• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.2
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• pp.199-206
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• 2016

Linear motion (LM) ball guides with rolling contact are core units of feed-drive systems. They are widely applied for precision machinery such as machine tools, semiconductor fabrication machines and robots. However, the friction force induced from LM ball guides generates heat, which deteriorates positioning accuracy and incurs changes of stiffness and preload. To accurately analyze the effects and apply the results to precision machine design, mathematical modeling of the friction force is required. In this paper, accurate formulation of the friction force due to rolling, viscous, and slip frictions is conducted for LM ball guides. To verify the reliability of the developed friction model, experiments are performed under various assembly, load and velocity conditions. Effects of frictional components are analyzed through the formulated friction model.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.2
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• pp.24-30
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• 2009

In this paper, the FPGA modem platform complying with 3GPP Release 7 eHSPA specifications and its regularized verification flow are proposed. The FFGA platform consists of modem board supporting physical layer requirements, MCU and DSP core embedded control board to drive the modem board, and peripheral boards for RF interfacing and various equipment interfaces. On the other hand, the proposed verification flow has been regularized into three categories according to the correlation degrees of hardware-software inter-operation, such as simple function test, scenario test call processing and system-level performance test. When it comes to real implementations, the emulation verification strategy for low power mobile SoC is also introduced.

• Korean Journal of Construction Engineering and Management
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• v.6 no.2 s.24
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• pp.92-101
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• 2005

The duration of highrise building projects is more shorter than its increasing of the numbers of floors. The project is liable to overrun of the time in which the project must be complete. AS highrise buildings are increased, time management has been reorganized as critical success factor. To improve time management, time management softwares are introduced and the software's education is made lively in construction company. However a large amount of time management works still have been based on not the software but scheduler's experience. We often can find the time overrun risk of highrise building because of the shortage of scheduler's experience. To diminish the mistake of the scheduler who does not have much experience, we suggested HRB Expert which uses expert's knowledge to make the time plan of highrise building. We made an example of knowledge acquiring and knowledge usage which cased on reinforced concrete work of highrise building by literature review and interview with scheduling expert. The precision of time plan will be enhanced and time overrun will be prevented on condition that HRB Expert is constructed and used

• Korean Security Journal
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• no.21
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• pp.1-18
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• 2009

Background: This study was to investigate the effects of spinal strengthening exercise and lumbar stabilization exercise(core exercise program) on trunk muscle strength, flexibility and balance, lumbar function. The subjects of this study were the eighteen subjects who was registered in private guard company. The each exercise group of 9 persons were chosen by random controlled trial. Methods: We used instrument BTE, Libra, Ruler Measuring tape to measured trunk muscle strength, flexibility, balance and lumbar function. Results: The result of this study were summarized below; The flexor muscle strength was improve in lumbar stabilization exercise(core exercise) group(p<.05). The extensor muscle strength was improve in lumbar stabilization exercise(core program) group(p<.05). The trunk flexibility was improve in spinal strengthening exercise group and lumbar stabilization exercise group(p<.05). The balance ability was improve in spinal strengthening group and lumbar stabilization exercise group(core program) group(p<.05). Conclusion: With the above results, demonstrated effects of spinal strengthening exercise and lumbar stabilization exercise in each private guard and security in this study.

• Korean Security Journal
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• no.17
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• pp.195-220
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• 2008

Various Kinds of social pathology and crimes that threaten our daily safety are on the increase in process of time as a result of the development of science and technology empty of moral sense, Value Confusions, apolaustic tendency, economic and social transformation recently. Moreover the effective provision of police service lies beyond the boundaries of the police organization. Therefore private security personnel have made an effort for safety and protection of group as well as an individual through the introduction of private security industry based on a benefit principle and private security industry is being become complexes utilizing technology as well as high-end devices through various international events. The field of private security industry in Korea is being extended rapidly with expansionism of society and public services but the quality improvement is declining. Furthermore the study of recruit education program for security personnel as the basis of quality improvement is insufficient compared with the study of police service. Consequently, this investigation is going to contribute to development of recruit education program for security personnel through the analysis about difference of each subject usability for education about electronic security and facility guard.

