• Archives of Pharmacal Research
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• v.19 no.3
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• pp.183-190
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• 1996

There are a wide variety of semi-solid ointments used for healing the skin diseases, whose therapeutic and skin penetration abililties may greatly differ from one another depending on the compositions of ointment vehicles. A computer optimization technique was applied to obtain the optimum formula of o/w type ointment giving the in vitro maximum absorption rate through hairless rat skin membrane. Some of the formulations were selected to find out a relationship between skin penetration of ointment and its Theological characteristics. The experimental value of absorption rate obtained from the ointment by optimum formula agreed well with the theoretical value obtained from a polynomial regression analysis, Three kinds of ointments selected among 15 formulations were obtained with a concentric cylinder type rheometer (Model; Rheolab SM-HM Physica, Germany) at 20, 30, 40 and $50^{\circ}C$ for rheograms of rhelolgical properties of o/w type ointments. As the temperature was raised, all products showed a decrease in both shear stress and yield values. The higher skin penetration, the lower shear stress showed.

• Journal of the Korean institute of surface engineering
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• v.54 no.2
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• pp.62-70
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• 2021

Al2024 aluminum alloy specimens were exposed to atmospheric conditions for maximum 24 months and analyzed by electron microscopes to characterize their corrosion behavior and oxide film characteristics. As the exposure time increased from 12 months to 24 months, the number of pitting sites per 1 mm² increased from ~100 to ~200. The uniform oxidation (or non-pitting) region of the 12-month exposure specimen showed 30~120 nm thick oxide layer, whereas the 24-month exposure specimen showed 170~200 nm thick oxide with the local oxygen penetration region up to 1 ㎛ deep. There was no local corrosion area observed in the 12-month exposure specimen except pitting. However, in the 24-month exposure specimen, local oxygen penetration region was observed beneath the uniform oxide layer and near the pitting cavity. Al2024 showed two times thicker uniform oxide layer but much shallower local oxygen penetration region than Al1050, which appears to be related to low Si concentration. Further research is needed on the effects of Mg segregation near the tip of the oxygen penetration region.

• Journal of Electrochemical Science and Technology
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• v.12 no.4
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• pp.440-452
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• 2021

Enhancement of durability and reduction of maintenance cost of concrete, with the implementation of various approaches, has always been a matter of concern to researchers. The integration of pozzolans as a substitute for cement into the concrete is one of the most desirable technique. Silica fume (SF) and colloidal nanosilica (CS) have received a great deal of interest from researchers with their significant performance in improving the durability of concrete. The synergistic role of the micro and nano-silica particles in improving the main characteristics of cemented materials needs to be investigated. This work aims to examine the utility of partial substitution of cement by SF and CS in binary and ternary blends in the improvement of the durability characteristics linked to resistance for electrochemical corrosion using electrical resistivity and half-cell potential analysis and chloride penetration trough rapid chloride penetration test. Furthermore, the effects of this silica mixture on the compressive strength of concrete under normal and aggressive environment have also been investigated. Based on the maximum compression strength of the concrete, the optimal cement substituent ratios have been obtained as 12% SF and 1.5% CS for binary blends. The optimal CS and SF combination mixing ratios has been obtained as 1.0% and 12% respectively for ternary blends. The ternary blends with substitution of cement by optimal percentage of CS and SF exhibited decreased rate for electrochemical corrosion. The strength and durability studies were found in consistence with the microstructural analysis signifying the beneficiary role of CS and SF in upgrading the performance of concrete.

