• Korean Journal of Agricultural Science
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• v.31 no.2
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• pp.105-114
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• 2004

This study was performed to examine the physical and mechanical properties of eco-concrete using soil, natural coarse aggregate, soil compound and polypropylen fiber. The mass loss ratio was decreased with increasing the content of coarse aggregate and soil compound. The compressive strength, flexural strength, ultrasonic pulse velocity and dynamic modulus of elasticity were increased with increasing the content of coarse aggregate, soil compound and polypropylene fiber. The compressive and flexural strengths were showed in 8.07 MPa and 2.641 MPa at the curing age 28 days, respectively. The coefficient of permeability was decreased with increasing the content of coarse aggregate and soil compound, but it was increased with increasing the content of polypropylene fiber. The lowest coefficent of permeability was showed in $5.066{\times}10^{-9}cm/s$.

• Journal of the Korean Society of School Health
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• v.13 no.2
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• pp.231-240
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• 2000

The purpose of this study is to analyze the relationship between life style and health status of the staffs of an elementary school to understand exercise practices and life styles and to analyze the self-efficacy and the factors that affect it concerning walking exercise. The subjects were m9 staff member of the 10 elementary school in Seoul and materials were collected through an organized examination table from October, 1999 to May 2000. The people health awareness table was used as a variable for life style, the 13 questionnaires made of a 5 points measure was for the self efficacy concerning walking exercise. The data was analyzed through a statistics package made of a Chisquare-test, t-test, ANOVA and a regression analysis. The major results of this study were as follows; 1) 50% of the staffs were practicing regular exercise, 3/4 of them practiced walking, jogging and mountain climbing that don't need equipment and exercise frequency was 1-2 times per week 64%. of the time and exercise span was under 30 minutes in 38%, the highest 2) The average of self-efficacy concerning walking exercise was 3.6 points but the answers "I can walk enough to be in a sweat", "I can walk according to my exercise plan" were relatively low. 3) The explanation degree of the Model was 14% in a regression analysis between self efficacy concerning walking exercise and as a dependent variable for a regular walking exercise plan, regular health examination, routine health status, and breakfast might serve as an explanation degree. According to the results of this study, the suggestions were as follows: 1) The chronic invalid was not enough in the change of life style after chronic disease, most of all, it need the awareness of change, of active health education and of public information for health promotion action practice through the prohibition of smoking, abstinence from drink, exercise and nutritional balance. 2) Concrete practice program enlargement is needed to enhance related walking exercise or of a type lecture meeting for subjects who have a positive attitude about walking exercise plans. 3) A program that can actively recommend a health promotion life style is needed when we make allowance for those who have an ordinarily healthy life style and show a high walking exercise self-efficacy.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.5
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• pp.511-520
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• 2007

There is a concern with worldwide deterioration of highway bridges, particularly reinforced concrete. The advantages of fibre reinforced plastic(FRP) composites over conventional materials motivate their use in highway bridges for replacement of structures. Recently, an FRP deck has been installed on a state highway, located in New York State, as an experimental project. In this paper, a systematic approach for analysis of this FRP deck bridge is presented. Multi-step linear numerical analyses have been performed using the finite element method to study the structural behavior and the possible failure mechanism of the FRP deck-superstructure system. Deck's self-weight and ply orientations at the interface between steel girders and FRP deck are considered in this study. From this research, the results of the numerical analyses were corroborated with field test results. Analytical results reveal several potential failure mechanism for the FRP deck and truss bridge system. The results presented in this study may be used to propose engineering design guideline for new and replacement FRP bridge deck structure.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.16-24
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• 2018

In this study, an experiment was conducted to analyze mortar based rheology for 3D printing method application. The tendency of rheological properties due to the change of W/B, binder type, replacement ratio, and super plasticizer which have a great influence on the flow characteristics of concrete was experimentally analyzed. Experiments were carried out by dividing into paste and mortar. In the paste experiment, rheology was analyzed by setting W/B, binder type, replacement ratio, and super plasticizer dosage as main variables. In the mortar experiment, the rheological properties of W/B and sand ratio were analyzed. As a result, as the W/B was increased, the viscosity decreased and the FA ratio to replace FA increased and the viscosity increased. In order to increase the fluidity, substitution of only 5% of SF reduces the shear stress and the viscosity is reduced by about 83%. Mortar rheological evaluation shows that there is a critical section where a large change occurs in the W/B 30 to 40% section. Also, in the same W/B, it is analyzed that there is a critical section where the shear stress increases more than twice in the sand ratio of 50~60%.

