• 한국전산유체공학회지
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• 제20권3호
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• pp.62-69
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• 2015

Pressure change inside cabin as well as in tunnel has been calculated to assess the passenger pressure comfort of high-speed train. $C-STA^{TM}$, a CFD program based on axi-symmetric Navier-Stokes equation and Roe's FDS has been used to simulate the pressure change in tunnel during a high-speed train passing through it. To present the relative motion between the train and the tunnel, a modified patched grid scheme based on the structured grid system has been employed. The simulation program has been validated by comparing the simulation results with field measurements. Extensive parametric study has been conducted for various train speed, tunnel cross-sectional area and tunnel length to the pressure change in cabin. KTX-Sancheon(KTX2) high-speed train has been chosen for simulation and the train speed have been varied from 200 km/h to 375 km/h. The tunnel length has been varied from 300 m to 7.5 km and tunnel area from $50m^2$ to $120m^2$. Total 504 simulations have been conducted varying the parameters. Based on the database produced from the parametric simulations, minimum tunnel cross-sectional area has been surveyed for various train speeds based on Korean regulation on pressure change in cabin.

• Bulletin of the Korean Chemical Society
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• 제29권3호
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• pp.595-598
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• 2008

Emodin (3-methyl-1,6,8-trihydroxyanthraquinone) is a natural chemotherapeutic compound with diverse biological properties including an antitumor activity. Emodin, a specific inhibitor of the protein tyrosine kinase, has a number of cellular targets in related to it. Its inhibition activity affects the mammalian cell cycle regulation in specific oncogene. Practically, it has been proven to inhibit HER-2/neu tyrosine kinase expressing breast cancer cells as an anticancer agent. 2-[123I]iodoemodin has been synthesized and evaluated human breast cancer cells (MDA-MB-231, MCF-7, fibroblast as a control) which express basal levels of HER-2/neu tyrosine kinase to investigate its suitability as a breast cancer imaging agent and 2-iodoemodin has been synthesized as a standard compound. The radiochemical yield of the 2-[123I]iodoemodin was about 72% and its radiochemical purity was over 97% after purification. The radioactivity of the 2-[123I]iodoemodin was increased in a time dependent manner in both cell lines and the ratio of MDA-MB-231 and MCF7 to fibroblast was 2.9 and 1.7, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.234-235
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• 2007

Transparent nanosized $TiO_2$ sol has been made by sol-gel method, using Titanium(IV) isopropoxide precursor. To promote hydrolysis for titania is needed excess water, Oil bath and temperature about $80^{\circ}C$. $TiO_2$ sol is peptized ranging from pH 1 to 1.5 using hydrochloric acid for the stability of sol during a condensation reaction. The average particle size of $TiO_2$ sol was approximately 20nm. $TiO_2$-sillane sol was synthesized by surface treatment using MTMS to the $TiO_2$ sol. TEM analysis has been used to check the degree of dispersion and FT-IR analysis has been used to see if the sillane has been chemically bonded on the surface of $TiO_2$.

• Bulletin of the Korean Chemical Society
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• 제19권4호
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• pp.457-462
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• 1998

A chiral pentadentate bis-amide ligand, 1,9-bis(S)-pyrrolidinyl-2,5,8-triazanonane-1,9-dio ne$(S,S-prodienH_2)$ has been synthesized from the reaction of bis(2-aminoethyl)amine(dien) and S-proline, and the structure of $[Co(S,S-prodien)H_2O]ClO_4$ has be en determined by single crystal X-ray diffraction. The geometrical structure of the Co(III) complex has been an αβ -form, where the dien moiety of ligand chelates to a facial in metal center, and the aqua ligand coordinates a cis site to the secondary nitrogen of dien. The Co-N(1), Co-N(3) distances of two amide moiety in S,S-prodien are shorter than the other Co-N(2), Co-N(4), and Co-N(5) distances because of the increased basicity of nitrogen in amide. The complex crystallizes in the monoclinic space group $P2_1$(#4), with a=7.838(1), b=12.675(1), c=9.710(1) Å, β=100.39(1) and z=2. Refinement gives the final R and $R_w$ values of 0.045 and 0.057, respectively for 2130 observed reflections. Based upon the CD and X-ray data, it is identified that the absolute configuration of the αβ -$[Co(S,S-prodien)H_2O]ClO_4$ has a Λ-form.

