• International conference on construction engineering and project management
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• 2007.03a
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• pp.30-40
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• 2007

The demand for light-rail construction projects has recently been increasing, and they are mostly supervised by private construction companies. Therefore, a private construction company that aim to raise gains from the operation of the facilities during the contract period greater than what they invested should b able to accurately calculate the costs from the aspect of Life Cycle Cost (LCC). In particular, a light-rail transit bridge that has a heavier portion from the aspect of the cost of light-rail transit construction requires a more accurate calculation method than the conventional LCC calculation method. For this, an LCC analysis model was developed and a cost breakdown structure was suggested based on literature review. The construction costs by shape of the upper part of a light-rail transit were calculated based on the cost breakdown system presented in this paper, and the cost generation cycle and cost unit price were collected and analyzed based on records on maintenance costs, rehabilitation and replacement. In addition, after forming some hypotheses in order to perform the LCC analysis, economic evaluation was conducted from the aspect of the LCC by using performance data by item.

• Journal of Korean Society for Quality Management
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• v.31 no.1
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• pp.142-147
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• 2003

Burn-in is a widely used method to eliminate the initial failures. Preventive maintenance policy such as block replacement with minimal repair at failure is often used in field operation. In this, paper burn-in and maintenance policy are taken into consideration at the same time. The cost of a minimal repair is assumed to be a non-decreasing function of its age. The problems of determining optimal burn-in times and optimal maintenance policy are considered.

• International Journal of Quality Innovation
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• v.7 no.3
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• pp.15-23
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• 2006

A spare ordering policy is considered for planned maintenance. Introducing the ordering, uptime, downtime, inventory costs and salvage value, we derive the expected cost effectiveness. The problem is to determine jointly the ordering time for a spare and the preventive replacement time for the operating unit which maximize the expected cost effectiveness. Some properties regarding the optimal policy are derived, and a numerical example is included to explain the proposed model.

• Journal of Korean Society for Quality Management
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• v.14 no.1
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• pp.61-66
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• 1986

Many papers have suggested various models how to decide an optimal time for replacing equipment. In this study, Dynamic Programming is applied to establish a model of replacing equipment and a new algorithm is developed for computerization to meet the increased number of variables. It is possible to predict the real situation with higher accuracy by employing the proposed model including more variables such as planning horizon, original cost, salvage value, decreasing rate, operating and maintenance costs, increasing rate, and so on.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.10-12
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• 2002

사용자의 요구와 인터넷 어플리케이션의 발달로 규모가 큰 미디어 오브젝트의 수가 급증하고 있다. 따라서 네트워크 전송비용은 반드시 고려해야 하는 중요한 요소이다. 본 논문에서는 기존 프락시 캐시 교체 정책들을 분석하고, 이를 개선한 G-N 및 L-N 정책을 제안한다. 이것은 프락시 캐시 소프트웨어인 'Squid'에서 채택하고있는 GDSF와 LFU-DA 정책에 네트워크 전송 비용을 추가하여 확장한 알고리즘이다. 시뮬레이션을 통하여 기존의 알고리즘과 비교해 본 결과, 평균 응답 시간을 10%이상 감소시킬 수 있었으며, 추가로 드는 비용(Processing Overhead)은 3게 증가하지 아니 하였음을 확인하였다.

• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.147-151
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• 2002

Burn-in is a widely used method to eliminate initial failures. Preventive maintenance policy such as block replacement with minimal repair at failure is often used in field operation. In this paper burn-in and maintenance policy are taken into consideration at the same time. The cost of a minimal repair is assumed to be a non-decreasing function of its age. The problems of determining optimal burn-in times and optimal maintenance policy are considered.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.11 no.17
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• pp.55-65
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• 1988

This article suggests the costs analysis of resumer's view under the stepdown warranty is renewd whenever a failure occurs in the warranty period. And the general warranty policy is showed such as free replacement policy prorata warranty policy, hybrid warranty policy. In this respect case, the cost of consumer is also calculated. In order to study the cost analysis of consumer. "RENEWAL THEORY" is introduced and the cost of consumer is calculated.alculated.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.10
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• pp.1443-1451
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• 2014

