• 한국안전학회지
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• 제17권1호
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• pp.1-5
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• 2002

An approach for the damage of delamination which is the major concern during mechanical working for composite laminate material is proposed based on linear elastic fracture mechanics. This paper presents method evaluating of damage crack length using by average thrust force with AE characteristics. Also, the relations of AE characteristics are obtained from delamination damages. We found the onset ply of the delamination and a critical energy release rate and expressed a stress intensity factor by AEcount equation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1815-1820
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• 2008

Self-catalytic behavior of combustion-synthesized carbon nanotubes (CNTs) is evaluated using a double-faced wall stagnation flow burner with a CNT-deposited stainless steel plate wall. CNT formation is observed using field-emission scanning and transmission electron microscopies and Raman spectroscopy. A self-catalytic behavior of multi-walled CNTs (MWCNTs) shows the enhanced ratio of channel diameter to tube wall thickness and the enhanced intensity ratio of G-band to D-band in Raman spectroscopy, implying that the quality of metal-catalytic, flame-synthesized MWCNTs can be much improved via a CNT self-catalytic flame-synthesis process. Thus, using a DWSF burner through the self-catalytic process has potential in mass production of CNTs having much improved quality.

• Architectural research
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• 제15권3호
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• pp.143-150
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• 2013

The Korean government recently has rediscovered the potential value of Han-Ok, the Korean traditional house, as an eco-friendly building. In order to objectively verify the environmental performance of Han-Ok as a low carbon green building, this paper suggests the analysis method of GHG emission load of Korean traditional house, based on Life Cycle Assessment, which is commonly abbreviated to "LCA". The environmental impacts caused by building construction and operation can be analyzed through the sum of input and output data from every phase. The study particularly describes the GHG reduction effect by using traditional building materials such as wood products, traditional clay roof tiles, and mud, which are mainly used to construct Han-Ok. Also the study proposes the method for comparative analysis of quantity of GHG emissions in building's entire life cycle so that the data can be used as a reliable basis to optimize the environmental performance of building.

• Spatial Information Research
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• 제20권2호
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• pp.25-34
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• 2012

대구지역은 주위가 산으로 둘러싸인 분지형 도시이기 때문에 대기 환경 쾌적성이 타 도시 보다 낮은 편이다. 따라서 본 연구에서는 대구지역 자동대기오염측정소의 위치를 일산화탄소(CO) 배출량 분포에 기초하여 CO를 체계적으로 관리하기위한 적합한 장소에 대해 조사하였다. 이를 위하여 현재 대구지역 CO 관리정책 수립에 기초자료를 제공하는 자동대기측정소의 위치 적절성에 대하여 평가하였다. 대구시 수치지도와 환경부에서 제공하는 CAPSS(대기정책지원시스템 ; Clean Air Policy Support System) 자료를 활용하여 배출량 지도를 작성하였다. 도로, 아파트, 공장, 소각장 4가지로 구분하여 배출량을 입력한 뒤 법정동별 평균 배출량을 산출하였다. CO 배출지역을 고 배출량 지역과 저 배출량 지역 10단계로 구분하고 현재 측정소가 어느 단계에 해당하는지 조사하였다. 결과적으로, 저 배출량 지역 보다는 CO 고 배출량 지역에 해당하는 측정소가 부족한 것으로 나타났다. 특히, 1999년부터 2007년까지 공통적으로 추가 설치가 필요하다고 나온 국우동 외 6곳에 CO 측정망이 설치된다면 보다 다양한 기초 자료의 제공으로 체계적인 CO 관리가 가능할 것으로 판단된다.

