• 전자공학회논문지A
• /
• 제30A권11호
• /
• pp.1-10
• /
• 1993

A Study on New Digital In this paper, we propose a new Angular Form Carrier Recovery Loop(AFCR loop) for PSK modulation technique. AF CR loop includes detected angle symbol and Multi Level Hardlimiter. Using zero crossing DPLL, we model 1st 2nd AF CR loop, and also derive SCurve. In order to prove steady state operation of AF CR loop, we evaluate performance of this loop by Monte-Carlo and analytical simulation method. We also compare the performance of AF CR loop to that of other loop in terms of acquisition, S-Curve, and RMS jitter. From the comparison result, we verify that the performance of AF CR loop operates well in steady state.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2002년도 춘계학술대회 논문집
• /
• pp.62-65
• /
• 2002

A dieless forming system which consists of hydraulic punch elements and elastomer/fluid pads, was developed for sheet metal forming. 2-D curved surface forming was carried out using open-loop, closed-loop, and repeated forming method. Closed-loop exhibited higher decision than open-loop forming. Repeated forming also showed reduced spring back and possibility of high precision.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
• /
• pp.184-188
• /
• 2001

In this paper, a new fully digital control method for single-phase UPS inverter, which is based on the double control loop such as the outer voltage control loop and inner current control loop, is proposed. The inner current control loop is designed and implemented in the form of internal model control and takes the presence of computational time-delay into account. Therefore, this method provides an overshoot-free reference-to-output response. In the proposed scheme, the outer voltage control loop employing P controller with resonance model implemented by a DSP is introduced. The proposed resonance model has an infinite gain at resonant frequency, and it exhibits a function similar to an integrator for AC component. Thus the outer voltage control loop causes no steady state error as regard to both magnitude and phase. The effectiveness of the proposed control system has been demonstrated by the simulation and experimental results respectively.

• 전기학회논문지
• /
• 제58권7호
• /
• pp.1281-1286
• /
• 2009

As a general radial configuration of power distribution system, the various researches have being studied to change a radial configuration to network one such as smart, intelligent and micro grid for loop operation. If a radial configuration changes to network, protective coordination comes to the biggest problem. When a typical protective algorithm is applied to loop distribution system protection, the interrupted section is expanded, therefore, reliability grows worse. This paper presents the new protective method being able to apply to loop distribution system with Distribution Automation System (DAS) which separate the minimal faulted section. Through contingency analysis of the sustained and momentary fault, we analyzed the influence for radial configuration and loop configuration using interrupted area and proved the effectiveness of proposed method.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
• /
• pp.1428-1431
• /
• 1996

This paper proposes an anti-swing control law for a 2 degrees of freedom overhead crane. The dynamic model of a 2 degrees of freedom crane is highly nonlinear and coupled. The model is linearized and decoupled for each degree of freedom of the crane for small motions of the load about the vertical. Then a decoupled anti-swing control law is designed for each degree of freedom of the crane based on the linearized model. The control law consists of a position control loop and an swing angle control loop. The position loop,. is designed based on the loop shaping method and the swing angle loop is designed via the root locus method. Finally, the proposed anti-swing control law is implemented and evaluated on a 2 degrees of freedom prototype crane.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2001년도 학술논문발표회
• /
• pp.52-57
• /
• 2001

In order to control hydration heat in mass concrete, pipe cooling method has been widely used. The pipe cooling method leads to the decrease of curing period by lagging materials as well as the decrease of temperature difference between center and surface of mass concrete member, There are two methods in the pipe cooling system, which are open loop system and closed loop system. However open loop pipe cooling system cannot be applied to the mass concrete structures when cooling water supply is difficult. To control hydration heat of high strength mass foundation in the central area of city, closed loop pipe cooling system was developed to solve the cooling water supply. This paper reports the performance results of hydration heat control with closed loop pipe cooling system.

• 전자공학회논문지D
• /
• 제34D권9호
• /
• pp.7-14
• /
• 1997

A rigorous analysis method of electromagentic scattering from frequency selective surface with gridded square loop elements in case of oblique incident and arbitrary polarization is presented, which uses the roof-top subdomain basis function. The frequency response and polarization characteristics of the reflected wave and the transmitted wave for various widths of the grid and the conductor square loop, and for the various gaps between the grid and the conductor square loop, and for the various gaps between the grid and square loop is investigated. To confirm the validity of presented method, frequency selective surfaces with gridded square loop elements are fabricated with honeycomb structures, calculate dvalues for the frequency response of the reflected wave and the transmitted wave for arbitrary incident angle and polarization are compared with measured values.

• 대한전기학회논문지:전력기술부문A
• /
• 제48권8호
• /
• pp.972-979
• /
• 1999

QFT(Quantitative Feedback Theory) is a very practical design technique that emphasizes the use of feedback for achieving the desired system performance tolerances in despite of plant uncertainty and disturbance. The fundamental concept of QFT is a loop shaping procedure that a suitable controller can be found by shaping a nominal loop transfer function. The loop shaping synthesis involves the identification of a structure and the specialization of parameter optimization of a desired system. This paper presents an improved loop shaping approach of QFT with model validation using GA(Genetic Algorithm). The method presented in this paper removes the problems of iterative operation, transformation error, and model validation in the conventional methods without consideration of frequency domain.

• 제어로봇시스템학회논문지
• /
• 제18권6호
• /
• pp.546-554
• /
• 2012

This paper suggests a design method of an improved phase control loop for tracking resonant frequency of solid type precision resonant gyroscope. In general, a low cost MEMS gyroscope adapts the automatic gain control loops by taking a velocity feedback configuration. This control technique for controlling the resonance amplitude shows a stable performance. But in terms of resonant frequency tracking, this technique shows an unreliable performance due to phase errors because the AGC method cannot provide an active phase control capability. For the resonance control loop design of a solid type precision resonant gyroscope, this paper presents a phase domain control loop based on linear PLL (Phase Locked Loop). In particular, phase control loop is exploited using a higher order PLL loop filter by extending the first order active PI (Proportion-Integral) filter. For the verification of the proposed loop design, a hemispherical resonant gyroscope is considered. Numerical simulation result demonstrates that the control loop shows a robust performance against initial resonant frequency gap between resonator and voltage control oscillator. Also it is verified that the designed loop achieves a stable oscillation even under the initial frequency gap condition of about 25 Hz, which amounts to about 1% of the natural frequency of a conventional resonant gyroscope.

• Structural Engineering and Mechanics
• /
• 제18권3호
• /
• pp.331-342
• /
• 2004

The vibration control problem of structures with random parameters is discussed, which is approximated by a deterministic one. A method for calculating the standard deviations of eigenvalues of the closed-loop systems is presented by using the random perturbation. The method presented in this paper will not require the distribution function of the random parameters of the systems other than their means and variances. Similarly, the distribution function of the random eigenvalues will not be computed other than their means and variances. The standard deviations of eigenvalues of the uncertain closed-loop systems can be used to estimate the stability robustness. The present method is applied to a vibration control system to illustrate the application. The numerical results show that the present method is effective.