• Elastomers and Composites
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• 제54권3호
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• pp.175-181
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• 2019

The research and development of high-performance polymer materials with excellent gas barrier properties has gained considerable attention from the viewpoint of expanding their applications in various fields, including tire automobile parts and the polymer film industry. Natural rubber (NR) has been widely used as a rubber material in real-life, but its application is limited owing to its poor gas barrier properties. In this paper, we study the gas barrier properties of NR, epoxidized natural rubber (ENR), and their blend compositions by using molecular simulation. The results show that ENR-50 has superior oxygen barrier properties than those of NR. Moreover, the oxygen barrier properties of a blend of NR/ENR-50 improve with increasing volume fraction of ENR-50. The trend of improved oxygen barrier properties of NR, ENR-50, and their blend is in good agreement with experimental observations.

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.510-514
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• 2011

Photodissociation dynamics of allyl alcohol ($H_2C$=CH-$CH_2OH$) has been investigated at 205 - 213 nm along the UV absorption band by measuring rotationally-resolved laser-induced fluorescence spectra of OH radicals. Observed energy partitioning of the available energy among products at all photon energies investigated was similar and the barrier energy for OH production is about 574.7 kJ/mol from the OH yield measurements. The potential energy surfaces for the $S_0$, $T_1$, and $S_1$ excited states along the dissociation coordinate were obtained by ab initio quantum chemical calculations. The observed energy partitioning was successfully modeled by the "barrier-impulsive model" with the reverse barrier and the geometry obtained by the calculated potential energy surfaces. The dissociation takes place on the $T_1$ excited state potential energy surface with an energy barrier in the exit channel and a large portion of the photon energy is distributed in the internal degrees of freedom of the polyatomic products.

• 한국응용과학기술학회지
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• 제40권6호
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• pp.1445-1453
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• 2023

In 2022, the domestic production performance of functional cosmetics in South Korea reached 4.6 trillion won, accounting for 33.85% of the total cosmetics production. The number of functional cosmetics reviewed increased by about 7.5% from the previous year, totaling 974 items. Especially with the increasing importance of the skin barrier function due to skin sensitivity caused by various environmental pollutants, domestic cosmetic companies are showing interest in the development of new ingredients and products related to this area. This study aims to analyze academic research trends related to in vitro experiments for the development of cosmetics improving the skin barrier, to provide practical information for the cosmetic industry. The findings are as follows: Academic research mainly focused on the efficacy of natural ingredients in improving the skin barrier, but there is a significant lack of quantitative accumulation of research. For the development of skin barrier-improving cosmetic ingredients, efficacy evaluation indicators were set, including hyaluronic acid production, expression of filaggrin gene, loricrin, formation of cornified envelope (CE), and expression of ceramide synthesis enzyme genes. Moreover, effective cosmetic ingredients for improving the skin barrier included lemongrass and perilla leaf extracts, flavonoids, Lactococcus lactis subsp. lactis, Exosomelike Nanovesicles derived from apple callus, Eleutherococcus sessiliflorus, Acanthopanax sessiliflorus, Eleutherococcus gracilistylus, Acer okamotoanum extracts, Aloe vera adventitious root extract, ethanol extract of Aruncus dioicus, and organic solvent fraction of Dracocephalum argunense.

• Korean Journal of Mathematics
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• 제25권2호
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• pp.229-246
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• 2017

This paper concerns barrier option of American type where the underlying price is monitored during only part of the option's life. Analytic valuation formulas of the American partial barrier options are obtained by approximation method. This approximation method is based on barrier options along with exponential early exercise policies. This result is an extension of Jun and Ku [10] where the exercise policies are constant.

