• Steel and Composite Structures
• /
• v.48 no.2
• /
• pp.207-233
• /
• 2023

Steel-concrete composite box girder bridges are widely used in the construction of highway and railway bridges both domestically and abroad due to their advantages of being light weight and having a large spanning ability and very large torsional rigidity. Composite box girder bridges exhibit the effects of shear lag, restrained torsion, distortion and interface bidirectional slip under various loads during operation. As one of the most commonly used calculation tools in bridge engineering analysis, one-dimensional models offer the advantages of high calculation efficiency and strong stability. Currently, research on the one-dimensional model of composite beams mainly focuses on simulating interface longitudinal slip and the shear lag effect. There are relatively few studies on the one-dimensional model which can consider the effects of restrained torsion, distortion and interface transverse slip. Additionally, there are few studies on vehicle-bridge integrated systems where a one-dimensional model is used as a tool that only considers the calculations of natural frequency, mode and moving load conditions to study the dynamic response of composite beams. Some scholars have established a dynamic analysis model of a coupled composite beam bridge-train system, but where the composite beam is only simulated using a Euler beam or Timoshenko beam. As a result, it is impossible to comprehensively consider multiple complex force effects, such as shear lag, restrained torsion, distortion and interface bidirectional slip of composite beams. In this paper, a 27 DOF vehicle rigid body model is used to simulate train operation. A two-node 26 DOF finite beam element with composed box beams considering the effects of shear lag, restrained torsion, distortion and interface bidirectional slip is proposed. The dynamic analysis model of the coupled composite box girder bridge-train system is constructed based on the wheel-rail contact relationship of vertical close-fitting and lateral linear creeping slip. Furthermore, the accuracy of the dynamic analysis model is verified via the measured dynamic response data of a practical composite box girder bridge. Finally, the dynamic analysis model is applied in order to study the influence of various mechanical effects on the dynamic performance of the vehicle-bridge system.

• 한국노년학
• /
• v.29 no.3
• /
• pp.1063-1085
• /
• 2009

The purposes of this study were to investigate the transition of elderly's welfare service utilization and to examine the factors affecting their utilization as time passed. To solve these research questions, the behavioral model presented by Andersen and Newman(1973) was applied. Using Hallym Aging Panel data consisted of 3 waves from 2003 to 2007, autoregressive modeling and regression analysis were applied for research purposes. The results of this study were as follows; (1) The experiences of welfare service utilization were increasing gradually. The complimentary service for the aged was utilized generally, but leisure service and community service were not used in common. (2) Past experience of service affected service utilization in the following times. (3) The factors affecting older adult's service utilization were different among the types of services. Nonetheless, the factors affecting continuously during the periods were found: age as predisposing factor and area as enabling factor in the complimentary service; area and existence of spouse as enabling factor in leisure service; education as predisposing factor and service cognition as enabling factor in community service. Enabling factor has affected more consistently than other factors. The results showed that special attention should be paid to balanced regional arrangement for welfare resources and the public relation considering the elderly's intellectual level.

• 한국노년학
• /
• v.29 no.3
• /
• pp.971-986
• /
• 2009

This research investigated how the participation of various social activities affects cognitive function in middle-aged and elderly population. To examine the relation between the participation of various social activities and cognitive function, we used data from the Korean Longitudinal Study of Ageing. Social activities were classified into four types as religious ritual, leisure, public association and ascriptive association activities, and MMSE-K score was used to measure cognitive function. Results from multiple regression analyses after adjusting for socio-economic status and health status show that the participation in religious and leisure activities have positive effects on cognitive function in middle-aged and elderly population. Participation in leisure activities in middle-aged male group helps preserve cognitive function, and leisure activity and ritual activity are significantly related to cognitive function in middle-aged female group. Meanwhile the participation in religious and leisure activities have positive effects on cognitive function in elderly male and female group. Based on these findings, we suggest that various programs to support the participation of elderly population in social activities should be developed for healthy life for the elderly.

