• 전기의세계
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• v.29 no.3
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• pp.179-184
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• 1980

This paper presents in some detail a discussion of the design of the digital control system without nonlinear elements to exhibit deadbeat performance in response to step inputs. The transfer function of digital dontroller is obtained by calculating the sequence of inputs and outputs of the digital controller for deadbeat performance. Digital controllers are designed for unity feedback multivariable systems by this method, which is well adapted for obtaining a solution by a digital computer.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.900-902
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• 1997

Stabilization of Power systems is investigated using a proportional-integral power system stabilizer(PI PSS). Time division PI PSS is examined in this paper. Two approaches are presented for determining the optimal stabilizer gains of the proposed PI PSS. Simulation results show that the proposed PI PSS yields better system dynamic performance and stability than the sub-optimal stabilizer in the sense of having greater damping in response to a step disturbance.

• Journal of the Korean Society for Railway
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• v.2 no.4
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• pp.32-39
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• 1999

A flywheel system which can compensate electric power is presented. The designed system has a capability of providing real and imaginary power instantaneously as well as storing energy. In this paper, a control algorithm is designed. The designed algorithm is to control the secondary side current of the wound rotor induction motor using voltage-based PWM inverter. The flywheel system has advantages in converter size and power quality improvement comparing to the conventional system.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.3
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• pp.485-492
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• 1994

Trajectory tracking control porblems are described for a two-link robot manipulator with artificial rubber muscle actuators. Under the assumption that the so-called independent joint control is applied to the control system, the dynamic model for each link is identified as a linear second-order system with time-lag by the step response. Two control laws such as the feedforward and the computed torque control methods, are experimentally applied for controlling the circular trajectory of an actual robot mainpulator.

• 전기의세계
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• v.17 no.1
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• pp.11-20
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• 1968

A typical type-1 positioning servomechanism is theoretically analyzed as a multirate sampled-data system which contains two or more signals sampled at different rates by the Z-transform method. And also it is analyzed as a continuous system by using the Younsei 101 Electronic Analog Computer. Comparing the solution of the multirate sampled data system with that of the continuous system to a step input, it is concluded that the response time of the output of the multirate sampled-data system is reduced by a multirate controller, the ripple between samples is lessened and all the transients are diminished within one period.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1744-1746
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• 2003

This paper represents the development of national standard (NS) for lightning impulse (LI) voltage measuring system rated 400 kV. A traceability of the NS to the international standard could be achieved by the intercomparison test with Helsinki University. According to the IEC 60060-2, a measurement uncertainty was assessed. As a result of the tests, a measurement uncertainty and step response characteristics were satisfied with the requisite for NS.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1492-1493
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• 2007

This paper represents the development of national standard(NS) for switching impulse(SI) voltage measuring system rated 500 kV. A traceability of the NS to the international standard could be achieved by the intercomparison test with PTB(Physikalisch-Technische Bundesansalt). According to the IEC 60060-2, a measurement uncertainty was assessed. As a result of the tests, the measurement uncertainty and the characteristics of step response were satisfied with the requisite for NS.

• Convergence Security Journal
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• v.12 no.1
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• pp.17-25
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• 2012

SQL Injection techniques disclosed web hacking years passed, but these are classified the most dangerous attac ks. Recent web programming data for efficient storage and retrieval using a DBMS is essential. Mainly PHP, JSP, A SP, and scripting language used to interact with the DBMS. In this web environments application does not validate the client's invalid entry may cause abnormal SQL query. These unusual queries to bypass user authentication or da ta that is stored in the database can be exposed. SQL Injection vulnerability environment, an attacker can pass the web-based authentication using username and password and data stored in the database. Measures against SQL Inj ection on has been announced as a number of methods. But if you rely on any one method of many security hole ca n occur. The proposal of four levels leverage is composed with the source code, operational phases, database, server management side and the user input validation. This is a way to apply the measures in terms of why the accident preventive steps for creating a phased step-by-step response nodel, through the process of management measures, if applied, there is the possibility of SQL Injection attacks can be.

• Journal of Distribution Science
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• v.16 no.4
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• pp.67-74
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• 2018

Purpose - Most of the amendments to the law on the improvement of the distribution structure of mobile communication terminal equipment, the fully self-sufficient system of terminals, and the separated disclosure system on the terminals are aimed at securing transparency of the distribution structure by eliminating or reducing handset subsidies. This study investigates what items are important for the purchase of mobile phones in various and rapidly changing mobile phone markets from the consumer's point of view and tries to make a strategic suggestion for future mobile distribution strategies. Research design, data, and methodology - The procedure of this study takes place in four steps. In step 1, only the SF type respondents selected for this study were extracted through MBTI analysis. In step 2, they were divided into three hierarchies for the AHP analysis and each element was arranged. In step 3, the AHP analysis was converted to a Fuzzy-AHP number using the trigonometric centroid method. This was to eliminate the ambiguity of the response by converting into a fuzzy number even if data consistency was maintained with CI value below 0.1. In step 4, the number of converted 2-layer and 3-layer was combined to derive the priority when the final handset is selected. Results - First, the highest importance among the four items in the second tier was the terminal function item, followed by brand, price, and design item. Second, in the third tier, the highest importance was level of after-sales service, followed by device price, processing speed, ease of use, usefulness, and rate system. Third, the arithmetic average of the determinant of the fuzzy function showed that processing speed, ease of use and usefulness in the function item, level of after-sales service in the brand item, and device price in the price item were the five most important factors among 16 choice factors. Conclusions - First, there will be a change in the consumption patterns of consumers who have compared distributors and dealers to purchase handsets with more subsidies. Second, it is highly likely that people will purchase new handsets only when they need to change their devices because they can not receive subsidies by switching phone brands any more.

• Computational Structural Engineering
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• v.8 no.2
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• pp.153-161
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• 1995

The dynamic instability for snapping phenomena has been studied by many researchers. There is few paper which deal with the dynamic buckling under the load with periodic characteristics, and the behavior under periodic excitation is expected the different behavior against step excitation. In this study, the dynamic direct snapping of shallow elliptic paraboloidal shells is investigated under not only step excitation but also sinusoidal and seismic excitations, applied in the up-and-down direction. The dynamic nonlinear responses are obtained by the numerical integration of the geometrically nonlinear equations of motion, and examined by the Fourier spectral analysis in order to get the frequency-dependent characteristics of the dynamic instability for various load levels. The results show that the dynamic instability phenomenon carried out from stable to unstable region reveals considerably different mechanism depending on the characteristics of excitations.