• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.357-364
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• 1997

The objective of this study was to find optimum nonionic surfactants for clean up of soils contaminated by hydrocarbon oils. PIT(phase inversion temperature) measurements in ternary systems containing pure hydrocarbons, pure nonionic surfactants, and water were carried out and interfacial tensions were measured as a function of time for n-hexadecane oil drops brought into contact with various mixtures of nonionic surfactant and water. Batch surfactant washing experiments were performed based on the measurement, results of PIT and interfacial tension and the results showed that maximum removal of n-hexadecane occurred at the PIT of the system. For the $C_{12}E_5(C_{12}H_{25}O(CH_2CH_2O)_5H)$ system, maximum n-hexadecane removal of 73.4% occurred at the PIT of $52^{\circ}C$. In contrast, n-hexadecane removal at $25^{\circ}C$ and at $60^{\circ}C$, each corresponding to the conditions of below PIT and above PIT of the system, was found to be 57.1% and 57.0% respectively. The maximum removal of a hydrocarbon at the PIT of a system, where the hydrophilic and hydrophobic properties are balanced, was found to be due to the existence of high oil solubilization into a middle-phase microemulsion and ultralow interfacial of the order of $10^{-2}$ to $10^{-3}$ dyne/cm between middle-phase microemulsion and excess oil phase.

• Journal of Korean Academy of Dental Administration
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• v.9 no.1
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• pp.32-37
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• 2021

Many approaches to local anesthesia have been studied in dentistry. In this study, we introduce a new local anesthetic method, "Point-Inject Technique (PIT)", and compare it with traditional injection techniques. The PIT method utilizes both the vasoconstrictive and antinociceptive properties of local anesthetics as well as the application of controlled pressure during injection, reducing the time to complete anesthesia. Fifty patients were selected as the experimental group who were anesthetized using PIT, and the other 50 patients were selected as the control group using the direct injection method with a carpool syringe. The PIT group received 0.25 cartridges of 2% lidocaine with 1:100,000 epinephrine. The control group received 1.5~2 cartridges of 2% lidocaine with 1:100,000 epinephrine. Both groups were asked to mark the intensity of the pain caused by anesthesia using the Numeric Pain Rating Scale. The average time to recover from anesthesia was 40 minutes in the experimental group and 90 minutes in the control group. Additionally, 96% of the experimental group reported feeling no pain, while 78% of the control group reported having some form of pain during injection. The PIT method reduced both the reported pain scores of patients as well as time to recover from local anesthesia than the widely-used syringe injection method.

• Journal of the Korean Applied Science and Technology
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• v.37 no.6
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• pp.1738-1751
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• 2020

The skin is divided into three parts: the epidermis, the dermis, and the subcutaneous fat, and the stratum corneum, which is located at the top of the epidermis, acts as a barrier that prevents drug delivery. Nanoemulsions are known to be effective in transdermal delivery of drugs through intercellular lipids because of their unique small particle size. In this study, phase inversion temperature (PIT) nanoemulsion containing α-bisabolol was optimized using response surface methodology (RSM) for effective skin absorption of α-bisabolol. As a preliminary experiment, the 25-2 fractional factorial design method and the 23 full factorial design method were performed. Box-Behnken design was performed based on the results of the factorial design method. The content of surfactant (6.3~12.6%), co-surfactant (5.2~7.8%) and α-bisabolol (0.5~5.0%) were used as factors, and the dependent variable was the particle size of the nanoemulsion. PIT nanoemulsion optimization was performed according to the RSM results, and as a result, the optimal nanoemulsion formulation conditions were predicted to be 10.4% surfactant content, 6.3% co-surfactant content, and 5.0% α-bisabolol content. As a result of the skin absorption test, the final skin absorption rate of the PIT nanoemulsion was 35.11±1.01%, and the final skin absorption rate of the general emulsion as a control was 28.25±1.69%, confirming that the skin absorption rate of the PIT nanoemulsion was better.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.1
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• pp.21-32
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• 2016

Open-pit mines are the critical infrastructure for acquiring natural resources. Since it could be endangered by environmental and safety problems during operations, continuous monitoring is required for this type of mine. However, the domestic level management and accumulation of present state data of the topographical alteration are incurred by the development and restoration of open-pit mines relying on digital topographic maps and site surveys. Because of it, other than an expert cannot be viewed easily examines those changes information of open-pit mines in the domestic level. If the efficient management and public access of the open-pit mine is targeted, it is easy to build a web-based three-dimensional monitoring system, utilized in the space information software of open source. Therefore, we purposed on developing an open-pit mine monitoring system to support the development and restoration of the ecology-friendly environment, which could be easily monitored by the general public for those changes within terrain and environments due to operations of the mine.

