• Journal of Chest Surgery
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• 제23권4호
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• pp.667-675
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• 1990

From June, 15th, 1987 to June, 14th, 1989, 105 Duromedics bileaflet cardiac valve prostheses were implanted in 81 patients. Mitral valve replacement was done in 42 patients, 7 underwent aortic valve replacement, 28 underwent double valve replacement, & 4 patients underwent triple valve replacement. Concomitantly used valves were 13 cases; 11 cases were St. Jude Medical valves[M: SJM #29 X4, #27 X5, #25 X 1, T: SJM #33] & two cases were Carpentier Edwards bioprostheses[T: C - E #31X2]. The early mortality rate[within 30 days] was 3.7%[2 patients] & the late mortality rate was 7.4%[3 patients]. Follow-up was done on 72 surviving patients; mean follow-up period was 21.17$\pm$5.36 months. Anticoagulant-related hemorrhage was observed in two patients, possible prosthetic valvular endocarditis was observed in one patient and other specific valve-related complications were none. We concluded, therefore, that good clinical results & a low complication rate could be achieved with Duromedics bileaflet valve in short-term follow-up, & long-term follow-up was also necessary.

• Journal of Chest Surgery
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• 제28권12호
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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.

• 대한산업공학회지
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• 제39권4호
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• pp.233-238
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• 2013

This article concerns a profit model in a repair limit replacement problem with imperfect repair. If a system fails, we should decide whether we repair the failed system (repair option) or replace it by new one (replacement option with a lead time). We assume that repair times are random variables and can be estimated before repair with estimation error. If the estimated repair time is less than the specified limit (repair time limit), the failed unit is repaired but the unit after repair is different from the new one (imperfect repair). Otherwise, we order a new unit to replace the failed unit. The long run average profit (expected profit rate) is used as an optimization criterion and the optimal repair time limit maximizes the expected profit rate. Some special cases are derived.

• 응용통계연구
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• 제28권4호
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• pp.763-779
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• 2015

본 연구에서는 소득계층별로 노후에 필요한 소득대체율을 추정하고 이를 달성하기 위한 연금 및 비연금 소득원의 역할 분담을 논하고 있다. 그 동안 노후소득보장 수준을 논함에 있어 노후빈곤 문제에 초점을 두다 보니 노후의 필요소득 수준에 대한 논의는 상대적으로 적었다. 이러한 관점에서 동 연구에서는 노후생활을 위한 평균적인 필요소득대체율 뿐만 아니라(전체 51.3%), 소득계층별로 필요소득대체율을 산출하고 있다(빈곤층 177.6%, 중산층 68.1%, 고소득층 29.3%). 또한 소득계층별 필요소득대체율이 현실의 실현소득대체율과 얼마나 격차가 있는 지를 살펴보았으며, 이를 통해 소득원별 역할 분담이 필요하다는 시사점을 끌어내고 있다. 즉, 목표소득대체율을 달성하기 위해 현 노인세대의 경우 연금으로만 충당하기 어려우므로 비연금 소득원을 적극 활용할 필요가 있음을 제시하였다. 한편 미래의 노인세대(현 근로세대)는 무엇보다 연금소득 마련이 중요할 것이라는 점에서 공적연금을 통한 탈빈곤, 사적연금을 통한 중산층 이상의 삶을 마련할 수 있도록 준비할 필요가 있음을 제안하고 있다.

• 한국건설순환자원학회논문집
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• 제5권4호
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• pp.450-457
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• 2017

본 연구에서는 EXFG를 활용하여 실제 현장 적용이 가능한 고품질의 바닥모르타르를 개발하고자 하였는데, 그 결과를 요약하면 다음과 같다. 먼저, ALS의 치환율이 증가할수록 플로치도 비례하게 증가하는 것으로 나타났으며, 이를 이용한 EXFG의 경우 반대로 치환율이 증가할수록 유동성은 감소하는 경향을 나타냈다. 또한, 응결시간의 경우 ALS 치환율이 5%인 배합에서는 EXFG의 치환율에 관계없이 Plain 대비 응결시간이 약 5~20% 이상 단축되는 것으로 나타났다. 압축강도의 경우 ALS 치환율 0%, 5%에서 EXFG 치환율이 1% 이내일 때 전반적으로 강도는 증가하였으며, ALS 치환율이 10% 이상일 경우에는 오히려 강도가 저하 되는 것으로 나타났다. 건초수축길이변화율의 경우 ALS 치환율 0%, 5%에서는 EXFG 치환율에 관계없이 Plain 대비 건조수축길이변화율이 약 10~25% 이상 감소하는 것으로 나타났다.

