• Journal of the Architectural Institute of Korea Planning & Design
• /
• v.35 no.8
• /
• pp.65-72
• /
• 2019

The purpose of this study was to explore the influence of the topography and the neighborhood facility on the aged people's social network formation. The paper samples the aged people living in Changchun city located in a flat ground and Tonghua city located in a mountain region. Four selections of dwelling districts from the two cities are based on amount of the facilities maintaining the wealth and living area same to do the questionnaires. One hundred aged people are selected in the each dwelling district to fill out the questionnaires, and 386 valid questionnaires are finally obtained. The data obtained from the questionnaires are used to do some statistic analysis by using SPSS24.0 program. The results are shown as following: In the case of same amount of neighborhood facility for dwelling district, the aged people living in a flat ground use the facility more frequently and communicate more often with their friends and neighbors than the aged people living in a mountain region do, the social network forms more easily as well. In the other case of same topography dwelling districts, the aged people living in an abundant facility dwelling district use the facility more frequently and communicate more with their neighbors and friends than the aged people living in a mountain region do, so the social network forms more easily as well. Thus it can be seen that topography and amount of facility are significant influence factors of the aged social network formation.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.30 no.2
• /
• pp.109-115
• /
• 1994

This paper presents a new concept to reduce turbulent frictional drag by injecting micro-bubble into near the buffer layer of turbulent boundary layer on flat plate. The concentrations of micro bubble distribution in the boundary was calculater by eddy viscosity equations in the governing equations. When near region of the buffer layer of turbulent boundary layer is filled with micro-bulle of air and viscous of the region is kept low, the velocity profile in the near region should be changed substantially. Then the Reynolds stress in the region becomes less, which guide to lower velocity gradient there. It results in reduction of velocity gradient at the viscous sublayer, which gives the reduction of shear stress at the wall.

• Journal of Fisheries and Marine Sciences Education
• /
• v.5 no.2
• /
• pp.128-137
• /
• 1993

This paper presents a new concept to reduce turbulent frictional drag by injecting micro-bubble into buffer layer of turbulent boundary layer on flat plate. The buffer layer of boundary was specified by minus velocity gradient of law of the wall. When the buffer layer region of turbulent boundary layer is filled with micro-bubble of air and viscous of the region is kept low, the velocity profile in the region should be changed substantially. Then the Reynolds stress in the buffer layer region becomes less, which guide to higher velocity gradient there. It results in reduction of velocity gradient at the viscous sublayer, which gives the reduction of shear stress at the wall.

• Journal of Ocean Engineering and Technology
• /
• v.28 no.4
• /
• pp.268-273
• /
• 2014

To investigate the turbulence characteristics within the boundary layer over a flat plate, an experimental study was performed using a PIV technique in a circular water channel. For two water velocities, 0.92 and 1.99 m/s, the water velocity profiles were taken and analyzed to determine turbulent characteristics such as the Reynolds stress, Taylor micro-length scale, and Kolmogorov length scale within the defect law region of the boundary layer. These analysis methods may be applied to research on the friction drag reduction technology using micro-bubbles or an air sheet over the surface of a ship's hull, because the physical reason for the friction drag reduction could be found by understanding the variation of the turbulence characteristics and structures in the boundary layer.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.15 no.6 s.99
• /
• pp.687-696
• /
• 2005

Acoustic power spectrum of the upstream and downstream sound field due to an isotropic frozen turbulent gust impinging on a cascade of flat plate airfoils are computed by using a analytic formulation derived from Smith's method, and Whitehead's LINSUB codes. A parametric study of the effects on sound power of the number of blades and turbulence length scale is performed with an emphasis on analyzing the characteristics of sound power spectrum. Through the comparison of the computed results of sound power, it is found that acoustic power spectrum from the 2-D cascade subject to a ingested turbulence can be categorized into two distinct regions. one is lower frequency region where some spectral components of turbulence do not contribute to the cut-on acoustic modes and therefore the effect of the cascade geometry is more dominant ; the other is higher frequency region where all of spectral components of turbulence make contributions to cut-on acoustic modes and thus acoustic power is approximately proportional to the blade number.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.9
• /
• pp.1733-1740
• /
• 2011

In this research, a MEMS vibratory gyroscope with dual-mass system in the sensing mode has been proposed to increase the stability of the device using wide bandwidth. A wide flat region between the two resonance peaks of the dual-mass system removes the need for a frequency matching typically required for single mass vibratory gyroscopes. Bandwidth, mass ratio, spring constant, and frequency response of the dual-mass system have been analyzed with MATLAB and ANSYS simulation. Designed first and second peaks of sensing mode are 5,917 and 8,210Hz, respectively. Driving mode resonance frequency of 7,180Hz was located in the flat region between the two resonance peaks of the sensing mode. The device is fabricated with anodically bonded silicon-on-glass substrate. The chip size is 6mm x 6mm and the thickness of the silicon device layer is $50{\mu}m$. Despite the driving mode resonance frequency decrease of 2.8kHz and frequency shift of 176Hz from the sensing mode due to fabrication imperfections, measured driving frequency was located within the bandwidth of sensing part, which validates the utilized dual-mass concept. Measured bandwidth was 768Hz. Sensitivity calculated with measured displacement of driving and sensing parts was 22.4aF/deg/sec. Measured slope of the sensing point was 0.008dB/Hz.

