• Journal of Microbiology and Biotechnology
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• 제23권11호
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• pp.1598-1609
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• 2013

Organochlorine pesticide residues continue to remain as a major environmental threat worldwide. Lindane is an organochlorine pesticide widely used as an acaricide in medicine and agriculture. In the present study, a new lindane-degrading yeast strain, Pseudozyma VITJzN01, was identified as a copious producer of glycolipid biosurfactant. The glycolipid structure and type were elucidated by FTIR, NMR spectroscopy, and GC-MS analysis. The surface activity and stability of the glycolipid was analyzed. The glycolipids, characterized as mannosylerythritol lipids (MELs), exhibited excellent surface active properties and the surface tension of water was reduced to 29 mN/m. The glycolipid was stable over a wide range of pH, temperature, and salinity, showing a very low CMC of 25 mg/l. Bio-microemulsion of olive oil-in-water (O/W) was prepared using the purified biosurfactant without addition of any synthetic cosurfactants, for lindane solubilization and enhanced degradation assay in liquid and soil slurry. The O/W bio-microemulsions enhanced the solubility of lindane up to 40-folds. Degradation of lindane (700 mg/l) by VITJzN01 in liquid medium amended with bio-microemulsions was found to be enhanced by 36% in 2 days, compared with degradation in 12 days in the absence of bio-microemulsions. Lindane-spiked soil slurry incubated with bio-microemulsions also showed 20-40% enhanced degradation compared with the treatment with glycolipids or yeast alone. This is the first report on lindane degradation by Pseudozyma sp., and application of bio-microemulsions for enhanced lindane degradation. MEL-stabilized bio-microemulsions can serve as a potential tool for enhanced remediation of diverse lindane-contaminated environments.

• 한국재료학회지
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• 제20권7호
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• pp.379-384
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• 2010

The usual ceramic process of mixing and milling in state of oxides $ZrO_2$ and $CeO_2$ was adopted in this study in a wet process to manufacture Ce-TZP. $CeO_2$-$ZrO_2$ ceramics containing 8~20 mol% $CeO_2$ were made by heat treatment at $1250\sim1500^{\circ}C$ for 5hr. The maximum dispersion point of every slurry manufactured with a mixture of $ZrO_2$ and $CeO_2$ was neat at pH10. A stable slurry with average particle size of 90 nm can be manufactured when it is dispersed with the use of ammonia water and polycarboxylic acid ammonium. The sintered Ce-TZP ceramics manufactured with the addition of $CeO_2$ in a concentration of less than 10 mol% progressed to the fracture of the specimen due to the existence of a monoclinic phase of more than 30% at room temperature. More than 99% of the tetragonal phase was created for the sintered body with the addition of $CeO_2$ beyond 18 mol%, but the degradation of the mechanical properties on the entire specimen was brought about due to the $CeO_2$ existing in a percentage above 3%. Consequently, the optimal Ce-TZP level combined in the oxide state was identified to be 16 mol% of $CeO_2$ contents.

• 한국주조공학회지
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• 제28권6호
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• pp.256-260
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• 2008

The Hybrid-Lower Arm, which has been developed for reducing cost and weight, was produced by three kinds of casting methods such as the high-pressure diecasting(HPDC), the squeeze casting(SC), and the H-NCM rheocasting process. The important factors for development of the Hybrid-Lower Arm are the integral feeding in Al casting for heat treatment and the high joinning ratio between the steel part and the Al part. In this study, effects of these casting processes on the quality of Hybrid-Lower Arm were investigated. Compared with HPDC and squeeze casting, the rheocasitng process using the H-NCM slurry had some advantages in joinning different materials of Al and steel pipe without deforming the steel pipe. X-ray analysis also showed the poreless microstructure in semisolid Hybrid-Lower Arm. In the torsion stress test, semisolid Hybrid-Lower Arm was satisfied with the requirements of automobile standard.

