• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.1
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• pp.95-103
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• 1992

Laminar natural convection heat transfer from an isothermal rectangular beam attached to horizontal and vertical adiabatic plates has been studied for various aspect ratios of the beam and Grashof numbers. The local Nusselt number was increased with decreasing H/B for the constant beam width, B, and with increasing H/B for the constant beam height, H. The total mean Nusselt number of the vertical type was higher than that of horizontal type in the range of H/B.leq.0.52, but reversed in the H/B>0.52 at constant beam width. The total mean Nusselt number of the horizontal type was generally higher than that of vertical type at constant beam height. The total mean Nusselt number of the vertical type was higher than that of horizontal type in the range of H/B.leq.0.43 at constant wetted perimeter, but reversed in the H/B$\leq$0.43.

• Journal of IKEEE
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• v.15 no.4
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• pp.293-298
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• 2011

In the paper, we propose a new CMF(Constant Modulus Fourth) algorithm for WCDMA(Wideband Code Multiple Access) RF(Radio Frequency) Repeater. CMF algorithm is proposed by modifying the CMA(Constant Modulus Algorithm) algorithm and improved performances are achieved by properly adjusting step size values. The steady state MSE(Mean Square Error) performance of the proposed CMF algorithm with step size of 0.35 is about 4dB better than that of the conventional CMA algorithm. And the proposed CMF algorithm requires 400~1100 less iterations than the LMS(Least Mean Square) and NLMS(Normalized Least Mean Square) algorithms at MSE of -25dB.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3423-3426
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• 2012

Dielectric measurement on binary mixtures of Allyl chloride (ALC) with 2-Pentanone (2-PE) and 2-Hexanone (2-HE) has been carried out over the entire concentration range using Time Domain Reflectometry (TDR) technique at various temperatures in microwave frequency range of 10 MHz to 10 GHz. The static dielectric constant, excess static dielectric constant (${\varepsilon}^E_S$), effective Kirkwood correlation factor ($g^{eff}$) of binary mixtures over entire concentration range were determined to study the effect of increasing alkyl group of ketones on hetero molecular interaction. It was found that magnitude of excess static dielectric constant of mixtures increases with increase of alky group of ketones. The study reveals that the dipole moment of Allyl chloride in mixture have antiparallelism tendency where as 2-pentanone and 2-hexanone have parallelism tendency. Excess static dielectric constant is also fitted to Redlich-Kister equation to get information about rates of multimers formation.

• Journal of Communications and Networks
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• v.13 no.5
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• pp.442-448
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• 2011

It's a challenging task to design a high performance modulation for satellite and space communications due to the limited power and bandwidth resource. Constant envelope modulation is an attractive scheme to be used in such cases for their needlessness of input power back-off about 2~3 dB for avoidance of nonlinear distortion induced by high power amplifier. The envelope of Feher quadrature phase shift keying (FQPSK) has a least fluctuation of 0.18 dB (quasi constant envelope) and can be further improved. This paper improves FQPSK by defining a set of new waveform functions, which changes FQPSK to be a strictly constant envelope modulation. The performance of the FQPSK adopting new waveform is justified by analysis and simulation. The study results show that the novel FQPSK is immune to the impact of HPA and outperforms conventional FQPSK on bit error rate (BER) performance. The BER performance of this novel modulation is better than that of FQPSK by more than 0.5 dB at least and 2 dB at most.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1167-1169
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• 1999

This paper presents the new unified power flow controller(UPFC) load flow algorithm using UPFC transmission line constant model. The UPFC transmission line constant model represents a function of transmission line constant(G.B) UPFC's effect in power system. It can easily be incorporated in a load flow program. The algorithm is suited for monitoring the power system state as well as determining the magnitude and Phase angle of UPFC serial voltage source.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.1
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• pp.180-188
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• 1995

A modified Kohonen's self-organizing feature map (SOFM) algorithm which has binary reinforcement function and a constant learning rate is proposed. In contrast to the time-varing adaptaion gain of the original Kohonen's SOFM algorithm, the proposed algorithm uses a constant adaptation gain, and adds a binary reinforcement function in order to compensate for the lowered learning ability of SOFM due to the constant learning rate. Since the proposed algorithm does not have the complicated multiplication, it's digital hardware implementation is much easier than that of the original SOFM.

