• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.398-403
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• 2004

The demand of high speed machining is increasing because the high speed cutting providers high efficiency of process, short process time, improved metal removal capacity and better surface finish. Active magnetic bearings allow much high surface speed than conventional ball bearings and therefore greatly suitable for high speed cutting. The automatic control concept of magnetic bearing system provides ability of intelligent control of spindle system to increase accuracy and flexibility by means of adaptive vibration control. This paper describes a design and development of a milling spindle system which includes built-in motor with power 5.5㎾ and maximum speed 70,000rpm, HSK-32C tool holer and active magnetic bearing system. Magnetic actuators are designed for satisfying static load condition. The Performances of manufactured spindle system was examined for its static and dynamic stiffness, load capacity, and rotational accuracy. This spindle was run up to 70,000 rpm stably, which is 3.5 million DmN.

• Korean Journal of Digital Imaging in Medicine
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• v.12 no.1
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• pp.15-18
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• 2010

Main component of radiography barrier aprons is lead. To manufacture a lead-free barrier sheath, barium sulfate and organic iodine-based chemicals should be mixed with rubber. Barrier capacity was tested in the medical field. To improve adaptation of rubber with the mixture, raw materials went through milling, agitation, and extruding processes. Three sheaths were manufactured with 30%, 80%, and 120% sulfate barium, respectively. This study found 10% lower barrier capacity of lead-free barrier than the traditional lead-containing rubber sheath. Problems, however, were confronted during the agitation and extruding processes. Mixing with rubber was a technically demanding job. Inconsistent depth, problems with thermal processing and dissipation were encountered as well.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.7
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• pp.1335-1345
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• 1994

In this paper, the performance analysis of Inter-Processor Communication Network(IPCN) in a large-capacity digital switching system, TDX-10, is presented. The simulation model of IPCN is developed using discrete event model of SLAM II. The simulation results of maximum buffer length and mean waiting times at each node, and utilization of D-bus are derived. Finally, the maximum call handling capacity of IPCN is obtained by taking link speed into consideration.

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.75-80
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• 2017

Nowadays, smart phone is being popularly used for communication, entertainment, and information retrieval. While demands on video traffic over mobile networks increases sharply, the wireless link capacity is often limited to fully support the traffic demand. Therefore, the size of video data needs to be reduced to provide high quality video with limited capacity. To handle this issue, we propose a video editing system using the ffmpeg library. The proposed system can provide a high quality video with a relatively small data size, thereby facilitating the mobile streaming services and live-video games.

• The Transactions of the Korean Institute of Power Electronics
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• v.1 no.1
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• pp.7-11
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• 1996

From the cost-effective point of view, it is very important to design a current with the highest utilization factor of current capacity of power devices. This can be accomplished by a current controller without overshoot irrespective of the varying bounds of control voltage in PWM converters and the dead time due to the time delay. This paper suggests a novel decoupled controller with Smith-Predictor which has the fast control response without overshoot and steady stats error and also deal with the design method of the controller for PWM converters. The extensive digital simulations done by SIMULINK/MATLAB show that the suggested controller guarantees the full utilization of current capacity of power devices and the decoupled current control behavior.

• International Journal of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.11-16
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• 2024

Illegal manipulation and alteration of digital content are becoming a social issue. To address this problem, there is an increasing demand for the development of technologies to prevent the manipulation and alteration of digital content. This paper proposes a data hiding algorithm capable of embedding a larger amount of confidential data in the original cover image while minimizing the degradation of image quality in stego images. The algorithm presented in this paper analyzes the characteristics of the image to extract corner points and then uses a method to insert watermarks around these extracted corner points. Additionally, through experimentation, it has been proven that this algorithm can insert a greater amount of watermark without degrading the image quality compared to other existing algorithms.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1232-1238
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• 2009

As power facilities are getting higher at capacity, the monitoring and diagnosis of generators for fault detection and protection has attracted intensive interest. In case of an after-fault in high capacity rotating machines, the recovering cost is usually very expensive and additional time is necessary for returning in a normal situation. In this paper, we developed the protection program for the generator fault protection system and each module of the digital protective relay H/W for loading the protection program. The protective relay H/W was designed to have EMC characteristics for prohibiting from fault operation in bad power systems.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.47-52
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• 2005

A lot of information storage devices have been introduced and developed for recently years. The trends of those devices are high capacity, compact size, low power consumption, reliability, and removability for data interchange with other device. As a satisfaction of these trends, near-field technique is in the spotlight as the next generation device. In order for a near-field recording to be successfully implemented in the storage device, a slider and suspension is introduced as actuating mechanism. The optical slider is designed considering near-filed optics. Suspension is not only supports slider performance, and tracking servo capacity but also meets the optical characteristics such as tilt aberration, and guarantee to satisfy shock performances for the mobility fir the actuator. In this study, the optical slider and the suspension for near-field probe array are designed and analyzed considering dynamic performance of head-gimbal assembly and shock simulation..

• 한국ITS학회:학술대회논문집
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• 2010.05a
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• pp.1-4
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• 2010

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.199-204
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• 2003

Digital high resolution cameras are widely available, and are increasingly use in digital close-range photogrammetry. And photogrammetry instruments are developing rapidly and the precision is improving continuously, The building of 3D terrains of high precision are possible and the calculation of the areas or the earthwork volumes have high precision due to the development of the technique of the spatial information system using computer, In this study, using the digital camera which has capacity of keeping numerical value by itself and easy carrying, we analyze the positioning error according to various change of photographing condition. Also we t]v to find a effective method of acquiring basis data for 3D monitoring of high-accuracy in pixel degree through digital close-range photogrammetry with bundle adjustment for local terrain model generation and earthwork volume.