• Transactions on Electrical and Electronic Materials
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• 제15권2호
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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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• 제1권4호
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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.

• 대한전기학회논문지
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• 제43권6호
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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.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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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.

• 대한조선학회지
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• 제24권2호
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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.

• 한국환경과학회지
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• 제25권6호
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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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• 제38권5호
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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.

• 대한토목학회논문집
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• 제33권2호
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• pp.631-642
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• 2013

현장지반의 공학적 특성을 파악하기 위한 콘 관입시험(Cone Penetration Test; CPT)은 원지반의 연속적인 강도 특성을 분석하여 다양한 지반변수를 손쉽게 획득할 수 있다는 점에서 널리 활용되고 있으며, 원심모형실험에서도 널리 활용되고 있다. 본 연구에서는 원심모형실험에서 콘선단저항치를 계측할 수 있는 직경이 10 mm인 소형 콘을 개발하고 원심모형실험에서의 적용성을 평가하였다. 개발된 콘으로 4자유도 로봇을 활용하여 원심모형 가속 상태에서 콘 관입시험을 수행하였다. 이 때, 원심가속도 수준을 4회 변화시켜 다양한 유효응력상태에서 콘 관입시험을 실험을 수행하였다. 그 결과, 얕은 관입깊이의 동일한 유효응력에서 콘 선단저항치는 g-level에 영향을 받으며, 선단저항치가 임계 깊이 도달하는 깊이는 g-level과 상대밀도가 커질수록 깊어짐을 확인하였다. 또한, 각 실험에서 임계 깊이에 도달한 선단저항치와 실내실험에서 획득한 지반물성을 이용하여 기존 경험식과 비교하였다.

• 한국지반환경공학회 논문집
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• 제15권9호
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• pp.87-92
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• 2014

지압형 앵커는 지반 자체를 지지기구로 활용하여 인발에 저항하는 구조이며 앵커의 인발저항력은 지반의 지압저항력과 확장날개의 확공부 공벽 압착에 의한 마찰저항력으로 구성된다. 특히 확공 지압형 앵커는 정착장 확공부에서 발생하는 지압저항력으로 인발에 저항하여 지반변형을 억제하기 위한 주동보강 방식의 구조이다. 본 연구는 확공 지압형 앵커의 지압저항력 산정을 위해 수행되었으며, 실모형실험으로 지압저항력을 산정하고 그 결과를 지반의 일축압축강도와 비교하였다. 실모형실험에서는 모형지반들의 일축압축강도를 8개의 풍화암 조건으로 모사하여 앵커 인장시험을 수행해 지압저항력을 측정하였다. 실험에서 도출된 지압저항력은 모사된 지반강도와 일련의 선형적 관계를 보였으며, 선형회귀분석을 통해 경험식을 제시하였다. 지압저항력은 실모형 실험 결과 일축압축강도 대비 약 13배로 산정되었고, 이론식에서 제시하고 있는 수치와 상당히 일치하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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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.