• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.627-631
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• 2007

The factors affecting on sludge sedimentation are reported as F/M ratio, ingredient, composition of influent substrate, dissolved oxygen concentration, temperature, pH, filamentous bacteria and SRT. Aeration tank applying Bacillus sp. has an important role for maintaining the dominant microorganism species to make steady progress for spore growth affecting sedimentation. This research aims to investigate the affecting factor for the sedimentation in B3 system and RABC system with aeration tank applying tapered aeration. Extracellular polymeric substances(EPS), protein and carbohydrate can be produced for the extreme condition, that is down to 0.2 mg/L of dissolved oxygen in the aeration tank. This research found out the relation between the sedimentation and the EPS production, especially the ratio of protein/carbohydrate. The spore of Bacillus sp. was formed at the low DO then microorganisms produced EPS. The results showed that the production of EPS was 109.95 mgEPS/gSS at 1.6 mg/L of DO, however it was 131.77 mgEPS/gSS at 0.5 mg/L of DO. The sedimentation was affected by protein content in EPS and the ratio of protein and carbohydrate. The settleability of sludge was not affected by the ratio of protein/carbohydrate in B3 process, meanwhile settleability was affected by the ratio of it in RABC process, respectively.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.140-143
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• 2005

This study was concerned with the optimization of liquid culture conditions for mycelial growth and polysaccharide production and its physicochemical properties in Cordyceps militaris. The one factor at a time method was adopted to investigate the effects of medium composition, environmental factors and C/N ratio. Among the these varialbles, glucose 80g/L, yeast extract 10g/L, $MgSO_4{\cdot}7H_{2}O\;0.5g/L$, $KH_{2}PO_4\;0.5g/L$ were proved to be the most suitable carbon, nitrogen, and mineral sources, respectively. The optimal temperature, initial pH, working volume were identified to be $24^{\circ}C$, 7.0 and 100ml, respectively. Under the optimal conditions, the strategies in shake flask culture and 5L jar fermentor led to mycelial growth of 29.43 g/L, 28.88g/L and polysaccharide production of 2.53g/L, 6.38 g/L, respectively. Among the phisicochemical properties, relative concentrations(w/v) of total sugar, uronic acid, protein and hexoseamine were identified to be 74.07%, 1.13%, 0.91%, and 0.46%, respectively. The fraction of neutral and acidic polysaccharide were identified to be 81.9% and 18.1%, respectively.

• Journal of Preventive Medicine and Public Health
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• v.27 no.4 s.48
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• pp.677-691
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• 1994

To evaluate the validity of serum pepsinogen levels as a screening tool for gastric cancer and adenoma, immunoradiometric assays of serum pepsinogen I level (PG I), II level (PG II) and esphagogastroduodenal endoscopies were done in 757 health examinees. Serum PG I level was higher in subjects with active duodenal ulcer (n=45, $75.2{\pm}34.3{\mu}g/l(mean{\pm}standard\;deviation)$, p<0.01) and gastroduodenal ulcers (n=8, $75.6{\pm}19.8{\mu}g/l$, p<0.05), and was lower in those with gastric adenoma(n=4, $37.7{\pm}37.2{\mu}g/l$, p<0.2) than those with normal, mild gastritis findings or ulcer scars (n=378, $56.6{\pm}24.9{\mu}g/l$. Serum PG II level was higher in subjects with active duodenal ulcer($17.2{\pm}13.8{\mu}g/l$, p<0.2), active gastro-duodenal ulcers ($18.3{\pm}7.4{\mu}g/l$, p<0.2) and gastric carcinoma (n=3, $23.8{\pm}10.9{\mu}g/l$, p<0.05) than those with normal, mild gastritis findings or ulcer scars $(14.5{\pm}7.9{\mu}g/l)$. Serum PG I/PG II ratio was higher in subjects with active duodenal ulcer($5.1{\pm}1.6$, p<0.05) and was lower in those with chronic gastritis(n=107, $4.1{\pm}1.7$, p<0.05), gastric polyp(n=19, $3.9{\pm}1.4$, p<0.2), gastric adenoma(n=4, $2.1{\pm}1.9$, p<0.01) and gastric carcinoma(n=3, $2.7{\pm}1.2$, p<0.1) than those with normal, mild gastritis findings or ulcer scars ($4.5{\pm}1.7$). Serum PG II level increased with age until 6th decade, whereas serum PG I/PG II ratio decreased with age in 378 subjects with normal, mild gastritis findings or ulcer scars. The screening criteria of serum PG I<$70{\mu}g/l$ and PG I/PG II ratio<3.0 for detecting gastric cancer and adenoma gave a positive rate of 15.7%, sensitivity of 57.1% and specificity of 84.7%.

