• 생명과학회지
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• 제24권7호
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• pp.798-803
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• 2014

Cathepsin D (CtsD)는 아스파르트산 단백질 분해효소로서 cytochrome C의 방출을 유도하여 apoptosis 기전을 활성화시킨다. 본 연구에서는 3T3-L1 지방전구세포에서 CtsD 발현 조절에 관여하는 microRNA에 대해 조사하였다. 먼저 지방전구세포 사멸시 CtsD 발현 변화를 관찰하기 위하여 DNA damage agent인 doxorubicin을 3T3-L1 세포주에 노출시켜 CtsD 발현이 증가함을 확인하였다. 또한 지방전구세포주에서 CtsD가 과발현되면 세포 생존율이 감소하였다. miRanda program을 이용하여 CtsD 유전자를 표적으로 하는 microRNA를 탐색하여 miR-145를 선발하였다. Luciferase reporter assay에 의해 miR-145가 CtsD 유전자의 3' UTR 부위에 결합하여 luciferase 활성을 감소시킴을 관찰하였다. 3T3-L1 세포주에 miR-145 mimic을 도입한 결과 CtsD mRNA 발현과 단백질 수준이 감소하였다. 또한 세포주에 doxorubicin을 처리한 결과 CtsD 유전자 발현 증가와 상반되게 miR-145 발현이 감소하였다. 이외에도 miR-145 inhibitor을 세포에 도입하면 세포 생존율이 감소하였다. 이러한 결과는 지방전구세포의 세포사멸에 CtsD가 관여할 수 있으며, miR-145에 의해 CtsD 발현이 직접 조절되고 있음을 나타낸다. 따라서, 지방전구세포의 사멸을 유도하기 위해서는 miR-145 발현 제어가 주요한 표적이 될 수 있을 것으로 생각된다. 본 연구결과는 향후 비만 예방 및 치료를 위한 지방세포 사멸기전 규명에 중요한 기초 자료를 제공할 수 있을 것으로 기대한다.

• Journal of Microbiology and Biotechnology
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• 제17권12호
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• pp.2056-2060
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• 2007

Transcription factor GATA-3 is the critical transcription factor for Th2 cell differentiation. In spite of its importance in Th2 cell differentiation, the molecular mechanism for its action in Th2 differentiation is poorly understood. Previous studies have suggested that GATA-3 may be involved in the chromatin remodeling in the Th2 cytokine locus. To determine whether GATA-3 exerts its effect on its target sites in the extrachromosomal status, cell transfection assay was performed. In this assay, 800 bp IL4 promoter-luciferase constructs linked with GATA-3 target sites were transfected into the M12 B cell line, D10 mouse Th2 cell lines, and human T lymphoma Jurkat cell lines with or without the GATA-3 expression vector. The GATA-3 effects on its target sites were minimal in the extrachromosomal status, supporting the previous propositions that GATA-3 functions at the chromatin level by remodeling chromatin structure.

• 대한한방부인과학회지
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• 제26권4호
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• pp.140-149
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• 2013

Purpose: The purpose of this study is to investigate the change and correlation of pulse energy in Left and Right Chon, Kwan, Cheok during menstruation, especially around menstruation start date. Methods: The subjects of this experiment were 8 healthy women whose menstruation periods are regular. We measured 3D Blood Pressure Pulse Analyzer (3D-MAC) tests before and after menstruation start date. Results: The results were as follows 1. The pulse energy of the Right Chon was significantly decreased and Left Kwan was comparatively increased during the next day of menstruation start date than previous day. 2. There was a negative correlation between Left Kwan and Left Cheok, Right Chon and Right Kwan pulse energy during the previous and menstruation start date. The negative correlation disappeared between Right Chon and Right Kwan at the next day of menstruation start date. Conclusions: The results suggest that Chon, Kwan, Cheok pulse energy changes are related to menstruation and reflect physiological mechanism of menstruating women. Further study will be needed.

