• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.361-365
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• 2005

Since the fuel cell uses the hydrogen for its fuel. it has no emission and higher efficiency than an internal combustion engine. Also fuel cell is much quieter than engine generator and generates heat much less than engine generator. So it has advantage of Army's 'si lent watch' capability and the ability to operate undetected by the enemy. The fuel cell hybrid system combines a fuel cell power system with an ESS. The ESS (e.g., batteries or ultracapacitors) reduces the fuel cell's peak power and transient response requirements. It allows the fuel cell to operate more efficiently and recovery of vehicle energy during deceleration. The battery has high energy density, so it has the advantage regarding driving distance. However, it has a disadvantage considering dynamic characteristic because of low power density. One other hand. the ultracapacitor has higher power density, so it can handle sudden change or discharge of required power. Yet. it has lower energy density. so it will be bigger and heavier than the battery when it has the same energy. This paper proposes the power management strategy for multi-power source fuel cell hybrid system. which is applied with the merits of both battery and ultra capacitor by using both of them simultaneous.

• Journal of Technology Innovation
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• v.19 no.3
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• pp.115-140
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• 2011

The fact that innovation activities of venture firms and start-ups play crucial role in driving industrial development and economic growth has significantly increased the importance of business incubator and techno-park which promote new businesses creations. This review paper aims at not only generating performance measurement index of business incubators but also categorizing performance determinants in accordance with three different theoretical perspectives of resource-based view, strategy patterns, and social networks. Futhermore, as future direction of research, this paper emphasizes structured research efforts on the critical effects of incubator's governance patterns, external and regional contexts, and analysis of government incubator policy.

• Smart Structures and Systems
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• v.6 no.7
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• pp.793-810
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• 2010

This paper addresses the control issue of vibratory MEMS-based gyroscopes. This study considers a gyroscope that can be modeled by an inner mass attached to an outer mass by four springs and four dampers. The outer mass itself is attached to the rotating frame by an equal number of springs and dampers. In order to measure the angular rate of the rotating frame, a driving force is applied to the inner mass and the Coriolis force is sensed along the y-direction associated with the outer mass. Due to micro-fabrication imperfections, including anisoelasticity and damping effects, both gyroscopes do not allow accurate measurements, and therefore, it becomes necessary to devise feedback controllers to reduce the effects of such imperfections. Given an ideal gyroscope that meets certain performance specifications, a feedback control strategy is synthesized to reduce the error dynamics between the actual and ideal gyroscopes. For a dual-mass gyroscope, it is demonstrated that the error dynamics are remarkably decreased with the application of four actuators applied to both masses in the x and y directions. It is also shown that it is possible to reduce the error dynamics with only two actuators applied to the outer mass only. Simulation results are presented to prove the efficiency of the proposed control design.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.403-405
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• 2007

This paper presents the over-modulation strategy and indirect vector control drive of NPC type PWM inverter. NPC inverter has three level phase voltage output.It can perform in high voltage through assembling switching components. It has less harmonics and surge voltage stress at motor terminals than the 2 level inverter in same switching frequency through 3 level voltage. The conventional railway vehicle has used the vector control to MI=0.907 and the slip-frequency control from MI=0.907 to six-step mode. The slip-frequency control has bad motive power and slow torque control response. But vector control has good motive power and can instant torque control. In this paper, output voltage is controlled linearly from linear region to six-step mode by using over-modulation strategy. And NPC inverter is used.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.6
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• pp.633-641
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• 2015

The ROM (roll over mitigation) system is a next-generation suspension system that can improve vehicle-driving stability and ride comfort. Currently, mass-produced safety systems, such as ESC (electronic stability control) and ECS (electronic control suspension), enable measurements of longitudinal and lateral acceleration as well as yaw rate through inertial sensor clusters, but they lack direct measurements of the roll angle. Therefore, in this paper, a roll angle estimation algorithm from ESC system sensors and tire normal force has been proposed. Furthermore, this study presents a method for roll over mitigation force distribution between the front and rear of a ROM system. Performance and reliability of the roll angle estimation and roll over mitigation force distribution were investigated through simulations. The simulation results showed that the proposed control algorithm and strategy are reliable during vehicle rollovers.

