• Journal of Korea Soil Environment Society
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• v.5 no.1
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• pp.3-12
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• 2000

The multi-region model, to describe preferential flow, is an equation representing solute transport in soils by dividing soil into numerous pore groups and using the hydraulic properties of the soil. As the model partial differential equation (PDE) is solved numerically with finite difference methods. a modified equivalent partial differential equation(MEPDE) of the partial differential equation of the multi-region model is derived to analyze the accuracy and consistency of the solution of the model PDE and the Von Neumann method is used to analyze the stability of the finite difference scheme. The evaluation obtained from the MEPDE indicated that the finite difference scheme was found to be consistent with the model PDE and had the second order accuracy The stability analysis is performed to analyze the model PDE with the amplification ratio and the phase lag using the Von Neumann method. The amplification ratio of the finite difference scheme gave non-dissipative results with various Peclet numbers and yielded the most high values as the Peclet number was one. The phase lag showed that the frequency component of the finite difference scheme lagged the true solution. From the result of the stability analysis for the model PDE, it is analyzed that the model domain should be discretized in the range of Pe < 1.0 and Cr < 2.0 to obtain the more accurate solution.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.375-378
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• 2002

Hydrogen producing bacterium, strain Ye13-6 was isolated from the sludge of the factory areas in Gunpo through the acclimation in basal salt medium(BSM) supplemented with 10g/ ${\ell}$ of sucrose. Isolated strain Ye13-6 was a facultative anaerobe which could grow in both aerobic and anaerobic environments. Effects of the concentrations of glucose and sucrose on the hydrogen production rate and the hydrogen production yield were investigated. When glucose in the range of 1${\sim}$12g/ ${\ell}$ was supplemented to the BSM, strain Ye13-6 could grow without lag phase. An increased glucose concentration increased the specific hydrogen production rate linearly to 60mmol-$H_2$ ${\cdot}$ mg-$DCW^{-1}$ ${\cdot}$ $h^{-1}$. The hydrogen production yield was maintained over a range from 2.6 to 3.1mol-$H_2$ ${\cdot}$ mol-$glucose^{-1}$. When sucrose in the range of 1${\sim}$12g/ ${\ell}$ was supplemented to the BSM, strain Ye13-6 could grow after ten hours. An increased sucrose concentration increased the specific hydrogen production rate and the hydrogen production yield to 163mmol-$H_2$ ${\cdot}$ mg-$DCW^{-1}$ ${\cdot}$ $h^{-1}$ and to 4.5mol-$H_2$ ${\cdot}$ mol-$sucrose^{-1}$, respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.8 no.1
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• pp.85-99
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• 1984

The stability of the two-phase flow in a heated channel is of great importance in the design and operation of the boilers and light water nuclear reactors, because it can cause flow oscillations and lead to a violation of thermal limits with resultant overheating of the channels and cladding. This paper presents a systematic evaluation to the variation effects of the basic four (4) dimensionless parameters in a homogeneous equilibrium model. The flow stability is examined on the ground of static characteristic curves. The complicated transfer function of flow dynamics which gives consideration to the transport lag of density wave is derived, and the transient flow stability is analysed by applying the Nyquist stability criterion in control engineering. The analysis results summed up as follows 1. The coolant flow becomes stable in large friction number and specific flow, while it is unstabale in small friction number and flow. 2. Large phase-change number and Froude number destabilize the two-phase flow, but small numbers stabilize it. The effect to variation of phase-change number is more dominant compared with Froude number. 3. The dynamic analysis is required to hold the sufficient safety of heated channels since only static results does not keep it. The special attention could be payed in the design and operation of heat engines, because the unstaable region exists within the stable boundary at small and middle phase-change number and Froude number.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.60-65
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• 1994

In this study, the dynamic characteristics of a turbine-meter-type flowmeter is investigated by making use of the remote instantaneous flow rate measurement method (RIFM). The results of the frequency response test indicated that the gain of the flow rate of the turbine-meter-type flowmeter relative to the flow rate of the RIFM was nearly unity up to 40Hz and the phase lag of the flow rate became 90 degrees at 70Hz.

• The Korean Journal of Food And Nutrition
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• v.1 no.2
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• pp.64-67
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• 1988

Cadmium resistant cocobacillus B-17 from soil was tolerated up to 1600ug/ml of cadmium at agar plate and the strain B-17 was able to grow at 600ug/ml of cadmium at liquid medium after the lag phase being prolonged with lengthening culture time. Optimal pH of the strain was shown at pH7.0. The elimination frequency of cadmium resistance by 10ug/ml of acriflavin was 28%, and by 20ug/ml of ethidium bromide was 47%, respectively.

