• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.275-280
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• 2002

To study of high volume fly -ash concrete replace cement and fine aggregate together. Proportion consideration economy cost and performance improve replacement high volume fly-ash. Experimentation study of high-strength which cement about fly-ash replacement maximum 50%Flash concrete tested slump, air contest, setting and Hardening concrete tested day of age 1, 3, 7, 28, 91 compression strength in underwater curing. Purpose of study is consultation materials in field that variety of fly ash replacement concrete mix proportion comparison and valuation.

• Journal of Korean Institute of Industrial Engineers
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• v.22 no.2
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• pp.247-253
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• 1996

This paper proposes a new two-dimensional warranty policy with replacement and repair regions and analyses the warranty cost under the new warranty policy. The product is sold under a two-dimensional warranty(usage and age) in which two regions exist : the failed product is replaced by the manufacturer in the replacement region or minimally repaired by the manufacturer in the repair region. The formula of the expected warranty cost under some assumptions about usage and failure is obtained. Numerical examples are studied.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.32
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• pp.209-220
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• 1994

In this paper, we study the timing and equipment of replacement. Those affect both available possibility and technological levels of new equipments in the future. These problems are classified according to technological levels and in consequence generated four circumstance. Models are formulated in this research. These are able to make us decision which we replace equipment at the first time. A method is suggested to find the optimal age for replacement at given each circumstance. A solution procedure and numerical example are given.

• Journal of Chest Surgery
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• v.22 no.2
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• pp.246-255
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• 1989

A total and consecutive 291 patients of isolated single mitral valve replacement using the Ionescu-Shiley bovine pericardial xenograft valve operated on between October 1978 and June 1983 were retrospectively studied for the durability of the substitute valves based on the structural degeneration of primary tissue failure which had been proved on their re-replacement surgery. The mean age at the initial surgery was 32.4*12.5 years, and the operative mortality rate was 5.2 %. The early survivors of 276 patients were followed up for a total 1148.3 patient-years[mean\ulcornerD, 4.16*2.57 years]at the follow-up end of June 1988. They experienced 4 major late complications: 1.045 % thromboembolism/patient-year [pt-yr]; 0.871 % bleeding/pt-yr; 0.610% endocarditis/pt-yr; and 3.309% overall valve failure/pt-yr or 1.655% primary tissue failure/pt-yr. The actuarial survival rates were 89.4*2.2% and 87.7*2.5% at 5 and 10 years after initial surgery respectively. The probabilities of freedom from thromboembolism were 95.1*1.6% and 93.2*2.0% at 5 and 10 years after surgery. Nineteen patients underwent re-replacement of the Ionescu-Shiley valve because of primary tissue failure, and there was no operative mortality. The incidence of primary tissue failure was highest for the patients less than 15 years of age occurring in 9 out of 27 patients [33.3 %] or 8.68 %/pt-yr, while it was 4.0 % or 0.96 %/pt-yr for the rest of patients older than this age. The probabilities of freedom from primary tissue failure were 96.7*1.4 % and 84.2*3.8% at 5 and 9 years after surgery. The freedom from tissue failure increased as the age limits of cumulative younger patients were increased while it decreased as the age limits of cumulative older patients were decreased. Although it is clear that the Ionescu-Shiley valve would degenerate prematurely in young patients, the definite age limit could not be identified when the risk of early failure was significantly high.

• The Korean Journal of Food And Nutrition
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• v.29 no.5
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• pp.643-654
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• 2016

The purpose of this study was to investigate the purchasing behavior and selection attributes for Home Meal Replacement (HMR) and to identify the selection attributes affecting purchasing frequency and purchasing costs of married women living in a city. Among 837 questionnaires distributed to HMR married women consumers, 752 complete questionnaires (89.8%) were analyzed. The younger married women group showed higher frequency of purchasing HMR than the older age group. The 20s and 30s age groups showed higher purchasing costs for HMR than the 40s and older age groups. A higher proportion of employed married women purchased HMR three or more times per week and spent an average of more than 20,000 won per purchase in comparison with unemployed married women. HMR selection attributes were classified into five factors: 'taste and sanitation', 'economic efficiency', 'health and nutrition', 'convenience', and 'reliability and awareness'; mean scores of these factors' importance levels were 4.28, 3.93, 3.59, 3.54, and 3.50 out of 5 points, respectively. The importance level of 'taste and sanitation' factor was significantly greater as married women's age decreased. However, the importance level of 'health and nutrition' factor was significantly greater as married women's age increased. The results of the logistic regression analyses indicate that the 'taste and sanitation' and 'health and nutrition' factors affected frequency of purchasing HMR. The 'reliability and awareness' factor had the most significant impact on cost per purchasing HMR. Therefore, a product differentiation strategy according to married women's age and employment status should be applied. Product qualities and brand value should be improved to enhance competition in the HMR market.

