• Journal of the Korean Solar Energy Society
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• v.28 no.5
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• pp.85-95
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• 2008

Photovoltaic conditioning systems normally use a maximum power point tracking (MPPT) technique to deliver the highest possible power to the load continuously when variations occur in the insolation and temperature. A unique method of tracking the maximum power points (MPPs) and forcing the boost converter system to operate close to these points is presented through deriving small-signal model and transfer function of boost converter considering input capacitor. This paper aims at modeling boost converter including fairly large equivalent series resistance(ESR) of input reservoir capacitor by state-space-averaging method and PWM switch model. In the future, properly designed controller for compensation will be constructed in 3kw real system for maximum photovoltaic power tracking control.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.3
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• pp.182-190
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• 2021

Computational simulations of turbulent flows around a model ship have been performed to investigate an influence of TVD schemes on the accuracy of advective terms associated with ship resistances. Several TVD schemes including upwind, second-order upwind, vanLeer, and QUICK as well as a nonTVD linear scheme were studied by examining temporal and spatial characteristics of accuracy transition in adjacent cells to the hull. Even though vanLeer scheme was the most accurate among TVD schemes in both structured and unstructured grid systems, the ratio of accuracy switch from 2^nd order to 1^st order in vanLeer scheme was considerable compared with the 2^nd order linear scheme. Also, the accuracy transition was observed to be overally scattered in the unstructured grid while the accuracy transition in the structured grid appeared relatively clustered. It concluded that TVD schemes had to be carefully used in computational simulations of turbulent flows around a model ship due to the loss of accuracy despite its attraction of numerical stability.

• Asian Journal of Business Environment
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• v.11 no.3
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• pp.5-19
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• 2021

Purpose: The purpose of this research is to study the role of life satisfaction, quality consciousness, and religiosity, which are integrated with the TRA Model to explain the switching intention of Muslim consumers to use Halal Cosmetics and Personal Care (HCPC). The second purpose is to investigate the relationship between variables used in this study to provide recommendations to HCPC producers about Muslim consumer behavior in the market. Research design, data, and methodology: The target population in this study is Muslims who live in Greater Jakarta. Data collection is carried out by the self-administered survey method based on the Purposive sampling technique, and the questionnaire is distributed online. The statistical analysis to test the research hypotheses is the Partial Least Squares - Structural Equation Model (PLS-SEM). Results: Life satisfaction, product quality consciousness, and religious commitment have a significant effect on attitude to switching but do not significantly influence the intention of switching to use HCPC. Conclusions: Life satisfaction, quality consciousness, and religiosity that represent individual factors indirectly affect the intention to switch to use HCPC. Thus, religious commitment influences attitude to switching both directly and indirectly.

• Journal of Information Technology Services
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• v.20 no.5
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• pp.55-71
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• 2021

Technostress management is increasingly getting important as ICT advances and infiltrates every job and task. Especially with the advent of COVID-19, workers had to switch to teleworking utilizing ICT extensively. In this study, we developed a research model explaining antecedents and their impacts on technostress in telecommuting context, especially under the COVID-19 situation. The result revealed that techno-complexity, techno-invasion, and techno-overload are the dominant factors that affect the negative psychological responses in the COVID-19 situation. Among them, we found that techno-overload maintain the most significant influence. It is due to the lack of instant feedback on workload allocations in telework and the lack of adjustment period with the sudden shift to telecommuting. In the case of techno-complexity, employees seem to experience difficulty acquiring new technical skills. Finally, the techno-invasion came out significant, signifying the infiltration of working space by home-related activities. The emotion-focused coping strategy had a moderating effect. In contrast, the problem-focused coping strategy had no significant effect, indicating that an appropriate emotional coping strategy is more important for workers undergoing extreme changes in the work environment. Subsequently, practical and theoretical implications, limitations, and future research directions are discussed.

• Korea Trade Review
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• v.47 no.6
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• pp.71-96
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• 2022

This research will study the conversion intention of the users in China from fuel vehicle to new energy vehicles through the empirical methods. To this end, a questionnaire survey was conducted with car users as the object, combined with the theory of user migration and the PPM model to analyze the impact of fuel vehicle users' conversion intention to new-energy vehicles factor. The results showed that purchase experience contains the moderating effect, in which perceived risk and switching costs had a greater impact on the groups without purchase experience, whereas social identity, perceived value, personal attitude, and willingness to switch had a greater impact on groups with the purchase experience. Among all five factors, perceived risk had no discernible impact on the switching intention, but social identity, perceived value, attitude toward switching, and switching costs all had discernible impact on the switching intention. This study expects to come out with sustainable advises for the future growth of new energy vehicles from the study of car users' switching intention and the collective difference test of purchasing experience.

