• Journal of Korean Society for Quality Management
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• v.34 no.1
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• pp.1-12
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• 2006

This paper presents a six sigma project for improving gate painting quality in a medium-sized automotive part company. The project follows a disciplined process of five macro phases: Define, Measure, Analyze, Improve, and Control. A CTQ(critical to quality) is determined based on COPQ(cost of poor quality) analysis, and a process map is utilized for identifying process input variables. Three KPIV s(key process input variable) are selected; Painting Temperature, Painting Quantity, and Painting Viscosity, and DOE(design of experiments) is utilized for finding the optimal process conditions for three KPIVs. MINITAB software is used for data analyses and DOE. The sigma level of defects rate has improved from 2.93 to 3.66.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.4
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• pp.48-54
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• 2005

Recently, a couple of process capability indices are used to evaluate that the outputs of the process satisfy the specifications. An assumption of those indices is that the specifications of the characteristics are given single constant value. The display panel is a highly precise product and all the specifications of measure points are designed by their locations in the panel. So it is very difficult to locate the measurement facility to the exact position. In this paper, we propose a new process capability index in case of multi specifications and unfixable objects.

• Journal of the Korea Safety Management & Science
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• v.13 no.4
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• pp.153-160
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• 2011

This thesis introduced a model of diagnosing a company's quality management, and a process of achieving quality innovation based on the model. As for study methods, books and theses related to quality and process innovation were collected for investigation, a survey on internal employees to investigate major issues of quality and standard consciousness was conducted, and 5DP was discussed for balanced process analysis.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.4
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• pp.183-193
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• 2019

Process mining is an analytical technique aimed at obtaining useful information about a process by extracting a process model from events log. However, most existing process models are deterministic because they do not include stochastic elements such as the occurrence probabilities or execution times of activities. Therefore, available information is limited, resulting in the limitations on analyzing and understanding the process. Furthermore, it is also important to develop an efficient methodology to discover the process model. Although genetic process mining algorithm is one of the methods that can handle data with noises, it has a limitation of large computation time when it is applied to data with large capacity. To resolve these issues, in this paper, we define a stochastic process tree and propose a tabu search-genetic process mining (TS-GPM) algorithm for a stochastic process tree. Specifically, we define a two-dimensional array as a chromosome to represent a stochastic process tree, fitness function, a procedure for generating stochastic process tree and a model trace as a string of activities generated from the process tree. Furthermore, by storing and comparing model traces with low fitness values in the tabu list, we can prevent duplicated searches for process trees with low fitness value being performed. In order to verify the performance of the proposed algorithm, we performed a numerical experiment by using two kinds of event log data used in the previous research. The results showed that the suggested TS-GPM algorithm outperformed the GPM algorithm in terms of fitness and computation time.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1112-1114
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• 2009

In this paper, we have studied manufacturing process for liquid crystal displays (LCDs) using plastic substrates. Because the thermal and dimensional stabilities of plastic substrates are decisive issues, both the process and materials were improved to fit the manufacturing requirements of flexible twisted-nematic (TN) and color super-twisted nematic (CSTN) LCDs. Finally, to broaden the flexible display applications, we take advantage of the unique properties of flexible display to design several innovative products.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.6023-6028
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• 2013

Recently, biodegradable polymers are gaining more and more attention due to international environmental issues. Succinic acid is synthesised by chemical process of hydrogenation. Succinic acid synthesized has certain amount water content. To remove the water contained in succinic acid is used generally by hot air drying process. But recently, microwave drying process having the advantage of shortening the drying time and uniform drying of product are gaining more attention. In this study, hot air drying and microwave drying efficiency were compared at drying process. In addition, we confirmed commercial applicability in microwave drying process of succinic acid. Microwave drying process has higher efficiency than 70% compared with hot air drying process at thickness of 1cm. Economic efficiency were compared through examination of power consumption for complete drying of succinic acid at microwave and hot air dyring.

• 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.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.4
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• pp.41-47
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• 2012

To adapt to a rapidly changing business environment, introduction of new management techniques and innovative activities are crucial. In the case of small and medium companies, the compensation for scarce management resources and sustainable development can be obtained from advantage of management consulting. In this study, we propose the enterprise process evaluation model for small and medium business consulting, which can deploy the process improvement activities with considering the process maturity level within an organization. The process evaluation area of proposed Small and Medium Business, Staged Maturity Model (SMB-SMM) consists of four following parts: supply management, demand management, business management, and research and development (R&D) management. For each area, we set goals and also define the practices to achieve their goals respectively. By applying the SMB-SMM model to the small and medium sized companies, the process maturity level can be defined. And then to overcome the gap between the goals and evaluation results, the customized management consulting activities can be drawn from the predefined consulting approaches from the SMB-SMM.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.6
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• pp.445-462
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• 2020

Industrial wastewater often contains a number of recalcitrant organic contaminants. These contaminants are hardly degradable by biological wastewater treatment processes, which requires a more powerful treatment method based on chemical oxidation. Advanced oxidation technology (AOT) has been extensively studied for the treatment of nonbiodegradable organics in water and wastewater. Among different AOTs developed up to date, ozonation and the Fenton process are the representative technologies that widely used in the field. Based on the traditional ozonation and the Fenton process, several modified processes have been also developed to accelerate the production of reactive radicals. This article reviews the chemistry of ozonation and the Fenton process as well as the cases of application of these two AOTs to industrial wastewater treatment. In addition, research needs to improve the cost efficiency of ozonation and the Fenton process were discussed.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.175-176
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• 2008

향후 개발되어질 Digital Power IED (Protection & Measuring, Control, Supervision etc.) 에서 제작된 H/W 및 Simulation용 Target Board 의 Firmware Process Flow 지침으로서 개발 경험을 바탕으로 보다 안정적이고 효율적인 Programming 을 가능하게 하고, 실시간 연산 Process 의 기준 확립 및 이해를 통한, 개선 아이디어 도출 및 수정 필요시 빠른 Trouble-Shooting 능력을 배양할 수 있다. 새로운 Process 아이디어의 Simulation 적용 및 확인으로 호환성과 안정성에 기반하는 F/W Optimization을 항상 유지 관리할 수 있으며, Measuring Element (전압, 전류, 전력, 주파수 등), Protection Element (OC, OCG, OV, OVG, UV, UC, DOC 등) 의 기준을 정함으로서 새로운 개발자에게는 개발 실무를 위한 교육 자료로 이용하고, 기존 개발자들에게는 안정된 F/W 모듈을 제공한다. 본 논문에서는 개발 시간을 단축하고, 다양한 진보 Process 접근을 원활히 할 수 있는 F/W 및 S/W 시뮬레이터를 제시한다.