• Journal of Chest Surgery
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• v.23 no.2
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• pp.213-221
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• 1990

We have experienced 62 cases of modified Fontan operations in Seoul Nat’l University Hospital from Apr. 1986 to Jul. 1989, They were 38 males and 24 females, and their age was ranged from 16 months to 15.5 years of age. [mean age : 5.73$\pm$2.99 years] There were 16 operative deaths and 2 late deaths, therefore 29% of overall mortality. Their diagnoses were as follows; 28 single ventricle, 11 tricuspid atresia, 6 DORV with LV hypoplasia, 3 pulmonary atresia with hypoplastic RV, 3 TGA with hypoplastic RV, 3 cor\ulcornerGA with hypoplastic LV and PA, 6 AV canal defects with PA, and 2 others. Low cardiac output and pleural effusion were developed frequently, so we divide 40 patients into some groups to analyze the physiologic and anatomic causes of them. By the degree of the LCO, group A was no LCO[mean amount of inotropics used: 0-5 \ulcornerg/kg/min] with 17 cases, B mild LCO [5-10] with 11, C moderate to severe LCO but alive[>10] with 8, D severe LCO to death with 4 cases. For the pleural effusion, group 1 was to be removed the chest tube within 1 week with 8 cases, group II within 3 weeks with 21 cases, group III beyond 3 weeks with 12 cases. We considered their age, diagnosis, pulmonary artery size[PA index], pulmonary artery abnormality, palliative shunt, systemic ventricular type, pulmonary artery wedge pressure, as preoperative factors, and operative methods, and as postoperative factors, CVP, LAP, arrhythmia, thrombosis, atrioventricular valvular insufficiency, etc. In the view of LCO, pulmonary artery size and PCWP were statistically significant [P<0.05], and arrhythmia, A-V valve insufficiency were inclined to the group C and D Pleural effusion was influenced by the pulmonary artery size, pulmonary artery resistance, PCWP, and CVP significantly. [P<0.05] And arrhythmia, residual shunt, and A-V valvular insufficiency were inclined to group II and III, too. As a results, the followings are to be reminded as the important factors at the care of post-Fontan LCO, and persistent pleural effusion [1] pulmonary artery size, [2] pulmonary artery resistance, [3] PCWP, [4] CVP, [5] arrhythmia, [6] residual shunt, [7]A-V valvular insufficiency.

• Journal of Pharmaceutical Investigation
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• v.33 no.4
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• pp.311-317
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• 2003

Felodipine is a calcium antagonist that lowers blood pressure by reducing peripheral resistance by meas of a direct, selective action on smooth muscle in arterial resistance vessels. Futhermore, it have been approved for the effective in angina pectoris and cardiac failure. The purpose of the present study was to evaluate the bioequivalence of two felodipine extended release (ER) tablets, Splendil (YuHan Corporation) and Stapin (Hana Pharmaceutial Co., Ltd.), according to the guidelines of Korea Food and Drug Administration (KFDA). The felodipine release from the two felodipine formulations in vitro was tested using KP VIII Apparatus II method at pH 6.5 buffer solution. Twenty six healthy male subjects, $22.73{\pm}1.78$ years in age and $66.66{\pm}7.28\;kg$ in body weight, were divided into two groups and a radomized $2{\times}2$ cross-over study was employed. After two tablets containing 5 mg as felodipine were orally administered, blood sample was taken at predetermined time intervals and the concentrations of felodipine in serum were determined using column-switching HPLC method with UV detector. The dissolution profiles of two formulations were similar at pH 6.5 buffer solution. Besides, the pharmacokinetic parameters such as $AUC_t,\;C_{max}\;and\;T_{max}$ were calculated and ANOVA test was utilized for the statistical analysis of the parameters using logarithmically transformed $AUC_t\;and\;C_{max}$ and untransformed $T_{max}$. The results showed that the differences between two formulations based on the Splendil were 2.53%, 1.32% and 18.32% for $AUC_t,\;C_{max}\;and\;T_{max}$, respectively. There were no sequence effects between two formulations in these parameters. The 90% confidence intervals using logarithmically transformed data were within the acceptance rage of log(0.86) to log(1.25) $(e.g.,\;log(0.86){\sim}log(1.20)\;and\;log(0.89){\sim}log(1.23)\;for\;AUC_t,\;C_{max},\;respectively)$. Thus, the criteria of the KFDA guidelines for the bioequivalence was satisfied, indicating Stapin ER tablet and Splendil ER tablet are bioequivalent.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2001.11a
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• pp.7-7
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• 2001

