• Journal of the Korean Society of Safety
• /
• v.31 no.6
• /
• pp.45-51
• /
• 2016

The purpose of this study is to investigate the influence of train-induced end rotation of simple supported track girder on the performance of a direct fixation track system (DFTS) in Yeongjong grand bridge. In this study, the influences of deflection of a DFTS and track girder on dynamic rail-track girder interaction forces for the track girder ends currently employed in airport express lines were assessed by performing field tests using actual vehicles running along the service lines. Therefore, the dynamic displacement of rail and track girder and the fastener stress on the center and ends sections of DFTS were measured for two different trains (AREX and KTX) running in Yeongjong grand bridge. A three-dimensional finite element analysis (FEA) model using the time-history function based on the design wheel load was used to predict the train-induced track and track girder displacement, and the FEA and field test results were compared. The analytical results reproduced the experimental results well within about 3-7% difference in the values. Therefore, the FEA model of DFTS on track girder is considered to provide sufficiently reliable FEA results in the investigation of the behavior of DFTS. Using the analytical and experimental results, the influence of train-induced end rotation of simple supported track girder on the interaction behavior of rail and track girder installed on a simple supported track girder ends, i.e., upward displacement of rail-track girder and the fastener stress, was investigated. It was found that the train-induced end rotation effect of track girder was not significantly affected by the upward displacement of rails and the fastener stresses of track girder ends. Further, the interaction behavior of rail and track girder were similar to or less than that of the general railway bridge deck ends, nevertheless the vertical displacement of track was higher than that of conventional DFTS on the general railway bridge. From the results, the dynamic responses of the DFTS on track girder ends were not significantly affected by the safety and stability of DFTS ends.

• Asia-Pacific Journal of Business
• /
• v.14 no.1
• /
• pp.93-112
• /
• 2023

Purpose - Due to the outbreak and spread of COVID-19, companies have reduced their hiring needs in the short term, reducing employment opportunities for most university students and putting pressure on their employment since 2019. This study aims to improve university students' employment options and increase the possibility of entrepreneurship. Design/methodology/approach - In this study, a research survey is conducted on 4-year Chinese university students who have received entrepreneurship education courses, and statistical tests are conducted using SPSS 26.0 and PROCESS 3.3 model 1. The main focus of the study is on the effects of risk perception and five personality factors on entrepreneurial intentions of Chinese university students and the effect of entrepreneurship education on the moderation of entrepreneurial intentions. Findings - The results of the study show that the risk perception of Chinese university students have a significant effect on the will to start a business. Five personality factors have a significant effect on entrepreneurial intentions. Entrepreneurship education has a moderating role in the relationship between risk perception and entrepreneurial intention, and the entrepreneurship education support has a moderating role in the relationship between the influence of five personality factors and entrepreneurial intentions. Research implications or Originality - The results of the study reveal that Chinese university students' exposure to entrepreneurship education support positively influenced entrepreneurial intentions. Such results imply that university students gain information and knowledge related to entrepreneurship through the entrepreneurship education support, which leads to positive perceptions and motivation towards entrepreneurship.

• Journal of Soil and Groundwater Environment
• /
• v.17 no.4
• /
• pp.44-50
• /
• 2012

A new type of chemical oxidation technology utilizing micro bubble ozone oxidizer and a pneumatic fracturing equipment was developed to enhance field applicability of a traditional chemical oxidation technology using hydrogen peroxide as an oxidizer for in-situ soil remediation. To find an efficient way to dissolve gaseous ozone into hydrogen peroxide, ozone was injected into water as micro bubble form then dissolved ozone concentration and its duration time were measured compared to those of simple aeration of gaseous ozone. As a result, dissolved ozone concentration in water increased by 31% (1.6 ppm ${\rightarrow}$ 2.1 ppm) and elapsed time for which maximum ozone concentration decreased by half lengthened from 9 min to 33 min. When the developed pneumatic fracturing technology was applied in sandy loam, cracks were developed and grown in soil for 5~30 seconds so that the radius of influence got longer by 71% from 392 cm to 671 cm. The remediation system using the micro bubble ozone oxidizer and the pneumatic fracturing equipment for field application was made and demonstrated its remediation efficiency at petroleum contaminated site. The system showed enhanced remediation capacity than the traditional chemical oxidation technology using hydrogen peroxide with reduced remediation time by about 33%.

• Journal of the Korea Convergence Society
• /
• v.11 no.3
• /
• pp.171-179
• /
• 2020

Media technologies that have made the hyper-connected age change the way people use communication text. Ads texts actively used by companies are storytelling and storydoing. These two advertising texts are very effective in inducing people's emotions and forming participatory behavior. People's thinking tendency also influence persuasion. The results of this study are as follows according to the type of ads text and the thinking tendency of consumers. Consumers' attitudes toward ads turned out to be more positive in synthetic thinking. In analytical thinking, the storytelling ads texts induced more favorable responses. On the other hand, in comprehensive thinking, the story doing text was effective. The same result was found in the perception of premium value, willingness to pay premium price, and repurchase intention.

