• Journal of Chest Surgery
• /
• v.22 no.4
• /
• pp.594-600
• /
• 1989

Primary intracardiac repair of tetralogy of Fallot with low mortality and early good results, has been accomplished in recent years. But palliative procedures have been reserved for those hypoplastic pulmonary arteries, a hypoplastic left ventricle or anomalies of the coronary artery would make total correction difficult. And the Blalock-Taussig shunt operation is recognized as a standard and popular palliative procedure. I undertook a retrospective determination of the effect of the Blalock-Taussig shunt operation on the development of the main pulmonary artery and the right and left pulmonary arteries. Between January, 1980, and April, 1987, at the Severance Hospital, 16 patients were studied by cardiac catheterization and angiocardiography, before undergoing Blalock-Taussig shunting procedures for the palliation of severe symptoms of tetralogy of Fallot, and some time later, usually prior to a second procedure. The mean interval between catheterizations was 22.25 months. Patients with tetralogy of Fallot and pulmonary atresia or with an occluded shunt were not included. The primary and secondary angiograms of each patient were reviewed, and measurements of the diameter of the main pulmonary artery, the right and left pulmonary arteries, and the descending thoracic aorta were taken. The results are as follows; 1. The hematocrit decreased from 56.39% to 50.34%[p< 0.05], and the arterial oxygen saturation increased from 62.00 % to 81.31 %[p< 0.001] following shunt procedures 2. The ratio of the diameter of the right pulmonary artery plus the left pulmonary artery to the diameter of the descending thoracic aorta increased 1.30 k 0.28 times [p< 0.01]; but the ratio of the diameter of the main pulmonary artery to the diameter of the descending thoracic aorta increased 1.10 * 0.33 times, which was not. significant[p< 0.05]. 3. The interval between shunting and second catheterization was not related to the magnitude of change in the pulmonary arteries[r=0.141, p >0.05]. 4. The changes in the ratio of the diameter of the right pulmonary artery plus the diameter of the left pulmonary artery to the diameter of the descending thoracic aorta was inversely related to the initial ratio[r=0.757, p >0.001], but the change in the ratio of the diameter of the main pulmonary artery to the descending thoracic aorta was not related[r=0.059, p >0.05]. 5. There were no differences in enlargement of the pulmonary artery on the side of the shunt [ipsilateral] versus enlargement on the opposite side [p >0.05], nor according to the size of the shunt[p >0.05]. In conclusion, this study suggests that the Blalock-Taussig shunt is effective for the development of the right and left pulmonary arteries but not effective for the main pulmonary artery.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.34 no.2
• /
• pp.200-211
• /
• 1998

Heat transfer performance improvement by fin and groovs is studied for condensation of R-11 on integral-fin tubes. Eight tubes with trapczodially shaped integral-fins having fin density from 748 to 1654fpm(fin per meter) and 10, 30 grooves are tested. A plain tube having the same diameter as the finned tubes is also used for comparison. R-11 condensates at saturation state of 32 $^{\circ}C$ on the outside tube surface coded by inside water flow. All of test data are taken at steady state. The heat transfer loop is used for testing singe long tubes and cooling is pumped from a storage tank through filters and folwmeters to the horizontal test section where it is heated by steam condensing on the outside of the tubes. The pressure drop across the test section is measured by menas pressure gauge and manometer. The results obtained in this study is as follows : 1. Based on inside diameter and nominal inside area, overall heat transfer coefficients of finned tube are enhanced up to 1.6 ~ 3.7 times that of a plain tube at a constant Reynolds number. 2. Friction factors are up to 1.6 ~ 2.1 times those of plain tubes. 3. The constant pumping power ratio for the low integral-fin tubes increase directly with the effective area to the nominal area ratio, and with the effective area diameter ratio. 4. A tube having a fin density of 1299fpm and 30 grooves has the best heat transfer performance.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.1A
• /
• pp.9-18
• /
• 2009

This paper introduces the application of DE (Differential Evolutionary) method for the estimation of tensile force of the externally prestressed tendon. The proposed technique, a SI (System Identification) method using the DE algorithm, can make global solution search possible as opposed to classical gradient-based optimization techniques. The numerical tests show that the proposed technique employing DE algorithm is a useful method which can detect the effective nominal diameters as well as estimate the exact tensile forces of the externally prestressed tendon with an estimation error less than 1% although there is no a priori information about the identification variables. In addition, the validity of the proposed technique is experimentally proved using a scale-down model test considering the serviceability state condition without and with the loss of the prestressed force. The test results prove that the technique is a feasible and effective method that can not only estimate the exact tensile forces and detect the effective nominal diameters but also inspect the damping properties of test model irrespective of the loss of the prestressed force. The 2% error of the estimated effective nominal diameter is due to the difference between the real tendon diameter with a wired section and the FE model diameter with a full-section. Finally, The accuracy and superiority of the proposed technique using the DE algorithm are verified through the comparative study with the existing theories.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.822-825
• /
• 2004

Continuously variable transmission (CVT) mechanisms considered here is a V-belt drive with two variable-diameter pulleys and effective diameters. One pulley was set by a mechanical link while the other was spring-loaded to provide automatic correspondence. The center distance between the two variable-diameter pulleys was fixed. Experimental studies were executed to analyze efficiencies as change of its speed ratio.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.17 no.3
• /
• pp.3833-3839
• /
• 1975

