• Journal of Biosystems Engineering
• /
• 제33권4호
• /
• pp.248-252
• /
• 2008

An experiment was conducted in order to investigate gasification characteristics of rice husks in a fixed bed, which was a pre-step to design a continuous gasification system. Two air supply levels for gasification were chosen and their effects on the producer gas amount and producer gas composition were discussed. The main components of the producer gas were CO, $CO_2$, $O_2$, $H_2$ and THC (Total HydroCarbon). As airflow rate decreased, more producer gas was produced. The peak amount of CO, $H_2$ and THC were 28%, 7.5% and 0.68% in volume when constant airflow rate of $3.36\;m^3/s$ was used in the batch operation. About 4.5 kg of ash (9%) and condensed water including tars of 6 kg (11%) were produced from 50 kg rice husks in the gasification. Excluding the byproducts, all rice husks seemed to be transformed into producer gas. This gasification study was conducted prior to developing a continuous gasification system for biomass including agricultural byproducts.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
• /
• pp.324-327
• /
• 2008

Microwave remote sensing has great potential, especially in monsoon Asia, since optical observations are often hampered by cloudy conditions. The radar backscattering characteristics of rice crop were investigated with a ground-based automatic scatterometer system. The system was installed inside a shelter in an experimental paddy field at the National Institute of Agricultural Science and Technology (NIAST) before transplanting. The rice cultivar was a kind of Japonica type, called Chuchung. The scatterometer system consists of X-band antennas, HP8720D vector network analyzer, RF cables, and a personal computer that controls frequency, polarization and data storage. This system automatically measures fully-polarimatric backscattering coefficients of rice crop every 10 minutes, accompanied by a digital camera that takes pictures in a fixed position with the same interval. The backscattering coefficients were calculated by applying a radar equation. Plant variables, such as leaf area index (LAI), biomass, plant height and weather conditions were measured periodically throughout the rice growth season. We have performed polarimetric decomposition of paddy data such as single, double and volume scattering to extract the scattering information effectively. We investigated the relationships between backscattering coefficients and the plant variables.

• 환경위생공학
• /
• 제13권1호
• /
• pp.185-194
• /
• 1998

Laboratory-scale investigation into initial anaerobic biofilm development was carried out by circulating mixed liquor from a steady-state anaerobic reactor through silicone tubing and then rerurning the mixed liquor to the reactor. The wall of the silicone tubing was the surface upon which anaerobic biofilm accumulation or development was monitored. Methanogenic bacteria accumulation was monitored by F$_{420}$ fluorescence (picomoles F$_{420}$/cm$^{2}$) of the extracted biofilm material. Biofilm accumulation was measured by the increase in COD of the extracted material ($\mu $g COD/cm$^{2}$). Experiments were conducted for 25 days, and biofilm analyses were performed at 5 days intervals. The results indicated that the initial rates of methangen and anaerobic biofilm accumulation increased with increasing organic loading rate and higher initial rates were observed for 15 days than 15 day liquid HRT or SRT. When the initial rates were plotted against the corresponding mixed liquor volatile suspended solids the difference between the results at the two HRT's became much less significant. Thus, the concentration of mixed liquor volatile suspended solids was found to be a very important parameter affecting initial anaerobic biofilm development. The ratio of methanogens to anaerobic biofilm was also investigated. The results showed that the ratio remained constant through the 25 days of each experiment and for high organic loading rates. Based on the results of this research, a reduction, a reduction of start-up period of anaerobic fixed film reactors might be achieved by maintaining a high organic loading and a large concentration of anaerobic microorganisms in the mixed liquor during the start-up period.

