• International Journal of Computer Science & Network Security
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• 제22권3호
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• pp.37-44
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• 2022

Plug-in Hybrid electric vehicles (PHEV) show great potential to reduce gas emission, improve fuel efficiency and offer more driving range flexibility. Moreover, PHEV help to preserve the eco-system, climate changes and reduce the high demand for fossil fuels. To address this; some basic components and energy resources have been used, such as batteries and proton exchange membrane (PEM) fuel cells (FCs). However, the FC remains unsatisfactory in terms of power density and response. In light of the above, an electric storage system (ESS) seems to be a promising solution to resolve this issue, especially when it comes to the transient phase. In addition to the FC, a storage system made-up of an ultra-battery UB is proposed within this paper. The association of the FC and the UB lead to the so-called Fuel Cell Battery Electric Vehicle (FCBEV). The energy consumption model of a FCBEV has been built considering the power losses of the fuel cell, electric motor, the state of charge (SOC) of the battery, and brakes. To do so, the implementing a reinforcement-learning energy management strategy (EMS) has been carried out and the fuel cell efficiency has been optimized while minimizing the hydrogen fuel consummation per 100km. Within this paper the adopted approach over numerous driving cycles of the FCBEV has shown promising results.

• IEMEK Journal of Embedded Systems and Applications
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• 제8권2호
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• pp.87-93
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• 2013

In this paper, we implemented and evaluated the performance of a vector-based rasterization algorithm of 3D graphics using a SIMD-based many-core processor that consists of 4,096 processing elements. In addition, we compared the performance and efficiency of the rasterization algorithm using the many-core processor and commercial GPU (Graphics Processing Unit) system which consists of 7 GPUs and each of which have 512 cores. Experimental results showed that the SIMD-based many-core processor outperforms the commercial GPU system in terms of execution time (3.13x speedup), energy efficiency (17.5x better), and area efficiency (13.3x better). These results demonstrate that the SIMD-based many-core processor has potential as an embedded mobile processor.

• Journal of the Korean Society of Combustion
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• 제18권3호
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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).

• Transactions of the Korean hydrogen and new energy society
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• 제28권6호
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• pp.601-609
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• 2017

Hydrogen is a clean, endlessly produced energy and it is easy to store and transfer. So, hydrogen is regarded as next generation energy. Among various ways for hydrogen production, the way to produce hydrogen by water electrolysis can effectively respond to fossil fuel's depletion or climate change. As interest in hydrogen has increased, related research has been actively conducted in many countries. In this study, we analyzed the performance characteristics and safety of water electrolysis system. In this study, we analyzed the performance characteristics and safety of water electrolysis system. The items for safety performance evaluation of the water electrolysis system were derived through analysis of international regulations, codes, and standards on hydrogen. Also, a prototype of the overall safety performance evaluation station was designed and developed. The demonstration test was performed with a prototype $10Nm^3/h$ class water electrolysis system that operated stably under various pressure conditions while measuring the stack and system efficiency. At 0.7MPa, the efficiency of the alkaline water electrolysis stack and the system that used in this study was 76.3% and 49.8% respectively. Through the GC analysis in produced $H_2$, the $N_2$ (5,157ppm) and $O_2$ (1,646 ppm) among Ar, $O_2$, $N_2$, CO and $CO_2$ confirmed as main impurities. It can be possible that the result of this study can apply to establish the safety standards for the hydrogen production system by water electrolysis.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제23권4호
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• pp.101-107
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• 2009

The energy efficiency of existing lighting appliances has continuously been improving due to the government aid such as rebate programs and information of energy saving, etc. However, the usage pattern of lighting appliance at this moment has more been increasing higher illumination and indirect lighting method according that the taste of customers has changed variously. This paper estimates the economic evaluation and simulation for FPL45[W] lamp & ballast instead of FPL55 lamp & ballast in order to study the governmental support to demand side management.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권4호
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• pp.1223-1247
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• 2012

The need for securing Wireless Sensor Networks (WSNs) is essential especially in mission critical fields such as military and medical applications. Security techniques that are used to secure any network depend on the security requirements that should be achieved to protect the network from different types of attacks. Furthermore, the characteristics of wireless networks should be taken into consideration when applying security techniques to these networks. In this paper, energy efficient Security Model for Tree-based Routing protocols (SMTR) is proposed. In SMTR, different attacks that could face any tree-based routing protocol in WSNs are studied to design a security reference model that achieves authentication and data integrity using either Message Authentication Code (MAC) or Digital Signature (DS) techniques. The SMTR communication and processing costs are mathematically analyzed. Moreover, SMTR evaluation is performed by firstly, evaluating several MAC and DS techniques by applying them to tree-based routing protocol and assess their efficiency in terms of their power requirements. Secondly, the results of this assessment are utilized to evaluate SMTR phases in terms of energy saving, packet delivery success ratio and network life time.

