• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.394-399
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• 2009

Since some decades ago, there has been a concern for resource depletion and environmental pollution associated with building properties. In addressing such impact of the built environment, there is a recognition of the existence of alternative building materials, fuels for energy supply as well as technologies for waste handling and disposal. Nevertheless, for long time, the choice between such alternatives was dictated by factors such as differences in prices and aesthetic values. A new important dimension in discriminating between different options is the environmental dimension. This aspect is important since buildings are one of the spatially big new additions to the natural environment that consume a lot of materials and energy during their long lifetime. Thus, with the environmental dimension kept in mind, a existing cost estimation needs to be changed. A new cost assessment method, Life Cycle Cost, should calculate overall costs with dimensional factors: investment and utility costs as well as maintenance costs over the lifetime of the building. Aiming to give an overview of the present status of Building Life Cycle Assessment(LCA) tools as a basis for further research and development including economic performance, this paper describes and compares 3 different tools for Life Cycle Assessment(LCA) and economic analysis of the green buildings. This paper compared these approaches based on various aspects. These include economic analysis method, evaluation duration, data of results(index). Use of the comparison analysis is to produce a better picture and indicate profits and shortcomings for the tools as a group; thus providing important direction improvement of LCA tool as well as further research and development of this group of tools.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.2
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• pp.169-176
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• 2020

There is a growing interest in hydrogen energy utilization since an alternative energy development has been demanded due to the depletion of fossil fuels. Hydrogen is produced by the reforming reaction of natural gas and biogas, and the electrolysis of water. An solid oxide electrolyte cell (SOEC) is reversible system that generates hydrogen by electrolyzing the superheated steam or producing the electricity from a fuel cell by hydrogen. If the water can be converted into steam by waste heat from other processes it is more efficient for high-temperature electrolysis to convert steam directly. The reasons are based upon the more favorable thermodynamic and electrochemical kinetic conditions for the reaction. In the present study, steam at over 180℃ and 3.4 bars generated from a boiler were converted into superheated steam at over 700℃ and 3 bars using a cylindrical steam superheater as well as the waste heat of the exhaust gas at 900℃ from a solid refuse fuel combustor. Superheated steam at over 700℃ was then supplied to a high-temperature SOEC to increase the hydrogen production efficiency of water electrolysis. Computational fluid dynamics (CFD) analysis was conducted on the effects of the number of 90° elbow connector for piping, insulation types and insulation layers of pipe on the exit temperature using a commercial Fluent simulator. For two pre-heater injection method of steam inlet and ceramic wool insulation of 100 mm thickness, the highest inlet temperature of SOEC was 744℃ at 5.9 bar.

• Resources Recycling
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• v.26 no.2
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• pp.33-38
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• 2017

Waste can be utilized as secondary or alternative fuel. Solid recovered fuel (SRF) and dried sewage sludge were combusted to investigate heavy metal emissions from their combusiton in this study. Content of copper (Cu), chromium (Cr), cadmium (Cd), nickel (Ni), zinc (Zn), lead (Pb), arsenic (As) and mercury (Hg) of coal, SRF and dried sewage sludge were determined, respectively. Concentrations of these heavy metals in the combustion flue gas were also determined. As a result, emissions of gas-phase Cu, Cr, Cd, Ni, Zn, Pb and As compounds were found to be little. However, a significant amount of gas-phase Hg was emitted from combustion of coal, SRF and dried sewage sludge. While SRF showed a high mercury oxidation percentage in its combustion flue gas, dried sewage sludge showed a high level of gaseous mercury emission.

• Environmental Engineering Research
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• v.23 no.3
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• pp.250-257
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• 2018

We developed new composites by combining the solid waste from Low-Density Polyethylene in the form of plastic bag (PB) and biomass from rice husk (RH),in the form of $(RH)_x(PB)_{1-x}$ (x = (1, 0.9, 0.7, 0.5)), as alternative fuels for electrical energy sources, and for providing the best solution to reduce environmental pollution. Elemental compositions were obtained by using proximate analysis, ultimate analysis, and X-ray fluorescence spectroscopy, and the thermal characteristics were obtained from thermogravimetric analysis. The compositions of carbon and hydrogen from the ultimate analysis show significant increases of 20-30% with increasing PB in the composite. The activation energy for RH is 101.22 kJ/mol; for x = 0.9 and 0.7, this increases by 4 and 6 magnitude, respectively, and for x = 0.5, shows remarkable increase to 165.30 kJ/mol. The range of temperature of about $480-660^{\circ}C$ is required for combustion of the composites $(RH)_x(PB)_{1-x}$ (x = (1, 0.9, 0.7, 0.5)) to perform the complete combustion process and produce high energy. In addition, the calorific value was determined by using bomb calorimetry, and shows value for RH of 13.44 MJ/kg, which increases about 30-40% with increasing PB content, indicating that PB has a strong effect of increasing the energy realized to generate electricity.

