• Transactions of the KSME C: Technology and Education
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• v.1 no.2
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• pp.193-198
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• 2013

The horseback riding simulator, an exercise training machine providing a simplified horse riding motion has been developed for aiming at healthcare. The purpose of this study was to estimate the energy expenditure without measuring bio-signals using the simulator. The test protocol was consisted of increase up to maximal intensity(Motion 9) and decrease down to minimal intensity(Motion 4) during 25 minutes, and energy expenditure was measured by portable cardiopulmonary exercise testing analyzer. There were significant differences in energy expenditure according to each riding motion. The result will be able to estimate energy expenditure using motion level, exercise time, age and gender during the riding.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.1
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• pp.89-94
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• 2006

Traditionally fatty acid composition used to be analysed by a GC and the sample preparation process includes lipid extraction from sample and subsequent methyl esters preparation, which are time-consuming and cumbersome. As an alternative, simultaneous extraction/methylation methods are being developed for rapid and simplified sample preparation. To optimize one-step extraction/methylation method for analysis of fatty acid composition in brown rice, various reaction factors such as sample to reaction solution ratio, reaction time and temperature, shaking intensity were changed and resultant fatty acid composition data were evaluated in comparison with previous reports. The ratio of sample weight to reaction solution volume was the most critical factor in that higher sample to reaction solution ratio caused overestimation of palmitic acid and linoleic acid composition, resulting in underestimation of oleic acid. Lower reaction temperature also induced overestimation of linoleic acid and underestimation of oleic acid. Reaction duration and the intensity of shaking prior to and during the reaction, however, caused no significant changes in analysis results. In conclusion, the optimum condition was mixing 5 grains (about 0.2 g) of brown rice with $680{\mu}L$ of extraction/methylation mixture and $400{\mu}L$ of heptane, followed by reaction at $80^{\circ}C$ for 2 hours.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.997-1002
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• 2013

The article is aiming to investigate the thermal-fluidic characteristics of magnetic fluid in a cavity using GSMAC (generalized-simplified marker and cell method). The transport equations of the magnetic fluid are including the continuity equation, momentum equation and energy equation for natural convection and Maxwell equation and magnetization equation of magnetite nano-sized particles motion. In addition, the heat transfer characteristics such as temperatures and Nusselt numbers and flow characteristics such as streamlines and isotherms of the magnetic fluid were analyzed with the intensity and direction of the magnetic fields. As a result, the thermal-fluidic characteristics of the magnetic fluid in a cavity were could be controlled by the intensity and direction of the magnetic fields.

• Smart Media Journal
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• v.2 no.2
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• pp.28-32
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• 2013

In this paper, we present a method to reduce complexity of depth modeling modes (DMM) that are used in the current 3D-HEVC standardization. DMM adds four modes to the existing HEVC intra prediction modes for accurate object edge representation in the depth map. Especially, Mode 3 requires distortion calculation of numerous pre-defined wedgelets, inducing high complexity. The proposed method employs absolute differences of neighboring pixels in the sides of the reference block to find high intensity changing positions. Based on such positions, the number of wedgelet candidates is reduced to six and distortion calculation is skipped for irrelevant wedgelets. Experimental results show complexity reduction by 3.1% on average, while maintaining similar coding performance.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.42-50
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• 2002

The duration and H/V ratio(the amplitude ratio of the horizontal to vertical components) of ground motions caused by earthquakes in southern Korea are analyzed. Total 329 seismograms of horizontal component recorded at hypocentral distances of 10 to 350 km from 27 earthquakes with local magnitude 2 to 4 are used for the analysis. Simplified relation between the duration of ground motion( $T_{d}$) and the ratio($\chi$) of Arias intensity( $I_{A}$) and squared maximum acceleration($\alpha$$_{max}$$^{2}$) is determined to be $T_{d}$ = 3.423$\chi$$^2$+ 8.200$\chi$ + 0.029, which is useful for the estimation of the duration in southern Korea. There are three distinct distance ranges with different linear variations of the duration in hypocentral distance. They are distance intervals of 10~80km, 80~140km, and the distance greater than 140km. The duration in southern Korea shows clear proportionality to the local magnitude at magnitudes greater than 3.1. The value 1.37 of the H/V ratio obtained in southern Korea is similar to the value 1.4 of ENA(Eastern North America). The H/V ratio in southern Korea increases in the frequency range from 0.3 to 10Hz. The duration and H/V ratio of ground motions derived in this study could be used in the stochastic simulation of strong ground motion.ion.n.n.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.711-714
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• 2002

