• Journal of environmental and Sanitary engineering
• /
• v.16 no.4
• /
• pp.38-46
• /
• 2001

The purposes of this study were to examine applicability of waste egg shells as conditioning agent, to determine the optimum conditions for improving digested sludge dewaterability and to compare with before and after adding them. It estimated that the optimum conditions were dosage 30 g/L, particle size 10mesh, temp. $30^{\circ}C$, pH 7 and dewatering pressure $2.66{\pm}10^4{\;}N/m^2$. On the basis of induced optimum conditions, if adding waste egg shells in digested sludge, its specific resistance was $1.13{\pm}10^{12}{\;}m/kg$ and was low about 3 times than raw digested sludge $3.5{\pm}10^{12}{\;}m/kg $. Therefore, in view of waste recycling, it seemed that we could utilize waste egg shells as conditioning assent for improving dewaterability of digested sludge.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.13 no.9
• /
• pp.895-903
• /
• 2001

Evaporation cooling phenomena of droplets containing fire suppression agents on a hot metal surface were experimentally investigated. Solution of water containing potassium acetate (30-50% by weight) and sodium bromide (10-30% by weight) were used in the experiments, and surface temperatures were ranged from 70-116$^{\circ}C$. The evaporation time of the droplet on the heated surface was determined by using frame-by-frame analysis of the video records. It is found that the apparent evaporation time is shorter in turns of pure water, sodium bromide solution and potassium acetate solution. However, the time averaged heat flux is higher in turns of pure water, sodium bromide solution and potassium acetate solution. In-depth temperature variation of the hot metal does not occur significantly by the kinds of additive.

• Journal of Environmental Science International
• /
• v.7 no.4
• /
• pp.505-510
• /
• 1998

This study has been carried out to investigate Electrostatic Precipitator's(ESP) performance enhancement and removal efficiency of fine particle according to (NH4)2SO4injection rate. The following conclusions are derived from the these test results : 1) For plant condition cases, according to the variation of concentration agent [(NH4)2SO4]-10ppm, when inlet dust loading was 2g/m2. And when Inlet dust loading was 3g/m", that was increased to 98 19% 99.16% 99.23%, 99.58%, 2) It Is seen from thins experiments that the increasing 30ppm concentration of (NH4)2SO4 increase the collection efficiency and fine particle omission control.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.20 no.6
• /
• pp.1049-1060
• /
• 2018

Soil conditioning is one of the key factors for successfull tunnel excavations utilizing the earth pressure-balanced (EPB) shield tunnel boring machine (TBM) by increasing the tunnel face stability and extraction efficiency of excavated soils. In this study, conditioning agents are mixed with the weathered granite soils which are abundant in the Korean peninsula and the workability of the resulting mixture is evaluated through the slump tests to derive and propose the most suitable conditioning agent as well as the most appropriate agent mix ratios. However, since it is cumbersome to perform the slump tests all the time either in the laboratory or in-situ, a simpler test may be needed instead of the slump test; the fall cone test was proposed as a substitute. In this paper, the correlation between the slump value obtained from the slump test and the cone penetration depth obtained from the proposed fall cone test was obtained. Test results showed that a very good correlation between two was observed; it means that the simpler fall cone test can be used to assess the suitability of the conditioned soils instead of the more cumbersome slump test.

• Journal of Periodontal and Implant Science
• /
• v.29 no.4
• /
• pp.847-863
• /
• 1999

The present study was performed to evaluate the effect of EDTA on diseased root surfaces with regard to the removal of the smear layer, exposure of dentinal tubule openings, and demineralization of the peritubular dentin. 20 periodontally involved single rooted teeth were used. After scaling and root planing, root conditioning was carried out with 3%, 17%, and 24% EDTA solution for 20 sec., 3 min., and 5 min. respectively. Then, the specimens were rinsed with tap water for 5 min. and processed for scanning electron microscopic observation. The following results were obtained. 1. In control group which was conditioned with cotton pellets soaked with saline for 3 min., the surface showed an amorphous irregular coating. The tubule orifices seemed to be com-pressed in the direction of the curette strokes. 2. In test group which was conditioned with EDTA solution, the number of opening dentinal tubules and the extent of the dentinal tubule opening increased with time irrespective of the concentration of EDTA solution. 3. In the group which was conditioned with EDTA solution for 20 sec., the smear layer was not completely removed. 4. If the time of root conditioning is above 3 min., collagen-like fibers covering the circum tubular dentin surface were shown even in the group which was conditioned with 3% EDTA solution. In conclusion, EDTA solution was a very effective root conditioning agent like low pH root conditioning agents which had various disadvantages. Therefore, using EDTA solution, more successful periodontal regeneration could be obtained.

• Polymer(Korea)
• /
• v.31 no.3
• /
• pp.184-188
• /
• 2007

Monodisperse PMMA/HDDA polymer particles were coated via electroless Ni plating using sodium hypophosphite as a reducing agent in an acidic environment. In this study, the effects of 1) the pretreatment conditions, 2) the plating temperature, 3) the plating pH, and 4) the initial pH, control of plating bath on the variation of plating rate, surface state of plated particles and plating reproducibility were investigated. It was observed that every pretreatment steps, especially conditioning and acceleration step, were very important for obtaining uniform Ni plating and the plating rate was increased with the increase of plating temperature and pH. Moreover, the initial pH control of plating bath was critical for the plating reproducibility.

