• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.1
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• pp.23-29
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• 2005

This paper presents the characteristics of leakage currents flowing through ZinC Oxide(ZnO) surge arrester blocks under mixed direct and 60 Hz alternating voltages. A mixed voltage, in which an alternating voltage is superimposed upon a direct voltage, appears on the HVDC system network. The mixed direct and alternating voltage generator with a peak open-circuit of 10 kV was designed and fabricated. The leakage currents and V-I curves for the fine and used ZnO surge arrester blocks were measured as a function of the voltage ratio k, where the voltage ratio k is defined as the ratio of the peak of alternating voltage to the peak of the mixed voltages. The resistive component in the leakage current in the low conduction region is significantly increased with increasing the voltage ratio k. The V-I characteristic curves for the mixed voltages lies between the direct and alternating characteristics, and the cross-over phenomenon in the high conduction region was appeared.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.10
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• pp.1009-1016
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• 2007

Finite element alternating method has been suggested and used effectively to obtain the fracture parameters in assessing the integrity of cracked structures. The method obtains the solution from alternating independently between the FEM solution for an uncracked body and the crack solution in an infinite body. In the paper, the finite element alternating method is extended in order to obtain the elastic-plastic stress fields of a three dimensional inner crack. The three dimensional crack solutions for an infinite body were obtained using symmetric Galerkin boundary element method. As an example of a three dimensional inner crack, a penny-shaped crack in a finite body was analyzed and the obtained elastc-plastic stress fields were compared with the solution obtained from the finite element analysis with fine mesh. It is noted that in the region ahead of the crack front the stress values from FEAM are close to the values from FEM. But large discrepancy between two values is observed near the crack surfaces.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.12
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• pp.1549-1556
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• 2004

We have deigned, fabricated and compared four different types of static chaos microfluid mixers, including the mixers using straight channel flow, microblock-induced alternating whirl flow, microchannel-induced lamination flow, and combined alternating whirl-lamination flow. Among them, the alternating whirl-lamination (AWL-type) mixer, composed of 3-D rotationally arranged microblocks and dividing microchannels fabricated by conventional planar lithography process, is effective to reduce the mixing length over wide flow rate ranges. We characterize the performance of the fabricated mixers, through the flow visualization technique using phenolphthalein solution. We verify that the AWL-type microfluid mixer shows the shortest fluid mixing length of 2.8mm∼5.8mm for the flow rate range of Re=0.26∼26 with the pressure drop lower than 5kPa. Compared to the previous mixers, requiring the mixing lengths of 7∼17mm, the AWL-type microfluid mixer results in the 60% reduction of the mixing lengths. Due to the reduced mixing lengths within reasonable pressure drop ranges, the present micromixers have potentials for use in the miniaturized Micro-Total-Analysis-Systems($\mu$TAS).

• The Korean Journal of Food And Nutrition
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• v.5 no.2
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• pp.90-98
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• 1992

This study was divised to observe the effects of defatted(by petroleum ether) Korean ginseng on the cholesterol level of Sprague-Dowley Albino male rats by alternating the diet. 130 heads of weaned rats having 83$\pm$4g of body weight were fed with each stock diets supplemented with 0.5, 1.0 and 3.0% defatted ginseng powder for 4 or 8 weeks, and after that fed with stock diet only for 8 or 4 weeks. Total cholesterol and free form cholesterol contents in serum, liver and aorta of them were determined, and compared with the each corresponding group which was fed with defatted ginseng control diet for 12 weeks. Total cholesterol and free form cholesterol contents in the serum were increased caused by the alternating diets which was fed on 0.5, 1.0 and 3.0% defatted ginseng diet for 4 and 8 weeks after being fed on stock diet for 8 and 4 weeks, conversely total cholesterol contents in the aorta were decreased by the same alternating diets. Free form cholesterol contents in the serum, liver and aorta of the group which was fed on 1.0% defatted ginseng diet 8 weeks after being fed on stock diet for 4 weeks were increased, but that of the group which was fed alternately on 3.0% defatted ginseng diet were decreased than the corresponding defatted ginseng control diet group.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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• pp.1041-1046
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• 2003

In order to improve the surface uniformity and the conduction properties of the fabricated YBCO thick films, a system that applies alternating field vertically to the EPD field has been developed for the first time and applied to the electrophoretic deposition process. The applied alternating electric field, so called Shaky Alternating Assisted Field, caused a force to be exerted on each YBCO particle and resulted in a shaking of the particle in the direction of applied electric field, accomplishing a uniform particle orientation. The usual commercial electrical power was used for the vertically applied alternating voltage and the induced electric field was 25-120 V/cm at 60Hz. The thick film fabricated by the method developed in this paper showed better surface uniformity without crack and porosity and improved film characteristics such as critical temperature (Tc,zero = 90 K) and critical current density (2354 A/$\textrm{cm}^2$), Therefore, it is expected that the shaky-aligned electrophoretic deposition method can be used to fabricate superconductor films through a simpler process and at less expense.

• The Pure and Applied Mathematics
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• v.15 no.1
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• pp.57-72
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• 2008

This paper is concerned with the numerical solutions to steady state nonlinear elliptical partial differential equations (PDE) of the form $u_{xx}+u_{yy}+Du_{x}+Eu_{y}+Fu=G$, where D, E, F are functions of x, y, u, $u_{x}$, and $u_{y}$, and G is a function of x and y. Dirichlet boundary conditions in a rectangular region are considered. We propose alternating direction shooting method for solving such nonlinear PDE. Numerical results show that the alternating direction shooting method performed better than the commonly used linearized iterative method.

• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.115-117
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• 2002

In this paper, we obtain an explicit formula of the Laplace transform of the forward recurrence time at finite time t > 0 in an alternating renewal process, by adopting a Markovian approach. As a consequence, we obtain the first two moments of the forward recurrence time.

• Bulletin of the Korean Mathematical Society
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• v.43 no.3
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• pp.611-617
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• 2006

In this paper we construct q-Genocchi numbers and polynomials. By using these numbers and polynomials, we investigate the q-analogue of alternating sums of powers of consecutive integers due to Euler.

• KIEE International Transactions on Power Engineering
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• v.5A no.4
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• pp.412-415
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• 2005

The recent requirement for faster and more frequent solutions has encouraged the consideration of parallel implementations using decentralized processors. Distributed multi-processor environments can potentially greatly increase the available computational capacity and decrease the communication burden, allowing for faster Optimal Power Flow (OPF) solutions. This paper presents a mathematical approach to implementing distributed OPF using the alternating direction method (ADM) to parallelize the OPF. Several IEEE Reliability Test Systems were adopted to demonstrate the proposed algorithm.

• Journal of applied mathematics & informatics
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• v.30 no.1_2
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• pp.93-100
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• 2012

In this paper, we present a strongly convergent parallel projection algorithm by introducing some parameter sequences for convex feasibility problem. To prove the strong convergence in a simple way, we transmit the parallel algorithm in the original space to an alternating one in a newly constructed product space. Thus, the strong convergence of the parallel projection algorithm is derived with the help of the alternating one under some parametric controlling conditions.