• Journal of the Korean Wood Science and Technology
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• v.49 no.4
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• pp.287-298
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• 2021

Torch ginger (Etlingera elatior Jack) is a potential source of lignocellulose material for various derivative products. This study aims to determine the chemical components, ratio of syringyl to guaiacyl units (S/G) in lignin, and crystallinity of the biomass of torch ginger. The effects of soda pulping on the chemical characteristics of torch ginger pulp were also studied. Pulping of the chips was conducted with active alkali of 15%, 20%, and 25% and a Liquor-to-Wood (L/W) ratio of 4:1, 5:1, and 6:1. The impregnation and pulping times at maximum temperature (170℃) were 120 and 90 min, respectively. To assess the effect of treatments on the properties of pulping, a two-factorial experimental design was applied. Results showed that the content of α-cellulose and hemicellulose in the torch ginger was 48.48% and 31.50%, respectively, with an S/G ratio of 0.70 in lignin. Soda pulping changed the crystalline structure of the biomass from triclinic to monoclinic. Active alkali, L/W ratio, and interactions considerably influenced the observed responses. The degree of delignification increased with an increase in the loading of active alkali, which lead to a decrease in the kappa number of the pulp. An active alkali content of 25% and an L/W ratio of 6:1 resulted in the highest delignification selectivity with a kappa number of 2.78 and a yield of 24%. Given its cellulose content and ease of pulping, torch ginger can be a potential raw material for derivative products that require delignification as pretreatment. However, the increase in cellulose crystallinity should be considered when converting torch ginger to bioethanol.

• Food Science and Preservation
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• v.17 no.2
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• pp.281-289
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• 2010

We determined the optimum ethanolic conditions for extraction of $\gamma$-oryzanol and other functional components from rice bran, using response surface methodology (RSM). A central composite design was used to investigate the effects of the independent variables of solvent ratio ($X_1$), extraction temperature ($X_2$), and extraction time ($X_3$), on dependent variables including yield ($Y_1$), total phenolic content ($Y_2$), electron-donating activity ($Y_3$), ferulic acid level ($Y_4$), and $\gamma$-oryzanol concentration ($Y_5$). Solvent ratio and extraction temperature were the most important factors in extraction. The maximum yield was at 22.56 mL/g ($X_1$), 78.19C ($X_2$), and 522.15 min ($X_3$), at the saddle point. Total phenolic levels were little affected by solvent ratio or extraction temperature. The maximum concentration of extracted total phenolics was 90.78mg GAE/100 g at 21.26 mL/g, $94.65^{\circ}C$, and 567.97 min. A maximum electron-donating ability of 54.72% was obtained with the parameters 20.20 mL/g,$81.89^{\circ}C$, and 701.87 min, at the highest point. The maximum level of ferulic acid components was 210.47 mg/100g at 5.22 mL/g, $79.66^{\circ}C$, and 575.24 min. In addition, the maximum $\gamma$-oryzanol concentration was 660.39 mg/100g at 5.10 mL/g, $81.83^{\circ}C$, and 587.39 min. The optimum extraction conditions were a solvent ratio of 10.45 mL/g, $80^{\circ}C$ extraction temperature, and 535 min extraction time. Predicted extraction levels under optimized conditions were in line with experimental values.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.434-437
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• 2001