• 한국건축시공학회지
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• 제14권5호
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• pp.389-396
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• 2014

숏크리트의 필수 구성요소 중 하나인 급결제는 높은 pH환경에서 거동하는 경우가 많고 이를 억제하기 위해 개발된 시멘트 광물계 분말형 급결제 또한 작업시 다량의 분진 발생으로 인하여, 여러 환경적 문제를 일으키고 있다. 본 연구에서는 이러한 문제점을 해결하기 위하여 슬러리형의 급결제를 도입하고, 기본적인 물성 파악을 위해 숏크리트 배합에 혼화재로서 자주 활용되는 슬래그의 혼입에 따른 숏크리트 재료의 응결 및 경화특성, 강도 특성 및 염화물 이온 침투 저항성을 평가하였다. 슬래그의 혼입에 따른 응결 경화의 촉진 및 1일 압축강도의 발현은 $C_{12}A_7$과 황산칼슘의 수화반응에서 생성된 에트링가이트상의 양과 관련이 있는 것으로 보이며, 3일 강도 이후의 물성은 일반적인 규산3칼슘의 수화반응과 관련이 있는 것으로 나타났다. 염화물 이온침투 저항성의 경우, 슬래그의 혼입량이 증가하면 훨씬 개선되는 것으로 나타나, 향후 이러한 배합에 대한 내염해성의 정밀한 평가가 필요한 것으로 나타났다.

• 아시안잔디학회지
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• 제26권1호
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• pp.44-53
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• 2012

친환경적인 코스관리를 위해 가축분뇨액비를 활용하는 것은 매우 효과적인 방법이지만 시비 후 토양 및 주변수계에 미치는 영향에 대한 조사는 미흡하다. 가축분뇨액비(SCB)와 화학비료(CF)를 살포한 후 토양과 수질을 주기적으로 모니터링하여 골프코스의 환경에 미치는 영향을 평가하였다. SCB 액비의 시비는 화학비료 시비 때보다 골프코스의 토양오염은 나타나지 않았고, 유기물함량, 양이온치환용량 및 치환성 칼슘이 감소하였다(P<0.01). 주변 연못물의 모니터링에서 수질의 오염은 나타나지 않았으며, SCB가 시비된 주변연못의 pH와 질소함량이 감소하였다(P<0.01). 토양과 수질의 특성 조사에서 SCB의 시비는 토양 중 유기물과 양이온치환용량을 감소시키고, 수질의 SAR를 증가시킨다(P<0.01). SCB와 CF의 질소시비는 토양의 질소함량 변화와 상관성이 높으나(P<0.01), 수질에 미치는 영향은 적었다. 이러한 결과를 종합할 때, 골프코스에서 SCB의 시비는 토양과 수질의 오염은 나타나지 않으며, 토양의 유기물과 연못물의 pH가 감소되어 토양의 대취량과 연못물의 조류의 감소효과가 기대되었다.

• 자원리싸이클링
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• 제15권3호
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• pp.20-29
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• 2006

본 연구는 인산부생석고를 결정성장시켜 고순도의 결정질 이수석고를 제조하여 다용도의 석고를 얻고자 하였다. $99^{\circ}C$의 수중에서 약 2시간 동안에 이수석고는 $\alpha$형의 반수석고로 탈수가 완료되었다. 수중탈수된 반수석고를 매정제 $Na_2SO_4$를 10wt%, 슬러리 농도는 20%, pH가 $5{\sim}6$, 결정성장온도 $65^{\circ}C$의 조건에서 4시간 동안 결정성장 시키면 장경이 $200{\mu}m$정도인 결정을 얻을 수 있었다. 결정성장이 끝난 슬러리를 325#로 습식사분하여 사상산물로 고순도 결정성장 석고를 얻었으며, 이 때 석고의 회수율은 약 93.9%, 순도는 99% 정도 였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제12권6호
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• pp.70-77
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• 2007

토양에 존재하는 다핵방향족탄화수소(Polycyclic Aromatic Hydrocarbons, PAHs)의 처리를 위하여 자연계로부터 분리된 균주는 Pseudomonas sp.로 동정되었으며, 이 균주를 KM1으로 명명하였다. 균주의 최적 성장조건은 회분식 배양에서 $35^{\circ}C$, pH 7로 나타났다. 분리균주 Pseudomonas sp. KM1에 의한 7-PAHs(naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, fluoranthene and pyrene)의 분해실험결과 배양 1일 만에 fluoranthene을 제외한 naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene and pyrene 이 분해됨을 확인할 수 있었다. 그리고 토양유무에 따른 PAHs 분해실험 결과, 흡착분배계수와 유기물함량(%)이 큰 신동방이 경방이나 봉동보다 분리균주에 의한 생분해율(%)이 낮았다. 토양에 오염된 유기화합물의 분배특성과 토양 내 유기물함량(%)이 오염된 토양의 생물학적 처리효과에 영향을 미치는 중요한 인자인 것으로 나타났다.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2000년도 추계 기술심포지움 논문집
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• pp.89-92
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• 2000