• 한국노년학
• /
• v.31 no.2
• /
• pp.195-209
• /
• 2011

This study examined the prevalence of and factors associated with unmet care need among community-dwelling middle-aged and older people in Korea. Data were from the 2006 Korean Longitudinal Study on Ageing (KLoSA), a national survey of 10,254 non-institutionalized adults aged 45 or older. Having unmet care needs was defined as needing personal assistance with activities of daily living (ADL) or instrumental activities of daily living (IADL) but having no available helper. Weighted logistic regressions were fitted to examine factors associated with unmet care needs. Overall, 7.3%, 14.5%, and 41.8% of subjects among the middle-aged, younger old, and older old, respectively, reported care needs of these, 34%, 33%,and 24% had unmet needs. Factors associated with unmet needs differed among the three groups: Education and income level were negatively associated with unmet needs among the middle-aged, but living alone was the only factor positively associated with unmet needs in both the younger and older old. The prevalence of and factors associated with unmet care needs differ by life-stage. Needed are home- and community-based care and services to meet the need for personal assistance among the elderly living alone in a community.

• 한국노년학
• /
• v.27 no.2
• /
• pp.393-408
• /
• 2007

This study examines the impact of retirement on psychological well-being of the elderly and identifies whether associative factors of psychological well-being differ between retired and non-retired persons. Psychological well-being is measured by the PGCMS developed by Lawton. The sample includes 1,625 older adults aged 60 and over, which derived from the cross-sectional data of the "Aging and the Quality of Life of the Elderly in Korea: A Longitudinal Study" living in Seoul and Chuncheon in 2003. Multivariate OLS regression results show that retirement is not associated with psychological well-being after controlling socio-demographic characteristics, economic status, health status, family and social relations, participation in social activities, and satisfaction with hobbies and learning needs. Also, associative factors of psychological well-being differ between retired and non-retired persons. For retired persons, greater social activities and higher satisfaction with hobbies are associated with the higher level of psychological well-being whereas higher satisfaction with learning needs has a positive relationship with the higher level of psychological well-being for non-retired persons. Discussion and implications of the findings are presented, and limitations of this study are acknowledged.

• 한국노년학
• /
• v.31 no.3
• /
• pp.463-478
• /
• 2011

This study examined the impact of late-life poverty on self-rated health, focusing on the mediating and moderating effects of health behaviors and social support. Despite the significant associations among poverty, health behaviors, and health outcomes, little studies have tested complex structural pathways among them. Thus, the purpose of this study is to identify multiple causal pathways between poverty and self-rated health, mediated and moderated by health behaviors and social support. To test the structural pathways, the structural equation modeling was utilized using the 2006 Korean Longitudinal Study of Aging data. The results of this study indicated that poverty had the direct negative impact not only on the health behaviors such as smoking and lack of regular exercise but also on the self-rated health. In addition, regular exercise significantly mediated the relationship between poverty and self-rated health. Finally, informal social support from family and friends buffered the negative impact of poverty on the self-rated health. Findings suggested that providing informal social support to the low income elderly is important in addition to the economic support. It is also necessary to develop programs for promoting healthy behaviors, especially regular exercise.

• 한국노년학
• /
• v.39 no.1
• /
• pp.93-108
• /
• 2019

The purpose of this study is to examine the effect of absolute / relative poverty on the life satisfaction focusing on mediation effect of subjective social status by type of elderly residents. In order to analyze the distinct characteristics of the elderly, analysis was conducted with 3,327 the elderly living together and 668 the elderly living alone using 'Korean Longitudinal Study of Ageing(KLoSA)' from 3rd to 5th wave data provided by the Korea Employment Information Service. The main analysis results are as follows. First, each poverty rate for the elderly living together accounted for 43.5 percent and 51.4 percent, while 63.8 percent and 77.2 percent for the elderly living alone respectively. Second, life satisfaction was higher among the elderly living together than living alone, However, life satisfaction was not related to condition of poverty among the elderly living alone. Third, absolute / relative poverty were associated with life satisfaction of the elderly living together, and subjective social status had a mediating effect. However, relative poverty was not related to life satisfaction among the elderly living alone, which indicated that it needs to support not only the financial approach to overcome absolute poverty but also the multi-dimensional poverty perspective in the intervention of the elderly living alone Based on the results, the study suggested to make a tool to measure of poverty using multi-dimensional poverty indicators.

