• 한국미생물·생명공학회지
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• 제24권1호
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• pp.92-100
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• 1996

For the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(P(3HB-co-3HV)) from butyric acid and valeric acid, 10 strains of bacteria capable of producing P(3HB-co-3HV) were isolated from soil. Among them, the strain HJ-067 showed the best ability of producing P(3HB-co-3HV), and was indentified as a Azotobacter sp. For the production of P(3HB-co-3HV), the optimum concentrations of butyric and valeric acid were 3.0g/l, respectively. The most effective nitrogen source was $(NH_4)_{2}SO_4$ at an optimum concentration of 0.75g/l, which was equivalent to 21.36 in C/N ratio. Deficiency of the cationic metal ions ($Zn^{2+},\;Co^{2+},\;Mn^{2+}$) in the proguction medium had stimulating effect on P(3HB-co-3HV) accumulation, especially in the manganese. deficient medium. The optimum temperature for P(3HB-co-3HV) production was 27$^{\circ}C$ and the optimum initial pH was 7.0. Under the optimum conditions, 1.82g/l of P(3HB-co-3HV) and 3.00g/l of dry biomass were produced after 36 hour cultivation, and the P(3HB-co-3HV) yield and HV% were 60.60% (w/w), 15.92%, respectively.

• KIEAE Journal
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• 제10권4호
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• pp.101-109
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• 2010

As global warming progresses, nations around the world are trying to reduce emission of $CO_2$ that accounts for the greatest portion of greenhouse gases. To reduce $CO_2$ emission, it is first necessary to estimate $CO_2$ emission of each industry. Government authorities estimate basic unit of $CO_2$ emission from re-bar that is one of the key materials of construction industry with LCA technique (Life Cycle Assessment). However, basic unit of $CO_2$ emission varies from organization to organization. The Ministry of Land, Transport and Maritime Affairs (2004) publishes it 3.48($TCO_2/ton$) and 0.30($TCO_2/ton$) with input-output analysis while the Korea Environmental Industry & Technology Institute (2008) defines it as 0.34($TCO_2/ton$) with process analysis, which indicates ambiguity in application of basic unit of $CO_2$emission. Based on the analysis of conventional methods used for estimating the $CO_2$ emission, therefore, this research suggests existing problems on the methods and focuses on proposing an strategy to effectively estimate the basic unit of $CO_2$ emission according to the energy consumption limited to the re-bar production in steel mill in order to overcome the problems. The result of this research is expected to be helpful in calculating and reducing $CO_2$ emission.

• Korean Chemical Engineering Research
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• 제44권5호
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• pp.528-534
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• 2006

고온 플라즈마가 적용된 플라즈마트론을 이용하여 바이오가스 개질을 통해 수소를 생산하는데 있어서 최적 운전 조건에 대해 연구하였다. 음식물 쓰레기의 혐기성 발효조에서 생성된 바이오가스 구성비($CH_4/CO_2$)가 1.03, 1.28, 2.12인 바이오가스로 개질실험을 수행하고, 수소 생산과 메탄 전환율을 향상시키기 위해 바이오가스 유량비, 수증기 유량비, 입력전력 변화와 같은 변수별 연구를 수행하였다. 바이오가스 유량비(biogas/TFR : total flow rate), 수증기 유량비($H_2O/TFR$: total flow rate), 입력전력이 각각 0.32~0.37, 0.36~0.42, 8 kW일 때 메탄의 전환율이 81.3~89.6％인 최적운전조건을 보였다. 이때 합성가스 중의 수소와 일산화탄소의 농도는 27.11~40.23％, 14.31~18.61％이며, 수소 수율은 40.6~61％, 에너지 전환율은 30.5~54.4％, $H_2/CO$ 비는 1.89~2.16이다.

