• Korean Journal of Materials Research
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• v.34 no.3
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• pp.125-137
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• 2024

Composite laminates are used in a wide range of applications including defense, automotive, aviation and aerospace, marine, wind energy, and recreational sporting goods. These composite beams still exhibit problems such as buckling, local deformations, and interlaminar delamination. To overcome these drawbacks, a novel viscoelastic autoclave bonding with tapered epoxy reinforcement polyurethane films is proposed. In existing laminates, compression face wrinkling and interlaminar delamination is caused in the sandwich beam. The unique viscoelastic autoclave spunbond interlayer bonding is designed to prevent face wrinkling and absorb and distribute stresses induced by external loads, thereby eliminating interlaminar delamination in the sandwich beam. Also, the existing special reinforcement causes stress concentrations, and the core is not effectively connected, which directly affects the stiffness of the beam. To address this, a novel tapered epoxy polyurethane reinforcement adhesive film is proposed, whose reinforcement thickness gradually tapers as it enters the core material. This minimizes stress concentrations at the interface, preventing excessive adhesive squeeze-out during the bonding process, and improves the stiffness of the beam. Results indicate the proposed model avoids the formation of micro cracks, interlaminar delamination, buckling, and local deformations, and effectively improves the stiffness of the beam.

• Journal of Ginseng Research
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• v.32 no.1
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• pp.48-56
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• 2008

Chronic ultraviolet (UV) exposure is the major cause of photoaging that causes skin wrinkling, roughness, dryness, laxity, and pigmentation. Recently, increasing efforts are being made to understand the relationship between foods and skin health. Ginsenosides are present in ginseng (Ginseng Radix Rubra) extract, and are known to have biomedical properties, such as, anti-oxidant and anti-inflammatory effects. In this study, we investigated whether KTNG0345 prepared from red ginseng extracts delivered orally reduces skin wrinkling and ultraviolet B (UVB)-induced wrinkle formation in hairless mouse skin. KTNG0345 was administrated orally to the mice (5 times a week) during the period of UVB-irradiation (3 times a week) for 8 weeks at three different doses of 300 mg/kg, 500 mg/kg and 1000 mg/kg (w/v). UV doses were increased weekly by 1 MED (1MED = 75 $mJ/cm^2)$ up to 4 MED and then maintained at this level. After the 8-week administration period, it was found that orally administered KTNG0345 significantly inhibited UVB-induced wrinkle formation in a dose-dependent manner. Increases in skin thickness caused by UVB were prevented by KTNG0345. Moreover, it also significantly inhibited matrix metalloproteinases (MMP) -13 and MMP-9 expressional inductions by UVB. In addition, KTNG0345 was observed to prevent UVB-induced water loss of epidermis in hairless mouse skin. Our results demonstrate that orally administered KTNG0345 has anti-wrinkling effects in hairless mouse skin, and suggest that dietary red ginseng and herbal mixture may be considered a functional beauty food for preventing UVB-induced skin wrinkles.

• Journal of Radiation Protection and Research
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• v.37 no.1
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• pp.50-55
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• 2012

To evaluate the ability of Dongchongxiacao ($Paecilomyces$ $japonica$) extract (PJE) to protect the skin from photodamage, the gross and microscopic changes in the skin of hairless mice and PJE-treated mice exposed chronically to ultraviolet (UV) were examined. The skin of the UV-irradiated mice showed characteristic signs of photoaging, such as deep wrinkles across the back. PJE-treated mice showed a significantly decreased wrinkling score. By the 22nd week, 88.9% (i.p. with saline) or 44.4% (topical administration with cream base) of the UV-irradiated mice developed at least one tumor. PJE delayed tumor onset significantly. PJE (i.p.) was also effective in reducing the occurrence of UV radiation-induced skin tumors and reduced the number of tumors per mouse. After 22 weeks of treatment, 80.0% (i.p.) and 75.0% (topical) of the mice treated with PJE were tumor-free. Tumor multiplicity was reduced by 96.2% (i.p.) in the PJE treated groups. It is noted that skin that is chronically exposed to UV is subject to photoaging and photocarcinogenesis and regular use of PJE would prevent these photodamaging effects of UV.

• Journal of the Korean Data and Information Science Society
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• v.17 no.4
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• pp.1299-1307
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• 2006

This study investigates solving production problems in an automotive stamping plant using Finite Element (FE) analysis. The fundamentals of stamping, metal plasticity and FE analysis are developed. In this paper, we provide the basis for a simulation of the stamping of a production part, the automotive rear floorpan. On-plant factorial Design of Experiments (DoE) were simulated using the floorpan model. The accuracy of the simulations was undetermined because of variability in the DoE results. Predictions of flange shape, wrinkling and thickness show qualitative agreement with manufactured parts and indicate that simulating an industrial part is feasible.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.673-674
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• 2010

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.34-39
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• 1999

IN this study when drawing a square cup blank holder pressure necessary for flange wrinkling prevention was experimentally studied. The materials used in the experiment were SPCC and SUS304 and drawing ratio was 1.62∼2.0 Two case for lubrication condition were experimented. One was without lubricant and the other was with lubrication of high viscosity.

