• New & Renewable Energy
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• v.7 no.2
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• pp.10-17
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• 2011

Korea is the 11th largest energy consumption country and 96% of its total energy consumption depends on imports from overseas. Therefore it is a very important task to secure renewable energy sources which can reduce both the carbon-dioxide emission and dependency on overseas energy imports. Among the various renewable energy sources, organic wastes are important sources. In Korea, 113 million toe of methane is generated from organic wastes annually, but only 3.7% is effectively used for energy conversion. Thus, it is very important to make better use of organic wastes, especially for power generation. The goals of this project are to develope the fuel supplying system of Bio Gasturbine (GT) for 5MW-class co-generation system. The fuel supplying system mainly consists of $H_2S$ removal system, Bio Gas compression system, Siloxane removal system and moisture separating systems. The fuel requirement of 5MW-class GT is at around 60% of $CH_4$, $H_2S$ (<30 ppm), Siloxane(<10 mg/$nm^3$) and supply pressure (> 25 bar) from biogas compressor. Main mechnical charateristics of Bio Gasturbine system have the specific performance; 1) high speed turbine speed (12,840 rpm) 2) very clean emmission NOx (<50 ppm) 3) high efficiency of energy conversion rate. This paper focuses on the development of design technology for food waste biogas pretreatment system for 5MW-class biogas turbine. The study also has the plan to replace the fuel of gas turbine and other distributed power systems. As the increase of bioenergy, this system help to contribute to spread more New & Renewable Energy and the establishment of Renewable Portfolio Standards (RPS) for Korea.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1406-1411
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• 2008

The percentage of apartment houses in residential buildings has increased every year, and it result in higher energy consumption of residential buildings. After the house law could be amended to legalize the remodeling of the balcony, buyers and contractors prefer to choose the balcony remodeling type when they choose a house for installment sale. Many construction companies design an apartment house considering balcony remodeling. So, this paper compares the balcony remodeling type with the basic type(prior to remodeling balcony) by using the building energy rating system tool. The balcony remodeling type consumes heating energies more than the basic type, and is unable to receive high rating. If the balcony is remodeled, it is required to improve the performance of wall and window and reduce the area of remodeling balcony.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.3
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• pp.356-363
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• 2014

In this paper, we propose a new memristor-based crossbar array architecture, where a single memristor array and constant-term circuit are used to represent both plus-polarity and minus-polarity matrices. This is different from the previous crossbar array architecture which has two memristor arrays to represent plus-polarity and minus-polarity connection matrices, respectively. The proposed crossbar architecture is tested and verified to have the same performance with the previous crossbar architecture for applications of character recognition. For areal density, however, the proposed crossbar architecture is twice better than the previous architecture, because only single memristor array is used instead of two crossbar arrays. Moreover, the power consumption of the proposed architecture can be smaller by 48% than the previous one because the number of memristors in the proposed crossbar architecture is reduced to half compared to the previous crossbar architecture. From the high areal density and high energy efficiency, we can know that this newly proposed crossbar array architecture is very suitable to various applications of analog neuromorphic computing that demand high areal density and low energy consumption.

• International Journal of High-Rise Buildings
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• v.10 no.1
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• pp.35-43
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• 2021

With the rapid urbanization and growing energy use intensity in the built environment, the glazed curtainwall has become ever more important in the architectural practice and environmental stewardship. Besides its energy efficiency roles, window has been an important transparent component for daylight penetration and a view-out for occupant satisfaction. In response to the climate crisis caused by the built environment, this research focuses on the study of net-zero energy retrofitting by using a new building integrated photovoltaic (BIPV) curtainwall as a sustainable alternative to conventional window systems. Design variables such as building orientations, climate zones, energy attributes of BIPV curtainwalls, and glazed area were studied, to minimize energy consumption and discomfort hours for three cities representing hot (Miami, FL), mixed (Charlotte, NC), and cold (Minneapolis, MN). Parametric analysis and Pareto solutions are presented to provide a comprehensive explanation of the correlation between design variables and performance objectives for net-zero energy retrofitting applications.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.4
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• pp.22-32
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• 2022

To reduce energy consumption and CO₂ emission in building sector, a ground source heat pump system has been highly adopted due to its high efficient by many regulation. A certification system has been operated to distribute reliable and high-efficient heat pump units. In this study, the performance status of the recently certified ground source heat pump unit with components was investigated. All heat pump units certified from 2015 to 2020 were water to water heat pump types. Compared to the past, higher capacity systems over 400 kW have been certificed. The cooling COP of the heat pump unit based on certification criteria showed higher value than the heating COP. It is highly recommended to revise the certified criteria values considering operating conditions individually. Most of ground source heat pump units have employed scroll type compressors and plate type heat exchangers with HFC refrigerant.

