• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.479-494
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• 2020

The purpose of this study is to systematically analyze through structural relationship analysis the relationship between excessive smartphone use by adolescents and school adaption. A questionnaire was administered to 866 elementary, middle and high school students who are using smartphones SEM was applied to the analysis with the following results. First, the relationship between excessive smartphone use and school adaptation was not significant. Second, the relationship between social support and excessive smartphone use had significant influence. Third, there is a significant influence in the relationship between self-control and excessive smartphone use. Fourth, social support and self-control of adolescents had a direct influence on school adaptation. Fifth, social support and self-control mediate the relationship between smartphone overuse and school adaptation. Therefore, increasing the adaptability of adolescents requires efforts to firm social support system by expanding autonomous sense or self-control personally and mutual support in the family.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.5
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• pp.543-561
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• 2020

This paper is the result of the study on the effect of the support structure of the tunnel steel rib. In tunnel excavation, the top and bottom half excavation methods result in subsidence of steel rib reinforcement due to insufficient support of steel rib reinforcement when the ground is poor after excavation. The foundation of the steel rib installed in the upper half excavates the bottom part of the base, causing the subsidence to occur due to various effects such as internal load and lateral pressure. As a result, the tunnel is difficult to maintain and its safety is problematic. To solve these problems, steel rib support structures have been developed. For the purpose of verification, the behavior of the supporting structure is verified by model experiments reduced to shotcrete and steel rib material similarity, the numerical analysis of ΔP and ΔP generated by bottom excavation by Terzaghi theoretical equation. As a result, it was found that the support structure of 20.100~198.423 kN is required for the 10~40 m section of the depth for each soil of weathered soil~soft rock. In addition, as a result of the reduced model experiment, a fixed level of 50% steel rib deposit of steel rib support structure was installed. The study shows that the installation of steel rib support structures will compensate for uncertainties and various problems during construction. It is also thought that the installation of steel rib support structure will have many effects such as stability, economy, and air reduction.

• Journal of the Korean GEO-environmental Society
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• v.7 no.5
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• pp.67-77
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• 2006

Bearing capacity of soil can be improved by several conventional ground improvement techniques like stabilization and compaction. Recently, the necessity on the reseaches for the bearing capacity of footing reinforced by Geotextile is being significantly increased. In this paper, a series of model tests on sandy ground reinforced by a layer of Geotextile were performed under plane strain condition, and the effects of bearing capacity improvement and behaviour of sandy ground were observed through tests for position and horizontal length, material strength of reinforcement.

• Land and Housing Review
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• v.2 no.1
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• pp.79-85
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• 2011

The bearing capacity of a soil can be improved by conventional ground improvement techniques such as stabilization and compaction methods. Recently, the use of geotextiles in improving the bearing capacity of soils has become popular because of the availability of durable and strong geosynthetic materials. In this paper, through the laboratory model tests on sandy ground reinforced by geotextiles with the strip footing under plane strain condition, the effects of bearing capacity improvement on the sandy ground and its behaviour were investigated.

• Journal of the Korean Geotechnical Society
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• v.35 no.11
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• pp.25-36
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• 2019

The safety barrier is installed on road embankment to prevent vehicles from falling into road side slope. Among the safety barrier, flexible guardrails are usually installed. The flexible guardrail generally consists of a protection cross-beam and supporting in-line piles. These guardrail piles are installed nearby slope edge of road embankment because the side area of the road is much narrow. The protection cross-beam absorbs impact energy caused by vehicle collision. The pile-soil interaction also absorbs the rest of the impact energy and then, finally, the flexible guardrail system resists the impact load. This paper aims to investigate the pile-soil interaction subjected to impact load using centrifuge model tests. In this study, a single pile was installed in compacted residual soil and loaded under lateral impact load. An impact loading system was designed and developed available on centrifuge tests. Using this loading system, a parametric study was performed and the parameters include types of loading and ground. Finally, the ultimate bearing capacity of supporting pile under impact load was analyzed using load-displacement curve and soil reaction pressure distributions at ultimate were evaluated and compared with previous studies.

