• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.1
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• pp.116-122
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• 2016

Recently, the production cycle in manufacturing process has been getting shorter and different types of product have been produced in the same process line. In this case, the control chart using coefficient of variation would be applicable to the process. The theory that random variables are located in the three times distance of the deviation from mean value is applicable to the control chart that monitor the process in the manufacturing line, when the data of process are changed by the type of normal distribution. It is possible to apply to the control chart of coefficient of variation too. ${\bar{x}}$, s estimates that taken in the coefficient of variation have just used all of the data, but the upper control limit, center line and lower control limit have been settled by the effect of abnormal values, so this control chart could be in trouble of detection ability of the assignable value. The purpose of this study was to present the robust control chart than coefficient of variation control chart in the normal process. To perform this research, the location parameter, ${\bar{x_{\alpha}}}$, $s_{\alpha}$ were used. The robust control chart was named Tim-CV control chart. The result of simulation were summarized as follows; First, P values, the probability to get away from control limit, in Trim-CV control chart were larger than CV control chart in the normal process. Second, ARL values, average run length, in Trim-CV control chart were smaller than CV control chart in the normal process. Particularly, the difference of performance of two control charts was so sure when the change of the process was getting to bigger. Therefore, the Trim-CV control chart proposed in this paper would be more efficient tool than CV control chart in small quantity batch production.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.733-743
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• 1989

This paper deals with the control of system with controlled jump Markov disturbances. A such formulation was used by Boukas to model the planning production and maintenance of a FMS with failure machines. The optimal control problem of systems with controlled jump Markov process is addressed. This problem describes the planning production and preventive maintenance of production systems. The optimality conditions in both cases finite and infinite horizon, are derived. A numerical example is presented to validate the proposed results.

• Fashion & Textile Research Journal
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• v.14 no.4
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• pp.597-606
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• 2012

To increase the productivity and product quality of customized baseball jerseys, this study developed a multi-variable system for a production process that efficiently controls diverse production management factors. The working time was measured through the establishment of a standard process where skilled workers and Chinese factory workers manufactured 5 sets of the same basic design jerseys. Based on the measured working time (1,136 seconds/per unit), the multi-variable process control system was developed, where hourly production management is possible according to the involved workers and equipment types. Each process was assigned accoding to the production management factors for a total of 28 standard processes. The processes were developed based on consideration of work characteristics according to the order of needlework of open-type set baseball jerseys with sleeves(the basic design of baseball jerseys)to result in a customized production system structure that could be set up with multi-variables. As a result, a total 12 types of systems were developed in consideration of the personnel involved and the number of equipments. The optimal production management system (with the highest efficiency compared to the number of workers)was A-2, B-1, C-1. D-2, E-2, F-1, and G-1. This system had extremely high efficiency and showed 99% assignment efficiency for the 7-person team. Though not optimal, possible process assignment for each working personnel is proposed as a reserve process in case work modification is inevitable due to malfunctions and the absence of equipments.

• Transactions on Control, Automation and Systems Engineering
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• v.3 no.1
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• pp.1-9
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• 2001

The promise of improved productivity and quality has lead to numerous research investigations in machining process monitoring and control. Recent studies have demonstrated that careful attention must be paid to the regulation of multiple process modules within a single operation such that each module performs its function properly and adverse interactions between modules do not occur. This had lead to the development of supervisory control; particularly to the development of methodologies to systemati-cally construct and implement these controllers. However, no research study has investigated the effect of the production environ-ment on the design of supervisor controllers. In this paper, the design of supervisory controllers for various production environ-ment is studied. The design approach given in Landers and Ulsoy(1998) is applied to construct two supervisory machining control-lers that are experimentally implemented in a face milling operation. Comparisons with an experimental implementation without process control illustrate the benefits of utilizing process controllers that are coordinated properly. The results also show that the given design approach may be used to construct supervisory controllers for different types of production environments.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.8
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• pp.419-424
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• 2020

This study analyzes the new GMCF method applied by the company with the aim to find out how the production of Accounting Information Systems (AIS) implemented by the company can be managed properly. The study also seeks to find out whether the company needs new system support facilities to facilitate the production performance reporting process of each division and evaluate the performance of GMCF systems in the company. The methods used are descriptive analysis techniques and statistical tests of Paired Sample T-Test comparison; this study uses production data of each unit of a product with random sampling to determine the level of product damage and compare production with the GMCF system and prior to using it. The results of the analysis found that the application of goods mutation control forms (GMCF) greatly influenced the smooth production reporting process, which resulted in an increase in achieving production targets and reducing the risk of product damage during the production process. The company also benefits from the efficiency of production costs when using the GMCF system and can quickly design policies for products that are damaged during the production process. In addition, the company can have damaged products repaired faster than before.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1215-1220
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• 2004

