• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.05a
• /
• pp.257-262
• /
• 2008

This study presents a detailed analysis of aircraft engine maintenance cost based on the relationships between engine performance and geometric parameters. Some trend equations based on the engine performance and maintenance database were developed for the estimation of shop-visit interval, work-scope, man-hours, material cost and Life Limited Part cost. The results show that this approach can give a more reasonable and detailed estimation of engine maintenance cost than older empirical methods.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.55 no.2
• /
• pp.61-68
• /
• 2006

Many researchers have worked for the sensorless control of SynRM in recent years. However they commonly requires large calculations which induced from its complexity. For low cost application as like home appliance, it is difficult to utilize because of the cost problem. Therefore, it is necessary to introduce simplified sensorless control scheme that is composed of least calculation to estimate the rotor position. In this paper the sensorless control is performed using the characteristics of SynRM structure in which the linkage flux varies with rotor position, so the rotor position can be detected by the change of linkage flux. The estimation of linkage flux can be acquired from the integration of the motor terminal voltage which is commonly used method for the reliability of the estimation. However this estimation method has demerits in low speed operation therefore in that region the motor terminal voltage is compensated by the phase current. A digital simulation (MATLAB) and experiment were performed to confirm the adequacy of the proposed control scheme.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2018.05a
• /
• pp.72-73
• /
• 2018

The accuracy of contingency estimation plays an important role for dealing with the uncertainty of the financial success of construction project. Its' estimation may be used for various purposes such as schedule control, emergency resolve, and quality expense, etc. This paper presents a contingency estimation method which is schedule control specific. The method 1) implements stochastic EVMS, 2) detects a specific timing for schedule compression, 3) identifies an optimal strategy for shortening planned schedule, 4) finds a probability density function (PDF) of project cost overrun, and 5) estimates the optimal contingency cost based on the level of confidence. The method facilitates expeditious decisions involved in project budgeting. The validity of the method is confirmed by performing test case.

• Journal of the Korea Society for Simulation
• /
• v.9 no.4
• /
• pp.67-75
• /
• 2000

Often system analysts are interested in the estimation of percentile for system performance. For instance, in PERT network system, the percentile that the project. Typically the control variate method is used to reduce the variability of mean response using the correlation between the response and the control variates with a little additional cost during the course of simulation. In the same spirit, we apply this method to estimate the percentile of project completion time in PERT system, and evaluate the efficiency of the controlled estimator for its percentile.1 Simulation results indicate that the controlled estimators are more effective in reducing the variances of estimators than the simple estimators, however those tend to a little underestimate the percentiles for some critical values. We need more simulation experiments to examine such a kind of bias problem. We expect this research presents a step forward in the area of variance reduction techniques of stochastic simulation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.15 no.12
• /
• pp.1028-1034
• /
• 2003

The objectives of this paper are to study the effect of key parameters on the cycle performance and capacity and to estimate the cost of latent and sensible energy transportation systems. The overall conductance (UA) of each component, the ambient temperature and the absorber inlet temperature are considered the key parameters. It is concluded that COP of the solution transportation using an absorption system (STA) at ambient temperature is 10% higher than that of the conventional sensible system. It is also found that the cost of STA system can be reduced 7.5 times to that of sensible energy transportation for one year of operation with 10 km transportation distance.

• Journal of the Korea Society for Simulation
• /
• v.29 no.4
• /
• pp.85-94
• /
• 2020

In determining the feasibility of planning and launching railway transportation projects, various decision-making processes are essentially required. LCC(Life Cycle Cost) value including total construction cost and operation cost is estimated in approximation Model with rough guideline. In this study, modeling and simulation-based analysis method is proposed to support the decision making process of railroad transportation and derivation of LCC. Firstly, cost analysis model was constructed by collecting various existing rail transportation business data to enable analyze based on numerical data, and the result were analyzed by DOE(Design Of Experiments) and RSM (Response Surface Method) simulation. Professional commercial software tools were used for effective model construction and simulation. In order to verify the research results, the actual railroad transportation projects were selected, and the results of the analysis were compared.