• Journal of the Korean institute of surface engineering
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• v.55 no.5
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• pp.273-283
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• 2022

Al6061 aluminum alloy specimens were exposed to atmospheric conditions for maximum 24 months. 24-month exposure specimen showed some more frequent and larger size of corrosion products and pitting on the surface compared with the 12-month exposure specimens. The XRD examination revealed the dominant surface oxide phases of Al₂O₃ and Al(OH)₃. The oxide thickness at uniform oxidation (or non-pitting) region was not much changed over exposure time. The 1.2 ㎛ deep oxygen penetration area was found in the 12-months exposed specimen near the thin uniform aluminum oxide film. The line-EDS was conducted through the penetration regions and non-penetrated grain boundary. There were signs of O and Si concentration through the penetration region, whereas non-penetration region showed no concentration of O or Si. It was confirmed that pitting is a more severe degradation mode in Al6061 (max. >4 ㎛ deep) compared with the uniform oxidation (max. ~200 nm deep) up to 24-months exposure.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.699-717
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• 2016

This study was carried out to investigate the effect of no-tillage on sequential cropping supported from recycling of first crop ridge on the growth of pepper plant and physical properties of soil under green house condition. 1. Degree of crack on soil by tillage and no-tillage Soil cracks found in ridge and not found in row. At five months of tillage, crack number and crack length in length ridge were 3 and 37~51 cm in tillage. Maximum width and maximum depth in length ridge were 30 mm and 15.3cm in tillage. Crack number and crack length in width ridge were 7.5 and 7~28 cm in tillage. Maximum width and maximum depth in width ridge were 29 mm and 15.3 cm in tillage. At a year of no-tillage, crack number and crack length in length ridge were 1.0 and 140~200 cm in tillage. Maximum width and maximum depth in length ridge were 18 mm and 30 cm in a year of no-tillage. Crack number and crack length in width ridge were 11 and 6~22 cm in a year of no-tillage. Maximum width and maximum depth in width ridge were 22 mm and 18.5 cm in a year of no-tillage. Soil crack was not found at 2 years of no-tillage in sandy Jungdong series (jd) soil. Soil crack was found at 7 years of no-tillage in clayish Jisan series (ji) soil. 2. Penetration resistance on soil Penetration resistance was increased significantly at no-tillage in Jungdong series (jd). Depth of cultivation layer was extended at no-tillage soil compared with tillage soil. Penetration resistance of plow pan was decreased at 1 year of no-tillage compared with than tillage soil. Penetration resistance was linearly increased with increasing soil depth at tillage in Jisan series (ji). Penetration resistance on top soil was remarkably increased and then maintained continuously at no-tillage soil. 3. Drainage and moisture content of soil Moisture content of ridge in top soil was not significant difference at both tillage and no-tillage. Moisture content of ridge in 20 cm soil was 14% at no-tillage soil and 25% at tillage soil. 4. Change of capacity to retain water in soil Capacity to retain water in top soil was not significant difference at 1 bar both tillage and no-tillage. Capacity to retain water in soil was slightly higher tendency in 1 year and 2 years of no-tillage soil than tillage soil. Capacity to retain water in soil was increased at 15 bar both tillage and no-tillage. Capacity to retain water in subsoil was slightly higher tendency at 1 bar and 3 bar in 2 years of no-tillage than tillage soil and a year of no-tillage soil.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.3
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• pp.265-273
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• 2019

This study was performed to evaluate clinical use of laser fluorescence (LF) to identify early childhood caries lesions suitable for applying resin infiltration. 20 exfoliated primary molars with proximal caries were selected and cut buccolingually cross the central pit for regarding the mesial and distal surfaces respectively. 27 specimens corresponding to ICDAS code 1 and 2 were selected and the LF values were measured. When infiltrant resin was applied, double staining for microscopy detection has done simultaneously. Tooth samples were sliced with 0.7 mm thick. The maximum lesion depth, maximum penetration depth, and average penetration rate were measured from the confocal scanning laser microscope image. Pearson correlation analysis was performed. The intraclass correlation coefficient of LF values shows excellent agreement. LF values had positive correlation with penetration rate, but not lesion depth and penetration depth. Significant correlation between LF readings and penetration rate was verified in deep enamel caries and dentin caries except shallow enamel caries. Infiltrant resin could penetrate with a higher rate and LF values could be increased in more active caries lesions. In assessing radiologically similar caries lesion, laser fluorescence might be useful for identifying caries activity.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.387-394
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• 2001

An apparent earth pressure envelope for anchored walls proposed by FHWA was compared with Terzaghi & Peck's earth pressure envelope. The anchor design load, the maximum bending moment and the penetration depth were calculated by a simple beam analogy method for each type of envelope.