• Journal of Microbiology and Biotechnology
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• 제32권9호
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• pp.1073-1085
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• 2022

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has continued for over 2 years, following the outbreak of coronavirus-19 (COVID-19) in 2019. It has resulted in enormous casualties and severe economic crises. The rapid development of vaccines and therapeutics against SARS-CoV-2 has helped slow the spread. In the meantime, various mutations in the SARS-CoV-2 have emerged to evade current vaccines and therapeutics. A better understanding of SARS-CoV-2 pathogenesis is a prerequisite for developing efficient, advanced vaccines and therapeutics. Since the outbreak of COVID-19, a tremendous amount of research has been conducted to unveil SARS-CoV-2 pathogenesis, from clinical observations to biochemical analysis at the molecular level upon viral infection. In this review, we discuss the molecular mechanisms of SARS-CoV-2 propagation and pathogenesis, with an update on recent advances.

• 대한화장품학회지
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• 제37권3호
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• pp.237-245
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• 2011

본 연구에서는 차가버섯 추출물의 주름개선 화장품 원료로의 가능성을 확인하기 위하여, 차가버섯의 70 % 에탄올 추출물을 제조하여, DPPH (1,1-diphenyl-2- picrylhydrazyl) radical 소거능, 엘라스타제 저해능, MMPs (matrix metalloproteinases) 발현 저해 및 HAS-2 (hyaluronan synthase-2) 발현 저해 효능을 측정하였다. 차가버섯 추출물 및 함유성분에 대한 DPPH radical 소거능과 엘라스타제 저해 효능을 측정한 결과, 차가버섯 추출물은 농도 의존적으로 DPPH radical 소거능 및 엘라스타제 저해 효능을 보였으며($SC_{50}$ = 91 ${\mu}g$/mL, $IC_{50}$ = 124 ${\mu}g$/mL), 함유성분 중 Gallic acid가 가장 우수한 결과를 나타내었다. MMPs 발현능 평가에서, 차가버섯 추출물은 5 ~ 25 ${\mu}g$/mL의 농도에서 50 ~ 79 % MMP-1 mRNA 발현을 저해하였으며 MMP-2의 발현량을 측정한 결과, 10 ${\mu}g$/mL에서 약 20 %를 감소시켰다. MMP-9의 발현에서도 5 ~ 25 ${\mu}g$/mL의 농도에서 54 ~ 70 %의 저해 효과를 나타내었다. 또한 HAS-2의 mRNA 발현량을 측정한 결과, 차가버섯 추출물이 전 농도에서 농도 의존적으로 HAS-2 발현량을 증가시켰다. 상기 결과를 종합해 볼 때 차가버섯 추출물은 주름개선 화장품 소재로서 개발이 가능할 것으로 사료된다.

• 한국철도학회논문집
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• 제2권2호
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• pp.1-5
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• 1999

Based on the development of designed technology for aluminum carbody. the prototype aluminum carbody has been constructed. All extrusion profiles required for the carbody has been produced and their quality has also been proven. For sound construction. welding technology to join aluminum extrusion profiles has been developed and jigs for precise assembly of blocks have been made. The aluminum carbody for urban subway train has been completed with the required chamber being set and the welding deformations being constrained by jigs. The safety of the carbody structure has also been proven by the static load test. And also, painting technology has been developed and the surface of the carbody has been pre-treated and painted. The developed technology to construct the aluminum carbody can be used in mass production of aluminum cars ordered by domestic and foreign customers.

