• Transactions of the Korean hydrogen and new energy society
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• v.18 no.2
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• pp.189-196
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• 2007

The evaporation heat transfer coefficient and pressure drop of $CO_2$(R-744) in a horizontal tube was investigated experimentally. The main components of the experimental apparatus are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and an evaporator(test section). The test section consists of a horizontal stainless steel tube of 4.57 mm inner diameter. The experiments were conducted at mass flux of $200{\sim}1000\;kg/m^2s$ saturation temperature of $0{\sim}20^{\circ}C$, and heat flux of $10{\sim}40\;kW/m^2$. The test results showed that the heat transfer coefficient of $CO_2$ has a greater effect on nucleate boiling more than convective boiling. Mass flux of $CO_2$ does not affect nucleate boiling too much. In comparison with test data and existing correlations, All of the existing correlations for the heat transfer coefficient underestimated the experimental data. However lung et al.'s correlation showed a good agreement with the experimental data. The evaporation pressure drop of $CO_2$ increases with increasing mass flux and decreasing saturation temperature. When comparison between the experimental pressure drop and existing correlations. Existing correlations failed to predict the evaporation pressure drop of $CO_2$.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.154-159
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• 2008

Two-phase flow boiling heat transfer of R-410A in horizontal small tubes was reported in the present experimental study. The local heat transfer coefficients were obtained over a heat flux range of 5 to 40 kW/$m^2$, a mass flux range of 170 to 600 kg/$m^2s$, a saturation temperature range of 3 to $10^{\circ}C$, and quality up to 1.0. The test section was made of stainless steel tubes with inner diameters of 0.5 and 3.0 mm, and lengths of 330 and 3000 mm, respectively. The section was heated uniformly by applying a direct electric current to the tubes. The effects on heat transfer of mass flux, heat flux, inner tube diameter, and saturation temperature were presented. The experimental heat transfer coefficient is compared with six existing heat transfer coefficient correlations. A new boiling heat transfer coefficient correlation based on the superposition model for R-410A in small tubes was developed with mean deviation of 10.13%.

• Bulletin of the Society of Naval Architects of Korea
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• v.12 no.2
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• pp.3-12
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• 1975

As for two dimensional added mass coefficients for straight framed hull forms in a free surface of an ideal fluid, theoretical calculations by F.M. Lewis, vertical, K. Wendel, J.H. Hwang, and etc. are available; vertical modes of rectangular and triangle sections by Lewis, vertical, horizontal and torsional models of rectangular and triangle section by Wendel, and systematical calculations for vertical modes of single chine forms by Hwang. In this paper, employing the conformal transformation by which a unit circle and its exterior region can conformally mapped to a polygon and its exterior region, the author calculated two dimensional added inertia coefficients systematically for straight framed sections with single chine in horizontal and torsional modes of vibrations. As the results, it was found that sloping side angle is an important factor measuring the magnitude of two dimensional added inertia coefficient for a set of given values of the sectional area coefficient and the beam-draft ratio. To grasp it cleary in physical sense, pressure distributions are investigated for some typical section contours. The numerical results are presented graphically in the form of two dimensional added sectional area coefficients with beam-draft ratios and sloping side angles as parameters, so that the data may conveniently utilized for estimation of the added inertia coefficients based on a three parameter technique.

• Wind and Structures
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• v.36 no.1
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• pp.41-60
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• 2023

The effect of cladding panel size on the size reduction factor (SRF) of extreme area-averaging wind pressure (EAWP) on the facades of a high-rise building is often ignored in previous studies. Based on wind tunnel tests, this study investigated the horizontal and vertical correlations of wind pressure on the facade claddings of square-section high-rise buildings. Then, the influencing parameters on the SRF of the EAWP on the cladding panels were analyzed, which were the panel area, panel width, panel length and building width. The results show clear regional distinctions in the correlation of wind pressures on the building facades and the rules of the horizontal and vertical correlations are remarkably different, which causes the cladding size ratio to impact the SRF significantly. Therefore, this study suggests the use of the non-dimensional comprehensive size parameter b^𝜶h^1-𝜶/B (𝜶 is the fitting parameter) determined by the cladding panel horizontal size b, cladding panel vertical size h and the building width B rather than the cladding panel area to describe the variation of the EAWP. Finally, some empirical formula for the SRF of the EAWP on the cladding of a high-rise building is proposed with the nondimensional comprehensive size parameter.

