• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.569-572
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• 2007

In this paper, research about SVM(stack voltage monitoring) module is written, which studied to detect the failure mode of stack and stop stack driving. It is important role for SVM module to monitor the cell voltage and also, transfer those data to Supervisor controller. SVM module needs accurate measurement to detect failure mode, because the cell voltage is very small value under a few [V]. For improving these cost and technical efficiency, the electric characteristic experiment is made with the measurement circuit designed by using precision resistor.

• The Transactions of the Korea Information Processing Society
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• v.7 no.5
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• pp.1500-1510
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• 2000

In this paper, a CDMA (Code Division Multiple Access) field engineering system is designed and implemented for managing cellular telecommunication base stations. For high quality of CDMA service, optimized cell planning is crucial. For such cell planning, base stations must be managed based on analysis of CDMA field dta. The proposed system consists of two modules: a measurement module and au analysis of CDMA field dta. eh proposed system consists of tow modules; a measurement module and an analysis module. The measurement module collects various CDMA field dta and displays them on a vector map in a real-time manner. The analysis module associates measured data with various related information, e.g. base station information, and process them statistically. The proposed system can drastically reduce base station management cost.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.71-72
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• 2008

This paper describes a circuit based simulation model for a Photovoltaic(PV) cell in order to estimate the electrical behavior of the solar cell module with changes of environmental parameters such as shunt resistance, series resistance, temperature and irradiance. An accurate I-V model of PV module is presented based on the Shockley diode model. The general model was implemented on Matlab scrip file, and used irradiance and temperature as variables and outputs of the I-V characteristic. A typical PV module was used for the evaluation, and results was compared with reference taken directly from the manufacturer's published curves leading to excellent agrement with the theoretical prediction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.13-14
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• 2008

In this paper, we analyze the electrical characteristics of PV depending on distance among solar cells before and after lamination process. From the result, the PV module's maximum power increases about 3.37% when solar cells's distance is 10mm. And the maximum power increases up to 8.42% when solar cells's maximum distance is 50mm. It is assumed that PV module's surface temperature decreases because of increasing distance between solar cells that would give high power generation. Also, short distance between solar cell and frame result in contamination on glass. When considering reduced maximum power caused by contaminant, from that, we can fabricated PV module of lower cost with high performance.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1775-1777
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• 2005

In this paper, maximum output of three different temperature conditions of the photovoltaic modules have been tested and compared to obtain the optimum conditions for the maximum power operation. Temperatures of the cell and module have been set to $20^{\circ}C$, $25^{\circ}C$ and $30^{circ}C$ under the constant light intensity of 1kW/$m^2$. 125${\times}$125mm 36 single crystal solar cells having 80 [W] each have been serially connected in the module. From the results, maximum output deviation of 4.67% has been obtained under the ceil temperature of $20^{\circ}C$ and module temperature of $30^{\circ}C$ while minimum deviation of 0.41${\sim}$0.92% has been measured under the same temperatures of cell and module. Therefore it has been found that the temperature of both cell and module should be fixed to $25^{\circ}C$ to obtain stable data unless the temperature coefficient should be compensated for the testing sample.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.3
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• pp.407-412
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• 2012

This study investigated the process of thermal-induced growth of micro-crack developed at the crystalline solar cell using EL image, determined the output characteristic according to the pattern of micro-crack, analyzed the I-V characteristic according to the pattern of crack growth, and predicted the output value using simulation. The purpose of this study was, therefore, to investigate the process of thermal-induced growth of micro-crack developed at the early stage of PV module completion using EL image, to analyze the resulting decrement of output and predict the output value using simulation. It was observed that the crack grew increasingly by the thermal condition, and accordingly the lowering of output was accelerated. The output values of crack patterns with various direction were predicted using simulation, resulting in close I-V curve with only around 4% of error rate. It is considered that it is possible to predict the electric characteristic of solar cell module using only pattern of micro-crack occurred at solar cell based on our results.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.45-50
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• 2011