테입 캐스터를 이용하여 바인더/가소제, 글말함량 비율이 다른 LTCC 테입을 제작한 후 특성평가를 하고자 하였다. 슬러리 조성은 서로 다른 바인더/가소제 그리고 분말함량에 따라 각각 4개 조성으로 구성하였다. 모든 슬러리에서 발포나 핀홀이 없는 미려한 표면을 갖는 테입을 얻을 수 있었다. 가장 우수한 기계적 특성 특성은 B/P=3.0, 분말함량 70vo1%인 두께 52 $\mu\textrm{m}$인 테입에서 인장강도 4.6MPa, 신을 29.5%의 특성을 얻을 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제24권11호
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• pp.1484-1489
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• 2014

A novel esterase gene, est01, was successfully unearthed from a biogas digester microbiota metagenomic library. The 1,194 bp est01 gene encodes a protein of 44,804 Da (designated Est01). The amino acid sequence of Est01 shows only moderate (33%) identity to a lipase/esterase. Phylogenetic analysis and biochemical characterization confirmed that Est01 is a new member of family VIII esterases. The purified Est01 from recombinant Escherichia coli BL21 (DE3) showed high hydrolytic activity against short-chain fatty acid esters, suggesting that it is a typical carboxylesterase rather than a lipase. Furthermore, the Est01 was even active at $10^{\circ}C$ (43% activity remained), with the optimal temperature at $20^{\circ}C$, and had a broad pH range from 5.0 to 10.0, with the optimal pH of 8.0. These properties suggest that Est01 is a cold-adaptive esterase and could have good potential for low-temperature hydrolysis application.

• Asian-Australasian Journal of Animal Sciences
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• 제25권5호
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• pp.690-700
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• 2012

The experiment was conducted by in vitro fermentation and bacterial community analysis to investigate the reduction of odorous compounds in response to the use of feed additives (FA) during carbohydrate overload in growing pigs. Soluble starch at 1% (control) and various FA at 0.1% Ginseng meal (FA1); Persimmon leaf (FA2); Gingko nut (FA3) and Oregano lippia (FA4) were added to fecal slurry and incubated anaerobically for 12 and 24 h. In vitro parameters and microbial diversity of the dominant bacteria following fermentation were analyzed using Denaturing Gradient Gel Electrophoresis (DGGE), band cloning and sequencing of the V3 region. Results showed that total gas production increased with the advancement of incubation (p<0.05). pH values of FAs and control groups were decreased except the FA4 group which increased somewhat from 12 to 24 h (p<0.05). Ammonia nitrogen ($NH_3$-N) and $H_2S$ gas concentrations were comparatively lower in both stages in FA4 treatment than in the other groups (p<0.05). Hence, $NH_3$-N concentrations in liquid phases were increased (p<0.05) from 12 to 24 h, but the trend was lowest in FA4 than in the other groups at both stages. The total VFA production was comparatively lower and butyrate levels were moderate in FA4 group than in the the other groups during both stages (p<0.05). Indirect odor-reducing compounds such as $NO_2$, $NO_3$ and $SO_4$ concentrations were higher in the FA4 and FA3 than in the other groups at 24 h (p<0.05). After fermentation, ten dominant bands appeared, six of which appeared in all samples and four in only the FA4 treated group. The total number of DGGE bands and diversity was higher in the FA4-group compared to other groups. Additionally, similarity indices were lowest (71%) in the FA4, which represented a different bacterial community compared with the other groups. These findings indicate that $NH_3$-N, $H_2S$ and VFA production was minimal, and pH was also better in the FA4 group than in the other groups. Furthermore, the conversion of odor-reducing indirect compounds or their intermediates was higher in the FA4 group in compared to the other groups. FA4 group generated less odorous products and more indirect products by in vitro fermentation at 24 h, and their microbial pattern appeared to differ from that of the other groups. These findings suggest that this particular FA could change the microbial population, which may have a beneficial effect on odor reduction. It is recommended that the oregano lippia may be supplied to growing pigs as FA along with excess carbohydrate sources to reduce the production of odorous compounds.