• Proceedings of the KWS Conference
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• 1996.05a
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• pp.13-14
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• 1996

High Frequency Electric Resistance Welding process has been widely used in manufacturing welded steel pipes because of its high welding speed and quality. This process utilizes the skin effect as well as the proximity effect of the high frequency current in heating the skelp edge. In this study, an analytical solution of the edge temperature was obtained based on several assumptions. The assumptions includes the expontial decay of weldingcurrent from the surface and neglect of the heat loss in the welding direction. This calculation shows a good agreement with the observations made from the high speed camera. Using tile analytical model, tile heat required as a function of the welding speed and the skelp thickness was determined. These results were compared with the experimental results obtained.

• Proceedings of the SCSK Conference
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• 1999.10a
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• pp.43-50
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• 1999

The planarized SiO$_2$ particles were prepared by two-step reduction method of making much smaller particles, micron-sized ones, to improve spreadability, adherence, and smoothness. Various pigments known as flaky extender usually have terrace layers on their surfaces, but SiO$_2$ particles in this study exhibit a smooth surface structure. These single SiO$_2$ particles were used as core particles to prepare the composite particles coated with ultra fine TiO$_2$ particles by a homogeneous precipitation method. The thickness and the morphology of the deposited TiO$_2$ layers could be modified by adjusting the reactant concentrations, the reaction time and the temperature. The characteristics of SiO$_2$/TiO$_2$ composite in the field of color cosmetics are to give an UV-cut effect and to enhance the chroma of human skin color, one of optical properties.

• Membrane Journal
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• v.6 no.2
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• pp.96-100
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• 1996

In order to improve the permeability of the homogenous membrane of poly(carbobenzoxy-L-lysin)(PCLL), which has very high selectivity of helium gas to nitrogen gas, asymmetric porous membranes of PCLL were prepared by casting from 20% solutions in dioxane and dimethylformamide(DMF), respectively. The membranes were characterized by measuring the number of the pores, the pore size distribution of the surface(the skin layer) and the thickness of the skin layer by scanning electron microscope and transmission electron microscope. The mean pore size and the pore density were lower for the membrane cast from dioxane than that from DMF, which was explained by the mechanism of the formation of the pores in the asymmetric porous membrane. The permeability coefficient observed could be roughly explained by the viscous flow through the skin layer. However, the selectivity observed was against the theory of the viscous flow.

• Archives of Plastic Surgery
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• v.44 no.5
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• pp.378-383
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• 2017

Background This study aimed to assess the effects of the topical application of tamoxifen on wound healing of burned skin in Wistar rats by evaluating 3 healing characteristics: fibrotic tissue thickness (FTT), scar surface area (SSA), and angiogenesis in the healed scar tissue. Methods Eighteen male Wistar rats were used in this study. A third-degree burn wound was made on the shaved animals' back, measuring $2{\times}2{\times}2cm$. In the first group, a 2% tamoxifen ointment was applied to the wound twice daily for 8 weeks. The second group received a placebo ointment during the same period. The third group did not receive any treatment and served as the control group. Results The median (interquartile range=[Q1, Q3]) FTT was 1.35 (1.15, 1.62) mm, 1.00 (0.95, 1.02) mm, and 1.25 (0.8, 1.5) mm in the control, tamoxifen, and placebo groups, respectively (P=0.069). However, the FTT in the tamoxifen group was less than in the placebo and control groups. The median angiogenesis was 3.5 (3.00, 6.25), 8.00 (6.75, 9.25), and 7.00 (5.50, 8.25) vessels per high-power field for the control, tamoxifen, and placebo groups, respectively (P=0.067). However, the median angiogenesis was higher in the tamoxifen group than in the control group. No significant difference was observed in the mean SSA between the tamoxifen group and the control group (P=0.990). Conclusions Local application of tamoxifen increased angiogenesis and decreased the FTT, with no change in the SSA in burned skin areas. These effects are expected to expedite the wound healing process, reducing contracture and preventing hypertrophic scar and keloid formation.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.385-394
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• 2021

In this paper, a new equation of electromagnetic wave transmission matrix was proposed to calculate the reflected power and transmitted power for the multi-layered planar lossy structure. The applied human leg was modeled as a four-layer planar structure of skin, fat, muscle and bone. The complex dielectric constant to consider the loss of each of these layers was calculated using the 4-pole cole-cole model parameter. When electromagnetic waves were incident on the skin surface, total reflected and transmitted power, and human body loss were calculated for a frequency band of 0.1 to 20.0 GHz. And for various muscle thicknesses, the power reflected only from the outermost bone and re-radiated from the skin was calculated. It was confirmed that at the muscle thickness of 3.0 mm and the frequency of 4.6 GHz the return loss was -6.13 dB, which was 3.42 dB lower than the average value.