• Korean Journal of Construction Engineering and Management
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• v.5 no.6 s.22
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• pp.212-217
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• 2004

Carbon fiber reinforced plastic(CFRP) plate Is one of the alterative materials for soengthening of reinforced and prestressed connote members due to excellent strength and light weight In this paper, the behavior of beams strengthened with CFRP plate and CFS(Carbon fiber sheet) is observed and analyzed from the test results. Especially specimens with thick plate is tested when large moment and large shear lone appear in same position. The main failure mode is a peeling-off of the CFRP plate near the loading points due to flexural-shear crack, Because of this failure mode, failure load is not linearly proportional to the thickness of CFRP plates. When beam is wrapped with CFS around oかy loading point it does not influence on the failure loads. Depending on the loading pattern, it is necessary to consider different design criteria for reinforced concrete members with external reinforcement. When line moment and large shear force appear in same location, maximum thickness may limit to 0.6mm and ratio between moment of strengthened beam and moment of unstrengthened beam is proposed 1.5-2.0. In order to use the plate of thicker than 6mm, CFS may be extended to the location which moment of strengthened beam is 1.5 times than moment of unstrengthened beam.

• School Mathematics
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• v.4 no.3
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• pp.375-399
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• 2002

When a curriculum change is being an issue, the editorships and the promotive directions reflect to supplement the social requests. However it is often criticized that such changes in the textbook itself are not satisfactory enough as to coherent to the editoships. And we set the following research questions; (1) One of the most important changes in the new 7th curriculum is to encourage the students' activities. We checked if it is well suited in the new textbooks. (2) Often textbook itself is not important In class, while instructor or students want something else other than the one suggested in the textbook. We asked 187 teachers how they use the textbooks in class. To answer (1), we checked up the introductory - activity - contents with 7 categories, which are ${\circled1}$ of real life sources ${\circled2}$ in use of concrete manipulative ${\circled3}$ in use of computers or calculators ${\circled4}$ in use of historical resources ${\circled5}$ stimulating to recall a relevant previous knowledges ${\circled6}$ of coherence between the activity and the exploratory contexts. ${\circled2}$ were increased, rewarding to the decrease of ${\circled5}$, in the new textbooks, while changes in ${\circled3}$ and ${\circled4}$ were not enough to talk about increments. Especially slight decrease in ${\circled6}$ were detected and it seemed to attribute to the unmatchable use of ${\circled1}$ and ${\circled2}$ with the explanation of mathematical subjects, which also implies how difficult to match ${\circled1}$ and ${\circled2}$ with ${\circled6}$. Analyzing the reponses of (2), about 70% of the teachers used the introductory activities in the textbook, which led better attention of sudents, while 30% of teachers do not use it because they felt that its inroductory activities had not been adequate for their purposes. Teachers counted inadequacy reasons for not being helpful in class, lack of time or lack of support of students, etc. Those teachers use introductory activities invented of their own for classes. As some results of the study, we suggest firstly that authors of textbooks have to get more informations to provide ways to entcourage students' interest in mathematics classes. The ways must be practical and brain storming as well as More use of computers and calculators and mathematical history are expected. Secondly, we are emphasizing the feedbacks between the textbook authors and the users(teachers and students) through internet. Which, we anticipate, will get better communications between them and be a good foundations of continuous modifications of textbooks.

• Journal of Elementary Mathematics Education in Korea
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• v.14 no.2
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• pp.487-521
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• 2010

