• Journal of Korean Society on Water Environment
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• v.35 no.2
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• pp.131-144
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• 2019

Climate Change affects the hydrological cycle in agricultural watersheds through rising air temperature and changing rainfall patterns. Agricultural watersheds in Korea are characterized by extensive paddy fields and intensive water use, a resource that is under stress from the changing climate. This study analyzed the effects of climate change on river flows for Geum Cheon and Eun-San Choen watershed using STREAM, a semi-distributed watershed model. In order to evaluate the performance and improve the reliability of the model, calibration and validation of the model was done for one flow observation point and three reservoir water storage ratio points. Climate change scenarios were based on RCP data provided by the Korea Meteorological Administration (KMA) and bias corrections were done using the Quantile Mapping method to minimize the uncertainties in the results produced by the climate model to the local scale. Because of water mass-balance, evapotranspiration tended to increase steadily with an increase in air temperature, while the increase in RCP 8.5 scenario resulted in higher RCP 4.5 scenario. The increase in evapotranspiration led to a decrease in the river flow, particularly the decrease in the surface runoff. In the paddy agricultural watershed, irrigation water demand is expected to increase despite an increase in rainfall owing to the high evapotranspiration rates occasioned by climate change.

• Composites Research
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• v.36 no.6
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• pp.383-387
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• 2023

Carbon fiber-reinforced composites have excellent mechanical properties. However, the fracture toughness is a disadvantage due to brittle failure mode. The fracture toughness can be enhanced using hybridization with large-elongation fibers. In this study, polyamide (aramid) fibers are hybridized with carbon fiber with various stacking sequences. As a result, the Izod impact strength was enhanced by 63% with 25% aramid fiber hybridization. It is also shown that there is an optimal point in laminated composite hybridization, [CF/CAF₂/CF]_s stacking sequence.

• Current Optics and Photonics
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• v.8 no.4
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• pp.382-390
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• 2024

Laser propagation through atmospheric disturbances is vital for applications such as laser optical communication, satellite laser ranging (SLR), laser guide stars (LGS) for adaptive optics (AO), and laser energy transmission systems. Beam degradation, including energy loss and pointing errors caused by atmospheric turbulence, requires thorough numerical analysis. This paper investigates the impact of laser beam parameters on ground-to-space laser propagation up to an altitude of 100 km using vertical atmospheric disturbance profiles from the Geochang SLR Observatory in South Korea. The analysis is confined to 100 km since sodium LGS forms at this altitude, and beyond this point, beam propagation can be considered free space due to the absence of optical disturbances. Focusing on a 100-watt class laser, this study examines parameters such as laser wavelengths, beam size (diameter), beam jitter, and beam quality (M²). Findings reveal that jitter, with an influence exceeding 70%, is the most critical parameter for long-exposure radius and pointing error. Conversely, M², with an influence over 45%, is most significant for short-exposure radius and scintillation.

• Journal of Korea Technology Innovation Society
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• v.9 no.3
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• pp.606-625
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• 2006

This Study is to show the impact of IT capital stock accumulation on the total factor productivity in 9 industries during 1980 through 2000. We construct the If capital stock using input and output table provided by Bank of Korea (2000). Using sequence testing methodologies, we investigate the nonstationary characteristics of the relevant data and test the cointegration relationship between total factor productivity and IT capital stock. Over the past two decades, IT capital stock contributed between 0.19 to 0.07 percentage point per IT capital stock on total factor productivity. Our empirical results, therefore, do not support Solow's IT paradox in using the long period panel data case in Korea.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.228-230
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• 2006

While trains perform a complete precision stopping control at stop point, it is essential to keep better commuters comfort in prompt. Because a train's brake force tends to increase a brake effort in a low speed and a low brake effort, a brake force in motor cars must be increased to keep better passenger comfort, to control the special braking qua1ities and to prevent the impact of the automatic coupler rather than trailer's, Rail cars must have a special braking process for the train stopping control. In the train stop mode, the train stopping control is designed to start at 20km/h. It starts by Dynamic brake blending, and then finally stops by only the friction. If these process are not exactly activated, the train may fail a complete precision stop. In this report, it studied the electric and friction brake processing during the precious stopping control. To achieve exact test results, the speed reference has to be reduced the calculated difference. In the precision stopping control. the ways of the keeping brake force in motor car was analyzed and some solutions of controling air pressure was brought up by means of direct test in main line, This study was based on line 5 in Seoul Metropolitan subway.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.4
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• pp.205-211
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• 2020

