• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.1
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• pp.110-117
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• 2018

Machines and facilities are physically or chemically degenerated by continuous usage. One of the results of this degeneration is the process mean shift. By the result of degeneration, non-conforming products and malfunction of machine occur. Therefore a periodic preventive resetting the process is necessary. This type of preventive action is called 'preventive maintenance policy.' Preventive maintenance presupposes that the preventive (resetting the process) cost is smaller than the cost of failure caused by the malfunction of machine. The process mean shift problem is a field of preventive maintenance. This field deals the interrelationship between the quality cost and the process resetting cost before machine breaks down. Quality cost is the sum of the non-conforming item cost and quality loss cost. Quality loss cost is due to the deviation between the quality characteristics from the target value. Under the process mean shift, the quality cost is increasing continuously whereas the process resetting cost is constant value. The objective function is total costs per unit wear, the decision variables are the wear limit (resetting period) and the initial process mean. Comparing the previous studies, we set the process variance as an increasing concave function and set the quality loss function as Cpm+ simultaneously. In the Cpm+, loss function has different cost coefficients according to the direction of the quality characteristics from target value. A numerical example is presented.

• Journal of the Korean Solar Energy Society
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• v.22 no.4
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• pp.97-106
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• 2002

The purpose of this study is to analyze the life cycle cost of primary cooling system by systematic support cost. Life Cycle Cost(LCC) is the process of making an economic assessment of an item, area, system, or facility by considering all significant costs of ownership over an economic life, expressed in terms of equivalent costs. The essence of life cycle costing is the analysis of equivalent costs of various alternative proposals. In order to select economical primary cooling system in early heat source plan stages, the research investigates cost items and cost characteristics during project process phases such as planning/design, construction, maintenance /management, and demolition/sell phases. The study also analyze the life cycle cost by capacity leading to suggest the most economical primary cooling system by systematic support cost.

• Korean Journal of Construction Engineering and Management
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• v.9 no.6
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• pp.235-243
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• 2008

Construction projects have unique characteristics that these may be carried out by contractors thus, cost should be estimated before execution. The importance of cost estimation and cost check has become increasingly emphasized in all phases of construction project that would be performed numerously. It is needed that owner have to estimate reasonable budget, and contractor should predict the bid price. However, there are lack of standard cost estimation method before quantity takeoff, cost analysis method, and cost database thus, the method of area cost, such as square foot method, is as used as ever in Korea. Therefore, this research suggested standard cost database structure CUBE, and analysis method of item quantity per one household categorized by area type. Whereafter, database of all item quantity of finish work has been built with 90 building cost data, and validated it's availability. In this respect, the suggested method and the findings from this research are expected to help enhancing the efficiency and productivity of cost estimation in Korea.

• Journal of Korean Society for Quality Management
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• v.11 no.1
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• pp.10-17
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• 1983

This paper studies item-life test plans with the specified item mean life $T_1$ (MTBF) - Producer's risk ${\alpha}$ and item mean life $T_2$ (MTBF, $T_2$ < $T_1$) - Consumer's risk ${\beta}$ when the probability of item survival follows the Weibull distribution (known shape parameter) as a expansion of [1]. And Operating Characteristic Curves and Average Life-testing Times of item-life test plans are computed for this paper and [1]. Cost analysis procedures are same as [1]. These results are computed by using computer program written in Level II Basic for Apple II Plus Micro-computer. Both this paper and [6] reduce the life-testing time for Weibull distribution in comparision with Exponential distribution, but results of [6] were computed for different criterions from this paper.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.10
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• pp.1010-1014
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• 2010

Article-related product recommender system is an emerging e-commerce service which recommends items based on association in contexts between items and articles. Current services recommend based on the similarity between tags of articles and items, which is deficient not only due to the high cost in manual tagging but also low accuracies in recommendation. As a component of novel article-related item recommender system, we propose a new method for tagging item images based on pre-defined categories. We suggest a hypernetwork-based algorithm for learning association between images, which is represented by visual words, and categories of products. Learned hypernetwork are used to assign multiple tags to unlabeled item images. We show the ability of our method with a product set of real-world online shopping-mall including 1,251 product images with 10 categories. Experimental results not only show that the proposed method has competitive tagging performance compared with other classifiers but also present that the proposed multi-tagging method based on hypernetworks improves the accuracy of tagging.

