• 한국지하수토양환경학회지:지하수토양환경
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• 제17권6호
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• pp.52-58
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• 2012

Capillary fringe divides the groundwater and the vadose zone controlling the diffusive mass transfer of contaminants and gases. The thickness of capillary fringe is of great importance for the rate of contaminant mass transfer across the capillary fringe. Application of surface active chemicals including surfactants and alcohol-based products into the subsurface environment changes the surface tension of the aqueous phase, which in turn, affects the thickness of the capillary fringe. In this study, a bench-scale model was used to assess the quantitative relationship between the surface tension and the thickness of the capillary fringe. An anionic surfactant (Sodium dodecylbenzene sulfonate, SDBS) and an aqueous solution of ethanol were used to control the surface tension of the groundwater. It was found that the thickness of the capillary fringe is directly proportional to the surface tension. The air entry pressures measured by the Tempe Pressure Cell at different surface tensions using SDBS (200 mg/L) and ethanol (20%, v/v) solutions were in good agreement with the thicknesses of the capillary fringe measured by the model. A simple method to correct the conventional Brooks-Corey model for estimating the air entry pressure was also presented.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.105.1-105.1
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• 2010

바이오디젤 보급 활성화에 따른 식물성 원료유의 가격 상승 및 수급 불안정성 문제를 해결하고자 폐유지를 원료로 바이오디젤을 생산하고자 하는 시도가 이루어지고 있다. 폐유지의 사용은 폐자원 활용 측면에서 의미가 있으며 바이오디젤 생산 단가를 낮출 수 있다. 다양한 폐유지가 산업체로부터 배출되며 이 중에서 dark oil은 식용유 공장에서 식물성 원료유의 정제 과정에서 생기는 부산물로 바이오디젤로 전환 가능한 성분을 포함하고 있다. 본 연구에 사용된 dark oil은 54.9%의 유리지방산과 28.0%의 triglyceride, 4.4%의 diglyceride, 그리고 1% 이하의 monoglyceride를 함유하고 있다. Dark oil의 초기 산가는 109.8 mg KOH/g이었다. 본 연구에서는 dark oil의 유지 부분(triglyceride, diglyceride, monoglyceride)을 유리지방산으로 전환시켜 HAAO(high acid acid oil)을 생산한 후, 고체 산 촉매에 의한 에스테르화 반응을 통하여 바이오디젤을 생산하고자 하였다. 유지 부분의 유리지방산 전환 반응을 위하여 음이온성 계면활성제인 SDBS(sodium dodecyl benzene sulfonate)가 사용되었다. Dark oil:황산:물의 질량비가 10:2:10이고 SDBS가 오일 대비 3%인 조건에서 dark oil의 산가는 190.8 mg KOH/g까지 증가하였고, dark oil:황산:물의 질량비가 10:4:10이고 SDBS가 2%인 조건에서는 산가가 194.2 mg KOH/g까지 증가하였다. 생산된 HAAO을 이용하여 오일 대비 30%의 Amberlyst-15 촉매 하에서 HAAO:메탄올 몰비 1:9인 조건에서 에스테르화 반응을 수행하였을 경우 FAME(fatty acid methyl ester) 함량은 81.3%까지 증가하였다. 고체 산 촉매로써 Amberlyst-15와 가격 면에서 저렴한 PC101을 비교하였을 경우 FAME 함량은 각각 80.7%, 77.9%로 비슷한 효율을 나타내었다. 생산된 바이오디젤의 FAME 함량을 높이기 위해 증류 공정을 필요로 하였다.

• 대한기계학회논문집A
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• 제22권1호
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• pp.177-189
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• 1998

The contents of this paper include a non-destructive technique for evaluating the degradation of the boiler superheater tube in a fossil power plant through an electrochemical polarization test. Correlation between Ip of polarization parameter and SP-DBTT for the superheater tubes in long-term use was obtained. 1.0Cr-0.5Mo steel was degraded by softening, and the degree of degradation was dependent upon carbides with Cr and Mo elements. Since brittle fracture at low temperature and ductile fracture mode at high temperature were shown, similarity between standard Charpy and small punch tests could be found. In addition, SP-DBTT showing the degree of degradation was higher, as the time-in use of the materials got longer. Electrolyte including picric acid of 1.3 g in distilled water of 100ml at 25.deg. C temperature and sodium tridecylbenzene sulfonate with 1g could be applied to evaluate the degradation of 1.0Cr-0.5Mo steel by means of the electrochemical polarization test. Ip and Ipa values measured through the electrochemical test are the appropriate parameters for representing the degradation of the superheater tube(1.0Cr-0.5Mo steel) for the fossil power plant. It is poassible to evaluate the degradation of materials with different time histories electrochemically, by Ip value only, at field test.