• Advances in materials Research
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• v.4 no.4
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• pp.215-226
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• 2015

Experiment on roughness and micro pit defects of SUS 430 ferrite stainless steel was investigated in laboratory. The relation between roughness and glossiness with reduction in height, roll surface roughness, emulsion parameters was analyzed. The surface morphology of micro pit defects was observed by SEM, and the effects of micro pit defects on rolling reduction, roll surface roughness, emulsion parameters, lubrication oil in deformation zone and work roll diameter were discussed. With the increasing of reduction ratio strip surface roughness Ra(s), Rp(s) and Rv(s) were decreasing along rolling and width direction, the drop value in rolling direction was faster than that in width direction. The roughness and glossiness were obtained under emulsion concentration 3% and 6%, temperature $55^{\circ}C$ and $63^{\circ}C$, roll surface roughness $Ra(r)=0.5{\mu}m$, $Ra(r)=0.7{\mu}m$ and $Ra(r)=1.0{\mu}m$. The glossiness was declined rapidly when the micro defects ratio was above 23%. With the pass number increasing, the micro pit defects were reduced, uneven peak was decreased and gently along rolling direction. The micro pit defects were increased with the roll surface roughness increase. The defects ratio was declined with larger gradient at pass number 1 to 3, but gentle slope at pass number 4 to 5. When work roll diameter was small, bite angle was increasing, lubrication oil in micro pit of deformation zone was decreased, micro defects were decreased, and glossiness value on the surface of strip was increased.

• Journal of the Korean Wood Science and Technology
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• v.42 no.3
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• pp.346-355
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• 2014

Confocal reflection microscopy (CRM) was utilized to create 3-dimensional images of bordered pits and cell wall in the tracheid of Korean red pine (Pinus densiflora). Ultrastructures of torus, margo, and pit border were clearly observable in the CRM micrograph. Micrograph of cross-field pit revealed the connecting and supporting structure between tracheid and ray parenchyma cell. The CRM micrographs enabled to investigate detailed structures of tracheid cell wall such as S1, S2, S3 layers, transition layers between these layers, and microfibril (MF) orientation in S3 and S2 layers as well as complicated distribution of MF orientation around bordered pits. Not only concentric MF orientation of border thickening in the pit border was observed, but also changes in MF orientation from the cell wall to the border. From the experimental results, the CRM was thought to be a versatile microtechnique to investigate detailed structures of cell wall and bordered pit in the tracheid and cross-field pit between tracheid and ray parenchyma cell.

• Tunnel and Underground Space
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• v.34 no.1
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• pp.54-70
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• 2024

Utilization of completed open-pit for mining waste disposal is an alternative method of tailing storage facility (TSF), which can minimize the area and cost required for the installation of TSF. However, long-term tailing disposal into open-pit has a potential risk of reducing mechanical stability of surrounding rock mass by acting as an additional load. In this research, a realistic open-pit tailing disposal scenario of 60,400 hours was established based on the case of Marymia gold mine, Australia. Mechanical stability of surface pillar between open-pit and underground stope was analyzed numerically by using Sigma/W, under different stope geometry and rock mass conditions. Simulation results showed that long-term tailing disposal into open-pit can significantly increase the failure probability of surface piller. This result suggests that mechanical stability of mine geometry should be conducted beforehand of open-pit tailing disposal.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.4
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• pp.849-857
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• 1998

