• Journal of Electrical Engineering and Technology
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• v.3 no.2
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• pp.143-151
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• 2008

This paper presents the operation of Fuel Cell Distributed Generation(FCDG) systems in distribution systems. Hence, modeling, controller design, and simulation study of a Solid Oxide Fuel Cell(SOFC) distributed generation(DG) system are investigated. The physical model of the fuel cell stack and dynamic models of power conditioning units are described. Then, suitable control architecture based on fuzzy logic and the neural network for the overall system is presented in order to activate power control and power quality improvement. A MATLAB/Simulink simulation model is developed for the SOFC DG system by combining the individual component models and the controllers designed for the power conditioning units. Simulation results are given to show the overall system performance including active power control and voltage regulation capability of the distribution system.

• Journal of Power Electronics
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• v.5 no.3
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• pp.180-189
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• 2005

In this paper a DSP based control scheme for the interleaved boost converter is presented. The mathematical model for the interleaved boost converter operating in a continuous inductor current mode is developed. A state-space averaging technique is used for modeling the converter system. A fixed frequency sliding mode controller is designed to ensure current distribution between the two converter modules and to achieve the load voltage regulation simultaneously. Necessary and sufficient conditions, using variable structure theory, are derived for the sliding mode to exist. The range of sliding mode controller coefficients is also determined. The designed controller capability, load distribution among the individual boost cells and load voltage regulation against source and load disturbances, are demonstrated through PSIM simulation results. A real-time controller based on ADMC401 DSP is developed. Experimental results are provided to validate the proposed control scheme.

• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.127-134
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• 1996

Recently, in Korea the birthrate is declining and the average life span has been increasing. Thus, compared to the previous periods nowadays, older people are required to work. Even elderly people are rejoining the workforce. Korean companies set the retirement age between 55 and 60 years of age, however, accidents occur frequently. Thus, it becomes necessary to evaluate the ability of the elderly person. Since the required function of the worker varies from job to job the evaluation of the capability must also be conducted according to the desired functions. One of the methods used in this study is the continuous control knob to evaluate the tracking control ability to investigate the relationship of manual dexterity and age. The result of the study Indicates that the manual dexterity decreases with age. However, there are differences among individuals. The individuals lifestyle affected the manual dexterity of that individual. As a result, a company may use the manual dexterity as an measure to evaluate the elderly persons work ability.

• KSCI Review
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• v.14 no.1
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• pp.213-219
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• 2006

We need the customized e-Learning service according to not only developing the wireless mobile and hardware technology, also developing the multimedia process skills. Especially, the beginner who start to learn the first programming course must be provided the personalized learning. The beginner require the repeated practices to obtain the programming skills, also they reveal the different learning effects following the learner capability In this paper. we develop a new e-Learning contents which give the individual service for learner and show the simulation which is program execution to maximize the learning effects.

• KSCI Review
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• v.2 no.1
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• pp.109-120
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• 1995

The purposes of this paper are to construct the author tools that have influence on system package in EXSYS professional, to design the objects and the roles of development members on the phases of development life cycle, to study on the increase of efficiency in the main phases that have much influence on the efficiency of authoring tool development. The major factors which affect authoring tool are as follow : the size of the product, the individual capability of project personnel, the project period, the complexity of the product, the required level of reliability and the level of technologies utilized.

• Current Optics and Photonics
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• v.5 no.3
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• pp.289-297
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• 2021

We describe a comb-mode resolving spectroscopic technique by direct time-domain phase correction of unstable interferograms obtained from loosely locked two femtosecond lasers. A low-cost continuous wave laser and conventional repetition rate stabilization method were exploited for locking carrier and envelope phase of interferograms, respectively. We intentionally set the servo control at low bandwidth, resulting in severe interferograms' fluctuation to demonstrate the capability of the proposed correction method. The envelope phase of each interferogram was estimated by a quadratic fit of carrier peaks to correct timing fluctuation of interferograms in the time domain. After envelope phase correction on individual interferograms, we successfully demonstrated 1 Hz linewidth of RF comb-mode over 200 GHz optical spectral-bandwidth with 10-times signal-to-noise ratio (SNR) enhancement compared to the spectrum without correction. Besides, the group delay difference between two femtosecond pulses is successfully estimated through a linear slope of phase information.

• Journal of Information Technology Applications and Management
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• v.28 no.2
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• pp.17-33
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• 2021

Korean society is changing into multicultural society with increasing international marriage and immigrant influx. The increasing number of immigrants in Korean society suggests the necessity of social and economic integration of people with diverse cultural backgrounds. We study the entrepreneurial intention of multicultural immigrant. Cultural intelligence is closely related with sustainable value and belief to their eagerness in surviving of the 2nd country. Cultural intelligence is the individual's capability to function or manage effectively in different cultural settings or in multicultural settings. It is assumed that the cultural intelligence of multicultural immigrant might affect the entrepreneurial intention. Based on the theory of planned behavior, we set up the research model. 243 usable responses of multicultural immigrants in Korea were analyzed. Our findings suggest that cultural intelligence positively affected entrepreneurial intention by affecting subjective norm and perceived behavior control. This study contributed the study of the entrepreneurial intention and multicultural immigrant.

• Journal of information and communication convergence engineering
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• v.18 no.4
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• pp.254-259
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• 2020

Phased-array antennas comprise a demanding antenna design methodology for commercial wireless communication systems or military radar systems. In addition to these two important applications, the phased-array antennas can be used in beamforming for wireless charging. In this study, a four-way analog beamforming front-end module (FEM) for a hybrid beamforming system is developed for 2.4 GHz operation. In a hybrid beamforming scheme, an analog beamforming FEM in which the phase and amplitude of RF signal can be adjusted between the RF chain and phased-array antenna is required. With the beamforming and beam steering capability of the phased-array antennas, wireless RF power can be transmitted with high directivity to a designated receiver for wireless charging. The four-way analog beamforming FEM has a 32 dB gain dynamic range and a phase shifting range greater than 360°. The maximum output RF power of the four-way analog beamforming FEM is 40 dBm (=10 W) when combined the four individual RF paths are combined.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.4
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• pp.294-303
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• 2023

During wartime, the operation of engineering equipment plays a pivotal role in bolstering the combat prowess of military units. To fully harness this combat potential, it is imperative to provide efficient support precisely when and where it is needed most. While previous research has predominantly focused on optimizing equipment combinations to expedite individual mission performance, our model considers routing challenges encompassing multiple missions and temporal constraints. We implement a comprehensive analysis of potential wartime missions and developed a routing model for the operation of engineering equipment that takes into account multiple missions and their respective time windows of required start and completion time. Our approach focused on two primary objectives: maximizing overall capability and minimizing mission duration, all while adhering to a diverse set of constraints, including mission requirements, equipment availability, geographical locations, and time constraints.

• Composites Research
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• v.37 no.2
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• pp.139-142
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• 2024

This study explores the impact of polymer blending on the mechanical properties and triboelectric energy harvesting capability of composite polymers. A multifunctional free-standing polymer blend composed of poly(vinyl alcohol) (PVA) and poly(diallyldimethylammonium chloride) (PDDA) was fabricated using a polymer casting method. Stress-strain analysis of the polymer blend revealed an enhanced stretchability of 308.4% with excellent transparency. Furthermore, triboelectric analysis revealed dynamic energy harvesting capabilities with impressive electrical voltage and current output of 50 V and 5 μA. These results represent a significant improvement compared to individual PVA and PDDA polymers and highlight the potential of polymer blending to enhance both mechanical and electrical properties for energy harvesting applications.