• Radiation Oncology Journal
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• v.1 no.1
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• pp.29-36
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• 1983

The treatment of tumors along curved surfaces with stationary electron beams using cone collimation may lead to non-uniform dose distributions due to a varying air gap between the cone surface and patient. For large tumors, more than one port may have to be used in irradiation of the chest wall, often leading to regions of high or low dose at the junction of the adjacent ports. Electron-beam arc therapy may elimination many of these fixed port problems. When treating breast tumors with electrons, the energy of the internal mammary port is usually higher than that of the chest wall port. Bolus is used to increase the skin dose or limit the range of the electrons. We invertiaged the effect of various arc beam parameters in the isodose distributions, and combined into a single arc port for adjacent fixed ports of different electron beam eneries. The higher fixed port energy would be used as the arc beam energy while the beam penetration in the lower energy region would be controlled by a proper thickness of bolus. We obtained the results of following: 1. It is more uniform dose distribution of electron to use rotation than stationary irradiation. 2. Increasing isocenter depth on arc irradiation, increased depth of maximum dose, reduction in surface dose and an increasing penetration of the linear portion of the curve. 3. The deeper penetration of the depth dose curve and higher X-ray background for the smaller field sized. 4. If the isocenter depth increase, the field effect is small. 5. The decreasing arc beam penetration with decreasing isocenter depth and the isocenter depth effect appears at a greater depth as the energy increases. 6. The addition of bolus produces a shift in the penetration that is the same for all depths leaving the shape of the curves unchanged. 7. Lead strips 5 mm thick were placed at both ends of the arc to produce a rapid dose drop-off.

• Journal of Conservation Science
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• v.29 no.3
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• pp.243-247
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• 2013

This study was conducted to investigate the penetration of PEG for conservation treatment conditions of archaeological waterlogged wood. The weight percent gain was examined, depending on the solvent of PEG, concentration and treatment period and temperature of treatment solutions. The penetration of PEG in the cell lumina of treatment woods was observed by scanning electron microscope. The results showed that the type of solvents had no influence on PEG penetration. In the concentration of the PEG treatment solutions, the weight percent gains (WPGs) were increased with increase in concentration of PEG. In terms of the period of the soaking treatment, a maximum WPGs were obtained for only 20 days. There was no distinctive difference in the WPGs by difference the temperature of the treatment. In conclusion, in the conservation of small size of archaeological waterlogged wood, it is confirmed that optimal solvent type and treatment period of PEG are water and 20 days, respectively.

• Biomolecules & Therapeutics
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• v.14 no.2
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• pp.90-95
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• 2006

CKD-602 exerts its antitumor effect via inhibition of topoisomerase I in cancer cells. Multicellular spheroid (MCS) and Multicellular layers (MCLs) are known as in vitro 3-dimensional models which closely represent tumor conditions in vivo. In order to investigate the potential of CKD-602 against human colorectal tumors, we evaluated the anti-proliferative activity and penetration ability of CKD-602 in MCS and MCL cultures of DLD-l human colorectal cancer cells, respectively. The maximum effects($E_{max}$) induced by CKD-602 were significantly lower in MCS compared to monolayers (48% vs 92%). With prolonged drug exposure, the $IC_{50's}$ of CKD-602 decreased to $23.5{\pm}1.0nM$ in monolayers after 24 h exposure and $42.3{\pm}1.7nM$ in MCS after 6 days, respectively. However, no further increase in effect was observed for exposure time longer than growth doubling time (Td) in both cultures. Activity of CKD-602 was significantly reduced after penetration through MCL and also with cell-free insert membrane. In conclusion, CKD-602 showed significantly decreased anti-proliferative activity in 3D cultures (MCS) of human colorectal cancer cells. Tumor penetration of CKD-602 could not be determined due to loss of activity after penetration through cell free insert membrane, which warrants further evaluation using a modified model.