• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.189-198
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• 2008

Lots of roadway tunnel have been almost constructed in forms of closely-spaced tunnel in korea. If closely-spaced tunnel is not constructed at a sufficient distance between tunnels, the problem of stability can occur. However, the case that can not secure a sufficient distance between tunnels can occur due to a difficulty in buying a lot and an issue of popular complaint and environmental disruption. Generally, tunnels are not influenced by each other when a center distance between tunnels is two times longer than tunnel diameter under the complete elastic ground and five times under the soft ground. In this study, the scaled model tests of closely-spaced tunnel by using homogeneous material were performed and induced displacements were measured around the tunnel openings during excavation. The influence of distance between tunnels on the behavior of closely-spaced tunnel was investigated.

• The Journal of Korean Association of Computer Education
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• v.11 no.6
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• pp.85-94
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• 2008

This study is to find strategies to promote distance learning effectiveness in the online learning environment. The research showed that the level of learner's perception of the structure of transactional distance was not significantly different according to sex (p>.05). There was significant correlation between the level of learner's perception of the structure and academic satisfaction(p<.01). And, the level of learner's perception of the structure and learning durability appeared to have statistically significant correlation. However there was no significant difference(p>.05) between academic achievement. Among the three subordinate factors, the course interaction organization had the most influence on the learner's academic satisfaction and the learner's learning durability was influenced the most by the content organization.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.5
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• pp.95-103
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• 2013

Protection of the electrical and electronic equipment against surges in low voltage AC power distribution systems is based on wide applications of surge protective devices(SPDs). Cascade application of SPDs located at the service entrance of a building and near sensitive equipment is intended to ensure the optimal voltage protection level and energy sharing among cascade SPDs. In this paper, when surges impinge at the service entrance of the building of interest, the protection characteristics of two-stage cascade SPD systems were investigated. The influence of the distance between the upstream and downstream SPDs on the voltage protection level and energy sharing of the two-stage cascade SPD systems were analyzed experimentally. It was found that the energy sharing of two-stage cascade SPD systems strongly depends on the distance between the two SPDs and the component of SPD. As the distance between the two SPDs increases, the energy absorbed by the upstream SPD increases while the energy absorbed by the downstream SPD decreases. Consequently, it is desirable to select the upstream and downstream SPDs having the proper energy capability with due consideration of the distance between the two SPDs.

• Journal of Environmental Health Sciences
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• v.34 no.4
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• pp.311-315
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• 2008

This study was performed to investigate propagation characteristics and effects of road traffic noise generated from vehicles. Noise levels of expressway and general road were measured at four points in a straight line based on distance from the road, and analyzed. The average noise level of expressway was 78.9 dBA at 5 m, 76.4 dBA at 10 m, 72.0 dBA at 20 m, 69.0 dBA at 30 m. That of general road was lower about $3.1{\sim}3.5\;dBA$ than that of expressway. There was no significant difference in distance attenuation between expressway noise and general road noise. The farer the distance from source is, the more the attenuation is. The influence range of noise is assessed by noise environmental standards or road noise limits. Noise levels of the time zone were measured at a boundary line of apartment to grasp noise variation by time. The time zone of lowest noises was $3{\sim}4$ a.m. and that of highest noise was $8{\sim}10$ a.m. Data recorded on tapes were analyzed to understand the characteristics of frequency because these characteristics are important factors to plan the noise reduction measures, namely path measures.

• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.91-96
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• 2014

This research deals with the combustion experiment of pine trees, which are the most representative species in Korea. Experimental data are compared with theoretical ones using Fire Simulation Program(FDS). It is considered that horizontal/vertical temperature distribution and radiant heat influence on adjacent areas in fire scenes. The linear function for separation distance to temperature was drawn by applying Stefan-Boltzmann's law; $y=112.13133{\times}({\sigma}T^4)^{-0.52916}$ for calculating the separation distance. In combustion experiment, the radiant heat came to $1.4{\sim}1.5kW/m^2$ in case of the separation distance by one meter. The numerical values mean that human body show the critical level of pain after one minute without a protective equipment.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.12
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• pp.1021-1030
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• 2016

The runner system of the injection mould and the injection volume of the injection molding process greatly affect the quality of the produced part. The goal of this paper is the design of the runner system and the prediction of the injection volume for the injection moulding of a housing part of small-size air cleaner to improve the formability through the three-dimensional injection moulding analysis. The effects of the runner system of the mould on the injection moulding characteristics are investigated. From the results of the investigation, a proper design of the runner system with uniform filling characteristics and the minimized defect formation is obtained. In addition, the influence of the moving distance of the screw on filling characteristics, weldline formation and deformation characteristics is examined. From the results of the examination, an appropriate moving distance of the screw for the housing part of small-size air cleaner is estimated.

