• Journal of Electrical Engineering and Technology
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• v.7 no.4
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• pp.524-529
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• 2012

This paper proposes a novel control strategy of a PV tracking system considering the shadow influence. If distance of between PV arrays is not enough, shadow can be occurred to PV module. In PV system, if shadow is occurred to PV modules then PV modules operates reverses bias, and will eventually cause hot-spot and loss. To reduce loss by shadow influence, this paper proposes shadow compensation algorithm using distance between arrays and shadow length of array. The distance between arrays is calculated by using azimuth of solar, and length of array shadow is calculated using by altitude of solar. The shadow compensation algorithm proposed in this paper compares distance between arrays and length of array shadow. When the shadow length is longer than the distance between arrays, the algorithm adjusts altitude of array to avoid the shadow effects. The control algorithm proposed in this paper proves validity through compared with conventional algorithm and proposes experiment result.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.6
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• pp.994-1002
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• 2008

In this paper a novel tracking system is described, regarding the influence of shadow between array, aimed at improving the efficiency of PV tracking system. Comparing with a building site versus capacity power, domestic solar powers have a limited siting. Therefore, each array interferes with the shadow of other arrays. The loss by influence of those shadow can be compensated for by means of control algorithm of the tracking device. The paper suggests a method controlling an altitude for length which is received the shadow influence of PV array. By using an azimuth of current solar position and the length between arrays, the controller of tracking device is able to calculate the length between actual arrays and make a comparison of the shadow length at a specific time with the length between arrays. When the shadow length is longer than the length between arrays, the controller of tracking device can adjust a position by compensating error altitude of the length between arrays at an altitude of current solar position. In the paper, we develop the control algorithm able to minimize the loss caused by the influence of shadow on the PV tracking system, and compared this with conventional output system. The controller has been tested in the laboratory with proposed algorithm and shows excellent performance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.2
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• pp.36-44
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• 2013

This paper proposes the reconfiguration of PV module considering shadow influence of photovoltaic system. The PV system is consisted series-parallel connection of PV module. The voltage and current between PV modules become unbalance when shadow occurs to PV module. If shadow occurs to the series connection PV module, the output current is limited to current of shaded PV module. Also if shadow occurs to the parallel connection PV module, the output voltage is limited to voltage of shaded PV module. These problems are caused power loss. Therefore, the PV module in this paper consist using the fixed module and variable module by shaded conditions. The reconfiguration of PV module can compensates the shadow influence by changing connection of a variable module when shadow is occurred to PV module. A validity of the reconfiguration of PV module proposed in this paper proves through comparing with performance of conventional PV module.

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.135-141
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• 2008

In this paper a novel tracking system is described, regarding the influence of shadow between array, aimed at improving the efficiency of PV tracking system. Comparing with a building site versus capacity power, domestic solar powers have a limited siting. Therefore, each array interferes with the shadow of other arrays. The loss by influence of those shadow can be compensated for by means of control algorithm of the tracking device. The paper suggests a method controlling an altitude for length which is received the shadow influence of PV array. By using an azimuth of current solar position and the length between arrays, the controller of tracking device is able to calculate the length between actual arrays and make a comparison of the shadow length at a specific time with the length between arrays. When the shadow length is longer than the length between arrays, the controller of tracking device can adjust a position by compensating error altitude of the length between arrays at an altitude of current solar position. In the paper, we develop the control algorithm able to minimize the loss caused by the influence of shadow on the PV tracking system, and compared this with conventional output system. The controller has been tested in the laboratory with proposed algorithm and shows excellent performance

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.411-414
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• 2008

In this paper a novel tracking system is described, regarding the influence of shadow between array, aimed at improving the efficiency of PV tracking system. The loss by influence of those shadow can be compensated for by means of control algorithm of the tracking device. The paper suggests a method controlling an altitude for length which is received the shadow influence of PV array. By using an azimuth of current solar position and the length between arrays, the controller of tracking device is able to calculate the length between actual arrays and make a comparison of the shadow length at a specific time with the length between arrays. In the paper, we develop the control algorithm able to minimize the loss caused by the influence of shadow on the PV tracking system, and compared this with conventional output system. The controller has been tested in the laboratory with proposed algorithm and shows excellent performance

