• 대한지구과학교육학회지
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• 제5권1호
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• pp.95-104
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• 2012

The purpose of this study is to examine what effects the experiment class to stress discussion of small groups in scientific experiment class of the elementary school has on scientific achievement and attitude on the science of the students comparing to the usual scientific experiment class. For that purpose, this study has divided 49 students at the 6th grade of the M elementary school in P City into test groups of 24 students and control groups of 25 students. Classes have been progressed by giving sufficient time to the test groups for discussion by each small groups after experiment while by allowing the control groups to finish the experiment with arrangement of the experiment results. Conclusions of this study include: First, the more familiar the experiment materials are and the easier the experiment procedures are to be operated by the students, the more actively the small group discussion activities have been deployed. It shows that the students need a certain level of background knowledge before experiment for vital discussing activities. Second, it is appeared that the test groups given the scientific experiment class stressing small group discussing activity have significantly high scores comparing to the control groups given the existing scientific experiment class. It shows that the small group discussing activities have effects on promoting understanding of the students on the scientific achievement for the scientific experiment class. Third, it is appeared that the test groups given the scientific experiment class stressing small group discussing activity significantly high scores on attitude about the science comparing to the control groups given the existing scientific experiment class. It is considered that the students could have opportunities to compare their own thoughts with others and to have reflective thought to change their thoughts through the small group discussing activity. As shown above, it shows that the experiment class to stress discussing activities is more effective to increase scientific achievement and attitude about the science than the scientific experiment class to get and arrange the experiment results from the existing experiment classes.

• 대한치과기공학회지
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• 제43권4호
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• pp.186-193
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• 2021

Purpose: The purpose of the study was to determine the general characteristics of students in dental technology departments; the correlations among their immersion in learning, class satisfaction, and academic achievement; factors influencing online learning experience; ways to improve students' class satisfaction; and basic data for designing effective online courses. Methods: A total of 300 questionnaires were produced and distributed to dental technology students from September 29 through October 8, 2020. The outcome was analyzed using IBM SPSS Statistics ver. 25.0. A significance level of α=0.05 was used for reliable verification. Results: Immersion in learning, class satisfaction, and academic achievement were relatively high among students who studied on a regular basis, and class satisfaction and academic achievement were relatively high among students who studied with almost no interruption. Concerning the correlations between academic achievement, immersion in learning, and class satisfaction in online learning, the correlation between academic achievement and class satisfaction was the highest at r=0.862. Class satisfaction was the largest factor that influenced academic achievement, and the higher students' immersion in learning and class satisfaction were, the higher their academic achievement was. Conclusion: The research is a case study that investigated the general characteristics of dental technology department students and the correlations among their immersion in learning, class satisfaction, and academic achievement. The study outcome could be used in determining factors that influence online learning and designing effective online courses that improve learner satisfaction.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1444-1452
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• 2011

At present, Kyungbu high-speed railway is operated with 300km/h, Honam high-speed railway is being constructed with 350km/h, and the development for the overhead contact line system is to be conducted for the next-generation high-speed railway with the speed of 400km/h. It is necessary to set up the specification and criteria for the key parts such as dropper, termination clamp and tension insulator for the 400km/h railway line. In this paper, the specification and the criteria for dropper, termination clamp and tension insulator has been reviewed and proposed in order to secure long-term reliability and stability under the maximum speed of 400km/h. Also, the specification, criteria and international standards for 300km/h class and 350km/h class railway line system and the international standards related with the insulators have been reviewed, compared and analysed.

• 한국압력기기공학회 논문집
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• 제11권2호
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• pp.40-44
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• 2015

The fatigue behavior of thermal butt fusion in safety class III high-density polyethylene (HDPE) buried piping for nuclear power plants was investigated using load-controlled bending fatigue on four-point bend test specimens. Based on the results, the presence of thermal butt fusion beads was confirmed to reduce the fatigue lifetime in the low- and medium-cycle fatigue regions while having a negligible effect in the high-cycle fatigue regions.

• Journal of Power Electronics
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• 제12권5호
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• pp.699-707
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• 2012

This paper proposes a single-stage half-bridge electronic ballast with a high power factor using only a single coupled inductor. Compared to conventional high power factor electronic ballasts, the proposed ballast is a simpler circuit with a low cost and a high reliability. The proposed ballast is made up of a power-factor-correction (PFC) circuit and a self-oscillating class-D inverter. The PFC and inverter stages of the proposed ballast are simplified by sharing only a single coupled inductor and two common switches. The proposed PFC circuit can achieve a high power factor and low voltage stresses of the switches. A saturable transformer in the self-oscillating class-D inverter determines the switching frequency of the ballast. Experimental results obtained on a 30W fluorescent lamp are discussed.