• Journal of Microbiology and Biotechnology
• /
• 제17권2호
• /
• pp.373-377
• /
• 2007

No phosphatidylcholine (PC) was detected in the membrane of Rhodobacter sphaeroides pmtA mutant (PmtAl) lacking phosphatidylethanolamine (PE) N-methyltransferase, whereas PE in the mutant was increased up to the mole % comparable to the combined level of PE and PC of wild type. Neither the fatty acid composition nor the fluidity of membrane was altered by pmtA mutation. Consistently, aerobic and photoheterotrophic growth of PmtAl were not different from wild type. However, PmtAl showed an extended lag phase (15 h) after the growth transition from aerobic to photoheterotrophic conditions, indicating the PC requirement for the efficient formation of intracytoplasmic membrane (ICM). Interestingly, the B800-850 complex of PmtAl was decreased more than twofold in comparison with wild type, whereas the level of the B875 complex comprising the fixed photosynthetic unit was not changed. Since puc expression is not affected by pmtA mutation, PC appears to be required for the proper formation of the B800-850 complex in the ICM of R. sphaeroides.

• 농업과학연구
• /
• 제49권3호
• /
• pp.463-481
• /
• 2022

Phosphorous (P) is considered to be one of the key essential elements demanded by crop plants. Approximately 70 - 90% of phosphatic fertilizers applied to crops are fixed in soil as Ca, Fe, and Al metal cations, which are insoluble and thus not readily available for plant uptake. Therefore, most soils are deficient in plant available P. This is usually rectified by applying phosphate fertilizers continuously, although this is not economically viable or environmentally acceptable. The present paper reviews the mechanisms involved with phosphate solubilization and mineralization by phosphate solubilizing microorganisms (PSMs) with the associated factors that determine the success. PSMs are effectively involved in mediating the bioavailability of soil P. Their contribution includes mineralization of organic P solubilization of inorganic P minerals, and storing sizable amounts of P in biomass through different mechanisms such as the production of organic and inorganic acids, H₂S, siderophores, exopolysaccharides, and production of enzymes such as phosphatases, phytase, and phosphonatases/C-P lyases, which are capable of chelating the metal ions, forming complexes, and making plant available P. PSMs manifest a wide range of metabolic functions in different environments, resulting in significantly higher plant growth, enhanced soil properties, and increased biological activities. Therefore, development of bio-inoculants with efficient novel PSM strains and further investigations on exploring such strains from diverse ecological niches with multifunctional plant-growth-promoting traits are needed.

• 대한환경공학회지
• /
• 제28권6호
• /
• pp.687-692
• /
• 2006

실험은 C/N 비가 낮은 실제하수 유입시 적용한 유동여재 $A_2O$시스템의 생물학적 탈질특성을 파악하고 외부 탄소원(메탄올) 주입량(C/N비) 변화에 따른 오염물질 제거특성, 각 반응조의 유기물, 질소 거동 특성을 검토하였다. 실험장치는 실험실 규모로 호기조에 유동여재를 투입하여 부유와 부착 미생물이 공존하는 혼합형 형태이다. 유동여재는 $10{\sim}20mm$정도의 육면체로 된 스폰지 형태의 폴리우레탄 재질이다. 실험에서 얻어진 결과는 다음과 같다. 외부탄소원을 주입하지 않는 하수처리의 경우, 부유성 미생물양이 부착성 미생물양 보다 약 3배 가량 많았다(총 미생물량 80 g). 무산소조에 주입되는 외부탄소원에 의해 성장되는 미생물은 우선적으로 호기조 접촉여재에 일정량 부착된 후에 부유성 상태 미생물로 유지되었다. 유출수 $COD_{Cr}$ 농도는 외부탄소원 주입여부에 관계없이 $13{\sim}29mg/L$으로 안정하게 유지되었다. 유출수의 총무기성 질소(TIN)농도의 경우, 미주입시에는 $20.0{\sim}35.9mg/L$(제거효율 18%)이었으나 주입시에는 $2.5{\sim}9.0mg/L$(제거효율 $71{\sim}83%$)로 염분의 영향은 없었다. 각 반응조의 유기물($COD_{Cr}$) 제거특성은 외부탄소원 미주입시에는 대부분이 혐기조에서 제거되었으며, 외부탄소원 주입시에 대부분이 무산소조에서 제거되었다. 과잉주입의 경우 대부분이 호기조에서 제거되었다. 총 무기성 질소(TIN)의 경우, 외부탄소원 미주입시 대부분이 혐기조에서 제거되었으며, 외부탄소원 주입시 불안정한 상태에서는 혐기조에서, 안정한 상태에서는 무산소조에서 대부분 제거되었다.

