• Proceedings of the Korean Society of Organic Agriculture Conference
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• 2004.12a
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• pp.1-16
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• 2004

This study was conducted to investigate effects of different ratios of sawdust to poultry manure as an earthworm feed on the change of physico-chemical characteristics and earthworm viability during composting, and further to provide the basic information for an efficient vermicomposting using the manure of livestock. Experimental earthworm used in this study was Eisenia foetida and the ratio of sawdust and poultry was determined to 100:0(A), 80:20(B), 70:30(C), 60:40(D) and 50:50(E) on the basis of volume. The results are summarized as follows. Earthworm appeared after 6 wk of aging period, and it was possible for the earthworm to survive in treatments of C. D and E including 30 $^{\sim}$ 50% of sawdust. C/N ratio was significantly higher (P<0.05) in treatments of sawdust mixture (B, C, D, and E) than poultry manure alone (A treatment).Appropriate C/N ratio for earthworm survival was the range of 16.9 to20.7. During period of aging, pH value and electrolyticconductivity (EC) were the highest in the treatment of poultry manure alone. However, as the inclusion of sawdust was increased, pH showed decreasing tendency. Appropriate pH and EC for earthworm survival were 7.69 to 7.79, and 2.77 to 2.87mS/cm, respectively. The results from this study indicated that the mixing of poultry manure with sawdust more improved physico-chemical environment for earthworm growth in comparison with poultry manure alone, and sawdust showed the sufficient possibilityas a bulking agent for an efficient vermicomposting of poultry manure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.9A
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• pp.2153-2164
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• 1998

This paper has presented the parameters for the coexistence between two systems in macro/microcell ovelaid W-CDMA WLL (wideband CDMA wireless local loop) and has calculated the capacity of forward/reverse link in microcell. To produce the capacity for analyzing system interference effects, we have shown tables and graphs with the parameters sucyh as RF channel bandwidth of WLL(W), the transmission rate of service message(R), the required signal power to noise power ratio( $E_{b/}$ $N_{0}$) for achieving accepatable error rate, te user number ( $N_{W1}$, $N_{W2}$) of the neighboring system, the signal power to interference power ratio(.GAMMA.$_{C1B}$, .GAMMA.$_{C2B}$) of the neighboring system, the normalized distance(d) between microcell and macrocell base-station, and microcell to macrocell radius ratio ( $R_{d}$). From the results, we have convinced that the capacity of microcell diminishes as increasing the user number ( $N_{W2}$) in macrocell, increasing the microcell radius, and decreasing the normalized distance(d) between microcell and macrocell base-station. Especially, we have known that when $R_{d}$=0.1, $N_{W2}$ must be below 24 at .GAMMA.$_{C2B}$ = 0 dB and below 8 at .GAMMA.$_{C2B}$ = 4 dB for the acceptable capacity raito to be over 80%. Therfore, this paper is usefult to design microcell W-CDMA WLL for accommodating more user number under the interference effects of macrocell W-CDMA WLL and is expected to be reference in power control if base-station.ation.ion.ation.ation.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.223-226
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• 2005

In order to acquire 3 components data which has the good signal to noise ratio with only one shot, 3-C geophones were used, As a result, the vertical component showed the distinct first arrival of P-wave, and the horizontal component was improved the signal to noise ratio of S-wave, while was attenuated P-wave. The 2-D Poisson's ratio section was computed from P- and S-wave cell velocities included velocity tomograms of the P- and S-waves. The Poisson's ratio values were computed in the range of $0.2{\~}0.3$. With one shot, we can obtain 2-D distribution of dynamic Poisson's ratio as well as velocity tomograms of P- and S-waves.

• Journal of Ocean Engineering and Technology
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• v.14 no.3
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• pp.78-83
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• 2000

In this study, CT specimens were prepared from AST SA516 Gr. 70 which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at 25$^{\circ}C $, -60$^{\circ}C $, -80$^{\circ}C $ and -100$^{\circ}C $ and in the range of stress ratio of 0.05, 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ${\delta} K_{th}$ in the early stage of fatigue crack growth (Region I) and stress intensity factor range $\delta $K in the stable of fatigue crack growth (Region II) were increased in proportion to descending temperature. It was assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN -$\delta $K in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It was assumed that the fatigue crack growth rate da/dN is rapid in proportion to descending temperature in Region II and the cryogenic-brittleness greatly affect a material with decreasing temperature.

• Journal of IKEEE
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• v.24 no.1
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• pp.186-193
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• 2020

In this paper, we propose a multi-threading system to support reconfigurable hardware accelerators on Zynq SoC. We implement high-performance JPEG decoder with reconfigurable 2D IDCT hardware accelerators to achieve maximum performance available on the platform. In this system, up to four reconfigurable hardware accelerators synchronized with SW threads can be dynamically reconfigured to provide adaptive computing capabilities according to the given image resolution and the compression ratio. JPEG decoding is operated using images with resolutions 480p, 720p, 1080p at the compression ratio of 7:1-109:1. We show that significant performance improvements are achieved as the image resolution or the compression ratio increase. For 1080p resolution, the performance improvement is up to 79.11 times with throughput speed of 99 fps at the compression ratio 17:1.

