• Korean Journal of Computational Design and Engineering
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• v.16 no.3
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• pp.187-196
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• 2011

Generally, BOM (Bill of Material) means a part list which is needed to manufacture or assemble a product or part. During manufacturing processes, BOM is inevitably required for most of enterprise processes such as design, procurement, production planning/control, resource planning, and financial works. Every manufacturing industry uses many kinds of BOM's that are adjusted to the requirement of functions of their work division. Moreover, BOM evolves in different forms according to the product development phases such as conceptual design; function design, detail design, and production design because it is necessary to use different product structures to keep product data generated throughout the lifecycle of a product. This includes all data and information related to the all the product development phases. Shipbuilding works also are processed and controlled based on BOM. However, effective maintenance of ship outfitting BOM data is getting difficult as the amount and complexity of data have increased due to variety and long lifecycle of ship. For the effective management of outfitting BOM data, two aspects must be considered. One is how to classify numerous BOMs type and the others how to display BOMs. So this study suggests a method to classify BOM types and propose two categories - Structure BOM, Display BOM. Base on this result, we propose the integrated ship outfitting BOMs model and analysis outfitting BOMs.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1697-1699
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• 2001

In this paper, the circuit of AC Choppers for $CO_2$ laser power supply are proposed and investigated. IGBT-controlled ac voltage regulators, operating at high frequency chopping mode. Chopping-to-supply duty ratio plays an important role in terms of laser output. Laser input energy is varied by controlling the leakage transformer used with the proposed system. This improved circuit employs a 3 electrode - type and Ring Blower. This improved circuit system has many advantages compared with the conventional SMPS such as simple design requirement, easy implementation, high reliability, low switching loss, and consequently high efficiency. As a result, the maximun output was 16W at duty-ratio of 92%, total gas mixture of $CO_2$ : $N_2$ : He = 1 : 9 : 15, total pressure of 15torr.

• Membrane and Water Treatment
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• v.11 no.4
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• pp.247-255
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• 2020

Sand filter is a key unit process for particle removal in water purification treatments. Its long-standing use is due to on-site customized retrofit. Proper selection of filter media is one of the retrofit approaches to improve filter performance. This study described a series of controlled laboratory column tests and examined the effects of media property on filtration and backwash. When sand media of 0.51 mm in effective size was replaced by sand of 0.60 mm, the filter run increased up to 5 times in the given bed depth. The change of media property required an increase of backwash rate by 0.05 m/min to satisfy the requirement of bed expansion, more than 20%. When the anthracite was changed with lower effective size and uniformity coefficient, correlation with sand in the filter bed could be satisfied within the permissible error between media and bulk characteristics. Besides, this selection resulted in a well-stratified configuration of media layers after bed expansion. The column study showed that the correlation of property between the dual media had a significant effect on the filter productivity and backwash interval.

• Journal of Welding and Joining
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• v.29 no.3
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• pp.82-88
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• 2011

With a tendency for the application of thin magnesium alloy plates in portable electronic equipment such as cell phone and notebook PC, there is a requirement to develop a welding technology for the lap welding of these thin magnesium alloy. This paper presents the single pulsed laser welding of AZ31B magnesium alloy. The effects of fiber types and parameters such as peak power and pulse width on laser weldability were investigated. The results show that weld defects, especially solidification crack, were always generated in the weld. These defects couldn't be controlled by the simple square pulse, but could be improved through the application of variable pulse. It is because that variable pulse has effect of solidification delay by dropping peak power gradually.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.252-252
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• 2000

The Resistance Spot Welding (RSW) has been considered as an inherently safe and reliable method far joining metals, and has been widely employed, especially in automobile body assembly shops, as a manufacturing process. In recent years, the requirement for more sophisticated quality control procedures has considerably grown in the mass production industries. The object of the application of servo control to spot welding gun is the improvement of quality control in the spot welding, one of conventional industrial areas. The important factors affecting welding qualities (shear strength, nuggest size, indentation depth) are welding current, welding time, and gun press force. Welding current and welding time are controlled by welding timer. But, the conventional welding guns using compressed air are out of control in changing gun press forces in welding process. In this paper, a servo gun welding system having a AC servo motor and a PC control system is presented. The main object of this paper is to estimate the influence of gun press force changes in the welding process (press time -> welding time -> hold time) to welding qualities, and to evaluate welding qualities in real time, by recognizing the patterns of gun press forces changed in the welding process and comparing with the standard patterns.