• 한국환경성돌연변이발암원학회지
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• 제22권3호
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• pp.137-141
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• 2002

본 연구는 분열형 효모 Schizosaccharomyces pombe에서 여러 가지 DNA 절제회복 및 유전자 발현에 관여하는 SNF2/SW12유전자의 기능을 연구하기 위하여 이에 관련되는 유전자를 분리하고 그 특성을 연구하였다. SNF2 motif 의 conserved sequence를 primer로 하여 중합효소 연쇄반응(PCR) 방법으로 480 bp 크기의 DNA fragment를 분리하여, 이를 probe로 하여 효모에서 hrp2＋ 유전자를 분리하였다. 분리한 hrp2＋ 유전자의 sequence homology를 비교한 결과 3개의 SNF2 motif를 포함하고 있었다. hrp2＋유전자의 전사체 크기는 4.7 kb임을 Northern hybridization으로 확인하였다. hrp2＋유전자의 전사 개시 부위를 알기 위하여 primer extension분석을 한 결과, 첫 번째 ATG에서 약47 base pair 위쪽에 위치함을 확인하였다. 또한 특성 연구를 위하여 Northern hybridization으로 hrp2＋ 유전자의 UV와 MMS에 대한 유도성을 조사한 결과 자외선에 대해서만 유전자의 발현이 유도되었다. 이 결과 분리한 hrp2＋는 UV-inducible 유전자임을 확인하였다.

• Journal of Crop Science and Biotechnology
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• 제11권2호
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• pp.119-126
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• 2008

Since somatic embryogenesis combined with ethylmethane sulfonate(EMS) treatments is the most efficient technique for mutagenesis, the embryogenic capacity of four soybean cultivars was evaluated at different EMS concentrations, treatment times, and preculture durations. Two to 4 mm long immature cotyledons were placed in induction medium after EMS treatment, and the numbers of somatic embryos formed per explant were counted four weeks after culture initiation. We observed genotypic differences in the efficiency of somatic embryogenesis from immature embryos among four cultivars treated with different concentrations of EMS for six hours. Cultivars, Sinpaldalkong 2 and Jack, displayed highly efficient somatic embryogenesis regardless of EMS concentration, whereas very low efficiency or no survival was observed in Jinju 1 and Iksannamulkong cultivars. Preculture duration did not influence the efficiency of somatic embryogenesis. Because Sinpaldalkong 2 exhibited the best somatic embryogenesis, much higher concentrations of EMS were used to test somatic embryo formation under different periods of time in this cultivar. Three and six hour treatments with both 1 and 2 mM EMS yielded higher embryo formation than longer periods of time. Increasing the time with embryos in 2 mM EMS caused a reduction in somatic embryogenesis in Sinpaldalkong 2, but many chlorophyll-deficient soybean variants were identified in the $M_1R_0$ and $M_2R_1$ generations. In addition to Jack, Sinpaldalkong 2 is a good genotype for plant regeneration from EMS-treated immature embryo cultures.

• 한국작물학회지
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• 제59권2호
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• pp.128-133
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• 2014

Rapeseed (Brassica napus L.) oil with high oleic acid content is of great interest for both food and non-food uses. The 'Tamla' variety, characterized by oleic acid content of approximately 69%, was treated with 1% ethyl methane sulfonate (EMS) to induce mutations in the fatty acid biosynthesis pathway. $M_1$ plants were selfed and subsequent generations ($M_2$, $M_3$, and $M_4$ mutants) were analyzed to identify mutants having increased levels of oleic acid. $M_2$ mutants showed oleic acid content ranging from 13.5% to 76.9% with some mutants (TR-458 and TR-544) having up to 74.7% and 76.9% oleic acid, which was an increase of nearly 5% and 7%, respectively, compared to untreated cv 'Tamla'. We selected two $M_3$ mutants with >75% oleic acid content. One mutant (TR-458-2) had increased oleic acid (75.9%) and decreased linoleic acid (12.5%) and linolenic acid (4.4%) contents. The other (TR-544-1) showed increased oleic acid content (75.7%) and decreased linoleic acid (13.5%) and linolenic acid (3.3%) contents. The accumulation or reduction of oleic acid content in the selected $M_4$ mutants was also accompanied by a simultaneous decrease or increase in linoleic and linolenic acid contents. The high-oleic lines could be utilized further in breeding programs for improvement of rapeseed oil quality.

• 펄프종이기술
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• 제46권1호
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• pp.46-55
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• 2014

In this study, we modified the surface of nanofibrillated cellulose (NFC) through LbL (Layer-by-Layer) multilayering process with polyelectrolytes and investigated the effects of the NFC modification on the charge of NFC surface and the dewatering ability of NFC suspension. The multilayering process was done onto NFC fibers using polydiallyldimethylammonium chloride (PDADMAC) and poly-sodium 4-styrene sulfonate (PSS) under different dosage and washing conditions. When the washing was carried out in every adsorption stage, the modified NFC had strong cationic or anionic charge depending on the type of polyelectrolyte in the outermost layer and the dewatering ability was not affected. In the case of no washing treatment or washing in the final adsorption stage, however, the zeta potential of NFC was close to an isoelectric point so that the dewatering ability increased remarkably. Low addition level of polyelectrolytes also showed the similar results. The mixing of NFC suspensions with opposite charge resulted in higher network strength and improved dewatering ability due to the flocculation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.485-488
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• 2007

