• Journal of computational fluids engineering
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• v.8 no.2
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• pp.49-56
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• 2003

Three-dimensional endwall flow within a linear cascade passage of high performance turbine blade is simulated with a 3-D Navier-Stokes CFD code (MOSA3D), which is based on body-fitted coordinate system, pressure-correction and finite volume method. The endwall flow characteristics, including the development and generation of horseshoe vortex, passage vortex, etc. are clearly simulated, consistent with the generally known tendency. The effects of both turbulence model and convective differencing scheme on the prediction performance of endwall flow are systematically analyzed in the present paper. The convective scheme is found to have stronger effect than the turbulence model on the prediction performance of endwall flow. The present simulation result also indicates that the suction leg of the horseshoe vortex continues on the suction side until it reaches the trailing edge.

• Journal of computational fluids engineering
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• v.8 no.3
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• pp.1-6
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• 2003

Three-dimensional endwall flow within a linear cascade passage of high performance turbine blade is simulated with a 3-D Wavier-Stokes CFD code (MOSA3D), which is based on body-fitted coordinate system, pressure-correction and finite volume method. the endwall flow characteristics, including the development and generation of horseshoe vortex, passage vortex, etc. are clearly simulated, consistent with the generally known tendency The effects of both turbulence model and convective differencing scheme on the Prediction performance of endwall flow are systematically analyzed in the present paper. The convective scheme is found to have stronger effect than the turbulence modei on the prediction performance of endwall flow. The present simulation result also indicates that the suction leg of the horseshoe vortex continues on the suction side until it reaches the trailing edge.

• Journal of Power Electronics
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• v.8 no.3
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• pp.259-267
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• 2008

Power quality improvement in a three-phase four-wire system is achieved using a new topology of DSTATCOM (distribution static compensator) consisting of a star/delta transformer with a tertiary winding and a three-leg VSC (voltage source converter). This new topology of DSTATCOM is proposed for power factor correction or voltage regulation along with harmonic elimination, load balancing and neutral current compensation. A tertiary winding is introduced in each phase for a delta connected secondary in addition to the star-star windings and this delta connected winding is responsible for neutral current compensation. The dynamic performance of the proposed DSTATCOM system is demonstrated using MATLAB with its Simulink and Power System Blockset (PSB) toolboxes under varying loads. The capacitor supported DC bus of the DSTATCOM is regulated to the reference voltage under varying loads.

• Journal of Chest Surgery
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• v.17 no.4
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• pp.636-643
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• 1984

For the purpose of avoiding postoperative massive pulmonary insufficiency after transannular outflow tract reconstruction in patients with tetralogy of Fallot, we have used monocusp bearing outflow patch since June 1983. Right heart catheterization and pulmonary arteriography were performed in 7 patients among the total 11 patients corrected with monocusp bearing outflow patch during postoperative 14th day to 22nd day. Particular attention was paid to the evaluation of the pulmonary valve competence, and the results were; 1.One patient died of acute renal failure secondary to low cardiac output and the operative mortality was 9.1%. 2.The average PRV/FA ratio was 0.491 and the average systolic pressure gradient between right ventricle and pulmonary artery was 17.7mmHg. The average Qp/Qs was 1.13. 3.Inspite of using monocusp bearing outflow patch, the hemodynamic and pulmonary arteriographic results were unsatisfactory in respect to pulmonary valve competence.

• Journal of Chest Surgery
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• v.47 no.6
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• pp.541-544
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• 2014

Pseudoaneurysm of the right ventricular outflow tract (RVOT) has been reported as a rare complication of RVOT reconstruction performed using conduit replacement or patch repair. Rarely, it may present alongside symptoms secondary to the compression of adjoining mediastinal structures. We report the case of a patient who developed a symptomatic RVOT pseudoaneurysm one month after a total correction of tetralogy of Fallot. In the present case, superior vena cava syndrome was caused by compression of the superior vena cava, which was a very unusual presentation.

• Journal of Power Electronics
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• v.18 no.2
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• pp.383-394
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• 2018

This paper presents an isolated power factor correction converter for general-purpose electric vehicle chargers with a wide output voltage range. The converter is based on an asymmetrical dual active bridge structure so that the voltage stress of switching devices can be eliminated by transferring the transformer leakage inductance to the circuit parameters. Harmonic and output controls are performed by secondary switches, and primary switches are only operated at a fixed frequency with a 50% duty ratio. A harmonic modulation technique is also adopted to obtain a near-unity power factor without input current monitoring. The feasibility of the proposed charger is verified with a 3.3 kW prototype.

• Journal of Chest Surgery
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• v.10 no.1
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• pp.1-6
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• 1977

Two patients with funnel chest deformity corrected in the Department of Thoracic Surgery, Korea University Hospital are presented. The first case was a 21 year old male suffering from exertional dyspnea and recurrent upper respiratory tract infection with asymmetrical funnel Chest deformity, which the hollow cavity was measured 250ml of water. He was corrected by Ravitch method. The result was uneventful. The second case was a 34 year old male with symmetrical and asymptomatic deformity which the hollow cavity was measured 45ml of water. He was corrected by the method of sternal turnover [Wada Method]. On postoperative 8th day, seroma was noted in subxiphoid space and followed secondary infection of the pseudomonas. So, the infected cartilages were resected and curetted. The result was uneventful.

• Journal of Chest Surgery
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• v.23 no.6
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• pp.1139-1145
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• 1990

Seven infants less than age 3 months underwent patch aortoplasty and tube graft bypass for relief of coarctation of aorta. All had intractable congestive heart failure, despite aggressive medical therapy Each infant had other cardiac anomalies including patent ductus arteriosus, ventricular septal defect, atrial septal defect and congenital mitral stenosis. All patients underwent closure of the ductus arteriosus and patch angioplasty of the aorta to produce a luminal diameter of at least 15mm or tube graft interposition utilizing the Gortex tube graft diameter larger than 10mm. In 5 patients who had ventricular defect, they underwent pulmonary arterial banding. &ere was one hospital death 17 days after operation secondary to the hydronephrosis and renal failure. Hospitalization was less than 10 days after operation except one case. In 3 patients who had associated VSD, open heart surgery[VSD closure+PA debanding]was done without difficulty. Surgical repair of critical coarctation of the aorta in infants can safely be offered despite the poor preoperative condition and presence of other cardiac anomalies.

• Proceedings of The Korean Cleft Lip And Palate Association
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• 2003.06a
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• pp.26-26
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• 2003

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.2
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• pp.290-301
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• 1992

An experimental study has been performed to investigate the characteristics of forced convective heat transfer in a rectangular duct with a 180.deg. bend. The Nusselt number of outer wall has maximum value near 105.deg. at which secondary flow is most active and the Nusselt number of inner wall has maximum value near the inlet of a duct. Near the outlet of a duct, the Nusselt number of outer wall decreases, the Nusselt number of inner wall increases and so those access each other through the influence of a straight duct attached to the end of a duct with a 180.deg. bend. Results of this experimental study would be the fundamental data when streamline curvature correction models are developed in the numerical study for forced convective heat transfer in a curved duct.