• 한국대기환경학회지
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• 제30권4호
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• pp.319-326
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• 2014

Exhaust gas emitted as a result of the incomplete combustion of biomass in charcoal kilns includes odor compounds as well as other air pollutants such as particulate matters, sulfur and nitrogen oxides, and carbon monoxide. A number of offensive odor compounds affect quality of life. In this study, odor emissions were investigated from biomass burning in a pilot-scale charcoal kiln and a commercial-scale kiln. Complex odor from emission source reached up to 10,000 dilutions to threshold during the study period. Combustion fume was found to contain reduced sulfur compounds, aldehydes, and volatile organic compounds. Hydrogen sulfide and methyl mercaptan were the major odorants which highly contributed to the offensive odor.

• Structural Monitoring and Maintenance
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• 제1권1호
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• pp.111-130
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• 2014

The increased use of carbon fiber reinforced polymer (CFRP) in retrofitting reinforced concrete (RC) members has led to the need to develop non-destructive techniques that can monitor and characterize the unique damage mechanisms exhibited by such structural systems. This paper presented the damage characterization results of six CFRP retrofitted RC beam specimens tested in the laboratory and monitored using acoustic emission (AE). The focus of this study was to continuously monitor the change in AE parameters and analyze them both qualitatively and quantitatively, when brittle failure modes such as debonding occur in these beams. Although deterioration of structural integrity was traceable and can be quantified by monitoring the AE data, individual failure mode characteristics could not be identified due to the complexity of the system failure modes. In all, AE was an effective non-destructive monitoring tool that can trace the failure progression in RC beams retrofitted with CFRP. It would be advantageous to isolate signals originating from the CFRP and concrete, leading to a more clear understanding of the progression of the brittle damage mechanism involved in such a structural system. For practical applications, future studies should focus on spectral analysis of AE data from broadband sensors and automated pattern recognition tools to classify and better correlate AE parameters to failure modes observed.

• 자원ㆍ환경경제연구
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• 제13권3호
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• pp.441-468
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• 2004

환경($CO_2$) 혼합형 산업연관모형을 이용하여 우리나라의 수출상품에 체화된 $CO_2$ 배출량을 추정하였다. 혼합모형은 투입되는 모든 재화의 단위금액으로 하는 전통적인 투입산출모형에서 에너지 부문의 투입을 실물단위로 바꿔주는 것이다. 추정결과 2000년의 경우 225조 3,000억 원 어치 비에너지 상품 수출로 인한 $CO_2$ 배출량은 5,188만 탄소톤으로 우리나라 전체 $CO_2$ 배출량의 44%를 차지한다. 수출상품의 $CO_2$ 배출집약도는 0.227탄소톤/백만원으로 나타났다. 현재 진행되고 있는 기후변화협약에서는 $CO_2$ 배출의 책임을 생산국 기준으로 하고 있다. 이러한 방식은 온실가스의 배출 책임이 상품 수입국에서 상품 수출국으로 전가된 것으로 볼 수 있다. 더 큰 문제는 앞으로 많은 나라들이 탄소집약적 상품 생산을 기피하고 수입에 의존하려 하게 하는 '탄소누출' 현상이다. 이 같은 문제점을 방지할 수 있는 대안은 상품 생산의 수출국보다는 소비국에도 $CO_2$ 배출의 책임을 묻는 것이다. 이는 사용자 책임원칙과 오염자부담원칙에도 부합하는 것이며, 이 원칙이 적용되면 지구온난화 방지를 위한 기후변화협약의 실효성을 높이는 역할을 할 수 있을 것이다.

• 한국항공우주학회지
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• 제44권7호
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• pp.603-610
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• 2016