• Journal of Sensor Science and Technology
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• v.19 no.3
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• pp.191-196
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• 2010

In this paper, modeling of the non-ideal frequency response, especially "notch-and-spike" magnitude phenomenon and phase lag distortion, are discussed. To characterize the non-ideal frequency response, a new electro-mechanical simulation model based on SPICE is proposed using the driving loop of the capacitive vibratory gyroscope. The parasitic components of the driving loop are found to be the major factors of non-ideal frequency response, and it is verified with the measurement results.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.837-840
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• 1995

Finite element analysis using two dimensional magnetic permeabillity tensor that can represents phase lag between magnetic field intensity and flux density under rotational flux is examined. Considered problem is confined to two dimensional magnetostatic case. And we applied proposed method to calculate the core loss of the test model and compare the result with that of experiment.

• Microbiology and Biotechnology Letters
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• v.10 no.3
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• pp.227-232
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• 1982

The methods determining the growth rate of mold on beans were investigated in order to compare the growth of Aspergillus oryzae on lupinseed to that on soybean. The growth of A. oryzae on cooked whole or paste form of bean substrates was evaluated by the measurements of colony diameter and hyphae length of the mold. The mold showed characteristic lag times to form the colony on different types of substrate. The growth of colony diameter was coincided with the increase in $\alpha$-amino nitrogen content of the substrate when the moisture level of the substrates was similar each other. The colony diameter and the cultivation time after the lag period showed a straight line relationship, from which the growth rate was estimated. in general, lupinseed paste allowed faster growth of A. oryzae than soybean paste at the initial growth phase. The lag time to form the colony was 24.0 hrs on lupinseed paste and 44.4 hrs on soybean paste. The growth rate after colony formation was, however, 7.05 mm/day for lupinseed paste and 8.83mm/day for soybean paste, which indicated that the growth rate after the lag period was faster on soybean compared to lupinseed. The sporulation time of the mold was related to the lag time for the colony formation. The measurement of hyphae length on whole beans could be used as a simple and rapid method of estimating the growth property of mold on different substrates.11 showed that the growth of A. oryzae was partly hindered by the thick hull of the lupinseed.

• Journal of Environmental Science International
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• v.3 no.1
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• pp.65-76
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• 1994

The regiospecific potential for the reductive dechlorination of 2-, 3-, 4-, 2, 3-, 2, 4-, and 3, 4-chlorophenols (CPs) was studied in mono- and di-CP(DCP) adapted sediment slurries(10% solids). Freshwater sediments adapted to transform 2-CP dechlorinated all tested mono- and di-CPs except 4-CP without a lag period. Adaptation to 2-CP, thus, enhanced the onset of dechlorination of 3-CP and all ortho-substituted CPs tested. Sediment adapted to transform 3-CP dechlorinated all test CPs, except 4-CP and 2, 4-DCP, without a lag period. Sediment adapted to individual DCPs (2, 3-, 2, 4-, and 3, 4-DCP_ exhibited dechlorination(no lag phase) of 2-CP, 2, 3-, 2, 4-, and 3, 4-CDP. Interestingly, meta-cleavage of 3, 4-DCP in all tested adapted sediment occurred, while para-cleavage occurred in 3, 4-DCP adapted sediment. Sediment adapted to dechlorinate ortho and meta-chlorines exhibited a preference for meta following ortho-cleavage, but not for para-cleavage, while the preference for reductive dechlorination was ortho>meta>para for mono-CPs and ortho>para>meta for DCPs in unadapted freshwater anoxic sediments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1167-1174
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• 2008

The measurement of two-dimensional magnetic properties of electrical steel sheet using single sheet tester (SST) requires to control the B-waveform as sinusoidal. The SST electric circuit, in general, has inductance, and this makes the phase lag in electric current. For this reason, the induced voltages of H- or B-coil may have phase difference from the exciting voltage. In this paper, a new algorithm is developed to compensate the phase difference and makes the B-waveform control efficient. The developed algorithm experimentally calculates the phase difference based on the measured waveform of the induced voltage for the magnetic field intensity along transverse direction. By using the proposed algorithm, the two-dimensional magnetic properties of grain-orientated electrical steel sheet (30PG110) is measured up to 2T. By comparing the measured B- and H-waveforms, the effectiveness of the proposed algorithm is proven.