The efficiency of solar cell was about 4[%] in initial stage of photovoltaic industry, but it has quite a lot of efficiency through technology advances. Today, the efficiency of c-Si solar cells is about 17 to 19[%] and the efficiency of PV modules is about 14 to 15 [%]. We called that electrical losses occurred in the Conversion of solar cells to PV modules are CTM loss(Cell To Module loss), the CTM loss typically has a value of about3~5[%]. The more efficiency of solar cell increase, differences are larger because the efficiency decrease owing to physical or technical problems occurred in the Conversion of solar cells to PV modules. In this study, the power loss factors occurred in the Conversion of solar cells to PV modules are analyzed and it is proposed that how to reduce losses of the PV module. The types of power loss factor are (1)losses of front glass and encapsulant(generally EVA sheet), (2)losses by sorting miss, (3)losses by interconnection, (4)losses by the field aging of PV modules. In further study, experimental and evaluation will be conducted to make demonstrate for proposed solutions.

• Journal of Integrative Natural Science
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• v.10 no.1
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• pp.58-63
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• 2017

Photovoltaic (PV) are generally modeled using mathematical equations that describe the PV system behavior. Most of the modeling approach is very simple in terms of that PV module temperature is calculated from nominal constant cell temperature such as ambient temperature and incoming solar irradiance. In this paper, we newly present MATLAB model particularly embedding the effect of wind speed to describe more accurate cell temperature. For analyses and validate purpose of the proposed model, solar power is obtained and compared with and without wind speed from the 50Wp PV module provided by vendor datasheet. In the simulation result, we found that power output of the module is increased to 0.37% in terms of cell temperature a degreed down when we consider the wind speed in the model. This result is well corresponded with the well-known fact that normal PV is 0.4% power changed by cell temperature a degree difference. Therefore it shows that our modeling method with wind speed is more appropriate than the methods without the wind speed effect.

• Journal of Electrochemical Science and Technology
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• v.12 no.4
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• pp.415-423
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• 2021

For a battery module where single cells are connected in series, the single cells should each have a similar state of charge (SOC) to prevent them from being exposed to an overcharge or over-discharge during charge-discharge cycling. To detect the existence of unbalanced SOC cells in a battery module, we propose a simple measurement method using a single-frequency response of electrochemical impedance spectroscopy (EIS). For a commercially available graphite/nickel-cobalt-aluminum-oxide lithium-ion cell, the cell impedance increases significantly below SOC20%, while the impedance in the medium SOC region (SOC20%-SOC80%) remains low with only minor changes. This impedance behavior is mostly due to the elementary processes of cathode reactions in the cell. Among the impedance values (Z, Z', Z"), the imaginary component of Z" regarding cathode reactions changes heavily as a function of SOC, in particular, when the EIS measurement is performed around 0.1 Hz. Thanks to the significant difference in the time constant of cathode reactions between ≤SOC10% and ≥SOC20%, a single-frequency EIS measurement enlarges the difference in impedance between balanced and unbalanced cells in the module and facilitates an ~80% improvement in the detection signal compared to results with conventional EIS measurements.

• Journal of the Korean Solar Energy Society
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• v.37 no.4
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• pp.1-11
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• 2017

Most PV modules are fabricated by 6 cell-strings with solar cells connected in series. Moreover, bypass diodes are generally installed every 2 cell-strings to prevent PV modules from a damage induced by current mismatch or partial shading. But, in the case of special purpose PV module, like as BIPV (Building Integrated Photovoltaic), the number of cell-strings per module varies according to its size. Differ from a module employing even cell-strings, the configuration of bypass diode should be optimized in the PV module with odd strings because of oppositely facing electrodes. Hence, in this study, electrical characteristics of special purposed PV module with odd string was empirically and theoretically studied depending on arrangement of bypass diode. Here, we assumed that PV module has 3 strings and the number of bypass diodes in the system varies from 2 to 6. In case of 2 bypass diodes, shading on a center string increases short circuit current of the module, because of a parallel circuit induced by 2 bypass diodes connected to center string. Also, the loss is larger, as the shading area in the center string is enlarged. Thus, maximum power of the PV module with 2 bypass diode decreases by up to 59 (%) when shading area varies from 50 to 90 (%). On the other hand, In case of 3 and 6 bypass diodes, the maximum power reduction was within about 3 (W), even the shading area changes from 50 to 90 (%). As a result, It is an alternative to arrange the bypass diode by each string or one bypass diode in the PV module in order to completely bypass current in case of shading, when PV module with odd string are fabricated.