• Journal of the Korean Data and Information Science Society
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• v.25 no.4
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• pp.715-725
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• 2014

This study uses a quantile regression analysis to investigate intergenerational economic mobility in Korea. The analysis is based on data from the 1st through 11th waves of the Korean Labor and Income Panel Study (KLIPS) conducted from 1998-2008. The household nature of the data allows us to link parents' incomes to children's incomes at different points in time. Using a quantile regression analysis instead of mean one reveals that the effect of fathers' earnings are different across the conditional distribution of sons' earnings, particularly being larger on the upper quantile than on the lower quantile. After controlling effect of sons' college education by including a dummy variable for the degree, however, the pattern among quantile effects for fathers' earnings is no longer clear. Instead a new pattern emerges that education has a much larger effect on the upper quantiles than on the lower ones. Using nonparametric estimates of conditional density curves based on the quantile regression results, we derive some interesting features in graphical forms, which are not obvious in numerical analysis.

• Journal of Labour Economics
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• v.40 no.3
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• pp.29-55
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• 2017

We examine the effects of the self-reported subjective and the objective health indexes on work compensations. The compensations consist of monetary factors, such as wages, and non-monetary factors reflecting job risks such as the workplace accidence. The wages and workplace injuries are clearly affected by gender and age differences as the subjective and objective health factors of elderly workers are combined with physical and systematic work environments. Mental health problems such as work depression are more serious especially for high income elderly groups. The elderly workers experienced with physical problems and chronic illnesses are led to the decrease in wages and the increase in safety accident risks at work sharply. Therefore, we need to provide supporting services, retirement planning designed by companies, supported by the government enhanced risk working conditions and the weakness on protecting jobs.

• Environmental and Resource Economics Review
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• v.14 no.2
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• pp.291-336
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• 2005

This paper investigates how oil price changes have an impact on the Korean manufacturing production activities. For this investigation, we use a structural VAR motel to estimate impulse response functions of industrial production, producer price and export price to an oil price increase over manufacturing industries. It finds that in most manufacturing industries, an oil price increase leads to decreases in industrial productions and domestic prices except energy intensive industries, but to increases in industrial export prices except non-metallic (26), computers and offic machinery (30), electronic components, radio, television and communication (32) industries. This result explains that an oil price increase makes negative impacts on the manufacturing production activities not only through demand slowdown in the domestic markets but also through supply contraction in the export markets.

• Korean Journal of Applied Biomechanics
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• v.19 no.4
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• pp.663-669
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• 2009

The purpose of this study was to investigate the functional role of foot effectiveness when humans execute running turn maneuvers. Foot rotation angle at the starting turn and body angle at the vertical axis were analyzed through three-dimensional image analysis and ground reaction force analysis. Then, we created a simple equation: foot effectiveness = total foot rotation angle/total body rotation angle at the vertical axis. This equation made it possible to explain the dynamics of angular running turns. We analyzed data from running turns(0, 30, and 60) at average initial running velocities of 4.5, as well as rotations around the vertical axis during the running turns. As a result, the stance time, foot placement, and left and right force increased.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.89-89
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• 2019

수환경으로 유출되는 유해화학물질은 독성을 가지고 직접 유출되거나 다양한 매체와 반응하여 화재 및 폭발 등의 사고가 발생한다. 실제로 낙동강 유역에서는 1991년 페놀 유출사고를 시작으로 2009년 구미공단 '1,4-다이옥산' 유출사고, 2014년 11월 경북 봉화군의 황산유출사고 등 크고 작은 사고가 빈번히 발생하고 있으며 작년 6월에는 대구와 부산의 수돗물에서 과불화화합물이 검출되기도 하였다. 이러한 대규모 사고를 방지하기 위해 신속한 오염물의 거동 예측이 가능한 추적모델이 필요하며, 본 연구에서는 수환경으로 유출된 유해화학물질의 추적을 위한 1차원 저장대 모형을 개발하였다. 일반적으로 저장대 모형은 복잡한 하천 구조를 하천의 주 흐름이 존재하는 본류대와 하천 흐름이 정체되는 저장대, 그리고 하상구조로 단순화 하여 나타낸다. 본류대에서는 하천흐름에 의한 이송 및 횡방향 유속차로 발생하는 전단류에 의한 확산이 일어나며, 저장대와의 물질교환으로 발생하는 저장효과와, 하상구조와의 흡착 및 탈착, 그리고 생물화학적 반응 및 휘발이 발생한다고 가정한다. 본류대와 저장대간의 질량교환은 난류유속변동과 농도차에 의해서만 발생한다고 가정하고 오염물질의 이송과 분산과정을 해석한다. 저장대에서는 이송 및 전단류에 의한 확산은 일어나지 않으며, 본류대와의 물질교환으로 발생하는 저장효과와 하상구조로의 흡착, 그리고 생물화학적 반응 및 휘발이 발생한다고 가정하며, 하상구조에서는 본류대 및 저장대와의 흡착 및 탈착만 발생한다고 가정한다. 저장대 모형의 해석을 위해서는 리치(Reach) 별로 본류대 분산계수($K_F$), 본류대 면적($A_F$), 저장대 면적($A_S$), 그리고 저장대 교환계수(${\alpha}$)의 네 가지 저장대 매개변수가 필요하며 본 연구에서 개발된 저장대 모형은 흡탈착, 생물화학적 반응 및 휘발 과정을 모두 고려하여 유해화학물질의 확산 거동을 모의한다. 최적의 리치길이, 흡탈착, 반응 및 휘발 계수를 산정하여 모형의 정확도를 향상시켰으며, 신속하고 정확하게 오염물의 거동을 예측할 수 있었다.

