There are differences, too. We cannot find any significant effects of capital vintage, R&D and foreign competition on technical efficiency, all of which were shown to be robust determinants of technical efficiency in the U.S. case. We note, however, that the variables measuring capital vintage effect, R&D and the degree of foreign competition in Korean markets are suspected to suffer from serious measurement errors incurred in data collection and/or conversion of industrial classification system into the KSIC (Korea Standard Industrial Classification) system. Thus, we are reluctant to accept the findings on the effects of these variables as definitive conclusions on Korea's industrial organization. Another finding that interests us is that the cross-industry evidence becomes consistently strong when we use the efficiency estimates based on gross output instead of value added, which provides us with an ex post empirical criterion to choose an output measure between the two in estimating the production frontier. We also conduct exploratory analyses on the stability of the estimates of technical efficiency in Korea's manufacturing industries. Though the method of testing stability employed in this paper is never a complete one, we cannot find strong evidence that our efficiency estimates are stable over time. The outcome is both surprising and disappointing. We can also show that the instability of technical efficiency over time is partly explained by the way we constructed our measures of technical efficiency. To the extent that our efficiency estimates depend on the shape of the empirical distribution of plants in the input-output space, any movements of the production frontier over time are not reflected in the estimates, and possibilities exist of associating a higher level of technical efficiency with a downward movement of the production frontier over time, and so on. Thus, we find that efficiency measures that take into account not only the distributional changes, but also the shifts of the production frontier over time, increase the extent of stability, and are more appropriate for use in a dynamic context. The remaining portion of the instability of technical efficiency over time is not explained satisfactorily in this paper, and future research should address this question.

• Korean journal of applied entomology
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• v.57 no.2
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• pp.57-64
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• 2018

The fungus gnat, Bradysia difformis, has been recognized as an important pest of greenhouse crops. There is a need for research on the control of the fungus gnat. However, it is difficult to obtain many generations of the fungus gnat for several kinds of research. Indoor propagation is a very useful method for obtaining enough individuals in cases where the need is for larvae in soil. This study was conducted to determine the optimum growing media and temperature conditions for rearing the fungus gnat in the laboratory. Under experimental temperature conditions, hatching, pupation, and eclosion rates were the highest at $20^{\circ}C$. The developmental period of the fungus gnat was shortened with higher temperatures. The greatest number of eggs was an average of 144 at $20^{\circ}C$. Using different types of larvae growth media, the highest hatching rates were 84.7 and 84.4% in water agar and potato disks, respectively. The larval period was the shortest, at 14.7 days, when grown on potato disks. The highest pupation and eclosion rates were 85.2 and 82.6% on potato disks, respectively. The highest number of eggs was an average of 125.6 on potato disks. Regarding the effects of different growth media on the eclosion rate of B. difformis, the highest eclosion rate was 88.4% on the soil mix, and was 50% on oatmeal, 25% on shredded potato. The results of four different inoculation levels of larvae on eclosion rate of B. difformis showed that the highest eclosion rate was 84.7% for 1,000 larvae. The eclosion rate was shortened with a higher number of larvae inoculated/cage. In the growth medium used, 3,000 eggs were better for the initial level of inoculation, showing a relatively high emergence rate and short developmental period. Mass rearing procedures were explained in detail.

• Journal of Agricultural Extension & Community Development
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• v.20 no.3
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• pp.777-822
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• 2013

This study attempts to elicit the organizational strategy and operational elements of community-based agricultural management bodies as new main farm management. We analyzed the newest discussion trend, cooperated community management, between Republic of Korea and Japan based on theory of organizing regional agriculture, and also researched on the organization management and business management about cooperated management of community. In this study, the main conclusion of the organizational strategy and operational elements of community-based agricultural management bodies are as following. i) The community-based agricultural management bodies is the cooperation managed individual agriculture resources as joint stock for purposing compound goal, an expansion agricultural income, maintenance farm productivity and rural societies. ii) The domain of cooperative management focus on secondary and tertiary industry like food process, farm produce distribution, rural experience more than farm produce production. The study suggest business promotion system of village unit farmers groups, element of organization management as executive decision organization, business management, operating factor for each steps and management element of cooperation farm working. iii) The policy direction for invigoration community-based agricultural management bodies is to make facilitation for each steps instead of standardized support.

• Journal of The Korean Association For Science Education
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• v.22 no.4
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• pp.906-921
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• 2002

The purpose of this study was to survey the students' career choice related to science. Important factors of career choice were identified through factor analysis. 'Perception of career related to science', 'preference for science learning' and 'participation in science-related activity' were three main factors of science-related career choice. Students' responses to the three main factors were compared according to their career choice, grade and gender using ANOVA. Regression analysis was adopted to find out the relative importance among the three main factors. The subjects were 947 grade 6, 9 and 11 students in Seoul. Numbers of boys and girls in each grade was almost same. The questionnaire was developed to know the factors of students' science-related career choice after preliminary research and literature survey. The ratio of science-related career choice was not high (26%). Students' responses to and the relative importance of the three main factors differed with the grade and gender. From the results, making students have preference for science and giving them more opportunities of science-related activity is more important than making them have positive perception of science-related career. It is required to make a material for science career education considering the differences of age and gender using this study results.