• Geomechanics and Engineering
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• 제23권5호
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• pp.455-466
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• 2020

This paper presents analysis of the interaction between tunnel and Qanat with a particular interest for the optimization of Qanat shape using the discrete element code, PFC2D, and the results will be compared with the FEM results of PLAXIS2D. For these concerns, using software PFC2D based on Discrete Element Method (DEM), a model with dimension of 100m ^⁎ 100 m was prepared. A circular tunnel with dimension of 9 m was situated 20 m below the ground surface. Also one Qanat was situated perpendicularly above the tunnel roof. Distance between Qanat center and ground surface was 8 m. Five different shapes for Qanat were selected i.e., square, semi-circular, vertical ellipse, circular and horizontal ellipse. Confining pressure of 5 MPa was applied to the model. The vertical displacement of balls situated in ground surface was picked up to measure the ground subsidence. Also two measuring circles were situated at the tunnel roof and at the Qanat roof to check the vertical displacements. The properties of the alluvial soil of Tehran city are: γ_dry=19 (KN/㎥), E= 750 (kg/㎠), ν=0.35, c=0.3(kg/㎠), φ=34°. In order to validate the DEM results, a comparison between the numerical results (obtained in this study) and analytical and field monitoring have been done. The PFC2D results are compared with the FEM results. The results shows that when Qanat has rectangular shape, the tensile stress concentration at the Qanat corners has maximum value while it has minimum value for vertical ellipse shape. The ground subsidence for Qanat rectangular shape has maximum value while it has minimum value for ellipse shape of Qanat. The vertical displacements at the tunnel roof for Qanat rectangular shape has maximum value while it has minimum value for ellipse shape of Qanat. Historical shape of Qante approved the finding of this research.

• 대한화장품학회지
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• 제39권4호
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• pp.281-288
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• 2013

히알루론산(HA)은 피부의 세포외기질을 구성하는 주성분이다. 인간의 피부에서 히알루론산의 양은 노화와 함께 감소되는 것으로 보고되어 있으며, 이것은 노화에 따른 피부 수분 감소, 주름 형성 및 피부 탄력 저하에 관여한다고 알려져 있다. 지금까지 밝혀진 히알루론산 합성효소(hyaluronan synthase, HAS)들 중에 HAS-2가 사람의 피부 섬유아세포에서의 히알루론산의 합성을 조절하는 것으로 알려져 있다. 본 연구에서는 천궁으로부터 분리된 ferulic acid가 사람의 피부 유래 섬유아세포에서 히알루론산의 생성에 미치는 효과를 확인하였다. Semi-quantitative RT-PCR과 quantitative real-time PCR을 통해 ferulic acid가 HAS-2의 발현을 증가시키는 것을 확인하였으며 ELISA assay를 통해 ferulic acid가 히알루론산의 생성을 증가시키는 것을 확인하였다. 결론적으로 본 연구를 통해 ferulic acid는 피부 노화에 따른 히알루론산의 감소에 의해 나타나는 건조, 주름 및 탄력 저하와 같은 현상을 개선시킬 가능성을 가진 물질임을 확인하였다.

• 한국세라믹학회지
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• 제26권2호
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• pp.221-227
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• 1989

To investigate the development and densification YBa2Cu3O7-x(1-2-3) superconducting phase, the 1-2-3 phase powders have been prepared by citrate and nitrate processes with changing calcination temperature. Nearly pure 1-2-3 phase peaks have been obtained by calcining the precursor in air at 90$0^{\circ}C$ for 2.5h in citrate process but at 95$0^{\circ}C$ for 2.5h in nitrate process. The sintering density of citrate derived sample calcined at 80$0^{\circ}C$ has been about 4% higher than that calcined at 90$0^{\circ}C$, although the compacting density has been lower at 80$0^{\circ}C$ calcination. This can be explained that the 1-2-3 phase particles formed at 80$0^{\circ}C$ have reactive sub-micron size which has good sinterbililty.