• Journal of the Korean Geotechnical Society
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• v.22 no.4
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• pp.95-104
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• 2006

For the interests in the economical and safe design of foundation system, the concern on the piled raft or disconnected piled raft foundation system is increasing now. In this study, the behavior and the effects of the disconnected piled raft foundation not studied actively in this country were examined using the triaxial compression tests in place of laboratory model tests. The triaxial test samples were prepared with Jumunjin standard sand and the carbon rods, which simulate the ground soil and piles respectively. After the sample in which carbon rods were arranged was laid inside the triaxial chamber, the confining pressure was applied and then loading test was conducted. To analyze the reinforcing effects of the disconnected piled raft foundation, a few number of tests were carried out by changing the number, the diameter and the length of the model piles. As a result of this study, in the disconnected piled raft foundation system, even though the number of pile is few and the diameter of pile is small, the settlement of the foundation system decreased greatly.

• Journal of the Korean Geotechnical Society
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• v.26 no.12
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• pp.41-50
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• 2010

The behavior of laterally cyclic loaded piles is different from that of piles under monotonic loading and depends on soil and load characteristics. In this study, model pile load tests were performed using a calibration chamber to investigate the effects of load characteristics on the behavior of laterally cyclic loaded piles in sand. Results of the model tests show that the ultimate lateral load capacity of laterally cyclic loaded piles decreases linearly with increasing the number of cycles and increases slightly with increasing the magnitude of cyclic lateral loads. When the piles reach the ultimate state, the maximum bending moment developed in the piles decreases linearly with increasing the number of cycles and it occurs at a depth of 0.36 times pile embedded length for all the number of cycles. However, both the magnitude and depth of the maximum bending moment of piles in the ultimate state increase slightly as the magnitude of cyclic lateral loads increases. It is also observed that the cyclic lateral loading generates a decrease in the ultimate lateral load capacity and maximum bending moment for piles in the ultimate state. In addition, based on the model test results, a new empirical equation for the ultimate lateral load capacity of laterally cyclic loaded piles in dense sand is also proposed. A comparison between predicted and measured load capacities shows that the proposed equation reflects satisfactorily the model test results.

• Journal of the Korean Geotechnical Society
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• v.39 no.5
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• pp.27-40
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• 2023

A pile is a structural element that is used to transfer external loads from superstructures and has been widely utilized in construction fields all over the world. The method of installing a pile into the ground should be selected based on geotechnical conditions, location, site status, environmental factors, and construction costs, among others. It can be divided into two types: direct hammering and preboring. The direct hammering method installs a pile into the bearing layer, such as rock, using a few types of hammer, generating a considerable amount of pile driving-induced vibration. The vibration from pile driving influences adjacent structures and the ground; therefore, quantitatively investigating the effects of vibration is inevitably required. In this study, two-dimensional dynamic numerical modeling and analysis are performed using the finite difference method to investigate the influence on the adjacent slope, including temporary supporting system. Time-dependent loading induced by pile driving is estimated and used in the numerical analysis. Consequently, large surface displacement is estimated due to surface waves and less wave deflection, and refraction at the surface. The total displacement decreases with the increase of the distance from the source. However, lateral displacement at the top of the slope shows a larger value than vertical displacement, and the overall displacement tends to be concentrated near the face of the slope.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.2
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• pp.120-129
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• 2023

Marine structures are subject to damage not only from sea salt but also from the adhesion of marine microorganisms and suspended particles, which cause additional damages. In order to prevent this, periodic coating is employed in the case of vessels to maintain the necessary performance. However, it is true that periodic coating is difficult for concrete or steel support structures, and there is a risk of marine environmental pollution. In this study, authors developed an anti-fouling coating agent using eco-friendly materials that possess hydrophilic cellulose nanofibers and AKD(alkyl ketene dimer). To achieve a homogeneous mixture, the content of cellulose nanofibers was fixed at 1 %, and AKD, distilled water, and waste glass were mixed using a digital mixer and homogenizer. The contact angle of the prepared coated surface was observed to be over 130°, indicating sufficient performance even in a water droplet flow test with a 15° slope, suggesting self-cleaning capability. Furthermore, through the analysis of viscosity characteristics at different temperatures, it was confirmed that the application is feasible at room temperature. Microstructure analysis also verified that the coating agent is uniformly applied to the concrete surface.

• 한국체육학회지인문사회과학편
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• v.55 no.2
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• pp.47-67
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• 2016

The purpose of this study was to understand barriers and problems associated with physical activity of older adults in a small town and to provide improvement plans based on socio-ecological model. This study employed three independent phases including survey, accelerometer study, and photovoice. Three phases were analyzed based on nesting design among diverse mixed method designs. Among 134 older participants, 73 older individuals reported that their physical activity per week was less than 150min in the first phase. Among the 73 older individuals, 40 older individuals participated in the second phase. In the second phase, 32 older individuals does not meet at least 150min of moderate-to-vigorous physical activity(MVPA) suggested by DHHS. Finally, 6 older adults participated in the third phase. Five major themes emerged including 1) lack of proper information and service regarding physical activity, 2)lack of support from people close to them, 3)some limits due to chronic disease, 4)lack of appropriate facility, and 5)lack of opportunity due to existing inactive lifestyle. Based on these five themes, this study attempted to provide the improvement plans with socio-ecological model.

