• New & Renewable Energy
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• v.5 no.2
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• pp.15-24
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• 2009

As new small scale LFG (landfill gas) energy project model which can improve economic feasibility limited due to the economy of scale, LFG-Microturbine combined heat and power system with $CO_2$ fertilization into greenhouses was proposed and investigated including basic design process prior to the system installation at Gwang-ju metro sanitary landfill. The system features $CH_4$ enrichment for stable microturbine operation, reduction of compressor power consumption and low CO emission, and $CO_2$ supplement into greenhouse for enhancement plant growth. From many other researches, high $CO_2$ concentration was found to enhance $CO_2$ assimilation (also known as photosynthesis reaction) which converts $CO_2$ and $H_2O$ to sugar using light energy. For small scale landfills which produce LFG under $3\;m^3$/min, among currently available prime movers, microturbine is the most suitable power generation system and its low electric efficiency can be improved with heat recovery. Besides, since its exhaust gas contains very low level of harmful contaminants to plant growth such as NOx, CO and SOx, microturbine exhaust gas is a suitable and economically advantageous $CO_2$ source for $CO_2$ fertilization in greenhouse. The LFG-Microturbine combined heat and power generation system with $CO_2$ fertilization into greenhouse gas to enhance plant growth is technologically and economically feasible and improves economical feasibility compared to other small scale LFG energy project model.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.6
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• pp.468-477
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• 2014

In this research, how a solar powered HALE (high altitude long endurance) UAV (Unmanned Aerial Vehicle) can climb and reach mission altitude, 18km, starting from the ground using only solar energy. A glider type aircraft was assumed as a baseline configuration which has wing area of $35.98m^2$ and aspect ratio of 25. Configuration parameters, lift and drag coefficients were calculated using OpenVSP and XFLR5 that are NASA open source programs, and climb flights were predicted through energy balance between available energy from solar power and energy necessary for a climb flight. Minimum time climb flight was obtained by minimizing flight velocities at each altitude and total time and total energy consumption to reach the mission altitude were predicted for different take off time. Also, aircraft moving distances due to westerly wind and flight speed were calculated.

• Journal of KIISE:Information Networking
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• v.33 no.2
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• pp.165-174
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• 2006

Data dissemination using either flooding or legacy ad-hoc routing protocol is not realistic approach in the wireless sensor networks, which are composed of sensor nodes with very weak computing power, small memory and limited battery. In this paper, we propose the ELF(Energy-efficient Localized Flooding) protocol. The ELF is energy-efficient data dissemination protocol for wireless sensor networks. In the ELF protocol, there are two data delivery phases between fixed source and mobile sink node. The first phase, before the tracking zone, sensing data are forwarded by unicasting. After that, within the tracking zone, sensing data are delivered by localized flooding. Namely, the ELF Properly combines advantages from both unicasting and flooding. According to evaluation results by simulation, the proposed ELF protocol maintains very high data delivery ratio with using a little energy. Also, the property of average delay is better than others. From our research results, the ELF is very effective data dissemination protocol for wireless sensor networks.

• 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.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.913-916
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• 2010

Wireless sensor networks consist of small battery powered devices with limited energy resources. Once deployed, the small sensor nodes are usually inaccessible to the user, and thus replacement of the energy source is not feasible. Hence, energy efficiency is a key design issue that needs to be enhanced in order to improve the life span of the network. In BCDCP, all sensors send data from CH (Cluster Head) and then to BS (Base Station). BCDCP works well in small-scale network but in large scale network it is not appropriated since it uses much energy for long distance wireless communication. We propose a routing protocol - Triangular Clustering Routing Protocol (TCRP) - to prolong network life time through the balanced energy consumption. TCRP selects cluster head of triangular shape. The sensor field is divided into energy level and in every level we choose one node as a gate node. This gate node collects data and sends it to the leader node. Finally the leader node sends the aggregated data to the BS. We show TCRP outperforms BCDCP with several experiments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.6
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• pp.2606-2626
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• 2016

This article investigates the distributed data storage problem in the space information network (SIN) using distributed fountain codes. Since space nodes in the SIN are resource-limited, in order to reduce energy consumption while improving the storage reliability, an efficient distributed storage based on fountain codes and probabilistic broadcasting (DSFPB) strategy is proposed. In the proposed strategy, source packets are disseminated among the entire network according to probabilistic broadcasting (PBcast), and the final degree distribution is close to the desired robust soliton distribution (RSD), this is benefited from the appropriate packets encoding procedure of the proposed strategy. As presented by the analysis and simulations, the total cost of data dissemination is greatly reduced compared with existing representative strategies, while improving the decoding performance.

• Microbiology and Biotechnology Letters
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• v.25 no.1
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• pp.75-81
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• 1997

Streptomyces chibaensis J-59 did not grow in the culture medium containing only xylose or xylan as a carbon source, because it was defective in xylulokinase production; xylB mutant. S. chibaensis J-59 was able to produce xylanase and $\beta $-xylosidase as well as glucose isomerase. The glucose isomerase in S. chilbaensis J-59 was induced in the medium containing xylan or xylose which could be utilized as an inducer but not sa carbon and energy sources. So we tried to produce glucose isomerase whthout consumption of xylose or xylan as an inducer by using xylB mutant S. chilbaensis J-59. The optimum condition for the production of the glucose isomerase was attained in a culture medium composed of 1% xylan, 0.15% glucose, 1.5% corn steep liquor, 0.1% MaSO$_{4}$ $\CDOT $7H$_{2}$O, and 0.012% CoCL$_{2}$ $\CDOT $ 6H$_{2}$O(pH 7.0). The production of the enzyme reached to a maximum level when the bacteria were cultured for 42 h at 30$\circ $C. The enzyme production in a jar fermentor was increased twice as much as that in a flask culture.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.106-111
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• 2005

In nuclear power plant, the source of the energy is generated from the nuclear fuel rod. Given a certain level of consumption, the burnt fuel rod should be removed and replaced by a new(fresh) one. The burnt fuel is approximately one third of the whole fuel rods. Currently, this operation is done manually using paper documents and verbal communication and consumes a lot of operation time. In this study, we develop an computerized operation process of nuclear fuel rod replacement procedure based on the ERP(Enterprise Resource planning) methodology.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1013-1025
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• 1993

Agriculture in Swaziland is the most important sector of the economy from the stand point of export earning, rural employment and dependency for family food. But, inspite of 65.5 percent of the household being busy in food production for family consumption in Swaziland, the import bill of food and live animals is rising from E119.7268 million in 1987/90 (An.St.Bul.1988) . A typical farm size, based on holding's growing crops, is only 1.93 ha which may prohibit owning a four wheel tractor for farm operations. The traditional hand tools are just not efficient and comfortable to operate in order to exploit full potential of the land. There are over 120.000 draught animals which have potential to be utilized in farming. The two wheel-tractor is another energy source which can be used for many farm-operations.

• Environmental and Resource Economics Review
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• v.10 no.3
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• pp.367-386
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• 2001

In this paper we analyze the environmental advantages of district heating system. We construct three econometric models to analyze the energy consumption and economic cost as well as the emission of the major pollutants like $SO_x$, $NO_x$, DUST, and $CO_2$. As the size of heating supply is larger, the district heating system is evaluated to be better than other heating systems environmentally and costly in the long run. Especially, the district heating reduces $SO_x$ emission significantly when the size of heat production is large. But the advantages of district heating system are very sensitive to the fuel mix and heat source.