• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.13 no.1
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• pp.41-53
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• 2009

A primal-dual interior point method(IPM) not only is the most efficient method for a computational point of view but also has polynomial complexity. Most of polynomialtime interior point methods(IPMs) are based on the logarithmic barrier functions. Peng et al.([14, 15]) and Roos et al.([3]-[9]) proposed new variants of IPMs based on kernel functions which are called self-regular and eligible functions, respectively. In this paper we define a new kernel function and propose a new IPM based on this kernel function which has $O(n^{\frac{2}{3}}log\frac{n}{\epsilon})$ and $O(\sqrt{n}log\frac{n}{\epsilon})$ iteration bounds for large-update and small-update methods, respectively.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1421-1428
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• 2015

The efficiency and reliability of the dual-buck inverter (DBI) were greatly improved by eliminating the shoot-through problem and optimally designing the freewheeling diode. The traditional DBI suffers from large harmonic components with low output voltage and large capacity output filter inductor. To overcome the aforementioned disadvantages, a modified DBI (MBDI) was proposed by adopting a quasi-resonant link and pulse density modulation (PDM). This paper first introduces the working principle of the MBDI and PDM, and then the selection principle of system parameters is presented. Finally, a mathematical model of the MBDIis built, and an experiment prototype is set up. Simulation and experimental results verify the correctness of the theoretical analysis and the feasibility of the scheme.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.251-254
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• 2003

In recent years, shearogrpahy has significantly improved capabilities In the areas of unbend and separation detection in tires. Although shearography has many advantages fur qualitative evaluation, the technique remains the problem of quantitative analysis of inside defects, because shearography needs several effective factors including the amount of shearing, shearine direction and induced load, which exist as barrier for the quantitative analysis of inside defects. Since the factors are highly dependent on inspectors skill and also affect the in-situ workability. The factors were optimized and the size of cracks inside of pipeline and tire has been quantitatively determined.

• Structural Engineering and Mechanics
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• v.13 no.4
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• pp.437-453
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• 2002

In this paper, dynamic stiffness and flexibility for circular membranes are analytically derived using an efficient mixed-part dual boundary element method (BEM). We employ three approaches, the complex-valued BEM, the real-part and imaginary-part BEM, to determine the dynamic stiffness and flexibility. In the analytical formulation, the continuous system for a circular membrane is transformed into a discrete system with a circulant matrix. Based on the properties of the circulant, the analytical solutions for the dynamic stiffness and flexibility are derived. In deriving the stiffness and flexibility, the spurious resonance is cancelled out. Numerical aspects are discussed and emphasized. The problem of numerical instability due to division by zero is avoided by choosing additional constraints from the information of real and imaginary parts in the dual formulation. For the overdetermined system, the least squares method is considered to determine the dynamic stiffness and flexibility. A general purpose program has been developed to test several examples including circular and square cases.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.4
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• pp.260-273
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• 2007

The wireless sensor network (WSN) nodes are required to operate for several months with the limited system resource such as memory and power. The hardware platform of WSN has 128Kbyte program memory and 8Kbytes data memory. Also, WSN node is required to operate for several months with the two AA size batteries. The MAC, Network protocol, and small application must be operated in this WSN platform. We look around the problem of memory and power for WSN requirements. Then, we propose a new computing model of system software for WSN node. It is the Atomic Object Model (AOM) with Dual Priority Scheduling. For the verification of model, we design and implement IEEE 802.15.4 MAC protocol with the proposed model.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.22 no.2
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• pp.101-113
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• 2018

The dual singular function method(DSFM) is a numerical algorithm to get optimal solution including corner singularities for Poisson and Helmholtz equations. In this paper, we apply DSFM to solve heat equation which is a time dependent problem. Since the DSFM for heat equation is based on DSFM for Helmholtz equation, it also need to use Sherman-Morrison formula. This formula requires linear solver n + 1 times for elliptic problems on a domain including n reentrant corners. However, the DSFM for heat equation needs to pay only linear solver once per each time iteration to standard numerical method and perform optimal numerical accuracy for corner singularity problems. Because the Sherman-Morrison formula is rather complicated to apply computation, we introduce a simplified formula by reanalyzing the Sherman-Morrison method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1719-1724
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• 2013

In this paper, a size-reduction technique is presented for the RFID reader antenna working at two UHF bands. To tackle the problem of size increase in multi-band applications, two resonance paths are made to occur in one geometry with a single feed. While one resonance path is combined with the other, the entire geometry is determined to guarantee the resonance at the target frequencies through the dual-band input impedance matching. The antenna performance is predicted by the full-wave simulation, and the design method is verified by observing the good agreement between the simulated and measured results. At the two frequencies, the satisfactory return loss as well as the antenna efficiency and peak gain of the far-field pattern is obtained.

• Steel and Composite Structures
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• v.35 no.3
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• pp.343-351
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• 2020

The present research deals with the multi-dual-phase-lags thermoelasticity theory for thermoelastic behavior of transversely isotropic thermoelastic thin circular plate The Laplace and Hankel transform techniques have been used to find the solution of the problem. The displacement components, stress components, and conductive temperature distribution are computed in the transformed domain with the radial distance and further determined in the physical domain using numerical inversion techniques. The effect of rotation and two temperature are depicted graphically on the resulting quantities.

• Journal of the Korean Operations Research and Management Science Society
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• v.17 no.1
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• pp.3-16
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• 1992

We present a modified Tank and Hopfield's neural network model for solving Linear Programming problems. We have found the fact that the Tank and Hopfield's neural circuit for solving Linear Programming problems has some difficulties in guaranteeing convergence, and obtaining both the primal and dual optimum solutions from the output of the circuit. We have identified the exact conditions in which the circuit stops at an interior point of the feasible region, and therefore fails to converge. Also, proper scaling of the problem parameters is required, in order to obtain a feasible solution from the circuit. Even after one was successful in getting a primal optimum solution, the output of the circuit must be processed further to obtain a dual optimum solution. The modified model being proposed in the paper is designed to overcome such difficulties. We describe the modified model and summarize our computational experiment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.10
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• pp.622-624
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• 2014

In this letter, the joint mode selection and resource allocation method is proposed for D2D communication underlaying OFDMA based cellular networks. In the proposed scheme, D2D mode possible region is determined which satisfies QoS. Then we solve the optimization problem utilizing primal-dual algorithm. The proposed scheme shows better performance than conventional schemes.