The increasing interest in light weight materials coupled to the need for cost -effective processing have combined to create a significant opportunity for aluminum P/M. particularly in the automotive industry in order to reduce fuel emissions and improve fuel economy at affordable prices. Additional potential markets for Al PIM parts include hand tools. Where moving parts against gravity represents a challenge; and office machinery, where reciprocating forces are important. Aluminum PIM adds light weight, high compressibility. low sintering temperatures. easy machinability and good corrosion resistance to all advantages of conventional iron bm;ed P/rv1. Current commercial alloys are pre-mixed of either the AI-Si-Mg or AL-Cu-Mg-Si type and contain 1.5% ethylene bis-stearamide as an internal lubricant. The powder is compacted in closed dies at pressure of 200-500Mpa and sintered in nitrogen at temperatures between $580~630^{\circ}C$ in continuous muffle furnace. For some applications no further processing is required. although most applications require one or more secondary operations such as sizing and finishing. These sccondary operations improve the dimension. properties or appearance of the finished part. Aluminum is often considered difficult to sinter because of the presence of a stable surface oxide film. Removal of the oxide in iron and copper based is usually achieved through the use of reducing atmospheres. such as hydrogen or dissociated ammonia. In aluminum. this occurs in the solid st,lte through the partial reduction of the aluminum by magncsium to form spinel. This exposcs the underlying metal and facilitates sintering. It has recently been shown that < 0.2% Mg is all that is required. It is noteworthy that most aluminum pre-mixes contain at least 0.5% Mg. The sintering of aluminum alloys can be further enhanced by selective microalloying. Just 100ppm pf tin chnnges the liquid phase sintering kinetics of the 2xxx alloys to produce a tensile strength of 375Mpa. an increilse of nearly 20% over the unmodified alloy. The ductility is unnffected. A similar but different effect occurs by the addition of 100 ppm of Pb to 7xxx alloys. The lend changes the wetting characteristics of the sintering liquid which serves to increase the tensile strength to 440 Mpa. a 40% increase over unmodified aIloys. Current research is predominantly aimed at the development of metal matrix composites. which have a high specific modulus. good wear resistance and a tailorable coefficient of thermal expnnsion. By controlling particle clustering and by engineering the ceramic/matrix interface in order to enhance sintering. very attractive properties can be achicved in the ns-sintered state. I\t an ils-sintered density ilpproaching 99%. these new experimental alloys hnve a modulus of 130 Gpa and an ultimate tensile strength of 212 Mpa in the T4 temper. In contest. unreinforcecl aluminum has a modulus of just 70 Gpa.

• Wind and Structures
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• v.23 no.6
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• pp.559-575
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• 2016

