• Journal of applied mathematics & informatics
• /
• v.11 no.1_2
• /
• pp.291-304
• /
• 2003

Inventory of differential (both good And defective) items purchased in a lot for two shops under a single management is considered here. In the primary shop, the lot is received and separated, only good units are sold and shortages are allowed which are backlogged from the good units specially purchased at the beginning of the next cycle. The separated defective units are continuously transferred and sold at a reduced price from the secondary shop. This inventory model is formulated and illustrated numerically for three scenarios depending upon the time periods of the shops. Inventory, deterioration, two shops.

• Journal of Korean Society for Quality Management
• /
• v.24 no.2
• /
• pp.44-53
• /
• 1996

This paper deals with the problem of selecting optimal wear limit and initial process mean in a wear-out process. Consider a material removal processing machinery where 1)there are deffective items by linear shift in the mean of the diameter of to be processed with varing process variance and 2)there can be any failure in the machine tools or to be processed. In the previous studies, the one is analyzed by 'Model of Producing Goods' in quality control area and the other, any failure, is analyzed by 'Model of Producing Services' in reliability area. We propose a new integrated maintenance model, considering the percent defective and the failure rate. A numerical example for the model is given.

• IE interfaces
• /
• v.21 no.2
• /
• pp.221-228
• /
• 2008

The injection molding process is able to produce high precision manufactures as a single process with fast speed. However, the prices of both the mold and the molding machine are expensive, and the single process is very complex and difficult to compose of the exact relationship between the process setting conditions and the product quality. Therefore, the quality of a molded product often depends on a skillful engineer's operations in the design of both parts and molds. In this paper, the relationship between the process conditions and the defectiveness is built for better manufactures under settings of the appropriate parameters, and so it can reduce the setup time in the injection molding process. Quality Function Deployment (QFD) provides severe defectiveness factors along with the related process parameters. Also, neural networks estimate the relationship between defective factors and process setting parameters, and lead to reduce the defectiveness of molded parts.

• Journal of IKEEE
• /
• v.27 no.3
• /
• pp.345-349
• /
• 2023

In this paper, we propose a study on the development of deep learning structure for defective pixel detection of next-generation smart LED display board using imaging device. In this research, a technique utilizing imaging devices and deep learning is introduced to automatically detect defects in outdoor LED billboards. Through this approach, the effective management of LED billboards and the resolution of various errors and issues are aimed. The research process consists of three stages. Firstly, the planarized image data of the billboard is processed through calibration to completely remove the background and undergo necessary preprocessing to generate a training dataset. Secondly, the generated dataset is employed to train an object recognition network. This network is composed of a Backbone and a Head. The Backbone employs CSP-Darknet to extract feature maps, while the Head utilizes extracted feature maps as the basis for object detection. Throughout this process, the network is adjusted to align the Confidence score and Intersection over Union (IoU) error, sustaining continuous learning. In the third stage, the created model is employed to automatically detect defective pixels on actual outdoor LED billboards. The proposed method, applied in this paper, yielded results from accredited measurement experiments that achieved 100% detection of defective pixels on real LED billboards. This confirms the improved efficiency in managing and maintaining LED billboards. Such research findings are anticipated to bring about a revolutionary advancement in the management of LED billboards.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2007.11a
• /
• pp.718-721
• /
• 2007

Construction schedule plays a key role in project management due to its influence on the project success. Thus, it is important to identify factors affecting construction delay. The major objective of this study is to identify and evaluate factors affecting construction delay in apartment projects in Vietnam. The findings confirmed that financial difficulties of owners and contractors, contractors without adequate experience, non-available materials on time, slow site clearance, inappropriate construction methods, defective works and reworks, and lack of capable owners/project managers are the major causes of delay in apartment projects.