• ALGAE
• /
• v.17 no.3
• /
• pp.135-144
• /
• 2002

Scytosiphonaceae is an acetocarpalean brown algal family, that is a recent focus of synstematics and marine biodiversity. We describe Petalonia zosterifolia and Scytosiphon gracilis from Korea for the first time. P. zosterifolia occurred on the East coast, and had flat, linear and solid thalli. S. gracilis was found in Jeju, and had cylindircal to flat and hol-low thalli. However, these two species are so similar that it is difficult to identify by morphology alone. In order to determine if the nuclear DNA reveals the distinctness of both species and to know their phylogenies, the ITS region sequences were newly detrmined in 22 samples of P. zosterifolia, Scytosiphon gracilis, and other three members of the genera from Korea. We found 0.12% variation among samples of P. zosterifolia from different locations, and no variation between S. gracilis samples from diferent years, but extensive interspecific divergences (13.62-22.83%) of each species to other members in Petalonia and Scytosiphon . The ITS sequence dta consistently showed a close relationship between P. zosterifolia and S. gracilis. This result is congruent with morphology and with the published data of plastid rbc and partial nrDNA large subunit gene sequences, and suggests that P. zosterifolia and S. gracilis might have diverged from the most recent common ancestor.

• Journal of Mechanical Science and Technology
• /
• v.16 no.7
• /
• pp.966-974
• /
• 2002

An analytic approach has been employed to study condensate film thickness distribution inside cave-shaped cavity of a flat plate heat pipe. The results indicate that the condensate film thickness largely depends on mass flow rate and local velocity of condensate. The increasing rate of condensate film for circular region reveals about 50% higher value than that of vertical region. The physical properties of working fluid affect significantly the condensate film thickness, such as the condensate film thickness for the case of FC-40 are 5 times larger than that of water. In comparison with condensation on a vertical wall, the average heat transfer coefficient in the cave-shaped cavity presented 10∼15% lower values due to the fact that the average film thickness formed inside the cave-shaped cavity was larger than that of the vertical wall with an equivalent flow length. A correlation formula which is based on the condensate film analysis for the cave-shaped cavity to predict average heat transfer coefficient is presented. Also, the critical minimum fill charge ratio of working fluid based on condensate film analysis has been predicted, and the minimum fill charge ratios for FC-40 and water are about Ψ$\_$crit/=3∼7%, Ψ$\_$crit/=0.5∼1.3% respectively, in the range of heat flux q"=5∼90kW/㎡.

• Journal of Korea Multimedia Society
• /
• v.2 no.3
• /
• pp.320-328
• /
• 1999

The Laplacian operator is usually used as a regularization operator which may be used as any differential operator in the regularization iterative restoration. In this paper, several kinds of differential operator and 1-H operator that has been used in our lab as well, as a regularization operator, were compared with each other. In the restoration of noisy motion-blurred images, 1-H operator worked better than Laplacian operator in flat region, but in the edge the Laplacian operator operated better. For noisy gaussian-blurred image, 1-H operator worked better in the edge, while in flat region the Laplacian operator resulted better. In regularization, smoothing the noise and resorting the edges should be considered at the same time, so the regions divided into the flat, the middle, and the detailed, which were processed in separate and compared their MSE. Laplacian and 1-H operator showed to be suitable as the regularization operator, while the other differential operators appeared to be diverged as iterations proceeded.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.14 no.6
• /
• pp.1197-1206
• /
• 2019

Suncheon Bay is a very important natural resource and various efforts have been made to protect it from the environmental pollution. Although the project to monitor the environmental changes in periodically by observing the creatures in tidal flats is processing, it is being done inefficiently by people directly observing it. In this paper, we propose an object segmentation method that can be applied to the method to automatically monitor the living creatures in the tidal flats. In the proposed method, a foreground map representing the location of objects is obtained by using a temporal difference method, and a superpixel method is applied to detect the detailed boundary of an image. Finally the region of crab is extracted by combining the foreground map and the superpixel information. Experimental results show that the proposed method separates crab regions from a tidal flat image easily and accurately.