• Journal of Magnetics
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• v.1 no.1
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• pp.24-30
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• 1996

The relationship between effective permeability and the remanence ratio of an Fe-based amorphous alloy (Metglas 2605S3A) is investigated over a wide frequency range, in an effort to understand magnetization behavior of the alloy. In the frequency range from 1 to 200 kHz, the permeability is maximum at the remanence ratio of 0.4-0.5 and, at frequencies over 500 kHz, the correlation with negative coefficients emerges indicating that the permeability decreases with the remanent ratio, except for the ribbon coated with an insulating layer of MgO which exhibits both high values of the effective permeability and remanence ratio. It is considered from the correlation results that the boundary at which the dominant magnetization mechanism changes from domain wall motion to spin rotation is near 500 kHz. The core loss is also investigated as a function of annealing time when the samples are annealed at a fixed temperature of $435^{\circ}C$. The core loss in most cases decreases with the annealing time, the degree of the loss may consist of the hysteresis loss and anomalous eddy current loss. The two loss components are considered to be of similar magnitudes at low frequencies while, at high frequencies, the dominant contribution to the total loss is the anomalous loss.

• Plant Resources
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• v.3 no.3
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• pp.163-172
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• 2000

We compared microstructural features of the ordered cell and disordered leaves in Citrus junos Sieb. by electron microscopy. In the cell of the ordered leaves, many chloroplasts and large vacuoles were particularly observed. Also a lot of vessel, companion cell and big nucleus were presented in vascular bundle regions. The mitochondria and the other organelles were interspersed among the chloroplasts in a thin, peripheral layer of cytoplasm. The chloroplast possessed typical grana and intergranal lamellae, numerous starch grains and a few small osmophilic globules. Besides, microbodies were closely associated with the mitochondria and the chloroplast. The process of the formation of the secondary cell wall from primary cell wall was observed the vessel elements, the tonoplast wall and the secondary cell wall. It was observed that the oil sac with the unique perfume distributed the adjacent cell wall. In the cell of disordered leaves, the all of the organelles were thrust toward the cell wall due to the fusion of vacuoles in the cells. It was observed that a lot of the very small particles spreaded in the cytoplasm. The loss of unique perfume of the leaves was resulted in the destruction of the oil sac. Also, there was not observed grana, lamellae, starch and osmophillic globules in the chloroplast. The small distributed organelles was not observed but the elongation of the cell wall was proceed no longer. Therefore, the plasma membrane diverged from the cell wall. All of organelles in the cell had poor function and deformation. A massive vacuole was fulfilled in single cell and the vacuole contains a lot of large and small particles. The organelles were presented on the side of the cell wall according to the enlargement of vacuole and they were observed to be breakdown.

• Korea-Australia Rheology Journal
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• v.16 no.2
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• pp.75-83
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• 2004

The purpose of the present study is to investigate fluid mechanical interactions between two major abdominal aortic branches under both steady and pulsatile flow conditions. Two model branching systems are considered: two branches emerging off the same side of the aorta (model 1) and two branches emerging off the opposite sides of the aorta (model 2). At higher Reynolds numbers, the velocity profiles within the branches in model 1 are M-shaped due to the strong skewness, while the loss of momentum in model 2 due to turning effects at the first branch leads to the absence of a reversed flow region at the entrance of the second branch. The wall shear stresses are considerably higher along the anterior wall of the abdominal aorta than along the posterior wall, opposite the celiac-superior mesenteric arteries. The wall shear stresses are higher in the immediate vicinity of the daughter branches. The peak wall shear stress in model 2 is considerably lower than that in the model 1. Although quantitative comparisons of our results with the physiological data have not been possible, our results provide useful information for the localization of early atherosclerotic lesions.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.608-613
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• 2009

According to the building regulation U-value limitation of window is $3.3W/m^2{\cdot}K$ in southern regions, while U-value limitation of wall is $0.35{\sim}0.58W/m^2{\cdot}K$. It means that the energy loss through windows is five times more than it through wall. Therefore, this study analyze how much it has affected building energy rating when the insulation performance of windows and walls is changed by building regulation. In conclusion, in order to obtain 2 rating thermal performance of windows is improved more than 10 percent of U-value limitation and it of wall is improved more than 20 percent. The thermal performance of windows is improved more than 20 percent of U-value limitation and it of wall is improved more than 30 percent to receive 1 rating.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.51-54
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• 2011

