• Proceedings of the Acoustical Society of Korea Conference
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• 1993.06a
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• pp.68-72
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• 1993

A method to measure the distortions of the loudspeaker at low frequencies without an anechoic chamber is proposed. This method utilizes the fact that the n-th harmonic distortion outside the enclosure is boosted by 40log n dB compared to that inside the enclosure. By compensating for the effect of standing waves occuring inside the enclosure, it is possible to predict the distortions for wide frequency ranges below the first break-up frequency of the diaphragm. The method is applicable to the intermodulation distortion as well.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.444-446
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• 1994

This paper describes the design of a digital multifunction controller for the intelligent high voltage customer switchboard and proposes a relaying algorithm for high impedance faults using back-propagation neural network. The hardware design uses the three microprocessors and global memory architecture to achive real time operation and control 4 feeders. The controller uses a 64-point radix-4 DIF FFT algorithm to measure the harmonic and relay parameters. Synthesized fault current waveforms are used to train and test the back - propagation network.

• School Mathematics
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• v.3 no.2
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• pp.281-294
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• 2001

As a measure of the center of data, arithmetical mean, median, mode, harmonic mean and geometric mean are generally used. Students must learn qualitative aspect of average values as well as its calculation for its adequate use. As the result of the learning, they should be able to select the appropriate average value according to the characteristic of data and problem context. For this object, the historical origin and visual interpretation of average values were introduced in this paper. And to help teaching several meanings of average values, several examples including context were suggested.

• Journal of the Korean Mathematical Society
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• v.32 no.4
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• pp.697-712
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• 1995

In the present article we consider multiparameter maximal averages and discover the crucial roles played by the number of parameters in their boundedness properties. The problem we shall deal with is initiated by Rubio de Francia [8] and will be in the spirit of an inductive extension to multiparameter cases, in which tools of our study rely on the theory of Harmonic Analysis on product spaces. Suppose that $d_\mu$ is a complex Borel measure supported on a compact subset S of $R^N$ having total mass one, $\smallint_S d_\mu = 1$.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1415-1419
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• 2004

It is essential to evaluate harmonic characteristics of high speed train using power electronics equipment such as converter-driven motor drives, battery chargers and auxiliary power supplies. The purpose of this study is to measure and analyze harmonics characteristics of korea high speed train prototype. This paper presents result of harmonics measurement and analysis of harmonics characteristics in terms of loading, speed and operation mode.

• Journal of applied mathematics & informatics
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• v.5 no.2
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• pp.525-537
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• 1998

In this paper we prove the inequality of subharmonic functions between a non-negative subharmonic function u and a smooth function $\upsilon$satisfying ｜$\upsilon(0)$\mid$\leq u(0), $\mid$\nabla \upsilon $\mid$ \leq$\mid$\nabla u $\mid$\leq c\Delta u $, where 0$\leq$c$\leq$1 is a constant. Here $\mu$is the harmonic measure on $\partial$D with respect to 0.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1461-1462
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• 2015

Based on the Kepco's standard supply terms, the customer should pay for installation the regulating device or protective device which are granted by Kepco in case the customer hinder other customer's electricity usage or it may cause the interruption because of harmonics or waveform distortion. It is necessary to consider the phase angle of voltage, current for harmonics so we can set up the measure of harmonic damages.

• Journal of the Korean Mathematical Society
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• v.34 no.3
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• pp.543-551
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• 1997

We prove a norm inequality of the form $\left\$\mid$ \upsilon \right\$\mid$ \leq (r - 1) \left\$\mid$ u \right\$\mid$_p, 1 < p < \infty$, between a non-negative subharmonic function u and a smooth function $\upsilon$ satisfying $$\mid$\upsilon(0)$\mid$ \leq u(0), $\mid$\nabla\upsilon$\mid$ \leq \nabla u$\mid$$ and $\mid$\Delta\upsilon$\mid$ \leq \alpha\Delta u$, where $\alpha$ is a constant with $0 \leq \alpha \leq 1$. This inequality extends Burkholder's inequality where $\alpha = 1$.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.20-21
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• 2003

Electronic speckle pattern interferometry has many applications in science and engineering. Among these, vibration measurement is the area where ESPI has many advantages over other techniques. We developed a stroboscopic ESPI system to measure the harmonic vibration of a piece of copper tape attached to a circular hole structure. Figure 1 shows the schematic diagram of the stroboscopic ESPI system. (omitted)

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.59-64
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• 2005

The railway electrical environment is much more severe than that found in commercial and domestic environments. However, in many instances the railway runs very close to such environments. In this paper we measure the harmonic, the strength of electromagnetic fields and the consumption energy for Korean High Speed Train and compare that with the past result and evaluate the result according to domestic and international guideline.