• Journal of the Korean Geotechnical Society
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• v.27 no.9
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• pp.67-76
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• 2011

Bearing capacity of pile foundations in cold region is dominated by adfreeze bond strength between surrounding soil and pile perimeter. Adfreeze bond strength is considered to be the most important design parameter for foundations in cold region. Many studies in last 50 years have been conducted to analyze characteristics of adfreeze bond strength. However, most studies have been performed under constant temperature and normal stress conditions in order to analyze affecting factors like soil type, pile material, loading speed, etc. In this study, both freezing temperature and normal stress acting on pile surface were considered to be primary factors affecting adfreeze bond strength, while other factors such as soil type, pile material and loading speed were predefined. Direct shear box was used to measure adfreeze bond strength between Joomoonjin sand and aluminium because it is easy to work for various roughness. Test was performed with temperatures of > $0^{\circ}C$, $-1^{\circ}C$, $-2^{\circ}C$, $-5^{\circ}C$, and $-10^{\circ}C$ and vertical confining pressures of 1atm, 2atm, and 3atm. Based on the test results, the effects of temperature and vertical stress on adfreeze bond strength were analyzed. The test results showed that adfreeze bond strength increases with decreased temperature and increased vertical stress. It was also noted that two types of distinct sections exist, owing to the rate of increase of adfreeze bond strength along the change of freezing temperature: 1)rapidly increasing section and 2)gradually decreasing section. In addition, the results showed that a main factor affecting adfreeze bond strength switches from friction angle to adhesion as freezing temperature decreases.

• Journal of the Korean Geotechnical Society
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• v.29 no.12
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• pp.57-67
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• 2013

Micropile technology has evolved continuously since its instruction by Fernando Lizzi in the 1950s. The effects of group micropile have been researched by many researchers. The effects of group micropile differ and change with pile length, pile spacing (S), pile angle (${\theta}$) and pile embedded conditions. In the present study, the effects of resistance increase and settlement reduction from micropiles were investigated through a series of axial load tests. For the study, axial load tests were performed using mat, group micropiles and micropiled-raft (MPR) in various pile spacing and pile angle conditions. As the result, the effects of resistance of micropiled-raft were 80% (3D) to 110% (7D) of the total resistance of mat and group micropile. The effects of settlement restraint of micropiled-raft were 20% (S=3D, ${\theta}=45^{\circ}$) to 70% (7D, ${\theta}=15^{\circ}$) of settlement of mat foundation.

• Korean Journal of Construction Engineering and Management
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• v.12 no.5
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• pp.71-80
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• 2011

Flying net should be installed on every 3 or 4 construction floor from 8m above ground according to the rule. In the apartment housing construction, flying net installation work has been recognized the most dangerous work among the whole works because a small mistake of labors might make their death accident. Sub-contractors specialized in flying net have been developing various flying net types. However, most works of installing flying net as working with the developed system are performed outside the apartment housing, so that the risk of fall in works of installing supports and unfolding net is still high. Furthermore, as using the previously developed flying net labors might bump into the frame or the wire rope for supporting so that it makes secondary accidents. The objective of this research is to produce the proto-type of anti-collision flying net system based on the result of problem analysis on the installation and detachment process and suggest the improved anti-collision flying net system, which is able to improve safety and field applicability by conducting field experiment and analyzing performance.

• Journal of Korean Public Health Nursing
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• v.12 no.2
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• pp.67-88
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• 1998

