• Journal of the Korean Society for Precision Engineering
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• v.20 no.4
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• pp.92-102
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• 2003

To detect electrical faults of a TFT (Thin Film Transistor) panel for the LCD (Liquid Crystal Display), techniques of converting electric field to an image are used One of them is the PDLC (polymer-dispersed liquid crystal) modulator which changes light transmittance under electric field. The advantage of PDLC modulator in the electric field detection is that it can be used without physically contacting the TFT panel surface. Specific pattern signals are applied to the data and gate electrodes of the panel to charge the pixel electrodes and the image sensor detects the change of transmittance of PDLC positioned in proximity distance above the pixel electrodes. The image represents the status of electric field reflected on the PDLC so that the characteristic of the PDLC itself plays an important role to accurately quantify the defects of TFT panel. In this paper, the image of the PDLC modulator caused by the change of electric field of the pixel electrodes on the TFT panel is acquired and how the characteristics of PDLC reflect the change of electric field to the image is analyzed. When the holding time of PDLC is short, better contrast of electric field image can be obtained by changing the instance of applying the driving voltage to the PDLC.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.3121-3135
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• 2015

Owing to the increase in consumption of multimedia content and the improvement of device capacity, user demand for high-quality content has increased. However, it is difficult to transport such large amounts of content over the existing broadcasting network with limited bandwidth. To provide high-definition broadcasting, some studies suggest methods of transporting multimedia over heterogeneous networks after encoding content hierarchically. MPEG Media Transport (MMT), standardized by Moving Picture Experts Group (MPEG), is a solution that enables large-volume media transport over heterogeneous networks such as digital broadcasting networks and packet-switched networks. In the case of delivering a scalable encoded video over different networks, synchronization of each stream is an important issue. MMT defines a synchronization scheme, but does not contain sufficient functions to implement it. In this paper, we propose a synchronization scheme for media streams that are encoded hierarchically, divided into layers, and transported over heterogeneous networks. We implement our scheme using MMT and HTTP, and experimented using three encapsulated video streams with different durations. As a result, we show that the proposed scheme can reduce the waiting time to display high-quality video, relative to Dynamic Adaptive Streaming over HTTP-Scalable Video Coding (DASH-SVC) by requesting segments of enhanced layers after calculating the transmission time. Additionally, we find out that the selection of durations have a relation to the characteristics of the video.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.982-1004
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• 2017

The recent advances in the field of augmented reality (AR) have shown that the technology is a fundamental part of modern immersive interactive systems for the achievement of user engagement and a dynamic user experience. This survey paper presents the descriptions of a variety of the new AR explorations, and the issues that are relevant to the contemporary development of the fundamental technologies and applications are discussed. Most of the literature regarding the pertinent topics-taxonomy, the core tracking and sensing technologies, the hardware and software platforms, and the domain-specific applications-are then chronologically surveyed, and in varying detail, this is supplemented with the cited papers. This paper portrays the diversity of the research regarding the AR field together with an overview of the benefits and the limitations of the competing and complementary technologies.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.1
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• pp.137-147
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• 2006

In this study, shape memory alloy damper with characteristics of pseudoelastic hysteresis for helicopter rotor blades are investigated. SMAs can be available in damping augmentation of vibrating structures. SMAs show large hysteresis in the process of pseudoelastic austenite-martensite phase transformation which takes place while subjected to loading above the austenite finish temperature. Since SMAs display pseudoelastic hysteresis behavior over large strain ranges, a significant amount of energy dissipation is possible. A damper can be designed with SMA wires prestressed to a baseline level somewhere in the middle of the pseudoelastic stress range. An experimental study of the effects of pre-strain and cyclic strain amplitude as well as frequency on the damping behavior of pseudoelastic shape memory alloy wires are performed. The effects of the shape memory alloy damper on aeroelastic and ground resonance stability of helicopter are studied. In aeroelastic stability, the dynamic characteristics of blades related to pitch angle and the amplitude of lag motion for the rotor equipped with SMA damper were examined. The performance of SMA damper on ground resonance instability are presented through the frequencies and modal damping with respect to rotating speed.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.293-295
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• 2001

This paper describes an interactive educational software developed at Konkuk University. This software provides an educational opportunity for electrical engineering students at the junior level to expand their knowledge about fault analysis in power systems. The developed educational software has three main modules: 1) Z-building, 2) setting the type and location of the fault, 3) displaying the calculated fault currents, according to the given simulation options. The main features of this tool are the diversification of acquisition network data, the function of learning about the z-building procedures, and the dynamic display function of state vectors-all voltage/current phasor. To verity the effectiveness of the developed educational software, some case studies are performed.