• Preventive Nutrition and Food Science
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• 제16권4호
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• pp.364-369
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• 2011

Levels of carbon dioxide gas, a metabolite of microbial growth, have been reported to parallel the onset of microbial spoilage and may be used as a convenient index for a packaged food's shelf life. This study aimed to establish a kinetic model of $CO_2$ production from perishable food for the potential use for shelf life control in the food supply chain. Aerobic bacterial count and package $CO_2$ concentration were measured during the storage of seasoned pork meat at four temperatures (0, 5, 10 and $15^{\circ}C$), and their interrelationship was investigated to establish a mathematical model. The microbial growth at constant temperature was described by using model of Baranyi and Roberts. $CO_2$ production from the stored food could be explained by taking care of its yield and maintenance factors linked to the microbial growth. By establishing the temperature dependence of the microbial growth and $CO_2$ yield factor, $CO_2$ partial pressure or concentration in package headspace could be estimated to a limited extent, which is helpful for controlling the shelf life under constant and dynamic temperature conditions. Application and efficacy of the model needs to be improved with further refinement in the model.

• Ocean and Polar Research
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• 제38권4호
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• pp.303-314
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• 2016

We tested the combined effects of increased partial pressure of $CO_2$ ($pCO_2$) and temperature on the reproduction and survival of the copepod Calanus sinicus from Asan Bay, the Yellow Sea under laboratory conditions to understand the impact of acidification on copepods. Egg production rate, survival rate, and fecal pellet production of C. sinicus were not affected by 1305 ppm $pCO_2$ or with combined treatments of temperature and $pCO_2$, including $8^{\circ}C$ and 289 ppm $pCO_2$ (ambient), $8^{\circ}C$ and 753 ppm $pCO_2$ (high $pCO_2$), $12^{\circ}C$ and 289 ppm $pCO_2$ (high temperature), and $12^{\circ}C$ and 753 ppm $pCO_2$ (greenhouse), for 5 or 10 d of exposure. However, egg hatching success of C. sinicus decreased significantly in the greenhouse treatment compared with the ambient or the high $pCO_2$ treatments. These results suggest that a combined treatment ($pCO_2$ and temperature) affected egg viability more than a single treatment($pCO_2$).

• 자원리싸이클링
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• 제30권6호
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• pp.12-18
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• 2021

수성가스 전환 반응은 가스화로 생성된 합성 가스에 수소 생산 증가와 H₂/CO 비율 제어를 위해 수증기를 첨가하는 가스화 후속 공정이다. 본 연구에서는 RPF(Refuse plastic fuel) 가스화 시스템의 합성가스를 대상으로 수성가스 전환 반응을 연구하였다. 수성가스 전환 반응은 촉매를 이용하여 high temperature shift(HTS) 와 low temperature shift(LTS) 반응에 대하여 lab scale 관형 반응기를 이용하여 반응 온도, steam/carbon ratio, 유량의 변화가 H₂ 생성과 CO 전환율에 미치는 영향을 조사하였다. 운전 온도는 HTS 시스템이 250-400℃, LTS 시스템이 190-220℃이며 steam/carbon ratio는 1.5-3.5로 변화시켰다. 반응 모의 가스의 농도는 RPF 합성가스의 농도를 기준으로 CO, 40vol%, H₂, 25vol%, CO₂, 25vol%이다. 반응 온도와 steam/carbon ratio가 증가함에 따라 CO 전환율 및 H₂ 생성량이 증가하고, 유량이 증가하면 촉매층의 체류시간 단축으로 CO 전환율과 H₂ 생성량이 감소하였다.

