• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.5
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• pp.81-88
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• 2015

바이오매스는 유망한 신재생 에너지이다. 바이오매스는 액체 및 기체 연료로 전 환 할 수 있고, 다양한 공정을 통해 열 및 전력을 생산시키는데 사용된다. 바이오매스 가스화 공정은 바이오매스를 일산화탄소, 이산화탄소, 수소 및 메탄으로 이루어진 합성 가스로 전환시키는 기술이다. 바이오매스를 이용한 합성 가스 생산 및 활용은 세계적으로 늘어나는 에너지 필요성을 충족시킬 수 있는 대체에너지이다. 현재, 바이오매스 가스화의 주요 원료는 목질계 우드 칩을 주로 사용하고 있지만, 일반적으로 우드칩의 경우 수분을 다량 함유하고 있기 때문에 가스화 공정을 위해서는 별도의 건조처리를 필요로 한다. 우드칩의 건조에는 많은 에너지가 소요되고, 다량의 우드칩 건조에는 시간과 기상 및 공간적인 환경에 영향을 받는다. 본 연구에서는 미건조 우드칩의 가스화 공정을 위하여 미건조 우드칩에 숯을 각각 10, 30, 50 % 비율로 혼합하여 실험을 수행하였고, 실험결과 생산된 합성가스의 CO 농도 는 숯의 비율에 따라 14.9 ~ 25.6 % 증가되는 경향을 나타내었지만, 반대로 $CO_2$ 및 $CH_4$ 농도는 감소하였다. 이에 따라 합성가스 생산을 위한 미건조 우드칩과 숯의 최적혼합비율은 약 30 %로 판단되며, 발열량은 $1285.7kcal/Nm^3$, Gas yield는 $2.3Nm^3/kg$ 로 나타났다. 이에 적절한 숯의 혼합사용은 미건조 우드칩의 직접적인 가스화에 도움이 될 것으로 사료되며, 바이오매스 건조 공정에 필요한 에너지를 절약할 수 있을 것으로 판단된다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.74.2-74.2
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• 2011

석탄가스화 기술은 고온, 고압 조건에서 석탄과 산소의 불완전연소 및 가스화 반응을 통해 일산화탄소(CO)와 수소($H_2$)가 주성분인 합성가스를 제조하여 이용하는 현실적인 에너지원의 확보를 위한 방법인 동시에 이산화탄소를 저감할 수 있는 기술이다. 석탄가스화기 공급되는 석탄은 산소와의 부분 산화, 수증기 및 $CO_2$와의 반응에 의하여 합성가스로 전환되는데, 일반적으로 슬래깅 방식 석탄가스화기의 정상운전 중에 가스화기 내부 온도는 $1,400{\sim}1,600^{\circ}C$ 정도의 고온이며, 운전압력은 20~60 기압으로 매우 고압 상태에서 운전이 이루어지는데, 공급되는 석탄 시료의 성분들 중 가연성 물질의 99% 이상이 합성가스로 전환되는 반면, 회분에 해당되는 무기물의 대부분은 용융 슬랙 형태로 가스화기의 벽을 타고 흘러내리다가 슬랙탭을 통해 하부의 냉각조로 떨어지면서 급냉이 이루어지게 된다. 그러므로, 석탄가스화기 정상운전중 슬랙탭 주변의 온도를 고온으로 유지함으로써 용융슬랙의 고형화를 방지하는 것은 석탄가스화기의 안정적인 연속운전을 위하여 중요한 기술 중의 하나라고 할 수 있다. 따라서, 본 연구에서는 저급탄 가스화를 위한 1 톤/일급 고온, 고압 습식 석탄가스화기의 정상운전중 슬랙탭 부근에서 용융슬랙의 고형화를 방지하기 위한 슬랙탭 버너시스템의 설계를 진행하였으며, 안정적인 운전조건 도출을 위하여 보조연료(CNG)와 산소의 공급비율에 따른 화염특성 시험을 진행하였다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.199-206
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• 2018

