• 자원리싸이클링
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• 제29권5호
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• pp.64-72
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• 2020

시멘트 산업의 질소산화물 배출량 감축을 위해 소성로에 다단연소공정을 적용할 경우, 질소산화물을 질소로 환원시키고 미연소 물질을 완전히 연소시켜 연소효율을 증대할 수 있는 산화/환원 구간이 필수적이다. 이에 본 연구에서는 시멘트 소성로 calciner에 산화/환원 구간 설정 시 최종 생산품인 시멘트 클링커의 품질안정성을 확보할 수 있는 최적 산화/환원 소성분위기를 거시적으로 관찰하고자 하였으며, 소성조건에 따른 원료물질의 질량변화, 탈탄산률, 소성완료율 등을 조사하였다. 실험결과, 대체로 환원분위기보다 산화분위기에서 원료물질의 열분해가 촉진되는 경향을 나타내며, 원료물질 자체 성분특성에 따라 비교적 CaO 함량이 높은 석회석의 열분해가 시멘트 조합원료보다 늦게 진행되는 것을 알 수 있었는데 이는 소성로 내 CO₂ 분압에 의한 현상으로 생각된다. 산화/환원 소성분위기에 따른 원료물질의 열분해 특성은 일반적인 석회석 열분해 온도보다 낮은 온도범위에서 비교적 큰 차이를 보였는데, 소성온도 750℃ 구간에 산화분위기 형성에 따라 원료물질의 열효율 향상을 기대할 수 있을 것으로 생각된다. 다만, 본 연구의 경우 실험실 규모의 연구로서 현장공정과는 차이가 있기 때문에, pilot plant 규모의 실검증결과가 필요한 것으로 판단된다.

• Journal of Pharmaceutical Investigation
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• 제40권3호
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• pp.139-153
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• 2010

Nitrosative stress is defined as pathophysiological conditions that are related to covalent modifications of proteins by nitration/nitrosylation by forms of nitrogen oxide ($NO_x$), leading to DNA damage, ultimately, cell death. This type of stress condition appears to be associated with a number of disease states, including diabetes, inflammation and neurodegenerative diseases. Since these pathological conditions are frequently chronic in nature and, thus, require long-term treatment, changes in pharmacokinetics are likely to affect the therapy. Transporters are membrane proteins that facilitate the movement of substrates, including drugs, across plasma membranes of epithelial / endothelial cells. Since it is now increasingly evident that transporters are pharmacokinetically significant, functional alteration of transporters by this stress condition may have therapeutic relevance. In this review, experimental techniques that are used to study both in vivo and in vitro nitrosative stress are summarized and discussed, along with available literature information on the functional implication of transporters under conditions of nitrosative stress conditions. In the literature, both functional induction and impa irment were apparently present for both drug transporter families [i.e., ATP-binding cassette (ABC) and solute carrier families (SLC)]. Furthermore, a change in the function of a certain transporter appears to have temporal dependency by impairment in the early phase of nitrosative stress and induction thereafter, suggesting that the role of nitrosative stress is complex in terms of functional implications of the transporters. Although the underlying mechanisms for these alterations are not fully understood, protein nitration/nitrosylation appears to be involved in the functional impairment whereas transcript factor(s) activated by nitrosative stress may play a role, at least in part, in functional induction. Interestingly, functional induction under conditions of nitrosative stress has not been observed for SLC transporters while such impairment has been documented for both ABC and SLC transporters. Further investigations appear to be necessary to fully delineate the underlying reasons for these differences on the impact and importance of nitrosative stress conditions.