The study aims to assess factors affecting intention to purchase green products in Vietnam. The study employs samples from customers who have actually experienced green consumption in Vietnam. The samples were collected by convenient sampling methods. The survey obtained 206 responses with full information. The survey was conducted from October 2019 to January 2020. The measurement scale was a 5-point scale with 1- completely disagree and 5- strongly agree. This study employs factor analysis and structural equation modelling analysis. The results showed that the social and environment sustainability awareness have positive effects on altruism of customers who are interested in green consumption. Altruism also has the same direction on green purchase intention. Besides, the attitude toward buying green and health consciousness affects green purchase intention. At the same time, the altruism and attitude towards buying green products also influence positively on green purchase intention. Besides, the health consciousness positively affects attitude towards buying green products. The results show that the health consciousness has a negative impact on intention to purchase green products. The findings suggest that it is necessary to raise customers' health consciousness, customers' altruism from disseminating knowledge about environmental protection as well as society to enhance the green consumption in Vietnam.

• The Journal of Industrial Distribution & Business
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• v.9 no.1
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• pp.39-49
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• 2018

Purpose - This present aims to analyze the effect of export modes on initial export amount and time to export by selecting export modes among various success strategies and factors. Research design, data, and methodology - It surveyed 980 small and mid-sized venture enterprises across Korea. The export modes and its impact on exports through frequency analysis and cross analysis, and validated through a PPML(regression analysis applied the enterprise growth model) analysis. Results - Five export modes were investigated : direct export, indirect export, transfer from direct export to indirect export, transfer from direct export to indirect export, and parallel export to indirect export. It was found that SMVEs that exported directly from establishment to initial export had the shortest period, and also had the highest export price Conclusions - From a marketing point of view, it took an average of 1.6 years to switch from export directly to indirect export or directly export, and the reason for the export modes conversion was to supplement export specialists and improve export competitiveness. And the export amount and time period that SMVEs establishes and export is a significant factor in export success strategy and there has been few prior study in export modes.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.2
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• pp.132-138
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• 2018

Aviation safety requires systematic national attention and management because aircraft accident produce greater undesired social impact, economical damage, and declining national credibility compare to other transportation accident. Specially, Republic of Korea has highly increased risk of air accident as a major air transportation point having small aerospace, connecting pacific ocean and Asia, and explosively increased air traffic produced by economical growth, operating numerous military aircraft for the South and North Koreas' confrontational situation. Also, greatly increased domestic and oversea air travels by Koreans and foreigners as well as air freight based on heightened Korea's national power, launching new low cost carriers, and popularized leasure aviation have produced large amount of aviation needs in various fields. However, national aviation safety management system gratifying increased aviation needs and aircraft operations is seem to be slow in progress. This paper will show optimized measures utilizing private, governmental, and military resources to prevent aircraft accident under circumstances of limited budget and an favorable conditions, then will propose several action items.

• Journal of Korean Library and Information Science Society
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• v.45 no.2
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• pp.5-27
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• 2014

This study aims to investigate the relationship between university library usage and educational achievement of academic library users. To proceed with this study, academic library usage data were collected from S university undergraduate students. Academic achievement was measured using the students' grade point average(GPA). T-test and analysis of variance were used to compare differences of means between library usage and academic achievement with the background variables. Hierarchical regression analyses were conducted to determine the association between library usage and academic achievement. As a result, a positive correlation was found between academic achievement and the use of library resources and services according to gender, year and academic subject. In addition, academic library usage had a positive significant influence on academic achievement. Students who used more library resources and facilities ultimately get better grades.

• Korean Journal of Environment and Ecology
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• v.28 no.2
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• pp.247-252
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• 2014

This study was conducted to provide information which will be useful for managing the forest trails effectively. To investigate users' attitudes toward the forest trail construction and use, a questionnaire survey was employed in the Jirisan Dulegil. As the results, most of the respondents perceived that the Jirisan Dulegil have positive impact economically and socio-culturally on community growth. Contrastively, a negative perception existed in the environmental aspect. The users' satisfaction level regarding the Jirisan Dulegil appear to be positive. Users' satisfaction level regarding use services provided in community boundary was evaluated relatively lower. In this point of view, trail use service system provided in the community should be reconsidered for effective forest trail management.