• Economic and Environmental Geology
• /
• v.41 no.6
• /
• pp.731-746
• /
• 2008

Most multiphase flow simulators following fractional flow approach assume incompressibility of fluid and matrix or consider only two phase flow (water and air, water and NAPL). However, in this study, mathematical governing equations were developed for fully compressible three-phase flow using fractional flow based approach. Also, fully compressible multiphase flow simulator (CMPS) considering compressibilities of matrix and fluid was developed using the mathematical governing equations. In order to verify CMPS, the CMPS were compared with analytical solution and the existing multiphase flow simulator, MPS, which had been developed for simulating incompressible multiphase flow (Suk and Yeh 2007; Suk and Yeh 2008). According to the results, solutions of CMPS and MPS and analytical solutions are well matched each other. Thus, it is found that CMPS has the capability of simulating compressible three phase flow phenomena assuming compressibilities of fluids and matrix.

• Korean Journal of Veterinary Research
• /
• v.37 no.1
• /
• pp.195-202
• /
• 1997

A method for the isolation by matrix solid phase dispersion method and liquid chromatographic determination of enrofloxacin and ciprofloxacin in pork muscle tissue is presented. Blank or enrofloxacin and ciprofloxacin spiked samples(0.5g) containing 0.05g oxalic acid were blended with $C_{18}$(octadecylsilyl derivatized silica) packing material. After homogenization, $C_{18}$/muscle tissue matrix was transferred to glass column made from 10ml glass syringe and filter paper, and compressed to 4~4.5ml volume. A column was washed with 8ml of hexane and dried under vacuum. Interfering materials were removed by ethylacetate 8ml and dried, following which enrofloxacin and ciprofloxacin were eluted with 8ml of methanal under gravity. The eluate containing enrofloxacin and ciprofloxacin wase free from interfering compound when analysed by HPLC with UV detection at 278nm. Enrofloxacin and ciprofloxacin showed linear response with UV detector at the range of $0.05{\sim}1.0{\mu}g/ml$ and eluted within 5ml elution volume of methanol from the matrix. Fortified sample containing 0.05g oxalic acid represented more good recoveries than that of control sample. Average percentages of enrofloxacin and ciprofloxacin were $93.30{\pm}4.56%$ and $91.84{\pm}4.17%$, respectively, for the concentration range(0.05, 0.1, 0.25, 0.5 and $0.75{\mu}g/g$). The interassay variability of enrofloxacin was $6.02{\pm}5.33%$ with an intra-assay variability of 4.89% and $6.75{\pm}2.68%$ with 4.54% for ciprofloxacin. Detection limit of enrofloxacin and ciprofloxacin was $0.030{\mu}g/g$ in the spiked sample.

• Korean Journal of Optics and Photonics
• /
• v.33 no.6
• /
• pp.252-259
• /
• 2022

We have conducted a study to control the light-intensity distribution at the output end of a multimode optical fiber via estimating the transmission matrix. A circularly arranged Hadamard eigenmode phase distribution was implemented using a spatial light modulator, and the transmission matrix of a multimode optical fiber was experimentally obtained using a four-phase method. Based on the derived transmission matrix, the spatial phase distribution of light incident upon the optical fiber was adjusted via the spatial light modulator in advance, to focus the light at a desired position at the optical fiber output. The light could be focused with an intensity up to 359.6 times as high as that of the surrounding background signal at a specific position of the multimode fiber's output end, and the intensity of the focused beam was on average 104.6 times as large as that of the background signal, across the area of the multimode fiber's core.

• Journal of Technologic Dentistry
• /
• v.28 no.1
• /
• pp.27-41
• /
• 2006

The physical property and phase transformation in a commercial dental casting high gold alloy was investigated as a function of ageing temperature and time using microvickers hardness tester, X-ray diffraction, optical and electron microscopy and EPMA analyser. 1. With increasing ageing time, the hardness of solution-treated gold alloys increased slowly at the initial stage of ageing treatment at an ageing temperature of $300{\sim}400^{\circ}C$, and it reached a maximum value of hardness at the medium stage. Finally, it decreased gradually during further ageing. The maximum value of hardness at was similar with that of the conventional materials and suitable for using as the crown & bridge. 2. During isothermal ageing at a temperature range of $300{\sim}400^{\circ}C$, three phases consisting of the Au-rich ${\alpha}_1$phase with a face-centered cubic structure, the Pt3Zn ${\alpha}_2$phase with an ordered AuCu3(L12) type(f.c.c.) and the Pt-rich ${\alpha}_3$phase with face-centered cubic structure in solution-treated gold alloys were transformed into different three phases consisting of the ${\alpha}_1$phase, the ${\alpha}_3$phase and the PtZn $\beta$phase with an ordered AuCu I(L10) type. 3. The hardening of gold alloys was attributed to the lattice strains of the matrix resulting from the transformation of the ${\alpha}_2$phase to the $\beta$phase. 4. The softening of gold alloys during over-ageing was attributed to the coarsening of the nodules consisting of the $\beta$phase and ${\alpha}_1$matrix.

