• Journal of Power Electronics
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• v.16 no.4
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• pp.1438-1454
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• 2016

Because the nonlinear and time-varying characteristics of continuously variable transmission (CVT) systems driven by means of a six-phase copper rotor induction motor (CRIM) are unconscious, the control performance obtained for classical linear controllers is disappointing, when compared to more complex, nonlinear control methods. A blend modified recurrent Gegenbauer orthogonal polynomial neural network (OPNN) control system which has the online learning capability to come back to a nonlinear time-varying system, was complied to overcome difficulty in the design of a linear controller for six-phase CRIM driving CVT systems with lumped nonlinear load disturbances. The blend modified recurrent Gegenbauer OPNN control system can carry out examiner control, modified recurrent Gegenbauer OPNN control, and reimbursed control. Additionally, the adaptation law of the online parameters in the modified recurrent Gegenbauer OPNN is established on the Lyapunov stability theorem. The use of an amended artificial bee colony (ABC) optimization technique brought about two optimal learning rates for the parameters, which helped reform convergence. Finally, a comparison of the experimental results of the present study with those of previous studies demonstrates the high control performance of the proposed control scheme.

• Journal of the military operations research society of Korea
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• v.31 no.2
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• pp.86-104
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• 2005

During the 'Cold War', DoD had focused on the high performance and timely acquisition which enabled quick field out the superior weapons than the enemy regardless of acquisition cost. But, after the cold war, the focus has been changed to the 'cost effective acquisition' of weapon systems because of tremendous investment cost & economic theory. The U.S. DoD has been tried to make 'the most effective acquisition system'(AR, Acquisition Reform) from mid-80's with their enough experienced program data, and as a result, they had launched the new acquisition procedure - DoD 5000 series - in 1996. DoD is continuously doing the study and making several improvements on the procedure after it had been once announced. On Oct 30. 2002, DoD noticed that they cancelled the DoD 5000 series documents(5000.1, 5000.2, 5000.2-R) and 5000.2-R will be reissued as a guide. The most recent version which focused on 1) evolutionary acquisition and spiral development, 2) procedure for future technology systems including software and IT, 3) supplement on the area of efficiency, flexibility, creativity and innovation of old system was issued by May 12. 2003. This article suggests a 'good idea' based on the reviewing of these DoD efforts for our defense acquisition regulation and procedure to go. It includes the CAIV concept application, IPT utilization, T&E method, cost or price based contract etc-all for the effective acquisition.

• Journal of Korea Multimedia Society
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• v.22 no.10
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• pp.1199-1207
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• 2019

Video surveillance data, which is used for preemptive or post-emptive action against any event or accident, is required for monitoring the location, but is reducing the capacity of the image data by removing intervals for cost reduction and system persistence. Such a video surveillance system is fixed in a certain position and monitors the area only within a limited angle, or monitors only the fixed area without changing the angle. At this time, the video surveillance system that is monitored only within a limited angle shows that the variation object such as the floating population shows different status in the image, and the background of the image maintains a generally constant appearance. The static objects in the image do not need to be stored in all the images, unlike the dynamic objects that must be continuously shot, and occupy a storage space other than the necessary ones. In this paper, we propose a mechanism to analyze the image, store only the small size image for the fixed background, and store it as image data only for variable objects.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.4
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• pp.355-361
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• 2011

The power control of the existing heating element has been using the On-Off control, phase control, and PWM control. In case of controlling power PTC heating element developed recently with the existing method, the temperature is unable to be precisely controlled or the harmful electromagnetic wave to human body is generated. In this paper, We suggest the power control of PTC heating cable using variable AC Cycles. This regards the AC cycle of N as the unit of the power control. It determines On-Off for each cycle. It is the AC power control method in which it arranges the on-cycle in N cycles in the random and it supplies the current continuously. At this time. the minimal electric power amount becomes 1/N. The maximum current amount becomes 1 and sets up the number of on cycles according to the set value and can control the electric power with the step of N consistently. In the PTC heating system, we show that proposed power control method is superior in the EMI and temperature control property using MATLAB simulation, experiments and measurements.

• Journal of Aerospace System Engineering
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• v.15 no.3
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• pp.79-86
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• 2021

For a preliminary study on a thrust-throttleable Variable Flow Ducted Rocket, a gas generator and flow control valve were developed, and ground combustion tests were performed. The gas generator and flow control valve operated at the required performance level for parameters, such as heat-resistance, combustion-time, pressure, and temperature. The combustion characteristics of a fuel-rich solid propellant mixed with Boron/MgAl/AP, etc., were also analyzed. A Plunger-type flow control valve was designed to control the discharge flow area, and it was confirmed that the flow control valve was able to control the combustion gas flow rate and pressure. However, due to the reduction of the discharge flow area caused by adhesion of combustion products, the combustion pressure continuously increased. The analysis of the pressure increase is covered in Part 2 of this paper.

