• Journal of Aerospace System Engineering
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• v.9 no.1
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• pp.1-6
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• 2015

A critical speed analysis of oxidizer pump was peformed for a 7 ton class liquid rocket engine as the third stage engine of the Korea Space Launch Vehicle II. Based on the previously developed experimental 30 ton class turbopump and presently developing 75 ton class turbopump for the first and second stage rocket engine of Korea Space Launch Vehicle II, a layout and configuration of the 7 ton class turbopump rotor assembly are determined. A ball bearing stiffness analysis and rotordynamic analysis are performed for both of the bearing unloaded condition and loaded condition. Structural flexibility of the oxidizer pump casing is also included to predict critical speeds. From the numerical analysis, it is confirmed that the rotor system acquires sufficient separate margin of critical speed as a sub-critical rotor even though decrease of critical speed due to the casing structural flexibility.

• Fashion & Textile Research Journal
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• v.13 no.2
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• pp.215-225
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• 2011

The purpose of this study is to identify the differences in persuasive effectiveness of visual merchandising according to merchandise class. For the experiment, 8 stimuli brands were selected. A total of 360 questionnaires were obtained from college students. The results were as follows. First, VM cognition were divided into 3 factors by confirmatory factor analysis: coordination, attractiveness, and function. Second, coordination and function had a positive effect on brand attitude. Third, brand attitude had a positive impact on brand loyalty. Fourth, it was revealed that merchandise class had a moderating role in the influence of VM cognition on brand attitude. This study has a meaning in that the theoretical extension of previous studies on VM was executed and demonstrated the moderating role of merchandise class when brand attitude was formed by VM cognition.

• Journal of Korean Elementary Science Education
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• v.30 no.1
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• pp.1-9
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• 2011

The purpose of this study was to analyze elementary school teachers' teaching style and elementary school students' science anxiety according to teachers' teaching styles for science class. Data were gathered through the teaching style test and the science anxiety test. The teaching style test was taken in 293 elementary school teachers and the science anxiety test was taken in 1,523 elementary school students. The results were as followings: First, elementary school teachers' teaching style for science class were most in provider, expert and least in enabler. Second, elementary school students' science anxiety according to elementary school teachers' teaching style for science class were highest in facilitator and lowest in Enablers. There were significantly differences in science anxiety according to the teaching styles in elementary school. Third, elementary school students' science anxiety increased as grade goes up.

• Education of Primary School Mathematics
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• v.4 no.2
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• pp.139-150
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• 2000

The objectives of the current study are first, to compare and analyze the two different teaching methods of elementary mathematics in the traditional method and in the constructivists view, and, second, thereby to reveal possible problems of the present teaching practice and to suggest some guidelines to solve those problems.The results of this research are as follows: First, longer time was spent to reach the target pont of class because the class was a little bit disturbed and noisy due to a large amount of student activities in the beginning of the class in the constructive view. Second, in the class in the constructive view, the teacher should be able to respond appropriately to the situation where the students were cognitively. And the teachers sufficient preparation for the class was found essential to have the students reach the target point by themselves through identifying children`s minds. Third, the class in the constructivists view provide the teaching environment were the teacher could evaluate each students ability accurately and study progress of the class. And fourth, finally, it was not easy for the teacher to pay attention individually to each student in the current situation of large class, The effort to have more concern for students seems to contribute to opening student`s closed minds and to forming positive attitudes toward mathematics.

• Journal of electromagnetic engineering and science
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• v.10 no.1
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• pp.6-12
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• 2010

In this paper, highly efficient class-F power amplifiers(PAs) with harmonic-controlling transmission lines(TLs) were built for cellular and WLAN applications at 840 MHz and 2.4 GHz each. Also, based on these single-band PAs, a dualband class-F PA was designed after a careful investigation into the harmonics of the two frequencies. The harmonic-controlling TL was designed for the class-F operation at dualband by switching the length of the shunt $\lambda$/4 TL part, while the series $\lambda$/4 TL is optimized for both frequencies. To verify the performance, two class-F PAs optimized at each frequency and a dualband class-F PA at the corresponding frequencies were built with the secondand the third-harmonic control circuits at each frequencies. As a result, the PA#1 at 840 MHz has a peak drain efficiency of 81.2 % with an output power of 24.4 dBm, while the PA#2 at 2.35 GHz shows a drain efficiency of 94.5 % with an output of 22.8 dBm. Finally, the dualband class-F PA#3 showed 60.5 % and 50.9 % drain efficiencies at 840 MHz and 2.4 GHz, with powers of 23.8 dBm and 19.62 dBm, respectively.

