• Structural Engineering and Mechanics
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• 제82권5호
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• pp.611-628
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• 2022

Energy-dissipative rocking (EDR) columns are a class of seismic mitigation device capable of dissipating seismic energy and preventing weak-story failure of moment resisting frames (MRFs). An EDR consists of two hinge-supported steel columns interconnected by steel dampers along its height. Under earthquakes, the input seismic energy can be dissipated by plastic energy of the steel dampers in the EDR column. However, the unrecoverable plastic deformation of steel dampers generally results in residual drifts in the structural system. This paper presents a proof-of-concept study on an innovative device, namely self-centring energy-dissipative rocking (SC-EDR) column, aiming at enabling self-centring capability of the EDR column by installing a set of shape memory alloy (SMA) tension braces. The working mechanism of the SC-EDR column is presented in detail, and the feasibility of the new device is carefully examined via experimental and numerical studies considering the parameters of the SMA bar diameter and the steel damper plate thickness. The seismic responses including load carrying capacities, stress distributions, base rocking behaviour, source of residual deformation, and energy dissipation are discussed in detail. A rational combination of the steel damper and the SMA tension braces can achieve excellent energy dissipation and self-centring performance.

• 대한수학회보
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• 제61권1호
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• pp.161-193
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• 2024

In this paper, we consider the asymptotic behavior of solutions for the partly dissipative reaction diffusion systems of the FitzHugh-Nagumo type with hereditary memory and a very large class of nonlinearities, which have no restriction on the upper growth of the nonlinearity. We first prove the existence and uniqueness of weak solutions to the initial boundary value problem for the above-mentioned model. Next, we investigate the existence of a uniform attractor of this problem, where the time-dependent forcing term h ∈ L²_b(ℝ; H^-1(ℝ^N)) is the only translation bounded instead of translation compact. Finally, we prove the regularity of the uniform attractor A, i.e., A is a bounded subset of H²(ℝ^N) × H¹(ℝ^N) × L²_µ(ℝ⁺, H²(ℝ^N)). The results in this paper will extend and improve some previously obtained results, which have not been studied before in the case of non-autonomous, exponential growth nonlinearity and contain memory kernels.

• Structural Engineering and Mechanics
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• 제51권1호
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• pp.141-162
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• 2014

The paper focuses on the dynamic response of a blast-invested glass-steel curtain wall supported by single-way pretensioned cables. In order to mitigate the critical components of the façade from severe structural damage, an innovative system able to absorb and dissipate part of the blast-induced stresses in the critical façade components is proposed. To improve the blast reliability of the studied glazing system, specifically, rigid-plastic and elastoplastic devices are introduced at the base and at the top of the vertical bearing cables. Several combinations and mechanical calibrations of these devices are numerically investigated and the most structurally and economically advantageous solution is identified. In conclusion, a simple analytical formulation totally derived from energetic considerations is also suggested for a preliminary estimation of the maximum dynamic effects in single-way cable-supported façades subjected to high-level blast loads.

• 한국전자통신학회논문지
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• 제11권1호
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• pp.87-92
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• 2016

Van der Pol 발진기는 비선형 제동 현상을 가진 비보존 발진기로서 높은 진폭에서의 에너지는 소산적이며 (dissipative)이고 낮은 진폭들에서는 생성되는 구조를 가진다. 본 논문에서는 Van Der Pol 발진기 모델에서 다른 거동을 확인하기 위하여 주기적 외력을 인가하고 여기에서 파라미터 변화에 따라 어떻게 리미트 사이클이 변화하는지에 대한 패턴을 확인하고자 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.215-217
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• 2002

In this paper, a new converter for utility interactive photovoltaic system is proposed, the conventional utility interactive photovoltaic system is composed of a PWM inverter and a DC converter. However, the increased switching loss and the high frequency switching noise become a problem. the control accuracy of the system is made to lower by the dead time of the switching devices. and it becomes a cause of the lower conversion efficiency. In order to resolve those problems, we applied a non- dissipative snubber circuit to a converter, which generates the single phase absolute value of sinusoidal current. the converter consists of two switching devices and one capacitor which constitute a non-dissipative snubber circuit. the proposed circuit is very useful to minimize and increase efficiency, when it is used to an utility interactive photovoltaic system. it is confirmed by simulation that the proposed converter for new photovoltaic system has stable operation and good output.

• Journal of Electrical Engineering and information Science
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• 제3권1호
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• pp.14-20
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• 1998

The resistive shunting for the fine control of a Direct Energy Transfer(DET) systems is fully developed, but the non-resistive shunting using variable size solar array segments is in progress. This paper presents the spacecraft power control through switching of solar array segments, which uses a fully regulated DET power regulation. This method eliminates a dissipative element and removes the associated design limitations which arise from the dissipative elements for radiating cooling in deep space. The switching shunt regulator comprises the switched Solar Array Shunt(SAS) modules that regulate the solar array power. These SAS modules connect/disconnect the solar array segments to/from the bus according to the loading in the main bus without significant variations in the dissipation level. In this paper, twelve segments are used in the shunting. In order to verify the basis of analysis, the computational result of an analytic loop gain is performed.

• 대한수학회지
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• 제33권3호
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• pp.693-707
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• 1996

Consider a specific class of scalar-valued reaction diffusion equations of the form $$ (1.1) u_t = \nu\Delta u + f(u), u \in R $$ where $\nu$ < 0 is viscosity parameter and $f : R \to R$ is sufficiently smooth.

• 대한수학회지
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• 제32권4호
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• pp.869-876
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• 1995

Piezo devices such as piezoceramic patches knwon as collocated rate sensor and actuators are commonly used in control of flexible structure (see, e.g., [1]) and noise reduction. Recently, Ito and Kang ([4]) developed a nonlinear feedback control synthesis for regulating fluid flow using these devices.

• Journal of applied mathematics & informatics
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• 제10권1_2호
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• pp.17-26
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• 2002

A stability analysis of a non-linear prey-predator system under the influence of one dimensional diffusion has been investigated to determine the nature of the bifurcation point of the system. The non-linear bifurcation analysis determining the steady state solution beyond the critical point enables us to determine characteristic features of the spatial inhomogeneous pattern arising out of the bifurcation of the state of the system.

• 대한화학회지
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• 제56권4호
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• pp.431-439
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• 2012

Dissipative particle dynamics (DPD) was carried out to study the nucleation and crystal growth process of $CeO_2$ nanoparticles in different alcohol aqueous solutions. The results showed that the nucleation and crystal growth process of $CeO_2$ can be classified into three stages: nuclei growth, crystal stabilization and crystal aggregation except the initial induction stage, which could be reproduced by collecting simulation results after different simulation time. Properly selecting the sizes of $CeO_2$ and water bead was crucial in the simulation system. The influence of alcohol type and content in solutions, and precipitation temperature on the particle dimension were investigated in detail and compared with the experimental results. The consistency between simulation results and experimental data verify that the simulation can reproduce the macroscopic particle aggregation process. The effect of solvent on the nucleation and crystal growth of $CeO_2$ nanoparticles are different at three stages and can not be simply described by Derjaguin-Landau-Verwey-Overbeek (DLVO) theory or nucleation thermodynamics theory. Our work demonstrated that DPD methods can be applied to study nanoparticle forming process.