• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.387-394
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• 1995

A simple method for determining the absorption coefficient of oxyhemoglobin and deoxyhemoglobin in human blood is proposed as an application of the complex propagation constant of a guided wave in a thin-film optical waveguide. A serial multichannel sample chamber is constructed on the waveguide to vary the interaction length between the evanescent field and the sample, and the dependence of the sensor response on the interaction length is investigated for the various concentration of two hemoglobins. The sensor response is linearly proportional to the interaction length and the concentration of two hemoglobins. The attenuation constant due to the evanescent field absorption between the samples is experimentally obtained with the designed sensor, and then the absorption coefficient is determined by the proposed method. The absorption coefficients determined by the proposed method fairly well coincided with those obtained by the conventional transmission measurement.

• The Journal of Industrial Distribution & Business
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• v.10 no.2
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• pp.25-37
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• 2019

Purpose - The goal of this study is to analyze the differences in education performances between students of the government's financial support program and those who do not receive support at a local university in Korea. Research design, data, and methodology - The questionnaire used was NASEL. NASEL is considered a highly suitable survey tool for professors, courses, and performances in Korean universities. The 290 students who participated and 44 students do not participate in the financial support program were surveyed for 10 days. The characteristics of students were investigated by frequency analysis and technical statistics. The analysis of student collective characteristics used independent t and f-tests,and one-way ANOVA with IBM SPSS Statistics 22.0 for statistical purposes. Results - The p-value of the group receiving financial support and the group without financial support in active-collaborative learning is 0.167. The p-value of the economically supported group and the non-supported group of the faculty-student interaction is 0.281. The confidence coefficient of the active-collaborative learning questionnaire is 0.861. The reliability coefficient of the questionnaire for the faculty-student interaction questionnaire is 0.871. Conclusions - There are no clear differences in active-collaborative learning and faculty-student interaction between participating and non-participating students in the economic program.

• Earthquakes and Structures
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• v.26 no.6
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• pp.463-475
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• 2024

The study aims to investigate the pounding that occurs between the isolator's ring and slider of isolated structures resulting from excessive seismic excitation, while considering soil-structure interaction. The dynamic responses and poundings of structures subjected a series seismic records were comparatively analyzed for three different soil types and fixed-base structures. A series of parametric studies were conducted to thoroughly discuss the effects of the impact displacement ratio, the FPB friction coefficient ratio, and the radius ratio on the structural dynamic response when considering impact and SSI. It was found that the pounding is extremely brief, with an exceptionally large pounding force generated by impact, resulting in significant acceleration pulse. The acceleration and inter-story shear force of the structure experiencing pounding were greater than those without considering pounding. Sudden changes in the inter-story shear force between the first and second floors of the structure were also observed. The dynamic response of structures in soft ground was significantly lower than that of structures in other ground conditions under the same conditions, regardless of the earthquake wave exciting the structure. When the structure is influenced by pulse-type earthquake records, its dynamic response exhibits a trend of first intensifying and then weakening as the equivalent radius ratio and friction coefficient ratio increase. However, it increases with an increase in the pounding displacement ratio, equivalent radius ratio, friction coefficient ratio, and displacement ratio when the structures are subjected to non-pulse-type seismic record.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.555-560
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• 2008

Dynamic interaction analysis between actively controlled Maglev and bridge is carried out. For this, dynamic governing equation for 2-dof Maglev vehicle and optimal feedback control scheme of DOFC are developed. And then the dynamic effect of the 1st natural frequency of bridge, vehicle/bridge mass ratio and damping coefficient of bridge to the both of air-gap variations of UTM-01 maglev vehicle and bridge center maximum displacement response are investigated. From the results of numerical simulation, it is found that the 1st natural frequency of bridge, vehicle/bridge mass ratio and damping coefficient of bridge does not affect greatly within design velocity of the vehicle.

• Korean Journal of Metals and Materials
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• v.50 no.2
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• pp.116-121
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• 2012

Equilibria between Mn-Si melts and $MnO-SiO_2$ slags were studied at 1673 K and 1773 K in MnO crucibles to accurately determine the thermodynamic property of the Mn-Si melts. The Unified Interaction Parameter Formalism (UIPF) was used to describe the thermodynamic property of the Mn-Si liquid. Using the UIPF, the experimental results obtained in the present study were thermodynamically analyzed to determine the activity coefficient of Si at infinite dilution and the 1st- and 2nd-order self-interaction parameters of Si in the Mn-Si melts.

