• KSBB Journal
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• v.18 no.6
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• pp.473-478
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• 2003

The purpose of this study is to look for the optimal conditions of methane production. The conditions tested for methane production enhancement were temperature, pH, carbon source, nitrogen source, and inhibitor which can affects methane production. As a result, optimal conditions for methane production were 30$^{\circ}C$, neutral pH, methanol as a carbon source, NH$_4$Cl as a nitrogen source. 2-Bromoethanesulfonic acid was used as an inhibitor which can affects methane production. Existence in broth less than 10mM, inhibited methane production. Organic acid measurements revealed that formic acid exists in broth as majority.

• Journal of the Korean Applied Science and Technology
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• v.22 no.3
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• pp.250-256
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• 2005

This study was aimed to investigate treatment feasibility of leachate from D landfill that is located in gyr대ungbuk. From the analytical results of leachate, organic and nonbiodegradable matters were contained in high concentration. Thus chemical treatment was introduced to degrade nonbiodegradable matters in pre or post biological process. Two types of Fenton oxidation were adapted in this study. The first one is pre treatment process before biological treatment. The second one is post treatment process after biological treatment. The optimal conditions of both treatment methods were investigated as follows. In case of pre treatment process, the optimal conditions appeared in $Fe^{+2}/H_2O_2$(mmol/mmol): 0.1, $H_2O_2/CODcr$(mg/mg): 27.0, pH: 3 and reaction time: 2hrs. On the other hand, in case of post treatment process, the optimal conditions appeared in $Fe^{2+}$(mmol/mmol): 0.14, $H_2O_2/COD_{cr}$(mg/mg): 57.4, pH: 3 and reaction time: 1.25hrs. In the above optimal conditions, high COD removal was obtained in pre and post treatment process. Also it can expect that Fenton oxidation converted nonbiodegradable matters into biodegradable matters.

• Food Science and Preservation
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• v.10 no.4
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• pp.554-559
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• 2003

The optimal culture conditions on bacteriocin producing of Lactobacillus sp. FF-3 isolated from Korean Dongchimi, were studied for enhancing its production with regard to environmental and nutritional factors. The optimal cultivation time, initial pH and temperature were 21 hours, pH 7.0 and 30∼37$^{\circ}C$ respectively. Optimal compositions of culture medium for bacteriocin production were glucose 3% as carbon source, tryptone 4% as nitrogen source, and manganese sulfate 0.005% as inorganic salt with other basal components. The maximum antimicrobial activity was 484 BU/mL under the optimal culture condition.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.298-300
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• 2002

The design of a measurement system to perform Harmonic State Estimation (HSE) is a very complex problem. In particular, the number of available harmonic instruments(Continuous Harmonic Analysis in Real Time : CHART) is always limited. Therefore, a systematic procedure is needed to design the optimal placement of measurement points. This paper presents a new HSE algorithm which is based on an optimal placement of measurement points using Genetic Algorithms (GAs). This HSE has been applied to the New Zealand AC Power System for the validation of the new HSE algorithm. The study results have indicated an economical and effective method for optimal placement of measurement points using GAs in the HSE.

• Korean Journal of Food Science and Technology
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• v.50 no.2
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• pp.203-208
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• 2018

In this study, the hydrolysis conditions for the production of anti-inflammatory peptides from meat and roe hydrolysates of sandfish (Arctoscopus japonicus) were determined by measuring the nitric oxide (NO) scavenging enzymatic activity, experimental pH, temperature, enzyme concentration, and hydrolysis time. The optimal conditions determined when using meat hydrolysate were a pH value of 5.0, at a temperature of $30^{\circ}C$, 1% enzyme concentration, and 4 h hydrolysis time. The optimal conditions when using roe hydrolysate were a pH of 5.0, a temperature of $70^{\circ}C$, enzyme concentration of 3%, and hydrolysis time of 3 h. The NO scavenging activities of meat and roe hydrolysate were determined to be 18.94 and 19.81%, respectively. In summary, this study determined the optimum enzymatic hydrolysis conditions for the production of anti-inflammatory peptides from sandfish.

• Journal of Environmental Health Sciences
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• v.23 no.3
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• pp.109-120
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• 1997

The purpose of this study is to evaluate the effectiveness of wastewater treatment containing surfactant. For that, comparative analysis of effectiveness of Featon Oxidation, Aluminum Sulfate, PAC (Poly Aluminum Chloride) on the treatment of the synthetic wastewater containing LAS (Linear Alkyl Sulfate), a main component of the commercial detergent was carried. Then, the optimum pH, the dosage of reagents, and the concentration of the LAS in each treatment were determined. The results of the study were summarized as following. 1. In Fenton Oxidation, optimal pH was 3 and 97.92% removal of LAS was achieved. However, the increase of the pH reduced the efficiency of LAS removal. The proper chemical dosages of FeSO$_4$ and $H_2O_2$ were 300 mg/l and the increase of dosages didn't affected the removal efficiency. Therefore, it was concluded that the economic chemical dosage was 300 mg/l of FeSO$_4$ and $H_2O_2$. 2. In case of Alum treatment, optimal pH was 11 with 61.13% removal efficiency. At other pH range, the removal efficiency was very low indicating that removal efficiency is greatly influenced by pH. The proper chemical dosage was 200 mg/l with the removal efficiency of 77.65%. The increase of chemical dosage, however, reduced the removal efficiency. 3. In case of using PAC, optimal pH was 6 with 97.99% removal efficiency. The result showed that wastewaters containing surfactant were almost completely removed at pH 6 by PAC. Removal efficiency was decreased by increasing PAC dosage higher than 400 mg/l and dosage over 700 mg/l of PAC abolished the treatment. 4. The comparative analysis of three methods revealed that the effective pH ranges were at pH 2-5 with Fenton oxidation, at pH 6-11 with PAC, and pH 11 with Alum. The removal efficiencies at these pH were 83.95-97.92%, 75.98-97.99% and 61.13%, respectively. 5. Increase in LAS concentration reduced the removal efficiencies of all three methods. In the case of PAC or Alum treatment, treatment abolished at LAS concentration higher than 700 mg/l.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.571-574
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• 2000