• 여성건강간호학회지
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• 제8권2호
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• pp.151-164
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• 2002

PURPOSE: Estrogen replacement therapy is indicated for the relief of hot flushes and urogenital atrophy, the prevention of osteoporosis and the reduction in risk of cardiovascular disease. The present study assessed by blood pressure, heart rate variability, and climacteric symptoms in menopausal women before treatment and at 1 month during estrogen replacement therapy. METHODS: The study sample consisted of 16 healthy menopausal women (range 49 to 59 years, mean : 53.4 years) attending menopausal clinics for the complaint of climateric symptoms at S. hospital in Chunchoen. They were all non-smokers and no patient had symptoms or evidence of cardiovascular disease. They took estrogen replacement therapy (conjugated estrogen 0.625 mg with or without medroxy progesteron 2.5mg) for 1 month. Blood pressure, heart rate variability(heart period and vagal tone) through ECG, and climacteric symptom were measured in all subjects before treatment and at 1 month during treatment. Climacteric symptom questionnaire which was developed by Neugarten et al.(1963) was modified with 20 items of question(Cronbach's alpha = 88 -.89). The data was collected from Sept. 1. 2000 to July. 30. 2001. RESULTS: There was no significant difference in mean systolic and diastolic pressure between the baseline and at 1 month during treatment. The mean heart period and vagal tone were slightly increased, but difference of mean heart period and vagal tone were not statistically significant between the baseline and at 1 month during treatment. The score of climacteric symptoms decreased significantly from the baseline after treatment. CONCLUSIONS: Even though, this study did not show that estrogen replacement therapy led decrease of blood pressure and increase heart rate variability, climacteric symptoms reduced much in all subjects after taking drugs. These results suggest that there is need to repeat study with long term period.

• 품질경영학회지
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• 제28권3호
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• pp.11-17
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• 2000

This paper presents a model for determining the optimal number of general repairs and supplementary input cost limit rate in addition to minimal repair cost rate to implement preventive maintenance. The basic concept parallels the periodic replacement model with minimal repair at failure introduced by Barlow and Hunter(1960) and Park(1979), only difference being the replacement signalled by the number of previous general repairs performed on the system. A general repair brings the state of the system to a certain better state than before repaired. Numerical examples are provided.

• 품질경영학회지
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• 제14권2호
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• pp.28-32
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• 1986

This paper studies a new replacement policy in case that average repair cost rate increases linearly in proportion to time t. At the moment when the repair cost rate reaches or exceeds a fixed level, the component is replaced. This policy is compared with the economic lifetime policy. Advantages of this model according to the increment of replacement cost is shown in numerical example.

• 대한산업공학회지
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• 제14권1호
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• pp.103-117
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• 1988

Replacement demand plays an important role to forecast the total demand of durable goods, while most of the diffusion models deal with only adoption data, namely initial purchase demand. This paper presents replacement demand forecasting models incorporating repurchase rate, multi-ownership, and dynamic product life to complement the existing diffusion models. The performance of replacement demand forecasting models are analyzed and practical guidelines for the application of the models are suggested when life distribution data or adoption data are not available.

• International Journal of Reliability and Applications
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• 제12권2호
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• pp.131-143
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• 2011

In most of literatures of age replacement policy, the authors consider the case that a new item starts operating at time zero and is to be replaced by new one at time T. It is, however, often to purchase used items because of the limited budget. In this paper, we consider age replacement policy of a used item whose age is $t_0$. The mathematical formulas of the expected cost rate per unit time are derived for both infinite-horizon case and finite-horizon case. For each case, we show that the optimal replacement age exists and is finite and investigate the effect of the age of the used item.