The purpose of this study was to investigate and analyze the effect of mathematics teaching experience during the teaching practicum on pre-service elementary teachers' beliefs about mathematics. The conclusions drawn from the entire research were, as follow: First, it can be said that mathematics teaching experience during the teaching practicum has a significant effect on the change of pre-service elementary teachers' beliefs about mathematics. Specifically, the teaching experience during the teaching practicum has statistically significantly negative effects(p=.05) on pre-service elementary teachers' beliefs about the teaching mathematics. Second, the factors which help pre-service elementary teachers the most in preparing for mathematics classes are collaborating teachers in charge of supervising them, the teacher's guidebook and materials acquired from the Internet. Third, pre-service elementary teachers are well aware of the importance of understanding students and emphasize concrete manipulative activities, but experience lots of failures due to difficulty of drawing students' attention. Fourth, collaborating teachers do not play a significant role in helping pre-service elementary teachers develop and change their beliefs about mathematics positively. The advise given by collaborating teachers to pre-service elementary teachers is mostly about simple techniques of managing the classroom. So, collaborating teachers do not affect significantly and positively on the change of pre-service elementary teachers' beliefs. Fifth, regardless of their belief tendency, pre-service elementary teachers teach more confidently and feel more satisfactory when they prepared for classes more thoughtfully and understanded students more deeply.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.2
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• pp.59-71
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• 2006

Due to the rapid process of industrialization the cities of Korea confront changes of climate, destructions of the habitate and decrease of the green. Recently Seoul and other local governments have implemented policies and projects to improve the environmental surroundings. In reality, however, those policies and projects face difficulties in the course of implementation. The fact that there are no concrete regulations and specific legal procedures turns out to be one of the main difficulties. The aim of this study is to present specific plans and methods of wall-planting and to provide basic guidelines for the future direction of wall-planting and offer ideas of facilitating wall-planting. This study is based on questionnaires from specialists of landscape architecture through individual interviews and/or e-mails. The questionnaire is consisted of following 4 sections. 1. Show the experts current regulations and/or legal procedures and ask them improvements and suggestions. 2. Ask them choose matters of the highest priority by using Ricardo's diagram method. 3. Ask them to make a graded list in terms of the location and method of wall-planting. 4. Study the maketability of the wall-planting products currently in circulation. The city of Seoul and the Ministry of Environment recommend that trellis and/or planting inducement structures be installed on the building wall by regulation. The specialists responded to the questionnaire advocate that green wall without trellis should be allowed as green zone. Therefore regulations concerning the wall-planting should be determined specifically according to the characteristics of individual plants and walls. It has been urged that legal aid and social support must be reinforced to establish rules dealing with wall-planting. The respondents also point out that significant cutting down of the tax is far more effective in accelerating the wall-green instead of administrative support. The highest priority in terms of planting has been given to sound-proof wall, retaining wall and building wall. Concerning the maketability of the wall-planting products, panel products are recommended for early-planting and building planting. It has been suggested that the research and study of new materials and species be done in advance.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.12 s.159
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• pp.1737-1746
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• 2006

The purpose of this study is to present a concrete image of the ideal beauty as shown in era preceding 1945 that effects the shaping of our aesthetic values; by analyzing its characteristics through the covers of women's magazines of that period, this research aims to promote the understanding of beauty of the human body. The scope of my research extends throughout the collection of women's magazines stored in the National Library and the Korea Magazine Information Center. The gathered research materials are: 5 kinds of Shin-Yeo-Sung (신여성), 51 kinds Yeo-Sung(여성) and 30 kinds of Ga-Jung-Ji-Woo(가정지우). The result of the research could be summarized as the followings. Before the 1920's in response to the violent opening, there was a trend of sticking to the traditional standard. In the 1920's, the prevalent images of women were meek and fragile. Japanese standard of beauty was explicitly indicated. In the 1930s, as Western movies started to be shown to the general public, western features were idealized and furthermore intelligence was required as a further condition. In the 1940s, preparation of the war led to encouragement of images of motherhood and natural beauty, and resistant to this trend led to pseudoclassicism.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.474-480
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• 2018

FRP is a new material that is lightweight, has high strength and high durability, and is emerging as a third construction material in many countries. The composite material panel targeted in this study was a curved member and is the most frequently used arch-shaped member of a structures, such as tunnels. Composite curved panels can be produced in high quality and large quantities through automation operations. On the other hand, the frequency of application is low, and the design criteria and experimental data are lacking. Therefore, this study examined the mechanical performance of the member unit first to verify its performance as structural members of the FRP curved panel. For this purpose, tensile, compression, and connection performance tests were carried out. The tensile tests showed greater tensile strength of specimens with larger curvature, and the compression tests showed that the composite section of a composite material has greater compressive strength than the concrete section. Finally, the test of the performance of the connection showed that the attachment performance of the connection was more than equal to that of the FRP composite material panel.