• 한국정밀공학회지
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• 제7권4호
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• pp.117-129
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• 1990

The mixed mode surface crack in finite-width plate subjected to uniform shearing has been analyzed in 3-D problem by using boundary element method. The calculations were carried out for the surface crack angles (${\alpha}$) of $0^{\circ}, 15^{\circ}, 30^{\circ}, 45^{\circ}, 60^{\circ}, and 75^{\circ}, $ and for the aspect ratio(a/c) of 0.2, 0.4, 0.6 and 1.0 to get stress intensity factors at the boundary points of the surface crack. For the aspect ratio of 1.0 and the surface crack angles, finite element method was used to check the results in this in this study. Comparison of the results from both method showed good agreement.

• 한국환경과학회지
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• 제4권5호
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• pp.141-141
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• 1995

The waste biomass of Sacchromyces uvarum, used in fermentation industries to produce ethanol, were studied for their ability to absorb various heavy metal ions. Heavy metal ions studied in this research were Cd, Co, Cr, Cu, Ni and Pb. The order of the sorption capacity was Pb>Cu>Co=Cr=Cd>Ni. The living Sacchromyces uvarum exhibited higher metal-uptake capacity than the dead Sacchromyces uvarum. After we compare the uptake capacity of the Sacchromyces uvarum for individual metal ions with for a mixture of them, the following was observed: in the mixed heavy metal solution the uptake capacity was decreased than the one heavy metal solution. The selective uptake was observed when all . the heavy metal ions were dissolved in a mixed solution. The adsorption isotherm modelling was decribed with the Langmuir and Freundlich model. The results were in good agreement with the Langmuir model.

• 한국환경과학회지
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• 제4권5호
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• pp.527-534
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• 1995

The waste biomass of Sacchromyces uvarum, used in fermentation industries to produce ethanol, were studied for their ability to absorb various heavy metal ions. Heavy metal ions studied in this research were Cd, Co, Cr, Cu, Ni and Pb. The order of the sorption capacity was Pb>Cu>Co=Cr=Cd>Ni. The living Sacchromyces uvarum exhibited higher metal-uptake capacity than the dead Sacchromyces uvarum. After we compare the uptake capacity of the Sacchromyces uvarum for individual metal ions with for a mixture of them, the following was observed: in the mixed heavy metal solution the uptake capacity was decreased than the one heavy metal solution. The selective uptake was observed when all . the heavy metal ions were dissolved in a mixed solution. The adsorption isotherm modelling was decribed with the Langmuir and Freundlich model. The results were in good agreement with the Langmuir model.

• Bulletin of the Korean Chemical Society
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• 제23권8호
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• pp.1111-1115
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• 2002

The photoluminescence of calixarene crystals has been studied as functions of temperature, time, and concentration. The vibronic bands shift to longer wavelength and become significantly sharper as temperature decreases. The experimental results r eveal that the structural transformation occur during the annealing process. Time-resolved spectra of calixarene at 12 K are monitored. Spectral features, which demonstrate characteristic of energy transfer processes, are not observed. The depopulation of excited state density is mainly controlled by unimolecular decay process dominating other decay processes. The lifetime was found to be 2.6 $\pm$ 0.1 ns. For the case of calixarene mixed with naphthalene, the fluorescence spectrum shows that the band centered at 340 nm lies 2840 $cm^{-1}$ below the relatively broad 310 nm band found for calixarene crystals. The spectra also exhibit that the emission intensity increases with increasing calixarene concentration. The results are evident that the calixarene emission is quenched by the naphthalene. Phosphorescence of calixarene mixed with naphthalene crystals is observed to determine whether the emission is due to naphthalene. The phosphorescence peaks were compared with the ground-state vibrational frequencies of naphthalene and found to be in good agreement. The results indicate that inter-molecular energy transfer occurs between calixarene and naphthalene.

• Steel and Composite Structures
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• 제27권6호
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• pp.789-801
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• 2018

A weak-form formulation of finite annular prism methods (FAPM) based on Reissner's mixed variational theorem (RMVT), is developed for the quasi three-dimensional (3D) static analysis of two-directional functionally graded (FG) circular plates with various boundary conditions and under mechanical loads. The material properties of the circular plate are assumed to obey either a two-directional power-law distribution of the volume fractions of the constituents through the radial-thickness surface or an exponential function distribution varying doubly exponentially through it. These FAPM solutions of the loaded FG circular plates with both simply-supported and clamped edges are in excellent agreement with the solutions obtained using the 3D analytical approach and two-dimensional advanced plate theories available in the literature.