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.5
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• pp.21-33
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• 2012

This paper presents the new maximum power point tracking(MPPT) control of the photovoltaic(PV) module integrated converter(MIC) system considering the shadow influence. The output characteristics of the solar cell is a nonlinear and affected by a temperature, the solar radiation and influence of a shadow. Particularly, MIC system is very sensitive to the shadow influence because the capacity is very small. In order to increase an output and efficiency of the solar power generation, the maximum power point(MPP) obeying control are necessary. Conventional perturbation and observation(PO) and Incremental conductance(IC) are the method finding MPP by the continued self-excitation vibration. The MPPT control is unable to be performed by rapid output change affected by the shadow. To solve this problem, the new control algorithm of the multi-level in which the step value changes by output change is presented. In case there are the solar radiation, a temperature and shadow influence, the presented algorithm treats and compares the conventional control algorithm and output error. In addition, the validity of the algorithm is proved. through the output error response characteristics.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.5
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• pp.521-531
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• 2011

This paper presents the variable perturbation and observation(VPO) maximum power point tracking(MPPT) control of the photovoltaic(PV) system considering the shadow influence. The output characteristics of the solar cell is a nonlinear and affected by a temperature, the solar radiation and influence of a shadow. MPPT control is a very important technique in order to increase an output and efficiency of the solar power generation. Conventional perturbation and observation(PO) and incremental conductance(IC) are the method finding MPP by the continued self-excitation vibration. The MPPT control is unable to be performed by rapid output change affected by the shadow. To solve this problem, this paper proposes the VPO MPPT algorithm which changes step size according to output variation. The response characteristics of VPO MPPT algorithm proposed in this paper compares with response characteristics of conventional MPPT algorithm about the radiation, temperature and shadow influence. The validity of the algorithm proposed in this paper prove through the results of the comparisons.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.357-359
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• 2003

There is various problem in grasping change of vegetation by NDVI, PVI, etc. It is very difficult especially to remove various noise ingredients in the received satellite data. Until now, it is difficult to compensate for shadow effect when NDVI is used in vegetation analysis. The essence of this study is to describe data simulation and then applied the result to the NOAA AVHRR data. When a pixel contains shadow more than 60% then this pixe1 is extracted for shadow effects on NDVI.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1384-1385
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• 2011

This paper presents the active maximum power point tracking(MPPT) control of the photovoltaic(PV) module integrated converter(MIC) system considering the shadow influence. Conventional perturbation and observation(PO) and incremental conductance(IC) are the method finding MPP by the continued self-excitation vibration. The MPPT control is unable to be performed by rapid output change affected by the shadow. To solve this problem, the active MPPT in which the step value changes by output change is presented. In case there are the solar radiation, a temperature and shadow influence, the presented algorithm treats and compares the conventional control algorithm and output error. In addition, the validity of the algorithm is proved through the output error response characteristics.

• The Journal of Information Systems
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• v.32 no.2
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• pp.25-43
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• 2023

Purpose In online delivery platforms, platform workers are required to perform both platform labor, which is compensated with immediate wages, and shadow work which is a kind of unpaid job to support the platform labor. Thus, the objective of this study is to empirically examine how platform workers' platform labor and shadow work affect their job burnout and their turnover intention in the online delivery platform context. Design/methodology/approach This study developed a research model by employing platform labor and shadow work to influence job burnout and turnover intention. This study also tested the model by partial least square techniques after collecting 169 cross-sectional data from food delivery riders in Korea. Findings This study found that both platform labor and shadow work affected platform workers' job burnout. In addition, the results showed that shadow work influenced their turnover intention while platform labor did not affect the turnover intention. Based on the results, this study contributed to relevant researchers who are interested in platform contexts by offering measurable constructs on platform labor and shadow work. In addition, this study could provide practitioners with practical implications on managing platform workers.