• Journal of IKEEE
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• v.3 no.1 s.4
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• pp.39-49
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• 1999

This paper describes a 1 GHz, low-phase-noise CMOS fractional-N frequency synthesizer with an integrated LC VCO. The proposed frequency synthesizer, which uses a high-order delta-sigma modulator to suppress the fractional spurious tones at all multiples of the fractional frequency resolution offset, has 64 programmable frequency channels with frequency resolution of $f_ref/64$. The measured phase noise is as low as -110 dBc/Hz at a 200 KHz offset frequency from a carrier frequency of 980 MHz. The reference sideband spurs are -73.5 dBc. The prototype is implemented in a $0.5{\mu}m$ CMOS process with triple metal layers. The active chip area is about $4mm^2$ and the prototype consumes 43 mW, including the VCO buffer power consumption, from a 3.3 V supply voltage.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2079-2086
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• 2006

A fundamental study for developing a fault diagnosis system of a pump is performed by using neural network. Acoustic signals were obtained and converted to frequency domain for normal products and artificially deformed products. The neural network model used in this study was 3-layer type composed of input, hidden, and output layer. The normalized amplitudes at the multiples of real driving frequency were chosen as units of input layer. And the codes of pump malfunctions were selected as units of output layer. Various sets of teach signals made from original data by eliminating some random cases were used in the training. The average errors were approximately proportional to the number of untaught data. Neural network trained by acoustic signals can detect malfunction or diagnose fault of a given machine from the results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1194-1197
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• 2004

High temporal-resolution and accurate measurement of skin impedance locus provides useful data for the identification of the physiological/psychological changes and also the identification of acupuncture point. An impedance spectroscopy method using digitally constructed current waveform consisting of many frequency components (multiples of 1Hz) was reported3. The time resolution of the method depends on the lowest frequency used in the waveform construction, and therefore, the measurement would be faster if the lowest frequency is the higher. However, it was not clear that how many and how low frequencies must be used for the estimation of the skin impedance parameters from which the impedance locus can be drawn. This study shows the relationship between the estimation error of the impedance parameters and the frequency coverage of the spectroscopy. The results of this study are expected to serve as the reference of the frequency selection in the impedance spectroscopy.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.7
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• pp.621-626
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• 2001

The flow induced noise of the cross-flow fan with uniform/random pitch blades is predicted by computational methods. With the time dependent surface pressure data obtained by solving the incompressible Navier-Stokes equations in moving coordinates, the acoustic pressure is predicted by the Ffowcs Williams-Hawkings equation. The positions of the blade noise source are identified through an investigation of the acoustic pressure history induced by one blade, and it is confirmed that the dominant noise source is near the stabilizer. Since the acoustic pressure of the random pitch fan fluctuates according to the blade passin, the dominant BPF noise of the uniform pitch fan is modulated into some reduced discrete noises which have multiples of a 50Hz difference from BPF.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1419-1421
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• 1999

CADPAD program has been used as a distribution planning tool in KEPCO since 1989. In recent we've been upgraded the I/O modules. Now we analyze the key algorithm of FEEDERSITE module. The objective function is represented by the sum of the multiples of Power flow and cost. To minimize the objective function, it is used to Linear Programming algorithm. We will show this algorithm in this paper.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.319-320
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• 2008

In this paper, we propose a new frequency offset estimation algorithm for DBO-CSS which is a standard for wireless personal area network (WPAN). In DBO-CSS, there can be several integer multiples of $2{\pi}$ in the phase rotation caused by the frequency offset because of the long time difference between the samples of differential relation and the high permissible frequency offset of the crystal oscillators between the transmitter and the receiver. In this paper, we propose an estimation algorithm by using the relationships of each sub-chirp signals to find the integer part without phase ambiguity.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.1
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• pp.87-91
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• 2001

On patients with disorder of hematopoiesis such as leukemia, aplastic anemia, MDS(Myelodisplastic Syndromes), removal of infectious foci prior to the BMT(Bone Marrow Transplantation) is a necessity and what is more, there is no sufficient time to control the infections because the chemotherapy for BMT should be started as soon as possible. And the transfusion should be minimized to prevent the alloimmunization. In those reasons, oral & maxillofacial surgeons are often in need of multiple extractions, and should take into consideration the possibility of complications after multiples extractions such as infection, severe bleeding because those situations can be fatal on patients with disorder of hematopoiesis. We present our experience in multiple extractions on 30 patients with disorder of hematopoiesis referred from Catholic Hematopoiesis Stem Cell transplantation Center at St. Mary's Hospital, The Catholic University of Korea.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.6
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• pp.748-754
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• 1999

The acoustic performance of reactive type single expansion chamber can be calculated theoretically by plane wave theory. But higher order modes should be considered to widen the frequency range. Munjal has suggested the method for analyzing the acoustic properties of simple expansion chamber with taking into consideration of higher order mode of inlet/outlet. But his method cannot predict the acoustic properties exactly when the dimensions of inlet/outlet and expansion chamber have not integer multiples. In this paper the new method was suggested to overcome the shortcomings of Munjal's method The predictions by this method were also compared with those by the finite element method.

• Communications of the Korean Mathematical Society
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• v.32 no.4
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• pp.865-874
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• 2017

In the theory of hypergeometric and generalized hypergeometric series, classical summation theorems have been found interesting applications in obtaining various series identities for ${\Pi}$, ${\Pi}^2$ and ${\frac{1}{\Pi}}$. The aim of this research paper is to provide twelve general formulas for ${\frac{1}{\Pi}}$. On specializing the parameters, a large number of very interesting series identities for ${\frac{1}{\Pi}}$ not previously appeared in the literature have been obtained. Also, several other results for multiples of ${\Pi}$, ${\Pi}^2$, ${\frac{1}{{\Pi}^2}}$, ${\frac{1}{{\Pi}^3}}$ and ${\frac{1}{\sqrt{\Pi}}}$ have been obtained. The results are established with the help of the extensions of classical Gauss's summation theorem available in the literature.

• Bulletin of the Korean Mathematical Society
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• v.55 no.5
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• pp.1491-1501
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• 2018

Polynomials with all the coefficients in {0, 1} and constant term 1 are called Newman polynomials, whereas polynomials with all the coefficients in {-1, 1} are called Littlewood polynomials. By exploiting an algorithm developed earlier, we determine the set of Littlewood polynomials of degree at most 12 which divide Newman polynomials. Moreover, we show that every Newman quadrinomial $X^a+X^b+X^c+1$, 15 > a > b > c > 0, has a Littlewood multiple of smallest possible degree which can be as large as 32765.