• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.9
• /
• pp.2121-2126
• /
• 2013

This paper compares radix-2 based structures for 32768-point FFT. Radix-$2^k$ structures have been widely used because the butterfly is simple and the number of multipliers can be reduced in those structures. This paper applied various radix-$2^k$ structures to 32768-point FFT that is representing ultra-long FFT. The ultra-long FFT has been studied much recently. This paper shows that the radix-$2^4$ structure is the most adequate because it shows the smallest complexity in the synthesis and the best SQNR performance. should be placed here.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.166-166
• /
• 2013

Mesoporous $SiO_2$-supported Ni catalysts (Ni/$SiO_2$ and Ni/$TiO_2$/$SiO_2$) were fabricated by atomic layer deposition (ALD), and their catalytic activity and stability were investigated in carbon dioxide reforming of methane (CRM) reaction at $800^{\circ}C$ The Ni/$SiO_2$ catalysts showed high stability as a result of confinement of Ni particles with a mean size of ~10 nm within the pores of $SiO_2$ support. Besides, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and transmission electron microscopy (TEM) results showed that the Ni nanoparticles were partially buried inside the $SiO_2$ support. The strong interaction between Ni and the $SiO_2$ support could also be advantageous for long-term stability of the catalyst. In case of the Ni/$TiO_2$/$SiO_2$ catalyst, it was found that the catalytic activity of 10 nm-sized Ni nanoparticles was not much influenced by $TiO_2$ addition.

• The Korean Journal of Pesticide Science
• /
• v.10 no.1
• /
• pp.66-68
• /
• 2006

New synthetic method of 2-mercaptobenzoxazoles and 2-mercaptobenzimidazoles was established using elemental sulfur, dichloromethane, inorganic base and catalysts in alcohol solvents. This reaction condition gave products in high yields.

• Archives of Pharmacal Research
• /
• v.15 no.1
• /
• pp.87-90
• /
• 1992

The syntheses of novel heterocyclic base modified pyrimidine nucleosides are described. 5, 6-dimethyl-4-hydroxy-3-methoxy-1-$(\beta$-D-ribofuranosyl)2(1H)-pyridinone 7 was synthesized by condensation of silylated 5, 6-dimethyl4-hydroxy-3-methoxy-2(1H)-pyridione 7 was synthesized by condensation of silylated 5, 6-dimethyl-4-hydroxy-3-methoxy-2(1H)-pyridinone with $\beta$-D-ribofuranose-1-acetate-2, 3, 5-tribenzoate in dichloroethane in the presence of Lewis acid followed by debenzoylation. The 2, 2'-anhydro-5, 6-dimethyl-2-hydroxy-3-methoxy-1-$\beta$-D-arabinofuranosyl-4-pyridinone 8 was obtained from the reaction of the free ribonucleoside 7 and diphenyl carbonate in DMF. None of these compounds showed any significant antiviral ad antitumor activities in vitro tests.

• Journal of the Korean Ceramic Society
• /
• v.22 no.3
• /
• pp.60-66
• /
• 1985

The formation mechanism of unstable alkali and its existing states in the clinker were studied. The relation of unstable alkali content vs. other water-soluble components porosity and the distributionof potassium were investigated. The results are as follows :1) Two states of unstable alkali seem to exist in clinker ie compounds of $K_2O-Al_2O_3$ system and free $K_2O$ 2) The content of water-soluble $Al_2O_3$ tends to increase with increase of unstable alkali content, 3) Most of alkalies in clinker are concentrated in liquid phase at high temperature. Therefore it is possible to make various $K_2O-Al_2O_3$ system compounds according to the content of $K_2O$ in the liquid phase of clinker. In this experiment we found out a $K_2O-Al_2O_3$ compound of high $Al_2O_3$ content (34%) and high $K_2O$ content (33%) in clinker with 1.09% unstable alkali. 4) The porosity of clinker tends to increase with increase of unstable alkali content. 5) The amount of trapped alkali vapor may increase in closed pore in the clinker with high alkali and low $SO_3$ condecent. Therefore free $K_2O$ is the condensed alkali on the wall of closed pore in the clinker.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.2050-2052
• /
• 2000

In this paper, the effect of $O_2$ concentration on NO removal and $NO_2$ generation by corona discharge from simulated flue gas was measured and estimated for the wire-plate reactor. $NO_2$ removal rate was 0$\sim$30[%] under about 3.4[%] of oxygen concentration, however, it was difficult to remove NOx over 3.4[%] of oxygen concentration. It may be due to generate $NO_2$ from $N_2$ and $O_2$ molecules and converse NO to $NO_2$ by 0 and $O_3$. Magnetic field applied to electric field in plasma was very effective for NOx removal under 2[%] of $O_2$ concentration.

