• International Journal of Reliability and Applications
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• v.12 no.2
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• pp.117-122
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• 2011

In this paper, we suggest the optimal replacement policy following the expiration of repair warranty when the cost of minimal repair depends on the age of system. To do so, we first explain the replacement model under repair warranty. And then the optimal replacement policy following the expiration of repair warranty is discussed from the user's point of view. The criterion used to determine the optimality of the replacement model is the expected cost rate per unit time, which is obtained from the expected cycle length and the expected total cost for our replacement model. The numerical examples are given for illustrative purpose.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.59
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• pp.97-103
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• 2000

This study considers the design of life test sampling inspection plans by attributes for failure rate level qualification at selected confidence level. The lifetime distribution of products is assumed to be exponential. MIL-STD-690C and KS C 6032 standards provide this procedures. But these procedures have some questions to apply in the field. The cost of test and confidence level($1-{\beta}$ risk) are the problem between supplier and user. So, we suggest that the optimal life test sampling inspection plans using expected cost model considering product cost, capability, environmental test cost, etc.

• Proceedings of the Korean Statistical Society Conference
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• 2005.11a
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• pp.73-78
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• 2005

This paper considers a preventive maintenance policy following the expiration of renewing warranty, Most preventive maintenance models assume that each PM costs a fixed predetermined amount regardless of the effectiveness of each PM. However, it seems more reasonable to assume that the PM cost depends on the degree of effectiveness of the PM activity. In this paper we consider a periodic preventive maintenance policy following the expiration of renewing warranty when the PM cost is an increasing function of the PM effect. The optimal number and period for the periodic PM policy with effect dependent cost that minimize the expected cost rate per unit time over an infinite time span are obtained.

• Current Research on Agriculture and Life Sciences
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• v.32 no.4
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• pp.231-235
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• 2014

This study performed a benefit cost analysis of an automatic eggshell crack detection system. Based on various cost benefit analysis methods, including the net present value (NPV), internal rate of return (IRR), and benefit cost ratio (B/C Ratio), the automatic eggshell crack detection system was confirmed to have economic validity. The NPVs were 175,035,645 won at a 5% discount rate and 129,082,393 won at a 10% discount rate. Plus, the IRRs were 0.686 at a 5% discount rate and 0.660 at a 10% discount rate. Finally, the B/C ratios were 1.981 at a 5% discount rate and 1.900 at a 10% discount rate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1346-1352
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• 2009

Warranty cost of automobile parts varies depending on the parts failure rate in a warranty region of individual markets. Parts failure rate is significantly affected by usage-rate given that other stressors of individual markets are similar. Accordingly, warranty cost can be predicted by failure modeling which reflects usage-rate and using a stochastic process. In this paper, one-dimensional approach is used by applying accelerated failure time model on the assumption that the usage-rate is linear. Such model can explain changes in parts failure rate depending on the changes in usage-rate since it can be expressed as a function of usage-rate. Therefore, acquisition of usage-rate in a new market will automatically lead to estimate of failure rate even without warranty data and warranty cost of parts can be predicted through a renewal process in replacement cases. A case study using warranty data of two real markets is presented in the application part of this paper.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.921-926
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• 2006

The present study has been conducted economic analysis through actual operation of EHP and GHP which are installed at the same building of an university Cost items, such as initial cost, annual energy cost and maintenance cost of each system are considered to analyze LCC and economical efficiency is compared. The initial cost is considered on the basis of actual costs, and annual energy cost is converted into the cost after measuring electricity and gas consumption a day. LCC applied present value method is used to assess economical efficiency of both them. Variables used to LCC analysis are electricity cost escalation rate, natural gas cost escalation rate, interest rate, and service lives and when each of them are 4%, 2%, 8%, and 20 years, results of analysis short that EHP(148,257,306 won) is 8.05%(12,981,990 won) more profitable than GHP(161,239,295 won).

• International Journal of Highway Engineering
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• v.8 no.2 s.28
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• pp.49-54
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• 2006

The purpose of this study was to determine the effect of expansion joint spacing (slab size) on the life cycle costs of owning Portland Cement Concrete (PCC) airfield pavements. Previous research has shown that slab size has a statistically significant impact on pavement performance. A probabilistic life cycle cost analysis was performed to determine if the effect of slab size on pavement performance would affect the total cost of ownership of PCC pavements. Data from 48 Pavement Condition Index (PCI) inspections of military and civilian airfields were used to develop probability-of-distress-by-condition curves, which were then used to develop probabilistic cost-of-repair-by-condition curves. A present worth life cycle cost analysis was then performed for various slab sizes, using construction costs, rehabilitation costs, and maintenance costs. Maintenance costs were determined by assuming a condition deterioration rate appropriate for each slab size and applying the cost-by-condition curves. The probabilistic cost-of-repair-by-condition curves indicated that smaller slabs are more expensive to repair on a unit cost basis. Life cycle cost analysis showed that larger slabs have a higher total cost of ownership than smaller slabs due to a faster rate of deterioration.

• Journal of the Korea Institute of Building Construction
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• v.14 no.5
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• pp.415-422
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• 2014

There is growing difference between a planned value and an actual cost for increasing as an risk of construction cost. A construction cost index is an alternative to redeem a problem, but it is still very difficult to reduce an actual differential as a price fluctuation. Furthermore an existing theory of a construction cost index is overly complex, and is unsuitable for using in working-level. This study suggests an optimum correction rate in respect of a total construction cost. It is analyzing the actual cost of 53 public buildings that the Public Procurement Service ordered. The objects are main processes that include architectural works, mechanical works, electrical works, telecommunication works, and service facilities. It is compared a total construction cost based on absolute error rate using the median from frequentist principle. For this, it is selected the suitable regression model and set a correction rate.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.6
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• pp.451-458
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• 2014

The purpose of this study is to compare the economics between a diesel propulsion vessel and a LNG fuel propulsion vessel through the analysis of the present value using the LCC(Life Cycle Cost) method. This study is also to judge the economics for long-term operation of a LNG fuel propulsion vessel as a result of analysis about the equivalent uniform annual cost. In particular, LCC method was strengthened by sensitivity analysis based on combined interest rate which is considering discount rate and inflation rate simultaneously.

• Journal of Korean Society for Quality Management
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• v.46 no.4
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• pp.797-820
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• 2018

Purpose: It is to seek for an appropriate cost rate analysis methodology of credit card value propositions in Korea. For this issue, it is claimed that methodologies based on probability distribution is more suitable than methodologies based on data-mining. The analysis model constructed for the cost rate estimation is called VCPM model. Methods: The model includes two major variables denoted as S and P. S is monthly credit card usage amount. P stands for the proportion of usage amount at special merchants over the whole monthly usage amount. The distributions assumed for P are positively skewed distributions such as exponential, gamma and lognormal. The major inputs to the model are also derived from S and P, which are E(S) and the aggregate proportion of usage amount at special merchants over the total monthly usage amount. Results: When the credit card's value proposition is general discount, the VCPM model fits well and generates reasonable cost rate(denoted as R). However, it seems that the model does not work well for other types of credit cards. Conclusion: The VCPM model is reliable for calculating cost rate for credit cards with positively skewed distribution of P, which are general discount card. However, another model should be built for cards with other types of distributions of P.