• Honam Mathematical Journal
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• v.37 no.2
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• pp.265-267
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• 2015

Let G be a cyclic group of prime power order. There is a natural embedding of $\mathbb{Z}$[G] into a product of rings of integers of cyclotomic fields. In this paper we determine the image of powers of the augmentation ideal.

• Honam Mathematical Journal
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• v.36 no.1
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• pp.33-41
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• 2014

Ko(2013, JIA 2013:473) discussed complete convergence for weighted sum of martingale difference field when all indices have the same powers in the normalization. In this paper we generalize this law to the case where different indices have different powers in the normalization.

• Korean Journal of Mathematics
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• v.28 no.2
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• pp.191-203
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• 2020

Any powers of 11 are easily obtained from the Pascal triangle. In this work we study powering and negative powering of any k digit integers by means of certain arithmetic tables.

• Bulletin of the Korean Mathematical Society
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• v.36 no.1
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• pp.161-169
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• 1999

Generalized nonnegative trigonometric polynomials are defined as the products of nonnegative trigonometric polynomials raised to positive real powers. The generalized degree can be defined in a natural way. We improve and extend the large sieve involving pth powers of trigonometric polynomials so that it holds for generalized trigonometric polynomials.

• Communications of the Korean Mathematical Society
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• v.25 no.2
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• pp.215-224
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• 2010

Generalized nonnegative polynomials are defined as products of nonnegative polynomials raised to positive real powers. The generalized degree can be defined in a natural way. In this paper we extend quadrature sums involving pth powers of polynomials to those for generalized polynomials.

• Journal of the Korean Mathematical Society
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• v.50 no.3
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• pp.543-555
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• 2013

We consider powers of lexsegment ideals with a linear resolution (equivalently, with linear quotients) which are not completely lexsegment ideals. We give a complete description of their minimal graded free resolution.

• Journal of Soil and Groundwater Environment
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• v.8 no.4
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• pp.21-26
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• 2003

Hwang and Powers (2003) developed a simple model for estimating water retention characteristic (WRC) directly from particle-size distribution (PSD) data, by applying a lognormal distribution law to both PSD and pore-size distribution. The objective of this work was to determine if the performance of the model developed by Hwang and Powers (2003) would be affected by soil texture. The results of this research proved that the performance of the model was indeed affected by soil texture. In particular, its performance diminished with increases in the fine particle fractions. Also, the nonlinear model, which assumes a nonlinear relation between particle-size and pore-size, performed better than the linear model, regardless of soil texture classes.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.391-393
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• 2000

This paper presents an new algorithm for the economic load dispatch considering the reliability level constraints of composite power system under deregulated electricity market. It is the traditional ELD problem that generation powers have been dispatched In order to minimize total fuel cost subjected to constraints which sum of powers generated must equal the received load and no violating lower and upper limit constraints on generation. Under deregulated electricity market, however, generation powers of a pool have to be reallocated newly in order to satisfy the reliability differentiated level required at a load point because of a reliability differentiated electricity service which is a part of the priority service. In this study, new economic load dispatch algorithm for reallocating the generation powers of a pool in order to satisfy the reliability differentiated level under deregulated competitive electricity market is proposed. The uncertainties of not only generators but also transmission lines are considered fer the reliability evaluation. The characteristics and effectiveness of this methodology are illustrated by the case studies on MRBTS and IEEE-RTS.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.3
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• pp.219-228
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• 2000

In order to evaluate the applicability of thermosyphon as an equipment of heat transfer to the case where natural of low temperature and low density is necessary and to propose the possibility of using natural energy being clean and inexhaustible, a thermosypon using methanol as working fluid was constructed and its transfer characteristics were analysed. The wall temperature of the thermosyphon was maintained relatively uniform after rapid increase until after being heated about ten minutes regardless of the level of input powers to the evaporating section. Inner pressure of the thermosyphon increased rapidly until after ten minutes, and then increased slowly depending on the level of input power. But heat transfer coefficient of the condensible section decreased in inverse proportion to input powers of 250~300W, showing $1008.3{\sim}829.8W/m^2{\cdot}^{\circ}C$. For the input powers of the thermosyphon within the range of 100~250W, heat transferred and heat flux increased relatively linearly showing, in the case of input powers of 250~300W, heat transfer efficiency considerable increased, showing 63.8%.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.22-27
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• 2012

Correct and fast detection of a micro-grid (MG) islanding is essential to the MG since operation, control and protection of the MG depend on an operating mode i.e., an interconnected mode or an islanding mode. When islanding occurs, the frequency of the point of common coupling (PCC) is not the nominal frequency during the transient state owing to the frequency rise or drop of generators in the MG. Thus, the active and reactive power calculated by the frequency domain based method such as Fourier Transform might contain some errors. This paper proposes an islanding detection algorithm for the MG based on the instantaneous active and reactive powers delivered to the dedicated line in the time domain. During the islanding mode, the instantaneous active and reactive powers delivered to the dedicated line are constants, which depend on the voltage of the PCC and the impedance of the dedicated line. In this paper, the instantaneous active and reactive powers are calculated in the time domain and used to detect islanding. The performance of the proposed algorithm is verified under various scenarios including islanding conditions, fault conditions and load variation using the PSCAD/EMTDC simulator. The results indicate that the algorithm successfully detects islanding for the MG.