Shaking cultivation was carried out in 250 mL Erlenmeyel' flasks containing 60 mL of culture solution for 7 days. Artificial seawater was used as a basal culture medium. The cultivation was performed under the conditions that the temperature ranged from $4^{\circ}C$ to $32^{\circ}C$, the agitation speed 50 rpm to 200 rpm, and the sugar concentration 5 g/L to 35 g/L. The medium condition was cultured that sugar and nitrogen ratio 1.25 to 10. The biomass. the lipid content in biomass, and the DBA content of lipid were investigated according to the cultivation conditions. The lipid in biomass was distributed between 10 and 349'0, the DHA in lipid 34% to 43% of the lipid. and the biomass concentration 0.425 g/L to 4.50 g/L.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.238-238
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• 1996

각종 동물 및 인체 신장 유래 DHP-I에 의한 DA-1131, imipenem(IPM) 및 meropenem(MEPM)의 속도 상수를 측정한 결과, DA-1131은 동물종에 관계없이 가장 안정성이 큰 결과를 나타내었고, 인체 DHP-I에 대한 Vmax/Km 값이 IPM의 21.9%로 관찰되어 IPM보다 하위 기질인 것으로 확인되었다. DA-1131, IPM/CS 및 MEPM/CS의 20mg/kg투여 후의 혈중농도 반감기(T$_{1}$2/)는 각각 11.4분, 8.9분, 10.3분이었으며, 1$\mu\textrm{g}$/$m\ell$ 이상의 혈중농도룰 유지하는 시간은 66.6 분, 55.9 분, 63.1 분이었다. DA-1131, DA-l131/CS, IPM/CS, MEPM 및 MEPM/CS의 40 mg/kg 투여 후 24시간 동안의 뇨중 배설율은 57.9 %, 61.3%, 22.6 %, 11.3% 및 65.9%이었으며, 각 약물을 40 mg/kg 투여 15분 후 DA-ll3l의 폐중 농도는 11.2$\mu\textrm{g}$/g으로 DA-l131/CS, IPM/CS 및 MEPM/CS와 비슷한 결과를 나타내었으며 T/P ratio도 DA-1131, DA-l131/CS, IPM/CS 와 MEPM/CS 투여군에서 거의 동일한 것으로 확인되었다. 신장중 농도는 DA-1131 과 DA-l131/CS의 경우 29.l$\mu\textrm{g}$/g 및 34.2$\mu\textrm{g}$/g으로 큰 차이를 나타내지 않았으나, IPM/CS, MEPM 및 MEPM/CS 투여군에 비하여는 높은 결과로 나타났고 T/P ratio도 DA-1131과 DA-l131/CS 투여군이 IPM/CS, MEPM 및 MEPM/CS 투여군보다 놓은 것으로 확인되었다.

• Journal of Microbiology and Biotechnology
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• v.24 no.11
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• pp.1542-1550
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• 2014

Co-digesting molasses wastewater and sewage sludge was evaluated for hydrogen production by response surface methodology (RSM). Batch experiments in accordance with various dilution ratios (40- to 5-fold) and waste mixing composition ratios (100:0, 80:20, 60:40, 40:60, 20:80, and 0:100, on a volume basis) were conducted. Volatile solid (VS) concentration strongly affected the hydrogen production rate and yield compared with the waste mixing ratio. The specific hydrogen production rate was predicted to be optimal when the VS concentration ranged from 10 to 12 g/l at all the mixing ratios of molasses wastewater and sewage sludge. A hydrogen yield of over 50 ml $H_2/gVS_{removed}$ was obtained from mixed waste of 10% sewage sludge and 10 g/l VS (about 10-fold dilution ratio). The optimal chemical oxygen demand/total nitrogen ratio for co-digesting molasses wastewater and sewage sludge was between 250 and 300 with a hydrogen yield above 20 ml $H_2/gVS_{removed}$.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.499-506
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• 2005

