• Journal of Chest Surgery
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• v.27 no.10
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• pp.838-845
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• 1994

From April, 1982 to December, 1992, multiple valve replacement was performed in 100 patients. Mitral and aortic valve replacement were done in 86 patients, 9 underwent mitral and tricuspid valve replacement, 4 patients underwent triple valve replacement and 1 patient underwent aortic and tricuspid valve replacement. Of the valve implanted, 100 were St. Jude, 64 Duromedics, 19 Carpentier-Edwards, 13 Bj rk-Shiley, 6 Ionescu-Shiley, and 2 Medronics.The hospital mortality rate was 15%[15 patients] and the late mortality rate was 7%[7 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, 11.1% at 1989, 12.5% at 1990, 11.8% at 1991, 0% at 1992]. The causes of death were low cardiac output in 8, sudden death in 3, CHF in 3, bleeding in 2, cerebral thromboembolism in 1, leukemia in 1, multiorgan failure in 1 and so on. The actuarial survival rate excluding operative death was 73% at 10 years.

• Journal of the military operations research society of Korea
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• v.25 no.2
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• pp.144-157
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• 1999

In this paper, we consider a new preventive replacement policy for the system which deteriorates while it is in operation with an increasing failure rate. The system is subject to two types of failure. A type 1 failure is repairable while a type 2 failure is not repairable. In the new policy, a system is replaced at the age of $t_p$ or at the instant the$\textsc{k}^{th}$ type 1 failure occurs, whichever comes first. However, if a type 2 failure occurs before a preventive replacement is performed, a failure replacement should be made. We assume that a type 1 failure can be rectified with a minimal repair. We also assume that a replacement takes a non-negligible amount of time while a minimal repair takes a negligible amount of time. Under a cost structure which includes a preventive replacement cost, a failure replacement cost and a minimal repair cost, we develop a model to find the optimal ($\textsc{k},t_p$) policy which minimizes the expected cost per unit time in the long run while satisfying a system availability constraint.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.57-61
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• 2006

Waste foundry sand of industrial waste which is happening by vast quantity according to fast development of industry has much the occurrence amount and processing method is depended on reclamation, and is using by fine aggregate for construction by recycling method among others. In this research Waste foundry sand powder into cement replace fare use possibility availability judge wish to Slump and air content decreased the replacement ratio increases by concrete special quality that do not harden according to experiment result, and unit capacity mass and bleeding increased the replacement ratio increases. Hardening concrete intensity special quality displayed strength improvement to replacement ratio 20%, and tendency that watertightness increases most in replacement ratio loft in watertight property appear. Considering the strength and watertight properties, the adequate usage of waste foundry sand powder is the 10% of replacement ratio.

• Journal of Applied Reliability
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• v.17 no.3
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• pp.188-196
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• 2017

Purpose: The purpose of this research is to determine optimal replacement age using non-informative prior information and Bayesian method. Methods: We propose a novel approach using Bayesian method to determine the optimal replacement age in block replacement policy by defining the prior probability with data on failure time and repair time. The Marcov Chain Monte Carlo simulation is used to investigate the asymptotic distribution of posterior parameters. Results: An optimal replacement age of block replacement policy is determined which minimizes cost and nonoperating time when no information on prior distribution of parameters is given. Conclusion: We find the posterior distribution of parameters when lack of information on prior distribution, so that the optimal replacement age which minimizes the total cost and maximizes the total values is determined.

• Journal of Information Processing Systems
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• v.14 no.3
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• pp.631-644
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• 2018

Many studies on flash memory-based buffer replacement algorithms that consider the characteristics of flash memory have recently been developed. Conventional flash memory-based buffer replacement algorithms have the disadvantage that the operation speed slows down, because only the reference is checked when selecting a replacement target page and either the reference count is not considered, or when the reference time is considered, the elapsed time is considered. Therefore, this paper seeks to solve the problem of conventional flash memory-based buffer replacement algorithm by dividing pages into groups and considering the reference frequency and reference time when selecting the replacement target page. In addition, because flash memory has a limited lifespan, candidates for replacement pages are selected based on the number of deletions.