In order to investigate the influence of different blade positions on aerodynamic load and wind loads and load-effects of large scale wind turbine tower under the halt state, we take a certain 3 MW large scale horizontal axis three-blade wind turbine as the example for analysis. First of all, numerical simulation was conducted for wind turbine flow field and aerodynamic characteristics under different halt states (8 calculating conditions in total) based on LES (large eddy simulation) method. The influence of different halt states on the average and fluctuating wind pressure coefficients of turbine tower surface, total lift force and resistance coefficient, circular flow and wake flow characteristics was compared and analysed. Then on this basis, the time-domain analysis of wind loads and load-effects was performed for the wind turbine tower structure under different halt states by making use of the finite element method. The main conclusions of this paper are as follows: The halt positions of wind blade could have a big impact on tower circular flow and aerodynamic distribution, in which Condition 5 is the most unfavourable while Condition 1 is the most beneficial condition. The wind loads and load-effects of disturbed region of tower is obviously affected by different halt positions of wind blades, especially the large fluctuating displacement mean square deviation at both windward and leeward sides, among which the maximum response occurs in $350^{\circ}$ to the tower top under Condition 8; the maximum bending moment of tower bottom occurs in $330^{\circ}$ under Condition 2. The extreme displacement of blade top all exceeds 2.5 m under Condition 5, and the maximum value of windward displacement response for the tip of Blade 3 under Condition 8 could reach 3.35 m. All these results indicate that the influence of halt positions of different blades should be taken into consideration carefully when making wind-resistance design for large scale wind turbine tower.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.4
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• pp.261-267
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• 2010

The pyrometallurgical nuclear fuel recycle process, called pyroprocessing, has been known as a promising nuclear fuel recycling technology. Pyroprocessing technology is crucial to advanced nuclear systems due to increased nuclear proliferation resistance and economic efficiency. The basic concept of pyroprocessing is group actinide recovery, which enhances the nuclear proliferation resistance significantly. One of the key steps in pyroprocessing is "electrowinning" which recovers group actinides with lanthanide from the spent nuclear fuels. In this study, a vertical cadmium distiller was manufactured. The evaporation rate of pure cadmium in vertical cadmium distiller varied from 12.3 to $40.8g/cm^2/h$ within a temperature range of 773 923 K and pressure below 0.01 torr. Uranium - cadmium alloy was fabricated by electrolysis using liquid cadmium cathode in a high purity argon atmosphere glove box. The distillation behavior of pure cadmium and cadmium in uranium - cadmium alloy was investigated. The distillation behavior of cadmium from this study could be used to develop an actinide recovery process from a liquid cadmium cathode in a cadmium distiller.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.107-114
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• 2017

A turbocharger is an engine supercharger that is driven by exhaust gas. It improves the output and fuel efficiency by increasing the charging efficiency of the mixture gas, which is achieved by changing the rotatory power of the turbine connected to the exhaust passage. It is important to control the supercharging for this purpose. A nozzle slide joint is one of the core parts. Austenitic stainless steel is currently used as the material for this part, and its excellent mechanical properties include high heat resistance and corrosion resistance. However, because of its poor machinability, there are many difficulties in producing products with complicated shapes. Machining is used in the production of nozzle slide joints for high dimensional accuracy after metal powder injection molding. As design variables in this study, we investigated the sintering temperature, product stress, deformation rate, radius of curvature of the punch, and angle of the chamfer punch, which are related to the strain and shapes. The goal is to suggest a forming process using Nitronic 60 that does not require machining to manufacture a nozzle slide joint for a turbocharger. Accordingly, we determined the best process environment using finite-element analysis, the signal-noise ratio, and the Taguchi method for experiment design. The relative density and hydrostatic pressure of the final product were in accordance with the results of the finite element analysis. Therefore, we conclude that the Taguchi method can be applied to the design process of metal powder injection molding.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.4
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• pp.21-31
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• 2001