• Advances in Traditional Medicine
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• 제8권3호
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• pp.286-294
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• 2008

We have studied the possible mechanism of anti-asthmatic action of ethanolic extracts of dried seeds of Lepidium sativum (EXLS, 400 mg/kg) using various experimental models. EXLS produced an increase in the Pre-Convulsion Dyspnoea time induced by histamine and acetylcholine aerosol, a significant reduction in the elevated leucocyte counts in the Broncho-Alveolar Lavage fluid of sensitized guinea-pigs and reduction in the paw edema volume as compared to the control rats. Treatment with EXLS also produced decrease in the elevated histamine release from the sensitized guinea-pig lungs. The anti-asthmatic anti-inflammatory responses of EXLS was supported by improvement in microscopic changes like infiltration of inflammatory cells, submucosal edema, epithelial desquamation and reduced lumen size of the bronchi. The $pD_2$ values of histamine in tracheal chain and taenia-coli were significantly greater and that in lung strip was lower in the sensitized animals as compared to control. Treatment of sensitized guinea pigs with EXLS significantly decreased $pD_2$ values of histamine in all three preparations. Our data suggest the prevention of hyper-responsiveness in bronchial smooth muscles and inhibition of the immediate hypersensitive reaction, histamine release in the lungs and the infiltration of various inflammatory cells as the possible mechanisms of anti-asthmatic activity of EXLS.

• Steel and Composite Structures
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• 제22권2호
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• pp.399-409
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• 2016

The fracture propagation mechanism and fractured rock mass failure mechanism were important research in geotechnical engineering field. Many failures and instability in geotechnical engineering were related on fractures propagation, coalescence and interaction in rock mass under the external force. Most of the current research were limited to two-dimensional for the brittleness and transparency of three-dimensional fracture materials couldn't meet the requirements of the experiment. New materials with good transparent and brittleness were developed by authors. The making method of multi fracture specimens were established and made molds that could be reused. The tension-compression ratio of the material reached above 1/6 in normal temperature. Uniaxial and biaxial loading tests of single and double fracture specimens were carried out. Four new fractures were not found in the experiment of two-dimensional fractures such as the fin shaped crack, wrapping wing crack and petal crack and anti-wing crack. The relationship between stress and strain of the specimens were studied. The specimens with the load had experienced four stages of deformation and the process of the fracture propagation was clearly seen in each stage. The expansion characteristics of the fractured specimens were more obvious than the previous research.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.294-298
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• 2003

The complex, unsteady, self-sustained pressure oscillations induced by supersonic flow past a rectangular cavity is investigated using numerical simulations. The present numerical study is performed using a parallel, multiblock solver for the two-dimensional, compressible Navier­Stokes equations. Open cavities with length-to-depth (L / D) ratio in the range 0.5 - 3.3 are considered. This paper sheds light on the cavity physics, cavity oscillatory mechanism, and the organisation of vortical structures inside the cavity. The vortex shedding phenomenon, the shear layer impingement event at the aft wall and the movement of the acoustic/compression wave within the cavity are well predicted. The vortical structures· and the source of the acoustic disturbances are found to be located near the aft wall of the cavity. With the increase in the cavity length, strong recompression of the flow near the aft wall leading to a sudden jump in the cavity form drag is observed. The estimated cavity tones are in good agreement with the available semi­empirical relation. Multiple peaks are noticed in deep and long cavities. For the present free­stream Mach number 1.71, it is observed that around L/D=2.0, the cavity oscillatory mechanism changes from the transverse to longitudinal oscillatory mode. The effects of this transition on various fluid dynamics and acoustic properties are also discussed.

