• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.4
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• pp.332-338
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• 2014

Experimental study is conducted for investigating the characteristics of friction-induced noise with respect to the variation of system geometry. In this study, a vertically fixed rod is in contact with the reciprocating plate which is controlled by the step motor. Friction noise is generated during the reciprocating motion due to the frictional contact between the plastic pin and the aluminum plate. The frequencies of the friction noise are changed when the height of the rod varies. However, it is found that the vibration modes involved in the friction noise are not changed. It implies that the unstable modes remain unstable regardless of the change of the system geometry, and thus, there are the certain mode shapes which are likely to produce friction noise.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.2
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• pp.9-15
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• 2014

'Visual segment surface' means a surface that extends from the missed approach point of non precision approaches (or the decision altitude location for approaches with vertical guidance and precision approaches) to the threshold to facilitate the identification of and protection from obstacles in this visual segment of the approach. Validation is the necessary final quality assurance step in the procedure design process, prior to publication. The purpose of validation is the verification of all obstacle and navigation data, and assessment of flyability of the procedure. This paper shows how to apply the protection for the visual segment of the approach procedure, and the results of the validation for visual segment surface conducted at an airport.

• Journal of the Optical Society of Korea
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• v.15 no.4
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• pp.352-356
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• 2011

Dual-wavelength holography has a better axial range than single-wavelength holography, allowing unambiguous phase imaging. Partial coherence sources reduce coherent noise, resulting in improved reconstructed images. We measured a ball-grid array using dual-wavelength holography with partial coherence sources. This holography method is useful for measurement samples that exhibit coherence noise and have a step height larger than the single wavelength used in holography.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1364-1367
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• 1996

Recently, direct rolling process, called as strip casting process, has been interested in to save production cost by reducing forming processes. In direct rolling process, since a steel strip of thickness 1-5(mm) can be produced directly from molten metal, it can eliminate secondary hot rolling process. On the other hand, since many process variables are existed in this process and relation of these variables is very complex, it is difficult to realize the process design and the quality control. In this paper, as first step to overcome above difficulties, the quantitative relationship of the process variables affected to quality of the strip has been carried out through the numerical analysis. Also, we determined the process variable to monitor the quality in the direct rolling process. As a result, we show that the solidification final point, called as Nip point, was related directly to quality of the strip.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.11
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• pp.1044-1051
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• 2004

This paper described a novel locomotion interface that can generate infinite floor for various surface, named as virtual walking machine. This interface allows users to participate in a life-like walking experience in virtual environments, which include various terrains such as plains, slopes and stair ground surfaces. The interface is composed of two three-DOF (X, Y, Yaw) planar devices and two four-DOF (Pitch, Roll, Z, and relative rotation) footpads. The planar devices are driven by AC servomotors for generating fast motions, while the footpad devices are driven by pneumatic actuators for continuous support of human weight. To simulate natural human walking, the locomotion interface design specification are acquired based on gait analysis and each mechanism is optimally designed and manufactured to satisfy the given requirements. The designed locomotion interface allows natural walking(step: 0.8m, height: 20cm, load capability: 100kg, slope:30deg) for various terrains.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.4
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• pp.166-169
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• 2001

6H-SiC bulk crystals were grown by sublimation method with different conditions in term of gaseous pressures ad source temperatures. In order to optimize the growth rate, pressure at growth period and source and substrate temperatures were investigated as experimental variables. the results were compared with each other and finally the optimum growth conditions were discussed. Furthermore the relation of the growth steps and defects formation was evaluates in the point of reducing the micropipes. Subsequently the growth steps and defects formation was evaluated in the point of reducing the micropipes. Subsequently the growth steps were observed leading to the lower step height with the lower growth rate.

• Journal of Environmental Science International
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• v.21 no.6
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• pp.661-666
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• 2012

This article reveals the relationship between the body characteristics of the elder people and the size of park facilities during utilization of parks by scientific investigation. The experiment involves 540 elder people, and offer concrete evidence for park design in ageing society. These evidences mainly consists of the following aspects: First, the relation between physical situation of elder people and their using parks. Secondly, the relation between the hearing status and exchange circle diameter in elders. The last is the relation between the distance visual acuity and designing the scene. Finally we get the most suitable step length range, stairs height, road slope, communication space diameter and general formulas about the best vision distance for elder people.

• Publications of The Korean Astronomical Society
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• v.13 no.1 s.14
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• pp.17-30
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• 1998

To study kinematics of solar prominences, we have made Ha spectrographic study of an eruptive prominence which appeared on the 27th of August, 1992 with a position angle of 270 deg. The observation was carried out by a Littrow type spectrograph and a G1 CCD camera attached to the 25cm coronagraph at Norikura Coronal Station. In taking the spectral data the slit was placed in parallel to the solar limb at 7 different heights, each being separated by 5 arcsec with a time step of 30 sec. The observed eruptive prominence shows a wide range of line of sight Doppler velocity, spanning from $V_{dopp}=-17.5km/s\;to\;V_{dopp}=58.2km/s$. It is also found that the velocity increases with height at the rate of ${\Delta}V= 0.86 km/s/arcsec$.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.521-524
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• 2003

In this paper, we propose a face region extraction algorithm using color information and projection. After the extraction of face candidate image using adaptive color information, we project it into vertical direction to estimate the width of the face. Then the redundant parts of the face are efficiently removed by using the estimated face width. And the width information of the face is used at the horizontal projection step to extract the height of the face, and non-face region such as the neck and some background regions, which are represented as the similar skin color, effectively eliminated. From the experiment results for the various images, the proposed algorithm shows more accurate results than the conventional algorithm.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.84-85
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• 2003

A parallelized FEM code based on domain decomposition method has been recently developed for a large scale computational fluid dynamics. A 4-step splitting finite element algorithm is adopted for unsteady computation of the incompressible Navier-Stokes equation, and Smagorinsky LES(Large Eddy Simulation) model is chosen for turbulent flow computation. Both METIS and MPI library are used for domain partitioning and data communication between processors respectively. Tiburon of Hyundai-motor is chosen as the computational model at $Re=7.5{\times}10^{5}$, which is based on the car height. It is confirmed that the drag under road condition is smaller than that of wind tunnel condition.