• Transactions on Electrical and Electronic Materials
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• v.15 no.2
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• pp.103-111
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• 2014

This paper investigates the output powers of PV modules by predicting three unknown parameters: reverse saturation current, and series and shunt resistances. A theoretical model using the non-uniform physical parameters of solar cells, including the temperature coefficients, voltage, current, series and shunt resistances, is proposed to obtain the I-V characteristics of PV modules. The solar irradiation effect is included in the model to improve the accuracy of the output power. Analytical and Newton methods are implemented in MATLAB to calculate a module output. Experimental data of the non-uniform solar cells for both serial and parallel connections are used to extend the implementation of the model based on the I-V equation of the equivalent circuit of the cells and to extend the application of the model to m by n modules configuration. Moreover, the theoretical model incorporates, for the first time, the variations of series and shunt resistances, reverse saturation current and irradiation for easy implementation in real power generation. Finally, this model can be useful in predicting the degradation of a PV system because of evaluating the variations of series and shunt resistances, which are critical in the reliability analysis of PV power generation.

• Membrane and Water Treatment
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• v.1 no.4
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• pp.297-316
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• 2010

Membrane fouling is one of the major operational concerns of membrane processes which results in loss of productivity. This paper investigates the ultrafiltration (UF) results of synthetic oil-in-water (o/w) emulsion using flat sheets of polysulfone (PSf) membrane synthesized with four different compositions. The aim is to identify the mechanisms responsible for the observed permeate flux reduction with time for different PSf membranes. The experiments were carried out at four transmembrane pressures i.e., 68.9 kPa, 103.4 kPa, 137.9 kPa and 172.4 kPa. Three initial oil concentrations i.e., 75 $mgL^{-1}$, 100 $mgL^{-1}$ and 200 $mgL^{-1}$ were considered. The resistance-in-series (RIS) model was applied to interpret the data and on that basis, the individual resistances were evaluated. The significances of these resistances were studied in relation to parameters, namely, transmembrane pressure and initial oil concentration. The total resistance to permeate flow is found to increase with increase in both transmembrane pressure and initial oil concentration while for higher oil concentration, resistance due to concentration polarization is found to be the prevailing resistance. The applicability of the constant pressure filtration models to the experimental data was also tested to explain the blocking process. The study shows that intermediate pore blocking is the dominant mechanism at the initial period of UF while in the later period, the fouling process is found to approach cake filtration like mechanism. However, the duration of pore blocking mechanism is different for different membranes depending on their morphological and permeation properties.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.6
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• pp.951-957
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• 1994

We present a new model for the series resistance of inverted-staggered amorphous silicon (a-Si) thin film transistors (TFT's) by employing the current spreading under the source and the drain contacts as well as the space charge limited current model. The calculated results based on our model have been in good agreements with the measured data over a wide range of applied voltage, gate-to-source and gate-to-drain overlap length, channel length, and operating temperature. Our model shows that the contribution of the series resistances to the current-voltage (I-V) characteristics of the a-Si TFT in the linear regime is more significant at low drain and high gate voltages, for short channel and small overlap length, and at low operating temperature, which have been verified successfully by the experimental measurements.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.671-674
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• 2005

The series parasitic resistances ($R_s$, $R_g$, $R_d$, $R_{sub}$) of BSIM3v3 RF MOSFET macro model were directly extracted from measured S-parameters in the GHz region by using simple 2-port parameter equations. Also, overlap capacitance and junction capacitance parameters were extracted by tuning $S_{11}$, $S_{12}$, and $S_{22}$ respectively while DC-parameters and all parasitic resistances are fixed at previously extracted values. These data are verified to be accurate by observing good correspondence between modeled and measured S-parameters up to 10GHz.

• Bulletin of the Society of Naval Architects of Korea
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• v.24 no.2
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• pp.11-19
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• 1987

A Series 60, $C_b=0.60$ model was tested in the towing tank of Seoul National University. Total resistance, hull attitude, wake distributions and wave measured at FR condition(free trim and sinkage) and FX condition(fixed trim and sinkage). From the measured data, residual, viscous and wave pattern resistance components were evaluated and compared. It is found that the changes in wetted surface area should be considered in predictions of frictional resistances, and can be easily found from hydrostatic data and measured mean sinkages without additional tests. Applications of the concept to the geosim tests of Series 60, Wigley, Lucy Ashton models show that the conventional extrapolation method can be improved considerably.