• Journal of applied mathematics & informatics
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• v.27 no.5_6
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• pp.1017-1031
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• 2009

The problem of interaction of surface water waves by small undulation at the bottom of a laterally unbounded sea is treated on the basis of linear water wave theory for both normal and oblique incidences. Perturbation analysis is employed to obtain the first order corrections to the reflection and transmission coefficients in terms of integrals involving the shape function c(x) representing the bottom undulation. Fourier transform method and residue theorem are applied to obtain these coefficients. As an example, a patch of sinusoidal ripples is considered in both the cases as the shape function. The principal conclusion is that the reflection coefficient is oscillatory in the ratio of twice the surface wave number to the wave number of the ripples. In particular, there is a Bragg resonance between the surface waves and the ripples, which is associated with high reflection of incident wave energy. The theoretical observations are validated computationally.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1770-1779
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• 1992

The present study investigated dynamically and thermally interacting droplets in a closely spaced tandem array. By measuring the velocity and diameter of the droplet traveling along the isothermal vertical plate drag coefficients and vaporization rates of droplets at certain location were obtained. During the experiment initial droplet spacings were less than 5, and initial droplet diameters were ranged between 280 .mu.m and 700 .mu.m Drag coefficients on closely spaced droplets were placed far below the standard drag coefficient, for which it was caused turbulence induced from aforelocating droplets also narrow spaces among droplets restricted heat transfer to droplets from hot gas flow. In addition evaporated vapor entrapted between droplets was major factor in delaying droplet vaporization. With the experimental results the drag coefficient was correlated with respect to Reynolds number for the droplet as follows : $c_{D}$ =2.4/Red.$^{0.37}$

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.2
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• pp.120-124
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• 1991

An interaction of turbulent boundary layer and local roughness effects was evaluated to investigate the shear frictional coefficient in diffuser. Clauser roughness function was applied to Karman's integral equation for governing equation. The roughness of overall and local diffuser surfaces were calculated using Cole's wall and wake law and Clauser's roughness function for turbulent boundary layer characteristics. The calculating results were compared with the experimental results of other paper. It shows some significant improyements for shear frictional coefficient. Computer code was then used to confirm the behavior of local frictional coefficient along with diffuser roughness surface for some reduction of shear flow stress.

• Current Optics and Photonics
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• v.5 no.2
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• pp.191-197
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• 2021

The anomalous propagation characteristics of a single Airy beam in nonlocal nonlinear medium are investigated by utilizing the split-step Fourier-transform method. We show that besides the normal straight propagation trajectory, the breathing solitons formed by the interaction between Airy beam and nonlocal nonlinear medium can propagate along the sinusoidal trajectory, and the anomalous trajectory can be modulated arbitrarily by altering the initial amplitude and the nonlocal nonlinear coefficient. In addition, the initial amplitude and the nonlocal nonlinear coefficient can have inverse impacts on the formation and transformation of the equilibrium state of spatial solitons, when the two parameters are larger than certain values. Therefore, the reversible transformation of the evolution dynamics of two soliton states can be realized by adjusting those two parameters properly. Finally, it is shown that the propagation properties of the solitons formed by the interaction between Airy beam and nonlocal nonlinear medium can be controlled arbitrarily, by adjusting the distribution factor and nonlocal coefficient.

• Steel and Composite Structures
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• v.4 no.5
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• pp.367-384
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• 2004

A numerical model based on the finite element technique is adopted to investigate the behavior and strength of thin-walled I-section beam-columns. The model considers both the material and geometric nonlinearities. The model results were first verified against some of the currently available experimental results. A parametric study was then performed using the numerical model and interaction diagrams for the investigated beam-columns have been presented. The effects of the web depth-to-thickness ratio, flange outstand-to-thickness ratio and bending moment-to-normal force ratio on the ultimate strength of thin-walled I-section beam-columns were scrutinized. The interaction equations adopted for beam columns design by the NAS (North American Specifications for the design of cold formed steel structural members) have been critically reviewed. An equation for the buckling coefficient which considers the interaction between local buckling of the flange and the web of a thin-walled I-section beam-column has been proposed.