• Journal of the Korea Society of Computer and Information
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• v.16 no.1
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• pp.1-9
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• 2011

Recently, as mobile multimedia devices are used more and more, the needs for high-performance and low-energy multimedia processors are increasing. Application-specific integrated circuits (ASIC) can meet the needed high performance for mobile multimedia, but they provide limited, if any, generality needed for various application requirements. DSP based systems can used for various types of applications due to their generality, but they require higher cost and energy consumption as well as less performance than ASICs. To solve this problem, this paper proposes a single instruction multiple data (SIMD) based many-core processor which supports high-performance and low-power image data processing while keeping generality. The proposed SIMD based many-core processor composed of 16 processing elements (PEs) exploits large data parallelism inherent in image data processing. Experimental results indicate that the proposed SIMD-based many-core processor higher performance (22 times better), energy efficiency (7 times better), and area efficiency (3 times better) than conversional commercial high-performance processors.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.1
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• pp.131-144
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• 2015

An extensive investigation of the influence of gate engineering on the CNTFET switching, high frequency and circuit level performance has been carried out. At device level, the effects of gate engineering on the switching and high frequency characteristics for CNTFET have been theoretically investigated by using a quantum kinetic model. It is revealed that hetero - material - gate CNTFET(HMG - CNTFET) structure can significantly reduce leakage current, enhance control ability of the gate on channel, and is more suitable for use in low power and high frequency circuits. At circuit level, using the HSPICE with look - up table(LUT) based Verilog - A models, the performance parameters of circuits have been calculated and the optimum combinations of ${\Phi}_{M1}/{\Phi}_{M2}/{\Phi}_{M3}$ have been concluded in terms of power consumption, average delay, stability, energy consumption and power - delay product(PDP). We show that, compared to a traditional CNTFET - based circuit, the one based on HMG - CNTFET has a significantly better performance (SNM, energy, PDP). In addition, results also illustrate that HMG - CNTFET circuits have a consistent trend in delay, power, and PDP with respect to the transistor size, indicating that gate engineering of CNTFETs is a promising technology. Our results may be useful for designing and optimizing CNTFET devices and circuits.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.296-297
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• 2014

United Nations Framework Convention on Climate Change(UNFCCC), an international treaty to prevent the regulation and global warming, has passed through the General Assembly for 17 times from 1992 to 2011. To create a performance plan specific, such as the Kyoto Protocol, it is to promote the reduction of energy consumption and greenhouse gases worldwide. In South Korea, Korea Infrastructure Safety and Technology Corporation(KISTEC) is working and supporting for developing method of green remodeling policy. Among several solutions, "Remodeling" ensures to increase the energy efficiency of buildings and to reduce the emissions of greenhouse gases, and consequently it could maintain buildings high efficiency. For remodeling projects, it is most important to determine construction plan including remodeling scopes and methods, while the plan has been determined by the engineer's background and experience. Therefore, this study aims at developing a method for selecting optimal skin system which has remarkable influence to energy performance of the buildings.

• KIEAE Journal
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• v.15 no.3
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• pp.49-56
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• 2015

Purpose: Due to recent increase on energy consumption for light in building, many studies to mitigate this issue have been conducted. Various researches have been carried out to suggest light shelf as one of the solutions, but researches for its reflectivity is very few. In fact, existing research on light shelf shows that utilizing more than 90% of high-illumination materials causes imbalance of glare and illuminance. Method: Therefore this research aimed to evaluate the performance of light shelves depending on reflectivity and to identify proper solution through test-bed. Result: The results are following: 1) Increased reflectivity generally contributed to increase of indoor illuminance but degrade uniformity factor related with indoor comfort of light environment. 2) The $0^{\circ}fixed$ light shelf with 75% of reflectivity and width of 300mm and 40mm appeared to consume more energy than other shelves. Therefore, it is analyzed as unsuitable. 3) This research was conducted by calculating appropriate angle of light shelf around winter and summer solstices and vernal/autumnal equinox. Based on this, performance evaluation was undertaken depending on reflectivity of movable light shelf, which is activated by external sources and can be applied with lower reflectivity than fixed shelf. However, one exception was a movable shelf with width of 600mm that increased light energy consumption when 75% of reflectivity was applied. 4) Performance evaluation of fixed and movable light shelf showed that the shelf with 80% of reflectivity came up with suitable results, but 75% of reflectivity may be applied depending on the width and angle of the shelf. This research is meaningful in that estimation of appropriate reflectivity of light shelf can resolve the glare problem and improve light environment, and further research would be desirable under more diverse conditions to identify proper solution.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.4
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• pp.373-381
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• 2012

To determine the performance characteristics of motorcycle engine using biogas for practical use, the intake system of a 110 cc motorcycle engine is properly modified to operate with biogas as a fuel. Biogas is a potentially renewable fuel for replacing gasoline in future, but it has high percentage of $CO_2$ that could lead to slow the burning rate of biogas-air mixture and cause instability in combustion. Thus, the performance characteristics of biogas-fueled motorcycle engines could be different from those of gasoline motorcycle engines. In this paper, the important parameters of performance characteristics (such as: power output, thermal efficiency, fuel consumption, exhaust emission,${\cdots}$) of biogas-fueled motorcycle engine are studied and estimated with change of engine speed and load. The obtained results when operating with biogas are used to compare with that of gasoline fuel under the same operating conditions. Engine speed in the experimental is changed from 1500 rpm (idle-mode) up to 3500 rpm by a step of 500 rpm. Engine load is changed from zero to maximum load with the help of an exciting voltage device from generator-type dynamometer. The experimental results show that the tested engine operated with richer biogas-air mixture than that of gasoline-air mixture under the same test conditions. Biogas-fueled engine gives a higher fuel consumption and lower thermal efficiency under the same power output. Brake thermal efficiency of biogas engine is found to be about 3% lower than gasoline-fueled motorcycle engine for whole range of speed. Exhaust emission of biogas-fueled motorcycle engine (such as: CO, HC) is found to be lower than the limitation level of the emission standards of Vietnam for motorcycle engines (CO <4.5% HC <1200 ppm).