• The Korean Journal of Community Living Science
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• v.26 no.1
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• pp.145-154
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• 2015

This study examines the effects of evaluation criteria for natural cosmetics on purchase and word-of-mouth intentions according to the LOHAS class. A survey was conducted from Feb. 2 to 17, 2013 and a total of 410 responses were analyzed using SPSS 18.0. The results of this study are described below. First, evaluation criteria for natural cosmetics had four dimensions - practical, aesthetic, promotional, and social criteria. Second, for the upper LOHAS class, all four dimensions of evaluation criteria for natural cosmetics were important relative to the middle and lower classes. Third, for the upper and middle LOHAS classes, purchase intentions were influenced by practical criteria. However, evaluation criteria had no effect for the lower LOHAS class. Fourth, the upper LOHAS class considered practical criteria, the middle LOHAS class considered practical and social criteria, and the lower LOHAS class considered aesthetic criteria, As a result, word-of-mouth intentions were influenced by evaluation criteria for natural cosmetics.

• Korean Journal of Child Studies
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• v.37 no.2
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• pp.13-25
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• 2016

Objective: The purposes of this study were to examine the effects of school-age children's ego strength, failure tolerance, and performance anxiety on their school class adjustment, and to model the relation structure of the variables. Method: For these purposes, a questionnaire survey was conducted with 562 6th graders. Results and Conclusion: The results of this study are summarized as follows. First, ego strength, failure tolerance, and performance anxiety were significantly different according to gender. Second, in male students, ego strength, failure tolerance, and performance anxiety had a significant direct effect on school class adjustment. In addition, ego strength and failure tolerance had a significant indirect effect on school class adjustment. Third, female students' paths to school class adjustment were similar to male students' but the effect of failure tolerance on performance anxiety and the effect of performance anxiety on school class adjustment were not significant. Fourth, in the results of multi-group analysis, the effect path from ego strength to school class adjustment was different between male and female students, and the effect was higher in female students than in male students.

• Smart Structures and Systems
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• v.6 no.4
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• pp.405-421
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• 2010

This paper proposes a method for early warning of hazard for pipelines. Many pipelines transport dangerous contents so that any damage incurred might lead to catastrophic consequences. However, most of these damages are usually a result of surrounding third-party activities, mainly the constructions. In order to prevent accidents and disasters, detection of potential hazards from third-party activities is indispensable. This paper focuses on recognizing the running of construction machines because they indicate the activity of the constructions. Acoustic information is applied for the recognition and a novel pipeline monitoring approach is proposed. Principal Component Analysis (PCA) is applied. The obtained Eigenvalues are regarded as the special signature and thus used for building feature vectors. One-class Support Vector Machine (SVM) is used for the classifier. The denoising ability of PCA can make it robust to noise interference, while the powerful classifying ability of SVM can provide good recognition results. Some related issues such as standardization are also studied and discussed. On-site experiments are conducted and results prove the effectiveness of the proposed early warning method. Thus the possible hazards can be prevented and the integrity of pipelines can be ensured.

• Journal of Korean Home Economics Education Association
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• v.13 no.1
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• pp.39-53
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• 2001

The purpose of this study is to develop lesson plan and to evaluate its application for the chapter of 'family life and housing'in the class of Home Economics in the third grade of middle school through the application of the Universal Design. This study has been done in three phases : analysis. development. and evaluation phase. The results of this study were as follows : First. in the development of the concept of the Universal Design. the objective of learning aimed to build the housing and utilities for all family members. Moreover. the various learning materials such as computer program. video materials. and worksheets of the group work were utilized to enhance the effectiveness of the lesson plan. Second. the evaluation of the students was examined through the assessment of the concept of the design. and the degree of class participation of student at the end of class. The LT cooperative learning as an instructional method was perceived to be appropriate and the participation of the cooperative work was also enhanced. The use of the computer programs. and video tapes was considered to be useful. Third. the response of the teachers was found to be both positive and negative. Teachers'positive reactions indicated that the use of the Universal Design facilitated student's participation in class stimulating their motivations and creative ideas not only in the classroom but also in the real life as for the negative reactions. teachers perceived understanding of the concept of the Universal Design. the activities of the students and class hours were relatively shout. These should be added to by the further study with the teachers endeavor.

• Journal of the Korean Society of Earth Science Education
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• v.3 no.3
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• pp.175-183
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• 2010

The purpose of this study was to examine about effect for class of disadvantaged gifted student. For this, twenty-one item-questionnaires were giver to fifty three students at third graders in four elementary gifted schools located in Ulsan. The result of this study were as follows: First, the elementary school cognitive aspects of disadvantaged gifted class from the result of the effectiveness, 3rd grade students surveyed were all positive. Most of the students about help in learning, record enhancement, presentation skills, resources utilization, problem solving, study skills, creativity and confidence in learning in 77.3% of students answered that they had a positive influence Second, the elementary school affective aspects of disadvantaged gifted calss from the result of the effectiveness, 3rd students surveyed were all positive. Most of students about study habits, attitude, interest in studying, studying aspects related to the confidence and positive in 67.3% of students answered that they were affected. Third, the elementary school social and cultural aspects of disadvantaged gifted class from the result of the effective, 3rd students surveyed were all positive. Most of the students about teachers, students, parents, and efficient use of time for study 70.9% of students answered that they had a positive influence. Fourth, the elementary school private aspects of disadvantaged gifted class from the result of the effective, 3rd grade students surveyed were all positive. Most of the students about reliance on private tutoring classes, interest, record enhancement in 65.1% of students answered that they had a positive influence.