• Journal of Plant Biotechnology
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• 제33권4호
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• pp.249-255
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• 2006

Effects of ethylene inhibitors like silver nitrate $(AgNO_3)$, cobalt chloride $(CoCl_2)$ and Salicylic acid (SA) on multiple shoot induction and their impact on ethylene production using embryonal cotyledon cultures of Cucumis sativus L. were examined. The optimum concentration of $AgNO_3\;(40{\mu}M),\;CoCl_2\;(20{\mu}M)\;and\;SA\;(20{\mu}M)$, separately, induced maximum number of shoots on Murashige and Skoog's (MS) medium supplemented optimally with $4.44{\mu}M$ BA and $0.25{\mu}M$ NAA. Among the three ethylene inhibitors tested, $AgNO_3$ produced maximum number of shoots when compared to $CoCl_2$ and SA Ethylene production was monitored in all the treatments with $AgNO_3/CoCl_2/SA$ and it was observed that the treatment with $AgNO_3$ alone showed increase in ethylene production when compared to $CoCl_2$ and SA Even though ethylene concentration was the highest in $AgNO_3$ treated explants, maximum number of shoots was obtained.

• 한국수소및신에너지학회논문집
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• 제35권2호
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• pp.140-145
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• 2024

High temperature co-electrolysis of H₂O-CO₂ mixtures using solid oxide cells has attracted attention as promising CO₂ utilization technology for production of syngas (H₂/CO), feedstock for E-fuel synthesis. For direct supply to E-fuel production such as hydrocarbon and methanol, the outlet gas ratio (H₂/CO/CO₂) of co-electrolysis should be controlled. In this work, current voltage characteristic test and product gas analysis were carried out under various reaction conditions which could attain proper syngas ratio.

• Asian-Australasian Journal of Animal Sciences
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• 제23권6호
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• pp.700-707
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• 2010

Effects of protease-resistant antimicrobial substances (PRA) produced by Lactobacillus plantarum and Leuconostoc citreum on rumen methanogenesis were examined using the in vitro continuous methane quantification system. Four different strains of lactic acid bacteria, i) Lactococcus lactis ATCC19435 (Control, non-antibacterial substances), ii) Lactococcus lactis NCIMB702054 (Nisin-Z), iii) Lactobacillus plantarum TUA1490L (PRA-1), and iv) Leuconostoc citreum JCM9698 (PRA-2) were individually cultured in GYEKP medium. An 80 ml aliquot of each supernatant was inoculated into phosphate-buffered rumen fluid. PRA-1 remarkably decreased cumulative methane production, though propionate, butyrate and ammonia N decreased. For PRA-2, there were no effects on $CH_4$ and $CO_2$ production and fermentation characteristics in mixed rumen cultures. The results suggested that PRA-1 reduced the number of methanogens or inhibited utilization of hydrogen in rumen fermentation.

• 청정기술
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• 제28권1호
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• pp.9-17
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• 2022

전기화학적 이산화탄소 환원 기술은 전기에너지를 이용하여 대표적인 온실가스인 이산화탄소를 유용한 기초 화학제품으로 전환시킬 수 있는 유망한 기술 중 하나다. 특히, 다양한 후보 제품 중 일산화탄소는 높은 Faraday 효율과 우수한 경제성을 나타내기 때문에 학계와 산업계의 많은 관심을 받고 있다. 과거 여러 연구진이 본 기술의 온실가스 저감 잠재량을 정량적으로 분석했으나, 분석 과정에서 도입된 과정과 사용된 인벤토리 데이터의 일관성 및 투명성에 문제가 제기된다. 본 연구에서는 전기화학적 이산화탄소 환원을 통한 일산화탄소 생산 공정의 온실가스 저감 잠재량 분석을 위한 전과정평가를 수행했다. 세 종류의 시스템 경계를 정의 후 각각의 지구온난화지수를 화석연료 기반 일산화탄소 생산 공정과 비교했다. 분석 결과, 전기화학적 일산화탄소 생산 기술을 도입하여 온실가스를 저감하기 위해서는 전해조 구동에 필요한 전기에너지의 배출계수가 현재 국내 발전부문의 배출계수보다 충분히 낮아야 한다는 점을 확인했다. 또한, 신뢰성 있는 온실가스 저감 잠재량 분석을 위해서는 기존의 화석연료 기반 일산화탄소 생산 공정의 인벤토리 정보를 투명하게 공개하는 것이 중요함을 밝혔다.