• Journal of the Korea Institute of Building Construction
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• v.17 no.1
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• pp.1-8
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• 2017

Recently, because of the terrorisms or warfare, the damages of human life or facilities have been increased. Hence, the Korean government launched the research group for high performance fiber reinforced cementitious composite (HPFRCC) with increased demanding on protecting and anti-explosive structures. Therefore, in this research, to apply the HPFRCC on military facilities with optimum performance on workability and performance, the fundamental properties and reduction of autogenous shrinkage of HPFRCC with various combinations of steel and organic fiber and emulsified refined cooking oil (ERCO) were evaluated. As a result, based on the comprehensive analysis, for favorable workability, strength, and autogenous shrinkage, 1.5 % of combined fiber of short steel fiber and long organic fiber and 0.5 % of ERCO was suggested as an optimum conditions.

• KSBB Journal
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• v.19 no.4
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• pp.245-249
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• 2004

A combined method of autolysis and enzymatic hydrolysis of baker's yeast was developed for the production of yeast extract, which is widely used as a natural food ingredient. From statistical analysis, NaCl and ethanol addition were found to be significantly effective factors in autolysis of yeast. The optimum dosages of salt and ethanol were 3% and 1%, respectively. Heat treatment and the use of cell lytic enzyme were not significantly effecting on the autolysis. Yeast hydrolysate was prepared by autolysis, followed by enzymatic hydrolysis using proteases, nuclease and deaminase. Additionally, the hydrolysate was processed by downstream process including Maillard reaction and debittering. The total dry matter yield and total nitrogen yield for the process were 76% and 59%, respectively. Compared to a process using brewer's yeast, when baker's yeast was used as a raw material, a higher recovery yield was obtained.

• Journal of Korean Society of Water and Wastewater
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• v.8 no.1
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• pp.1-8
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• 1994

Laboratory experiments were conducted to investigate the effect of digestion temperature on the settleability and dewaterability of anaerobically digested sludge. The digesters were operated at a hydraulic retention time of 20 days with a loading rate of 0.63~0.66kg volatile solids per cubic meter per day at the temperature of $35^{\circ}C$ and $55^{\circ}C$. A mixed primary and secondary municipal sludge was used as a feed. The interface height of the sludge during settling test was recorded to identify settleability. As a measure of dewaterability of the sludge, specific resistance and capillary suction time were also measured with and without chemical conditioning. Higher digestion efficiency was obtained at $55^{\circ}C$ than $35^{\circ}C$. However, the settleability and dewaterability of the sludge at $35^{\circ}C$ were quite higher than those of the sludge digested at $55^{\circ}C$. The optimum dosages of ferric chloride for sludge conditioning were 0.4% and 0.6% at $35^{\circ}C$ and $55^{\circ}C$, respectively. The filtrate COD of the sludge digested at $55^{\circ}C$ was higher than at $35^{\circ}C$, which means that poor dewaterability of the sludge result in high filtrate COD.

• Advances in Traditional Medicine
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• v.7 no.4
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• pp.418-425
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• 2007

The study was to evaluate the antihyperglycemic activity of Biophytum sensitivum (L.) DC in different extracts. Albino Wistar rats with alloxan hydrate induced diabetes were divided into 7 groups of 6 each. Both aqueous and methanolic extract of Biophytum sensitivum were prepared and given individually at different doses to different batches of rats (both normal and diabetic rats) after an overnight fast. Methanolic extract at the dose of 200 mg/kg body weight showed maximum blood glucose lowering effect in diabetic rats. The same dosages did not produce any hypoglycemic activity in normal rats. The antihyperglycemic activity of Biophytum sensitivum was compared with a standard drug Glibenclamide, an oral hypoglycemic agent. The above results suggest that maximum hypoglycemic effect was found only with a dose of up to 200 mg/kg b.w. of methanolic extract which is therefore the optimum dose for hypoglycemia and was used in all the experiments of the present study.

• Geomechanics and Engineering
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• v.28 no.3
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• pp.239-253
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• 2022

Suitable techniques to stabilize organic soil and improve its engineering behaviour are in demand. Despite various alternatives, nano-additives proved to be an effective stabilizer owing to their strength enhancing properties. The study focuses on using nano-silica as a potential stabilizer to improve organic silt. Soil was treated with four dosages of nano-silica namely 0.2%, 0.4%, 0.6% and 0.8% of dry weight of the soil. Nano-silica treated soil showed a strength increase of nearly 25% at a dosage of 0.4% after curing for two hours. Strength of the treated soil improved with age. Strength improved by nearly 62.9% after 28 days of curing and 221.4% after 180 days of curing due to formation of Calcium - Silicate - Hydrate (CSH) gel in the soil matrix. Dosage of 0.6% nano-silica is observed to be the optimum dosage. Coefficient of permeability and compression index showed an increase by 13.32 and 5.5 times respectively owing to aggregation of particles and creation of void spaces as visualized from the scanning electron micrographs. Further model foundation study and numerical parametric studies using PLAXIS 2D indicate that optimized and economic results can be obtained by varying the additive dosage with depth.

