• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.1
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• pp.140-152
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• 1997

A simultaneous measurement of the wall skin friction and near-wall streamwise velocity fluctuations is performed using hot film and hot wire anemometers to investigate the relation between them. Near-wall turbulence statistics measured with a hot-wire probe are in good agreement with previous results. Turbulence properties of the wall skin friction fluctuations measured with a hot film also show fairly good agreements with those measured by others except that rms level is lower in the present study. Long-time averaged space- time correlations show that the wall skin friction is highly correlated with a turbulence structure which is tilted from the wall in the streamwise direction. Tilting angles are obtained from the phase shifts between the wall skin-friction and streamwise velocity fluctuations. The convection velocity of the near-wall streamwise velocity obtained from the space-time correlation is in good agreement with that from the direct numerical simulation database.

• Textile Coloration and Finishing
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• v.30 no.2
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• pp.141-149
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• 2018

This study aimed to investigate the efficacy of eco-friendly leather dyeing by utilizing food wastes. Natural dyeing of eel skin was attempted using onion peels which have been used commonly for natural dyeing of textile fabrics. Eel skin is a by-product from fishery processing and is used mainly for making leather products. The colorant was extracted from onion peels in boiling water, concentrated, and freeze-dried. Dyeing of eel skin was carried out to study the effects of dyeing conditions, mordant type and mordanting method on dye uptake, color change, drape stiffness and colorfastness. The optimum dyeing conditions were $60^{\circ}C$ of dyeing temperature, 60min of dyeing time at 1:100($H_2O$ 90%: ethanol 10%) of bath ratio. The onion peels produced yellowish color on eel skin. The pre-mordanting was effective than the post-mordanting. As a result of the drape stiffness measurement, the Fe-mordanted sample was somewhat stiffer comparing to other mordanted samples. The light fastness of the non-mordant dye was excellent in 3-4 grade. Drycleaning fastness and rubbing fastness showed excellent results, but fastness was not significantly improved by mordanting.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.28 no.3
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• pp.63-90
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• 2002

Quantitative measurement of melanin is the best method to evaluate whitening effect of cosmetics on human skin. However, non-invasive method to quantify human skin melanin with high precision has not been established. Whitening effect of cosmetics on the skin results in lightening of skin color. Therefore, it is reasonable to measure skin color in a reproducible manner for the assessment of whitening effect. Several Instruments or methods, such as colorimeter, mexameter, and visual assessments by experts , have been used for this purpose. In this lecture I will review the details of various assessment methods for the evaluation of whitening effect and discuss the pros and cons of each method. Then I will present briefly the results of clinical trial. Finally I will introduce new non-invasive modalities to quantify melanocytes.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.631-636
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• 2000

The experimental study concerns the characteristics of a transitional flow in a concentric annulus with a diameter ration of 0.52, whose outer cylinder is stationary and inner one rotating. The pressure drops and skin-friction coefficients have been measured for the fully developed flow of water and that of glycerine-water solution (44%) at a inner cylinder rotational speed of $0{\sim}600$ rpm, respectively. The transitional flow have been examined by the measurement of pressure drops and the visualization of flow field, to reveal the relation of the Reynolds and Rossby numbers with the skin-friction coefficients and to understand the flow instability mechanism. The present results show that the skin-friction coefficients have the significant relation with the Rossby numbers, only for laminar regime. The occurrence of transition has been checked by the gradient changes of pressure drops and skin-friction coefficients with respect to the Reynolds numbers. The increasing rate of skin-friction coefficient due to the rotation is uniform for laminar flow regime, whereas it is suddenly reduced for transitional flow regime and, then, is gradually declined for turbulent flow regime. Consequently, the critical (axial-flow) Reynolds number decreases as the rotational speed increases. Thus, the rotation of inner cylinder promotes the early occurrence of transition due to the excitation of taylor vortices.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.21 no.1
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• pp.1-18
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• 1995

We had tested the effect of amino propane sulfonic acid(APSA) on the human skin with non-invasive technique. It was tested with four parameters that were hydration, elasticity, color and skin wrinkles. In vitro culture systems, APSA stimulated the proliferation of fibroblasts bolt it didn't stimulate that of keratinocyte. Also we obtained the similar effects in the raft culture method. So we concluded that APSA affected the dermal region than the epidermal region. In clinical tests, APSA changed the skin color, pbiomechanical properties(especially elasticity) and reduced skin wrinkles of the volunteers. And we could get the better results of skin wrinkle improvement by use of Skin Visiometer than Silflo Image analysis systems.