• 대한기계학회논문집B
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• 제38권12호
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• pp.1017-1026
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• 2014

Urea-SCR 머플러 시스템 입구와 촉매 전단에 설치된 다공튜브는 우레아 수용액 분무의 균일분포, SCR 촉매 활용도 증대 및 암모니아 슬립을 방지하기 위해 사용되고 있다. 다공튜브의 오리피스 면적비 변화가 머플러 챔버 내부유동 특성에 끼치는 영향이 상용 소프트웨어를 이용하여 해석적으로 조사되었다. 다공튜브 오리피스 면적비 변화는 촉매 전단에 설치된 챔버 내부의 벌크 선회유동 형성과 촉매 전단 속도분포의 균일도 지수에 큰 영향을 끼침을 보였다. 해석결과를 검증하기 위해 엔진실험이 ESC 및 ETC 모드에서 수행되었다. 엔진 실험결과 다공튜브 길이방향으로 보다 많은 유량이 흐르는 모델이 가장 높은 NOx 저감 효율을 나타냈으며, 이것은 높은 균일도지수 및 강한 선회유동을 나타내는 해석 결과와 일치됨을 알 수 있었다.

• 청정기술
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• 제28권2호
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• pp.131-137
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• 2022

현재 반도체 공정에서 다양한 by-product 및 미사용 가스가 배출되고 있다. 오염물질을 함유한 배기는 일반적으로 유기, 산, 알칼리, 열, 캐비넷 배기 등으로 분류하며, 각각의 배기 특성에 맞는 대기 방지설비에서 처리 후 배출된다. 유기 배기 물질로서 휘발성 유기 화합물(volatile organic compound, VOC)은 산소 함유 탄화수소, 유황 함유 계 탄화수소 및 휘발성 탄화수소를 총칭하는 물질이고, 알칼리 배기의 주요성분은 암모니아(NH₃), 수산화테트라메틸암모늄(Tetramethylammonium hydroxide, TMAH)등이 있다. 본 연구의 목적은 유기와 알칼리 배기가스를 동시에 처리하기 위해 직접 연소 및 로 내 온도를 일정하게 유지하여 연소 특성 파악하고 NO_X 저감률을 분석하고자 진행하였다. VOC는 Acetone, IPA(isopropyl alcohol), PGMEA(propylene glycol methyl ether acetate)을 사용하였으며, 알칼리 배기 대표 물질로는 암모니아를 사용하였다. 실험 변수로는 온도와 당량 비(equivalence ratio, ER)로 배기가스 특성을 살펴보았다. 물질별 단독 및 혼합 연소테스트를 진행하였다. VOC 단독 테스트 결과 당량 비 1.4 조건에서 완전 연소가 일어남을 확인하였다. 암모니아는 당량 비 감소에 따라 산소 및 질소산화물의 농도가 감소하였다. 혼합 연소 운전 결과 배기가스 조성 내 질소산화물의 대부분은 일산화질소였으며 이산화질소는 10 ppm 부근으로 검출되었다. 전체적으로 질소산화물의 농도는 반응온도가 증가하면서 산화반응이 활성화되어 감소하는 경향을 나타나지만 이산화탄소의 농도는 증가하는 경향을 확인하였다. 전기열원을 적용한 무 화염 연소 기술을 적용하였을 때 VOC 및 암모니아 연소가 원활하게 일어남으로써 현재 별도로 운전되는 유기 및 알칼리 배기 시스템보다 경제성 및 공간적인 측면에서 장점이 있다고 판단된다.

• Asian-Australasian Journal of Animal Sciences
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• 제28권1호
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• pp.102-110
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• 2015

