• 한국안전학회지
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• 제31권6호
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• pp.45-51
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• 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.

• 아태비즈니스연구
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• 제14권1호
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• pp.93-112
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• 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.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권4호
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• pp.44-50
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• 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%.

• 한국융합학회논문지
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• 제11권3호
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• pp.171-179
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• 2020

초 연결시대를 가능하게 한 미디어 기술은 사람들이 활용하는 커뮤니케이션 텍스트의 양상을 바꾸고 있다. 기업에서 활발하게 사용하고 있는 광고텍스트는 스토리텔링과 스토리두잉이다. 이 두 가지 광고텍스트는 사람들의 감정을 유발하고 참여행동을 형성하는데 매우 효과적이다. 사람들의 사고유형도 설득에 영향을 미친다. 광고텍스트유형과 소비자의 사고 형식에 따른 연구결과는 다음과 같다. 우선 소비자의 광고에 대한 태도의 경우는 종합적 사고유형이 분석적 사고의 틀보다 더 긍정적인 것으로 밝혀졌다. 분석적 사고에서는 스토리텔링 광고텍스트가 더 호의적인 반응을 유도하였고, 반면에 종합적 사고에서는 스토리두잉 광고텍스트가 효율적인 것으로 나타났다. 이와 같은 결과는 프리미엄 가치 지각, 프리미엄 가격 지불의향 그리고 재구매의도에서도 동일하게 나타났다.

• 한국철도학회논문집
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• 제16권1호
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• pp.71-77
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• 2013

본 연구는 KTX승무서비스 종사자 263명을 대상으로 이들이 경험하는 감정노동을 내면행동과 표면행동으로 구분하고, 각각 감정소진과 이직의도에 미치는 영향을 실증 분석 하였다. 분석결과, KTX승무서비스 종사자의 내면행동은 감정소진에 유의미한 영향을 미치지 않았으나, 표면행동은 정(+)의 영향을 미치는 것으로 나타났다. 또한 KTX 승무서비스 종사자의 내면행동은 이직의도에 부(-)의 영향을 미쳤으나, 표면행동은 유의미한 영향을 미치지 않는 것으로 나타났다. 마지막으로 KTX승무서비스 종사자의 감정소진은 이직의도에 유의미한 정의 영향을 미치는 것으로 나타났다. 결론적으로 본 연구는 KTX승무서비스 종사자의 이직예방을 위해서는 감정관리가 중요하다는 사실을 시사하고 있다.

• 한국정보통신학회논문지
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• 제13권6호
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• pp.1083-1090
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• 2009

차지상간 통합데이터전송 시스템에서 사용하는 18GHz는 다중경도페이딩의 영향이 크고, 회절이 되지 않아 전파의 도달 범위가 송신각과 수신각에 따라 크게 영향 받는다. 본 논문은 차지상간통합데이터전송 시스템에서 지하구간의 전파 특성과 지상 구간의 전파 특성을 비교하였다. 18GHz 차지상통합데이터전송 시스템에 주로 사용되는 지향성 무선안테나인 이득이 15dBi 와 10dBi인 안테나를 사용했을 경우를 가정하여 반경이 100, 200, 400인 선로에 대하여 표준적인 특성을 지상선로구간과 지하터널구간으로 나누어 비교하였다. 이때 송수신 특성은 한국철도기술연구원의 차지상간통합전송의 OFDM모뎀방식의 샘플시료의 송신 출력은 20dBm, 수신감도는 -90dBm을 사용하여 시뮬레이션하였다.

• 한국환경과학회지
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• 제20권12호
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• pp.1541-1551
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• 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
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• 제21권2호
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• pp.373-394
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• 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.

• 한국지진공학회논문집
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• 제17권6호
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• pp.257-269
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• 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.

• 한국안전학회지
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• 제17권4호
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• pp.101-109
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• 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.