• Progress in Medical Physics
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• v.13 no.2
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• pp.62-68
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• 2002

A muiltileaf collimator (MLC) is used as a replacement for conventional blocks. The MLC, however may not be appropriate for a fine field shaping. For the fine field shaping, conventional block can be added under the MLC. But it may significantly affect on the dosimetric characteristics such as surface dose of skin, buildup region and percent depth doses. We performed the study to evaluate the surface dose and the maximum depth dose using MLC conjunction with conventional blocks for various field sizes and energies. We confirmed the surface dose was increased by using the additional conventional block under the MLC ranging from 10 to 35.6％ according to various field sizes and radiation beam energies. The surface dose was effectively reduced by application of 2 or 3 m thickness of lead plate as electron filter.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.834-845
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• 1995

An experimental study is made in a nearly two-dimensional 90.deg. curved duct to investigate the effects of interaction between streamline curvature and mean strain on turbulence. The initial shear at the entrance to the curved duct is varied by an upstream shear generator to produce five different shear conditions ; a uniform flow (UF), a positive weak shear (PW), a positive strong shear(PS), a negative weak shear (NW) and a negative strong shear(NS). With the mean field data of the case UF, variations of the momentum thickness, the shape factor and the skin friction over the convex(inner) surface and the concave (outer) surface are scrutinized quantitatively in-depth. It is found that, while the pressure loss due to curvature is insensitive to the inlet shear rates, the distributions of wall static pressure along both convex and concave surfaces are much influenced by the inlet shear rates.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.214-220
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• 2003

Pipe jacking is a name for a method to excavate a tunnel by pushing pipe into the ground from an especial pit. Size of tunnels in this method is different from under 900mm (microtunneling) to more than 3,000mm. Method of excavation is also different from hand digging to use of any kind of tunnel boring machines such as slurry and earth pressure balance (EPB) machines. Slurry pipe jacking was firmly established as a special method for the nondisruptive construction of the underground tunnels in urban area. During the pipe jacking and microtunneling process, the jacking load is an important parameter, controlling the pipe wall thickness, need to and location of intermediate jacking station, selection of jacking frame and lubrication requirements. The main component of the jacking load is due to frictional resistance. In this paper the skin friction between pipe surface and surrounding condition also lubricant quality based on a few fundamental tests, were considered. During this study unconfined compressive strength test, dynamic friction measurement test and direct shear box test were raised for one of the largest diameter slurry pipe jacking project in Fujisawa city in Japan. It could be concluded that in slurry pipe jacking, prediction of frictional forces are mainly dependent on successful lubrication, its quality and lubricant strength parameters. Conclusions from this study can be used for the same experiences.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.4
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• pp.114-119
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• 2009

In this research, heat-acupuncture needle was coated with $Al_2O_3$ by applying a plasma spray coating method to prevent a skin burn. $Al_2O_3$, which is one of the representative bioceramics, does not have an influence on the chemical change in the body system. The ceramic coating thickness was about $100{\mu}m$. The experiments of heat conduction were performed for uncoated needle and coated needle. The results showed that the surface temperature of needle decreased as the needle was coated with $Al_2O_3$. The surface temperature of uncoated needle was about $48^{\circ}C$, while that of needle coated with $Al_2O_3$ was about $39^{\circ}C$.

• Journal of the Korean Burn Society
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• v.22 no.2
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• pp.21-24
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• 2019

Incidence of low-temperature contact burn by use of an electric pad is increased recently, especially in depressed sensory. Acquired immune deficiency syndrome patient using antiretroviral agent suffered with sensory depression as side effect. There are many limitations in wounds treatment of these patients. These patients are vulnerable to infection due to their weak immunity, so it is necessary to keep them in a state of isolation when a wound occurs. We report a case of a third degree burn by electric pad with a surface area of approximately 5% of the body surface of a patient who underwent a sensory depression, which is a side effect of antiretroviral drugs used for treatment in patients with AIDS. In this regard, we report the case with literature review, which is safely recovered using negative-pressure wound therapy and split-thickness skin graft.