• The Research Journal of the Costume Culture
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• v.26 no.6
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• pp.966-981
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• 2018

Consumers' desire for beauty has become a driving force in the beauty service industry which was further developed through specialization and segmentation. Nail-care service, which is one of the beauty services, is showing rapid growth, and intense competition among salons has become apparent. Thus, service management method and marketing strategy are required for customer satisfaction. Therefore, in this study, we tried to classify the nail-care services on the basis of systematization and realization of its characteristics which are fundamental when developing management and marketing strategies. The subjects of this study were women in their 20s and above living in Seoul, Gyeonggi, and Incheon areas. As a result, the nail-care service factors are classified as "external environment" (interior, celebrity, newness), "internal environment" (equipment and products, cleanliness, and environment), "location" (location and transportation convenience), "reputation" (good reputation), "technician skill," "kindness," "relationship" (relationship, empathy, and affinity), and "price and discount." The consumer types of nail-care services were classified into three groups according to the degree of involvement of these concept systems. These results can be used as marketing basics and will be the basis for studying marketing strategies. However, the consideration of setting up a marketing strategy for each consumer type will be presented in a follow-up study.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.2
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• pp.49-61
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• 2019

As the technological gap amongst manufacturers decreases, the life cycle of products has shortened, and competition accelerates due to the development of technology, incumbent manufacturing companies face growth limitations. In order to overcome such business issues, manufacturing companies are increasingly interested in changes in business models and innovations, especially in the direction of providing services where they can maintain the competitive advantage of their products. In such context, this empirical study examines managerial leadership, differentiation strategies, and products and services pricing as 'servitization factors', which can be driving forces for moving into a new era of growth for Korean SMEs, focusing on the mediating effects of servitization competency. The results are as follows : First, it was confirmed that executive leadership, differentiation strategy, and information & communication technology capability have a direct effect on service sales. Second, the process competency, partnership competency, and ICT competency, which are presented as the service competence of SMEs, were found to play an important role in inducing service sales in managerial leadership, differentiation strategy, product and services pricing. It also emphasized the role of the public policy such as helping to foster SMEs as key partners in the expansion of social facilities and establishing platforms through ICT and data utilization for the convergence of manufacturing services.

• Journal of Drive and Control
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• v.16 no.2
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• pp.80-90
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• 2019

Fuel cell hybrid electric vehicle is an attractive solution to reduce pollutants, such as noise and carbon dioxide emission. This study presents an approach for energy management and control algorithm based on energetic macroscopic representation for a fuel cell hybrid electric vehicle that is powered by proton exchange membrane fuel cell, battery and supercapacitor. First, the detailed model of the fuel cell hybrid electric vehicle, including fuel cell, battery, supercapacitor, DC-DC converters and powertrain system, are built on the energetic macroscopic representation. Next, the power management strategy was applied to manage the energy among the three power sources. Moreover, the control scheme that was based on back-stepping sliding mode control and inversed-model control techniques were deduced. Simulation tests that used a worldwide harmonized light vehicle test procedure standard driving cycle showed the effectiveness of the proposed control method.

• Journal of Koreanology Reviews
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• v.1 no.1
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• pp.25-29
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• 2022

Economic growth is one of the significant benchmarks determining a country's sustainable growth. Before WWII, most countries perceived their priority in terms of military strength as they dedicated most of their efforts and resources to creating weapons of mass destruction. The current research aims to establish some of the significant factors that may have contributed to the sustainable and progressive economic growth of South Korea within the 60-year timeframe. Multiple prior studies have attributed the economic growth in South Korea to policy reforms that opened the country to foreign markets. The outstanding increase in the percentage of exports stands out as an indication of the improvement in the quality of goods produced in the country. Finally, in recent years, China has dedicated more resources to research and developments as a strategy to improve innovation within the country and its overall economic growth. Other issues of concern likely to undermine the prospects of the country's economic growth include the limited geographical size, aging population, and limited natural resources. As such, South Korea needs to emphasize innovation and improve the business environment as its main strategy for sustainable economic growth in the future to maintain its continuous economic miracle.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.66-68
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• 2022

As data utilization becomes increasingly important, not only private companies but also public institutions are making great efforts to promote data utilization. The chief data officer is a key element of data governance, a driving system that achieves policy goals by adjusting the functions of each department in the organization responsible for data policy. With the enforcement of the Data-based Administration Law, all public institutions, including the Ministry of National Defense, have designated data officers, but it is not enough to play a practical role as it is still in the early stages of introduction. In this study, the current status of the operation of the defense data officer system is checked, and development strategy to play a practical role are presented.