Due to the advantages of less raw materials and fossil fuel consumption, lower carbon footprint, and the capability of pavement performance improvement, the recycling technology of asphalt is developed and applied for road rehabilitation and construction in the western countries over the past two decades. Cold recycled asphalt mixtures are bituminous materials normally made by mixing recycled aggregate from wasted asphalt with an asphalt emulsion and water at room temperature. This paper aims at investigating the properties of cold recycled asphalt mixture with alkali-activated filler according to wasted asphalt aggregate content. As a result, as the content of wasted asphalt aggregate increased, the marshall stability of cold recycled asphalt mixture decreased and void ratio increased. Also, grading curves for cold recycled asphalt mixture as specified in GR criteria were satisfied in all aggregate mixing conditions regardless of the wasted asphalt aggregate content.

• Journal of the Economic Geographical Society of Korea
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• v.16 no.4
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• pp.647-669
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• 2013

Depletion of fossil fuels and sharp rise of international oil price as well as climate worming and frequent environmental disasters have required to strengthen resource(esp. energy) and environmental policy and discourse. And hence highly influential discourses and policies such as the concept of sustainable development and strategy for carbon regulation have been developed and pursued world-widely. But these concept and strategy have seemed to be subsumed in the process of neoliberalism, so as to have little effective results. This leads us to energy transition and energy autonomy or autarky as alternative strategic and normative concepts. Daegu has shown strong interests in urban energy problems relatively earlier than other cities, and developed the so-call 'Solar City' project. But it could not properly tackled with the problems, while tending to meet with the global imperatives. This paper considers urban energy problems and energy policy of Daegu with its significance and limitations, and suggests 4 principles for urban energy transition and autonomy with some concrete alternative measures; that is, the transition from fossil and nuclear energy to renewable energy, the transition from supply-led policy to demand side focusing policy, the transition from central governing energy system to locally distributed one, and the transition from market-dependent management to citizen-participatory energy governance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.2
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• pp.99-105
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• 1991

This study was carried out to provide basic data to be necessary for the selection of an energy recovery process based on the characteristics of municipal solid wastes(MSW). The samples were collected at Kangdong-Ku in Seoul and conducted ultimate and proximate analyses. Laboratory scale anaerobic digesters were operated to determine the non biodegradable fractions of the wastes. The results indicated that carbon and hydrogen contents, and lower heating values could be calculated from the volatile contents of MSW by the following equations : C = 0.57 VS, H =0.084 VS, and HL=49.5 VS-(6-0.045VS) W. Nonbiodegradable fractions were respectively 58.9% of volatile matters and 77.7% of MSW. Incineration and refuse derived fuel(RDF) processes appeared to be the most efficient processes in terms of weight reduction and energy recovery, But determining the energy recovery processes, the fluctuations of heating values of MSW throughout a year and available landfill site and secondary pollution should be considered.

• Korean Journal of Materials Research
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• v.19 no.12
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• pp.667-673
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• 2009

The electrocatalytic characteristics of oxygen reduction reaction of the $PtxM_{(1-x)}$ (M = Co, Cu, Ni) supported on multi-walled carbon nanotubes (MWNTs) have been evaluated in a Polymer Electrolyte Membrane Fuel Cell (PEMFC). The $Pt_xM_{(1-x)}$/MWNTs catalysts with a Pt : M atomic ratio of about 3 : 1 were synthesized and applied to the cathode of PEMFC. The crystalline structure and morphology images of the $Pt_xM_{(1-x)}$ particles were characterized by X-ray diffraction and transmission electron microscopy, respectively. The results showed that the crystalline structure of the Pt alloy particles in Pt/MWNTs and $Pt_xM_{(1-x)}$/MWNTs catalysts are seen as FCC, and synthesized $Pt_xM_{(1-x)}$ crystals have lattice parameters smaller than the pure Pt crystal. According to the electrochemical surface area (ESA) calculated with cyclic voltammetry analysis, $Pt_{0.77}Co_{0.23}$/MWNTs catalyst has higher ESA than the other catalysts. The evaluation of a unit cell test using Pt/MWNTs or $Pt_xM_{(1-x)}$/MWNTs as the cathode catalysts demonstrated higher cell performance than did a commercial Pt/C catalyst. Among the MWNTs-supported Pt and $Pt_xM_{(1-x)}$ (M = Co, Cu, Ni) catalysts, the $Pt_{0.77}Co_{0.23}$/MWNTs shows the highest performance with the cathode catalyst of PEMFC because they had the largest ESA.

