• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.333-334
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• 2006

A novel mathematical modeling in web transport systems for Continuous Annealing Processes (CAP) is proposed. Despite of thermal and weight effects in dynamics of web transport systems, the conventional mathematical model does not consider those effects. Disregard of these effects causes the low manufacturing quality of webs in CAP. In order to improve the manufacturing quality of webs in CAP, moreover, precise tension control is required based on the mathematical model. Therefore, an advanced mathematical model considering thermal and weight effects in CAP should be established. The effectiveness of a novel mathematical model is evaluated by comparing the performances of the PI tension control system based on the proposed mathematical model with that based on the conventional one through the computer simulation.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.2
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• pp.43-54
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• 2014

Environmental pollution including air, land, and water has become one of the most critical issues in global interest. The damages due to environmental pollution lead to serious disasters. Nations have realized the importance of environment protection and have been starting to force organizations to implement environmental management system (EMS) as way of protecting environment. ISO 14001 requirements that are the most popular standard as EMS have been developed to support continuous improvement to environment management. It has been revised once since publication and ISO 14001 : 2004 version is currently available. Organizations globally started to acquire the certificate of EMS to observe environment related laws, accept customers' and stakeholders' request, increase market share, and fulfill implementation motives. This article examines the audit data that were collected for several years from manufacturing companies including shipbuilding, machinery, metal, automobiles, and chemical companies in southeastern Korea on the basis of ISO 14001 : 2004 requirements. The audit data were classified into minor nonconformities based on factors such as business size, business type, and EMS implementation period. We conduct hypotheses test using statistical methods in order to see if there are any significant differences based on the factors. We draw conclusions for the results of hypotheses test and address the necessities of energy, greenhouse gas, green management, and continuous improvement to enhance the efficiency of EMS implementation.

• Journal of Mechanical Science and Technology
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• v.14 no.4
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• pp.380-392
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• 2000

A typical production-distribution system consist of three main echelons representing the retailer, distributors, and a factory each with an on-site warehouse. The system is sufficiently general and realistic to represent many industrial situations. However, decision functions and parameters have been selected to apply particularly to the production and distribution of consumer durables. The flows included in the model are materials, orders, and those information flows needed to support the material and order-rate decisions. In this work, a realistic production-distribution system has been used as a basic model, which consists of three sectors: retailer, distributor, and factory. That system is a nonlinear 25th-order continuous system interconnected between the echelons. Using a modern control algorithm, a typical multi-echelon production-distribution system using a dynamic controller is numerically simulated in the nominal plant and in the perturbed plant when the piecewise constant manufacturing decision is limited by a factory manufacturing upper-limit due to capital equipment, manpower, and factory lotsize.

• Journal of the Korean Society for Heat Treatment
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• v.25 no.6
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• pp.292-298
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• 2012

In this study, Cu-2.5at.%Ni-1at.%Si alloys were fabricated by horizontal continuous casting system to improve the electrical conductivity and mechanical properties of Cu-Ni-Si alloy. Withdrawing speed was changed with 50, 100, 150 and 200 mm/min for the optimum manufacturing condition. Microstructure was observed using OM, FE-SEM and TEM. Electrical conductivity was measured by 4-point probe method and mechanical properties were tested. A horizontal continuous cast thin slab had sound macro and micro structures with partly crystallized structures. Electrical resistivity decreased with increasing annealing temperature from 250 to $850^{\circ}C$, with increasing annealing temperature The maximum hardness and tensile strength were Hv 130, 610 MPa at $550^{\circ}C$, respectively. With changing withdrawing speed from 50 to 150 mm/min, hardness, tensile strength, yield strength and elongation were Hv 60-65, 210-230 MPa, 65-75 MPa and 40-50%, respectively.

• Journal of the Korea Safety Management & Science
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• v.24 no.3
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• pp.93-103
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• 2022

This study investigated the method of continuous improvement of small-medium company production processes through POSCO's QSS(Quick Six Sigma) activities. QSS is a field operation technique that encompasses the advantages of Six Sigma, TPS(Toyota Production System), TQM (Total Quality Management), and IE(Industrial Engineering). Through this, POSCO not only encourages activities centered on related small and medium-sized partners, etc., but is also expected to contribute to the continuous improvement of the company's own production process through QSS activities. In this study, rather than unconditionally carrying out activities according to the needs of large companies, the research is to help the continuous improvement of the actual production process of small and medium-sized enterprises by effectively applying and spreading QSS activities in consideration of the characteristics and environment of the company. For this purpose, empirical research is conducted on the process improvement activities and QSS activities of company Y, which has less than 100 assembly and production quality and inspection processes among SMEs. The changes in the production process improvement of SMEs through the application of the final QSS were investigated through empirical studies.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.3 s.147
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• pp.392-398
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• 2006