The purpose of this experiment was to determine and compare the digestibility of crude protein (CP) and amino acids (AA) in full-oil (no oil extracted) and de-oiled (oil extracted) corn distillers dried grains with solubles (DDGS) with different condensed distillers solubles (CDS) ratios. Six barrows ($29.6{\pm}2.3kg$) fitted with ileal T-cannula were allotted into a $6{\times}6$ Latin square design. Each period was comprised of a 5-d adaption period followed by a 2-d collection of ileal digesta. The five test diets contained 62% DDGS as the sole source of AA. A nitrogen-free diet was used to measure the basal endogenous losses of CP and AA. Chromic oxide (0.3%) was used as an index in each diet. The results showed that CP and AA were very similar in 5 DDGS, but the standardized ileal digestibility (SID) of lysine (from 56.16% to 71.15%) and tryptophan (from 54.90% to 68.38%) had the lowest values and largest variation within the essential AA, which suggests reduced availability of AA and different levels of Maillard reactions in the five DDGS. The apparent ileal digestibility and SID of CP and most of AA in full-oil DDGS (sources 1 and 2) were greater (p<0.05) than de-oiled DDGS (sources 3, 4, and 5). Comparing the AA SID in the 5 DDGS, full-oil with low CDS ratio DDGS (source 1) had non-significantly higher values (p>0.05) than full-oil with high CDS ratio DDGS (source 2); however, the SID of most AA of de-oiled with low CDS ratios DDGS (source 3) were non-significantly lower (p>0.05) than de-oiled with high CDS ratio DDGS (source 4); and the de-oiled DDGS with middle CDS ratio (source 5) but with different drying processing had the lowest SID AA values. In conclusion, de-oiled DDGS had lower SID of CP and AA than full-oil DDGS; a higher CDS ratio tended to decrease the SID of AA in full-oil DDGS but not in de-oiled DDGS; and compared with CDS ratio, processing, especially drying, may have more of an effect on AA digestibility of DDGS.

• Korean Chemical Engineering Research
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• 제59권1호
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• pp.127-137
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• 2021

미세먼지 전구체인 질소산화물(NOx)에 대한 대기배출부과금 제도가 2020년부터 국내에 도입 및 시행됨에 따라 이를 저감하기 위한 경제적인 연소기술 개발은 매우 시급한 실정이다. 본 연구에서는 해외 우드펠릿 대체재로서 REC(Renewable Energy Certificates) 확보가 가능한 국내 미이용 산림 바이오매스를 연료로 하여 0.1 MWth급 순환유동층 연소 설비에서 NOx 저감을 위한 air-staging 효과를 고찰하였다. 운전 변수로는 air-staging 적용 유무, 3차 공기 공급 높이(6.4 m, 8.1 m, 9.4 m) 그리고 air-staging 비율(1차 공기:2차 공기:3차 공기=91%:9%:0%, 82%:9%:9%, 73%:9%:18%) 변화이며 운전 변수에 대한 배기가스 내 NO와 CO 농도, 연소로 높이별 온도와 압력 프로파일, 포집된 비산재(fly ash) 내 미연탄소 함량과 연소효율을 분석하였다. 3차 공기를 가장 높은 9.4 m에서 공급한 air-staging 운전 시 NO 농도는 100.7 ppm으로 air-staging을 적용하지 않은 운전 조건(148.8 ppm)보다 32.3% 감소하지만 CO 농도는 오히려 52.2 ppm에서 99.8 ppm으로 91% 증가하였다. 더불어, NO 농도의 저감을 위한 환원영역과 CO 농도의 저감을 위한 산화영역 확보를 위해 3차 공기 공급 높이를 6.4 m로 유지하며 3차 공기 공급량을 늘리고 1차 공기 공급량을 낮춘 air-staging 운전 조건(73%:9%:18%)에서는 NO와 CO 농도가 각각 90.8 ppm과 66.1 ppm으로 air-staging 적용 조건 중 가장 감소되는 것을 확인하였다. 이러한 최적 운전 조건에서 연소효율 역시, air-staging을 적용하지 않은 운전 조건의 연소효율(98.3%) 보다 높은 99.3%임을 확인하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제25권12호
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• pp.1748-1758
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• 2012

