• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.8
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• pp.600-605
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• 2014

Two mufflers for a large-size sedan are suggested aiming (1) sporty-sound and (2) quiet-sound as well as both satisfying low back-pressure and low manufacturing cost. Transmission loss prediction considering heat and flow may increase the accuracy and reduce the development cost in muffler design; thus, GT-power prediction considering heat, flow, and acoustics is utilized. By understanding the fundamentals of flow-acoustic theory in small orifice(hole), an effective muffler design concept is proposed. Vehicle tests show the consistence with predictions for sound; also a back-pressure test bench confirms the advantage in pressure drop for both suggested mufflers. Those suggested mufflers also have advantages in manufacturing cost due to simplicity of the design.

• Journal of Energy Engineering
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• v.17 no.3
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• pp.139-144
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• 2008

Recently due to march as the high oil price, It is necessary for Korea to grope a plan, which is to increase the energy efficiency of existing facilities as well as to develop overseas gas and oil resources. With this point, this work carried out to approach the high pressure LNG pipeline network of Inchon receiving terminal with Newton method as corrective flowrate. We found that the high pressure network mainly depends on FCVs(Flow Control Valves). The high pressure pump showed the maximum efficiency at the FCVs of 50% opening and could discharge LNG only above the LNG head of 1,500m from a system curve obtained. The operating cost of pumps was estimated from their operating points. We compared the operating cost under normal operation with the operating cost under maximum efficiency. Especially, we obtained the day savings of a year as wells as the hour savings of a day. From the results, the high pressure network win be able to reduce the operating cost of 138 million wons in a year. This means that a pump can reduce the operating cost of 9,823 thousands won. Consequently, this work could find the operating features of the pumps under the complicated high pressure LNG network and the savings effect of the pump operating cost. Also, the results will be able to macroscopically contribute the heightening of national energy competitiveness as well as to microscopically contribute the future effective operation of LNG receiving terminal.

• Geomechanics and Engineering
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• v.28 no.1
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• pp.65-75
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• 2022

Time and cost of construction are key factors in decision-making during a tunnel project's planning and design phase. Estimations of time and cost of tunnel construction projects are subject to significant uncertainties caused by uncertain geotechnical and geological conditions. The Gaussian Process Regression (GPR) technique for predicting ground condition and construction time and cost of mountain tunnel projects is used in this work. The GPR model is trained with data from past mountain tunnel projects. The model is applied to a case study in which the predicted time and cost of tunnel construction using the GPR model are compared with the actual construction time and cost for model validation and reducing the uncertainty for the future projects. In addition, the results obtained from the GPR have been compared with to other models of artificial neural network (ANN) and support vector regression (SVR) that the GPR model provides more accurate results.

• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.275-287
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• 2017

During the feasibility study of new rail lines, maintenance cost of railway infrastructure has mostly been estimated based on the track length and on simplified parameters; however, the estimation reliability can be improved by employing the correction factor from UIC 715, as well as the line classification in UIC 714. The correlations between maintenance cost and various parameters such as weighted track length based on line classification, radius of curvature, gradient and worn -out rate have been analyzed according to the case studies. Prediction of the maintenance cost has been carried out using the cost data, which were representative of the whole cost data; as a result, it was demonstrated that a cost model based on the line classification and the correction factor was more reliable than the existing models. Furthermore, possibilities of using data from both the track measurement vehicle and from the maintenance information system, which are under development, have been investigated and, based on this investigation, a combined cost model using line classification, radius of curvature, gradient and worn-out rate, among other factors, will be proposed in the near future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.128-134
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• 2016

Estimating the repair and reinforcement (R&R) costs for each bridge member is essential for managing the life cycle of a bridge using a bridge management system (BMS). Representative members of a bridge were defined in this study, and detailed and representative R&R methods for each one were drawn in order to develop a systematic maintenance cost model that is applicable to the BMS. The unit cost for each detailed R&R method was established using the standard of estimate and historical cost data, and a systematic procedure is presented using an integration program to enable easy renewal of the R&R unit cost. Also, the average unit cost of the representative R&R methods was calculated in the form of a weighted average by considering the unit cost and application frequency of each detained R&R method. The appropriateness of the drawn average unit cost was reviewed by comparing and verifying it with the previous historical unit cost. The suggested average R&R unit cost can be used to review the validity of the required budget or the appropriateness of the R&R performance cost in the stage to establish the bridge maintenance plan. The results of this study are expected to improve the reliability of maintenance cost information and the rationality of decision making.

• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.65-71
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• 2009

In this study, performance and economic analysis of natural gas/syngas fueled 100 MWth chemical-looping combustion (CLC) combined cycle plant were performed. Net efficiency of both cases was 53~54%, corresponding to previous research. We used Chemical Engineering Plant Cost Index and Guthrie method to evaluate plant cost. For syngas fueled CLC combined cycle plant, the plant cost was higher since lower heating value(LHV) of syngas was lower than that of natural gas and cost of electricity(COE) was also higher since the cost of syngas was higher than that of natural gas. By sensitivity analysis, it was shown that the cost of syngas should be less than 5.3 $/GJ in order to make COE lower than 5.8 ¢/kWh which was COE of natural gas fueled CLC combined cycle plant.

• IE interfaces
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• v.20 no.3
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• pp.395-406
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• 2007

In the telecommunication industry, estimation of the cost of network facilities is very important since depreciation cost of the facilities accounts for a large portion of the product cost. Moreover, cost estimation in the industry becomes more difficult because of increasing indirect cost upon digital convergence, expanding multi-purpose facilities, complexity of service product, etc. Nevertheless, not much seem to have been done in improving estimation methodology of the cost of network facilities. As a result, the quality of cost information on network facilities has deteriorated, and now even decision-makers in the industry dismiss the information. Recently, two major telecommunication companies adopted a new network cost estimation method to deal with the issue. In this paper, we study the concept of new cost estimation method and the procedure to develop and apply it. We also suggest the method to carry out the cost allocation using Matlab which is more efficient and time-saving than other commercial cost calculation packages.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.10
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• pp.1390-1396
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• 2013

The paper estimated the reasonable market price of lead-acid battery energy storage system (BESS) intended for demand management of electricity customers. As time-of-use (TOU) tariffs have extended to a larger number of customers and gaps in the peak and off-peak rates have gradually risen, deployment of BESS has been highly needed. However, immature engineering techniques, lack of field experiences and high initial investment cost have been barriers to opening up ESS markets. This paper assessed electricity cost that BESS operation could save for customers and, based on the possible cost savings, estimated reasonable prices at which BESSs could become a more prospective option for demand management of customers. Battery scheduling was optimized to maximize the electricity cost savings that BESS would possibly achieve under TOU tariffs conditions. Basic economic factors such as payback period and return on investment were calculated to determine reasonable market prices. Actual load data of 12 industrial customers were used for case studies.

• Journal of Gastric Cancer
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• v.12 no.2
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• pp.126-131
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• 2012

Purpose: We developed a standardized critical pathway for gastric cancer surgery and then determined the increase of application, which resulted in an improvement in terms of measurable indices, such as hospital stay and cost. Materials and Methods: A critical pathway was revised and used widely from the 2nd quarter of 2009. We collected clinical data, such as length of stay and complication rate, as clinical indices of quality prospectively. The total cost paid at the patient's discharge, as well as the daily hospital income, were calculated and compared by each quarter from January 2008 to December 2009. Results: The application rate of critical pathway was 11.8% and 87.8% in 2008 and 2009, respectively. There were no perioperative deaths. There was no difference in the complication rates between 2008 and 2009 (P=0.45). However, the mean length of stay was significantly different between the 2 years (P<0.05). Although the total cost was not different, the daily hospital income was significantly higher in the latter year (P<0.05). Conclusions: An increase in the application of critical pathway for gastrectomy resulted in significant decreases in length of stay and increases in the daily hospital income without a compromise on the clinical indices.

• Korean Journal of Construction Engineering and Management
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• v.22 no.2
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• pp.42-52
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• 2021

The cost of remodeling parking lots of apartment houses accounts for about 20 percent of the total cost of remodeling. This means that when the remodeling cost of the underground parking lot is known, it becomes possible to estimate the total construction cost. The standard of estimation referenced when calculating the construction cost is difficult to apply to calculating the remodeling cost. Thus, a construction cost estimation model that reflects the characteristics of remodeling construction is necessary. This study developed a basic construction cost estimation model for expansion remodeling of underground parking lots of apartment houses that calculates the approximate cost of construction by reflecting the characteristics and design elements of remodeling. Based on literature review and consultation with experts, 37 activities of underground parking lot remodeling construction were derived. In order to enable calculation of approximate construction cost before the remodeling design drawing is finalized, the quantity calculation formula and unit price for each activity were presented. Based on expert advice, 13 factors that affect the increase in construction cost and weights of each factor were determined. As a result of applying three cases of remodeling complexes to the basic cost estimation model, the accuracy was confirmed to be 93 percent on average.