• Journal of Korean Dental Hygiene Science
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• v.3 no.2
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• pp.1-8
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• 2020

This study investigated the relationship between oral health knowledge, behavior and orthodontic satisfaction in orthodontic patients visiting dental hospitals and clinics and provided suggestions to improve orthodontic patients' satisfaction. This study anayzed structured self-administered questionnaires collected from 245 patients who visited 5 dental clinics in Gwangju Metropolitan City. Regarding oral health knowledge, the highest percentage of correct answers was for the item "Cavities heal themselves over time" (97.1%), and the lowest percentage of correct answers was for the item "Cavity bacteria move from tooth to tooth" (16.7%). Five fluoride items showed a lower percentage of correct answers than those for cavity and gingival diseases. Regarding the survey on oral health behavior, the highest score was found for the item "I brush my teeth with a certain method and order" (3.78 out of 5), and the lowest score was found for the item "I use an electric toothbrush" (1.34 out of 5). Regarding the survey on orthodontic satisfaction, the highest score was found for the item "I would recommend receiving medical treatment at the department of orthodontics" (4.23), and the lowest score was found for the item "Orthodontic cost is reasonable" (3.46). While oral health behavior had on orthodontic satisfaction, oral health knowledge had no effect on it. Oral health behaviors should be improved to enhance orthodontic satisfaction. To improve oral health behavior, it is necessary to develop and activate education programs for tooth brushing and oral care for orthodontic patients.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.711-720
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• 2007

Apartment housing in the Korean domestic construction industry has had various and high-quality finishing work since the enforcement of price deregulation in 1998. Before the enforcement of price deregulation, feasibility studies of housing projects have not had particular difficulties as uniform description of finishing work items were reflected and finishing work cost also was equalized. However, the recent distinction of finishing work based on the same floor plan brings about project cost variation, along with many effects on construction management due to project cost increment. Accordingly, this paper suggests the improved plan of cost management to control the feasibility study result consistently during the life cycle of a project through an analysis based on cost management phase due to cost blackout, appearing at the commencement of a project, cost gradation caused by high-quality finishing work item, and cost reduction due to the degradation of finishing work after analysis of current apartment construction process focused on finishing work using the IDEF process analysis technique.

• 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.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.745-752
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• 2024

This paper presents a study that compares and analyzes the practices of utilizing BIM (Building Information Modeling) for construction cost estimation in Japan and China. The study delves into the nuanced differences and similarities in cost estimation methodologies between the two countries. The overview section explored their respective standard specifications, and the methodologies for construction quantities take-off, covering both the bottom-up estimating approach and the all-in unit rate approach. Additionally, the paper delves into the item code system used in BQ (Bills of Quantities), elaborating on its introduction and practical application. The paper meticulously breaks down the process of quantities take-off facilitated by BIM models and cost-estimating software. The study also delves into the developmental trends in comprehensive BIM standards about construction cost, coupled with the proposition of a BIM code for seamless integration into construction cost practices as part of a forward-looking research plan. In conclusion, the paper encapsulates the comparative findings, highlighting the strengths, weaknesses, and potential areas for improvement in the BIM-enabled construction cost estimation practices of Japan and China. This study contributes to a deeper understanding of the utilization of BIM technology in the construction industry, offering valuable insights for practitioners, researchers, and policymakers alike.

• Journal of Korean Institute of Industrial Engineers
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• v.17 no.1
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• pp.51-58
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• 1991

This paper presents a single-echelon, single item, stochastic lead time and static demand inventory model for situations in which, during the stockout period, a fraction ${\beta}$ of the demand is backordered and the remaining fraction $(1-{\beta})$ is lost. In this situations, an objective function representing the average annual cost of inventory system is obtained by defining a time-proportional backorder cost and a fixed penalty cost per unit lost. The optimal operating policy variables minimizing the average annual cost are calculated iteratively. At the extremet ${\beta}=1$, the model presented reduces to the usual backorder case. A numerical example is solved to illustrate the algorithm developed.