• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.340-343
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• 1992

Fundamental positioning characteristics of a dual-axis Sawyer linear motor are described. The Sawyer motor is capable of high positional accuracy. An electronic control unit of the motor whose velocity is proportional to the frequency of the electric current was produced in our laboratory. The positioning system was constructed using two Sawyer motors, an air bearings suspension unit and an electronic control unit. The stable motion of the motor was confirmed on the open loop operation. The adjustable operating conditions were the live load of 1 kg, the maximum acceleration of 1.2G and the maximum velocity of 350 mm/s. Absolute positioning accuracy was improved within .+-.5.mu.m, on microstep operating conditions of dividing one pitch of 508.mu.m into 508 steps. The following two conclusions were obtained. An accelerating-cruising-decelerating control is effective for reduction in the travel time required. Also, microstep operation is effective for improving the resolution of position.

• Journal of Magnetics
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• v.19 no.3
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• pp.300-308
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• 2014

This paper develops a moving-magnet electromagnetic actuator for fast steering mirror (FSM). The actuator achieves a reasonable compromise between voice coil actuator and piezoelectric actuator. The stroke of the actuator is between the strokes of a piezoelectric actuator and a voice coil actuator, and its force output is a linear function of air gap and excitation current within our FSM travel range. Additionally, the actuator is more reliable than voice coil actuator as the electrical connection in the actuator is static. Analytically modeling the actuator is difficult and time-consuming. Alternatively, numerous finite element simulations are carried out for the actuator analysis and design. According to the design results, a real prototype of the actuator is fabricated. An experimental test system is then built. Using the test system, the force output of the fabricated actuator is evaluated. The test results validate the actuator analysis and design.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1454-1460
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• 2009

Ultra-speed tube train, which runs in vacuum atmosphere to overcome aero-dynamic dragging force, is considered as a high-speed ground transportation system to back up long-distance air travel. To realize the ultra-speed tube train, feasibility study of currently available Maglev technologies especially for propulsion and levitation system is needed. Propulsion by linear synchronous motor(LSM) and levitation by electro-dynamic suspension(EDS) which are utilized in the Japan's MLX system could be one of candidated technologies for ultra-speed tube train. In the LSM-EDS system, the key component is superconducting magnet, and its reliability and performance is very important to guarantee the safe-operation of Maglev. As the initiative of the feasibility study, this paper deals with the basic structure of superconducting magnet and core technologies to design and operate it. And by surveying the current R&D achievement in Korea, the nation's capability to develop advanced superconducting magnet for Maglev is presented.

• Journal of radiological science and technology
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• v.43 no.4
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• pp.289-295
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• 2020

This study investigated the feasibility of establishing a college of medicine in the western region of Chungnam to fill the gap in the medical doctor in charge of essential medical care in the region. Currently, the level of medical services in Chungnam is low compared to provinces across the country and in particular, 7 cities and towns, which account for 760,000 people, one-third of Chungnam's population, are located in the western regions of Chungnam. Because of this, in the event of an emergency patients, it is necessary to travel to Cheonan, Daejeon, Seoul, etc. where the regional emergency medical center is located for more than 1 hour and 30 minutes. In the case of critically ill and emergency patients transfer, it is a situation that misses the golden time and causes valuable loss of life. In order to improve the medical environment in the western region of Chungnam and improve the lives of residents in vulnerable areas of medical services, it is believed that establishing a college of medicine in the western region of Chungnam is essential.

• Human Ecology Research
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• v.53 no.4
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• pp.375-390
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• 2015

This study was designed to understand the residential experience of Korean women living in tropical country. For qualitative research, interviewees were selected by snowball sampling among Korean women living in Malaysia for over 20 years. The selection criteria for interviewees included husband's nationality, occupational experience, future living plan, frequency of travel to Korea. In-depth group and individual interviews were conducted from August 23 to October 7 2014. Subsequently (1) interviewees' general residential experiences in Malaysia were summarized, (2) interviewee's identity and lifestyle with housing pathways approach were clarified, (3) interviewees' residential experiences in 5 issues, reciprocity in residential area, intention of environmental change, meaning of housing and interaction, housing adaptation, and residential satisfaction/dissatisfaction were prescribed and interpreted. In conclusion, the reflection of interviewees' experiences in tropical country, suggested variations of housing structure type within a residential complex, air well and pocket by setback in building block for improving ventilation and noise prevention from neighbors, and ceiling fans in the house were suggested for the upcoming subtropical climate in Korea. Full option and minus options were also suggested for the presale market to reduce before occupancy remodeling needs. The research results implies valuable suggestions for a multicultural society, ecological housing and stronger communities.