• Journal of the Korean Magnetic Resonance Society
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• v.8 no.2
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• pp.70-76
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• 2004

ZORA-DFT calculations of $^{11}$B EFG (electric field gradient) tensors for lithium borates, LiB$_3O_5$ (LBO) and Li$_2B_4O_7$ (LTB), were performed. The calculated values of 11B quadrupole coupling constant and asymmetry parameter are in good agreement with the experimental values. The sign of the quadrupole coupling constant for the tetrahedral boron site was deduced from the distortion from the ideal tetrahedral symmetry.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.33-33
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• 2007

In PDP industry, the dielectrics and barrier ribs have been required with low dielectric constant, low melting point and Pb-free composition due to the low power consumption, low signal delay time and the environment restriction. We were studied with $B_2O_3-Al_2O_3$-SrO glass systems about optical, thermal and dielectric properties. The glass forming region of the $B_2O_3-Al_2O_3$-SrO glass systems was narrow due to the amount of the glass former $(B_2O_3)$. The glass transition temperature (Tg) of the glasses was at $550{\sim}590^{\circ}C$. The glasses have 6~8 for the dielectric constant. Furthermore, the transmittance of the glasses was over 80% on the range of the visible ray. From the results, the glasses of the $B_2O_3-Al_2O_3$-SrO glass systems should enable to be a good candidate of the PDP devices for information display with low dielectric constant. The aim of this study is to give a fundamental result of new glass system for low dielectric constant in the information display.

• Bulletin of the Korean Mathematical Society
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• v.36 no.2
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• pp.225-231
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• 1999

Let Mf(x) be the Hardy-Littlewood maximal function on $\mathbb{R}^n$. Let $\Phi$ and $\Psi$ be functions satisfying $\Phi$(t) = ${\int^t}_0$a(s)ds and $\Psi(t)$ = ${\int^t}_0$b(s)ds, where a(s) and b(s) are positive continuous such that ${\int^\infty}_0\frac{a(s)}{s}ds$ = $\infty$ and b(s) is quasi-increasing. We show that if there exists a constant $c_1$ so that ${\int^s}_0\frac{a(t)}{t}dt\;c_1b(c_1s)$ for all $s\geq0$, then there exists a constant $c_1$ such that(0.1) $\int_{\mathbb{R^{n}}$ $\Phi(Mf(x))dx\;\leq\;c_2$ $\int_\mathbb{R^{n}}$$\Psi(c_2\midf(x)\mid)dx$ for all $f\epsilonL^1(R^n_$. Conversely, if there exists a constant $c_2$ satisfying the condition (0.1), then there exists a constant $c_1$ so that ${\int^s}_\delta\frac{a(t)}{t}dt=;\leq\;c_1b(c_1s$ for all $\delta$ > 0 and $s\geq\delta$.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.5
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• pp.50-57
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• 1994

In the non-destructive evaluation techniques using ultrasonic signal, backscattering noise from grain interface decreases the SNR of received signal. In this paper, SSP(split-spectrum processing) based on the constant FBR decomposition method has been applied to enhance the SNR. This algorithm helps to find optimal parameters of filter bank through a simple theory and has an advantage that reduce the signal processing time compared with the conventional constant bandwidth decomposition method. In this experiment, the 304 stainless steel sample is heat-treated and received ultrasonic signal is processed by SSP using the constand bandwidth decomposition method and the constand FBR decomposition method enhanced the SNR by 1.4 dB and reduced the required number of filters by 4 compared with the constant bandwidth decomposition method.