• Journal of Ginseng Research
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• 제44권6호
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• pp.799-807
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• 2020

Background: The skin acts as a barrier to protect organisms against harmful exogenous agents. Compound K (CK) is an active metabolite of ginsenoside Rb1, Rb2 and Rc, and researchers have focused on its skin protective efficacy. In this study, we hypothesized that increased expression of the serine protease inhibitor Kazal type-5 (SPINK5) may improve skin barrier function. Methods: We screened several ginsenosides to increase SPINK5 gene promoter activity using a transactivation assay and found that CK can increase SPINK5 expression. To investigate the protective effect of CK on the skin barrier, RT-PCR and Western blotting were performed to investigate the expression levels of SPINK5, kallikrein 5 (KLK5), KLK7 and PAR2 in UVB-irradiated HaCaT cells. Measurement of transepidermal water loss (TEWL) and histological changes associated with the skin barrier were performed in a UVB-irradiated mouse model and a 1-chloro-2,4-dinitrobenzene (DNCB)-induced atopic dermatitis-like model. Results: CK treatment increased the expression of SPINK5 and decreased the expression of its downstream genes, such as KLKs and PAR2. In the UVB-irradiated mouse model and the DNCB-induced atopic dermatitis model, CK restored increased TEWL and decreased hydration and epidermal hyperplasia. In addition, CK normalized the reduced SPINK5 expression caused by UVB or DNCB, thereby restoring the expression of the proteins involved in desquamation to a level similar to normal. Conclusions: Our data showed that CK contributes to improving skin-barrier function in UVB-irradiated and DNCB-induced atopic dermatitis-like models through SPINK5. These results suggest that therapeutic attempts with CK might be useful in treating barrier-disrupted diseases.

• Journal of Advanced Marine Engineering and Technology
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• 제41권4호
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• pp.337-344
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• 2017

환경 문제로 인해 기존 연료를 대체하는 천연가스의 수요가 증가하고 있다. 이에 따라, 액화천연가스 운반선의 화물창이 거대화되면서 화물창 내의 슬로싱 하중이 증가하게 된다. 액화천연가스 화물창의 종류 중 하나인 Mark-III 타입의 1차 방벽은 액화천연가스와 직접적으로 접촉하고 있으며 슬로싱 하중 및 액화천연가스의 자중을 받는다. 슬로싱 하중에 의해 다양한 범위의 하중이 1차 방벽에 지속적으로 작용하며 이로 인해 피로 파괴를 유발할 수 있다. 따라서 본 연구에서는 Mark-III 타입의 1차 방벽을 포함한 단열시스템을 유한요소 모델로 구성하였으며 1차 방벽에 대해 피로수명을 평가하여 피로 특성을 확인하였다. 수치해석을 통해 주응력 범위 및 최대 주응력이 발생하는 위치를 계산하였으며 이를 통해 1차 방벽의 피로수명을 수치적으로 평가하였다. 또한, 다양한 단열시스템 타입에 대해 모델링을 실시하였으며, 피로수명 평가 결과를 통해 1차 방벽의 피로 파괴 안전성을 확보하는 최적의 단열시스템에 대해 제안하였다. 본 연구의 결과는 Mark-III 타입 1차 방벽의 피로 기반 설계에 있어 활용가치가 있을 것으로 판단된다.

• Macromolecular Research
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• 제17권9호
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• pp.682-687
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• 2009

Nanofibrous membranes of poly(D,L-lactic acid)/chitin blend were prepared by electro spinning for a barrier of guided tissue regeneration. A miscible solution was obtained by the blending chitin-salt complex into 1-methyl-2-pyrrolidone solution of poly(D,L-lactic acid). The properties of the blend were examined for nanofibrous fabrication. The viscosity of the blend solution was increased significantly due to chain entanglement despite the low ratio of chitin to poly(D,L-lactic acid). An interaction between two polymeric compositions was confirmed by Fourier transform infrared spectroscopy. X-ray diffraction detected an appreciably ordered microstructure in the nanofiber of the blend. A membrane of thinner nanofibers was fabricated by electro spinning the chitin blend. The permeability of the membranes was examined using bioactive model compounds.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.530-533
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• 2007

Our country occurs yearly damage, because of every year in the summer season characteristic localized torrential downpour. Therefor, we will research damage instance and natural calamity reduction effective plan through research against a landslide relation Debris Barrier, And the Debris Barrier decide suitability of Mountains among the Kangwon.