This study was performed to investigate the effects of influent C/N ratio on the removal of organic and nitrogenous compounds by two nonwoven fabric filter bioreactors. The reactors were alternately aerated at an aeration/nonaeration period ratio of 60 min/60 min, and fed with wastewater only during nonaeration period. The influent C/N ratio (COD/TKN) was gradually reduced from 10 to 2. The influent was prepared by diluting the leachate from a foodwaste treatment facility in I city so that the COD concentration could be about 2,500 mg/L. The C/N ratio of the wastewater was adjusted by adding ammonium chloride. The results of the experiment showed that the COD and BOD concentration of the effluent was $40{\sim}54\;mg/L$ and $1{\sim}4\;mg/L$, respectively at the C/N ratios of $10{\sim}3$, and the effluent SS concentration was always below 2.0 mg/L. The T-N removal efficiencies were 96% or higher at C/N ratios of $10{\sim}5$, but decreased to 83% and 81%, respectively at the C/N ratios of 3 and 2.8. At the C/N ratios of 2.6 and 2, the effluent quality deteriorated due to ammonia toxicity. The fraction of nitrifying microorganism in the reactors increased from 10% to 20% as the C/N ratio decreased from 5 to 2.6. Alkalinity consumed were $3.12{\sim}3.49\;g$ alkalinity/g T-N removed at the C/N ratios of $10{\sim}5$, which are lower than the theoretical value of 3.57. However, the ratio increased to 4.63 and 4.87 g alkalinity/g T-N removed, respectively at the C/N ratios of 3 and 2.8.

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.36-46
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• 2004

We evaluated the effect of limiting nutrients and N/P ratio on the growth of phytoplankton in a small eutrophic reservoir from November 2002 to December 2003. Nutrient limitation was investigated seasonally using nutrient enrichment bioassay (NEB). DIN/DTP and TN/TP ratio (by weight) of the reservoir during the study period ranged 17${\sim}$187 and 13${\sim}$60, respectively. Most of nitrogen in the reservoir account for $NO_3$-N, but sharp increase of ammonia was evident during the spring season. Seasonal variation of dissolved inorganic phosphorus concentration was relatively small. DTP ranged 26.5${\sim}$10.1 ${\mu}g\;P\;L^{-1}$, and the highest and lowest concentration was observed in August and December, respectively. Chlorophyll a concentration ranged 28.8${\sim}$109.7 ${\mu}g\;L^{-1}$, and its temporal variation was similar to that of cell density of phytoplankton. Dominant phytoplankton species were Bacillariphyceae (Melosira varians) and Chlorophyceae (Dictyosphaerium puchellum) in Spring (March${\sim}$April). Cyanophyceae, such as Osillatoria spp., Microcystis spp., Aphanizomenon sp. dominated from May to the freezing time. TN/TP ratio ranged from 46 to 13 (Avg. 27${\pm}$6) from June to December when cyanobacteria (Microcystis spp.) dominated. p limitation for algal growth measured in all NEB experiments (17cases), while N limitation occurred in 8 out of 17 cases. The growth rates of phytoplankton slightly increased with decreasing of DIN/DTP ratio. Evident increase was observed in the N/P ratio of > 30, and it was sustained with DTP increase until 50 ${\mu}g\;P\;L^{-1}$. Under the same N/P mass ratio with the different N concentrations (0.07, 0.7and 3.5 mg N $L^{-1}$), Microcystis spp. showed the highest growth rate in the N/P ratio of< 1 with nitrogen concentration of 3.5 mg N $L^{-1}$). The responses of phytoplankton growth to phosphate addition were clearly greater with increase of N concentration. These results indicate that the higher nitrogen concentration in the water likely induce the stronger P-limitation on the phytoplankton growth, while nitrogen deficiency is not likely the case of nutrient limitation.