• Journal of Energy Engineering
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• v.13 no.4
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• pp.311-318
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• 2004

In the present study, the combustion characteristics of methane and hydrogen-supplemented methane as alternative fuels for automotive vehicles were investigated at various hydrogen substitution rate, ignition position and ignition methods in a CVCC. The main results obtained from the study can be summarized as follow. In case of center ignition and neat methane-air mixture, the flame propagation processes are propagated with an elliptical shape, but they are changed an instable elliptical shape flame with very regular cells and higher velocity by increasing the hydrogen supplement rate. In case of side, 0.5R ignition and neat methane-air mixture, the flame propagation processes are propagated with an instable elliptical shape flame, but they are changed from an instable elliptical shape to wedge shape flame with very irregular cells and higher velocity by increasing the hydrogen supplement rate. Although the flame propagation shape with ignition position and ignition devices was not differ, the flame area of MSCDI device was a little larger than it of CDI device at the same time.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.193-200
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• 2007

Natural gas is one of the most promising alternatives to gasoline and diesel fuels because of its lower harmful emissions, including $CO_2$, and high thermal efficiency. In particular, natural gas is seen as an alternative fuel for heavy-duty Diesel Engines because of the lower resulting emissions of PM, $CO_2$ and $NO_x$. Almost all CNG vehicles use the PFI-type Engine. However, PFI-type CNG Engines have a lower brake horse power, because of reduced volumetric efficiency and lower burning speed. This is a result of gaseous charge and the time losses increase as compared with the DI-type. This study was conducted to investigate the effect of injection conditions (early injection mode, late injection mode) on the combustion phenomena and performances in the or CNG Engine. A DI Diesel Engine with the same specifications used in a previous study was modified to a DI CNG Engine, and injection pressure was constantly kept at 60bar by a two-stage pressure-reducing type regulator. In this study, excess air ratios were varied from 1.0 to the lean limit, at the load conditions 50% throttle open rate and 1700rpm. The combustion characteristics of the or CNG Engine - such as in-cylinder pressure, indicated thermal efficiency, cycle-by-cycle variation, combustion duration and emissions - were investigated. Through this method, it was possible to verify that the combustion duration, the lean limit and the emissions were improved by control of injection timing and the stratified mixture conditions. And combustion duration is affected by not only excess air ratio, injection timing and position of piston but gas flow condition.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.5
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• pp.125-134
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• 2018

Recently, interest in alternative energy has been increasing to reduce greenhouse gas emissions and fossil fuel consumption in accordance with the United Nations Framework Convention on Climate Change(UNFCCC). Accordingly, there is a need to use waste heat that unused throughout industrial systems for lowering the concentration of energy on fossil fuels. In particular, government support projects for the energy recycling of agriculture and fisheries such as cultivation of tropical crops and aquaculture are being actively carried out by utilizing waste heat and thermal effluents caused from large-scale industrial complexes including power plants. The study was conducted on supplier (power plant), consumer (farmer) and stakeholders (constructor and local governments) of domestic demonstration areas using waste heat that is abandoned from the power plant in the form of thermal effluents. It investigated the overall improvement and feasibility of government funded projects through field interviews and questionnaire-type surveys. The results of this study are expected to provide basic directions for the operation of the project in terms of nationwide expansion and diffusion of the heat source supply project at horticultural greenhouse by utilizing the thermal effluents from power plant.

• Journal of the Korean Institute of Gas
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• v.20 no.1
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• pp.52-61
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• 2016

Liquefied petroleum gas is regarded as a promising alternative fuel as it is eco-friendly, has good energy efficiency and output performance, practically and has high cost competitiveness over competing fuels. In spark-ignition engine, direct injection technology improves engine volumetric efficiency apparently and operates engine using the stratified charge that has relatively higher combustion efficiency. This study designed a combustion chamber equipped with visualization system by applying gasoline direct injection engine principle. In doing so, the study recorded and analyzed ignition probability and flame propagation process of spark-ignited direct injection LPG in a digital way. The result can contribute as a basic resource widespread for spark-ignited direct injection LPG engine design and optimization extensively.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.4
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• pp.32-42
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• 2012

Wood biomass including forest residues, waste wood, and construction residuals has been widely generated in Korea, but forest biomass from the National Forest Management Operation Project plays a big role in generating wood biomass. Unfortunately the promotion policy of woody energy organized by the Forest Service in Korea concentrates more on demand creation rather than on supply expansion. Therefore, in order to utilize insufficient wood resources effectively, it is greatly required to develop uses for maximizing their added value. In particular, more attention to the use of the second generation biomass has been paid in foreign countries because there is a threshold that the first generation biomass cannot produce enough biofuel without threatening food supplies and biodiversity. In Korea, wood pellets are regarded as the alternative clean fuels to oils and coals that emit green house gases into the atmosphere. However, using wood as pellet raw materials can not be an economic way because the value of wood disappears right after burning in the boiler in spite of its contribution to the decrease of carbon emission. Differently from wood pellets, kraft pulping process using woody biomass produces black liquor as a by-product which can be used to generate electricity, bioenergy and biochemicals through gasification. Thus, it can be more economical to make a torrefaction of lignocellulosic biomass such as low-quality wood and agricultural leftovers as raw materials of pellets.

• Journal of Ocean Engineering and Technology
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• v.34 no.5
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• pp.351-360
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• 2020

Of late, demand for test sites for marine equipment such as ASV, AUV, ROV, and various underwater sensors is increasing. The authors have focused on an oscillating water column (OWC), which is being constructed near Chagwido Island Jeju, as one of the test-sites. The main objective of the OWC is to produce wave energy and develop technologies. It has been built in the sea approximately 1 km off the coast. It has berth accommodation and some rooms that can be used as laboratories. To investigate the feasibility of its usage as a test site for marine equipment, we acquired bathymetric data around the OWC by using a multi-beam echo sounder and a single-beam scanning sonar. The accessibility of the OWC from nearby ports and the use of support vessels or ships were also investigated. 3D point cloud data from the multi-beam echo sounder and 2D acoustic images from the scanning sonar are expected to be used as references for identifying changes over time. In addition, through these experiments, we derived a procedure to use this facility as a test site by using the IDEF0 functional modelling method. Based on this preliminary investigation and previously reported examples, we determined the general conditions and preferences for evaluating the performance of various marine equipment heuristically. Finally, we developed five applications that were derived from this investigation.