• Phonetics and Speech Sciences
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• v.7 no.1
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• pp.21-26
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• 2015

The aim of this study is to synthesize pathological breathy voice and to make a cepstral peak prominence (CPP) table following breathiness ranks by cepstral analysis to supplement reliability of the perceptual auditory judgment task. KlattGrid synthesizer included in Praat was used. Synthesis parameters consist of two groups, i.e., constants and variables. Constant parameters are pitch, amplitude, flutter, open phase, oral formant and bandwidth. Variable parameters are breathiness (BR), aspiration amplitude (AH), and spectral tilt (TL). Five hundred sixty samples of synthetic breathy vowel /a/ for male were created. Three raters participated in ranking of the breathiness. 217 were proved to be inadequate samples from perceptual judgment and cepstral analysis. Finally, 343 samples were selected. These CPP values and other related parameters from cepstral analysis are classified under four breathiness ranks (B0~B3). The mean and standard deviation of CPP is $16.10{\pm}1.15$ dB(B0), $13.68{\pm}1.34$ dB(B1), $10.97{\pm}1.41$ dB(B2), and $3.03{\pm}4.07$ dB(B3). The value of CPP decreases toward the severe group of breathiness because there is a lot of noise and a small quantity of harmonics.

• Journal of the Korean Chemical Society
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• v.47 no.6
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• pp.591-596
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• 2003

Aminothienopyridazines 1a, b and aminothienocoumarin 2 condensed with DMFDMA to yield amidines 3a, b and 4. These compounds reacted with N-phenylmaleimide to yield 9 and 10. On the other hand reacting 3a, b, 4, 18, 19 and 20 with maleic anhydride afforded only the formylated derivatives 5a, b, 6, 21, 22 and 23 respectively. The reaction of 3a, b with diethyl fumarate afforded 11, formed most likely via hydrolysis of the amidine 14 during working up the reaction mixture. Irradiation of N-phenylmaleimide in microwave oven afforded [2+2] and [2+2+2] cycloaddition product.

• Korean Journal of Materials Research
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• v.15 no.12
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• pp.824-828
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• 2005

In this study the effect of the content of $TiB_2$ on wear properties was investigated. $Cu-TiB_2$ composites have been fabricated by hot extrusion. Sliding wear tests were peformed by a pin-on-disk type wear test machine under dry condition and loads varied with from 20N to 80N at sliding speed 3.5Hz. The test results showed that the wear losses and the friction coefficients decreased with increasing $Cu-TiB_2$ volume fraction and increasing the size of $Cu-TiB_2$ particle. Wear property of $10{\mu}m,\;5 vol\%\; TiB_2$ specimen was excellent all of the wear specimens. It is thought that the increase of plastic flow resistivity due to uniform distribution of $10{\mu}m,\;5 vol\%\; TiB_2$ wear specimen would improve wear property. The worn surface and wear debris were examined by optical microscope and scanning electron microscope.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.10
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• pp.824-831
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• 2013

The delta driven GMSK is a modulation scheme to generate the gaussian pulse by the bipolar delta signal and to modulate the phase function with the differential gaussian pulse between $+T_b/2$ and $-T_b/2$. The demodulation of delta driven GMSK differs from conventional GMSK schemes. This paper proposed a demodulation with the differential phase detector at the end of each bit interval. A designed detector then finds the one of the possible region by hard decision, in which the phase difference lies. Finally the binary data can be recovered by state transition process. Through the BER simulation for AWGN channel, it was found that the proposed demodulation effected by the run length of binary data. The simulated BER degradation of about 2[dB] was analyzed, as compared to the theoretical coherent demodulation with $BT_b$=0.3.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1053-1058
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• 2021

This paper presents the multi-band mixer which converts a X-, K- and Ka-band adaptively by adjusting the gate-bias voltage of an active device. The proposed mixer presented a conversion loss of -10 dB at -0.8 V gate-bias voltage for X-band, a conversion loss of -9 dB at -0.3 V gate-bias voltage for K-band and for Ka-band, a conversion loss of -7 dB at -0.2 V gate-bias voltage under the LO power of +6.0 dBm. The 1dB compression point (P1dB) is +0.5 dBm for all band.

• Progress in Superconductivity and Cryogenics
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• v.8 no.1
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• pp.1-4
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• 2006

The $MgB_2$ tapes with several metal powder addition were fabricated by PIT method with or without heat treatment. The $J_c$ value of $5.600A/cm^2$ and $16.000A/cm^2$ at 4.2 K and 5 T were obtained for the $MgB_2$ tape and 10 vol % of Cu added $MgB_2$ tape without heat treatment respectively. The $J_c$ value of $8.000A/cm^2$ and $35,000A/cm^2$ at 4.2 K and 5 T were obtained for the $MgB_2$ tape and 10 vol. % of Al added $MgB_2$ tape with heat treatment, respectively. The $J_c-B$ curve shows enhancement in $J_c$ under magnetic field. which suggests enhancement in workability and grain connectivity with several metal powder addition.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1757-1763
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• 2009

