• 한국연소학회지
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• 제18권1호
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• pp.27-33
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• 2013

Hydrogen-dimethy ether(DME) partially premixed compression ignition(PCCI) engine combustion was investigated in a single cylinder compression ignition engine. Hydrogen and DME were used as low carbon alternative fuels to reduce green house gases and pollutant. Hydrogen was injected at the intake manifold with an injection pressure of 0.5 MPa at fixed injection timing, $-210^{\circ}CA$ aTDC. DME was injected directly into the cylinder through the common-rail injection system at injection pressure of 30 MPa. DME inejction timing was varied to find the optimum PCCI combustion to reduce CO, HC and NOx emissions. When DME was injected early, CO and HC emissions were high while NOx emission was low. As the DME injection was retarded, the CO and HC emissions were decreased due to high combustion efficiency. NOx emissions were increased due to the high in-cylinder temperature. When DME were injected at $-30^{\circ}CA$ aTDC, reduction of HC, CO and NOx emissions was possible with high value of IMEP.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2019년도 추계학술발표대회
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• pp.585-588
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• 2019

Predictions of Energy Consumption for Industries gain an important place in energy management and control system, as there are dynamic and seasonal changes in the demand and supply of energy. This paper presents and discusses the predictive models for energy consumption of the steel industry. Data used includes lagging and leading current reactive power, lagging and leading current power factor, carbon dioxide (tCO2) emission and load type. In the test set, four statistical models are trained and evaluated: (a) Linear regression (LR), (b) Support Vector Machine with radial kernel (SVM RBF), (c) Gradient Boosting Machine (GBM), (d) random forest (RF). Root Mean Squared Error (RMSE), Mean Absolute Error (MAE) and Mean Absolute Percentage Error (MAPE) are used to measure the prediction efficiency of regression designs. When using all the predictors, the best model RF can provide RMSE value 7.33 in the test set.

• 한국의류학회지
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• 제44권5호
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• pp.984-1003
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• 2020

The global fashion industry produces significant carbon emission and micro-plastics in oceans. Studies on sustainable design methods as such environmental issues in fashion are becoming intensely problematic. This study conducted a case study on 100 upcycle fashion brands to propose strategical upcycle fashion designs to compete in a sustainable fashion market. A literature review indicated that 3 types of textile wastes are generated as upcycling materials: post-producer, pre-consumer and post-consumer. Wastes are categorized together with 3 types of techniques: redesigning, reconstruction and handcrafting. This research derived 7 types of upcycle fashion designs that have the following features: to make luxury upcycle fashion products, to make sustainable grunge looks, to re-evaluate deadstocks, to recover vintage clothes, to convert waste into craft-arts, to offer solutions for damaged products, and to make zero-waste small fabric waste. The study results show that key drivers in the upcycle fashion design are the redesignability of materials and technique-related costs. This study implies that adopting appropriate design features can be a useful strategy for designers. New technologies will solve current problems and encourage them to design products in a new circular value system.

• 한국산림과학회지
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• 제96권3호
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• pp.235-244
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• 2007

본 연구는 교토의정서에서 인정하고 있는 조림 CDM을 북한 지역에 적용하였을 때의 경제적 타당성을 분석하였다. 기존의 북한 산림면적 추정에 관한 연구결과를 활용하여 조림 CDM을 적용할 수 있는 잠정 대상 면적을 추정한 결과 북한에는 조림 CDM 사업이 가능한 황폐임지가 약 51만 ha가 존재하는 것으로 추정되었으며, 경제적 타당성 검토 대상지로 선정된 개성지역에는 약 8,000 ha의 CDM조림사업이 기능한 황폐임지가 존재하는 것으로 나타났다. 개성지역의 산림황폐지에 북한의 주요조림수종 가운데 하나인 아까시나무(Robinia pseudoacacia)를 인공조림하고 20년 동안 유지함으로써 기존의 토지이용에 비하여 탄소고정을 증가시키는 사업을 조림 CDM사업으로 설정하였다. 수목의 탄소흡수량을 추정하고 사업을 시행하는데 필요한 산림조성 비용, 사전행정비용, 배출권 관련 행정비용을 포함하는 비용을 분석함으로써 조림 CDM사업의 경제적 효과성을 평가하였다. 개성지역 황폐임지에 아까시나무를 조림하여 20년 동안 유지하는 CDM 사업을 통해서 흡수할 수 있는 이산화 탄소량은 ha당 약 $376\;tCO_2$로 추정되었으며 배출권 판매 시나리오별로 생산할 수 있는 배출권량은 총 사업기간을 통해 tCER이 503 tCER/ha, lCER이 265 lCER/ha로 나타났다. 총 투입된 비용을 기준으로 tCER 한 단위를 생산하는 데 투입된 비용은 US$ 4.04로 나타났고 lCER 한 단위를 생산하는 데는 US$ 7.67로 나타났다. 그러나 tCER과 lCER은 시장 가격이 다를 수 있기 때문에 단순히 배출권량만으로 그 경제적 수익성에 있어서의 우위를 가름하기는 힘들다.