• Asia Marketing Journal
• /
• v.15 no.3
• /
• pp.53-77
• /
• 2013

As advertising and promotions are categorized as operating expenses, managers tend to reduce marketing budget to improve their short term profitability. Gauging the value and accountability of marketing spending is therefore considered as a major research priority in marketing. To respond this call, recent studies have documented that financial market reacts positively to a firm's marketing activity or marketing related outcomes such as brand equity and customer satisfaction. However, prior studies focus on the relation of marketing variable and financial market variables. This study suggests a channel about how marketing activity increases firm valuation. Specifically, we propose that a firm's marketing activity increases the level of the firm's product market information and thereby the dispersion in financial analysts' earnings forecasts decreases. With less uncertainty about the firm's future prospect, the firm's managers and shareholders have less information asymmetry, which reduces the firm's cost of capital and thereby increases the valuation of the firm. To our knowledge, this is the first paper to examine how informational benefits can mediate the effect of marketing activity on firm value. To test whether marketing activity contributes to increase in firm value by mitigating information asymmetry, this study employs a longitudinal data which contains 12,824 firm-year observations with 2,337 distinct firms from 1981 to 2006. Firm value is measured by Tobin's Q and one-year-ahead buy-and-hold abnormal return (BHAR). Following prior literature, dispersion in analysts' earnings forecasts is used as a proxy for the information gap between management and shareholders. For model specification, to identify mediating effect, the three-step regression approach is adopted. All models are estimated using Markov chain Monte Carlo (MCMC) methods to test the statistical significance of the mediating effect. The analysis shows that marketing intensity has a significant negative relationship with dispersion in analysts' earnings forecasts. After including the mediator variable about analyst dispersion, the effect of marketing intensity on firm value drops from 1.199 (p < .01) to 1.130 (p < .01) in Tobin's Q model and the same effect drops from .192 (p < .01) to .188 (p < .01) in BHAR model. The results suggest that analysts' forecast dispersion partially accounts for the positive effect of marketing on firm valuation. Additionally, the same analysis was conducted with an alternative dependent variable (forecast accuracy) and a marketing metric (advertising intensity). The analysis supports the robustness of the main results. In sum, the results provide empirical evidence that marketing activity can increase shareholder value by mitigating problem of information asymmetry in the capital market. The findings have important implications for managers. First, managers should be cognizant of the role of marketing activity in providing information to the financial market as well as to the consumer market. Thus, managers should take into account investors' reaction when they design marketing communication messages for reducing the cost of capital. Second, this study shows a channel on how marketing creates shareholder value and highlights the accountability of marketing. In addition to the direct impact of marketing on firm value, an indirect channel by reducing information asymmetry should be considered. Potentially, marketing managers can justify their spending from the perspective of increasing long-term shareholder value.

• Korean Journal of Culture and Social Issue
• /
• v.16 no.4
• /
• pp.447-468
• /
• 2010

The purpose of this study was to attain a clearer understanding of the reciprocal effects of deviant self-concept and delinquent behaviors by applying a latent state-trait autoregressive modeling approach. Although traditional autoregressive cross-lagged (ARCL) modeling has been widely applied to test the longitudinal reciprocal relationship between the two constructs, it could produce misspecified findings if there were trait-like processes involved in this relationship. The latent state-trait autoregressive(LST-AR) modeling was applied to control trait effects of deviant self-concept and to examine the reciprocal causal relations between the two constructs. Data were taken from a sample of 3,449 eighth graders who were followed annually for 5 years from the Korea Youth Panel Study. The combining LST-AR model with ARCL model substantiated the reciprocal effects of deviant self-concept and delinquent behaviors, even after the stable trait component of deviant self-concept was taken into account. The present findings shed lights on the reciprocal effects of behaviors (i.e., delinquency) and self concepts (i.e., deviant self-concept). Not only did behaviors change corresponding self-concept, but the ways adolescents perceived themselves influenced their behaviors.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.26 no.2
• /
• pp.113-128
• /
• 2024

Items of road tunnel PISD (Precise Inspection for Safety and Diagnosis) were reviewed and analyzed using newly enhanced MMS (Mobile Mapping System) technology. Possible items with MMS can be visual inspection, survey and non-destructive test, structural analysis, and maintenance plan. The resolution of 3D point cloud decreased when the vehicle speed of MMS is too fast while the calibration error increased when it is too slow. The speed measurement of 50 km/h is determined to be effective in this study. Although image resolution by MMS has a limit to evaluating the width of crack with high precision, it can be used as data to identify the status of facilities in the tunnel and determine whether they meet disaster prevention management code of tunnel. 3D point cloud with MMS can be applicable for matching of cross-section and also possible for the variation of longitudinal survey, which can intuitively check vehicle clearance throughout the road tunnel. Compared with the measurement of current PISD, number of test and location of survey is randomly sampled, the continuous measurement with MMS for environment condition can be effective and meaningful for precise estimation in various analysis.