• Proceedings of the Korean Nuclear Society Conference
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• 2005.10a
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• pp.663-664
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• 2005

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2019.05a
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• pp.289-290
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• 2019

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.168-180
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• 2018

In order to achieve the high quality output voltage of single-phase voltage source inverters, in this paper an Adaptive Complementary Sliding Mode Control (ACSMC) is proposed. Firstly, the dynamics model of the single-phase inverter with lumped uncertainty including parameter variations and external disturbances is derived. Then, the conventional Sliding Mode Control (SMC) and Complementary Sliding Mode Control (CSMC) are introduced separately. However, when system parameters vary or external disturbance occurs, the controlling performance such as tracking error, response speed et al. always could not satisfy the requirements based on the SMC and CSMC methods. Consequently, an ACSMC is developed. The ACSMC is composed of a CSMC term, a compensating control term and a filter parameters estimator. The compensating control term is applied to compensate for the system uncertainties, the filter parameters estimator is used for on-line LC parameter estimation by the proposed adaptive law. The adaptive law is derived using the Lyapunov theorem to guarantee the closed-loop stability. In order to decrease the control system cost, an inductor current estimator is developed. Finally, the effectiveness of the proposed controller is validated through Matlab/Simulink and experiments on a prototype single-phase inverter test bed with a TMS320LF28335 DSP. The simulation and experimental results show that compared to the conventional SMC and CSMC, the proposed ACSMC control strategy achieves more excellent performance such as fast transient response, small steady-state error, and low total harmonic distortion no matter under load step change, nonlinear load with inductor parameter variation or external disturbance.

• Journal of Information Technology Services
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• v.15 no.1
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• pp.81-96
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• 2016

This study analyzes how breach fee under long-term contract and/or cap regulation on the breach fee can affect the impacts of "Mobile Device Distribution Improvement Act" on handset bundle price, average revenue per unit (ARPU), and social welfare. We conduct comparative analysis with an economic model of duopoly competition in price when users are under long-term contract and the breach fee can be regulated. The results show that the Act lowers the equilibrium prices, lower than incumbent price without the Act. Price of non-dominant Mobile Network Operator (MNO) can be lower than poaching price without the Act if significant portion of switching cost is breach fee or the market is significantly asymmetric. Under the significant circumstances, the Act can raise ARPU even though it improves social welfare. By contrast, the Act increases consumer surplus without affecting social welfare if breach fee is the only source of user's switching cost and is capped by the regulation, and more symmetric market and the stronger cap leads to higher consumer surplus.

• Journal for History of Mathematics
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• v.15 no.3
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• pp.83-93
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• 2002

We investigate a history of reseahches of a nonlinear elliptic equation with jumping nonlinearity, under Dirichlet boundary condition. The investigation will be focussed on the researches by topological methods. We also add recent researches, relations between multiplicity of solutions and source terms of tile equation when the nonlinearity crosses two eigenvalues and the source term is generated by three eigenfunctions.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.272-275
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• 2003

A mixed analytical/numerical method is developed here to solve the low Reynolds number kepsilon turbulence model. In this method the advection-diffusion part is solved numerically, while the source terms are split into two parts: one part is solved analytically and the next is solved numerically.

• Nuclear Engineering and Technology
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• v.31 no.1
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• pp.9-16
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• 1999

A 330 MWt-sized multi-purpose integral-type reactor, SMART is under development in Korea for the use of nuclear energy other than electricity generation. In this study, various radioactive source terms are estimated for SMART. SMART is different from conventional reactor concepts in operation and design. Therefore Specific Calculation method namely recurrence model is used. This model is based on the change rate in the RC radioactivity materials and operational characteristics of SMART Calculation results show tremendously increase of the levels of RC activity because no cleanup of RC and long term operation.

• Journal for History of Mathematics
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• v.15 no.2
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• pp.141-160
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• 2002

We investigate the history of the research of the existence of periodic solutions of a nonlinear wave equation with jumping nonlinearity, suggested by Mckenna and Lazer (cf. [15]). We also investigate the recent research of it; a relation between multiplicity of solutions and source terms of the equation when the nonlinearity -($bu^+$-$au^-$) crosses eigenvalues and the source term f is generated by eigenfuntions.

• Journal of the Korean Mathematical Society
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• v.58 no.6
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• pp.1433-1448
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• 2021

In the present work, we investigate a viscoelastic equation involving a logarithmic nonlinear source term. After proving the existence of solutions, we establish a general decay estimate of the solution using energy estimates and theory of convex functions. This result extends and complements some previous results of [9, 21].

• Journal of Korea Water Resources Association
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• v.38 no.2
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• pp.155-166
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• 2005

Upwind schemes are very well adapted to the discontinuous flow and have become popular for applications Involving dam break flow, transcritical Slow, etc. However, upwind schemes have been applied mainly to the idealized problems not to the natural channels with irregular geometry so far because of the error due to source terms. In this paper, the new type of upwind discretization of source terms, which uses the normalized Jacobian to discretize the source terms, is proposed. As results of tests to flows with source terms by the upwind models, the method proposed in this paper is proved as efficient and accurate. This generalized method for differencing source terms is simple and might beapplicable to diverse type of flux upwind discretization scheme in finite difference method.