The purpose of this study was to investigate whether fluoride-releasing pit and fissure sealant was more effective in preventing caries than conventional non-fluoride-releasing sealant. Specimens 8mm in diameter were made from sound bovine enamel. Fluoride-releasing pit and fissure sealant(Helioseal F, Vivadent, Schaan, Liechtenstein) and non-fluoride-releasing sealant(Helioseal, Vivadent, Schaan, Liechtenstein) were applied to the specimens and artificial caries was induced. Microhardness and the depth of the carious lesion was measured. The following results were obtained: 1. In group 2, sealed with fluoride-releasing sealant, there was a 58.4% decrease in microhardness. This was significantly less than the 84.4% decrease observed in group 1, sealed with non-fluoride-releasing sealant(p<0.01). 2. The average depth of the artificial carious lesion in group 2 was $30.1{\pm}9.8{\mu}m$. In group 1, sealed with non-fluoride-releasing sealant, the lesion was significantly deeper with an average depth of $58.5{\pm}4.9{\mu}m$(p<0.01). 3. Fluoride-releasing pit and fissure sealant was more anticariogenic compared to non-fluoride-releasing sealant.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.2
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• pp.336-347
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• 2006

Pit and fissure sealants has been proven as safe and effective method of caries prevention. But improper application of pit and fissure sealant may masking the caries process in occlusal fissure. Dentists have to understand the correct and exact application method of pit and fissure sealant for he good result of caries prevention. A key factor to enhanced the effectiveness of caries prevention is retention of pit and fissure sealant. Deep penetration of material into fissure and least marginal leakage around the fissure orifice are the major concerns for dentists to achieve the successive application of pit and fissure sealants. This paper reviewed the literature on the pit and fissure sealants under the following subtitles for enhanced retention : (1) application timing, (2) Indication, (3) Occlusal prophylaxis, (4) Materials, (5) Penetration, (5) Recall check Dental profession must perform the exact application of pit and fissure sealant because this procedure is one of the most technique-sensitive one in dental field.

• Journal of Soil and Groundwater Environment
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• v.18 no.3
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• pp.93-108
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• 2013

This study is aimed to prepare the effective detail survey methods(Phase II) of abandoned metal mines through the contamination assessment for mine types and facilities in the abandoned metal mine areas. The study sites of 12 abandoned mines are located in Gyeonggi-do and Gangwon-do and those were chosen among 310 sites that the Phase II survey was conducted from 2007 to 2009 after considering the results of Phase I for abandoned mines scattered all over the country. 12 study sites were classified into four types; Type I sites only have pit mouth. Type II sites have pit mouth and mine-waste field. Type III sites have pit mouth and tailing sorting field. Type IV sites have pit mouth, tailing sorting field and concentrator(s). In forest land, paddy soil and farm land of Type I, As and Cd were showed average concentration, and Cu and Pb were high on the pit mouth area in one mines where the pit mouth was developed within 500 m. In the mines of Type II, Cu and Pb were showed average concentration too, but As and Cd were slightly high in pit mouth and mine-waste field. The mines of Type III which had grinding particle process through physical separation milling or hitting showed similar tendency with Type II. However, mines of Type IV pit mouth, mine-waste field and showed various results depending on defining the contamination sources. For example, if contamination source was pit mouth, the mixed results of Type I, II, II were showed. In tailing sorting field which was regarded as the most important source and having high mobility, however, if there were no facilities or it was difficult to access directly, field sampling was missed occasionally during phase I and phase II survey. For that reason, the assessment for tailing sorting field is missed and it leads to completely different results. In the areas of Type I mines, the concentration of heavy metals exceeded precautionary standards of soil contamination or not within 1,000 meters of pit mouth. Nickel(Ni) was the largest factor of the heavy metal contamination in this type. The heavy metals except Arsenic(As) were shown high levels of concentration in Type II areas, where pit mouth and mine-waste field were operated for making powder in upriver region; therefore, to the areas in the vicinity of midstream and downstream, the high content of heavy metals were shown. The tendency of high level of heavy metals and toxic materials contained in flotation agent used during sorting process were found in soil around sorting and tailing field. In the abandoned-pit-mouth area, drygrinding area and tailing sorting field area, the content of Cupper(Cu) and Zinc(Zn) were higher than other areas. Also, the contaminated area were larger than mine reclamation area(2,000 m) and the location of tailing sorting field was one of the important factors to estimate contaminated area.