• Journal of Chest Surgery
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• v.11 no.2
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• pp.185-193
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• 1978

Between April 1976 and March 1978, six cases of tricuspid valve replacement were done in the Department of Thoracic Surgery, Seoul National University Hospital. There were 4 men and 2 women and the age of the patients ranged from 17 years of the youngest to 48 years of the oldest. Most of them had characteristic symptoms of tricuspid valve disease, such as a systolic murmur audible over the lower sternum and varying with respiration, pulsatile and distended neck vein, and an enlarged and pulsatile liver. Preoperative functional levels according to NYHA Calcification were class III in 4 cases, and class IV in 2 eases. Most of the cases showed moderate to severe cardiomegaly in chest films and elevated right atrial pressure on preoperative right heart catheterization. Five of them underwent concomittent mitral valve replacement and one pulmonary valvotomy. All of them showed tricuspid insufficiency resulted from massive dilatation of annulus, destructive lesions of valve structure, or both anomalies. One postoperative hospital death was encountered and the cause of death was low out-put syndrome. All survivors showed clinical improvement and cardiomegaly regressed and left hospital in a good condition . *Attendum; Recently 2 more cases of tricuspid valve replacement with mitral valve replacement were done after this review.

• Journal of Chest Surgery
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• v.21 no.1
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• pp.62-69
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• 1988

In the department of chest surgery of WonKwang university hospital, mechanical valve replacement was performed in 51 cases from June 1985 to September 1987. Among these, 32 cases were mitral valve replacement, 4 cases were aortic valve replacement, and 15 cases were double valve replacement. 26 cases were male and 25 cases were female and age distribution ranged from 16 years old to 63 years old. Early death within 30 days after operation was 2 cases [3.9%] and causes of death were right heart failure [1] and right ventricular wall rupture [1]. Among 49 early survivors, 2 cases of late death were developed and the causes of death were cardiomyopathy [1] and ventricular arrhythmia [1] Anticoagulant therapy was done with warfarin sodium to the level of 1.5-2 times of normal prothrombin time [20-40%] in 47 survivors. Symptomatically, 93.6% of preoperative NYHA functional class III or IV were converted to the NYHA functional class I or II during follow up.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.357-364
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• 1997

After the buyer purchases the product, the seller's role does not end. If the product fails to function properly before the end of the warranty period, the seller is responsible for its repair or replacement under the seller's warranty policy. There are two common types of warranty policies: the free replacement warranty and the rebate warranty. Under the free replacement warranty policy, replacement or repairs during the warranty period are provided by the seller free of charge to the buyer. Under the rebate warranty policy, a failed item is replaced by a new one or is repaired at a cost to the age of the failed item. The rebate warranty is most often used for items such as a battery or an automobile tire which wear out and must be replaced at failure. This paper proposes a easy way of estimating the warranty cost under the free replacement warranty policy assuming an exponential product failure function on repairable products.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.2
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• pp.93-100
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• 2013

A variety of researches on the concrete with high volume mineral admixture have increased in recent years. In fact, it is very important to find appropriate replacement ratio of concrete with high volume mineral admixture in order to apply in the field. In this study, compressive strength according to fly ash and blast furnace slag replacement ratio as well as curing temperature was measured in the conditions of obtaining the same workability in order to examine the characteristics of concrete with high volume mineral admixture. In conclusion, it was found that the compressive strength at the age of 3 days decreased by 1.4MPa and the compressive strength at the age of 28 days decreased by 3.8MPa when the fly ash replacement ratio increased by 10%. Also, it was found that the compressive strength at the age of 3 days decreased by 1.0MPa and the compressive strength at the age of 28 days decreased by 0.9MPa when the blast furnace slag replacement ratio increased by 10%. Through the tests, we obtained the basic data for developing the future research on the concrete with high volume mineral admixture for housing structure.

• IE interfaces
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• v.19 no.4
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• pp.316-323
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• 2006

In this study, based on Weibull proportional age reduction model and age replacement policy, we analyze economic life of cutting tool which allows re-grinding. Re-grinding task, usually for high-priced machining tools(e.g., broaching tool), is a kind of preventive maintenance activities to extend tool life at the completion of a lot production. The numerical results are also presented. Among the parameters of Weibull proportional age reduction model, the re-grinding effect parameter and Weibull shape parameter have a strong effect on economic tool life, and in the cost parameters, shortage cost is most sensitive. With further study on the parameter estimation of tool life process and cost function, this study can be expected to give more practical contribution to management of general machining tools.