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FRP로 보강된 복보강 콘크리트보의 휨성능에 관한 연구
이상열 ( Lee¸ Sang-youl1 ),손병직 ( ·son¸ Byung-jik ) 한국복합신소재구조학회 2022 복합신소재구조학회논문집 Vol.13 No.5
본 연구는 ACI 등 규정에 없는 FRP 보강 콘크리트의 복보강에 대한 설계흐름도를 제시하였으며, 단보강과 복보강을 비교, 분석하였다. 다양한 파라미터 연구를 통해서 각각 단보강일 때의 이점과 복보강일 때의 이점을 분석하였다. 콘크리트의 단면이 작을수록 보강량이 클수록 복보강의 휨성능이 유리하며, 반대의 경우는 단보강이 유리한 것으로 나타났다. 콘크리트의 단면을 크게 하는 것이 FRP 보강량을 크게 하는 것보다 효과가 좋으며, 콘크리트 단면 중에서 콘크리트 높이를 크게 하는 것이 효과가 우수하게 나타났다. 콘크리트의 설계기준강도가 클수록, FRP의 탄성계수가 작을수록 단보강이 유리하며, 반대의 경우는 복보강이 유리한 것으로 나타났다. This paper presented a design flow chart for double reinforced concrete beams with FRP reinforcing bars, which is not specified in regulations such as ACI, and compared and analyzed single reinforcement and double reinforcement. Through various parametric studies, the advantages of single reinforcement and double reinforcement were analyzed. The results suggest that the smaller the cross-section of concrete and the larger the amount of FRP reinforcement, the better the flexural performance of the double reinforcement, and vice versa. Enlarging the cross-section of concrete is more effective than increasing the amount of FRP reinforcement, and increasing the concrete height of the concrete cross-sections is more effective. As the design reference strength of concrete is large and the modulus of elasticity of FRP is small, single reinforcement is advantageous, and in the opposite case, double reinforcement is advantageous.
THE GENUS OF PERIODIC LINKS WITH RATIONAL QUOTIENTS
LEE, SANG YOUL,SEO, MYOUNGSOO Cambridge University Press 2009 Bulletin of the Australian Mathematical Society Vol.79 No.2
<B>Abstract</B><P>In this paper, we prove that if <I>K</I> is any periodic link in <I>S</I><SUP>3</SUP> whose quotient link is a 2-bridge link, then one half of the degree of the reduced Alexander polynomial, the minimal genus, the free genus and the canonical genus of <I>K</I> are all the same. We also give criteria to determine whether a given periodic link has a 2-bridge link quotient and some properties of this kind of periodic link.</P>
Antimelanogenesis and skin-protective activities of Panax ginseng calyx ethanol extract
Lee, Jeong-Oog,Kim, Eunji,Kim, Ji Hye,Hong, Yo Han,Kim, Han Gyung,Jeong, Deok,Kim, Juewon,Kim, Su Hwan,Park, Chanwoong,Seo, Dae Bang,Son, Young-Jin,Han, Sang Yun,Cho, Jae Youl The Korean Society of Ginseng 2018 Journal of Ginseng Research Vol.42 No.3
Background: The antioxidant effects of Panax ginseng have been reported in several articles; however, little is known about the antimelanogenesis effect, skin-protective effect, and cellular mechanism of Panax ginseng, especially of P. ginseng calyx. To understand how an ethanol extract of P. ginseng berry calyx (Pg-C-EE) exerts skin-protective effects, we studied its activities in activated melanocytes and reactive oxygen species (ROS)-induced keratinocytes. Methods: To confirm the antimelanogenesis effect of Pg-C-EE, we analyzed melanin synthesis and secretion and messenger RNA and protein expression levels of related genes. Ultraviolet B (UVB) and hydrogen peroxide ($H_2O_2$) were used to induce cell damage by ROS generation. To examine whether this damage is inhibited by Pg-C-EE, we performed cell viability assays and gene expression and transcriptional activation analyses. Results: Pg-C-EE inhibited melanin synthesis and secretion by blocking activator protein 1 regulatory enzymes such as p38, extracellular signal-regulated kinases (ERKs), and cyclic adenosine mono-phosphate response element-binding protein. Pg-C-EE also suppressed ROS generation induced by $H_2O_2$ and UVB. Treatment with Pg-C-EE decreased the expression of matrix metalloproteinases, mitogen-activated protein kinases, and hyaluronidases and increased the cell survival rate. Conclusion: These results suggest that Pg-C-EE may have antimelanogenesis properties and skin-protective properties through regulation of activator protein 1 and cyclic adenosine monophosphate response element-binding protein signaling. Pg-C-EE may be used as a skin-improving agent, with moisture retention and whitening effects.
