• Journal of applied mathematics & informatics
• /
• v.9 no.2
• /
• pp.731-744
• /
• 2002

The temperature distribution in human skin and subdermal tissue layer is presented using bioheat transfer equation. The body temperature is determined by the balance between heat produced and heat lost by our body. The time-dependent solutions have been found to be affected by the metabolic heat generation rate, blood mass flow, the rate of evaporation of perspiration and also by the atmospheric temperature. The analytic solutions for different layers have been calculated numerically and are also shown graphically.

• Journal of applied mathematics & informatics
• /
• v.25 no.1_2
• /
• pp.67-83
• /
• 2007

The characteristics of steady two-dimensional laminar boundary layer flow of a viscous and incompressible fluid past a moving wedge with suction or injection are theoretically investigated. The transformed boundary layer equations are solved numerically using an implicit finite-difference scheme known as the Keller-box method. The effects of Falkner-Skan power-law parameter (m), suction/injection parameter ($f_0$) and the ratio of free stream velocity to boundary velocity parameter (${\lambda}$) are discussed in detail. The numerical results for velocity distribution and skin friction coefficient are given for several values of these parameters. Comparisons with the existing results obtained by other researchers under certain conditions are made. The critical values of $f_0$, m and ${\lambda}$ are obtained numerically and their significance on the skin friction and velocity profiles is discussed. The numerical evidence would seem to indicate the onset of reverse flow as it has been found by Riley and Weidman in 1989 for the Falkner-Skan equation for flow past an impermeable stretching boundary.

• Investigative Magnetic Resonance Imaging
• /
• v.10 no.2
• /
• pp.121-125
• /
• 2006

A 48-year-old man presented with a dermatofibrosarcoma protuberans (DFSP) of the scalp associated with local recurrence. Axial T1- and T2-weighted images demonstrated a well-circumscribed hypointense and intermediate hyperintense mass in the skin and subcutaneous layer of the scalp, respectively. Contrast-enhanced T1-weighted images showed the strongly enhanced mass invasion to the skin, subcutaneous layer and adjacent galeal layer. Scalp DFSP is very uncommon but is an aggressive tumor, so MR imaging diagnosis of the extent of the lesion to underlying structures, and initial wide local resection is important to prevent recurrence.

• Journal of the Korean Society of Visualization
• /
• v.3 no.1
• /
• pp.78-89
• /
• 2005

An experimental study was carried out to investigate the effect of local ultrasonic forcing on a turbulent boundary layer. Stereoscopic particle image velocimetry (SPIV) was used to probe the characteristics of the flow. A ultrasonic forcing system was made by adhering six ultrasonic transducers to the local flat plate. Cavitation which generates uncountable minute air-bubbles having fast wall normal velocity occurs when ultrasonic was projected into water. The SPIV results showed that the wall normal mean velocity is increased in a boundary layer dramatically and the streamwise mean velocity is reduced. The skin friction coefficient (C$_{f}$) decreases 60$\%$and gradually recovers at the downstream. The ultrasonic forcing reduces wall-region streamwise turbulent intensity, however, streamwise turbulent intensity is increased away from the wall. Wall-normal turbulent intensity is almost the same near the wall but it increases away from the wall. In the vicinity of the wall, Reynold shear stress, sweep strength and production of turbulent kinetic energy were decreased. This suggests that the streamwise vortical structures are lifted by ultrasonic forcing and then skin friction is reduced.

• Archives of Plastic Surgery
• /
• v.35 no.6
• /
• pp.716-722
• /
• 2008

Purpose: Split or full thickness skin graft is generally used to reconstruct the palmar skin and soft tissue defect after release of burn scar flexion contracture of hand. As a way to overcome and improve aesthetic and functional problems, the authors used the preserved superficial fat skin(PSFS) composite graft for correction of burn scar contracture of hand. Methods: From December of 2001 to July of 2007, thirty patients with burn scar contracture of hand were corrected. The palmar skin and soft tissue defect after release of burn scar contracture was reconstructed with the PSFS composite graft harvested from medial foot or below lateral and medial malleolus, with a preserved superficial fat layer. To promote take of the PSFS composite graft, a foam and polyurethane film dressing was used to maintain the moisture environment and Kirschner wire was inserted for immobilization. Before and after the surgery, a range of motion was measured by graduator. Using a chromameter, skin color difference between the PSFS composite graft and surrounding normal skin was measured and compared with full thickness skin graft from groin. Results: In all cases, the PSFS composite graft was well taken without necrosis, although the graft was as big as $330mm^2$(mean $150mm^2$). Contracture of hand was completely corrected without recurrence. The PSFS composite graft showed more correlations and harmonies with surrounding normal skin and less pigmentation than full thickness skin graft. Donor site scar was also obscure. Conclusion: The PSFS composite graft should be considered as a useful option for correction of burn scar flexion contracture of hand.