• Journal of Ecology and Environment
• /
• 제42권2호
• /
• pp.60-69
• /
• 2018

Background: This study was conducted from March 2011 to February 2013 in order to evaluate the ecosystem value by examining the organic carbon distribution and cycling in the Quercus glauca forest, evergreen oak community at Seonheul-Gotjawal, Jeju Island. Results: The amount of organic carbon distribution was $124.5ton\;C\;ha^{-1}$ in 2011 and $132.63ton\;C\;ha^{-1}$ in 2012 for aboveground biomass. And it was $31.13ton\;C\;ha^{-1}$ in 2011 and $33.16ton\;C\;ha^{-1}$ in 2012 for belowground biomass. In total, the amount of organic carbon distribution in plants was 155.63 and $165.79ton\;C\;ha^{-1}$ in 2011 and 2012, respectively. In 2011 and 2012 respectively, the amount of organic carbon distribution was 3.61 and $6.39ton\;C\;ha^{-1}$ in the forest floor and it was 78.89 and $100.71ton\;C\;ha^{-1}$ in the soil. As shown, most carbon was distributed in plants. Overall, the amount of organic carbon distribution of the Q. glauca forest was $238.13ton\;C\;ha^{-1}$ in 2011 and $272.89ton\;C\;ha^{-1}$ in 2012. In 2011, the amount of organic carbon fixed in plants through photosynthesis (NPP) was $14.22ton\;C\;ha^{-1}\;year^{-1}$ and the amount of carbon emission of soil respiration was $16.77ton\;C\;ha^{-1}\;year^{-1}$. The net ecosystem production (NEP) absorbed by the Q. glauca forest from the atmosphere was $5ton\;C\;ha^{-1}\;year^{-1}$. Conclusions: The carbon storage value based on such organic carbon distribution was estimated about $23.81mil\;won\;ha^{-1}$ in 2011 and $27.29mil\;won\;ha^{-1}$ in 2012, showing an annual increment of carbon storage value by $3.48mil\;won\;ha^{-1}$. The carbon absorption value based on such NEP was estimated about $500,000won\;ha^{-1}\;year^{-1}$.

• 공업화학
• /
• 제29권3호
• /
• pp.350-355
• /
• 2018

본 연구에서는 굴참나무의 열분해 및 촉매 열분해에 바이오매스 반탄화가 미치는 영향에 대한 연구를 수행하였다. 굴참나무와 반탄화된 굴참나무의 열분해 및 촉매 열분해 거동은 열중량분석 결과와 회분식반응기를 이용한 급속열분해 반응에서 얻어진 바이오오일의 생성물분포를 비교하여 평가하였다. 굴참나무와 반탄화된 굴참나무의 열중량 곡선 및 미중열중량곡선은 굴참나무 내 헤미셀룰로오스의 제거량은 반탄화 온도 및 시간을 증가시킴에 따라 증가됨을 나타내었다. 굴참나무의 반탄화과정에서 헤미셀룰로오스의 제거로 굴참나무 내 셀룰로오스와 리그닌의 함량이 증가되기 때문에 열분해 과정에서 오일의 수율은 감소하고 고형 촤 수율은 증가하였다. 반탄화 굴참나무의 열분해 오일 중 레보글루코산과 페놀류의 선택도는 굴참나무 열분해 오일에 비해 높았다. 바이오오일 중 방향족 화합물의 함량은 HZSM-5 ($SiO_2/Al_2O_3=30$) 상에서 굴참나무 및 반탄화된 굴참나무의 촉매열분해를 적용함으로써 증가되었다. 굴참나무에 비해, 반탄화 굴참나무는 HZSM-5를 이용한 촉매 열분해를 통한 방향족화합물 형성에 더 높은 효율을 보였고 더 높은 반탄화 온도($280^{\circ}C$) 및 반응온도($600^{\circ}C$)를 적용함으로써 극대화되었다.