• Journal of Environmental Science International
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• v.25 no.6
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• pp.817-827
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• 2016

The resistance in series model has been frequently used for determination of various filtration resistance to correctly understand the membrane fouling behaviour in MBR (membrane bio-reactor) for wastewater treatment. The cake layer resistance ($R_c$) which is commonly determined by calculation of flux dataset that are obtained empirically before and after removing the cake layer on membrane surface. However, the calculated Rc values are very dependent on the cleaning methods adapted for removal of cake layer. This study investigated how the various cleaning options affect $R_c$. Seven different cleaning methods were employed: i) ultrasonication (100 W, 10 min), ii) ultrasonication (200 W, 60 min), iii) ultrasonication (400 W, 120 min), iv) water rinsing in a shaker (100 rpm, 10 min), v) water rinsing in a shaker (300 rpm, 60 min), vi) water rinsing, vii) sponge scrubbing. For the hydrophilic PES membrane, the cake layer removal efficiencies ranged from 64% to 10%, indicating that the removal of cake layer was highly dependent on the cleaning options. For the hydrophobic PVDF membrane, the cake layer removal efficiencies ranged from 79% to 97%. Consequently, a standardized method for cake layer removal to determine cake resistance ($R_c$) is needed for correct interpretation of the fouling phenomena.

• Steel and Composite Structures
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• v.38 no.5
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• pp.547-562
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• 2021

This paper aims to explore the mechanical behavior and moment-rotation model of blind bolted joints between concrete-filled double skin steel tubular columns and steel-concrete composite beams. For this type of joint, the inner tube and sandwiched concrete were additionally identified as basic components compared with CFST blind bolted joint. A modified moment-rotation model for this type of connection was developed, of which the compatibility condition and mechanical equilibrium were employed to determine the internal forces of basic components and neutral axis. Following this, load transfer mechanism among the inner tube, sandwiched concrete and outer tube was discussed to assert the action area of the components. Subsequently, assembly processes of basic coefficients in terms of their stiffness and resistances based on the component method by simplifying them as assemblages of springs in series or in parallel. Finally, an experimental investigation on four substructure joints with CFDST columns for validation purposes was carried out to capture the connection details. The predicted results derived from the mechanical models coincided well with the experimental results. It is demonstrated that the proposed mechanical model is capable of evaluating the complete moment-rotation relationships of blind bolted CFDST column composite connections.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.631-642
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• 2013

The standard CPT(Cone Penetration Test), which can be easily performed to investigate in-situ soil engineering properties, has been widely used. CPT are also widely being utilized in centrifuge model tests. In this study, a miniature cone with 10mm diameter was developed and its applicability in the centrifuge was evaluated. The developed miniature cone was equipped with a four degree-of-freedom in-flight robot. A series of cone penetration tests was performed under four centrifuge acceleration levels. As results, the cone resistances measured at the same confining stress within shallow penetration depth were affected by the centrifugal accelerations. The critical depth was proportional to the cone diameter and relative density. Cone resistances results below the critical depth and soil parameters obtained from the laboratory tests were compared with those by previously proposed empirical relations.

• Journal of the Korean GEO-environmental Society
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• v.15 no.9
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• pp.87-92
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• 2014

The Ground anchor is reinforcement to resist pull-out through ground that is used supports structure. The pull-out resistance of anchor is constructed by skin friction resistance from compression borehole wall in expanded wings and bearing pressure from the ground. Especially, underreamed ground anchor is reinforcement that adopts active reinforcement to prevent deformation of ground using bearing resistance generated reaming anchorage. This study is conducted to calculate bearing resistance of underreamed ground anchor. Realistic model tests were fulfilled to determine bearing resistance of anchor, and correlate results of tests to Uniaxial Compressive Strengths (UCS) of ground models that assumed weathered rock condition in 8 case. In a comprehensive series of the tests, the bearing resistances were measured by pull-out tests. The bearing resistances derived from tests have a linear correlation with UCS. We also suggest empirical equation between bearing resistance and UCS of rocks by single linear regression analyses. In test results of this study, the bearing resistances were evaluated approximately 13 times higher than UCS of the grounds, and it is qualitatively similar to numerical values of pull-out force derived from theory.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.506-508
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• 2008

In this work, we used impedance spectroscopy analysis to determine the effect of the $HfO_X$ treatment on the surface of ITO and to model the equivalent circuit for OLEDs. Devices with an ITO/Organic material/Al structure can be modeled as resistances and capacitances arranged in parallel or in series. The number of elements depends on the composition of the structure, essentially the number of layers, and the contacts.