A prototype of MES(Manufacturing Execution System) applied to panel assembly shop is implemented by using PDA(Personal Digital Assistant) and wireless database web server. The system is developed based on the Dot Net framework. The prototype can exchange the manufacturing execution data between production managers in the control room and workers in the factory through wireless internet communication. Manufacturing model of the panel shop is designed by using IDEF0 and UML method to understand the characteristics of the information and the data entities from the PPR-S view. Several issues in the shop were revealed from the manufacturing model analysis. The most typical problem was the lack of information sharing between the managing workers and the assembly workers. The problem prevents the workers and labors from sharing the process information and continuous workpiece flow In interactive way. To increase the information and data flow, a wireless internet based system is implemented and PDAs are linked together to exchange the process planning data and in-process data between the workers. It is anticipated that PDA and the implemented system can enable the process control at each process stages to obtain the well-organized operation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.653-658
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• 2011

In general, the purpose of packaging fasteners is a series of management activities to maintain the condition at the time of production until they get delivered to the end user. An automatic packing system for fasteners is consisted of bucket conveyor, slide feeder, vision inspection system, box-magazine conveyor system and automatic packing machine. Also, the automatic packing machine is consisted of six modules including charging device, clamping/opening device, sealing/cutting device, feeding/air-shower device, supplying/adjusting device and device frame, etc. In this paper, we proposed an automatic packing mechanism of the one station concept for packing work of fastener objects where the continuous batch work is performed in a finite space. The proposed one-station packing mechanism has been optimized through mechanical, dynamical, structural and fluid analyses. And it had been manufactured as the prototype of automatic packing machine. The field test for validation of performance was performed directly at the production line of bolt and screw. In the field test, this packing machine showed an efficiency of about 4.5 times the manual operation. It also showed 30% reduction in the consumption of packing materials compared to the manual operation. This automatic packing machine for fastener objects will be commercialized soon.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.2
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• pp.88-93
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• 2017

Due to the requirement of the development of the precision manufacturing industry, the accuracy of machine tools has become a key issue in this field. A critical factor that affects the accuracy of machine tools is the feed system, which is generally driven by a ball screw. Basically, to improve the performance of the feed drive system, which will be thermally extended lengthwise by continuous usage, a thermal error compensation system that is highly dependent on the feedback temperature or positioning data is employed in the machine tool system. Due to the overdependence on measuring technology, the cost of the compensation system and low productivity level are inevitable problems in the machine tool industry. This paper presents a novel feed drive thermal error compensation system method that could compensate for thermal error without positioning or temperature feedback. Regarding this thermal error compensation system, the heat generation of components, principal of compensation, thermal model, mathematic model, and calculation method are discussed. As a result, the test data confirm the correctness of the developed feed drive thermal error compensation system very well.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.11
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• pp.2313-2320
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• 2011

The management of a panel block shop in a shipyard is a complex process that entails the largest amount of work and in which many decisions are involved. Shipbuilders have considered the process as a bottleneck since every panel for every ship and offshore hull structure must be processed through the shop. In order to maximize process productivity, simulation-based ship production execution system(SPEXS) is proposed for panel block operations utilising discrete-event simulation and simulated annealing. An application of panel block assembly shop, called SPEX-Panel supports production planners by general dispatching rules and metaheuristics to make better scheduling decisions on the shop floor. In addition, the system will help increase productivity in the yard with continuous improvement.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.625-631
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• 2002

In the previous study, a polishing robot system was developed to automate the polishing process and to cope with the shortage of skilled workers. This polishing robot system has several advantages: reduced time for setting polishing work, decreased labor costs, effective operation, continuous polishing work without an operator, improved machine accuracy, and the ability to polish a free curved surface die. However, still the problem remains that a worker must stay to monitor the polishing process in the poor working conditions for a long time. Nowadays some advanced manufacturing companies need to find a way to check the performance of their production equipments and plants from remote sites. Thus, this study constructed the communication network and developed the monitoring programs (a servo program and a client program) to operate the polishing robot from remote sites. Using these programs, workers are able to monitor and control the polishing robot on the web page, in any place where internet service is possible. To guarantee a stable operation in spite of a variable computer operating environment, the monitoring system is implemented in Java. The experimental results showed that the developed monitoring programs provided a stable communication.