• Wind and Structures
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• v.38 no.1
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• pp.59-74
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• 2024

Large Eddy Simulation (LES) is used to explore the influence of vibration frequency and amplitude on the aerodynamic performance of a rectangular cylinder with an aspect ratio of B/D=5 (B: breadth; D: depth of cylinder) at a Reynolds number of 22,000 near resonance frequency. In smooth flow conditions, the research employs a sequence of three-dimensional simulations under forced vibration with diverse frequency ratios f_e / f_o = 0.8-1.2 (f_e : oscillation frequency; f_o : Strouhal frequency when the rectangular cylinder is stationary ) and oscillation amplitudes A_h/D = 0.05 - 0.3. The individual influences of f_e / f_o and A_h/D on the characteristics of integrated and distributed aerodynamic forces are the focal points of discussion. For the integrated aerodynamic force, particular emphasis is placed on the analysis of the dependence of velocity-proportional component C₁ and displacement-proportional component C₂ of unsteady aerodynamic force on amplitude and frequency ratio. Near the resonance frequency, the dependencies of C₁ and C₂ on amplitude are stronger than that of frequency ratio. For the distributed aerodynamic force, the increase in frequency and amplitude promotes the position of the main vortex core and reattachment to the leading edge in the streamwise direction. In the spanwise direction, vibration enhances the spanwise correlation of aerodynamic force to weaken the three-dimensional effect of the flow field, and a lower frequency ratio and larger amplitude amplify this effect.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.219-226
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• 2003

The fatigue crack growth behavior of the SA516/60 steel used for pressure vessels was examined experimentally at room temperatures $25^{\circ}C$,$-30^{\circ}C$, $-60^{\circ}C$, $-80^{\circ}C$, $-100^{\circ}C$ and $-120^{\circ}C$ with stress ratio of R=0.05, 0.1 and 0.3. fatigue crack propagation rate da/dN related with stress intensity factor range $\Delta$K was influenced by stress ratio in stable than fatigue crack growth (Region II) with an increase in $\Delta$K. The resistance of fatigue crack growth at low temperature is higher compared with that at room temperature, which is attributed to the extent of plasticity-induced by compressive residual stress according to the cyclic loads. Fractographic examinations reveal that the differences of the fatigue crack growth characteristics between room and low temperatures are explained mainly by the crack closure and the strengthening due to the plasticity near the crack tip and roughness of the crack faces induced.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.359-365
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• 2002

The fatigue crack growth behavior of the SA516/60 steel which is used for pressure vessels was examined experimentally at room temperature $25^{\circ}C,\;-30^{\circ}C,\;-60^{\circ}C,\;-80^{\circ}C,\;-100^{\circ}C$ and $-120^{\circ}C$ with stress ratio of R=0.05, 0.1 and 0.3. Fatigue crack propagation rate da/dN related with stress intensity factor range ${\Delta}K$ was influenced by stress ratio in stable of fatigue crack growth (Region II) with an increase in ${\Delta}K$. The resistance of fatigue crack growth at low temperature is higher compared with that at room temperature, which is attributed to tile extent of plasticity-induced by compressive residual stress according to the cyclic loads. Fractographic examinations reveal that the differences of the fatigue crack growth characteristics between room and low temperatures are mainly explained by the crack closure and the strengthening due to the plasticity induced and roughness induced.

• Journal of Industrial Technology
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• v.18
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• pp.439-442
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• 1998

In this paper, we firstly suggested C&D (Common mode and Differential mode) model for the representation of a stereophonic signal. Then a measure of stereophonic channel separability is defined as the ratio of differential mode energy to total energy in frequency domain. After that, a new channel separability enhancement scheme is proposed by the control of common mode rejection. Finally, some experimental results are presented in order to verify our scheme.

• Journal of the Korean Chemical Society
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• v.40 no.9
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• pp.630-634
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• 1996

In order to explore a substrate specificity for cabbage phospholipase D, we examined the PLD reactivity toward the phosphatidylcholines with different chain length of acyl groups. The selected acyl chains were the saturated fatty acid of $C_8:0,\;C_{12}:0,\;C_{16}:0,\;C_{20}:0$. The reactivity of these phospholipids were dependent largely on the ratio of PC : SDS. The PC : SDS ratio showing the optimal PLD activity were found to be 1:1.4, 1:2.2, 1:2.5, and 1:3.6 respectively as the increase of the acyl chain length. Likewise the optimum temperature for the maximal PLD activity were altered markedly to 25$^{\circ}C$, 30$^{\circ}C$, 35$^{\circ}C$, 45$^{\circ}C$ when the length of acyl chains increased. On the contrary the pH and concentration of $Ca^{2+}$ necessary for the optimum PLD activity were not altered significantly. The kinetic parameter $V_{max}$ for short acyl chain substrate was greater than the values for the longer acyl chain, which indicates the fastest rate of hydrolysis. By the same token, the reactivity of longer chain substrate became slower for the hydrolysis activity.