• Journal of Korean Society for Quality Management
• /
• v.27 no.1
• /
• pp.211-222
• /
• 1999

6 Sigma is defined as the state of "defect free quality" with only 3.4 defective, goods out of 1 million. Samsung Display Device(SDD) was quick to embark on a new way of quality innovation. The goals of 6 Sigma campaign are established on the foundation of customer satisfaction such as quality, cost and service. Production field of SDD has a special 6 Sigma campaign, SQM(Standard Quality Management). Quality qualification system is introduced and implemented with strong reinforcement. C-S-I(Chart-Solve-Implement) model which was made by Dr. Bajaria(1991) is adopted for the project. All the workers of company will be encouraged to participate in the drive.

• Journal of the Korea Safety Management & Science
• /
• v.16 no.1
• /
• pp.169-176
• /
• 2014

This research discusses the characteristics and the implementation strategies for two types of quality metrics to analyze innovation effects in six sigma projects: fixed specification type and moving specification type. $Z_{st}$, $P_{pk}$ are quality metrics of fixed specification type that are influenced by predetermined specification. In contrast, the quality metrics of moving specification type such as Strictly Standardized Mean Difference(SSMD), Z-Score, F-Statistic and t-Statistic are independent from predetermined specification. $Z_{st}$ sigma level obtains defective rates of Parts Per Million(PPM) and Defects Per Million Opportunities(DPMO). However, the defective rates between different industrial sectors are incomparable due to their own technological inherence. In order to explore relative method to compare defective rates between different industrial sectors, the ratio of specification and natural tolerance called, $P_{pk}$, is used. The drawback of this $P_{pk}$ metric is that it is highly dependent on the specification. The metrics of F-Statistic and t-Statistic identify innovation effect by comparing before-and-after of accuracy and precision. These statistics are not affected by specification, but affected by type of statistical distribution models and sample size. Hence, statistical significance determined by above two statistics cannot give a same conclusion as practical significance. In conclusion, SSMD and Z-Score are the best quality metrics that are uninfluenced by fixed specification, theoretical distribution model and arbitrary sample size. Those metrics also identify the innovation effects for before-and-after of accuracy and precision. It is beneficial to use SSMD and Z-Score methods along with popular methods of $Z_{st}$ sigma level and $P_{pk}$ that are commonly employed in six sigma projects. The case studies from national six sigma contest from 2011 to 2012 are proposed and analyzed to provide the guidelines for the usage of quality metrics for quality practitioners.

• Journal of Korean Society for Quality Management
• /
• v.31 no.3
• /
• pp.19-36
• /
• 2003

The manager of manufacturing industry just not to have known what to do related to the law of product liability(PL) that was put into operation in July 1, 2002. The law of PL is a public law about defective product, which was established in order to compensate consumer's damages of property and body caused by product, to make sound society by the safety products and to take international competitiveness. But the existing civil law has been having clause that compensation to be taken is limited. The law of PL is resolving this limitations and is characterized by the easy relief from damages of defective product. The decision in the case of Green-man has been a precedent since the court sentenced the manufacturer to liability. The law of PL has been in force in 27 countries, including all of the EU countries, Japan, Philippines and China. It has been shown that the corporations which meet the Global Standard, could survive in global competition. The economic effects by the law of PL are the increase of consumers relief production cost by the lawsuits. This paper will recommend more biref method that is able to cover PSMS by use of QMS. It will make domestic corporation improve in the plan, manufacture and sale of products to meet the Global Standard.

• Journal of Korean Society for Quality Management
• /
• v.12 no.2
• /
• pp.33-36
• /
• 1984

This paper is concerned with the optimal replacement policy of auto-scale with increasing error-variance. This optimization model is to minimize the sum of the cost of defective and excess weight allowance for a target value. The numerical example for the proposed problem is solved by Golden-Section Search and Simpsons's rule.

• Journal of Korean Society for Quality Management
• /
• v.16 no.2
• /
• pp.92-98
• /
• 1988

In this paper a model is developed for an inventory system in which the number of units of acceptable quality in a replenishment lot is uncertain and the demand. during the stockout period is back ordered and. also under the same condition an inventory model with experdited stockout is developed. It is assumed that the fraction of the acceptable quality in a replenishment lot is a random variable whose probability distribution is known. The optimal replenishment policy is synthesized for such a system. A numerical example is used to illustrate the theory.