• The Journal of the Korea Contents Association
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• v.16 no.9
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• pp.308-328
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• 2016

The purpose of this study is to examine, at the team level, the relationship between shared leadership and team work engagement and team psychological capital which have rarely been introduced into academic leadership research in Korea. This study tested the impact of shared leadership on team work engagement and the mediating role of team psychological capital between the two variables. And also, this study tested moderating role of task characteristics between shared leadership and team psychological capital. A total of 421 employees of 100 teams in 16 companies in South Korea participated in this study. The SPSS 23.0 statistical program was used in this study to analyze and statistically process the collected survey data. The result showed that high level of shared leadership positively influence team work engagement and team PsyCap works as mediator in the relationship between shared leadership and team work engagement. This results means that shared leadership is a crucial factor to facilitate team's psychological capital toward team's work engagement. However, Task characteristics had no moderating effect between shared leadership and team PsyCap. Finally, theoretical and practical implications of the study results have been discussed along with limitations and future direction of the study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.188-198
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• 2021

The purpose of this study is to verify the mediating effect from acceptance of the latest 4th Industrial Revolution technologies on the relationships between interest in the latest technologies, resistance to the latest technologies, and anxiety in workers at welfare institutions for the disabled. In order to achieve this goal, data were collected from July to August 2018 from workers at disability welfare centers in P Metropolitan City, and we analyzed data from 187 persons. Multiple regression analysis was applied to test the causal relationships between variables; the step-by-step analysis model of Baron and Kenny (1986) was used to verify mediating effects, and the Sobel test was performed to verify their significance. The analyses verified that the degree of interest in the latest technologies affects the degree of resistance to, and anxiety over, the latest technologies through acceptance of the latest technologies. At the same time, we verified that the degree of interest had a complete mediation effect because it did not directly affect the acceptance. In addition, the Sobel test result showed that the mediating effect was statistically significant. In other words, it was found that the degree of interest in the latest 4th Industrial Revolution technologies from workers at welfare institutions for the disabled increases the possibility of adaptation to future society by lowering resistance and anxiety through acceptance of the latest technologies. Based on these results, a plan to reduce resistance to, and anxiety over, the latest technologies was sought, and related measures to increase interest in the latest technologies and their acceptance are suggested.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.167-174
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• 2021

The purpose of this study is to compare the perception of forest activities effects and academic stress of 3^rd and 4^th year nursing students. The data collection period is from April 15 to May 10, 2021, and the subjects of this study are nursing students, 179 third-graders students and 121 fourth-graders, totaling 300 students. Using the SPSS (ver.25) program, the collected data were analyzed as t-test for differences in forest activity effect recognition and academic stress, including the general characteristics of the subjects, and the correlation between each variable was confirmed. As a result of the study, the degree of perception of the forest activities effects was 3.89 points (out of 5 points) and the degree of academic stress was 3.41 points (out of 6 points). Comparison results by grade level, the current health status was positively perceived by the 3rd grade students, the perception of forest activities effects was higher in the 4th grade students, and the academic stress was higher in the 4th grade students. Perception of forest activities effects, grade, current health status, and appropriateness of forestry activities showed a positive correlation and an inverse correlation with academic stress. It may be concluded it will be necessary to develop practical programs that can practice forest activities to improve health and reduce academic stress.

• Journal of Korean Society of Transportation
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• v.29 no.6
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• pp.97-106
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• 2011

Mode choice model is an essential element for estimating- the demand of new means of transportation in the planning stage as well as in the establishment phase. In general, current demand analysis model developed for the mode choice analysis applies common parameters of utility function in each region which causes inaccuracy in forecasting mode choice behavior. Several critical problems from using common parameters are: a common parameter set can not reflect different distribution of coefficient for travel time and travel cost by different population. Consequently, the resulting model fails to accurately explain policy variables such as travel time and travel cost. In particular, the nonlinear logit model applied to aggregation data is vulnerable to the aggregation error. The purpose of this paper is to consider the regional characteristics by adopting the parameters fitted to each area, so as to reduce prediction errors and enhance accuracy of the resulting mode choice model. In order to estimate parameter of each area, this study used Household Travel Survey Data of Metropolitan Transportation Authority. For the verification of the model, the value of time by marginal rate of substitution is evaluated and statistical test for resulting coefficients is also carried out. In order to crosscheck the applicability and reliability of the model, changes in mode choice are analyzed when Seoul subway line 9 is newly opened and the results are compared with those from the existing model developed without considering the regional characteristics.

• Journal of Korean Society of Transportation
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• v.27 no.5
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• pp.17-28
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• 2009

There are many limitations in dealing with rapidly changing traffic demand in urban cities. Thus recently, traffic operation and management skills are more emphasized rather than the expansion of traffic facilities. In particular, in the interrupted flow formed by signalized intersections, it is quite important to give optimal signal timing to each intersection with consideration of progression. However, as fixed signal times per direction can affect passing capacity in signalized intersections, the present four-signal phase including a left-turn signal has many limitations, including reduction of directional road capacity when traffic demand is increases dramatically during peak hours. Because of this problem, lots of studies about internal metering techniques for oversaturated signal control skills have progressed but these techniques are not used widely due to the absence of detectors for queue sensing in real-time signal control systems. In this research, a new methodology called the "restrictive left-turn signal control", which is already used at the intersection above Samsung subway station, is suggested in order to reduce control delay of urban arterial roads. The restrictive left-turn signal control allows a driver to make a U-turn and then a right turn instead of turning left in that intersection. With this change, the restrictive left-turn signal control can contribute to increased intersection capacity by reducing the number of signal phases and maximizing the through phase time. However, road structure and traffic conditions at the target intersections should be considered before the adoption of the proposed signal control.