• Journal of Korean Society of Water and Wastewater
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• v.20 no.3
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• pp.357-366
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• 2006

In order to compute pressure variation for a water distribution system, an expression for the friction factor as a function of Reynolds number and the relative roughness needs to be properly incorporated in computational algorithm. Considering Moody s friction variation, Developed Unsteady Network Analyzer (UNA) has been modified to match computational results with EPANET 2.0. Substantial improvement can be found in the application of Improved UNA to both an hypothetical pipeline network and a real system located in Ulsan City. Random number generator is employed to represent the uncertainty of water use in real pipeline network. Comparisons of application between EPANET 2.0 and improved UNA 2.0 indicate advantages and potentials of this approach.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1111-1116
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• 1993

In this study, we discuss the design of the expert system for the scheduling of the FMC(Flexible Manufacturing Cell) consisting of the several versatile machines. Due to the NP property, the scheduling problem of several machine FMC is very complex task. Thus we proposed the two heuritstic shceduling algorithms for solving the problem and constituted the algorithm based of solving the problem and constituted the algorithm base of ISS(Intelligent Scheduling System) using them. By the rules in the rule base, the best alternative among various algorithms in algorithm base is selected and applied in controlling the FMC. To show the efficiency of ISS, the scheduling output of ISS and the existent dynamic dispatching rule were tested and compared. The results indicate that the ISS is superior to the existent dynamic dispatching rules in various performance indexes.

• Transactions on Control, Automation and Systems Engineering
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• v.1 no.2
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• pp.147-152
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• 1999

It is an interesting area in the field of artifical intelligence to find an analytic model of cooperative structure for multiagent system accomplishing a given task. Usually it is difficult to design controllers for multi-agent systems without a comprehensive knowledge about the system. One of the way to overcome this limitation is to implement an evolutionary approach to design the controllers. This paper introduces the use of a genetic algorithm to discover a fuzzy logic controller with rules that govern emergent agents solving a pursuit problem in a continuous world. Simulation results indicate that, given the complexity of the problem, an evolutionary approach to find the fuzzy logic controller seems to be promising.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.04a
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• pp.180-189
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• 2001

In this study, recently developed unscented Kalman filter (UKF) technique is studied for identification of nonlinear structural dynamic systems as an alternative to the extended Kalman filter (EKF). The EKF, which was originally developed as a state estimator for nonlinear systems, has been frequently employed for parameter identification by introducing the state vector augmented with the unknown parameters to be identified. However, the EKF has several drawbacks such as biased estimations and erroneous estimations especially for highly nonlinear dynamic systems due to its crude linearization scheme. To overcome the weak points of the EKF, the UKF was recently developed as a state estimator. Numerical simulation studies have been carried out on nonlinear SDOF system and nonlinear MDOF system. The results from a series of numerical simulations indicate that the UKF is superior to the EKF in the system identification of nonlinear dynamic systems especially highly nonlinear systems.

• Carbon letters
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• v.25
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• pp.55-59
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• 2018

Carbon chain inserted carbon nanotubes (CNTs) have been experimentally proven having undergone pronounced property change in terms of electrical conductivity compared with pure CNTs. This paper simulates the geometry of carbon chain inserted CNTs and analyzes the mechanism for conductivity change after insertion of carbon chain. The geometric simulation of Pt doped CNT was also implemented for comparison with the inserted one. The results indicate that both modification by Pt atom on the surface of CNT and addition of carbon chain in the channel of the tube are effective methods for transforming the electrical properties of the CNT, leading to the redistribution of electron and thereby causing the conductivity change in obtained configurations. All the calculations were obtained based on density functional theory method.

• Fibers and Polymers
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• v.5 no.3
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• pp.171-176
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• 2004

Fiber fineness characteristics are important for yarn production and quality. In this paper, degummed bast fibers such as hemp, flax and ramie have been examined with the Optical Fiber Diameter Analyzer (OFDA100 and OFDA2000) systems for fiber fineness, in comparison with the conventional image analysis and the Wira airflow tester. The correlation between the results from these measurements was analysed. The results indicate that there is a significant linear co-relation between the fiber fineness measurement results obtained from those different systems. In addition, the mean fiber width and its coefficient of variation obtained from the OFDA100 system are smaller than those obtained from the OFDA2000 system, due to the difference in sample preparation methods. The OFDA2000 system can also measure the fiber fineness profile along the bast fiber plants, which can be useful for plant breeding.

• Journal of information and communication convergence engineering
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• v.10 no.2
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• pp.149-155
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• 2012

This paper presents mobile robot control architecture of hierarchical behaviors, inspired by biological life. The system is reactive, highly parallel, and does not rely on representation of the environment. The behaviors of the system are designed hierarchically from the bottom-up with priority given to primitive behaviors to ensure the survivability of the robot and provide robustness to failures in higher-level behaviors. Fuzzy logic is used to perform command fusion on each behavior's output. Simulations of the proposed methodology are shown and discussed. The simulation results indicate that complex tasks can be performed by a combination of a few simple behaviors and a set of fuzzy inference rules.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.134-137
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• 1989

A digital controller for a discrete-data control system can take many forms. For example, they can be passive RC networks, general purpose digital computers, special purpose of mini-computer, and delay lines. With the recent advent of the microprocessor, its use as a digital controller is evident. This work discusses the hardware and software development of a microprocessor-based digital controller for a discrete-data control system. A second-order, Type 1 system is implemented on an analog computer; a Intel 80-286 microprocessor is used to implemented the controller; and, output response are obtained for step, ramp, and parabolic inputs. The results demonstrate that the microprocessor has potential as a digital controller. Finally, a brief discussion on the results indicate possible areas of improvement of the controller and future investigation.

• Journal of Construction Engineering and Project Management
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• v.1 no.2
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• pp.18-27
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• 2011

Egyptian construction firms (ECF) started recently to adopt quality management system (QMS) as a way to develop and improve their performance as previous studies have shown. However, considering all the firm's aspects in a competitive way is a crucial process for the ECF's culture. This research is trying to indicate the role of the QMS implementation in measuring performance (MP) through developing a model for measuring performance at the organizational level, and to explore its impact on the organizations that adopt QMS. This model is based on specific elements and their related indicators which have been derived from national approaches and models of MP. This model determines the performance level (PL) of the organization that is measured by means of a point system. Weights of the elements in the point system considered both the elements' importance in the international models and its real practice in the ECFs. This model has been validated using another questionnaire and the majority of surveyed experts agreed that the proposed model can be applied effectively.

• Journal of the Korean Institute of Educational Facilities
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• v.1 no.1
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• pp.49-61
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• 1994

This study aims to indicate fundamental problems and also to supply basic data for the reasonable distribution of the educational facilities in an effort to build better educational environments by examining and analyzing their changing process in primary and secondary schools in accordance with the changes in school year system in the period between 1900 to 1993. The following conclusion can be drawn : a. Separation of Middle and high schools due to the change of the school year system in 1951 into 6 - 3 - 3 - 4, has had great influence upon the arrangement of the educational facilities. b. Educational facilities in primary and secondary school are expanding, but they do not meet the criterion on an appropriate scale. Especially educational facilities of high schools need to be extended.