$SF_6$(sulfur hexafluoride)는 뛰어난 단열 및 아크방지능력(arc-extinguishingproperty)으로 인해, 전력용 변압기의 절연가스와 반도체${\cdot}$액정용 플라즈마 CVD로의 cleaning gas, 주물공장 covering gas 등으로 사용되고 있다. 하지만, $SF_6$의 지구온난화지수(global warming potential)는 $CO_2$대비 23,900배가 높아 기후변화에 미치는 영향이 $CO_2$보다 훨씬 크고, 대기 중 분해되지 않고 잔존하는 기간이 $CH_4$ 10년, $CO_2$ 및 CFCs는 100년으로 추정되는데 반해, $SF_6$는 3,200년으로 연간방출양이 작더라도 오랜 기간 누적되면 그 파장이 클 것으로 사료된다. 대부분의 가스 하이드레이트(고상결정상태)는 고압, 저온에서 형성가능 하지만, 불화가스에 대해서는 쉽게 결정화가 일어난다. $SF_6$는 3$^{\circ}C$, 2기압에서 고밀도 고상화가 되기 때문에 여러 기체와 흔합되어 있는 경우 $SF_6$만을 압축된 고상 결정상태를 형성, $SF_6$를 회수, 정제할 수 있으므로 불화가스 분리${\cdot}$회수에 기술적, 경제적 효과를 기대할 수 있다. 본 연구에서는 하이드레이트 촉진제로서 계면활성제(promoter) 첨가에 따른 $SF_6$ 하이드레이트 형성 및 해리과정 실험을 통해 효율적인 $SF_6$ 저감에 관한 적용기술을 연구해 보았다.

• 펄프종이기술
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• 제44권5호
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• pp.21-31
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• 2012

In this study, we modified the surface of ground calcium carbonate (GCC) with polyelectrolytes with different molecular weight using Layer-by-Layer (LbL) multilayering technique and investigated its effect on the paper properties. Polydiallydimethylammonium chloride (poly-DADMAC) and poly sodium 4-styrene sulfonate (PSS) which have different molecular weights were used for LbL multilayering. Zeta potential and particle size of the LbL modified GCC were measured. After preparation of handsheets, their structural and mechanical properties were evaluated. The zeta potential and average particle size of the modified GCC were affected by the molecular weight of anionic polyelectrolyte (PSS). The zeta potential was higher and the particle size was smaller when GCC was treated by PSS with high molecular weight compared to the case with low molecular weight of PSS. The tensile and internal bond strength of the handsheets was increased with an increase in the number of layers on GCC particles, but the molecular weight of polyelectrolyte did not significantly affect the paper strength.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1330-1336
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• 2005

Polyhydroxyalkanoic acid (PHA) inclusion bodies were analyzed in situ by $^{13}C$-nuclear magnetic resonance ($^{13}C$-NMR) spectroscopy. The PHA inclusion bodies studied were composed of poly(3-hydroxybutyrate) or poly(3hydroxybutyrate-co-4-hydroxybutyrate), which was accumulated in Hydrogenophaga pseudoflava, and medium-chain-length PHA (MCL-PHA), which was accumulated in Pseudomonas fluorescens BM07 from octanoic acid or 11-phenoxyundecanoic acid (11-POU). The quantification of the $^{13}C$-NMR signals was conducted against a standard compound, sodium 2,2-dimethyl-2-silapentane-5-sulfonate (DSS). The chemical shift values for the in vivo NMR spectral peaks agreed well with those for the corresponding purified PHA polymers. The intracellular degradation of the PHA inclusions by intracellular PHA depolymerase(s) was monitored by in vivo NMR spectroscopy and analyzed in terms of first-order reaction kinetics. The H. pseudoflava cells were washed for the degradation experiment, transferred to a degradation medium without a carbon source, but containing 1.0 g/l ammonium sulfate, and cultivated at $35^{\circ}C$ for 72 h. The in vivo NMR spectra were obtained at $70^{\circ}C$ for the short-chain-length PHA cells whereas the spectra for the aliphatic and aromatic MCL-PHA cells were obtained at $50^{\circ}C\;and\;80^{\circ}C$, respectively. For the H. pseudoflava cells, the in vivo NMR kinetics analysis of the PHA degradation resulted in a first-order degradation rate constant of 0.075/h ($r^{2}$=0.94) for the initial 24 h of degradation, which was close to the 0.050/h determined when using a gas chromatographic analysis of chloroform extracts of sulfuric acid/methanol reaction mixtures of dried whole cells. Accordingly, it is suggested that in vivo $^{13}C$-NMR spectroscopy is an important tool for studying intracellular PHA degradation in terms of kinetics.