Present study was attempt to explore the relationship between perceived family support and depression and to emphasize the importance or needs of family support in psychological care especially among adolescents. Study subjects comprized of 308 high school students including vocational students in part, and data collection was done in the Kwangju City area in April. 1998. The Moos Family Environment Scale and the Zung's Self-Rating Depression Scale modified by investigators were used as measurement tools of 59 item questionnaire and in data analysis, statistical methods of T-test, ANOVA. and Pearson Correlation Coefficient were utilized. The study findings are as follows 1. The hypothesis of the study, 'the higher the degree of perceived family support among adolescents, the lower the level of depression', was supported (r=-0.4469, p<.001). 2. Some variables in demographic characteristics related to the degree of family support with statistical significance were school division of vacational vs non-vocational(t=-2.02, p<.05), age(f=5.47, p<.01), family monthly income (f=2.49, p<.05), mother's level of education (f=3.01. p<.05), residence at developmental stage (f=2.87, p<.05), personal problem of highest priority at present(f=7.73, p<.001), and family problem perceived by adolescents(f=7.38, p< .001). 3. Items In general characteristics related to the level of depression with statistical significance were sex(t=-2.91, p<.0l). mother's level of education(f=2.53. p<.05). residence at developmental stage (f=3.95. p<.0l). present personal problem of highest priority (f=3.68. p<.1l). and perceived in-family problem (f=4.58. p<.001). 4. The mean score of the degree of perceived family support was 61.26 $(SD=\pm14.45)$ in a range of 21.00 to 96.00 ; that of the level of depression. 43.74 $(SD=\pm8.04)$ in a range of 23.00 to 67.00. which demonstrated that the higher the degree of perceived family support, the lower the level of depression. In conclusion. it was found that the degree of family support perceived by adolescents is a variable affecting the level of depression. Based on the study outcome, further research suggestions can be made as such that repeated studies are needed in order to delineate the various factors affecting family support and depression, and a study involving family support implementation program is required as a nursing intervention for the development of emotional security among adolescents, perceived family support, depression, adolescence.

• Journal of the Korean earth science society
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• v.24 no.5
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• pp.440-448
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• 2003

We have performed 3-D geomagnetic induction Modeling considering with anomalous conductive structures to interpret the conductive anomaly proposed by previous studies on the Korean Peninsula. The results of modeling coincide well with the observed induction arrow. we confirm the fact that Imjin River Belt and Ogcheon Belt presumed in the model are reasonable. In the western-middle area of the peninsula (YIN, ICHN) the induction arrows seem to reflect the existence for the Imjin River Belt and the induction arrows in western-south area (HNS, CHY, DZN, MWN) is likely to reflect the effect of the Ogcheon Belt. The difference arrows, calculated by subtracting the sea effect from observed induction arrow in the western area of the peninsula at the period of 60-minutes, show little difference with the observed induction arrows. Especially, the difference arrows in YIN, ICHN also show a similar pattern to those at the periods longer than 10-minutes. These results strongly suggest that the Imjin River Belt and the Ogcheon Belt extend down to the deep part of the crust in spite of the limitation of our model.

• The Korean Journal of Financial Management
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• v.23 no.1
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• pp.1-47
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• 2006

This study investigated the effect of tender-offer on the value of the firms in Korea. For this purpose, the study applied an event study methodology to 55 cases(bidding firm : 26, target firm : 39) of tender-offer and 164 cases(bidding firm : 144, target firm : 20) of merger announcements made between January 1st, 1994 and September 30th 2004. We found the following results. For tender-offer announcements, there was a significant increase in target firm's value while there was no significant change in bidding firm's value. In contrast, for merger announcements, there was a significant increase in bidding firm's value while there was no significant change in target firm's value. In addition, the synergy effect of tender-offer was higher than that of merger. The results support the Berkovitch and Khanna(1991)'s prediction that bidding firms choose tender-offer rather than merger in the presence of higher synergy profit from M&A.

• Journal of The Korean Association For Science Education
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• v.23 no.2
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• pp.200-213
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• 2003

This study is one of the successive studies for investigating students' processes of generating and evaluating scientific hypothesis. In this study, I analyzed the characteristics of students' experimental design to test whether the given hypotheses were correct or not. As results, it was found that (1) 3 components (experimental method, prediction of the result of experiment, evaluation of hypothesis) were needed to complete description of the experimental design, (2) students tried to test hypothesis considered as being correct as well as hypothesis considered as being false by students, (3) student tried to confirm hypothesis, which was considered as being correct, based on theoretical approach rather than experimental approach, (4) students' experimental design could be classified as two types, that is, direct experimental testing and comparative experimental design, and the latter could be classified as two subtypes; positive comparative one and negative comparative one, (5) students showed tendency to design positive comparative experiment when they considered hypothesis as being correct, and vise versa, (6) students preferred the prediction which could confirm the hypothesis when they considered the hypothesis as being correct, and vise versa, (7) many students rejected contradicting prediction even though they did not actually conduct experiment yet.