• Journal of Hydrogen and New Energy
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• v.30 no.6
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• pp.531-539
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• 2019

The development of cost-effective electrocatalysts with high durability is one of the most important challenges for the commercialization of polymer electrolyte fuel cells (PEFCs). The durability of the electrocatalyst has been studied in terms of structural change in the active metal and the support. In particular, in fuel cell vehicles, degradation of the carbon-based support is known to have a significant effect on the electrocatalyst deterioration since the start-up/shut-down cycle is frequently repeated. The requirements for the support of the electrocatalyst include high surface area, electrical conductivity, chemical stability, and so on. In this study, we propose the evaluation methods for choosing better support materials and present the physicochemical properties that promising carbon supports should have. Three kinds of carbon materials with different crystallinity are compared. From in-depth study using X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, and accelerated stress test, it is clearly confirmed that the durability of carbon-supported electrocatalysts is closely related to the physicochemical properties of the carbon supports.

• Journal of the Korean Ceramic Society
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• v.40 no.3
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• pp.241-248
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• 2003

We controlled the amount of Y$_2$O$_3$additives, 8 mol% and 10 mol%, and the type of carbon pore former, activated carbon and carbon black, to improve the strength of porous NiO-YSZ anode materials for solid oxide fuel ceil. The 3-point flexural strength, porosity and electrical conductivity were evaluated. As a result, the strength of anode materials with the addition of carbon black was markedly improved. The strength of NiO-10 mol%YSZ sintered at relatively higher temperature was higher than that of NiO-8 mol%YSZ materials. The electrical conductivity of NiO-10 mol%YSZ with carbon black was evaluated as much as 10$^2$∼10$^3$S/cm at 700$^{\circ}C$∼1000$^{\circ}C$ in reducing atmosphere.

• Journal of Navigation and Port Research
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• v.39 no.4
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• pp.361-370
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• 2015

Wind energy began to receive attention as a new alternative fuel since 20 years ago and is growing as a booming global business model. Global wind power generation in the world has been continuously increasing for the past 10 years, accounting for over 30% of cumulative rate compared to total power generation. Global demand for wind power generation is gradually expanding due to restriction on carbon emission and environmental problems caused by increased greenhouse effect. Accordingly in this study, current transportation routes are classified into three types including access-priority route, economics-priority route, and convenience- priority route depending on distribution characteristics of wind power equipment in order to suggest transportation methods other than ships. The three types of transportation route that this study declared can make the Wind power equipment manufacturing companies can judge not only the duration of transportation but also effectiveness and economic feasibility. It means that the manufacturers can analyze and compare the effectiveness and economic feasibility, which are proceed by the shipping company and freight forwarder until now days.

• Journal of Navigation and Port Research
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• v.35 no.5
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• pp.387-392
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• 2011

The value of Photovoltaic as an independent power supply is small, but the city's carbon emissions reduction and for the reduction of fossil fuel use distributed power is the power source to a very high value. However, according to the weather conditions for solar power generation by power fluctuations because of the size distribution to be effective, the big swing for effectively controlling real-time monitoring should be made. But that depends on solar power generation solar radiation forecasts from the National Weather Service does not need to predict it, and this study, the diffuse sky radiation in the history of the solar radiation in the darkness of the clouds, thick and weather forecasts can be inferred from the atmospheric transmittance to announce this value is calculated to represent each weather forecast solar radiation and solar radiation predicted by substituting the expression And the measured solar radiation and CRM (Cloud Cover Radiation Model) technique with an expression of Kasten and Czeplak irradiation when compared to the calculated predictions were verified.