• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.2
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• pp.67-72
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• 2005

In conventional small signal stability analysis, system is assumed to be invariant and the state space equations are used to calculate the eigenvalues of state matrix. However, when a system contains switching elements such as FACTS devices, it becomes non-continuous system. In this case, a mathematically rigorous approach to system small signal stability analysis is by means of eigenvalue analysis of the system periodic transition matrix based on discrete system analysis method. In this paper, RCF(Resistive Companion Form) method is used to analyse small signal stability of a non-continuous system including switching elements. Applying the RCF method to the differential and integral equations of power system, generator, controllers and FACTS devices including switching elements should be modeled in the form of state transition equations. From this state transition matrix eigenvalues which are mapped to unit circle can be calculated.

• KIEE International Transactions on Power Engineering
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• v.5A no.4
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• pp.344-349
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• 2005

In conventional small signal stability analysis, the system is assumed to be invariant and the state space equations are used to calculate the eigenvalues of the state matrix. However, when a system contains switching elements such as FACTS equipments, it becomes a non-continuous system. In this case, a mathematically rigorous approach to system small signal stability analysis is performed by means of eigenvalue analysis of the system's periodic transition matrix based on the discrete system analysis method. In this paper, the RCF (Resistive Companion Form) method is used to analyze the small signal stability of a non-continuous system including switching elements. Applying the RCF method to the differential and integral equations of the power system, generator, controllers and FACTS equipments including switching devices should be modeled in the form of state transition equations. From this state transition matrix, eigenvalues that are mapped into unit circles can be computed precisely.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.117-120
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• 2001

Deadbeat property is well established in digital control system design, But in continuous time, it can hardly realized for it's asymtotic property. But recently japanese researchers suggested serveral method for continuous time deadbeat property. They use delay elements In polynomials and established for the deadbeat condition. By solving this condition, unknown coefficients in polynomials with delay elements is obtained. In this paper, design method for optimal continuous time deadbeat servo system using 2nd order smooting elementsis studied. Continuous time deadbeat controller is consisted of serial integral compensator and local feedback one in state feedback loop. Determining method for damping rations and natural frequencies of smothing elements is described. By computer simulations, control inputs and system outputs are shown to have desirable property such as smoothness.

• Computers and Concrete
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• v.23 no.4
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• pp.235-243
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• 2019

The discontinuous Galerkin method (DGM) has become widely used as it possesses several qualities, such as a natural ability to dealing with discontinuities. DGM has its major success related to fluid mechanics. Its major importance is the ability to deal with discontinuities and still provide high order of approximation. That is an important advantage when simulating cracking propagation. No remeshing is necessary during the propagation, since the crack path follows the interface of elements. However, DGM comes with the drawback of an increased number of degrees of freedom when compared to the classical continuous finite element method. Thus, it seems a natural approach to combine them in the same simulation obtaining the advantages of both methods. This paper proposes the application of the combined continuous-discontinuous Galerkin method (CDGM) to crack propagation. An important engineering problem is the simulation of crack propagation in concrete structures. The problem is characterized by discontinuities that evolve throughout the domain. Crack propagation is simulated using CDGM. Discontinuous elements are placed in regions with discontinuities and continuous elements elsewhere. The cohesive zone model describes the fracture process zone where softening effects are expressed by cohesive zones in the interface of elements. Two numerical examples demonstrate the capacities of CDGM. In the first example, a plain concrete beam is submitted to a three-point bending test. Numerical results are compared to experimental data from the literature. The second example deals with a full-scale ground slab, comparing the CDGM results to numerical and experimental data from the literature.

• Proceedings of the KIEE Conference
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• summer
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• pp.342-344
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• 2004

In conventional small signal stability analysis, system is assumed to be invariant and the state space equations are used to calculate the eigenvalues of state matrix. However, when a system contains switching elements such as FACTS devices, it becomes non-continuous system. In this case, a mathematically rigorous approach to system small signal stability analysis is by means of eigenvalue analysis of the system periodic transition matrix based on discrete system analysis method. In this research, RCF(Resistive Companion Form) method is used to analyse small signal stability of a non-continuous system including switching elements'. Applying the RCF method to the differential and integral equations of power system, generator, controllers and FACTS devices including switching elements should be modeled in the form of state transition matrix. From this state transition matrix eigenvalues which are mapped to unit circle can be calculated.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.1
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• pp.67-73
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• 2002

This paper presents a new design method of optimal continuous deadbeat controller by using second-order smoothing elements. The continuous deadbeat controller is made of a serial integral compensator and a local feedback compensator introduced into the state feedback loop. The decision method of the damping factor and the natural angular frequency of the smoothing element is described. A numerical example is given to show how well input-output characteristics are improved. Especially according to the variable input and disturbance, corresponding CDBC design method is suggested. By computer simulations, control inputs and system outputs are shown to have desirable property such as smoothness.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.128-129
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• 2016

This study is to categorize the loading of multiple persons on a vertical building elements into three types to test the size of crowd pressure under each loading patterns. The loading patterns is divided under the combination of loading method and loading persons. The loading method is categorized into the method of instantaneous loading of hand on a force plate and the method of continuous loading. The loading persons has been composed of 1~5 persons under the loading patterns. The loading patterns is also divided into lateral loading, longitudinal loading, and agglomeration loading. The subject group has been composed of 12 males in 20s. The load measurement device(size 1800×600×36mm, capacity 20kN, rigidity 28kN/cm) has been designed and manufactured directly. To eliminate the difference of individual, the size of crowd pressure has been converted into the strength to weight ratio (maximum load/weight) for computation. The strength to weight ratio in lateral loading was about 0.91 under instantaneous loading and about 0.47 under continuous loading. The strength to weight ratio in longitudinal loading was about 0.65 under instantaneous loading and about 0.36 under continuous loading. The strength to weight ratio in agglomeration loading was about 0.65 under instantaneous loading and about 0.36 under continuous loading.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.171-172
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• 2012

In this study the continuous rectangular spiral hoop is used for saving cost and time, solving manpower shortage, and the quality of structures. Generally the use of continuous spiral reinforcement in reinforced concrete elements improve the strength and the ductility of the concrete. Savings in cost and time is demonstrated with the continuous rectangular spiral hoop through the mock up test of beam and column elements. In case of a 4m column element the time of rebar work decreases up to 40% compared with traditional hoop, and in case of a 8m beam the time also decreases 40%. This study present the construction method and details.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.326-326
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• 2000

Continuous time system deadbeat controller(CdbC) has been studied mainly since 1992 especially by Japan researchers. They suggested delay elements. These elements stem from the finite Laplace Transform which is the starting point in deadbeat control system design in continuous time system. Every transfer function is established by these elements. From some conditions such as internal model stability and peasibility of a CdbC controller. unknown polynomials or coefficients can be calculated. In this paper, optimal pole placement of the closed loop system is suggested. From this. a CdbC controller with lower order can be obtained which attains the same level of weighted sensitivity function's H$_{\infty}$ norm used as a measure of the robustness property as existing CdbCs.

• Structural Engineering and Mechanics
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• v.57 no.5
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• pp.861-876
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• 2016

The determination of the critical buckling load of multistory structures is important since this load is used in second order analysis. It is more realistic to determine the critical buckling load of multistory structures using the whole system instead of independent elements. In this study, a method is proposed for designating the system critical buckling load of torsion-free structures of which the load-bearing system consists of frames and shear walls. In the method presented, the multistory structure is modeled in accordance with the continuous system calculation model and the differential equation governing the stability case is solved using the differential transform method (DTM). At the end of the study, an example problem is solved to show the conformity of the presented method with the finite elements method (FEM).