본 논문에서는 석탄으로부터 생성된 합성천연가스(SNG)의 다양한 연료 조성에 대한 배기가스 배출 특성 및 희석제에 대한 NOx배출 저감에 대해 기술하였다. 예혼합거리가 짧은 부분 예혼합 가스터빈 연소기에서 SNG 연료조성에서의 수소 비율과 입열량, 당량비를 조절해 가며 연소특성을 관찰하였다. 수소 비율에 따른 NOx 배출지수는 유사하게 나타났고, 화염가시화를 통해 화염의 특성을 파악할 수 있었다. CO 배출의 경우 당량비 1 구간에서 특이점이 나타났으며, 이를 화염의 자발광 이미지와 자발광 강도를 통하여 원인을 파악할 수 있었다. 또한 높은 NOx 배출을 저감하기 위하여 질소($N_2$)와 이산화탄소($CO_2$) 희석제를 사용하여 희석제 공급량에 대한 저감 효과를 파악하였다. 이로부터 희석제의 비열과 열용량이 연소로부터 발생한 연소열을 흡수하여 열화에 의한 NOx 배출을 저감하는 효과를 확인하였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.31.1-31.1
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• 2009

Carbon nanotubes (CNTs) are attractive material because of their superior electrical, mechanical, and chemical properties. Furthermore, their geometric features such as a large aspect ratio and a small radius of curvature at tip make them ideal for low-voltage field emission devices including backlight units of liquid crystal display, lighting lamps, X-ray source, microwave amplifiers, electron microscopes, etc. In field emission devices for display applications, the phosphor anode is positioned against the CNT emitters. In most case, light generated from the phosphor by electron bombardment passes through the anode front plate to reach observers. However, light is produced in a narrow depth of the surface of the phosphor layer because phosphor particles are big as much as several micrometers, which means that it is necessary to transmit through the phosphor layer. Hence, a drop of light intensity is unavoidable during this process. In this study, we fabricated a transparent cathode back plate by depositing an ultra-thin film of single walled CNTs (SWCNTs) on an indium tin oxide (ITO)-coated glass substrate. Two types of phosphor anode plates were employed to our transparent cathode back plate: One is an ITO glass substrate with a phosphor layer and the other is a Cr-coated glass substrate with phosphor layer. For the former case, light was radiated from both the front and the back sides, where luminance on the back was ~30% higher than that on the front in our experiments. For the other case, however, light was emitted only from the cathode back side as the Cr layer on the anode glass rolled as a reflecting mirror, improving the light luminance as much as ~60% compared with that on the front of one. This study seems to be discussed about the morphologies and field emission characteristics of CNT emitters according to the experimental parameters in fabricating the lamps emitting light on the both sides or only on the cathode back side. The experimental procedures are as follows. First, a CNT aqueous solution was prepared by ultrasonically dispersing purified SWCNTs in deionized water with sodium dodecyl sulfate (SDS). A milliliter or even several tens of micro-liters of CNT solution was deposited onto a porous alumina membrane through vacuum filtration. Thereafter, the alumina membrane was solvated with the 3 M NaOH solution and the floating CNT film was easily transferred to an ITO glass substrate. It is required for CNT film to make standing CNTs up to serve as electron emitter through an adhesive roller activation.

• 대한기계학회논문집B
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• 제31권8호
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• pp.672-679
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• 2007

The combustion characteristics of a liquefied petroleum gas-di-methyl ether (LPG-DME) compression ignition engine was investigated under homogeneous charge and stratified charge conditions. LPG was used as the main fuel and injected into the combustion chamber directly. DME was used as an ignition promoter and injected into the intake port. Different LPG injection timings were tested to verify the combustion characteristics of the LPG-DME compression ignition engine. The combustion was divided into three region which are homogeneous charge, stratified charge, and diffusion flame region according to the injection timing of LPG. The hydrocarbon emission of stratified charge combustion was lower than that of homogeneous charge combustion. However, the carbon monoxide and nitrogen oxide emission of stratified charge combustion were slightly higher than those of the homogeneous charge region. The indicated mean effective pressure was reduced at stratified charge region, while it was almost same level as the homogeneous charge combustion region at diffusion combustion region. The start of combustion timing of the stratified charge combustion and diffusion combustion region were advanced compared to the homogeneous charge combustion. It attributed to the higher cetane number and mixture temperature distribution which locally stratified. However, the knock intensity was varied as the homogeneity of charge was increased.