• Journal of Environmental Health Sciences
• /
• v.27 no.2
• /
• pp.17-21
• /
• 2001

The object of this study is to find out the characteristics of waste oyster shells and determine the proper dosage of powdered waster oyster shells as the conditioning agent for water treatment sludge dewatering process. The large amount of waste oyster shells which discharges from the oyster farming, occurs serious environmental hazards. However, oysters shell contain large amount(about 38% by weight) of alkaline minerals, such as calcium and magnesium and so on, this natural material is thought to have the petential ability as a good conditioning agent. The results of this study are as follows. The optimum condition for improvement of the water treatment sludge dewaterability is when 6 g of waste oyster shell powder added to 200$m\ell$ of water treatment sludge. At optimum condition, the solid contents can reach to 31.78% and the specific resistance of conditioned sludge is 0.16$\times$10$^{8}$ sec$^2$/g. However, exceeding the of powdered waste oyster shell is needed to get the effective result. Consequently, the waste oyster shell can be a recyclable material to improve the dewaterability of water treatment sludges.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.18 no.11
• /
• pp.867-873
• /
• 2006

Vertical falling liquid film is extensively used in heat and mass transfer processes of many applications, such as evaporative coolers, cooling towers, and absorption chillers. In such cases, it is required that the falling film spreads widely in the surface forming thin liquid film to enlarge contact surface. An addition of surface active agent to a falling liquid film or hydrophilic surface treatment affects the fluid physical properties of the film. Surfactant addition not only decreases contact angle between the liquid and solid surface but also changes the surface from hydrophobicity to hydrophilicity. In this study, the effects of contact angle on falling film characteristics over a vertical surface have been investigated experimentally. The contact angle is varied either by an addition of surfactant to the liquid or by hydrophilic surface treatment. It is found that the wetted area is increased and film thickness is decreased by the hydrophilic treatment as compared with those of other surfaces. With this hydrophilic treatment, the falling liquid film spreads out widely in the surface. As surfactant concentration is increased, wetted area is also increased and the film thickness is substantially decreased.

• Toxicological Research
• /
• v.30 no.4
• /
• pp.297-304
• /
• 2014

Peppermint (Mentha piperita) is a plant native to Europe and has been widely used as a carminative and gastric stimulant worldwide. This plant also has been used in cosmetic formulations as a fragrance component and skin conditioning agent. This study investigated the effect of peppermint oil on hair growth in C57BL/6 mice. The animals were randomized into 4 groups based on different topical applications: saline (SA), jojoba oil (JO), 3% minoxidil (MXD), and 3% peppermint oil (PEO). The hair growth effects of the 4-week topical applications were evaluated in terms of hair growth, histological analysis, enzymatic activity of alkaline phosphatase (ALP), and gene expression of insulin-like growth factor-1 (IGF-1), known bio-markers for the enhanced hair growth. Of the 4 experimental groups, PEO group showed the most prominent hair growth effects; a significant increase in dermal thickness, follicle number, and follicle depth. ALP activity and IGF-1 expression also significantly increased in PEO group. Body weight gain and food efficiency were not significantly different between groups. These results suggest that PEO induces a rapid anagen stage and could be used for a practical agent for hair growth without change of body weight gain and food efficiency.

• Restorative Dentistry and Endodontics
• /
• v.21 no.1
• /
• pp.136-149
• /
• 1996

The effects of various All-Etching Agents (10% phosphoric acid, 10% maleic acid and 10 % citric acid) and 32 % phosphoric acid and varied etching time were evaluated by observing the morphology of the etched enamel surfaces using Scanning electron microscopy and by measuring the shear bond strength of a composite resin to human enamel. A total of 156 extracted premolar and molar teeth free of irregularities were employed in this study. Specimens for the observation of enamel morphology were divided into 12 groups of 3 teeth each, based on the type of etchant used and application time. After exposure to the etching agent specimens were washed air-dried and then glued to aluminum stubs and coated with a layer of gold for examination in the scanning electron microscope. Specimens for the evaluation of bond strength were divided into 12 groups of 10 teeth each also based on the type of etchant used and application time. After exposure to the etching agent the specimens were washed, air-dried and a thin layer of bonding agent was applied using a brush. Z 100 composite resin was light cured to the surface and stored at $37^{\circ}C$, 100% humidity for 7 days. An Instron Universal Testing Machine was used to apply a shearing force at $90^{\circ}$ angle from the enamel surface. It is concluded from this study that commercial All-etching agents can be used with a 15-second etching without adversely affecting retention of dental resin materials. At the same time, the acid concentration is probably a suitable compromise regarding the acid's function as a dentin demineralizing all-etch conditioning agent. The following results were obtained. 1. Specimens etched with 10 % citric acid showed a random superficial etching pattern which could not be related to prism morphology. 2. Specimens etched with 10 % and 32 % phosphoric acid and 10 % maleic acid showed a type I pattern in which core material was preferentially removed leaving the prism peripheries relatively intact or a type II pattern in which prism peripheries were preferentially removed. This delineation became more distinguished as etching time was increased. 3. All-Etching Agents and 32 % phosphoric acid showed a statistically significant higher shear bond strength at 15 seconds etching time.(p<0.05) 4. 10 % maleic acid and 32 % phosphoric acid exhibited a statistically significant higher shear bond strength than 10 % phosphoric and citric acid at 15 seconds etching time.(p<0.05).