Preparation, Structural and Spectral Properties of Poly(2-ethynylbenzyl alcohol)
Lee, Won-Chul,Jin, Sung-Ho,Lyoo, Won Seok,Park, Jong-Wook,Lim, Kwon Taek,Kim, Sang Youl,Gal, Yeong-Soon TaylorFrancis 2009 Molecular Crystals and Liquid Crystals Vol.513 No.1
<P> A hydroxy group-containing polyacetylene, poly(2-ethynylbenzyl alcohol)[poly(EBA)] was prepared by the polymerization of 2-ethynylbenzyl alcohol by using various transition metal catalysts. This polymerization proceeded in somewhat mild manner to give in moderate yield. The instrumental analysis data on the chemical structure of poly(EBA) indicated that the present polymer have a conjugated polymer backbone system with the designed substituents. The photoluminescence peak of polymer was observed at 525 nm, which is corresponded to the photon energy of 2.36 eV and the band gap of poly(EBA) was 2.38 eV. The cyclovoltamograms of the polymer exhibited the irreversible electrochemical behaviors. It was found that the kinetics of the redox process of this conjugated polymer might be mainly controlled by the diffusion process from the experiment of the oxidation current density of polymer versus the scan rate.</P>
Physical Properties of Polymethylsilsesquioxane with UV-Curable Group for Low-Loss Optical Materials
Lee, He Seung,Choi, Seung-Sock,Lee, Hangseok,Baek, Kyung-Youl,Hong, Soon Man,Lee, Eung Chan,Lee, Jong-Chan,Hwang, Seung Sang Informa UK (TaylorFrancis) 2010 Molecular Crystals and Liquid Crystals Vol.520 No.1
Estrogen Receptor α Regulates Dlx3-Mediated Osteoblast Differentiation
Lee, Sung Ho,Oh, Kyo-Nyeo,Han, Younho,Choi, You Hee,Lee, Kwang-Youl Korean Society for Molecular and Cellular Biology 2016 Molecules and cells Vol.39 No.2
Estrogen receptor ${\alpha}$ (ER-${\alpha}$), which is involved in bone metabolism and breast cancer, has been shown to have transcriptional targets. Dlx3 is essential for the skeletal development and plays an important role in osteoblast differentiation. Various osteogenic stimulators and transcription factors can induce the protein expression of Dlx3. However, the regulatory function of ER-${\alpha}$ in the Dlx3 mediated osteogenic process remains unknown. Therefore, we investigated the regulation of Dlx3 and found that ER-${\alpha}$ is a positive regulator of Dlx3 transcription in BMP2-induced osteoblast differentiation. We also found that ER-${\alpha}$ interacts with Dlx3 and increases its transcriptional activity and DNA binding affinity. Furthermore, we demonstrated that the regulation of Dlx3 activity by ER-${\alpha}$ is independent of the ligand (estradiol) binding domain. These results indicate that Dlx3 is a novel target of ER-${\alpha}$, and that ER-${\alpha}$ regulates the osteoblast differentiation through modulation of Dlx3 expression and/or interaction with Dlx3.
Polynomial invariants for virtual marked graphs and virtual surface-link theory I
World Scientific Publishing Company 2017 Journal of knot theory and its ramifications Vol.26 No.12
<P>In this paper, we introduce a notion of virtual marked graphs and their equivalence and then define polynomial invariants for virtual marked graphs using invariants for virtual links. We also formulate a way how to define the ideal coset invariants for virtual surface-links using the polynomial invariants for virtual marked graphs. Examining this theory with the Kauffman bracket polynomial, we establish a natural extension of the Kauffman bracket polynomial to virtual marked graphs and found the ideal coset invariant for virtual surface-links using the extended Kauffman bracket polynomial.</P>
Lee, Sang-Jin,Hong, Sung-Youl,Kim, Gye-Won The Korean Society for Applied Biological Chemistr 2010 Applied Biological Chemistry (Appl Biol Chem) Vol.53 No.6
Gamma-linolenic acid methyl ester (methyl GLA) was purified from the cultures of Rhizopus oryzae KSD-815, which is a filamentous fungus and has been used to make Korean traditional alcoholic beverage. In the present study, molecular mechanisms by which methyl GLA induces apoptosis in human prostate cancer cells, LNCaP, were investigated. It was found that methyl GLA mediated-apoptosis was provoked by down-regulation of mammalian target of rapamycin (mTOR) pathway, resulting from activation of AMP-activated protein kinase (AMPK) pathway and inactivation of Akt. On the other hand, a marked increase of p38 mitogen-activated protein kinase (MAPK) phosphorylation was observed within 30 min after methyl GLA treatment. Although p38 MAPK specific inhibitor, SB203580, completely blocked caspase-9 activation but not caspase-8, p38 MAPK activation was not affected by the broad caspase inhibitor, Z-VAD-FMK, which nevertheless prevented methyl GLA-provoked apoptosis. Interestingly, interference of methyl GLA-mediated p38 MAPK with SB203580 attenuated inactivation of mTOR, independent of AMPK pathway. Results indicate that methyl GLA can independently utilize two different signaling pathways for inducing the apoptosis cascade, and p38 MAPK activation is a specific regulatory role in methyl GLA-provoked apoptosis, enhancing the action mechanisms by fermentation metabolites to regulate cell death.