• International Journal of Clinical Preventive Dentistry
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• v.14 no.4
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• pp.247-255
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• 2018

Objective: Osseointegration is essential process for successful implants and effects to implant in long term, therefore, passive fitness of good prosthesis is necessary. To make a good prosthesis, at first it should be done a sectioned casting and then joined method of sectioned casting body is recommended. Methods: In this study, to provide the fundamental data on stable connection method for successful implants, the author tested fitness of casting body, and compared difference between gas soldering technique and laser welding technique. Results: In fitness test of 2 abutment (test A, C), gas soldering group's fitness in the opposite part of connection was worse than laser welding group. In fitness test of 3 abutment (test B, D), gap distance was increased both in gas soldering technique and laser welding technique. Gap distance at the connecting part and the opposite part of the abutment in gas soldering technique was worse than laser welding technique and the more additional abutment, the worse gap distance in gas soldering technique. In fitness test of 3 abutment (test B, D), there's little variation in No. 2 abutment when connecting soldering process was done and there's little influence on already soldered connection part when the additional soldering connection was done. Conclusion: On weak loading condition and the part which is needed an accuracy, laser welding technique is more effective and on long-span prosthesis and frequent chewing loading part, laser welding technique is recommended first and applying additional gas soldering technique would be better for making much more successful prosthesis.

• East Asian Journal of Business Economics (EAJBE)
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• v.9 no.2
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• pp.21-30
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• 2021

Purpose -The purpose of this paper is to advance the understanding of affective commitment in employees of Korean companies' subsidiaries in Mexico. Specifically, we study the moderating effects of cultural orientation on the relationship between perceived corporate social responsibility (CSR) and affective commitment among these Mexican employees. Research design and methodology - This study was designed to explore the impact of perceived CSR on affective commitment and the moderating roles of collectivism and power distance on the employer-employee relationship. We applied hierarchical regression to survey data collected from 296 employees working for Korean company subsidiaries in Mexico to examine the proposed hypotheses. Results - The results show a significant positive effect from perceived CSR on affective commitment. In addition, this study confirms a positive moderating effect from collectivism and a negative moderating impact from power distance on the relationship between perceived CSR and affective commitment. Conclusions - Drawing upon social identity theory, this study found that Mexican employees' perceptions of their company's CSR and their own cultural value orientations influence affective commitment to the organization. This study extends the understanding of perceived CSR and affective commitment, and particularly demonstrates that the relationship between perceived CSR and affective commitment is influenced by employee collectivistic and power distance orientation.

• Journal of Korea Trade
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• v.25 no.1
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• pp.133-151
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• 2021

Purpose - This study examines the effects of expatriate transfer on foreign affiliate's labor productivity. Design/methodology - Using Korean-owned foreign affiliate-level data, we estimate the effect of expatriate transfer on foreign affiliate's labor productivity using the system generalized method of moments model. We also consider foreign affiliate- and host country-specific contingencies and test how they are associated with expatriates in enhancing foreign affiliate's labor productivity. Findings - We consider foreign production intensity and cultural distance between the home (i.e., South Korea) and host countries as key contingencies that influence the effect of expatriates on foreign affiliate's labor productivity. We find that expatriates are effective in enhancing the labor productivity of less production-intensive foreign affiliates. This effect is strengthened as expatriates are deployed to countries that share cultural similarities with the home country. Originality/value - Considering that previous studies provide mixed results on the effect of expatriates, our findings suggest that foreign affiliate-specific operational orientation and cultural distance should be considered jointly to understand the true effect of expatriate staffing on foreign affiliate performance.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.5
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• pp.571-577
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• 2008

Introduction: Possible etiologic factors associated with bone loss around implants after implantation are surgical trauma, occlusal overload, periimplantitis, presence of micro gap and the formation of biologic distances. Tarnow et al. observed that the crestal bone loss was greater when the distance between the implants was <3mm than when the implants were ${\geq}\;3mm$ apart. The aim of this study was to evaluate the influence of different interimplant distance on marginal bone and crestal bone resorption in the beagle dogs. Materials and methods: The mandibular premolars of 5 dogs were extracted bilaterally. After 12 weeks of healing, each dog received 7 implants. On each side, implants were separated by 2mm (Group 1) and by 5mm (Group 2). After 16 weeks of healing, the dogs were sacrificed. Marginal bone loss was determined through linear measurements made between the implant-abutment junctions and the most coronal portions of the bone in contact with the implant surface. A line was drawn uniting the implant-abutment junctions of the adjacent implants, and a linear measurement was made at the midpoint in the direction of the most coronal peak of the interimplant bone crest to determine the crestal bone loss. Both of them was measured radiologically and histologically. Result and conclusion: In radiological analysis, the mean of marginal bone loss was $1.26{\pm}0.14mm$ for group 1 and $1.23{\pm}0.34mm$ for group 2, the mean of crestal bone loss was $1.10{\pm}0.14mm$ for group 1 and $1.02{\pm}0.30mm$ for group 2. The results were not statistically significant between 2 groups. In histological analysis, the mean of marginal bone loss was $1.63{\pm}0.48mm$ for group 1 and $1.62{\pm}0.50mm$ for group 2, the mean of crestal bone loss was $1.23{\pm}0.35mm$ for group 1 and $1.15{\pm}0.39mm$ for group 2. The differences were also not statistically significant. The clinical significance of this result is that the increase in the crestal bone loss results in the increase in the distance between the base of the interproximal contact of the crowns and the bone crest, and this determines if papilla will be present or absent between implants. Considering this fact, keeping up sufficient interimplant distance is important to minimize crestal bone loss.