• Journal of the Society of Naval Architects of Korea
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• v.58 no.4
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• pp.243-252
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• 2021

The present study aims to investigate the interaction of a wire-type turbulence stimulator and the laminar boundary layer on a flat plate by flow field measurement. For the towing tank tests, a one-dimensional Laser Doppler Velocimetry (LDV) attached on a two-axis traverse was used to measure the streamwise velocity component of the boundary layer flow in zero pressure gradient, disturbed by a turbulence stimulator. The wire diameter was 0.5 and 1.0 mm according to the recommended procedures and guidelines suggested by the International Towing Tank Conference. Turbulence development by the stimulator was identified by the skin friction coefficient, mean and Root Mean Square (RMS) of the streamwise velocity. The laminar boundary layer with the absence of the wire-type stimulator was similar to the Blasius solution and previous experimental results. By the stimulator, the mean and RMS of the streamwise velocity were increased near the wall, showing typical features of the fully developed turbulent boundary layer. The critical Reynolds number was reduced from 2.7×10⁵ to 1.0×10⁵ by the disturbances caused by the wire. As the wire diameter and the roughness Reynolds number (Rek) increased, the disturbances by the stimulator increased RMS of the streamwise velocity than turbulent boundary layer.

• Korea Journal of Cosmetic Science
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• v.2 no.1
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• pp.1-10
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• 2020

Protection mechanisms for skin damage of ultraviolet (UV) absorbers in personal care products for protection against UV are well studied, but not for hair protection. The purpose of this study is to describe and compare the changes of physical property produced in human hair by doses of the UV-B exposure causing protein degradation. To observe the change of physical properties in hair, the experimental intensity of UV-B exposure has been established on the basis of statistical data from official meterological administration as daily one hour sunlight exposure for two weeks. Polysilicone-15, ethylhexyl methoxycinnamate (OMC), and octocrylene were employed for UV-B absorber, and those were treated to hair swatch by rubbing wash through shampoo and conditioner. Bending rigidity displayed kinetically successive reduction at high doses of UV exposure up to the 8,000 s, and exhibited different level at each sample of UV-B absorber. However, the values of Bossa Nova Technologies (BNT) for shinning factor were already saturable at the 2,000 s exposure except that treated with polysilicone-15. The differential scanning calorimetry (DSC) to measure a strength of inner protein produces a successive reduction of enthalpy as like a reduction of bending rigidity upon UV exposure. Surface roughness from lateral force microscope (LFM) acquired immediately after UV exposure show a saturable frictional voltage which has been also found in a saturable BNT data as the time of UV exposure increases. Through researching the DSC and the LFM, shinning of hair was much correlated to the protein damage at the surface, and bending rigidity could be regulated by the protein structural damage inside hair. Therefore, the optimization of efficient strategy for simultaneous prevention of hair protein on the surface and internal hair was required to maintain physical properties against UV.

• Journal of Life Science
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• v.25 no.5
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• pp.523-532
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• 2015

A variety of previous pharmacological studies have suggested Liriope platyphylla (L. platyphylla) may exert beneficial biological effects on inflammation, diabetes, neurodegenerative disorder, obesity, constipation, and atopic dermatitis. In addition, hydrocolloid membranes (HCMs) have attracted attention in dermatological care, including in the treatment of scleroderma skin ulcers, cutaneous ulcers, permanent tympanic membrane perforations, pressure sores, and decubitus ulcers in the elderly. To investigate the therapeutic effects of HCM containing an aqueous extract of L. platyphylla (HCM-LP) on second-degree burn wounds, their physico-chemical properties were analyzed and the therapeutic effects were observed in SD rats after treatment with HCM-LP for 14 days. Significant declines in tensile strength (38.4%) and absorptiveness (46.3%), as well as an increase in surface roughness (38.1%) were detected in HCM-LP compared with that of HCM. In SD rats with burned skin, the wound diameter was shorter in the HCM-LP treated group than in the GZ group on post-surgical day 14, while the significant improvements in scar tissue reduction, epithelium regeneration, angiogenesis, and extracellular matrix deposition were observed in the HCM-LP-treated group during all experimental periods. Overall, these results suggest HCM-LP may accelerate the process of healing the burn injury skin of SD rats through the regulation of angiogenesis and connective tissue formation.

• Journal of the Korean Applied Science and Technology
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• v.40 no.2
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• pp.223-232
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• 2023

Oxidative stress plays a significant role in the pathogenesis of various skin conditions, resulting in cellular and tissue damage that can contribute to the development of skin tone unevenness, roughness and wrinkles. In this study, we found that Trifolium pratense L. extract (TE) attenuated oxidative-induced damage in HaCaT cells and elucidated the underlying molecular mechanism. Our finding demonstrated that TE effectively protected HaCaT cells against H₂O₂-induced cell death by inhibiting caspase-3 activation, downregulating Bax and upregulating Bcl-2, and attenuating the activation of three mitogen-activated protein kinases (MAPKs). Our results suggest that TE has remarkable cytoprotective properties against oxidative damage in HaCaT cells and could serve as a complementary or alternative approach to prevent and treat skin damage.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.4
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• pp.353-361
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• 2019

Using Fervidobacterium islandicum AW-1, keratin peptides were produced and confirmed factors related to the scalp and hair. The cytotoxicity and proliferation tests as a function of the concentration of the keratin peptide did not show toxicity and effect on the cellular proliferation in the immortalized human hair dermal papilla cell line. Hair shampoos and hair essences containing keratin peptides were produced, and conducted human patch test. Result showed no skin irritation. The shampoo and the essence were apploed to 2 groups of 30 healthy adults for 4 weeks and showed statistically significant positive results for gloss, hair loss, scalp trouble, and hair roughness by visual assessment. The scalp water content was significantly increased after 2 and 4 weeks compared to before using the shampoo or the essence. Trans-epidermal water loss (TEWL) and the sebum secretion amount in the scalp were significantly decreased after 4 weeks compared to before. The frictional force against combing before and after using the hair shampoo and the essence for normal hair tress and damaged hair tress was significantly changed. The combing force was increased for normal hair tress and decreased for damaged hair tress. In conclusion, we suggest that keratin peptides are appropriated as cosmetic ingredients to be used in hair and scalp related products.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.2
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• pp.185-198
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• 2019

Human tissue undergoes aging by the oxidant damage via structural change and its physical properties. The skin aging process is well known and many evaluations have been conducted. However, studies on hair aging were relatively few and thus care for aging hair is difficult. This study aims to fabricate an aging hair and identify anti-aging effect with known ingredient in anti-aging. First of all, physical properties of aging hair of age 60s by physiologically intrinsic factors were compared to those of the hair made by various extrinsic factors such as several chemical reactions and iteration numbers of the treatments. The extrinsic aging hair of this study relates to the less amount of lipid and to the hair of perm treated once accordingly, wherein several physical properties, preferably comprise roughness and tensile strength, present a novel concept of the intrinsic aging hair. The penetration of peptide into the aging hair was leading the extrinsic hair towards more structurally directed a younger hair. In addition to the structural change, the penetration of the peptide enhanced texture and tensile strength of the aging hair. These patterns have been also found in addition of propolis. For the first time, these qualitative studies exhibit that indeed our extrinsic aging hair well describes the anti-aging efficacy as a receptor for a cross-linker and the ingredients of human hair.