• Journal of Korean Society of Steel Construction
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• v.16 no.5 s.72
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• pp.653-660
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• 2004

To increase the efficiency of the urban areas, pipe section steel piers, which have relatively small sections, must be constructed. Since smaller sections mean decreased load capacity, longitudinal stiffeners were applied to the pipe section steel piers to increase their load capacity. Increased load capacity through longitudinal stiffeners, however, could not yet be confirmed. Therefore, the effect of longitudinal stiffeners on the load capacity of pipe section steel piers still needs to be studied. In this paper, the effect of the number of longitudinal stiffeners on the load capacity of steel piers was determined by carrying out elastic plastic FE analysis on material and geometric non-linearity. In addition, comparative analyses of the parameters of the width, the thickness of longitudinal stiffeners, and the slenderness ratio of steel piers were carried out to determine the effects of longitudinal stiffeners.

• Journal of the Korean Geotechnical Society
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• v.29 no.2
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• pp.65-73
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• 2013

The purpose of this study is to confirm strength and effectiveness of grouting of the sand treated with bacteria. In order to analyze the cementation of sand treated with bacteria, five types of specimens(Not treated, Cement 2% treatment, Cement 4% treatment, Cement 2% + $CaCO_3$ 2% treatment and $CaCO_3$ 4% treatment) were made. Unconfined compressive strength tests were done on $D\;5cm{\times}H\;10cm$ specimens and biogrouting tests were performed on $D\;6cm{\times}H\;12cm$ specimens to observe the effectiveness of grouting with bacteria. As a result, Cement 2% + $CaCO_3$ 2% treatment was found to be the most effective in terms of the unconfined compressive strength.

• Journal of Biomedical Engineering Research
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• v.23 no.5
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• pp.385-390
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• 2002

Nowadays, there are many attempts to develop domestic medical-equipments. In this study, it is performed to developed a new vertebral fusion device. The basic models are a rectangular-frame type and a screw type which are generally used for the patients. The main purpose of the development of a new device is to reduce the amount of bone taken out for the insertion of a device to vertebral disc and this paper is focused on th concept of a new device shape. In the results, two types are devised. One is a folding type and the other is a separate-push-in type device both are in primitive stage. However, in a folding type there are mechanical pins and the analysis of pins and the lock system is still in study and needs some time. Therefore a separate-push-in type is introduced in this study mainly and a prototype and 3-D finite element model are made and experimented and stress analyzed. From the results it is considered that it is stable for the basic loading condition of vertebra, however, it is required to develop a supporting operational equipment for the convenience of the operation in practice.

• Journal of Broadcast Engineering
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• v.15 no.1
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• pp.76-88
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• 2010

Recently, LED background image devices are used for the production of broadcasting programs. But the effective advantages of LED background image devices are not realized for good HD video quality because the correlations between lighting sources and LED background image devices are not analyzed yet. In this paper, we analyze the color change and light intensity that lighting sources and the light intensity ratio of LED background images influence on a subject, making use of equipments used in real broadcasting, and examine the correlations between HD video quality and the light intensity ratio of LED background images. As a result in this experiment, the video is most expressed having an 20[IRE] effect on a subject when the light intensity of LED background image is 6%. When the LED background image is light, the light and darkness of video is distorted and when the LED background image is dark, the colors of image are distorted.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4276-4283
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• 2015

The purpose of this research is to identify the effectiveness of injection with soil conditions by injecting CaCO3(created by microorganism reaction), which was recreated with equipment in similar situ condition. To analyze our research, we made 2 cases of single-layer (SP, SW) in D 150mm ${\times}$ H 300mm. Layers were made by RC 70, 80, 85, 90, 95% of soil condition. We measured uniaxial compression strength with cone penetrometer and watched injection range by checking a bulb formation around the injection nozzle. As a result, the relative compaction(RC) in more 85% were not injected in SW, we could identify the effect of bio-grouting technology on ground in relative compaction(RC) of injection ratio and cementation range.