• Progress in Superconductivity
• /
• v.3 no.2
• /
• pp.213-217
• /
• 2002

We have fabricated successfully single-filament composite $MgB_2$/SUS tapes, as an ultrarobust conductor type. The fabrication of the $MgB_2$/SUS tapes was performed by power-in-tube (PIT) process such as swaging and cold rolling. The critical transition temperatures $T_{c}$~38.5 K and ~36 K were observed for the sintered and the nonsintered $MgB_2$/SUS tapes, respectively In addition, the isothermal magnetization M(H) of the sintered $MgB_2$/SUS tapes was measured at temperatures T (between 5 and 50 K) in fields up to 6 T, employing a PPMS-9 (Quantum Design). The persistent current density (J$T_{P}$) values were obtained from the M(H) data, using Bean model, fur the sintered $MgB_2$/SUS tapes. The estimated values were higher than ~ 6$\times$ $10^{5}$ $A/\textrm{cm}^2$ at T = 5 K, with H : 0 G. We also investigated the cross section of the sintered tapes, by using SEM and EDX. An evidence of weak reaction on boundary between $MgB_2$ and SUS tube is found in the SEM and EDX.X.X.X.

• The Bulletin of The Korean Astronomical Society
• /
• v.41 no.1
• /
• pp.79.1-79.1
• /
• 2016

We investigated the dynamical properties of the K2-3 multi-planet system. Recently three transiting planets are discovered using the extended Kepler2 (K2) mission (Crossfield et al. 2015). We extended their preliminary stability study by considering a substantial longer integration time. Since planet mass is not known from photometry we calculated exoplanets masses using empirical mass-radius relations (Weiss & Marcy 2014). Forward numerical integration was done using the MERCURY integration package (Chambers 1999). Our results demonstrate that this system is stable over a time scale of $10^8years$. Furthermore, we investigated the dynamical effects of a hypothetical planet in the semi-major axis vs eccentricity space. For stable orbits of the hypothetical planet we calculated transit-timing variation (TTV) and radial velocity signals. We find that for a hypothetical perturber with mass 1-13 Mjup, semi-major axis 0.2 - 0.8 AU and eccentricity 0.00-0.47 the following timing signals for the planet K2-3 b is ~ 5 sec, K2-3 c is ~ 130 sec and for K2-3 d is ~ 190 sec. The radial velocity signal of the hypothetical planet is ~ 4 m/s. Using typical transit-timing errors from the K2 mission, we find that the above hypothetical planet would not be detectable. Its radial velocity signal, however, would be detectable using the APF 2.4m telescope or HARPS at the ESO/La Silla Observatory in Chile.

• Journal of the Microelectronics and Packaging Society
• /
• v.12 no.2 s.35
• /
• pp.161-166
• /
• 2005

Glass formation, thermal property and crystallization behavior were investigated in $xK_2O-(33.3-x)BaO-16.7TiO_2-50SiO_2(mole\%)$ with fresnoite($Ba_2TiSi_2O_8$) crystal by replacement BaO for $K_2O$. As x(0$\le$x$\le$20) contents increased, glass formation became easy, and crystallization temperature moved on to the low temperature. Crystal phase of the $Ba_2TiSi_2O_8$ was confirmed by XRD, and the replaced x was not effected on the formation of new crystals. The kinetics of crystallization of fresnoite were studied by applying the DTA measurements carried out at different heating rates. The average avrami exponent(n) and activation energy were changed $2.26 {\pm}0.1,\;2.03 {\pm}0.1,\;1.93{\pm}0.15$, $279 {\pm}12kJ/mole,\;302{\pm}7kJ/ mole,\;319{\pm}1kJ/mole$ according to x contents, respectively. The replaced x improved the orientation of crystal growth.

• Honam Mathematical Journal
• /
• v.32 no.3
• /
• pp.525-536
• /
• 2010

Let $X_1,X_2,\cdots$ be identically distributed $\rho$-mixing random variables with mean zeros and positive finite variances. In this paper, we prove $$\array{\lim\\{\in}\downarrow0}{\in}^2 \sum\limits_{n=3}^\infty\frac{1}{nlogn}P({\mid}S_n\mid\geq\in\sqrt{nloglogn}=1$$, $$\array{\lim\\{\in}\downarrow0}{\in}^2 \sum\limits_{n=3}^\infty\frac{1}{nlogn}P(M_n\geq\in\sqrt{nloglogn}=2 \sum\limits_{k=0}^\infty\frac{(-1)^k}{(2k+1)^2}$$ where $S_n=X_1+\cdots+X_n,\;M_n=max_{1{\leq}k{\leq}n}{\mid}S_k{\mid}$ and $\sigma^2=EX_1^2+ 2\sum\limits{^{\infty}_{i=2}}E(X_1,X_i)=1$.