• Journal of the Korean Data and Information Science Society
• /
• v.20 no.5
• /
• pp.887-894
• /
• 2009

The two-stage minimum risk point estimation of mean, the probability of success in a sequence of Bernoulli trials, is considered for the case where loss is taken to be symmetrized relative squared error of estimation, plus a fixed cost per observation. First order asymptotic expansions are obtained for large sample properties of two-stage procedure. Monte Carlo simulation is carried out to obtain the expected sample size that minimizes the risk and to examine its finite sample behavior.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2012.05a
• /
• pp.161-163
• /
• 2012

Recently on Value Engineering(VE) and Life Cycle Cost(LCC) social interests is increasing. The government Turn Key, BTL projects and public works projects, such as VE and LCC Analysis on the value and economic analysis is mandatory. And accordingly the VE and LCC analysis is underway for the various studies. However, there is a problem existing in the LCC analysis. Worth the cost varies according to the flow of time. However, the real interest rate during the LCC analysis of buildings in calculation time for interest rates and inflation are not considering the value of the flow. In other words, a few years using the average value of the deterministic analysis method has been adopted. These costs for the definitive analysis of the cost of an uncertain future, unforeseen changes resulting hazardous value. In this study of the last 15 years interest rates and inflation targeting by using Monte-Carlo Simulation is to perform probabilistic analysis. This potential to overcome uncertainties of the cost of building a more scientific and LCC Estimation of the probability value of the real interest rate is presented.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.9
• /
• pp.2403-2413
• /
• 1999

There is a strong need to develop a software cost estimation model on economic value perspective. The objective of this research is to improve current software cost estimation method on economic value perspective. We reviewed domestic and foreign researches and practices on software cost estimation with function point method, and derived promising alternative models. Pilot simulation was performed with real project data, and the probable best model was chosen. We collected data from 39 Korean companies, and assesed statistical significance of the model with those data. Empirical data shows that more practical model has better prediction accuracy. That is, the number of input and output modules, the number of tables, and the number of algorithms are chosen to be best set of functions. There exists strong correlation between the calculated function points and project effort. And, the revised set of technical complexity factors and evaluation guidelines show practical usefulness. We suggest that the above result be incorporated in a new improved guideline for software cost estimation. By adopting the results of this research to the guideline, we expect that technology innovation will be expedited, and that overall productivity of software industry will be increased.

• Korean Journal of Construction Engineering and Management
• /
• v.21 no.6
• /
• pp.113-124
• /
• 2020

Social movements to improve the performance of buildings through remodeling of aging apartment houses are being captured. To this end, the remodeling construction cost analysis, structural analysis, and political institutional review have been conducted to suggest ways to activate the remodeling. However, although the method of analyzing construction cost for remodeling apartment houses is currently being proposed for research purposes, there are limitations in practical application possibilities. Specifically, In order to be used practically, it is applicable to cases that have already been completed or in progress, but cases that will occur in the future are also used for construction cost analysis, so the sustainability of the analysis method is lacking. For the purpose of this, we would like to suggest an automated estimating method. For the sustainability of construction cost estimates, Deep-Learning was introduced in the estimating procedure. Specifically, a method for automatically finding the relationship between design elements, work types, and cost increase factors that can occur in apartment remodeling was presented. In addition, Monte Carlo Simulation was included in the estimation procedure to compensate for the lack of uncertainty, which is the inherent limitation of the Deep Learning-based estimation. In order to present higher accuracy as cases are accumulated, a method of calculating higher accuracy by comparing the estimate result with the existing accumulated data was also suggested. In order to validate the sustainability of the automated estimates proposed in this study, 13 cases of learning procedures and an additional 2 cases of cumulative procedures were performed. As a result, a new construction cost estimating procedure was automatically presented that reflects the characteristics of the two additional projects. In this study, the method of estimate estimate was used using 15 cases, If the cases are accumulated and reflected, the effect of this study is expected to increase.