The composites were fabricated by adding 0, 15, 20, 25[vol.%] Zirconium Diboride(hereafter, $ZrB_2$) powders as a second phase to Silicon Carbide(hereafter, SiC) matrix. The physical, mechanical and electrical properties of electroconductive SiC ceramic composites by Spark Plasma Sintering(hereafter, SPS) were examined. Reactions between ${\beta}-SiC$ and $ZrB_2$ were not observed in the XRD analysis. The relative density of mono SiC, SiC+15[vol.%]$ZrB_2$, SiC+20[vol.%]$ZrB_2$ and SiC+25[vol.%]$ZrB_2$ composites are 90.93[%], 74.62[%], 74.99[%] and 72.61[%], respectively. The XRD phase analysis of the electroconductive SiC ceramic composites reveals high of SiC and $ZrB_2$ and low of $ZrO_2$ phase. The lowest flexural strength, 108.79[MPa], shown in SiC+15[vol.%] $ZrB_2$ composite and the highest - 220.15[MPa] - in SiC+20[vol.%] $ZrB_2$composite at room temperature. The trend of the mechanical properties of the electroconductive SiC ceramic composites moves in accord with that of the relative density. The electrical resistivities of mono SiC, SiC+15[vol.%]$ZrB_2$, SiC+20[vol.%]$ZrB_2$ and SiC+25[vol.%]$ZrB_2$ composites are 4.57${\times}10^{-1}$, 2.13${\times}10^{-1}$, 1.53${\times}10^{-1}$ and 6.37${\times}10^{-2}$[${\Omega}$ cm] at room temperature, respectively. The electrical resistivity of mono SiC, SiC+15[vol.%]$ZrB_2$. SiC+20[vol.%]$ZrB_2$ and SiC+25[vol.%]$ZrB_2$ are Negative Temperature Coefficient Resistance(hereafter, NTCR) in temperature ranges from 25[$^{\circ}C$] to 100[$^{\circ}C$]. The declination of V-I characteristics of SiC+20[vol.%]$ZrB_2$ composite is 3.72${\times}10^{-1}$. It is convinced that SiC+20[vol.%]$ZrB_2$ composite by SPS can be applied for heater or electrode above 1000[$^{\circ}C$]

• Journal of the Korean Magnetics Society
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• v.1 no.2
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• pp.60-68
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• 1991

In compacting the melt-spun $Nd_{14}Fe_{76}Co_{4}B_{6}$ and $Nd_{10.5}Fe_{79}Co_{2}Zr_{15}B_{7}$ magnetic powders. the difference in composition induces a different behavior of closed packing rate as a function of aspect ratio of the powders. The $Nd_{10.5}Fe_{79}Co_{2}Zr_{1.5}B_{7}$ alloy having a low Co/Fe ratio (low density) shows the better green density to have an enhanced closed packing rate. An empirical power equation relating the green density with the compacting pressure was obtained such as ${\phi}(g/cm^{2})=5.2~5.6{\times}P^{0.045~0.065}(ton/cm^{2})$. The $Nd_{14}Fe_{76}Co_{4}B_{6}$ alloy having a high Nd/Fe ratio possesses much finer grain size(50~60 nm) than that of $Nd_{10.5}Fe_{79}Co_{2}Zr_{1.5}B_{7}$ alloy and shows the higher coercivity($iH_{c}=14~15kOe$). The higher Nd/Fe ratio in the melt-spun Nd-Fe-Co-B alloy, where the domain wall pinning mechanism was found to be predominant, assists the formation of Nd-rich grain boundary phase acting as a pinning site. The grain boundary ranges over $12~16\;{\AA}$ thick in the Nd-Fe-Co-B alloy while it ranges over $8~12\;{\AA}$ thick in the Nd-Fe-Co-Zr-B alloy.

• The Korean Journal of Quaternary Research
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• v.15 no.2
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• pp.75-81
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• 2001

We have analyzed the pollen sequence since the Late Glacial at Sorori Archaeological Site. The Sorori Site is an open site located at Soro-ri, Oksan-myeon, Cheongwon-gun, Chungchongbukdo. The main results are as follows: Four forest zones have been distinguished. \circled1 OS-1 zone : Pinus-Abies-Picea forest (the sub-alpine conifer forest), the Late Glacial (about 15,000~10,000yr. B.P.) ; \circled2 OS-2 zone : Pinus-Colyus forest (the mixed conifer and deciduous broad-leaved forest), R I (about 10,000 yr.B.P.) : \circled3 OS-3 zone : Alnus-Quercus forest (the cool temperate deciduous broadleaved forest), R II(about 10,000~2,000yr.B.P.) : \circled4 OS-4 zone : Pinus forest (the conifer forest), R III (about after 2,000yr.B.P.)

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.5
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• pp.452-461
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• 1997

In this paper, we present a computer-aided design(CAD) technique for minimizing the phase shift in microstrip PIN diode attenuators due to the junction capacitance in the equivalent circuit model of PIN diode. Microstrip PIN diode attenuators use the characteristics which the reactance of microstrip line changes from inductive to capacitive as the frequency sweeps across the band. Microstrip PIN diode attenuator designed utilizes the quarter-wavelength transmission line terminating with the half-moon radial stub, which is designed for negligible phase shifting effect over the intersted bandwidth. The attenuator has similar phase shift at 0 dB and 10 dB of attenuation within average $1.27^{\circ}$ between 1.2GHz and 1.9GHz. The input and output return losses between 1.4 GHz and 1.9 GHz are less than 10 dB over the attenuation range of 0 dB and 10 dB.