Reactive distillation (RD) is a combination process where both separation and reaction are considered simultaneously in a single vessel. This kind of combination to enhance the overall performance is not a new attempt in the chemical engineering areas. The recovery of ammonia in the classic Solvay process for soda ash of the 1860s may be cited as probably the first commercial application of RD. The RD system has been used for a long time as a useful process and recently the importance of the RD is enlarged more and more. In addition to that, the application fields of RD are diversely diverged. To make the most of the characteristic of RD system, we must decide the best operating condition under which the process shows the most effective productivity and should decide the best control algorithm which satisfies an optimal operating condition. Phosgene which is a highly reactive chemical is used for the production of isocyanates and polycarbonates. Because it has high reactivity and toxicity, its utilization is increasingly burdened by growing safety measures to be adopted during its production. Dimethyl Carbonate (DMC) was proposed as a substitute of phosgene because it is non-toxic and environmentally benign chemical. In this study, RD is used for DMC production process and the transesterification is performed inside of column to produce DMC. In transesterification, the methanol and ethylene carbonate (EC) are used as the reactants. This process use homogeneous catalyst and the azeotrope exists between the reactant and product. Owing to azeotrope, we should use two distillation columns. For this DMC production process, we can suggest two configurations. One is EC excess process and the other is methanol excess process. From the comparison of steady state simulation results where the Naphtali-Sandholm algorithm is used, it showed the better performance to use the methanol excess process configuration than EC excess process. Then, the dynamic simulation was performed to be based on the steady state simulation results and the optimal control system was designed. In addition to that, the optimal operating condition was suggested from previous results.

• Journal of the Korea Safety Management & Science
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• v.5 no.4
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• pp.169-185
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• 2003

Recently many researchers contributed to the understanding of Quality Control System, but the use of economics in the design of quality assurance system is limited in treatment of the relationship between the average incoming quality level (or average process quality level) of the incoming lot and the average outgoing quality level of this lot. In this study, a traditional concept of sampling inspection plan for the quality assurance system is extended to a consideration of economic aspects in total production system by representing and analyzing the effects between proceeding and succeeding production process including inspection process. This approach recognizes that the decision at each manufacturing process (or assembly process), is to be determined not only by the cost and the average outgoing quality level of that process, but also by the input parameters of the cost and the incoming quality to the succeeding process. By analyzing the effects of the average incoming and outgoing quality, manufacturing or assembly process quality level and sampling inspection plan on the production system, mathematical models and solution technique to minimize the total production cost for a general product manufacturing system with specified average outgoing quality limit are suggested.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.42
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• pp.73-85
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• 1997

In the product liability age the demand on quality is extremely high and inspection and test are automated. The process capability indices $C_p, {\;}C_{pk}$ and p control chart widely used to provide unitless measure of process performance and process control. Traditional process capability indices $C_p, {\;}C_{pk}$ do not represent the process variation from target value. The convention p chart for control of fraction nonconforming becomes inadequate when the fraction nonconforming becomes very small such as PPM level production system. This paper proposes process performance measure considering quadratic loss function and cumulative counts control chart for control of PPM level production system.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.2
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• pp.233-239
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• 2014

This paper presents an extended EMQ model which determines an optimal production run length in an deteriorating production process. The production process is subject to a random deterioration from an in-control state to an out-of-control state and thus producing some proportion of defective items. Defective items produced are re-processed in the rework process to convert them into non-defectives. Through the mathematical modeling, an optimal solution minimizing the average cost per unit time as well as minimum average cost are derived. Numerical experiment is carried out to examine the behavior of the proposed model depending on model parameters.

• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.150-152
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• 2004

The battery charge/discharge process, the final step of the secondary battery production process, requires real-time precision controls for improving both lifetime and performance of the battery cell. In this paper, we present embedded system design for precision control of the secondary battery charge/discharge production process using low power embedded processor based on embedded linux. This system receive charge/discharge command from the main server through ethernet. Compared to existing charge/discharge control system, our design makes low cost and precision control system possible.