Increasing cost and scarcity of maize has stimulated the use of alternative feed sources (AFS) in the diets of cattle. In this study, we investigated the effects of partial or total replacement of maize on nutrient digestibility, growth performance, blood metabolites, and economics in Limousin crossbred feedlot cattle. Forty-five $Limousin{\times}Luxi$ crossbred bulls were randomly assigned to the three treatment groups, orthodox diet (OD; 45.0% maize), partial replacement diet (PRD; 15% maize, 67% AFS), total replacement diet (TRD; 0% maize, 100% AFS). The growth feeding trial lasted for 98 days. Dry matter intake (DMI) and average daily gain (ADG) were recorded. The digestion trial was carried out after the end of the growth trial. Total faeces and feed samples were measured daily. Digestibilities of dry matter (DM) and organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were calculated. After the feeding trial, blood metabolites were measured in 12 animals from each group. Initial and final body weights did not differ significantly among treatment groups (p>0.05). The ADG and DMI were 1.72 and 8.66, 1.60 and 9.10, and 1.40 and 9.11 kg/d for OD, PRD, and TRD, respectively. The PRD and TRD exhibited lower ADG (p<0.01) and higher DMI (p<0.01) than OD. The DMI (%body weight) was comparable between groups (p>0.5). Feed efficiency of PRD and TRD were lower than OD (p<0.01). The DM digestibility decreased with reduced level of maize (p = 0.10), OM digestibility was higher in OD (p<0.05), and CP, NDF and ADF digestibilities were similar for all groups (p>0.05). Blood urea nitrogen (mg/dL) in PRD and TRD was higher than OD (p<0.01), while other blood parameters did not differ significantly. Feed costs ($/head/d) were 1.49, 0.98, and 0.72 for OD, PRD, and TRD, respectively (p<0.01). Feed costs per kg gain ($) were significantly lower for PRD (0.63) and TRD (0.54) than OD (0.89; p<0.01). Overall profit ($/head) and daily profit ($/head/d) did not differ significantly between treatments (p>0.05), although TRD showed the highest economic benefits overall (p<0.01). While a traditional diet maximized the growth rate, partial or total replacement of dietary maize with AFS proved economically feasible due to their lower costs and comparable nutrient digestibilities of DM, CP, NDF, and ADF. Partial replacement may prove economically competitive in the current situation of China.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.6
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• pp.543-556
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• 2009

Recently, NAND flash memory is being used as the swap device of virtual memory as well as the file storage of mobile systems. Since temporal locality is dominant in page references of virtual memory, LRU and its approximated CLOCK algorithms are widely used. However, cost of a write operation in flash memory is much larger than that of a read operation, and thus a page replacement algorithm should consider this factor. This paper analyzes virtual memory read/write reference patterns individually, and observes the ranking inversion problem of temporal locality in write references which is not observed in read references. With this observation, we present a new page replacement algorithm considering write frequency as well as temporal locality in estimating write reference behaviors. This new algorithm dynamically allocates memory space to read/write operations based on their reference patterns and I/O costs. Though the algorithm has no external parameter to tune, it supports optimized implementations for virtual memory systems, and also performs 20-66% better than CLOCK, CAR, and CFLRU algorithms.

• Journal of Korean Society for Quality Management
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• v.52 no.1
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• pp.43-56
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• 2024

Purpose: The injection molding process, crucial for plastic shaping, encounters difficulties in sustaining product quality when replacing injection machines. Variations in machine types and outputs between different production lines or factories increase the risk of quality deterioration. In response, the study aims to develop a system that optimally adjusts conditions during the replacement of injection machines linked to molds. Methods: Utilizing a dataset of 12 injection process variables and 52 corresponding sensor variables, a predictive model is crafted using Decision Tree, Random Forest, and XGBoost. Model evaluation is conducted using an 80% training data and a 20% test data split. The dependent variable, classified into five characteristics based on temperature and pressure, guides the prediction model. Bayesian optimization, integrated into the selected model, determines optimal values for process variables during the replacement of injection machines. The iterative convergence of sensor prediction values to the optimum range is visually confirmed, aligning them with the target range. Experimental results validate the proposed approach. Results: Post-experiment analysis indicates the superiority of the XGBoost model across all five characteristics, achieving a combined high performance of 0.81 and a Mean Absolute Error (MAE) of 0.77. The study introduces a method for optimizing initial conditions in the injection process during machine replacement, utilizing Bayesian optimization. This streamlined approach reduces both time and costs, thereby enhancing process efficiency. Conclusion: This research contributes practical insights to the optimization literature, offering valuable guidance for industries seeking streamlined and cost-effective methods for machine replacement in injection molding.