• Nuclear Engineering and Technology
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• v.36 no.3
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• pp.263-275
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• 2004

For the safe management of nuclear facilities, including a radioactive waste repository, data about the facility site and the surrounding environment must be collected and managed systematically. This is particularly true for a radwaste repository, which has to be institutionally controlled for a long period after closure. The objectives of this study are (1) to establish a systematical management plan for information about a radwaste repository site and its environment, and (2) to design a database management program for this information, based on the Relative Database Management System (RDBMS). The spatial data are designed by the geodatabase, which is a new object, based on the RDBMS, to manage spatial information related to the database. To meet this requirement, a new program called 'Site Information and Total Environmental data management System (SITES)' is being developed. The scope that produced from the first step of the present study for development of the SITES is introduced. The database is designed to combine spatial and attribute data, and is designed for the establishment of the Geographic Information System (GIS). The hardware and software systems are designed with consideration given to the total data management of the items within the radioactive environment.

• Journal of the Korean Operations Research and Management Science Society
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• v.28 no.2
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• pp.75-89
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• 2003

Media Access Control (MAC) Protocol in IEEE 802.11 Wireless LAN standard supports two types of services, synchronous and asynchronous. Synchronous real-time traffic is served by Point Coordination Function (PCF) that implements polling access method. Asynchronous nonreal-time traffic is provided by Distributed Coordination Function (DCF) based on Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol. Since real-time traffic is sensitive to delay, and nonreal-time traffic to error and throughput, proper traffic scheduling algorithm needs to be designed. But it is known that the standard IEEE 802.11 scheme is insufficient to serve real-time traffic. In this paper, real-time traffic scheduling and admission control algorithm is proposed. To satisfy the deadline violation probability of the real time traffic the downlink traffic is scheduled before the uplink by Earliest Due Date (EDD) rule. Admission of real-time connection is controlled to satisfy the minimum throughput of nonreal-time traffic which is estimated by exponential smoothing. Simulation is performed to have proper system capacity that satisfies the Quality of Service (QoS) requirement. Tradeoff between real-time and nonreal-time stations is demonstrated. The admission control and the EDD with downlink-first scheduling are illustrated to be effective for the real-time traffic in the wireless LAN.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.8
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• pp.729-734
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• 2015

Improvement in the control strategy for continuous casting is a crucial requirement to enhance the slab's quality and to increase productivity. The mold oscillator adopts the dual cylinders due to its heavy weight, so the synchronized motion of two cylinders is an important aspect when precise control is needed. The conventional method uses the master-slave control applied to the valve input reference, but the synchronization performance should still be improved. This paper proposes a novel synchronization algorithm for dual cylinders used in a mold oscillator. The master-slave concept is applied to the target reference position, that is, the slave target reference position is controlled to match the slave cylinder's position with the master cylinder's position. In the simulation based on a Simulink model, the proposed algorithm shows a better synchronization performance in aspect of the mean of the absolute error and the peak synchronization error.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.05a
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• pp.59-62
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• 2000

In cope with insufficient agricultural labor and requirement of high quality product Hydroponics is a really good method. It makes the high density agriculture possible and all the growing environments controllable. So its research is so much progressing to maximize the quantity and quality of farm products. Furthermore, the big progress, in the research of a future agriculture, is systematically conducted for the automatic controlled system. In this paper, a new approach to the automation of the cultivation in a green house is suggested and a practical automatic control cultivation system is implemented. To automatically control and optimize the very nonlinear and time-varying growth of farm products, a hybrid strategy(FECA; Fuzzy Expertized Control Algorithm) is proposed which serially combines a fuzzy expert system with the fuzzy logic control. The fuzzy expert system(FMES; Fuzzy Model-based Expert System) is intended to overcome the non-linearity of the growth of farm products. The part of fuzzy controller is incorporated to solve the time-variance of the growth of farm products. Finally, the efficiency and the effectiveness of the implemented agricultural automation system is presented through the cultiviation results.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2992-2994
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• 2000

In cope with insufficient agricultural labor and requirement of high quality product Hydroponics is a really good method. It makes the high density agriculture possible and all the growing environments controllable. So its research is so much progressing to maximize the quantity and quality of farm products. Furthermore, the big progress, in the research of a future agriculture. is systematically conducted for the automatic controlled system. In this paper, a practical automatic control cultivation system is implemented. To automatically control and optimize the very nonlinear and time-varying growth of farm products, a hybrid strategy(FECA: Fuzzy Expertized Control Algorithm) is proposed which serially combines a fuzzy expert system with the fuzzy logic control. The fuzzy expert system (FMES: Fuzzy Model-based Expert System) is intended to overcome the non-linearity of the growth of farm products. The part of fuzzy controller is incorporated to solve the time-variance of the growth of farm products. Finally. the efficiency and the effectiveness of the implemented agricultural automation system is presented through the cultivation results.