• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.5
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• pp.74-80
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• 2013

This paper presents the transient behavior of the switching surge voltages generated by interruption of DC ground fault currents flowing through metal flexible conduits. All fault circuits consist of line parameters such as resistance, inductance, capacitance and conductance. The use of nonmagnetic metal conduits should be taken into account in order to reduce the inductance of battery charger distribution circuits. The frequency-dependent circuit parameters of metal flexible conduits were measured. The switching surge voltages generated at the ground fault circuit consisted of steel-galvanized alloy and aluminium conduits were investigated. As a result, the impedances of metal flexible conduits are significantly increased over the range of the frequency above 10 kHz and the switching surge voltages generated along aluminium flexible conduit are lower than those along steel-galvanized alloy conduit when DC fault current is interrupted.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.220-225
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• 2013

In this study, active control system using sliding mode control method is presented to achieve the gust response alleviation of a three-dimensional flexible wing model. For this purpose, aeroservoelastic model which is composed of aeroelastic plant, control surface actuator model, and gust model depicting the atmospheric turbulence is formulated in the state space. The aerodynamic force generated by the motion of a trailing edge control surface of a flexible wing is made use of as control means. An active control system combining state feedback sliding mode controller and state estimator based on measured responses such as wing tip acceleration and wing root strain is designed for gust response alleviation of a flexible wing aeroservoelastic model. The performance of the controller designed is demonstrated via numerical simulation for the representative flexible wing model under gust loading conditions.

• Korean Medical Education Review
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• v.23 no.3
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• pp.147-153
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• 2021

The coronavirus disease 2019 (COVID-19) pandemic made it necessary for medical schools to restructure their curriculum by switching from face-to-face instruction to various forms of flexible learning. Flexible learning is a student-centered approach to learning that has received interest in many educational sectors. It is a critical strategy for expanding access to higher education during the pandemic. As flexible learning includes online, blended, hybrid, and hyflex learning options, learners have the opportunity to select an instruction modality based on their needs and interests. The shift to flexible learning in medical education took place rapidly in response to the COVID-19 pandemic, and learners, instructors, and schools were not prepared for this instructional change. Through the lens of the technology acceptance model, human agency, and a social constructivist perspective, I examine students, instructors, and educational institutions' roles in successfully navigating the digital transformation era. The pandemic has also accelerated the use of advanced information and communication technologies, such as artificial intelligence and virtual reality, in learning. Through a review of the literature, this paper aimed to reflect on current flexible learning practices from the instructional design and educational technology perspective and explore emerging technologies that may be implemented in future medical education.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.9
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• pp.104-109
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• 2021

Tactile sensors and integrated circuits that detect external stimuli have been developed for use in various industries. Most tactile sensors have been developed using the MEMS(micro electro-mechanical systems) process in which metal electrodes and strain sensors are applied to a silicon substrate. However, tactile sensors made of highly brittle silicon lack flexibility and are prone to damage by external forces. Flexible tactile sensors based on polydimethylsiloxane and using a multi-walled carbon nano-tube mixture as a pressure-sensitive material are currently being developed as an alternative to overcome these limitations. In this study, a manufacturing process of pressure-sensitive materials with low initial electrical resistance is developed and applied to the fabrication of flexible tactile sensors. In addition, flexible tactile sensors are developed with pressure-sensitive materials dispensed on a substrate with flexible mechanical properties. Finally, a study is conducted on the change in electrical resistance of pressure-sensitive materials according to the modulus of elasticity of the substrate.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.20-23
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• 1996

This paper deals with the flexible manipulator with rotational and translational degrees of freedom, which has an arm of time-varying length with the prismatic joint. The tracking control problem of the flexible manipulator is considered. First we design the controller of the 2-type robust servo system based on the finite horizon optimal control theory for the trajectory planned as a discontinuous velocity. Next, to reduce the tracking error, we use the method of the dynamic programming and of modifying the reference trajectory in time coordinate. The simulation results show that the dynamic modeling is adequate and that the asymptotic stabilization of the flexible manipulator is preserved in spite of nonlinear terms. The PTP control error has been reduced to zero completely, and the trajectory tracking errors are reduced sufficiently by the proposed control method.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.383-386
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• 1997

Electrostatic suspension is a method to levitate an object by using electrostatic forces. Its main advantage is to levitate objects without any mechanical contact which fulfills the requirement of an object handling in ultra clean environment. In this paper, the electrostatic suspension system for film-like thin plate such as aluminum sheet, is designed and controlled. In contrast with the conventional electrostatic suspension system which requires the costly and bulky high-voltage amplifiers, it is suggested to use the switching voltage control method in consideration of real industrial application for the handling of such flexible bodies. Some experimental results show that the developed electrostatic suspension system shows good performances to levitate flexible film-like thin plate.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1711-1716
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• 2004

This paper presents identification and control of a 10-m antenna via accelerometers and angle encoder data. Artificial Neural Networks can be used effectively for the identification and control of nonlinear dynamical system such as a large flexible antenna. Some identification results are shown and compared with the results of conventional prediction error method. And we use a neural network inverse model for control the large flexible antenna. In the neural network inverse model, a neural network is trained, using supervised learning, to develop an inverse model of the antenna. The network input is the process output, and the network output is the corresponding process input. The control results show the validation of the ANN approach for identification and control of the 10-m flexible antenna.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.389.1-389.1
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• 2016

The flexible solid state device has been widely studied as portable and wearable device applications such as display, sensor and curved circuits. A zero-bias operation without any external power consumption is a highly-demanding feature of semiconductor devices, including optical communication, environment monitoring and digital imaging applications. Moreover, the flexibility of device would give the degree of freedom of transparent electronics. Functional and transparent abrupt p/n junction device has been realized by combining of p-type NiO and n-type ZnO metal oxide semiconductors. The use of a plastic polyethylene terephthalate (PET) film substrate spontaneously allows the flexible feature of the devices. The functional design of p-NiO/n-ZnO metal oxide device provides a high rectifying ratio of 189 to ensure the quality junction quality. This all transparent metal oxide device can be operated without external power supply. The flexible p-NiO/n-ZnO device exhibit substantial photodetection performances of quick response time of $68{\mu}s$. We may suggest an efficient design scheme of flexible and functional metal oxide-based transparent electronics.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.10 no.3
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• pp.178-183
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• 2010

In this study we augmented a virtual object to an image of a flexible surface such as a paper, which is acquired from a web camera. To get more presence feeling, we consider realistic illumination on augmenting. To get the geometric relation between the camera and the flexible surface, we use markers that are printed on the surface. Using marker information in prior, three dimensional coordinates of the surface can be calculated. After the marker is removed from the input image, we attach a two dimensional texture and shadow to the flexible surface by considering realistic illumination.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.3
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• pp.281-287
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• 2001

Traditional job shop scheduling is supposed that machine has a fixed processing job type. But actually the machine has a highly utilization or long processing time is occurred delay. Therefore product system is difficult to respond quickly to the change of products or loads or machine failure etc. Here we use flexible job shop which is supposed that a machine has several jobs by tool change. The heuristic for the flexible job shop scheduling has to solve two problems. One is a routing problem which is determine a machine to process job. The other is sequencing problem which is determine processing sequence. The approach to solve two problems arc a hierarchical approach which is determined routing and then schedule, and a concurrence approach which is solved concurrently two problems by considering routing when it is scheduled. In this study, we simulate for flexibility efficiency fo flexible job shop scheduling with machine failure using hierarchical approach.