• Journal of Biosystems Engineering
• /
• v.27 no.6
• /
• pp.529-536
• /
• 2002

The performance of stilting engine, in particular, its energy conversion efficiencies are critically influenced by the regenerator characteristics. The regenerator characteristics are influenced by effectiveness, void fraction. heat transfer loss and fluid friction loss in the regenerator matrix. These factors were influenced by the surface geometry and material properties of the regenerator matrix. The regenerator design goals arc good heat transfer and low pressure drop of working Bas across the regenerator. Various data for designing a wire screen matrix have been given by Kays and London(1984). The mesh number of their experiment. however, was confined below the No. 60. which seems rather small for the Stirling engine applications. In this paper. in order to provide a basic data for the design of regenerator matrix, characteristics of heat transfer and flow friction loss were investigated by a packed mettled of matrix in oscillating flow as the same condition of operation in a Stirling engine. Seven kinds of sing1e wire screen meshes were used as the regenerator matrices. The results are summarized as follows; 1. While the working fluid flew slowly in the regenerator. the temperature difference was great at the both hot-blow(the working fluid flows from healer to cooler) and cold-blow(the working fluid flows from cooler to healer). On the other hand. while the working fluid flew fast. the temperature difference was not distinguished. 2. The No.150 wire screen used as the regenerator matrix showed excellent performance than tile others. 3. Phase angle variation and filling rate affected heat transfer or regenerator matrices. 4. Temperature difference between the inlet and outlet of the regenerator is very hish in degree of 120 phase angle.

• Journal of Power Electronics
• /
• v.12 no.1
• /
• pp.24-32
• /
• 2012

Direct duty-ratio PWM schemes for continuous fault tolerant operation of matrix converter-fed motor drives are presented. The proposed method features simple modular modulation structure based on per output phase concept, which requires no additional modification on the normal modulation schemes for fault-tolerant applications. Realizations of fault-tolerant strategy applied to different system configurations are also treated to enhance the system flexibility. The proposed method can be effectively applied to treat the motor open phase fault and converter switching device failure. Simulation and experimental results show the feasibility and validation of the proposed strategies.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.3
• /
• pp.334-338
• /
• 2009

In this paper, We report the miniaturization of superconducting microwave power dividers based on lumped element equivalent circuits. To do this, we analyzed a conventional branch-type power divider by using an ABCD matrix under even and odd mode excitation. Then, we calculated each lumped element impedance throughout this analysis of a transmission line matrix. Also we simulated our equivalent circuits made of lumped elements by using a full wave analysis, em Sonnet. Our deign of microwave power divider based on simulated results was fabricated on high-$T_c$ superconducting thin films deposited on MgO substrate. Experimental results were reported in terms of bandwidth, center frequency, and phase difference between $S_{21}$ and $S_{31}$. We confirm that our design will be useful in the future microwave power systum.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
• /
• 2004.10a
• /
• pp.407-411
• /
• 2004

Ohmic heating occurs when an electric current is passes through food, resulting in a temperature rise in the product due to the conversion of the electric energy into heat. The time spent in the thawing is critical for product sterility and quality. The objective of this study is to conduct numerical modelling between the effect of ohmic thawing intensity on PTT(phase transition time) at constant concentration and the effect of matrix concentrations on PTT at constant voltage condition. the stronger ohmic thawing intensity resulted in decreasing the PTT. High ohmic intensity causes short PTT. And the higher gelatin concentration, the faster increment of PTT. A numerical modeling was executed to predict the PTT influenced by the power intensity using exponential regression and the PTT influenced by gelatin concentration using logarithmic regression. Therefore, from this numerical model of gelatin matrix, it is possible to estimate exact values extensively.

• Proceedings of the KIPE Conference
• /
• 2003.07b
• /
• pp.635-638
• /
• 2003

In the paper, a three-phase-in three-phase-out Matrix Converter(MC) for the PMSM Is simulated by the PSIM simulator. A lighter L-C filters are installed at the input side of the Converter to remove the current harmonics around the switching frequency. In modelling the Matrix Converter, the PSIM is the powerful tool that the basic researches can be quickly performed within the given periods, because the simulation calculation by PSIM is very fast, compared to other simulators such as Matlab, Saber, and Pspice.

• Journal of the Korean Ceramic Society
• /
• v.34 no.10
• /
• pp.1092-1098
• /
• 1997

Electrical discharge machining (EDM) was attempted on a ceramic matrix composite containing non-conductive alumina as a matrix and conductive titania as a second phase, and was found successful. As the current or duty factor increased, the material removal rate (MRR) increased and the surface roughness also increased. The EDMed surface was covered with a number of craters of a circular shape having 100-200 microns of diameter. The melting and evaporation was suggested for the EDM mechanism. The bending strength decreased 44% after EDM, but the Weibull modulus increased more than twice. Combination of EDM and barre이 polishing resulted in the maintenance of the bending strength level. Temperature distribution near a spark in the sample was computer-simulated by use of finite element method, and was found to have similar shape to the one which the observed craters have.