• Asian Journal of Business Environment
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• v.11 no.4
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• pp.5-16
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• 2021

Purpose: This study aims to investigate the impact of auditor-client traffic convenience on accrual -based and real earnings management of the client firms. Research design, data and methodology: Using a sample of firms listed in Shanghai and Shenzhen Stock Exchanges over the period of 2007 to 2018, this paper empirically investigates the association between auditor-client traffic convenience and earnings management. We use three measures of auditor-client traffic convenience: railway traffic convenience, expressway traffic convenience, and air traffic convenience. The accrual-based earnings management is measured by abnormal accruals estimated by industry and year using the Modified Jones Model. Results: Findings indicate that traffic convenience is conducive to detecting and restraining positive accrual earnings management and real earnings management. After changing the measurement of independent variable and dependent variable, including potential omitted variables, the results are statistically unchanged. Further, the research shows that traffic convenience can not only improve audit quality, but also lead to higher fee premiums. Auditors didn't share with clients the cost reduction benefits caused by traffic convenience. Conclusions: Traffic convenience provides auditors with easy access to the client firms, alleviating the information asymmetry and improving corporate earnings quality. The findings have implications for regulators, audit practitioners and stakeholders.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.113-118
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• 2020

Recently, eco-friendly electric motorcycles have been considered to replace aging gasoline motorcycles to reduce the amount of suspended fine dust in air. However, existing rechargeable battery-powered electric motorcycles have been found unacceptable by users because of their many limitations, such as long charging time, short travel distance per charge, and low driving speed. To overcome the drawbacks of conventional electric motorcycles, this paper proposes an exchangeable battery-powered electric motorcycle and a new frame shape for housing the exchangeable battery. The proposed frame is similar to that of current electric motorcycles; however, the shape and position of the saddle support, battery, and controller mount section are redesigned. The safety of the presented frame is verified through static and dynamic analyses using ABAQUS. In particular, the dynamic analysis is conducted under the most extreme condition among the various operating situations, thus confirming the robustness of the proposed frame design.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.6
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• pp.2031-2048
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• 2021

Not only can air pollution reduce the overall competitiveness of tourist destinations, but also changes tourists' travel decisions, thereby affecting the tourism flows. The study presents a machine learning method to analyze how the haze pollution puts spatial effect on tourism flows in China from 2001 to 2018, and reveals the regional differences in heterogeneity among eastern, central, and western China. Our investigation reveals three interesting observations. First, the Environmental Kuznets Curve of the impact of haze pollution on tourism flows is not significant. In the eastern and western regions, the interaction between haze pollution and domestic tourism flows as well as inbound tourism flows shows an inverted U-shaped curve respectively. Second, there is an significantly positive spillover effect of tourism flows in all of the eastern, central, and western regions. As to the intensity of spillover, domestic tourism flows is higher than that of the inbound tourism flows. Both of the above figures are greatest in the eastern. Third, the Chinese haze pollution mainly reduces the inbound tourism flows, and only imposes significantly negative direct effects on the domestic tourism flows in the central region. In the central and eastern regions, significantly negative direct effects and spillover effects are exerted on inbound tourism.

• Journal of Distribution Science
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• v.21 no.4
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• pp.21-33
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• 2023

Purpose: To study, analyze, and investigate how to improve the service quality distribution and perceived value of passenger loyalty in low-cost airlines in Thailand. Research Design, data, and methodology: The data was collected from low-cost airline passengers who had used low-cost airlines within Thailand more than twice in the last 12 months. In total, 632 questionnaires were received, representing 97.32%, and in-depth interviews were done using the semi-structured technique. The key informants were either executives or representatives from 4 low-cost airlines operating in Thailand. We utilized structural modeling techniques to examine the data relevant to the investigation. Results: The results show that low-cost airline passengers in Thailand have strong opinions about the perceived value of the passenger loyalty of low-cost airlines within this sector of the Thai air travel industry. The variables were sorted in order of importance and included passenger loyalty, satisfaction, trust, perceived value, and service quality distribution. The relationship between the service quality distribution variables and the significance in relation to passenger loyalty according to low-cost airlines in Thailand showed that service quality distribution had a positive effect on perceived value and that passenger satisfaction has a direct positive effect on passenger loyalty. Conclusions: The 8 QPSTL strategy is successful in terms of service quality distribution and passenger satisfaction, therefore it is an important aspect of low-cost airlines in Thailand.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.3
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• pp.10-16
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• 2023

Demand for air travel, which shrank sharply following the outbreak of the COVID-19, has recently recovered up to 80% before the spreading pandemic. As a result, the number of passengers are rapidly increasing again. However, financial difficulties and lack of skilled workers in the aftermath of a long-term recession and pandemic lead to a decrease in aviation safety awareness which is fundamental for safety culture. Consequently, this hazard can act as a potential risk factor for the global aviation industry preparing for a new leap forward in the post-pandemic era. Therefore, this study analyzed and defined the four key elements of aviation safety awareness; attitude, belief, perception, and value. Based on this analysis, this study combined the four key elements into the P-D-C-A cycle to derive what top management, middle managers, and workers should each do to continuously improve the positive safety culture.