• Journal of the Korean Society for Railway
• /
• v.16 no.1
• /
• pp.71-77
• /
• 2013

This study analyzes how deep acting and surface acting, both classified as emotional labor, influence emotional exhaustion and turnover-intention for 263 KTX attendants. The followings are the summarized results of our analysis. First, the deep acting of KTX attendants does not affect emotional exhaustion, but surface acting was found to have a positive influence on emotional exhaustion. Second, the deep acting of KTX attendants had a positive impact on turnover-intention, but surface acting did not affect turnover-intention. Last, the emotional exhaustion of KTX attendants had a positive impact on turnover-intention. In conclusion, these results imply that it is important for employers to manage their employees' emotion in order to prevent turnover among KTX attendants.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.6
• /
• pp.1083-1090
• /
• 2009

In 18GHz using unified data transmission in a subway and railway, Influence of the multipath fading is big and an arrival range of the micro wave takes the influence greatly according to the transmit angle and receive angle because it not diffracted. This thesis analyzed microwave property underground tunnel and ground railway at unified data transmission in subway and railway. Antenna gain of directional antenna many used unified transmission in an subway and railway, is used 15dBi and 10dBi in simulation. Transmitter's property is compared underground tunnel to ground railway about curved railway of R=100, R=200, R=400. Specification of transmitter is used sample unified transmission system in subway and railway of KRRI(korea railroad research Institute). Transmitter's power is 20dBm and Reciever's sensitivity is -90dBm. According to result of simulation.

• Journal of Environmental Science International
• /
• v.20 no.12
• /
• pp.1541-1551
• /
• 2011

This study applied the Bayesian method for the quantification of the parameter uncertainty of spatial linear mixed model in the estimation of the spatial distribution of probability rainfall. In the application of Bayesian method, the prior sensitivity analysis was implemented by using the priors normally selected in the existing studies which applied the Bayesian method for the puppose of assessing the influence which the selection of the priors of model parameters had on posteriors. As a result, the posteriors of parameters were differently estimated which priors were selected, and then in the case of the prior combination, F-S-E, the sizes of uncertainty intervals were minimum and the modes, means and medians of the posteriors were similar to the estimates using the existing classical methods. From the comparitive analysis between Bayesian and plug-in spatial predictions, we could find that the uncertainty of plug-in prediction could be slightly underestimated than that of Bayesian prediction.

• Steel and Composite Structures
• /
• v.21 no.2
• /
• pp.373-394
• /
• 2016

The postbuckling behavior of laminated composite plates and shells, subjected to various shear loadings, is presented, using a modified 8-ANS method. The finite element, based on a modified first-order shear deformation theory, is further improved by the combined use of assumed natural strain method. We analyze the influence of the shell element with the various location and number of enhanced membrane and shear interpolation. Using the assumed natural strain method with proper interpolation functions, the present shell element generates neither membrane nor shear locking behavior even when full integration is used in the formulation. The effects of various types of lay-ups, materials and number of layers on initial buckling and postbuckling response of the laminated composite plates and shells for various shear loading have been discussed. In addition, the effect of direction of shear load on the postbuckling behavior is studied. Numerical results and comparisons of the present results with those found in the literature for typical benchmark problems involving symmetric cross-ply laminated composites are found to be excellent and show the validity of the developed finite element model. The study is relevant to the simulation of barrels, pipes, wing surfaces, aircrafts, rockets and missile structures subjected to intense complex loading.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.17 no.6
• /
• pp.257-269
• /
• 2013

In this study, the capability of an existing analysis method for the fluid-structure-soil interaction of an offshore wind turbine is expanded to account for the geometric nonlinearity and sea water drag force. The geometric stiffness is derived to take care of the large displacement due to the deformation of the tower structure and the rotation of the footing foundation utilizing linearized stability analysis theory. Linearizing the term in Morison's equation concerning the drag force, its effects are considered. The developed analysis method is applied to the earthquake response analysis of a 5 MW offshore wind turbine. Parameters which can influence dynamic behaviors of the system are identified and their significance are examined.

• Journal of the Korean Society of Safety
• /
• v.17 no.4
• /
• pp.101-109
• /
• 2002

The electrical properties of polyethylene are changed by the superstructure. Such crystalline polymer as polyethylene or polypropylene changes crystallinity and products spherulite or trans-crystal when it is cooled slowly. In this study, after thermal treatment of LDPE at 100[${circ}C$], in silicone oil for an hour, we made specimens in order of slow cooling, water cooling, quenching according to cooling speed. Also, to study the influence of electrical properties due to the superstructure change, we analyzed physical properties and performed dielectric breakdown experiments using DC and impulse voltage Moreover we measured space charges in bulk using Laser Induced Pressure Pulse(LIPP) method. Trap level of specimen is 0.064[eV] at the low temperature region 0.31[eV] at the high temperature region in DC dielectric strength, 0.03[eV] at the low temperature region 0.0925[eV] at the high temperature region in impulse dielectric strength. As its result shows that the quantity of charges induced from the electrode surface increases with applied voltage time, and the distribution of space charges in samples increases the quantity of charges in proportion to applied voltage.