• The Journal of the Korea Contents Association
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• v.13 no.11
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• pp.423-432
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• 2013

It is very important to prevent and management negative sides in advance can occur in service transaction as an employee' attitude during service encounter has a decisive effect on customers' service evaluation. Work stress has become one of the most widely studied topics in research, mainly because of its importance to employees' psychological health, which in turn affects service quality and organizational effectiveness. This study aims to explore how social support that hotel employees perceive influence on job stress and job burnout. Data were collected from 355 hotel employees at Deluxe Hotel in Seoul, analyzed using structural equation modeling techniques. The findings are as follows Firstly, social support had a significant influence on job stress. Secondly, social support had a significant influence on job burnout. Thirdly, job stress had a significant influence on job burnout. To reduce job stress and job burnout recognition, self-esteem and motivation, the hotel need to deliver a stronger coaching program. In addition, for an organization to respond flexibly. Finally, the results were discussed in the context of providing the job burnout management for employee.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.3
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• pp.283-293
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• 2008

A study of interactive ground behaviour due to tunnelling adjacent to existing piles has not been recognized well for the most geotechnical engineers so far. Because this is a very sophisticated boundary condition problem. In this study, therefore, the author has conducted both the laboratory model test and finite element analysis (FEA) to figure out such a complicated ground behaviour related to shear strain formations. Based on the model testing and FEA results, a boundary line which divides into two distinctive shear strain formations in relation to the locations of end-bearing pile tips was proposed. The author believes that the proposed boundary line may be helpful for planning the appropriate tunnel positions for avoiding damage of buildings which supported by piled-foundations in urban areas.

• Journal of the Korean Geosynthetics Society
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• v.17 no.1
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• pp.85-93
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• 2018

A existing standard design section of transitional zone between bridge and earthwork section in high speed railway should be designed to gradually change support stiffness from bridge abutment to backfill side that were placed on cemented stabilized gravel, general gravel, soil materials. The larger the backfill slope of the general gravel and soil was more structurally stable, but there is no clear reason about them. In this study, it was compared with settlement and bearing capacity of backfill area in currently design and alternating backfill slope section using large centrifuge tester. As the experimental results, it was showed that the 1:2 slope and 1:1.5 slope have almost similar bearing capacity behavior under the load stage as railway loading level.

• Geotechnical Engineering
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• v.11 no.4
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• pp.75-86
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• 1995

After open -ended model pipe pile, which was composed of inner tube and outer tube was driven by different installation methods, degradation in open -ended pipe pile capacity was studied during simulated horizontal seismic shaking, which was modeled by records of actual earthquake. Drgradation in ultimate capacity of open -ended pipe pile during simulated earthquake was about 20% in impact pile and was approached up to about 40% in vibratal pile. Most of degradation in ultimate pile capacity was occured in the outer shaft surface and degradations in outer skin friction, toe resistance of steel, and plugging force were about 80%, 10%, 10%, respectively. out of ultimate pile capacity. It appeared that this trend did not depend upon the different installation methods of pile.

• Journal of the Korean Applied Science and Technology
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• v.38 no.3
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• pp.708-719
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• 2021

The purpose of this study was to investigate the effect of the major satisfaction and parents' career support on the behavior of career preparation among university students and to presents basic data for making active the behavior of career preparation. A survey was held to the university students in Seoul and Chungcheong cities from April 15 to May 14, 2021 195 copies were in the final analysis for data analysis, t-test, ANOVA, Pearson's Correlation Coefficient and Multiple regression was used. As a result, the factors of affecting on the behavior of career preparation were followed by Economic level, Major category, Motivation of the major, Grade, the major satisfaction and parents' career support. The multiple regression explanatory power was 50.5percent of the total changes in the behavior of career preparation. Therefore, this study could be used as a basic data for the development of education programs through increase the major satisfacton and enhance parents career support in order to the active behavior of career preparation.