At the lift-off condition, the combustion and Jet noise of launch vehicle produces a severe acoustic environment and the acoustic loads may be damaging to paylaod and equipments. Prediction of the acoustic environment is thus needed to support the load-resistive design and test-qualification of components. Currently, such a high frequency problem is usually dealt with by using the SEA technique, for which the assumptions should match reasonably well with the vibro-acoustic condition of system. The subsystems of SEA model was composed of 16 flat plates, 8 L-shaped beams, and 2 acoustic cavities. The frequency range was 400 Hz - 4 kHz considering the modal parameter. The experiment was performed in a high intensity acoustic chamber, in which the diffuse acoustic field was assured. By comparing the SEA analysis and the experiments, the error less than 5 dB was observed.

• Geomechanics and Engineering
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• v.22 no.1
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• pp.25-33
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• 2020

In metropolitan areas, the quantity and density of the underground structure increase rapidly in recent years. Even though most damage incidents of the underground structure were minor, there were still few incidents causing a great loss in lives and economy. Therefore, the safety evaluation of the underground structure becomes an important issue in the disaster prevention plan. Liquefaction induced uplift is one important factor damaging the underground structure. In order to perform a preliminary evaluation on the safety of the underground structure, simplified prediction equations were introduced to provide a first order estimation of the liquefaction induced uplift. From previous studies, the input motion is a major factor affecting the magnitude of the uplift. However, effects of the input motion were not studied and included in these equations in an appropriate and rational manner. In this article, a numerical simulation approach (FLAC program with UBCSAND model) is adopted to study effects of the input motion on the uplift. Numerical results show that the uplift and the Arias Intensity (Ia) are closely related. A simple modification procedure to include the input motion effects in the Sasaki and Tamura prediction equation is proposed in this article for engineering practices.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.3
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• pp.230-236
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• 2016

This research attempted simplifications to the LED street light for price competitiveness. The street light was simplified by replacing the SMPS with an IC driver on the PCB using an AC-type LED. The optical element that shape of a line-shaped lens covered LED crowded. Thus, this study aims to improve LED efficiency by using the minimum optical system. In order to satisfy the M3 regulation of street lighting at grade, the lens was divided into two parts depending on the forward direction of the light. Further, the changes in the number of LEDs located on part 1 and part 2 of the lens were analyzed. Through simulation, we determined the proper light distribution that meets M3 regulation of street lighting.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.536-540
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• 2003

A new concept of adaptive focusing, using a Rotman lens, is presented in this paper. A Rotman lens is a microwave lens which is able to focus microwave power on its focal arc or generate multiple beams. By adding the array of phase shifters between a Rotman lens and antenna elements, the wavefront can be adaptively modulated to focus objects distributed in short range rather than far-field zone. From the optical point of view, the propagations of the lens have been simplified from the Fresnel diffraction integral to the Fourier transform. Using Fourier Transform, a beam propagation method has been developed to show improvement of the resolution by controlling wavefront of wave propagating from an aperture-type antenna array. The beam width(or spot size) and intensity have been calculated for a focused beam propagating from an array having $10{\lambda}$ of its size. For the beam with $20{\lambda},\;30{\lambda}$, and $50{\lambda}$ of geometrical focal length, the half-power beamwidth (spot size) is about $1.1{\lambda},\;1.3{\lambda}$, and $1.9{\lambda}$, respectively.

• Coupled systems mechanics
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• v.5 no.2
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• pp.101-126
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• 2016

Seismic structural fragility constitutes an important step for performance based seismic design. Lateral load-resisting structural members are often analyzed under one component base excitation, while the effect of bi-directional shaking is accounted per simplified rules. Fragility curves are constructed herein under real bi-directional excitation by a simple extension of the conventional Incremental Dynamic Analysis (IDA) under uni-directional shaking. Simple SODF systems, parametrically adjusted to different periods, are examined under a set of near-fault and far-fault excitations. Consideration of bi-directional interaction appears important for stiff systems. Further, the study indicates that the peak ground accelertaion, velocity and displacement (PGA, PGV and PGD) of accelerogram are relatively stable and efficient intensity measures for short, medium and long period systems respectively. '30%' combination rule seems to reasonably predict the fragility under bi-directional shaking at least for first mode dominated systems dealt herein up to a limit state of damage control.