• 대한화장품학회지
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• 제45권3호
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• pp.225-235
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• 2019

레몬그라스와 자소엽 추출물은 다양한 생리 효과를 나타내는 것으로 알려져 있지만, 피부보습과 피부장벽에 미치는 영향은 아직까지 연구되지 않았다. 본 연구에서는 레몬그라스와 자소엽 추출물의 피부보습과 피부장벽에 미치는 영향과 페놀성 화합물을 분석하였다. 피부각질형성세포에서 각 추출물이 피부보습에 미치는 영향을 조사한 결과, 두 추출물 모두 물보다 에탄올 추출물에서 히알루론산 생성이 많았다. HPLC를 이용한 19종 페놀성 화합물 분석 결과는 레몬그라스 에탄올 추출물(CCE)에서 chlorogenic acid와 p-coumaric acid가 검출되었으며 자소엽 에탄올 추출물(PFE)에서 rosmarinic acid와 caffeic acid가 검출되었다. 피부보습에 관련된 HAS1, HAS2, HAS3 및 AQP3와 피부장벽에 관련된 filaggrin, loricrin 발현은 PFE보다 CCE에서 높았다. 또한, CCE, PFE 모두 피부보습과 표피분화 조절에 관여하는 $PPAR-{\alpha}$ 단백질의 발현이 농도 의존적으로 증가하였으며 CCE의 주요성분인 chlorogenic acid와 p-coumaric acid가 $PPAR-{\alpha}$ 발현을 증가시켰다. 결론적으로 피부보습과 피부장벽보호 효과에 있어서 CCE가 PFE보다 우수한 효과를 나타내었고, 두 추출물은 피부보습과 피부장벽개선에 대한 기능성 소재로써 활용될 수 있을 것이라 생각된다.

• 한국환경복원기술학회지
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• 제13권4호
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• pp.42-51
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• 2010

The purpose of this study is to analyze the characteristics of environment-friendliness of Root Barrier materials based on comprehensive experiments on harmfulness of Root Barrier materials and fish toxicity of Oryzias latipes mortality to verify eco-toxicity of each method of construction and Root Barrier material, which are to be applied by taking eco-toxicity into account when building ecological flows in upper areas on natural and artificial grounds. As a result, the following conclusions have been reached in this study: 1. In regard of the harmfulness analyzed, each material showed a different result of analytical value in each lab tank. Compared to lab tank, pH (la), DO (lb), T-N (VI) and T-coli (la) were in the same grade, but COD, SS, T-P and F-coli were less than that of control, respectively increased or decreased by material were analyzed. 2. In the experiment of fish toxicity, Barrier sheet was found to have 66.7% of fish mortality, indicating strong fish toxicity. Synthetic rubber system root barrier sheet (20.0%) was analyzed to have medium fish toxicity, while Synthetic resin system root barrier-waterproof sheet (3.3%), Synthetic rubber system membrane root barrier sheet (3.3%) and Synthetic resin system root barrier sheet (0.0%) showed relatively lower mortality and fish toxicity. To sum up such results as found in the experiment mentioned so far, the values of harmfulness and root penetration resistance analyzed were different in each lab tank, but there was absolutely little correlation with the mortality gained from the experiment on fish toxicity. In the experiment of fish toxicity, environment-friendly root barrier materials were analyzed, and it was found that Synthetic resin system root barrier sheet, Synthetic resin system root barrier waterproof sheet and Synthetic rubber system membrane root barrier sheet are highly environment-friendly. In contrast, Synthetic rubber system root barrier sheet was found to have medium-level environment-friendliness. Also, Barrier sheet was analyzed to have low environment-friendliness.