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

• Journal of the Korean Applied Science and Technology
• /
• v.36 no.2
• /
• pp.524-530
• /
• 2019

In this study, polyether polyol polypropylene glycol and isophorone diisocyanate (IPDI) were synthesized based on polyrupopylene mono methyl eher (PM) for the synthesis of water - soluble polyurethane for coating on leather skin layer. After synthesis of prepolymer, PM was added at $40^{\circ}C$ to 1M, 2M, 3M, and 4M to inhibit the viscosity rise, and neutralization reaction and chain extension reaction were carried out to prepare polyurethane samples. According to the measurement results of the tensile strength, elongation and adhesive strength of the prepared sample, the tensile strength was 2.109 kgf / mm2 for PM 1M, 1.721kgf / mm2 for 4M, elongation was 496% for PM 1M, 522% for 4M, adhesion was 1.114 kgf / cm for PM 1M and 0.99 kgf / cm for 4M.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.46 no.3
• /
• pp.107-115
• /
• 2009

Skin color detection is used to classify input pixels into skin and non skin area, and it requires the classifier to have a high classification rate. In previous work, most classifiers used single color model for skin color detection. However the classification rate can be increased by using more than one color model due to the various characteristics of skin color distribution in different color models, and the MLP is also invested as a more efficient classifier with less parameters than other classifiers. But the input dimension and required parameters of MLP will be increased when using two color models in skin color detection, as a result, the increased parameters will cause the huge teaming time in MLP. In this paper, we propose a MLP based classifier with less parameters in two color models. The proposed partially connected MLP based on two color models can reduce the number of weights and improve the classification rate. Because the characteristic of different color model can be learned in different partial networks. As the experimental results, we obtained 91.8% classification rate when testing various images in RGB and CbCr models.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.31 no.2
• /
• pp.143-149
• /
• 2005

Objects : With the advancement of tissue engineering techniques, the effort to develop bioartificial mucosa have been actively delivered. The problem we met with this technique is the lack of mechanical strength between kerationocyte layer and dermal layer, where in the normal skin and mucosa, they are tightly bound with rete ridge structure. The purpose of this study is to understand the 2D and 3D structure of rete ridge of mucosa and skin paddle for rendering more biomimetic structure to the artificial mucosa. Materials and Methods : Oral mucosa and skin from the patients who received the oral surgery and maxillofacial reconstruction were harvested. The epidermis was separated from the dermis after treating with dispase for 12-16 hours. H&E staining was performed for 2D(dimensional) structure study and confocal LASER and SEM study were performed for 3D structure. Mean height(Sc) and arithmetic mean deviation(Sa) of all surface height were calculated. Results : The average height of rete ridge of skin flap was between $67.14{\mu}m$ and $194.55{\mu}m$. That of oral mucosa was between $146.26{\mu}m$ and $167.51{\mu}m$. Pressure bearing area and attached gingiva of oral mucosa showed deeper rete ridges. Conclusion : To obtain the adequate strength of artificially cultured keratinocyte skin and mucosa flap, it is necessary to imitate the original skin and mucosa structure, especially rete ridge. Through this study, 2D and 3D rete ridge structure of normal mucosa and skin was obtained. These results can be used as basis for substrate morphology for keratinocytes culture.

• Clean Technology
• /
• v.29 no.2
• /
• pp.109-117
• /
• 2023

The purpose of this study is to develop a method for separating antioxidants and sugars from grape skin extract. The extract was first mixed with a variety of organic solvents to investigate whether the separation was feasible. When employing acetone, ethanol, dimethylsulfoxide, or dimethylformamide, the organic solvent-extract combination formed a single phase. However, when benzene, ethyl acetate, or n-hexane was added to the extract, the mixture separated into an organic and an aqueous phase and the pigments remained in the aqueous phase. On the other hand, when polyethylene glycol-2,000 (PEG-2000) and sodium citrate were added to the extract, the mixture was separated into three layers, with the majority of the flavonoids migrating to the top layer and 53% of the extract's glucose migrating to the bottom layer. The top layer had significant antioxidant activity, whereas the bottom layer showed no antioxidant activity. The glucose recovery in the bottom layer increased as the molecular weight of PEG increased and the highest recovery (67%) was observed when PEG-8,000 was added. The highest flavonoid separation was observed with PEG-2,000, followed by PEG-8,000 and PEG-400. The flavonoid separation when PEG-2,000 was added resulted in a flavonoid recovery of 48% and 0.2% from the top and bottom layers, respectively. Examining the effect of the separated solution using the agar disc diffusion method on yeast cell growth confirmed that the addition of the extract, the top, and the bottom layer did not inhibit cell growth.