• Macromolecular Research
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• v.14 no.1
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• pp.94-100
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• 2006

Although the peripheral nerve system has a relatively good regenerating capacity compared to the central nerve system, peripheral nerve repair remains a clinical challenge as restoration of normal nerve function is highly variable. Synthetic tubular nerve conduits were designed as an alternative repair method in order to replace the need for an isograft. These nerve conduits guide regenerating axons from the proximal toward the distal end, maintain within growth-promoting molecules released by the nerve stumps, and protect regenerating axons from infiltrating scar tissue. In this work, we prepared cinnamoylated alginate (CA)-collagen-chitosan nerve conduit using the lyophilization method to generate a controllable parallel channel in the center and then investigated its influence on peripheral nerve regeneration in an animal study. At 12 weeks after implantation, histological study showed that tissue cable was continuously bridging the gap of the sciatic nerve in all rats. Our newly developed nerve conduit is a promising tool for use in peripheral nerve regeneration and provides a suitable experimental model for future clinical application.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.6_2
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• pp.989-998
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• 2020

Recently, demands for large-capacity electronic loads are increasing in various industries such as a reliability test for the performance of a DC power supply device or a dummy-load for improving the stability of an independent microgrid to be actively built in the future. The electronic load required in these various fields requires an operation such as a continuously variable resistance load while minimizing the switching harmonic component generated in the electric load current in order to reduce the influence of interference from the load peripheral device. Electronic loads require a system that minimizes switching current ripple for load control. Therefore, in this paper, we propose a three-level module converter structure to reduce the current ripple of an electronic load, and a multilevel interleaved power converter topology to reduce the current ripple. The validity of the proposed electronic load, 3-level 6 interleaver converter, was verified by simulation and experiment. In addition, the user's convenience was provided by applying the emotional command curve interface method.

• Journal of Information Processing Systems
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• v.16 no.6
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• pp.1343-1358
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• 2020

In the stagewise arithmetic orthogonal matching pursuit algorithm, the weak threshold used in sparsity estimation is determined via maximum iterations. Different maximum iterations correspond to different thresholds and affect the performance of the algorithm. To solve this problem, we propose an improved variable weak threshold based on the stagewise arithmetic orthogonal matching pursuit algorithm. Our proposed algorithm uses the residual error value to control the weak threshold. When the residual value decreases, the threshold value continuously increases, so that the atoms contained in the atomic set are closer to the real sparsity value, making it possible to improve the reconstruction accuracy. In addition, we improved the generalized Jaccard coefficient in order to replace the inner product method that is used in the stagewise arithmetic orthogonal matching pursuit algorithm. Our proposed algorithm uses the covariance to replace the joint expectation for two variables based on the generalized Jaccard coefficient. The improved generalized Jaccard coefficient can be used to generate a more accurate calculation of the correlation between the measurement matrixes. In addition, the residual is more accurate, which can reduce the possibility of selecting the wrong atoms. We demonstrate using simulations that the proposed algorithm produces a better reconstruction result in the reconstruction of a one-dimensional signal and two-dimensional image signal.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1511-1519
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• 2014

The objective of this paper is to propose a modelling of a small compressed air energy storage system, which drives an induction generator based on a field-oriented control (FOC) principle for a renewable power generation. The proposed system is a hybrid technology of energy storage and electrification, which is developed to use as a small scale of renewable energy power plant. The energy will be transferred from the renewable energy resource to the compressed air energy by reciprocating air compressor to be stored in a pressurized vessel. The energy storage system uses a small compressed air energy storage system, developed as a small unit and installed above ground to avoid site limitation as same as the conventional CAES does. Therefore, it is suitable to be placed at any location. The system is operated in low pressure not more than 15 bar, so, it easy to available component in country and inexpensive. The power generation uses a variable speed induction generator (IG). The relationship of pressure and air flow of the compressed air, which varies continuously during the discharge of compressed air to drive the generator, is considered as a control command. As a result, the generator generates power in wide speed range. Unlike the conventional CAES that used gas turbine, this system does not have any combustion units. Thus, the system does not burn fuel and exhaust pollution. This paper expresses the modelling, thermodynamic analysis simulation and experiment to obtain the characteristic and performance of a new concept of a small compressed air energy storage power plant, which can be helpful in system designing of renewable energy electrification. The system was tested under a range of expansion pressure ratios in order to determine its characteristics and performance. The efficiency of expansion air of 49.34% is calculated, while the efficiency of generator of 60.85% is examined. The overall efficiency of system of approximately 30% is also investigated.

• Journal of Venture Innovation
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• v.6 no.3
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• pp.73-93
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• 2023

This study provides a prospect for the fast growing the smartwatch market by investigating the relationship between the satisfaction and the continuous use intention of Apple watch users, as well as the factors influencing their satisfaction. Based on the TAM, this study uses system quality, information quality, and self-efficacy as independent variables, perceived usefulness, perceived ease of use, and satisfaction as mediators, and continuous use intention as the dependent variable. We analyze the data of 256 individuals who completed an online survey with SPSS 26.0 and AMOS 26.0 software. This study conducts several tests and analyses to empirically evaluate the data including reliability analysis, factor analysis, feasibility analysis, path analysis, hypothesis verification, and mediation analysis. Our results investigate which factors may influence consumers' intention to continuously using Apple Watch devices in the future. In summary, satisfaction has a positive effect on the intention to continuously use smartwatchs. Perceived usefulness and perceived ease of use have a positive effect on satisfaction. Among the three factors (system quality, information quality, and self-efficacy), only self-efficacy has no significant impact on perceived usefulness but had a positive effect on perceived ease of use. In addition, system quality and information quality positively affect perceived usefulness, perceived ease of use, satisfaction, and continuous intention to use an Apple Watch. Taking the Apple Watch as the subject of our research topic, this study provides theoretical value by exploring the impact of user's satisfaction with their smartwatch on their continuous usage intention. This study further explains the influence of system quality, information quality, and self-efficacy on user satisfaction. Additionally, this research offers valuable insight to practitioners by confirming that information quality, system quality, and self-efficacy are important features for enhancing satisfactory user experiences which in turn may increase users' intention to continued using smartwatches.