• Journal of applied mathematics & informatics
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• 제26권1_2호
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• pp.161-176
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• 2008

The effect of variable viscosity on MHD mixed convection Hiemenz flow over a thermally stratified porous wedge plate has been studied in the presence of suction or injection. The wall of the wedge is embedded in a uniform Darcian porous medium in order to allow for possible fluid wall suction or injection and has a power-law variation of the wall temperature. An approximate numerical solution for the steady laminar boundary-layer flow over a wall of the wedge in the presence of thermal diffusion has been obtained by solving the governing equations using numerical technique. The fluid is assumed to be viscous and incompressible. Numerical calculations are carried out for different values of dimensionless parameters and an analysis of the results obtained shows that the flow field is influenced appreciably by the magnetic effect, variable viscosity, thermal stratification and suction / injection at wall surface. Effects of these major parameters on the transport behaviors are investigated methodically and typical results are illustrated to reveal the tendency of the solutions. Comparisons with previously published works are performed and excellent agreement between the results is obtained.

• 한국도로학회논문집
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• 제19권4호
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• pp.37-44
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• 2017

PURPOSES : Conductive and convective heat transfer simulations for an asphalt mixture were made by using discrete element method (DEM) and similarity principle. METHODS : In this research, virtual specimens composed of discrete element method particles were generated according to four different predetermined particle size distribution curves. Temperature variations of the four different particles for a given condition were estimated and were compared with measurements and analytical solutions. RESULTS : The virtual specimen with mixed particles and with the smallest particle show very good agreement with laboratory test results and analytical solutions. As particle size decreases, better heat transfer simulation can be performed due to smaller void ratio and more contact points and areas. In addition, by utilizing the similarity principle of thermal properties and corresponding time unit, analytical time can be drastically reduced. CONCLUSIONS : It is concluded that the DEM asphalt mixture specimens with similarity principle could be used to predict the temperature variation for a given condition. It is observed that the void ratio has critical effect on prediction of temperature variation. Comparing the prediction for a 4 mm particle specimen with a mixed particle specimen, it is also concluded that predicting the mixed particle specimen temperature is much more efficient considering the number of particles that are directly associated with computational time in DEM analysis.

• KSBB Journal
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• 제9권1호
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• pp.40-47
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• 1994

Fructosyltransferase와 glucose oxidase의 혼합효소계를 이용한 고순도 fructo-oligosaccharides 생산반응에서의 수학적 모델을 제안하고 실험적으로 검증한 결과 실험치와 모델 값이 서로 잘 일치하였다. 혼합 효소계에서 두 효소의 kinetic parameters를 구한 결과, fructosyltransferase 단일 효소계에서의 값들에 비해 $K_m$ 값들은 감소하였고, $K_m,\;V_{max}$값들은 증가하였다. 혼합 효소계의 반응메카니즘은 전체적으로 Michaelis-Menten kinetics로 표현할 수 있었고, 제안된 모델을 이용하여 고순도 fructo-oligosaccharides 생산에 이상적인 설탕농도를 예측할 수 있었다.

• 한국유체기계학회 논문집
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• 제13권5호
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• pp.11-16
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• 2010

The development of lifting pumps that lift minerals to a mining vessel are one of the vital parts of the commercial mining process. The purpose of this study is to investigate internal flow and its effect on the performance of a mixed flow pump in order to improve the pump's performance. Numerical analysis was performed by commercial code of ANSYS CFX-11 based on flow rate and length of flexible hose. The rated rotational speed of the impeller is 1750rpm. For taking into account the turbulence, k-$\omega$ SST model was selected to guarantee more accurate prediction of flow separation. The simulated results are in good agreement with the experimental results and showed that its efficiency and the head of the pump are related mainly to the flow rate and the length of flexible hose. A lesser flow rate caused more secondary flow through the guide vane passage. The length of flexible hose and flow rate exert much more influence on the pump's performance than the shape of the flexible hose.

• Journal of the Optical Society of Korea
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• 제14권3호
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• pp.178-184
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• 2010

We present linear particle depolarization ratios (LPDRs) retrieved from measurements with an AERONET Sun photometer at the Gwangju Institute of Science and Technology (GIST), Korea ($35.10^{/circ}N$, $126.53^{\circ}E$) between 19 October and 3 November 2009. The Sun photometer data were classified into three categories according to ${\AA}$ngstr$\ddot{o}$ exponent and size distribution: 1) pure Asian dust (19 October 2009), 2) Asian dust mixed with urban pollution observed in the period from 20-26 October 2009, and 3) clean conditions (3 November). We show that the LPDRs can be used to distinguish among Asian dust, mixed aerosol, and non-Asian dust in the atmosphere. The mean LPDR of the pure Asian dust case is 23 %. Mean LPDRs are 13 % for the mixed case. The lowest mean LPDR is 6 % in the clean case. We compare our results to vertically resolved LPDRs (at 532 nm) measured by a Raman LIDAR system at the same site. In most cases, we find good agreement between LPDRs derived with Sun photometer and measured by LIDAR.