• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.2
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• pp.199-204
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• 2013

Recently, the demand for fuel efficient electric vehicles (EVs) and hybrid electric vehicles (HEVs) has been growing globally. Due to the increased number of switching devices in the electrified vehicles, the probability of the semiconductor device failure is much higher than in other application areas. A sudden failure in one of the power switches and insufficient power management ability in the systems not only decreases system performance, but also leads to critical safety problems. In this paper, novel switch open circuit fault detection method is proposed, and the proposed approach is verified by experiments.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.321-326
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• 1998

Shear failure of reinforced concrete beams is serious problem due to sudden brittle failure and many experimental results proved that size effect in shear behavior is an important feature of reinforced concrete members. For this reason, the structural safety of the reinforced concrete beams for shear has been checked by applying empirical design formula, which includes the size-effect, derived from experimental data. However, as the sizes of reinforced concrete members become extremely large, experiments sometimes become very difficult so that the formula or the experimental data could not be obtained and size-effect analyses of shear behavior become significant. In this study, size-effect analysis of shear behavior in reinforced concrete beams is performed by modeling tension stiffening/shear stiffening on reinforced concrete and the tension softening/shear softening on plain concrete. Then, the influences of models in the size-effect analyses of shear behavior in reinforced concrete beams are analyzed.

• Journal of Chest Surgery
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• v.22 no.6
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• pp.970-979
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• 1989

From April 1982 to December, 1988, multiple valve replacement was performed in 49 patients. Mitral and aortic valve replacement were done in 42 patients, 4 underwent mitral and tricuspid valve replacement and 3 patients underwent triple valve replacement. Of the valve implanted, 50 were Duromedics, 21 St. Jude, 13 Bjork-Shiley, 9 Carpentier-Edwards, 6 Ionescu-Shiley, and 2 Medtronic. The hospital mortality rate was 28.5 % [14 patients] and the late mortality rate was 6.1 % [3 patients], the mortality rate was high in early operative period but decreased with time. [20% at 1986, 18.2 % at 1987, 9.5% at 1988] The causes of death were low cardiac output in 8, congestive heart failure in 2, multiple organ failure in 1, LV rupture in 1, intracerebral hemorrhage in 1 and sudden death in l. The actuarial survival rate excluding operative death was 77% at 7 years.

• Journal of Chest Surgery
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• v.28 no.12
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• pp.1113-1121
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• 1995

From August, 1986 to December, 1993, mitral valve replacement was performed in 178 patients. Of the valve implanted, 114 were St.Jude Medical, 47 Duromedics, 16 Carpenter-Edward and 1 Ionesc-Shiley. The hospital mortality rate was 2.8%[5 patients and the late mortality rate was 7.5%[13 patients . The causes of hospital death were LV rupture in 1, renal failure in 1, cardiac tamponade in 1, valve malfunction in 1 and hypoxic brain damage in 1. The causes of late death were sudden death in 6, congestive heart failure in 4, brain ischemic injury in 3. Follow-up was done on 155 surviving patients : mean follow-up period was 50.94$\pm$8.04 months. The actual survival rate was 88.2% at 8 years. We concluded, therefore, that good clinical results could be achieved with mitral valve replacement in mid-term follow-up, and long-term follow-up is also necessary.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.2
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• pp.93-102
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• 2001

The objective of this experimental study is to evaluate the strengthening effects of concrete compression confined with Epoxy-boned compound fiber sheets. An analytical model is proposed to construct a stress-strain relationship for confined concrete. Test results are summarized as followed. While non-FRP lateral confinement specimens appeared sudden failure after shell concrete was torn off, specimens confined laterally with FRP were showed that their failure. Specially, Glass fiber lateral confined specimens occurred obviously increase ductility ability. Hence, concrete specimen with lateral confinement by Hi-carborn and Aramide. Glass fiber simultaneously can be increased in not only strength but also a lot of ductility ability.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.7_spc
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• pp.545-551
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• 2016

This paper investigates seismic performance of a small-sized single story building in Korea. Nonlinear pushover anlaysis is performed to verify shear failure of RC short columns eventually led to performance degradation. Also, nonlinear time history analysis is performed using the same earthquakes from Gyeongju. Similar failure mode was obtained as in the report where a sudden rupture of the RC columns happened.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1697-1702
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• 2004

The waterhammer has recently become more important because the pumping stations were big and the systems conveying the fluid through the large and long transmission pipelines were complex. When the pumps are started or stopped for the operation or tripped due to the power failure. the hydraulic transients occur as a result of the sudden change in velocity. In this paper, the field tests on the waterhammer by the startup, stoppage, and power failure of a centrifugal pump were carried out for Yongma transmission pumping station in Seoul. The experimental results were compared with that of the numerical calculations. in which results the procedure of controlled pump normal shut-down and the two-step closing mode of controlling the ball valve for pump emergency stop are proposed to reduce the pressure surge.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.1
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• pp.8-13
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• 2010

The shaft surface machining is a popular machine for studying descale machine design and process in automobile industry. In this study, the descale design machine of cutting shaft surface was conducted for the detection of a tool failure in surface process. Induction harden surface is used as analyzing function to detect a sudden change in cutting process level. A preliminary stepped workpiece which had a hard condition was cut by the surface tool and a tool process obtained cutting force machine. At machine failure, the results were suddenly increased and the detailed surfaces were extremely obtained.

• Journal of Chest Surgery
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• v.33 no.2
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• pp.160-166
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• 2000

Background: The purpose of this study is to evaluate and analyze the surgical results in patients undergoing operations for multiple for multiple valvular heart diseases. Material and method: From April 1982 to June 1997 multiple valve replacement was performed in 150 patients mitral and aortic valve replacement were done in 135 patients mitral and tricuspid valve replacements in 10 patients triple replacements in 4 patients and aortic and tricuspid valve replacement in 1 patient. Of the valves implanted 157 were St. Jude 104 Duromedics 20 Carpenter-Edwards 6 Bjork-Shiley 6 Ionescu-Shiley and 2 Medtronics. Result: The hospital mortality rate was 10.7% (16/150) and the late mortality rate was 7.2% (8/134) The mortality rate was high in early operative period but decreased with time. The causes of death were low cardiac output in 9 sudden death in 3 congestive heart failure in 3 bleeding in 2 cerebral thrombosis in 1 leukemia in 1 multiorgan failure in 1 and so on . The actuarial survival rate excluding operative death was 83.1% at 15 years. Conclusion: With a follow-up now extending to 15 years the multiple valve replacement continues to be reliable procedure with relatively low mortality and morbidity.

• Journal of Chest Surgery
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• v.48 no.1
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• pp.52-54
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• 2015

Idiopathic pulmonary arterial hypertension eventually leads to right-sided heart failure and sudden death. Its mortality rate in children is still high, despite improvements in pharmacological therapy, and therefore novel treatments are necessary. The Potts shunt, which creates an anastomosis between the left pulmonary artery and the descending aorta, has been proposed as a theoretically promising palliative surgical technique to decompress the right ventricle. We report the case of a 12-year-old girl with suprasystemic idiopathic pulmonary hypertension and right ventricular failure who underwent a Potts shunt for palliation with good short-term results.