The object of this experiment is to find out some flow characteristics of water through sand layer, to prevent moving sands in the filters of the fill Dam, infiltration gallery, well and Deversion Weir. This experiment was accomplished with different particle Sizes of Six Samples and different hydraulic gradient. The results obtained are Summarized as follows. 1. The critical hydraulic gradients for laminar flow was found to be between 1 and 2 when the sand used had the effective diameter, D10 of between 0.18cm and 0.45cm. 2. The critical hydraulic gradients for different particle sizes of sands were varied considerably. 3. There was a negative correlation between critical hydraulic gradient and critical Velocity, and between effective particle diameter D10 and critical hydraulic gradient respectively. 4. In spite of relatively small variation of void ratio of sands used, the values of the coefficient of permeability varied considerably. There was a negative correlation between coefficient of permeability and void ratio.

• Transactions of Materials Processing
• /
• v.19 no.6
• /
• pp.372-377
• /
• 2010

Elasto-plastic finite element analysis was performed for a burnishing process for the inner surface of a cylinder by mandrel. Three different configurations in roughness of the inner surface, two different thicknesses of the cylinder wall, and five different diameters of the mandrel were selected for the present investigation. Although the surface roughness was improved with the increase of the mandrel diameter, defects of folding occurred as the mandrel diameter exceeded certain limits. Improvements in the surface roughness, distributions of effective strain, effective stress and residual circumferential stress, and the variation of mandrel force were also investigated.

• Tribology and Lubricants
• /
• v.24 no.5
• /
• pp.234-240
• /
• 2008

It is well known that surface texturing improves the tribological properties of mechanical components for enhancing hydro-dynamic effect or serving as a micro reservoir. There are not, however, enough researches to reveal the effects of surface texturing on the tribological properties under grease lubrication which is used in lubricating many mechanical elements. In the present study, therefore, the effects of surface texturing on the tribological properties are investigated under grease lubrication based on an experimental approach. The results show that surface texturing decreases friction coefficient. It is found that the friction coefficient can be decreased by controlling the diameter and density of micro-dimple. The diameter of dimple is more effective under high load and low speed than otherwise. And, the density of dimple is effective under low load and high speed.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.15 no.3
• /
• pp.3096-3106
• /
• 1973

As a link in the chain of antidrought measure, our attempt is made to obtain basic informations on the construction of an infiltration gallary which can be supplied with irrigation water by catching of underground water in small river beds, which is economical, permanent and efficient. The experiment was made, concerning the structure of catchment conduits, by constructing a model sand tank $1.5m{\times}5m{\times}1.5m$ in dimension made of reinforced concrete. Various kinds of measuring equipment were attached to the model tank which contains a set of catchment conduits, each of them was made 30cm in diameter and 60cm in length with the ratio of sectional area to total area of influx holes 10:1, 20:1, 30:1. The average size of influx holes was fixed from 0mm to 10mm, 20mm and 30mm in diameter respectively. Obtained results are as follow; (a) In view of the water catchment capacity, manufacturing cost and the antipressure strength of the catchment conduits, it is the best method to decide the total number of influx holes 20 per sq. meter of each tile surface, and the size of influx holes 20mm in diameter, when the conduits have diameter less than 1m. (b) The greatest factor of safety against external load is to arrange the influx holes in a zigzag manner on the tile surface. The most effective formula of arrangement is $S{\geqq}\sqrt{2gd}$ where: s : spacing of opening row. g : spacing of opening line. d : diameter of influs hole.

• Journal of ILASS-Korea
• /
• v.11 no.4
• /
• pp.220-227
• /
• 2006

Experimental studies has been conducted to investigate the effect of orifice diameter ratio on the mixing characteristics of the split element of doublet and triplet elements. The spray characteristics of non-reacting immiscible liquids have been investigated using a patternator. The local volume fraction is measured by use of mean value of each component. This volume measurement represents the mixing characteristics of the liquid, which affect the overall combustion efficiency. The ratio of the orifice diameter, ranging from 1 to 1.5, and that of the jet-momentum, ranging from 0.5 to 6.0, we used. The jet impinging behavior with use of various ratios exhibits substantially different mixing characteristics. Mixing efficiency is maximized when the jet-momentum ratio is increased; this behavior is particularly prominent when the orifice diameter ratio is greater than unity. The split of the triplet element yields better mixing characteristics and is more effective than that of the doublet element in regard to achieving high combustion efficiency. The optimum mixing factor for the triplet element is found to be 0.75, according to our measurement.

• Journal of the Korean Society of Visualization
• /
• v.17 no.1
• /
• pp.60-68
• /
• 2019

Flow visualizations have been carried out to analyze the characteristics of bubby flows exhausted from a venturi-type bubble generator with an air vent. For various design parameters and operating conditions of the bubble generator, the images of bubbly flows was recorded using a high-speed camera and a microscope. Then the amount and size distribution of bubble was evaluated by an image processing technique. The results show that for increasing the amount of bubble, it is more effective to reduce the venturi throat than to enlarge the air vent diameter. If the water flow rate increases, the bubble generation rate increases but reaches a status of saturation, whose condition depends on Reynolds number at a given air vent diameter. The bubble size increases as the diameter of venturi throat decreases and Reynolds number increases. However, the air vent diameter is not a significant factor on bubble size.