• Journal of Family Resource Management and Policy Review
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• v.27 no.2
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• pp.1-17
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• 2023

This study examined the relationship between family-friendly community characteristics and the life satisfaction of working mothers with elementary school children, and investigated whether the relationship was mediated by work-family conflict and facilitation of working mothers. For the analysis, the study used the response data of 627 working mothers from the 11th wave of the Panel Study on Korean Children (PSKC, 2019) and multi-mediation effect analyses were conducted using PROCESS. The main results are as follows. First, the higher neighbor support, the higher the work-family facilitation, which significantly increased life satisfaction. Second, the appropriateness of parenting environment and community service infrastructure satisfaction showed significant indirect effects with life satisfaction through increasing work-family facilitation and lowering work-family conflict. Moreover, the appropriateness of parenting environment was positively related with life satisfaction and it was a only variable that was directly associated with life satisfaction. On the other hand, the convenient access to community service infrastructure was found to lower work-family facilitation and lower life satisfaction, confirming the need for follow-up studies. This study shows that the family-friendly characteristics of the community are important for working mothers with elementary school-age children and provides empirical evidence to improve the family-friendly community characteristics.

• The Mathematical Education
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• v.62 no.1
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• pp.57-78
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• 2023

Students' engagement in lessons not only determines the direction and result of the lessons, but also affects academic achievement and continuity of follow-up learning. In order to provide implications related to teaching strategies for encouraging students' engagement in elementary mathematics lessons, this study implemented lessons for middle-low achieving fifth graders using open-ended tasks and analyzed characteristics of students' engagement in the light of the framework descripors developed based on previous research. As a result of the analysis, the students showed behavioral engagement in voluntarily answering teacher's questions or enduring difficulties and performing tasks until the end, emotional engagement in actively expressing their pleasure by clapping, standing up and the feelings with regard to the topics of lessons and the tasks, cognitive engagement in using real-life examples or their prior knowledge to solve the tasks, and social engagement in helping friends, telling their ideas to others and asking for friends' opinions to create collaborative ideas. This result suggested that lessons using open-ended tasks could encourage elementary students' engagement. In addition, this research presented the potential significance of teacher's support and positive feedback to students' responses, teaching methods of group activities and discussions, strategies of presenting tasks such as the board game while implementing the lessons using open-ended tasks.

• 한국노년학
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• v.30 no.3
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• pp.815-830
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• 2010

This study is a nonequivalent control group pretest-posttest study to determine the effects of a make up program on the self-esteem and anxiety of the elderly female dementia patients. This research was done between April 13th and May 1st, 2009. The subjects were 41 dementia patients in an elderly hospital in Honam Area. Twenty dementia patients in the experimental group got the make up measures during the two week experimental period and twenty one dementia patients in the contrast group didn't get any measure during the two week period. Make up measures were given to the experimental group 10 times for the two week period. This study used the self-esteemscale which was developed by Rosenberg(1965) and was translated and modified by Jeon Pyung Je(1974) into Korean. The anxiety status scale which this study used was developed by Spielberger(1970) and was translated and modified by Kim Jeong Taek(1991) into Korean. Collected data were analyzed with SPSS Win 12.0. T-test and multivariate analysis were done to test the hypothesis. This study also used a method of observation. The results of this study are following. After the two week make up measures, the experimental group had more self esteem and less anxiety status than the contrast group. The differences were statistically significant. The result of the observation also supported the research hypothesis. Based on this result, we suggest the make up program as an appropriate and useful nursing care intervention program for female dementia patients.

• 한국노년학
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• v.29 no.3
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• pp.805-822
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• 2009

This study aims to investigate the mental health level of the elderly people living alone and examine the difference in mental health level by socio-demographic factors and analyze the factors impacting on mental health level. The study subjects were 131 elderly people living alone who lived in "G" city. Symptom Check List-90-Revision(SCL-90-R) was used to measure mental health level. The results of this study were as follows. First, the study subjects' mental health level(3.53, 5 rating scale) was very severe and this means the mental health level of elderly people living alone is more severe than the mental health level of general elderly people. The study subjects showed depression symptom most seriously and also had severe somatization symptom. Second, there was significant difference in mental health level by gender and education level among socio-demographic factors. Third, in the final regression model, statistically significant factors impacting on the mental health level of the elderly people living alone were life satisfaction, ADL, IADL, welfare service support, informal support, contact frequency with children, duration of living alone, subjective state of economy. And comprehensive(macro and micro) implications were recommended.

• 한국노년학
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• v.30 no.3
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• pp.695-708
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• 2010

Purpose: This study was to explore the factors affecting on Dietary Behavior Change of the vulnerable elderly based on the Stage of Change. Methods: This study was a secondary analysis of the data collected from 1,262 elderly who were participated in the case management program. Total 984 participants who responded all questionnaire were included in the analysis. The variables included general characteristics, health behavior, health status, and dietary behavior stage. The data collected were analyzed by descriptive statistics, trend test and multi-variate logistic regressions. Results: about twenty four percent of the vulnerable elderly subject was pre-contemplation stage and 46.1% of them was contemplation stage of dietary behavior. Having a depressive mood, dependance of Instrumental Activity of Daily living, and being medicaid affected on starting or on maintaining healthy dietary behavior in vulnerable elderly negatively. Conclusion: The tailored nutritional intervention depending on dietary behavior stage are needed for the vulnerable elderly to improve the health. The program which can maintain the function remained of elderly and give psychological support together will be more effective.