• 한국터널공학회:학술대회논문집
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• 한국터널공학회 2005년도 학술발표회 논문집
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• pp.251-258
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• 2005

In this study, a new concept for simulating a long-term mechanical degradation mechanism of shotcrete in tunnels has been proposed. In fact, it is known that the degradation takes place mainly by internal cracks and reduced stiffness, which results mainly from volume expansion of shotcrete and corrosion of cement materials, respectively. This degradation mechanism of shotcrete in tunnels appears similar to those of the most kinds of chemical reactions in tunnels. Therefore, the mechanical degradation induced by a kinds of chemical reaction was generalized and mathematically formulated in the framework of thermodynamics. The numerical model was implemented to a 3D finite element code, which can be used to simulate behaviour of shotcrete structures undergoing external forces as well as chemical degradation in time. A number of illustrative examples were given to show the feasibility of the model in tunnel designs with consideration of long-term degradation effect of shotcrete quantitatively for increase of long-term safety of tunnels.

• 한국정밀공학회지
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• 제34권1호
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• pp.35-39
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• 2017

We used a construction method using a CNC milling machine, where free-formed molds were made by cutting EPS (Expanded PolyStyrene) foam with the CNC machine, to build free-formed buildings. CNC milling is off-the-shelf technology that can easily cut EPS foam; however its production cost is too high and the time to manufacture an EPS mold is too long. This paper proposes a novel cutting machine with a fast and cost effective mechanism to manufacture EPS concrete molds. Our machine comprises a cutter and Cartesian coordinate type moving mechanism, where the cutter cuts EPS foam using a hotwire in the shape of '$\sqcap$' and is capable of adjusting its cutting angle in real-time while keeping its cutting width. We proved through cutting experiments on the CNC machine that cutting time was greatly shortened compared to the conventional method and that the resulting concrete mold satisfied manufacturing precision.

• Bulletin of the Korean Chemical Society
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• 제19권9호
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• pp.968-973
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• 1998

Solvolyses of para-substituted phenyl chloroformates in water, $D_2O,\;CH_3OD$, 50% $D_2O-CH_3OD$, and in aqueous binary mixtures of acetone, ethanol, methanol are investigated at 25.0 ℃. Product selectivities are reported for a wide range of ethanol-water and methanol-water solvent compositions. These data are interpreted using the Grunwald-Winstein relationship, Hammett equation, and quantum mechanical model. Grunwald-Winstein plots of the first-order rate constants for phenyl chloroformates with $Y_{Cl}$ (based on 1-adamantyl chloride) show marked dispersions into three separate curves for the three aqueous mixtures with a small m value and a rate maximum for aqueous alcohol solvents. To account for these results, third-order rate constants, $k_{ww},\;k_{aw},\;k_{wa}$, and $k_{aa}$ were calculated from the observed $k_{ww}\;and\;k_{aa}$ values together with $k_{aw}\;and\;k_{wa}$ calculated from the computer fit. The kinetic solvent isotope effects determined in water and methanol are consistent with the proposed mechanism of the general base catalyzed carbonyl addition-elimination for para-substituted phenyl chloroformates solvolyses based on mass law and stoichiometric salvation effect studies. This study has shown that the quantum mechanical model predicts transition state variation correctly for $S_N2\;like\;S_AN$ reaction mechanism of para-substituted phenyl chloroformates.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.691-706
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• 2021

This paper aims to numerically investigate violent sloshing in a partially filled three-dimensional (3D) prismatic tank with or without a baffle, further to clarify the suppressing performance of the baffle and the damping mechanism of sloshing. The numerical model is based on a Cartesian grid multiphase flow method, and it is well validated by nonlinear sloshing in a 3D rectangular tank with a vertical baffle. Then, sloshing in an unbaffled and baffled prismatic tank is parametrically studied. The effects of chamfered walls on the resonance frequency and the impact pressure are analyzed. The resonance frequencies for the baffled prismatic tank under different water depths and baffle heights are identified. Moreover, we investigated the effects of the baffle on the impact pressure and the free surface elevation. Further, the free surface elevation, pressure and vortex contours are analyzed to clarify the damping mechanism between the baffle and the fluid.