• Journal of Environmental Health Sciences
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• 제23권4호
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• pp.57-66
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• 1997

Successful energy conservation and good indcfor air quality (IAQ) are highly dependent on ventilation system. Air filtration is a primary solution of indoor air control strategies in terms of reducing energy consumption and improving ihdoor air quality. A conventional system with bypass filter, as it is called variable-air-volume/bypass filtration system (VAV/BPFS), is a variation of the conventional variable air volume (VAV) systems, which is designed to eliminate indoor air pollutant and to save energy. Bypass filtration system equipped with a high-efficiency particulate filter and carbon absorbent provides additional cleaned air into indoor environments and maintain good IAQ for human health. The objectives of this research were to compare the relative total decay rate of indoor air pollutant concentrations, and to develop a mathematical model simulating the performance of VAV/BPFS. All experiments were performed in chamber under the controlled conditions. The specific conclusions of this research are: 1. The VAV/BPFS system is more efficient than the VAV system in removing indoor air pollutant concentration. The total decay rates of aerosol, and total volatile organic compound (TVOC) for the VAV/BPFS system were higher than those of the conventional VAV system. 2. IAQ model predictions of each pollutant agree closely with the measured values. 3. According to IAQ model evaluation, reduction of outdoor supply air results in decreased dilution removal rate and on increased bypass filtration removal rate with the VAV/BPFS. As a results, we recommends the VAV/BPFS as an alternative to conventional VAV systems.

• Journal of Biosystems Engineering
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• 제40권2호
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• pp.137-144
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• 2015

Purpose: The high energy requirement of extraction of oil from jatropha seed and reduction of loss in oil content between whole seed and kernel of jatropha necessitate seed shelling. The purpose of this study is to develop and evaluate the performance of a jatropha seed shelling machine based on seed moisture content. Methods: A shelling machine was designed and constructed for jatropha seed. The components are frame, hopper, shelling chamber, concave, and blower with discharge units. The performance evaluation of the machine was carried out by determining parameters such as percentage of whole kernel recovered, percentage of broken kernel recovered, percentage of partially shelled seed, percentage of unshelled seed, machine capacity, machine efficiency, and shelling efficiency. All of the parameters were evaluated at five different moisture levels: 8.00%, 9.37%, 10.77%, 12.21%, and 13.68% w.b.). Results: The shelling efficiency of the machine increased with increase in seed moisture content; the percentage of whole kernel recovered and percentage of partially shelled seed decreased with increase in moisture content; and percentage of broken kernel, machine efficiency, and percentage of unshelled seed followed a sinusoidal trend with moisture content variation. Conclusion: The best operating condition for the shelling machine was at a moisture content of 8.00% w.b., at which the maximum percentage of whole kernel recovered was 23.23% at a shelling efficiency of 73.95%.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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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.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.109.1-109.1
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• 2011

KEPCO was operating power plants with diesel generators in 49 islands including Baekryeong-Do, and the generation capacity was about 66 MW in 2008. The cost of fuel is increasing by the international oil price inflation and continuous rise of oil price is predicted. For the stabilizing of electric power supply to the separate islands, renewable energy and fuel cell systems were considered. Hydrogen is made using renewable energy such as wind power and solar energy, and then a fuel cell system generates electricity with the stored hydrogen. Though the system efficiency is low, it is treated as the only way to secure the stable electric supply using renewable energy at this present. The analytic hierarchy process was used to select suitable candidate island for the system installation and 5 islands including Ulleung-Do were selected. Economic evaluation for the system composed of a kerosene generator, a wind power, an electrolysis, and a fuel cell system was conducted with levelized generation cost based on present value methode. As the result, the necessity of renewable energy combined generation system and micro grid composition in the candidated islands was confirmed. Henceforth, the development of an integration technology which connects micro grid to the total power grid will be needed.