• Transactions of Materials Processing
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• v.9 no.4
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• pp.356-361
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• 2000

In this study, when a square cup is under drawing, blank holder pressure necessary for flange wrinkling prevention was experimentally studied. The materials used in the experiment were SPCC steel and SUS304 and the drawing ratio was 1.62∼2.0. Two cases for lubricantion condition were investigated. One was without lubricant and the other was with lubricant of high viscosity.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.820-829
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• 2003

One of the important function of skin is the protection from harmful environments. Many studies were carried out to keep the skin from wrinkling and pigmenting. Skin wrinkle and pigmentation could be caused' by the unusual disruption of connective tissue, the formation of free radicals and the radiation of ultraviolet. In this study, the extracts obtained from 23 different kinds of medicinal plants were examined whether they have inhibitory effect on tyrosinase and elastase as well as free radical scavenging effect. All the extracts examined were obtained by using 70% (v/v) ethanol at $60^{\circ}C$. It has been found that there were two medicinal plants which have positive effects matching with the purpose of this study. The extract of Ephedra sinica stapf shows an inhibitory effect on tyrosinase ($IC_{50}$ = 83.7~$\mu\textrm{g}$/ml), on elastase ($IC_{50}$ = $690{\mu}\textrm{g}$/ml), and also shows free radical scavenging effect ($IC_{50}$ = 29.6$\mu\textrm{g}$/ml). The extract of Betula platyphylla Var. shows an inhibitory effect on elastase ($IC_{50}$ = 498.1$\mu\textrm{g}$/ml), and free radical scavenging effect ($IC_{50}$ = 9$\mu\textrm{g}$/ ml). The aim of the study is to find the natural compounds which have function in skin-lightening, anti-wrinkling and anti-oxidation, with safe and active ingredients in cosmetic.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.645-658
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• 2003

We evaluated activities of various plant leaf extracts and found the availability against skin aging in the leaf extract of star fruit (Averrhoa carambola L), and developed Star Fruit Leaf Extract BG30 as an ingredient of cosmetics. Star Fruit Leaf Extract BG30 was found to show scavenging activities of reactive oxygen species and an inhibitory effect on the activity of matrix metalloproteinase-1. It showed increasing activity of type I collagen and recovery effect from damage of UV-B irradiation in human fibroblast. We performed the separation of the active principal from Star Fruit Leaf Extract BG30 to give isofurcatin 2"-Ο-$\alpha$-L-rhamnopyranoside, which showed increasing activity of type I collagen. To examine the anti-wrinkle effect of Star Fruit Leaf Extract BG30, seven volunteers applied a Star Fruit Leaf Extract BG30 1 ％ cream in double blind manner to one-side of the corner of their eye and the placebo cream to the opposite side. Clinical evaluation of wrinkling was performed every week for 5 weeks using a silicone rubber replica. A statistically significant improvement of Star Fruit Leaf Extract BG30-treated site was seen in decreased wrinkles. Star Fruit Leaf Extract BG30 results in clinically visible improvement in wrinkling when used topically for 5 weeks.

• Transactions of Materials Processing
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• v.25 no.1
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• pp.12-20
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• 2016

Press machines and dies are commonly used for 3D curved sheet forming. Using conventional die forming can cause economic problems since various modifications of the die shape are required depending on the product shape. Various types of flexible forming such as multi-point dieless forming (MDF), flexible incremental roll forming have been developed to improve the needed process flexibility. Although MDF can reduce the production cost using reconfigurable dies, it still has significant material loss. Drawbacks such as wrinkling, dimpling, and forming errors can also occur despite continuous investigations to mitigate these defects. A novel sheet forming process for 3D curved surfaces, a flexibly-reconfigurable roll forming (FRRF), has been recently proposed to overcome the economic and technical limitations of current practice. FRRF has no limitation on blank size in the longitudinal direction, and also minimizes or eliminates forming defects such as wrinkling and dimpling. Feasibility studies of FRRF have been conducted using FE simulations for multi-curved shapes and various sheet thicknesses. Therefore, the fabrication of a FRRF apparatus is required for any follow-up studies. In the current study, experiments with reconfigurable rollers were conducted using a simple design pre-FRRF apparatus prior to fabricating the full size FRRF apparatus. There are three candidates for the reconfigurable roller: a bar-type shaft, a flexible shaft, a ground flexible shaft. Among these candidates, the suitable reconfigurable roller for FRRF is determined through various forming tests.