Hydrolase is a group of the most widely used enzymes in industrial biological processes. Generally, their activities are easily changed with pH. With this characteristics, research for the optimal pH of hydrolases is required to obtain the optimization of process conditions. We selected xylanase, lysozyme, glucoamylase and barnase as model enzymes. To predict optimum pH of hydrolases, the calculation program based on Tanford-Kirkwood(TK) model was used. Results show that charge difference of catalytic residues is an important parameter deciding optimum pH and when charge difference of catalytic residues is maximum, optimum pH of the hydrolase establishes.

• Journal of Applied Biological Chemistry
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• v.54 no.3
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• pp.153-158
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• 2011

Optimal culture conditions were characterized for production of crude biosurfactant of Bacillus subtilis JK-1. During incubation of B. subtilis JK-1, the bacterial growth pattern, changes of the surface tension at variable temperatures, pH and NaCl concentrations in bacterial culture medium were studied. The strain was able to grow and produce biosurfactant at $15-45^{\circ}C$, in the pH range of 6-10, and at 0-10% (w/v) NaCl. In case, culture broth pH was gradually changed to neutral or weak alkaline. Optimal culture conditions for crude biosurfactant production were at $35^{\circ}C$ and pH 7.0 after 48 h incubation and the surface tension of biosurfactant was 24.0 mN/m. Besides, as the concentration of NaCl was increased from 0 to 10% (w/v), the growth was decreased, pH of the culture broth was converted from weak alkaline to acidic, and the surface tension rised.

• The Korean Journal of Food And Nutrition
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• v.8 no.3
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• pp.192-198
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• 1995

For the production of EMC, various professes and lipases were used to hydrolyse cheese sulk. The optimal conditions of various proteases were as follows, pronase-3$0^{\circ}C$, p14 7.0, pancreatln-4$0^{\circ}C$, pH 8.0, pacific protease-3$0^{\circ}C$, pH 7.0 and protease from Asp. sp. -5$0^{\circ}C$, pH 8.0. The optimal conditions of various lipases were as follows ; pancreatic lipase-5$0^{\circ}C$, pH 8.0, palatase ML-5$0^{\circ}C$, pH 7.0 and lipase form Candida -4$0^{\circ}C$, pH U.0. After hydrolysation under optimal conditions, the amounts of free amino acid and free fatty ac14 were increased with reaction time. Hydrolysates of pacific protease and pronase were showed high amount of free amino acid(0.67mg/ml and 0.74mg/ml). Especially EMC had high amount of glutamic acid and leucine. Lipase from Candida cylindracea produced high amount of free fatty acid (24.63 mg/ml) Butyric acrid, palmitic acid, stearic acid and oleic acid among free fatty acids were showed high amounts. Sensory evaluation of various MC were tasted nth 8 panelist. EMC produced with pancreatic lipase was most bitterness and EMC produced with palatase ML was best acceptable cheese flavor.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.1
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• pp.29-37
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• 2018

In this study, optimum extraction conditions for phosphorus recovery from sewage sludge ash(SSA) were investigated. For this purpose, an experiment was conducted to determine optimal recovery conditions for Ca-P type phosphorus by using calcium component in the recycled aggregate residue. The phosphorus content of sewage sludge ash was confirmed to be 5.0 %. When $H_2SO_4$ was used as an extract, concentration of 1 N $H_2SO_4$, L/S ratio of 10, and extraction time of 30 min were found to be the optimal extraction conditions. Phosphorus was extracted by using optimal extraction conditions, and then the heavy metals eluted with phosphorus were removed using 1~20 g of cation exchange resin. In 20 g of cation exchange resin, Fe 71.3%, Cu 82.4%, Zn 79.9%, and Cr 15% were removed. After that, the mixing ratio of the calcium extract obtained from the recycled aggregate residue (RAR) was changed to 1:1, 1:5, 1:10. The pH of the SSA to RAR mixture was adjusted to 2, 4, 8 and 12 by the addition of 5 N NaOH to the mixture of 1:5, and the phosphorus was recovered as Ca-P type precipitate. The optimum pH was 8. When recycled aggregate residues were used, the weight of calcium phosphate increased, but the amount of wastewater generated also increased. Therefore, it was concluded that the use of recycled aggregate residue was not economically feasible.