• Ocean and Polar Research
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• 제29권2호
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• pp.87-99
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• 2007

This study was conducted to understand the source and behavior of organic matter using the fluorescent technique (excitation-emission matrix) as a part of environmental monitoring program in the Korea manganese nodule mining site in the Northeastern Pacific Ocean. Water samples were collected at $0^{\circ},\;6^{\circ}N$, and $10.5^{\circ}N$ along $131.5^{\circ}W$ in August 2005. The concentration of total organic carbon (TOC) ranged from 58.01 to $171.93\;{\mu}M-C$. The vertical distribution of TOC was characterized as higher in the surface layer and decreased with depth. At $6^{\circ}N$, depth-integrated (from surface to 200 m depth) TOC was $337.1\;gC/m^2$, which was 1.4 times higher value than other stations. The exponential decay curve fit of vertical profile of TOC indicated that 59% of organic carbon produced by primary production in the surface layer could be decomposed by bacteria in the water column. Dissolved organic matter is generally classified into two distinctive groups based on their fluorescence characteristics using three-dimensional excitation/emission (Ex/Em) fluorescence mapping technique. One is known as biomacromolecule (BM; protein-like substance; showing max. at Ex 280/Em 330), mainly originated from biological metabolism. The other is geomacromolecule (GM; humic-like substance; showing max. at Ex 330/Em 430), mainly originated from microbial degradation processes. The concentration of BM and GM was from 0.42 to 7.29 TU (tryptophan unit) and from 0.06 to 1.81 QSU (quinine sulfate unit), respectively. The vertical distribution of BM was similar to that of TOC as high in the surface and decreased with depth. However, the vertical distribution of GM showed the reverse pattern of that of BM. From these results, it appeared that BM occupied a major part of TOC and was rapidly consumed by bacteria in the surface layer. GM was mainly transformed from BM by microbial processes and was a dominant component of TOC in the deep-sea layer.

• 에너지공학
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• 제24권4호
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• pp.89-96
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• 2015

최근 화력발전 보일러의 운전에 있어서 저등급 석탄의 성분 중 ash의 영향으로 보일러 후단부에서 생성되는 slagging/fouling 문제가 많이 보고 되고 원인 규명 및 해결책을 위한 많은 연구가 진행되고 있다. 환경적 측면에서도 NOx등 환경적인 문제를 발생시키는 부분에 대해 규제를 가하고 있는 상황이다. 이런 문제점을 해결하기 위한 방법 중 하나인 석탄의 ash를 제거한 AFC(Ash Free Coal)을 활용한 연구가 진행되고 있다. AFC는 저등급탄의 발열량을 높여 기존의 고등급탄을 보완하고 slagging/fouling 문제 및 배출가스의 오염성분을 줄일 수 있는 장점이 있다. 따라서 본 연구에서는, DTF를 이용하여 KCH 원탄과 원탄에서 추출된 무회분탄1, 무회분탄2, 잔탄, Glencore, Glencore과 잔탄을 85:15 비율로 한 혼탄을 이용하여 미연분, NOx 배출특성의 변화와 회 점착 특성을 확인하였다. 그 결과 무회분탄은 원탄과 잔탄에 비해 NOx 배출량이 현저히 낮고, 잔탄은 원탄에 비해 고등급화 되면서 반응성이 훨씬 좋아짐을 확인 하였다. 잔탄과 혼탄의 경우 일반적인 저열량탄 수준보다 낮은 점착성을 나타내는 것을 확인 하였다.

• 자원리싸이클링
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• 제33권2호
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• pp.62-72
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• 2024

기후 위기에 대응하고자 지난 2015년 파리협정에서 지구 온도상승을 2℃보다 아래로 유지하고 나아가 1.5℃ 아래로 억제하기 위한 목표를 설정하였음에도 불구하고, 지구 온도는 계속 상승 중에 있다. 실질적으로 이에 대응하기 위한 주요 전략으로 선진국들은 순환경제 실현을 제시하고 있으며, 세부 이행 방법으로는 재사용, 재제조, 재활용, 에너지 회수 등이 있다. 그중 재제조는 다른 자원순환 방법보다도 고부가가치 및 탄소중립 달성에 큰 잠재력을 가지고 있지만, 재제조를 통한 온실가스 저감효과를 정량적으로 평가할 수 있는 표준화된 방법이 부재한 상황이다. 이에 본 연구에서는 재제조에 의한 온실가스배출 감축효과 산정에 관한 2020년 이후의 최근 연구동향과 온실가스를 포함한 환경영향 평가 국제 표준 및 환경성적표지제도를 비교·분석함으로써 재제조품의 온실가스배출 저감효과 산정 표준화를 위한 핵심 요소를 도출하였다.

