• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.251-257
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• 2014

An actuator system is a type of motor designed to control a mechanism operated by a source of energy, in the form of an electric current by converting energy into some kind of motion. As audio actuators, transforming electric voltage signal into audio signal, speakers and amplifiers are commonly used. In applications of industry, high output power systems are required. For these systems to generate high-quality output, it is essential to control output impedance of audio systems. We have developed an adaptable power supply for driving active amplifier systems with variable loads. Depending on the changing values of resistance of the speaker which produces audible sound by transforming electric voltage signal, the power supply source of the active amplifier can generate the maximum power delivered to the speaker by an adaptable change of loads. The amplifier is well protected from the abrupt increment of peak current and an excess of current flow.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.1
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• pp.40-47
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• 1998

The optical heads as the key parts of digital audio/video players are applied extensively from general household electric appliances to computer memory or game apparatuses, and the demand of them tends to be increased according to the extension of optical medium market. In this paper, the 2-axis actuator, the key component for focus servo and tracking servo of the optical head is designed as a type of the cantilever suspended by 4 wires. The design propriety is verified through its simulation and the characteristic analysis of its mock-ups. The other factors which influence the performance of 2-axis actuators besides the design factors of them, are also verified through the mock-up analysis.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.91-97
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• 2012

Recently, the performances of electrical and electronic devices are improving while the sizes are becoming smaller. As sound-generating systems, the two-dimensional speakers have been developed in place of conventional three-dimensional ones. Piezoelectric materials show the mechanical vibrations due to the voltage applied from outside the materials. The early film speakers had a limitations of output power in that it was not easy to make the conducting macromolecular films on the surfaces of the materials due to the internal chemical properties of materials. We have adopted the corona surface treatment in order to improve the output characteristics by increasing the adhesion of the coating material on to the surface of the center material of piezo film. The results showed the improvement of output power in the wider range of operating frequencies.

• KIPS Transactions on Software and Data Engineering
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• v.5 no.9
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• pp.433-440
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• 2016

Railway point machines act as actuators that provide different routes to trains by driving switchblades from the current position to the opposite one. Since point failure can significantly affect railway operations with potentially disastrous consequences, early stress detection of point machine is critical for monitoring and managing the condition of rail infrastructure. In this paper, we propose a stress detection method for point machine in railway condition monitoring systems using sound data. The system enables extracting sound feature vector subset from audio data with reduced feature dimensions using feature subset selection, and employs support vector machines (SVMs) for early detection of stress anomalies. Experimental results show that the system enables cost-effective detection of stress using a low-cost microphone, with accuracy exceeding 98%.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.855-861
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• 2009

This paper presents the concept of dynamically reconfigurable space by introducing smart building components. Thanks to the advances in ubiquitous computing and ITC technology, we are able to expect, in the near future, the aspects of future buildings which may transform their appearance and states to perform specific functions. In other words, it is certain that the building space will actively reconfigure itself to accommodate user's needs once we acquire proper technologies. Based on the assumption that building components may not be transformed through the magical process, but change its physical states (e.g. transparency, illumination, display contents, etc.) and functions of embedded devices (e.g. audio, actuators, sensors, etc.), we can envision a dynamically reconfigurable smart space. In order to conceptualize such spaces, critical surveys have been conducted on current works of leading architects. When the room needs to be used as a specific function room, the components need to change theirs states or to behave in a certain manner to create an optimum environment. Our model defines the relationships and elements to describe the mechanism of reconfigurable space. We expect this model provides a conceptual guideline for developing a smart building components based on spatial service scenarios. Therefore, a future smart spaces implemented by integrating various technologies are not designed in deterministic manner, so that spatial functions are expanded without constrained by physical existence.