• Information Systems Review
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• v.8 no.1
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• pp.159-179
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• 2006

With the advances in information technologies and the wide acceptance of IT outsourcing practices, subscription-based information & telecommunications services(ITS) become more available. Convergence and intensified industry competition have made it an imperative for the ITS providers to keep their current customers and acquire new customers at the same time. In this study, we developed a framework for effective customer management based on the factors influencing the post-purchase customer choice: stay with the present provider or switch to another one. Specifically, we classified the factors into four categories: Holding factors, Defect factors, Inducement factors, and Hurdle factors depending on the characteristics of the influence and direction of the influence. Based on the classification, we developed a post-purchase customer choice model for the subscription-based ITS providers. Then, we illustrated a possible application of the model in the context of the broadband Internet access service. The model could be used to increase the competitive advantage of service providers through the effective customer management in the subscription-based ITS market.

• Korean Journal of Labor Studies
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• v.17 no.1
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• pp.269-295
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• 2011

This paper is about the part-time work and related polices in Netherland, which increased the employment rate for the past 30 years with part-time job creation. Netherland has been successful in making part-time 'good' jobs. There were many factors which contributed to increaing part-time jobs such as market, institution, policies, and industrial relations. There was virtuous cycle between increase in the supply of female labor power and increase in the demand for part-time worker in the labor market. The policies were reinforced which protect part-time workers, introduced the incentive system which was favorable to part-time wokres, guaranteed the right to select working hours to workers. Particularly, the labor market, institutions and policies were created in the midst of the social dialogue. As the polder model has been persisted for almost 30 years, the switch to full-time work or long working-hour model would not be possible. As the poler model is a very specific model based on the Netherland's own social conditions, it is not easy to copy and transplant in other countries.

• Journal of IKEEE
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• v.26 no.3
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• pp.355-363
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• 2022

Korea is pursuing a plan to switch and expand energy sources with a focus on renewable energy with the goal of becoming carbon neutral by 2050. As the instability of energy supply increases due to the intermittent nature of renewable energy, accurate prediction of the amount of renewable energy generation is becoming more important. Therefore, the government has opened a small-scale power brokerage market and is implementing a system that pays settlements according to the accuracy of renewable energy prediction. In this paper, a prediction model was implemented using a statistical model and an artificial intelligence model for the prediction of solar power generation. In addition, the results of prediction accuracy were compared and analyzed, and the revenue from the settlement amount of the renewable energy generation forecasting system was estimated.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.2
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• pp.290-299
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• 2017

Reconfigurable flight control using various kinds of adaptive control methods has been studied since the 1970s to enhance the survivability of aircraft in case of severe in-flight failure. Early studies were mainly focused on the failure of actuators. Recently, studies of reconfigurable flight controls that can accommodate complex damage (partial wing and tail loss) in conventional aircraft were reported. However, the partial wing loss effects on the aerodynamics of conventional type aircraft are quite different to those of BWB(blended wing body) aircraft. In this paper, a reconfigurable flight control algorithm was designed using a direct model reference adaptive method to overcome the instability caused by a complex damage of a BWB aircraft. A model reference adaptive control was incorporated into the inner loop rate control system enhancing the performance of the baseline control to cope with abrupt loss of stability. Gains of the model reference adaptive control were polled out using the Liapunov's stability theorem. Outer loop attitude autopilot was designed to manage roll and pitch of the BWB UAV as well. A 6-DOF dynamic model was built-up, where the normal flight can be made to switch to the damaged state abruptly reflecting the possible real flight situation. 22% of right wing loss as well as 25% loss for both vertical tail and rudder control surface were considered in this study. Static aerodynamic coefficients were obtained via wind tunnel test. Numerical simulations were conducted to demonstrate the performance of the reconfigurable flight control system.

• Journal of the Korea Society of Computer and Information
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• v.14 no.3
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• pp.13-26
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• 2009

In this raper, We propose the alternative solution, RTOS-based system to replace the PLC 4hat has used the automation system for industrial processes. RTOS-based system is constructed the PC and RTOS as hardware and software. It overcomes the limit of PLC and guarantees the stability and reliability. Also, PC has better performance and cheaper than PLC when operating and constructing the system. For many manufactures, these benefits alone are all the reason they need to switch from PLC-based system to RTOS-based system. To use the RTOS-based System, the PLC program needs the conversion to the RTOS task. And how to transform is the most important issue. So, we propose conversion method through the system model. The system model defines the operation of each module as the task after the system divided into module. Because the system divided into modules can control, the performance and the functionality of system improve, and the system can deal with a problem easily when repairing and changing.