Two experiments were conducted to evaluate the effects of chemical composition of wheat shorts and red dog on energy and amino acid digestibility in growing pigs and to establish prediction models to estimate their digestible (DE) and metabolizable (ME) energy content and as well as their standardized ileal digestible (SID) amino acid content. For Exp. 1, sixteen diets were fed to thirty-two growing pigs according to a completely randomized design during three successive periods. The basal diet was based on corn and soybean meal while the other fifteen diets contained 28.8% wheat shorts (N = 7) or red dog (N = 8), added at the expense of corn and soybean meal. Over the three periods, each diet was fed to six pigs with each diet being fed to two pigs during each period. The apparent total tract digestibility (ATTD) of energy in wheat shorts and red dog averaged 75.1 and 87.9%. The DE values of wheat shorts and red dog averaged 13.8 MJ/kg (range 13.1 to 15.0 MJ/kg) and 15.1 MJ/kg (range 13.3 to 16.6 MJ/kg) of dry matter, respectively. For Exp. 2, twelve growing pigs were allotted to two $6{\times}6$ Latin Square Designs with six periods. Ten of the diets were formulated based on 60% wheat shorts or red dog and the remaining two diets were nitrogen-free diets based on cornstarch and sucrose. Chromic oxide (0.3%) was used as an indigestible marker in all diets. There were no differences (p>0.05) in SID values for the amino acids in wheat shorts and red dog except for lysine and methionine. Apparent ileal digestibility (AID) and SID values for lysine in different sources of wheat shorts or red dog, which averaged 78.1 and 87.8%, showed more variation than either methionine or tryptophan. A stepwise regression was performed to establish DE, ME and amino acid digestibility prediction models. Data indicated that fiber content and amino acid concentrations were good indicators to predict energy values and amino acid digestibility, respectively. The present study confirms the large variation in the energy content and amino acid digestibility in wheat shorts and red dog, and describes the factors that influence this variation and presents equations based on chemical composition that could probably be used to predict the DE and ME values as well as the amino acid digestibility of wheat shorts and red dog.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.388-388
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• 2016

Chemical mist deposition (CMD) of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was investigated with cavitation frequency f, solvent, flow rate of nitrogen, substrate temperature $T_s$, and substrate dc bias $V_s$ as variables for efficient PEDOT:PSS/crystalline (c-)Si heterojunction solar cells (Fig. 1). The high-speed camera and differential mobility analysis characterizations revealed that average size and flux of PEDOT:PSS mist depend on f, solvent, and $V_s$. The size distribution of mist particles including EG/DI water cosolvent is also shown at three different $V_s$ of 0, 1.5, and 5 kV for a f of 3 MHz (Fig. 2). The size distribution of EG/DI water mist without PEDOT:PSS is also shown at the bottom. A peak maximum shifted from 300-350 to 20-30 nm with a narrow band width of ~150 nm for PEDOT:PSS solution, whose maximum number density increased significantly up to 8000/cc with increasing $V_s$. On the other hand, for EG/water cosolvent mist alone, the peak maximum was observed at a 72.3 nm with a number density of ~700/cc and a band width of ~160 nm and it decreased markedly with increasing $V_s$. These findings were not observed for PEDOT:PSS/EG/DI water mist. In addition, the Mie scattering image of PEDOT:PSS mist under white bias light was not observed at $V_s$ above 5 kV, because the average size of mist became smaller. These results imply that most of solvent is solvated in PEDOT:PSS molecule and/or solvent is vaporized. Thus, higher f and $V_s$ generate preferentially fine mist particle with a narrower band width. Film deposition occurred when $V_s$ was impressed on positive to a c-Si substrate at a Ts of $30-40^{\circ}C$, whereas no deposition of films occurred on negative, implying that negatively charged mist mainly provide the film deposition. The uniform deposition of PEDOT:PSS films occurred on textured c-Si(100) substrate by adjusting $T_s$ and $V_s$. The adhesion of CMD PEDOT:PSS to c-Si enhanced by $V_s$ conspicuously compared to that of spin-coated film. The CMD PEDOT:PSS/c-Si solar cell devices on textured c-Si(100) exhibited a ${\eta}$ of 11.0% with the better uniformity of the solar cell parameters. Furthermore, ${\eta}$ increased to 12.5% with a $J_{sc}$ of $35.6mA/cm^2$, a $V_{oc}$ of 0.53 V, and a FF of 0.67 with an antireflection (AR) coating layer of 20-nm-thick CMD molybdenum oxide $MoO_x$ (n= 2.1) using negatively charged mist of 0.1 wt% 12 Molybdo (VI) phosphoric acid n-Hydrate) $H_3(PMo_{12}O_40){\cdot}nH_2O$ in methanol. CMD. These findings suggest that the CMD with negatively charged mist has a great potential for the uniform deposition of organic and inorganic on textured c-Si substrate by adjusting $T_s$ and $V_s$.