• 한국조리학회지
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• 제23권5호
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• pp.159-168
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• 2017

This study was conducted to investigate the effects of high class korean restaurants' servicescape on customers' emotional response and intention to revisit. This study also examined the relationship among emotional and cognitive reactions and intention to revisit. A total of 216 questionnaires were analyzed using the factor analysis, reliability test, and structural equation modeling analysis. The results revealed that space, aesthetics and comfortableness were positively related to emotional reaction, and convenience and cleanliness were related to cognitive reaction. This study also found that intention to revisit was positively related to emotional and cognitive reactions. Moreover, it was found that think was positively related to emotional reaction, and feel, think, act and the related were positively related to cognitive reaction. Finally, cognitive reaction was positively related to revisit. The results of the study suggested that high-class Korean restaurant marketers should introduce or strengthen servicescape, brand reputation and experiences, which increased brand attitude or revisit.

• 한국초전도ㆍ저온공학회논문지
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• 제5권2호
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• pp.20-29
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• 2003

As power systems grow more complex and power demands increase, the need of underground transmission system is increasing gradually. But it is very difficult and high in cost to construct new ducts and/or tunnels for power cables in metropolitan areas. HTS (High Temperature Superconducting) cable can carry very high current densities with strongly reduced conductor loss and allow high power transmission at reduced voltage. Therefore HTS cable can transfer more power to be moved in existing ducts, which means very large economical and environmental benefits. A development project for a 22kV class HTS cable is ongoing at a research centers, and the cable manufacturer in Korea. In this paper, we carried out investigation for application of 22kV class HTS cable in Korean utility networks. The results show that the HTS cable is applicable to replace IPB in pumping-up power plant, withdrawal line in distributed generation, withdrawal line in complex power plant, and conventional under ground cable. Finally, as the cost of HTS wire and refrigeration drops, the technical and economical potential of HTS cable is evaluated positively.

• 한국조리학회지
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• 제23권3호
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• pp.242-256
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• 2017

This study was conducted for the university students who majored in culinary arts. The effects of students' certifications on class and school life satisfaction and their effects on preparation employment were examined. The results showed that the students with the certifications had a high level of satisfaction in the class satisfaction, but they also had high stress in the school life. In other words, it seemed that the stress was increased in parallel with the school life in obtaining the certificate. In the case of qualification for preparation employment, the certification affects the preparation for employment even for the culinary arts majors. As for the number of certificates and passions, the change was found from 3 certifications, lower in 4, but again in 5. These results suggest that the certification initially increases enthusiasm, but when it reaches a certain level, it reaches its limit and it rises again after passing the interval. Also, students who graduated from cooking related high school showed high passion compared to those who did not.

• 한국가정과교육학회지
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• 제8권1호
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• pp.51-57
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• 1996

The purpose of this study were to examine the difference of the effect of CAI and students’attitude to Home Economics Class through CAI. 120 girl students of the first year were chosen at B middle school in Daegu. Among them each 30 students were classified into 4 groups； High Intelligence group/Individual learning pattern, High Intelligence group/Small group learning pattern, Low Intelligence group/Individual learning pattern, Low Intelligence group/Small group learning pattern. The task of learning was “management of washing”Unit of the second grade. The data were processed with Cronbach’s ${\alpha}$, t-test, ANOVA by SPSS/PC(sup)+. The research findings are as follows： 1. In the verification of CAI Learning effect according to student group pattern, there is no difference between Individual learning pattern and Small group learning pattern in Achivement and Retention of learning. 2. In the verification of CAI Learning effect according to student intelligence level, there is no difference between High Intelligence group and Low Intelligence group in Achivement and Retention of learning. 3. The result of students’attitude to Home Economics Class verificated is an follows. (1) Individual learning pattern is more attensive than Small group learning pattern, but there is no difference in Intelligence level. (2) Low Intelligence group is more positive than High Intelligence group, and Small group learning pattern is more positive than Individual learning pattern in a view of Home Economics Class after using CAI.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.123.2-123.2
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• 2010

Fuel Cell cogeneration system is a promising technology for generating electricity and heat with high efficiency of low pollutant emission. We have been developed 5kW class fuel cell cogeneration system for commercial and residential application. The fuel processor is a crucial part of producing hydrogen from the fossil fuels such as LNG and LPG. The 5kW class high efficiency fuel processor consists of steam reformer, CO shift converter, CO preferential oxidation(PrOx) reactor, burner and heat exchanger. The one-stage CO shift converter process using a metal oxide catalyst was adopted. The efficiency of 5 kW class fuel processor shows 75% based on LHV. In addition, for the purpose of continuous operation with load fluctuations in the commercial system for residential use, load change of fuel processor was tested. Efficiency of 30%, 50%, 70% and 100% load shows 75%, 75%, 73% and 72%(LHV), respectively. Also, during the load change conditions, the product gas composition was stable and the outlet CO concentration was below 5 ppm. The Fuel processor operation was carried out in residential fuel cell cogeneration system with fuel cell stack under dynamic conditions. The 5kW class fuel processor have been evaluated for long-term durability and reliability test including with improvement in optimal operation logic.