• Journal of the Korean Society for Precision Engineering
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• v.22 no.4
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• pp.27-36
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• 2005

Some studies have shown that unstable factors are inherent in WEDM process, causing the instability of the discharging pulse to reach about 40∼60％ in normal machining. Transient stability is an important subject in WEDM process since there is a close relationship between stability and machining performance, such as the characteristics of a machined surface, machining speed and problem of instability like wire rupture phenomenon. Among the many machining parameters affecting WEDM machining state, three specific parameters (Vr, Ip, off time ) are major controllable variables that can be applied in transient stability control. And, this research investigates the implementation and analysis of real-time micro control of the discharging stability of WEDM (Wire Electric Discharge Machining) process.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.132-137
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• 1993

In this paper, a fish drying process control system is proposed, which predicts the proper change with time in weight of the material fish and the drying conditions in advance, based on the performance of skilled worker. In order to implement a human expertise into an automated fish drying process control system, an experimental analysis is made and a model for the process is built. The proposed system divided into two procedures: The procedure before drying and the one during drying. The procedure before drying is for the prediction of necessary drying time. To estimate the necessary drying time, first, the proper change in weight for the product is obtained by using fuzzy reasoning. The condition part of the production rule consists of the factors of fish body and the expected degree of dryness. Kext, the necessary drying time is obtained by regression models. The variables employed in the models are the factors, inferred change in weight and drying conditions. The model for the procedure during drying is also proposed for more accurate estimation, which is described by a system of linear-differential equations.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.2
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• pp.18-24
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• 2009

The most dominate aspect in machine works using CNC devices in industrial production processes is the precision of the product and the Cycle Time. To this day, many studies on the external factors of the technology to reduce the Cycle Time have advanced amid to the advancements in cam soft development for manual programs and the numerous studies on high speed and precision machining. This study experimented various functions of the sequence pattern flow and arranged system development technologies of past few years to develop and applicate various usage of adjustment factors within the CNC, so it would be more understandable to the user and would enable them to make high speed and precision products more faster develop and. In order to reduce the Cycle Time, the mechanism of machine tools has to be analysed and applied, in addition to program reduction and improvement of the manufacture process.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.447-450
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• 2006

Hydrogen separation from multi-component mixture gases by the four-bed PSA process was studied experimentally and theoretically using layered bed of activated carbon and zeolited 5A. Effects of the adsorption time, the linear velocity on the process performance were investigated. The adsorption time and linear velocity affected the purity and recovery of the product $H_2$ purity is increases according as the adsorption time and linear velocity decrease; however, $H_2$ recovery shows an opposite phenomena to the purity. PSA process simulation studied to find optimum operation condition. In the results, 50sec adsorption time, 3cm/s linear velocity might be optimal values to obtain more than 99.999% purity and 65% recovery hydrogen.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.151.3-151
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• 2001

A design of PI controller to be used to control the first-order lag plus dead time process, such as a flow process, by the coefficient diagram method (CDM) is investigated. The factor of the dead time of process is first approximated to be the first-order by the Pade approximation. The response of the flow control system designed by CDM satisfy both transient and steady state specifications. However, the transient response generally still has long rise time. In order to improve the speed of the system response, a feedforward controller (FFC) is added into the PI control system. The structure of the FFC is a phase lead structure with two designed parameters and one derivative time obtained from the reaction curve of the flow process ...

• Transactions of Materials Processing
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• v.18 no.8
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• pp.616-624
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• 2009

In this work we demonstrate the hot-embossing process under different forming conditions such as forming temperature, load, and holding time in pressing, in order to determine the suitable conditions required for linear patterning on polymer plates (PC). Results showed that the replicated pattern depth increased in proportion to an increase in the forming temperature, load, and time. The reduction of the workpiece thickness increased according to the holding time in the pressing process. In the process of time, the reduction ratio of the workpiece thickness decreased due to the surface area increment of the workpiece, while the pressure on the workpiece declined. In order to reduce the bulging ratio we introduced a temperature difference between the upper and the lower punch.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.7 s.238
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• pp.1022-1027
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• 2005

In this study, ball milling process was applied to reduce the particle size of bio-material down to submicron size. The material used was Ibuprofen. The ball milling was performed at low temperature of about $-180^{\circ}C$. The effect of processing conditions (milling time, milling speed) on the particle size was determined. The results showed that the degree of crystallite of Ibuprofen was slightly reduced by the ball milling process. The results also showed that the size of Ibuprofen was significantly reduced by the ball milling process. The effect of milling time was significant within the milling time of six hours while it was small thereafter.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.3
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• pp.95-102
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• 2012

It is not easy to establish the correct standard time and standard manhour in a process of small quantity batch production system, especially in a case of irregular quantity of production. Therefore, how to establish rational standard time about manufacturing process of a power cable company which is representative business for small quantity batch production system will be suggested in this paper. Furthermore, how to establish standard manhour which can be used for effective control of labor productivity will also be presented.

• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.4
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• pp.63-70
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• 2019

The subject of the simultaneous measuring system of base pattern and deposition pattern is a new research topic on a defect inspection of OLED. In this paper, we propose a new OLED inspection method that simultaneously measures standard and deposition pattern images. This method reduces unnecessary processes and tac time during OLED inspection. For an additional reduction of the tac time during pattern measurement, the ROI was configured to measure only in the designated ROI area instead of measuring the entire area of an image. During the ROI set-up, the value of effective deposition pattern area is included so that if the deposition pattern is out of the ROI zone, it would be treated as a defect before measuring the size and center point of the pattern. As a result, the tac time and inspection process could be shortened. The proposed method also could be applied to the OLED manufacturing process. Production of OLED could be increased by reducing tac time and inspection process.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.28-30
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• 2009

PDP panels with MgO protective layer are manufactured by using the "all-in-vacuum" process we have established [1]. This is the process aiming to keep the MgO surface as clean as possible after the evaporation. The panels are evaluated in term of discharge voltage, aging time, luminance, luminous efficacy, discharge time-lag. It is confirmed that the "all-in-vacuum" process particularly improves the aging time, discharge voltage and the discharge time-lag.