• Publications of The Korean Astronomical Society
• /
• v.17 no.1
• /
• pp.11-14
• /
• 2002

Our examination of the relations of spherically symmetric accretion on a massive point object to viscous drag, neglecting gas pressure and using self-similar transformation, shows the behaviors of the asymptotic solutions? in the regions near to and far from the center. The viscosity reduces the free-fall velocity by the factor $(1\;+\;\zeta) ^{-1}$, and causes flattening in the density distribution. Therefore, the viscosity leads to the reduction of the mass accretion rate.

• Proceedings of the KAIS Fall Conference
• /
• 2010.05a
• /
• pp.269-272
• /
• 2010

In this paper, we propose the computation reduction methods of delta pitch search that is used in G.723.1 vocoder. In order to decrease the computational amount in delta pitch search the characteristic of proposed algorithms is as the following. First, scheme to reduce the computation amount in delta pitch search uses NAMDF. Developed the second scheme is the skipping technique of lags in pitch searching by using the threshold value. By doing so, we can reduce the computational amount of pitch searching more than 64% with negligible quality degradation.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.49 no.3
• /
• pp.177-185
• /
• 2000

In this study, the characteristics of various electricity and high resistivity ash collection were measured at superimposed nanosecond pulse energization. The pulse was generated through the hydrogen thyratron. Superimposed pulse was nanosecond duration pulse that had fast pulse rising time 100[ns], short pulse width 500∼850[ns] and pulse fall time 400∼750[ns]. The results of this study are summarized as followings; Frist, compared with the DC ESP(electrostatic precipitator), superimposed pulse ESP could induce higher peak voltage, and had the about 30[%] reduction of ESP collection area and 50∼80[%] reduction of power consumption. showing the same efficiency. Second, enhancement factor H had 1.9∼3.6 with the increase of migration velocity.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.490-495
• /
• 2001

This paper deals with an analysis and countermeasure for improving the shock performance of laptop computers. The shock analysis is carried out by using the commercial program of LS-DYNA3D. Also the analysis is verified by the measurements from modal tests and shock tests. The available countermeasures are investigated theoretically and experimentally to find the effective methods of reducing the shock acceleration on hard disk driver during one side fall test. The hard disk drive is the most sensitive part in a laptop computer. This research shows the effects of the spring constant of rubber pad, the reinforcement of mechanical parts and the location of a hard disk driver, on the shock reduction.

• Proceedings of the KAIS Fall Conference
• /
• 2001.05a
• /
• pp.82-83
• /
• 2001

Selected microbes was applied to the treatment of textile wastewater with support particles. To enhance the treatment efficiency, biological treatment was achieved as first process. Wastewater with a COD of 870 ppm and color of 1340 PtCo unit was continuously treated in a 1.8 ton capacity reactor. In the case of combined processes, the effluent COD concentration and color were 40 ppm (95.4% reduction) and 20 PtCo unit (98.5% reduction).

• Proceedings of the KAIS Fall Conference
• /
• 2004.11a
• /
• pp.280-283
• /
• 2004

Effect of H2 spillover rate as function of reduction temperature on reaction kinetics was evaluated. Reaction kinetics including yield, conversion, activation energy and selectivity of 1-butene isomerization over Pt/HxMoO/SiO were measured as reaction temperature was increased. While conversion of 1-butane was decreased, yield of iso-butene was increased. Two kinds of reaction mechanism were proposed from the change of selectivity as function of temperature.

• Proceedings of the KAIS Fall Conference
• /
• 2010.05a
• /
• pp.257-260
• /
• 2010

In this paper, we propose the computation reduction methods of LSP(Line spectrum pairs) transformation that is mainly used in CELP vocoders. In order to decrease the computational time in real root method the characteristic of four proposed algorithms is as the following. First, scheme to reduce the LSP transformation time uses mel scale. Developed the second scheme is the control of searching order by the distribution characteristic of LSP parameters. Third, scheme to reduce the LSP transformation time uses voice characteristics. Developed the fourth scheme is the control of searching interval and order by the distribution characteristic of LSP parameters. As a result of searching time, computational amount, transformed LSP parameters, SNR, MOS test, waveform of synthesized speech, spectrogram analysis, searching time is reduced about 37.5%, 46.21%, 46.3%, 51.29% in average, computational amount is reduced about 44.76%, 49.44%, 47.03%, 57.40%. But the transformed LSP parameters of the proposed methods were the same as those of real root method.

• Proceedings of the KAIS Fall Conference
• /
• 2010.05a
• /
• pp.265-268
• /
• 2010

There have been proposed two types of low bit rate vocoder upto now : One is MBE type using the spectrum modeling and another is CELP type using the hybrid coding method. CELP type vocoder has mainly studied between them. Specially, much of intensity is concentrated in CELP vocoder due to the emergence of Internet Phone and PCS in a domestic. In order to improve the speech quality in CELP vocoder, in this paper, we proposed a new spectrum analysis algorithm with variable window. In CELP vocoder, the spectrum of the synthesised speech signal is distorted because the fixed size windows is used for spectrum analysis. So we have measured the spectral leakage and in order to minimize the spectral leakage have adjusted the window size. Applying this method G.723.1 ACELP, we can get SD(Spectral Distortion) reduction 0.084(dB), residual energy reduction 6.3% and MOS(Mean Opinion Score) improvement 0.1.

• Proceedings of the KAIS Fall Conference
• /
• 2001.11a
• /
• pp.99-103
• /
• 2001

Though the research and the development in the field of machine tool was focused on high precision and high speed machine these days, traditional gear reduction device has been used to increase the cutting force which was transmitted from power source, motor In this study, analysis of 2 step gear reducer used in machining center spindle was carried out by using APM WinMachine which is commercial software for the analysis of machine element and system. For the analysis of this device, first of all, the analysis of power source and the transmitting of it were carried out. Then, machine elements like gear, shaft, bearing, and the forth, was analyzed in the view point of life time, static strength, stiffness, fatigue failure, etc. Consequently, we can estimate them and introduce new idea of the design modification of reduction device by this study.

• Ocean and Polar Research
• /
• v.36 no.4
• /
• pp.437-445
• /
• 2014

A time-series sediment trap was operated at a water depth of 4950 m from July 2003 to May 2004 at KOMO station ($10^{\circ}30^{\prime}N$, $131^{\circ}20^{\prime}W$) in the northeastern equatorial Pacific, with the aim of understanding the temporal variation of planktonic foraminifera assemblages in response to the seasonal shift of Inter-Tropical Convergence Zone (ITCZ). A total of 22130 planktonic foraminifera specimens belonging to 30 species and 11 genera were identified, which shows a distinct seasonal variation with high values (125~288 specimens $m^{-2}day^{-1}$) in the winter to spring (December-May) and low values (16~23 specimens $m^{-2}day^{-1}$) in the fall (September-November). In addition, seasonal ecological differences of foraminifera assemblages are distinctly recognizable: omnivorous foraminifera occurred predominantly during the summer season, whereas herbivorous ones were dominant during the winter season. Such seasonal variations correspond to the seasonal shift of the ITCZ. Enhanced occurrence of herbivorous species during the winter-spring season seems a result of surface water mixing generated by the southward shift of the ITCZ. The increase in omnivorous species during the summer season may be due to the northward movement of the ITCZ caused by weakened wind speed, resulting in the intensification of water column stratification and nutrient-poor environment. A significant reduction of planktonic foraminifera specimens during the fall is attributed to heavy precipitation and reduction in light intensity.