In this study, It has the purpose to evaluate the insulation of the curtain wall of a building on the construction from 1990 to 2011 by measuring the inside and outside surface temperature of the curtain wall. The outside frame surface(mullion bar or spandrel bar) temperature of the curtain wall is 6℃~10℃ higher than that of the surface of glasses or insulation panel of curtain wall in winter. Furthermore the outside surface of frame anchor unit is 2℃~3℃ higher than section of other frame, so it was verified lossing lots of heating.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.4
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• pp.550-560
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• 1996

Recently, fluidized bed heat exchangers with circulating liquid are widely used in a number of places-chemical, process, food concentration, waste water treatment facilities, etc. In a circulating heat exchanger, solid particles circulate with the liquid, thereby increase the heat transfer and reduce the fouling potential of the heat exchanger. In this study, glass beads were circulated through a vertical tube. The pressure loss and the heat transfer coefficient were measured. At low flow velocities, glass beads enhanced the heat transfer considerably. The enhancement increased as the volume fraction of the glass beads increased. The pressure loss showed a similar trend. From the observed particle behavior near tube wall, a possible explanation of the trend is provided.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.56-60
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• 2007

Nowadays shear wall structural system is gradually changing to framed structure. For this reason, lightweight panel is increasingly being used as separating walls. One of design methods to obtain high transmission loss is double panel. To predict the acoustic performance of double panel, prediction of transmission loss of single panel must be performed, previously. In this study, the predicted values for four single panels were compared with the measured values. The result shows the arithmetical average deviations(100Hz to 3150Hz) between the predicted and measured transmission loss were in range between 1.1dB and 3.9dB. The predicted values were generally lower than measured values above critical frequency. The single-number quantities, $R_W+C$, were predicted in range between 36dB to 38dB, and the differences of single-number quantities between the predicted and measured value were within 1dB.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.778-782
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• 2004

Floating floor structure, which is mainly adopted for reducing interior noise of railway vehicle, is known that it is superior to single wall in respect of sound transmission loss. The dynamic characteristic of the support in the floating floor that is one of the important design variables in floating floor structure can change the sound and vibration insulation properties of it. From excitation test, the dynamic stiffness and loss factor of the support are evaluated. They are used as input parameter for analyzing the sound transmission loss of floating floor. Predicted transmission loss is compared with the prototype-car test results.

• Journal of KSNVE
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• v.8 no.5
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• pp.807-813
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• 1998

Transmission loss of the simple expansion chamber with multiple inlet and outlet ports is obtained. Transfer matrices which represent the relation between the power variables(pressure and velocity) of inlets and outlets depend on the input relatons as well as the acoustic system parameters(i.e. geometry of the chamber, wall admittance, etc.). The analysis has been performed analytically, including the effects of higher order modes for the 2-inlet/1-outlet, 1-inlet/2-outlet and 2-inlet/2-outlet systems. This study yeilds that phase difference between the inlet ports can significantly increase the transmission loss in low frequency range.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.231-235
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• 2002

A theoretical and experimental study on the combustion process in a constant volume micro combustor is described. Unlike in a macro scale constant volume combustor, the heat loss to the wall plays a major role in flame propagation in a micro micro combustor. In order to analyze the effect of heat loss on combustion phenomena, pressure transition from ignition was measured. A number of cylindrical micro combustors with different diameter and depth were used for experiment to study the effect of length scales and shape factor. The diameter of combustor ranged from 7.5mm to 22.5 mm and the height of cylinder was from 1mm to 4mm. Initial pressure was also varied for the experiment. The diagnostic methods were severely limited due to the size of the apparatus and uncertainties of certain quantities to be measured in a small-scale environment. An analytical method to derive physical quantities that are essential for performance prediction from the pressure measurements is described.