• Journal of Chest Surgery
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• v.27 no.6
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• pp.444-450
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• 1994

From June 1984 to February 1994, cardiac valve replacement was performed in 108 patients. The distribution of patients was ranged from 13 to 64 year-old age[mean 39.48 1.24] and 51 patients were male, 57 patients were female [male:female=1:1.1]. 64 patients had mitral valve replacement, 27 patients underwent aortic valve replacement and 17 patients were performed double[mitral & aortic] valve replacement. Total 125 artificial cardiac valves were used, mechanical valves were 51 valves and tissue valves were 74 valves. The duration of follow-up was 473.41 patient-year[mean 4.79 3.29 patient-year] and the information of follow-up was available for 99 patients[92%]. The actuarial survival rates including the operative mortality was 89.5% & 88.3 at postoperative fourth & ninth year. The probability of freedom from overall valve failure, thromboembolism and bacterial endocarditis were 77.5%, 89.2% and 95.6% at ninth year after cardiac valve replacement.

• PNF and Movement
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• v.9 no.1
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• pp.39-45
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• 2011

Purpose : The purpose of this article was to review the literature on change of knee position sense after total knee replacement intervention in knee rehabilitation. Methods : This review outlines scientific findings regarding different literature data in knee rehabilitation, and discusses proprioceptive change of knee joints after total knee replacement intervention. Result : Severe pain and diminished joint sensation may precipitate degenerative changes of knees joint, and a strong association between decreased proprioception and function has been identified in elderly patients with knee osteoarthritis. Total knee replacement(TKR) of the knee joint are effective surgical procedures in osteoarthritis patients, resulting in decreased pain, and improved physical function and quality of life in patients. After total knee replacement, joint position sensation is partially recovered, which may improve functional stability of the knee, but aspects of physical functioning are not fully restored to preoperative status. Conclusions : Thus, recovery rate in proprioception after TKR also is considered to be important because it may be a significant risk factor in failure of total knee replacement and knee rehabilitation intervention.

• Journal of Chest Surgery
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• v.8 no.2
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• pp.89-100
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• 1975

Sixteen cases of cardiac valve replacements have been done in this department since 1970. Twelve cases of mitral valve replacement were done with Beall valve, 2 cases of aortic valve replacement with Starr-Edwards and Magoven valve and 2 cases of double valve replacement using Beall valve for mitral and Magovern valve for aortic. Three patients [18.8%] died during operation. Two cases [12.5%] of hospital mortality occurred because of congestive heart failure and asphyxia due to tracheomalacia 3 months after operation. Follow-up studies from two to 27 months showed excellent results except three cases of late mortality [18.8 %]. Thromboembolism occurred in two double valve replacement patients[12.5%]who were fatal.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.881-887
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• 2005

A total knee replacement is an extremely 'position-sensitive' operation; a malposition or a malalignment of the components will lead to a breakage of the component, a fracture around the knee prosthesis, and the limitation of range of the motion, etc. In a conventional total knee replacement, surgeons have to select an appropriate prosthesis according to the shape of the surgical region. A wrong selection may give rise to side effects or to need re-operation. Nevertheless, it is so difficult to choose the most proper prosthesis out of various kinds of prosthesis. This paper presents a surgical planning system for the total knee replacement with an operation simulating method in order to determine the parameters for the total knee replacement operation. We select an alignment axis and a resection angle as major operation parameters in the total knee replacement operation, and introduce the method to determine the major operation parameters with the operation simulator we developed. The simulator is used to determine operation parameters for optimized operations, to select the most appropriate prosthesis, and to analyze the prospective problems of the operation.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.5
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• pp.509-516
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• 2014

This study describes a reasonable planning method for water meter replacement which can minimize the metering under-registration for an increasement of revenue water. The increment analysis of real water usage was used to establish a replacement plan. The meter replacement database collected from K City was used as the basis of this analysis. The database included 964 connections of domestic and non-domestic consumers that had their meter replaced by aging at 2011. The result showed that the corelation between unregistered water volume and water meter age was lower than commonly expected where the current criteria of replacement is only water meter age(8 years) excluding the meters older than 13 years. And in the analysis result of water usage for 8 years, the total amount and increment of water usage had a significant effect on unregistered water volume. However the relation was different tendency as a total volume and slope of increment. In case of total water volume was larger than 10,000, larger than 7,000 and increment of 0.0 ~ -0.3, larger than 6,000 and increment more than -0.3 were analysed to need a replacement because of metering under-registration.