• The Journal of Korean Academic Society of Nursing Education
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• v.10 no.2
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• pp.278-288
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• 2004

Purpose: Structural equation model was analysed to explore the determinants of health behaviors of university nursing students in Korea. Study subjects: Four hundreds seventy eight university nursing students were selected by random cluster sampling from five universities located in the middle area of Korea. Data collection: The data were collected by questionnaires about demographic characteristics, stressful life events, perceived social support, perceived health status and health behaviors. Results: 1. Living with(out) family did not show direct effect on health behaviors. 2. Stressful life events and social support showed indirect effect on health behaviors via perceived health status; higher score of stressful life events predicted negative health behaviors. 3. The higher score of perceived health status predicted positive health behaviors. Recommendation: To improve the health behavior of nursing student, the program for positive perceived health status is necessary, which includes the social support and stressful life event control program. Each nursing school should be encouraged to develop the program for increasing positive perceived health status. It would be more effective to develop health program separately according to the demographic or social characteristics of the students. And following studies could be suggested to identify and promote the validity and reliability of perceived health status and health behaviors measurements.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.4
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• pp.19-33
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• 2008

Dynamic response measurements from natural excitation were carried out for 25- and 42-story buildings to evaluate their inherent properties, such as natural frequencies, mode shapes and damping ratios. Both are reinforced concrete buildings adopting a core wall, or with shear walls as the major lateral force resisting system, but frames are added in the plan or elevation. In particular, shear walls in a 25-story building are converted to frames from the 4th floor level downwards while maintaining a core wall throughout, resulting in a fairly complex structure. Due to this, along with similar stiffness characteristics in the principal directions, significantly coupled and closely spaced modes of motion are expected in this building, making identification rather difficult. By using various state-of-the-art system identification methods, the modal parameters are extracted, and the results are then compared. Three frequency-domain and four time-domain based operational modal identification methods are considered. Overall, all natural frequencies and damping ratios estimated from the different identification methods showed a greater consistency for both buildings, while mode shapes exhibited some degree of discrepancy, varying from method to method. On the other hand, in comparison with analysis results obtained using the initial finite element(FE) models, test results exhibited a significant difference of about doubled frequencies, at least for the three lower modes in both buildings. To improve the correlation between test and analysis, a few manual schemes of FE model updating based on plausible reasons have been applied, and acceptable results are obtained. The advantages and disadvantages of each identification method used are addressed, and some difficulties that might arise from the updating of FE models, including automatic procedures, for such large structures are carefully discussed.

• Journal of the Economic Geographical Society of Korea
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• v.16 no.1
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• pp.118-134
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• 2013

This paper analyzes the pubic nature of New Genre Public Arts. It is very sensitive to the social issues and supports democracy and communities with the diverse civic participation. Therefore, it is be widely known without doubt that new genre public arts is more public in nature compared to the previous public arts. This research observes the practices of new genre public art and focuses on the problems of the revealing nature of new genre public art through the analysis of the interrelations among government, artists, and the residents by through observation on the , Seoul City Gallery project from October 2008 to January 2009. The implementation of the project is divided into three constituent parts: local government for funding, artists for planning and implementing, and residents. Local government supports and commands the public art works to create more competitive and harmonious city. Artists emphasize the revitalization of community and take the residents as the passive objects of enlightenment. Whereas, the residents hope to use the funds to improve economic conditions. Artists accept the top-down commands of government, whereas residents tend to passively participate and become objects for enlightenment by artists, after all, might be alienated by the project. These kinds of communications and relationships raise the issue of the possibility of failure of public arts projects.