• Journal of the Korean Society of Clothing and Textiles
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• v.18 no.5
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• pp.628-636
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• 1994

One vertical (medianus) and six horizontal (chest, bust, below bust, waist, abdomen and hip) sections of nine healthy pregnant women were examined every month by siliding gauge method during the period from 3rd to loth monthes of pregnancy. In the body changes along the passing months of pregnancy, which were observed by a follow·up measurement, there was little change on the posterior line when viewed using a vertical cross section. On the contrary, there was a great deal of increase on the anterior median line. Particularly, the degree of protrusion was great in the waist and ubilicus area due to pregnancy. At early pregnancy the distance from front to back is much shorter than side to side, however, as pregnancy progressed the front to back distance, on a horizontal cross section, is almost equal to the side to side distance.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.2064-2070
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• 1995

Characteristics of thermal flow stratification were studied experimentally by using the small scale pressurizer-surge line model. Thermal flow stratifications in the horizontal section of surge line were analyzed by the relation between the maximum temperature difference at any cross section in surge line and the Froude number representing the boundary conditions, i.e., in/out surge flow velocity and temperature difference of system. Thermal flow stratifications in outsurge flow decreased inversely proportional to the Froude number and did not exist for Fr>1. In insurge flow thermal flow stratifications disappeared near Fr=1.5, but resulted in the higher temperature difference than the case of outsurge flow.

• Structural Engineering and Mechanics
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• v.9 no.3
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• pp.227-240
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• 2000

The study of the optimal damping ratio of a tuned liquid-column damper (or TLCD) attached to a single-degree-of-freedom system is presented. The tuned liquid-column damper is composed of two vertical columns connected by a horizontal section in the bottom and partially filled with water. The ratio of the length of the horizontal section to the effective wetted length of a TLCD considered as another important parameter is also presented for investigation. A simple pendulum-like model test is conducted to simulate a long-period motion in order to prove the effectiveness of TLCD for vibrational control. Comparisons of the experimental and analytic results of the TLCD, TLD (tuned-liquid damper), and TMD (tuned-mass damper) are included for discussion.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.692-697
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• 2010

In this paper, a design program for electric railway pole foundation was developed by applying the estimation study performed by Korean Railway. There are two kinds of shapes in the cross-section of electric railway pole foundation: rectangle and circle. In foundation designing, The rectangular foundation should be satisfied with vertical, horizontal and moment equilibrium equations. On the other hand, the circular foundation should be satisfied with horizontal and moment equilibrium equations. The design program was coded into MFC(Microsoft Foundation Class) by MS Visual C. The equation's roots in the program were obtained by Incremental Search method. Dialog and property sheet(Wizard Mode) input windows were selected for user-friendliness. The biggest advantage of this program is to find an optimum depth in a given section.

• Journal of the Korean Society of Clothing and Textiles
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• v.19 no.2
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• pp.366-379
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• 1995

This study was performed to provide fundamental data on middle-aged women's upper torso by classifying the upper torso somatotype and analyzing the characteristics of their somatotype. Factor analysis of principal component model was used to 38 directly measured items, and cluster analysis was applied for classification of upper torso forms. Seven factors were extracted from the factor analysis. The first factor represented the items of circumference, breadth, and depth which were related with body size. On the basis of the cluster analysis using factor scores trom factor analysis as being independent variables, the subjects were classified into three groups. Three dress forms were constructed according to the characteristics for each somatotype of subjects, the three-dimensional characteristics of somatotype were analyzied by the moire pattern and horizontal section map of proposed dress forms. Wearing test by moire topography was used to evaluate wearing outline, the ease of clothes and garment space. Moire pattern and horizontal section map were useful to evaluate wearing conditions, and garment space was changed by the characteristics of the body shape.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.930-937
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• 2008

From the result of precise field investigation and stability analysis for the cut slope, following results were acquired. 1. The cause of the collapse of cut slope came from circle sliding collapse by fault zone which remained inner weathering zone. 2. The existing destructed soil and rock can be removed by reinforcement. And to prevent the additional destruction, it is judged that applying the method after relaxing the slope would be reasonable. 3. To make cut slope stable, soft rock layer should be done cutting 1:1.5 and 1:2.0 ~ 1:2.5 for weathered rock and soil layer. 4. Heavy water leakage section should be applied horizontal drain method so that water pressure should not act to the cut slope.