When an oil-spilling accident occurs at sea, it is of the primary importance to predict the amount of oil leakage for the swift response and decision-making. The simplest method of oil-leakage estimation is based on the hydrostatic pressure balance between oil inside the tank and seawater outside of leakage hole, that is the so-called Torricelli equilibrium relation. However, there exists discrepancy between the reality and the Torricelli relation, since the latter is obtained from the quasi-steady treatment of Bernoulli equation ignoring viscous friction. A preliminary experiment has been performed to find out the oil-leaking speed and shape. Soy-bean oil inside the inner tank was ejected into water of the outer tank through four different leakage holes to record the amount of oil leakage. Furthermore, a CFD (Computational Fluid Dynamics) method was utilized to simulate the experimental situation. The Wavier-Stokes equations were solved for two-density flow of oil and water. VOF method was employed to capture the shape of their interface. It is found that the oil-leaking speed varies due to the frictional resistance of the leakage hole passage dependent on its aspect ratio. The Torricelli factor relating the speed predicted by using the hydrostatic balance and the real leakage speed is assessed. For the present experimental setup, Torricelli factors were in the range of 35%~55% depending on the aspect ratio of leakage holes. On the other hand, CFD results predicted that Torricelli factor could be 52% regardless of the aspect ratio of the leakage holes, when the frictional resistance of leakage hole passage was neglected.

• Journal of the Korean Magnetics Society
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• v.17 no.2
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• pp.86-89
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• 2007

[ $FeCr_2Se_4$ ] prepared under the high pressure (3 GPa) has been studied with x-ray, neutron diffraction techniques, superconducting quantum interference device (SQUID) magnetometer, resistance, and Mossbauer spectroscopy. The temperature dependence of resistance is explained by Mott-VRH and small polaron model for the regions I (T<20 K) and II (T>42 K), respectively. Neutron diffraction results show an antiferromagnetic spin-lattice coupling near the Neel temperature. So finally the distance of atom is enlarged in region (110$FeCr_2Se_4$ shows convex type of temperature dependence.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.867-873
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• 2010

This study investigated the corrosion properties of reinforced concrete with the addition of steel fibers. The transport properties of steel fiber-reinforced concrete such as permeable void, absorption by capillary action, water permeability and chloride diffusion were first measured to evaluate the relationship with the corrosion of steel rebar. Test results showed a slight increase on the compressive strength with the addition of steel fibers as well as considerable improvement of penetration resistance to mass transport of harmful materials into concrete. The addition of steel fibers in reinforced concrete accelerated the initiation of steel corrosion contrary to the expected results based on the measured transport properties. The NaCl ponding surface showed the spalling failure due to the corrosion expansion of steel fibers and the cut-surface around the steel rebar showed the localized steel fiber's corrosion. The wet-dry cycling with high chloride ions as well as high temperature seems to induce the increase of salt crystallization on the pores continually and the increased pressure with the steel fiber's corrosion on the pores caused the spalling failure on the exposed surface. The microcracking on the surface therefore accelerated the movement of water, chloride ions and oxygen into the embedded steel rebar. The mechanism affecting corrosion of embedded steel reinforcement with steel fibers in this study are not yet fully understood and require further study comprising of accurate experimental design to isolate the effect of steel fiber's potential mechanism on the corrosion process.

• Journal of the Korean Geotechnical Society
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• v.19 no.1
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• pp.93-102
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• 2003

Unconfined compression test (UC) has been widely used to determine the undrained shear strength ($c_u$) of clay, because it is convenient and economical. However, UC can not represent the behaviour of in-situ stress condition and the strength obtained by the test is generally underestimated compared to that of triaxial compression, due to no confining pressure. Therefore, a simple and practical method to correct the ($c_u$) for sample disturbance and to be used in geotechnical practice is needed. This study is aimed at proposing the method to estimate in-situ undrained shear strength from UC with suction measurement. The proposed method is based on theoretical shear strength equation of perfect sample (Noorany & Seed, 1965), and effective overburden stress and analysis results ($A_f,\phi'$) of effective stress behaviour by UC are needed for the equation. The shear resistance angle ($\phi'$) can be simply estimated through the result that $K_f$-line slope of the UC is 1.6 times higher than that of triaxial compression test. The result of this study shows that the measured strength by this method is very similar to that of the undrained shear strength by triaxial compression test (CK$_0$UC).