• Geomechanics and Engineering
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• v.34 no.3
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• pp.221-231
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• 2023

Biopolymer stabilization is a sustainable alternative to traditional techniques that cause a lesser negative impact on the environment during production and application. The study aims to minimize the biopolymer dosages by sizing the bio-additives to the nanoscale. This study combines the advantages of bio and nanomaterials in geotechnical engineering applications and attempts to investigate the behaviour of a low viscous biopolymer, nano sodium carboxymethyl cellulose (nCMC), to treat organic soil. Soil is treated with 0.25%, 0.50%, 0.75% and 1.00% of nano-bio additive, and its effect on the plastic behaviour, compaction characteristics, strength, hydraulic conductivity (HC) and compressible nature are investigated. The strength increased by 1.68 times after 90 days of curing at a dosage of 0.5% nCMC through the formation of gel threads connecting the soil particles that stiffened the matrix. The viscosity of 1% nCMC increased exponentially, deterring fluid flow through the voids and reduced the HC by 0.85 times after curing for 90 days. Also, beyond the optimum dosage of 0.50%, the nCMC forms a film around the soil particles that inhibits the inter-particle cohesion causing a reduction in strength. Experimental results show that nCMC can effectively substitute conventional additives to stabilize the soil.

• 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.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.811-817
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• 2000

The objectives of this study are to determine optimal operation condition of chemical coagulation with ferric chloride($FeCl_3$) and fenton reagent oxidation for effluents of a biological denitrification treatment and an existing lagoon treatment of landfill leachate, and to investigate the effect of alkalinity on fenton oxidation. In jar-tester, optimum dosage of ferric chloride for removal of COD was $1,500mgFe^{3+}/L$, removal efficiencies of $COD_{Cr}$ and $COD_{Mn}$ under this condition were about 55% and 64%, respectively. After chemical precipitation($1,500mgFe^{3+}/L$) of biological treatment effluent, optimum $Fe^{2+}/H_2O_2$ ratio of fenton oxidation was 1.5, the maximum removal efficiency of COD was about 80%, and optimum dosages of ferrous sulfate and hydrogen peroxide were $600mgFe^{2+}/L$ and $400mgH_2O_2/L$, respectively. The removal efficiency of COD was decreased as alkalinity was increased.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.9
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• pp.624-629
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• 2013

The relation between performance maintenance conditions and those cost efficiency was studied to choose an optimum operating condition in the seawater desalination pretreatment system. A hollow fiber microfiltration module, which was developed with domestic technology, was tested with the various operating conditions such as chemically enhanced backwash cycles and design dosages of a cleaning chemical. Transmembrane pressure was measured to investigate membrane fouling status and cleaning degree. In addition, economic analysis was performed to compare water production costs by the operation condition. As a result, The operation mode III, chemically enhanced backwash at once a day with 100 mg/L of sodium hypochlorite (NaOCl) was selected. The concurrent evaluation between membrane filtration performance and its economic analysis will be suitable to choose an efficient optimum condition.

• The Korean Journal of Pain
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• v.12 no.1
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• pp.48-53
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• 1999

Background: Despite the popularity of epidural bupivacaine-morphine infusions for postoperative pain management, the optimum concentrations and dosages of bupivacaine have not been determined. At present, due to the disadvantages conferred by intense motor block and the increased risk of toxicity, many trials focus on reducing bupivacaine concentration and thus the evaluation of concentrations less than 0.1% may be warranted. Methods: Forty patients having epiduro-general anesthesia for hysterectomy were randomly assigned to one of two study groups. As a mean of postoperative pain control, all received 2 mg of epidural morphine bolusly 1 hr before the end of surgery and continuous epidural infusion was started using a two-day Infusor containing 4 mg of morphine in 100 ml of 0.125% bupivacaine (Group 0.125B, n=20) or 100 ml of 0.0625% bupivacaine (Group 0.0625B, n=20). Study endpoints included visual analog scales (VAS) for pain during rest and movement, sensory change and motor blockade. They were assessed at 2, 4, 8, 16, 24, 32, 40 and 48 hrs postoperatively. Results: For VAS during rest, no significance could be found between two groups over the course of study. But for VAS during movement, the 0.125B group showed more satisfactory results especially during early postoperative periods. For the incidence of complications, the 0.125B group revealed greater frequency of sensory change (25.0%) and motor blockade (10.0%) compared with the 0.0625B group. Conclusion: This study suggests that 0.0625% bupivacaine with morphine via epidural route was sufficient for pain control during rest but it was not satisfactory during movement especially in early postoperative periods. We also recommend that careful attention to motor blockade should be paid when using 0.125% bupivacaine.