• YAKHAK HOEJI
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• v.49 no.2
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• pp.115-121
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• 2005

In this study, the performance of a portable NIR system and a FT NIR spectrometer were compared to determine water content of hairless mouse skin. The stratum corneum parts wer e separated from the epidermal tissues by trypsin solution. NIR diffuse reflectance spectra of hairless mouse skin were acquired using a fiber optic probe. In the near infrared, water molecules show two clear absorption bands at 1450 nm from first overtone of O-H stretching and 1940 nm from the combination involving O-H stretching and O-H deformation. It was found that the variations of O-H absorption band according to water content. Partial least squares regression (PLSR) was applied to develop a calibration model. The PLS model showed a good correlation between NIR predicted value and the absolute water content of separated hairless mouse skin, in vitro. For both the portable and the FT NIR spectrometer, These studies showed the possibility of a rapid and nondestructive skin moisture measurement using NIR spectroscopy. The portable NIR spectrometer with a photodiode arrays-microsensor could be more rapidly applied for the determination of water content with comparable accuracy with the performance of a FT spectrometer .

• Toxicological Research
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• v.30 no.4
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• pp.283-289
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• 2014

Tea flavonoids and polyphenols are well known for their extraordinary antioxidant activity which is considered important for anti-aging processes in animals. This study evaluated the anti-wrinkle effects of three different kinds of tea (Camellia sinensis) water extracts (CSWEs) including green, white, and black teas using a photoaged hairless mouse model. Data showed that the CSWE-treatment greatly improved skin conditions of mice suffering from UVB-induced photoaging, based on the parameters including the skin erythema index, moisture capacity, and transepidermal water loss. In addition, the wrinkle measurement and image analysis of skin replicas indicated that CSWEs remarkably inhibited wrinkle formation. In histological examination, the CSWE-treated mice exhibited diminished epidermal thickness and increased collagen and elastic fiber content, key signatures for skin restoration. Furthermore, the reduced expression of MMP-3, a collagen-degradative enzyme, was observed in the skin of CSWE-treated animals. Interestingly, comparative data between green, white, and black tea indicated that the anti-wrinkle activity of white tea and black tea is equally greater than that of green tea. Taken together, these data clearly demonstrated that CSWEs could be used as an effective anti-wrinkle agent in photoaged animal skin, implying their extended uses in therapeutics.

• The Korea Journal of Herbology
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• v.33 no.3
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• pp.19-24
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• 2018

Objectives : Hedgehog skin is one of the animal medicines in Traditional Korean Medicine for hematochezia and hemorrhoids. In this study, we examined cytotoxicity and anti-inflammatory effects. Methods : Cytotoxicity of hedgehog skin extracts was measured by MTT assay in vitro. We investigated the inhibition of lipopolysaccharide (LPS) stimulated nitric oxide (NO) production in RAW 264.7 cells. The phosphorylation of mitogen-activated protein kinases (MAPKs) was measured by western blot. And we observed the effect of hedgehog skin extracts on the expression of IL-6 genes using real time PCR. Results : As a result of MTT assay for cytotoxicity, there were no significant differences between non-treatment group and hedgehog skin extracts treatment groups. $500{\mu}g/m{\ell}$ of hedgehog skin extracts treatment significantly decreased nitric oxide production in comparison with non-treatment in LPS-induced RAW 264.7 cells. In measurement of the phosphorylation of MAPKs using western blot analysis, LPS stimulation increased the phosphorylation of MAPKs and $500{\mu}g/m{\ell}$ of hedgehog skin extracts treatment decreased the phosphorylation of ERK1, ERK2 and p38 significantly. But there were no significant differences the phosphorylation of JNK1 and JNK2. As a result of confirmation of the IL-6 mRNA gene expression using real time PCR, IL-6 mRNA gene expressions were significantly decreased in $50{\mu}g/m{\ell}$, $100{\mu}g/m{\ell}$ and $500{\mu}g/m{\ell}$ hedgehog skin extracts treated groups by comparison with non-treatment group. Conclusion : These results could provide a mechanistic explanation for the anti-inflammatory effects of the hedgehog skin.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2903-2906
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• 2003

In this paper, we developed a multichannel acupuncture point balance measurement system that measures skin resistances at various acupuncture points to evaluate the balancing state of the meridian. The system consists of 16 channel resistance-voltage converter, signal processing part for signal amplification and filtering, A/D conversion part, micro-controller part, and data processing part. Compared to the previously developed 1 channel or 4 channel systems, it is found that the 16 channel system can measure the skin resistances of 16 acupuncture points, simultaneously, providing various clinical information such as balance and variation of the resistance value.

• Journal of Biomedical Engineering Research
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• v.18 no.1
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• pp.79-86
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• 1997

This paper describes the development of portable arousal measurement and analysis system. Skin impedance change which responds to the change of arousal level was detected by the three elctrode constant current method and separated into two components(SIR, SIL). Relationship between Nz, IRI and arousal level was studied and criteria of arousal level control was decided by the sleep study. Measured data with and without warning signal were compared and analyzed.