• English Language & Literature Teaching
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• v.15 no.4
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• pp.109-136
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• 2009

This study investigates English medium instruction (EMI) in an institution of higher education in Seoul, Korea to see whether this course creates cultural correction (reproduction of inequitable relations of power in EMI settings) or cultural continuity (opportunities for transporting students into a third space and enabling them to explore cultural diversity and to create new knowledge for themselves). A single site where EMI is carried out, a class on fairy tales and child education taught by a native English speaking professor, was chosen because it was hypothesized that the professor would display some of her unconscious dominant cultural orientation. The results of the study show that there more cases of cultural correction than there were of cultural continuity. Cases of cultural correction included lack of knowledge about the local context, fixing Korean classroom discourse as if it were American classroom discourse, and reproducing orientalism in the local educational setting. Cases of cultural continuity included using comparison to consider the cultural reality of the milieu, creating new knowledge for the local milieu, and learning as a dynamic ongoing process. Implications of this research are discussed including the important realization that EMI should be managed by subject specialists who are trained in language education and have knowledge of the students' needs and discourse in the L1 and in the local context.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.845-846
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• 2006

In this paper, we describe a capacitive position sensing and motion control scheme of a MEMS scanner used for laser display application. The laser displays can be made by scanning laser beams much the same way a CRT scans electron beams. So the accuracy of the scanner motion determines the quality of the displayed image. The MEMS scanner under consideration is composed of electrostatic comb electrodes with initial gap and requires large driving voltage. Due to the under-damping and nonlinear driving characteristics, the scanner motion is subject to be an unwanted oscillation. For the linear scanner motion, we devise a differential charge amplifier and phase compensator. The experimental results show that the implemented feedback control system provides sufficient electrical damping and improves the dynamic performance of the scanner.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2001.05a
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• pp.106-111
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• 2001

Model house play an important role in the sale of apartments. However, model house can create social and environmental problems. Virtual reality's (VR) use for the creation of model house has been studied as a possible counter measure to these problems. Existing models don't satisfy consumers' queries. A virtual model house can give the experience of seeing a real home through simulation. Also, a virtual model house can allow a home buyer to change the furniture on display or the color of the walls to reflect the consumer's taste in the construction. The internal present condition system using absorption style virtual reality and open style virtual reality are the indispensable tools that are going to take the place of the current model home. A virtual model house is more profitable than a physical model house because of reduced costs and time savings. In addition, a virtual model house can offer new kinds of information that a physical model home can not. This study's purpose is to discuss the desired direction of the virtual model house in this crucial and dynamic period of development.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.4
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• pp.553-561
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• 2010

In flat panel display or semiconductor industries, they install the equipments with fine line width and high throughput for fabrication and inspection. The equipments are required to have the linear stage which can position the work-piece with high speed, fine resolution on wide range of motion. In this paper, a precision planar linear XY stage is proposed. The stage has a symmetric planar window configuration and is guided by air-bearings on granite plate. The symmetric planar window configuration makes the stage has robustness against dynamic and thermal disturbances. The air-bearings let the stage move smooth on straight guide bar and flat granite surface. The stage is actuated by linear motor with Halbach magnet array (HMA). HMA generates more confined magnetic flux than conventional array. The linear motors are optimized by using sequential quadratic programming (SQP) with the several constraints that are thermal dissipation, required power, force ripple and so on. The planar linear XY stage with the symmetric planar configuration and the linear motors is implemented and then the performance such as force ripple, resolution and stroke are evaluated.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.3
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• pp.25-31
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• 2003

In this paper, proposed is a control system for a galvanometer which is widely used fer laser display, laser processing and marking systems. The galvanometer with mirror is modeled as a second-order dynamic system Based on frequency responses and time domain responses of the developed model, a conventional PID controller is designed And it is implemented using a DSP(TMS320C32) chip with precision A/D and D/A converters. Through frequency response and experimental results, it is convinced that the proposed control system works well in real environment. Furthermore it is very easy to be connected to any PC because of USB communication port, and the cost of the marking system can be lowered very much because the DSP do the all the jobs for generating font motion as well as controlling the galvanometer.