• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.89-91
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• 2008

The photovoltaic industry is growing at a tremendous speed. And it can be one of the key factors for success in the photovoltaic business to choose a suitable system, and setting it up right so as to get a maximum efficiency of the site. Therefore, it is regarded to be necessary to research the efficiency of systems to catch maximum photovoltaic energy. In this research, the expected power generation efficiencies are analysed, and compared with each other. This research considered the direct sunlight only, and the angle between the direction of solar panel and sunlight as factors to affect the power generation. Therefore, only rough analyses and estimations are found on 3 systems of fixed system, double-axes tracking system, and horizontal tracking system.

• Biomolecules & Therapeutics
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• v.25 no.4
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• pp.362-366
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• 2017

Direct conversion by trans-differentiation is of growing interest in cell therapy for incurable diseases. The efficiency of cell reprogramming and functionality of converted cells are important considerations in cell transplantation therapy. Here, we compared two representative protocols for the generation of induced-oligodendrocyte progenitor cells (iOPCs) from mouse and rat fibroblasts. Then, we showed that induction of Nkx6.2, Olig2, and Sox10 (NOS) was more effective in mouse fibroblasts and that induction of Olig2, Sox10, and Zfp536 (OSZ) was more effective at reprogramming iOPCs from rat fibroblasts. However, OSZ-iOPCs did not show greater proliferation than NOS-induced cells. Because the efficiency of iOPCs generation appears to differ between cell species depending on transcription factors and culture conditions, it is important to select appropriate methods for efficient reprogramming.

• Journal of the Korean Society of Combustion
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• v.18 no.3
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• pp.1-8
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• 2013

Thermodynamic and economic analyses of various types of gas turbine combined cycle power plants have been performed to establish criteria for optimization of power plants. The concept of efficiency, in terms of the difference in energy levels of electricity and heat, was introduced. The efficiency of power and heat generation by power plants with other purposes was estimated, and power generation costs were figured out for various types of combined heat and power plants(i.e., fired and unfired, condensing and non-condensing modes, single or double pressure HRSG).

• Journal of the Semiconductor & Display Technology
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• v.18 no.2
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• pp.32-37
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• 2019

In this paper, we have designed a solar photovoltaic system to attach solar photovoltaic modules to each module and develop the best efficiency in each module. The efficiency of the designed solar panel optimizer was more than 99.27% and MPPT efficiency of 99.66%. In addition, the monitoring of power generation and abnormal operation phenomenon in each optimum period and tracking for failure location of specific photovoltaic module have improved the utilization rate of photovoltaic power generation. Wired and wireless communication methods has been proposed to monitor the power generation and operation status of the solar panel optimizer. For this purpose, the RS485 communication was used for wire communication and Zigbee communication was used for wireless communication to monitor the status of each module in real time. It is shown that communication redundancy can be achieved through the proposed method, and the possibility of commercialization is suggested.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.1
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• pp.71-78
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• 2022

With the advent of cutting-edge technology, renewable energy is significantly considered as alternative resources to supply electric power. However, many barriers such as energy intermittency, high initial installation cost, and low-efficiency generation challenged building new infrastructure with clean energy. Efforts reducing greenhouse gas emissions and reliance on fossil fuels resulted in the decentralization of power generation like distributed energy resource (DER). This paper is to introduce and evaluate the feasibility of building-integrated photovoltaics (BIPV) in a high-rise building in Ulsan. To optimize BIPV, a variety of methods to minimize efficiency decrease and maximize electric power generation after installing BIPV on the building's facade are suggested. The variables causing power losses are analyzed. By utilizing System Advisor Model (SAM), actual power generated from solar panels is measured by Thin-film PV, Mono-crystalline PV, and Poly-crystalline PV.

• Advances in Energy Research
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• v.8 no.3
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• pp.125-136
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• 2022

Entropy generation along with exergetic analysis is carried out using turbulent nanofluid flow in the heat exchanger. To obtain the optimized percentage constituent of nanofluid, the nanofluid volume concentrations is varied for the given input conditions. For different Reynolds number of the fluid and heat capacity rate ratio between the streams, the heat transfer improvements are studied in terms of nano particles diameter. Parametric analysis is carried out for a counterflow heat exchanger using turbulent nanofluid flow with exergetic efficiency along with entropy generation number as performance parameters. The exergetic efficiency provides realistic approach in the design of nanofluid applications in heat exchanger leading to conservation of energy.

• Journal of the Semiconductor & Display Technology
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• v.17 no.1
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• pp.40-44
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• 2018

In this paper, the efficiency of the solar system is lowered due to the partial shading such as the environmental factors of the solar panel. In order to solve this problem, a DC OPTIMIZER is proposed for a maximum power generation system of a photovoltaic panel. The proposed DC OPTIMIZER is composed of a buck structure that performs the maximum power point tracking (MPPT) control of each module of the solar panel, thus maximizing the efficiency. In order to verify the proposed DC Optimizer, the efficiency was measured by varying the irradiance using a solar simulator instead of the solar panel. As a result, it showed high efficiency characteristics as the maximum energy conversion efficiency was 99.3% at $800w/m^2$, $900w/m^2$, and the average efficiency was 99.06% excluding $100w/m^2$. The maximum efficiency of MPPT was 99.97% at $200w/m^2$, efficiency showed excellent performance.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.2
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• pp.141-148
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• 2023

The thermodynamic performance of the electrochemical hydrogen compressor was analyzed to perform a comparative analysis with the performance of the mechanical compressor. The performance was analyzed through the applied current and the measured voltage value. The test results showed that the efficiency of the electrochemical hydrogen compressor was high in the low current density range. In addition, it was confirmed that the amount of increasing compress work of the electrochemical hydrogen compressor is smaller than that of the mechanical compressor. Therefore, it is expected to have higher efficiency than mechanical compression when compressed with a sufficiently high-pressure range.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.1
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• pp.40-47
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• 2024

Ammonia is drawing attention as carbon free fuel due to its ease of storage and transportation compared to hydrogen. This study suggests ammonia fueled solid oxide fuel cell (SOFC) system with electrochemical hydrogen compressor (EHC)-based recirculation. Performance of electrochemical hydrogen pump is based on the experimental data under varying hydrogen and nitrogen concentration. As a result, the suggested system shows 62.04% net electrical efficiency. The efficiency is 10.33% point higher compared to simple standalone SOFC system (51.71%), but 0.02% point lower compared to blower-based recirculation system (62.06%). Further improvement in the EHC-based SOFC recirculation system can be achieved with EHC performance improvement.

• Journal of Information Technology Services
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• v.18 no.1
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• pp.79-90
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• 2019

Maximizing energy efficiency minimizes the energy consumption of computation, storage and communications required for IT services, resulting in economic and environmental benefits. Recent advancement of flash and next generation non-volatile memory technology and price decrease of those memories have led to the rise of so-called AFA (All-Flash Array) storage devices made of flash or next generation non-volatile memory. Currently, the AFA devices are rapidly replacing traditional storages in the high-performance servers due to their fast input/output characteristics. However, it is not well known how effective the energy efficiency of the AFA devices in the real world. This paper shows input/output performance and power consumption of the AFA devices measured on the Linux XFS file system via experiments and discusses energy efficiency of the AFA devices in the real world.