• KSBB Journal
• /
• 제20권1호
• /
• pp.26-33
• /
• 2005

유기성 폐기물의 composting에 사용된 토양유래의 복합 발효 미생물 제제로부터 분리, 동정된 다당 생성 균주인 Enterobacter sp.를 이용하여 서로 다른 기질 및 이의 농도에 따른 발효 특성을 조사하였다. 본 균주는 단당 및 단당의 혼합 탄소원인 경우보다는 lactose에서의 균체 생육 및 다당 생산량이 매우 높아 lactose를 효율적으로 이용하는 특징을 보였다. 공급된 lactose는 $20\%$ 정도가 galactose로 발효액에 축적되어 서서히 감소하였고, glucose는 소량이 존재하였으나, 곧 고갈되었다. 한편, lactose 농도를 증가시킨 결과, 효소 활성도의 증가폭은 약 $350\~450$ unit를 나타내었다. 즉, lactose의 분해 효소 활성도는 다당 생성 경향과 잘 일치하여 $\beta-galactosidase$에 의해 lactose가 구성당인 glucose와 galactose로 분해되는 과정에서 다당이 생성되는 것으로 추론되었다. 또 lactose 배지에 첨가한 glucose와 galactose는 각각 효소 생성의 repressor와 inducer로써 작용하는 것으로 판단하였다. 한편, 탄소원 농도를 증가한 결과, 비증식속도 $(0.133\~0.151hr^{-1})$에는 거의 영향을 미치지 않았고, 균체량의 차이를 나타내었으며, 고농도의 탄소원을 사용할 경우는 배지내의 잔존 당량이 높아져 수율이 감소하였으므로, 다당 생산의 최적 lactose 농도는 $30\~70g/L$인 것으로 판단하였다. 반면, 탄소원의 농도를 각각 30 및 70 g/L로 고정시킨 후, 질소원의 농도를 달리하였을 때는 질소원 농도의 증가로 균체량보다는 비증식속도가 $0.059\~0.225 hr^{-1}$ 및 $0.141\~0.237 hr^{-1}$로 크게 증가하므로 질소원이 증식 속도의 제한 기질로 작용하는 것으로 판단하였다.

• 접착 및 계면
• /
• 제24권1호
• /
• pp.26-35
• /
• 2023

일반적으로 유기 용매를 이용한 코팅제는 제조 과정에서 발암성 물질인 휘발성 유기화합물 (Volatile Organic Compounds, VOC)을 배출하게 되어 환경적인 문제로 사용이 규제되고 있다. 게다가 기존의 화석 연료 자원이 한정적이라 에너지 자원 고갈을 야기시킨다는 문제가 있다. 따라서 본 연구에서는 바이오매스 물질인 isosorbide의 함량을 달리하여 광경화형 바이오매스계 우레탄 아크릴레이트 올리고머를 합성하여 코팅제의 물성 평가를 진행하였다. Isosorbide 함량이 증가할수록 점도, 유리전이온도, 인장강도, 내오염성, 연필경도 등이 증가하였고 신율 및 굴곡성은 낮게 측정되었으며, 부착력은 BOI-3가 가장 좋은 결과를 나타내었다. 올리고머의 isosorbide 함량을 20% 로 고정하고 polycaprolactone diol(PCL)과 Ecoprol H1000(Ecoprol)의 함량비에 따라 광경화형 바이오매스계 우레탄 아크릴레이트 올리고머를 합성하여 코팅제의 물성 평가를 진행하였다. PCL/Ecoprol의 함량비가 증가할수록 유리전이온도, 신율 및 굴곡성은 증가하였지만 인장강도와 연필경도는 감소하였으며, PCL 첨가로 인한 표면 결합력 향상으로 부착력과 내오염성이 크게 증진한 것을 확인할 수 있었다. 합성된 올리고머의 필름은 모두 변색 없이 투명한 결과를 나타내었다.