• 한국환경농학회지
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• 제29권4호
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• pp.362-366
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• 2010

Carbon isotope ratio ($^{13}C/^{12}C$, expressed as ${\delta}^{13}C$) of tree ring can be proxy of atmospheric $CO_2$ concentration ([$CO_2$]) due to the inter-correlation between atmospheric [$CO_2$], ${\delta}^{13}C$ of atmospheric $CO_2$, and ${\delta}^{13}C$ of plant tissue that assimilates atmospheric $CO_2$. This study was conducted to investigate if ${\delta}^{13}C$ of tree ring of Pinus densiflora in polluted area may show a lower value than that in unpolluted area and to explore the possibility of reconstructing atmospheric [$CO_2$] using its relationship with ${\delta}^{13}C$ of tree ring. During the period between 1999 and 2005, ${\delta}^{13}C$ of tree annual ring tended to decrease over time, and the ${\delta}^{13}C$ in polluted area (-27.2‰ in 2009 to -28.3‰ in 2005) was significantly (P<0.001) lower than that (-26.0‰ in 1999 to -27.1‰ in 2005) in unpolluted area. This reflects a greater emission of $CO_2$ depleted in $^{13}C$ in the polluted area. Atmospheric [$CO_2$] was significantly (P<0.01) correlated with ${\delta}^{13}C$ of tree ring in a linear fashion. Using the linear regression equation, atmospheric [$CO_2$] in the polluted area was estimated to range from 392.3 ppm in 1999 to 410.9 ppm in 2005, and these values were consistently higher than the national atmospheric [$CO_2$] monitored at the Anmyoundo meteorological station (from 370.7 ppm in 1999 to 387.2 ppm in 2005). Our study suggested that it is possible to reconstruct atmospheric [$CO_2$] in a certain area using the relationship between tree ring ${\delta}^{13}C$ and atmospheric [$CO_2$].

• Korean Chemical Engineering Research
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• 제44권6호
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• pp.631-635
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• 2006

석탄의 수소가스화 반응에 따른 합성천연가스(substitute natural gas, SNG) 제조 특성을 고찰하기 위하여 연속식 lab-scale 분류층 수소가스화기(지름 : 0.025 m, 높이 : 1.0 m)를 이용하였다. 수소가스화 시스템은 고압 가스 주입부, 석탄 주입시스템, 분류층 수소가스화 반응기, 미반응물 분리장치로 이루어졌다. 실험은 반응온도 $600{\sim}800^{\circ}C$, 수소/석탄비 0.2~0.4, 석탄주입량 0.8~2.5 g/min의 범위에서 수행되었다. 6종류의 석탄시료를 사용한 실험결과로부터 반응온도가 증가하면 메탄화에 의한 탄소 전환율은 증가하였지만 증가하는 경향은 석탄의 종류에 따라서 각각 다르게 나타났다. 또한 수소/석탄비가 증가할수록 탄소 전환율이 증가하는 반면, 메탄농도는 감소함을 보였다. 석탄 시료 중에 포함된 탄소함량이 증가할수록 탄소 전환율이 증가하였으며, 석탄중 휘발분 함량이 35 wt％일 때 최대의 탄소전환율을 얻을 수 있었다.

• 설비공학논문집
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• 제21권8호
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• pp.439-447
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• 2009

Cogeneration system produces power as well as heat recovered from waste heat during power generation process. This system has higher energy efficiency than that of the power plant. In this study the optimal design for the cogeneration system with the increase of the capacity considering life cycle cost(LCC) analysis has been performed in the general facilities such as hotels and hospitals under the assumption of electricity cost of 95 won/kWh, the initial cost of cogeneration system of 1,500,000 won!kW and the value of 0.5${\sim}$1.0 in the ratio of heat to power. The optimal ratio of cogeneration capacity divided by average electricity load of facility was found out more than 0.5 in case of electricity cost with the increase of>30%, and the percentage of $CO_2$ reduction was about 9%. The most important factors in the economic analysis of cogeneration system was found out the electrity cost and the initial cost of cogeneration system. Also the ratio of heat to power at the value of>0.5 was not affected in the economy of cogeneration system, but was very important in the $CO_2$ reduction.