• Natural Product Sciences
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• v.26 no.3
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• pp.200-206
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• 2020

The ability of the total extract from Physalis angulata; three fractions after partitioning with n-hexane, ethyl acetate (TBE), and water; and four withanolides (compounds 1 - 4) to phosphorylate 5'-adenosine monophosphate-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) in HepG2 cells was evaluated. The TBE fraction (50 ㎍/mL) activated p-ACC and p-AMPK expression most strongly. Compounds 1 - 4 (10 μM) upregulated p-ACC expression at different levels. Compound 4 induced the most significant changes in p-AMPK expression, followed by 1 and 2. Sterol regulatory element-binding proteins (SREBPs) play a functional role in the transcriptional regulation of the lipogenic pathway, including fatty acid synthase (FAS) and ACC. The effects of compounds 2 and 4 (10 μM) on FAS and SREBP-1c expression under high glucose conditions (30 mM) in HepG2 cells were evaluated further. Both dose-dependently inhibited FAS and SREBP-1c expression as well as lipid accumulation (1 - 10 μM) were compared to high-concentration glucose control, which upregulated FAS and SREBP-1c. These results suggest that compounds 2 and 4 upregulate AMPK, suppress FAS and SREBP-1c, and have potential effects on glucose and lipid metabolism.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.16 no.4
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• pp.54-62
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• 2008

International organizations related to air transport such as ICAO, IATA, ACI are forecasting that the number of passenger will grow about 4.4% annually up to 2015. Therefore, the innovation of given system technology and operation procedure is required in global scale to cope with the increase of air traffic demand. CNS/ATM infrastructure based on satellite is considered to play key role in order to solve the problems due to the dramatic increase of air traffic demand over the world. Free flight concept in the air transport operation has been proved with CNS/ATM infrastructure especially in USA and Europe. Therefore, it is necessary to develop key technologies to overcome technology gap and to secure international competitiveness in Korea. ADS-B is an important issue, and new element technologies should be considered as essential items which were shown in Capstone project. Nowadays, the free flight concept is combined to Air Transport Road Map such as NextGen project in USA, SESAR in Europe. In this process, free flight is included in the concepts such as ATM(Air Traffic Management), aviation security and safety, environmental protection and economy development, wide area weather variable reduction service, information integration and application between the related authorities (civil/military) etc. The purpose of research is to establish mid-term and long-term infrastructure plan and strategy for free flight realization in Korea. The analysis of action target and equipment construction status, phase construction plan of infrastructure has been performed by considering mid-term and long-term free flight plans of USA and Europe.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.2
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• pp.29-35
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• 2010

In addition to the Young's modulus, the Poisson's ratio is also at the center of attention in the field stochastic finite element analysis since the parameters play an important role in determining structural behavior. Accordingly, the sole effect of this parameter on the response variability is of importance from the perspective of estimation of uncertain response. To this end, a formulation to determine the response variability in laminate composite plates due to the spatial randomness of Poisson's ratio is suggested. The independent contributions of random Poisson's ratiocan be captured in terms of sub-matrices which include the effect of the random parameter in the same order, which can be attained by using the Taylor's series expansion about the mean of the parameter. In order to validate the adequacy of the proposed formulation, several example analyses are performed, and then the results are compared with Monte Carlo simulation (MCS). A good agreement between the suggested scheme and MCS is observed showing the adequacy of the scheme.

• Structural Engineering and Mechanics
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• v.75 no.4
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• pp.477-485
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• 2020

Finite element (FE) model based structural damage detection (SDD) methods play vital roles in effectively locating and quantifying structural damages. Among these methods, structural model updating should be conducted before SDD to obtain benchmark models of real structures. However, the characteristics of updating parameters are not reasonably considered in existing studies. Inspired by the l_∞ norm regularization, a novel anti-sparse representation method is proposed for structural model updating in this study. Based on sensitivity analysis, both frequencies and mode shapes are used to define an objective function at first. Then, by adding l_∞ norm penalty, an optimization problem is established for structural model updating. As a result, the optimization problem can be solved by the fast iterative shrinkage thresholding algorithm (FISTA). Moreover, comparative studies with classical regularization strategy, i.e. the l₂ norm regularization method, are conducted as well. To intuitively illustrate the effectiveness of the proposed method, a 2-DOF spring-mass model is taken as an example in numerical simulations. The updating results show that the proposed method has a good robustness to measurement noises. Finally, to further verify the applicability of the proposed method, a six-storey aluminum alloy frame is designed and fabricated in laboratory. The added mass on each storey is taken as updating parameter. The updating results provide a good agreement with the true values, which indicates that the proposed method can effectively update the model parameters with a high accuracy.

• Wind and Structures
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• v.24 no.5
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• pp.405-430
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• 2017

The aerodynamic characteristics of vehicles are critical to assess vehicle safety and passenger comfort for vehicles running on long span bridges in a windy environment. However, in previous wind-vehicle-bridge (WVB) system analysis, the aerodynamic interference between the vehicle and the bridge was seldom considered, which will result in changing aerodynamic coefficients. In this study, the aerodynamic coefficients of a high-sided truck on the ground (ground case) and a typical bridge deck (bridge deck case) are determined in a wind tunnel. The effects of existent structures including the bridge deck and bridge accessories on the high-sided vehicle's aerodynamic characteristics are investigated. A three-dimensional analytical framework of a fully coupled WVB system is then established based on the finite element method. By inputting the aerodynamic coefficients of both cases into the WVB system separately, the vehicle safety and passenger comfort are assessed, and the critical accidental wind speed for the truck on the bridge in a windy environment is derived. The differences in the bridge response between the windward case and the leeward case are also compared. The results show that the bridge deck and the accessories play a positive role in ensuring vehicle safety and improving passenger comfort, and the influence of aerodynamic interference on the response of the bridge is weak.

• The Journal of the Acoustical Society of Korea
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• v.34 no.3
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• pp.200-209
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• 2015

An underwater sound surveillance system detects and tracks enemy ships in real-time using hydrophone arrays, in which seabed-mounted sensor arrays play a pivotal role. In this paper the conceptual design of seabed-mounted, cylindrical hydrophone arrays for use in shallow coastal waters is performed via finite element calculations. To stabilize the receiving characteristics under the ocean ambient noise, a technique for whitening the ambient noise spectrum using a metal baffle is proposed. Optimization of the array configuration is performed to achieve the directivity in the vertical and azimuthal directions. And the effects of the sonar dome shape and material on the structural vibration and sound scattering properties are studied. It is demonstrated that a robust hydrophone array, having a sensitivity deviation less than 4 dB over the frequency range of interest, can be obtained through the whitening of the ambient noise, the optimization of the array configuration, and the design of acoustically transparent sonar domes.

• Environmental Analysis Health and Toxicology
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• v.19 no.2
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• pp.191-200
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• 2004

Zinc (Zn) is an essential element in biological process, however inadequate Zn status in general population have been recognized. To update the knowledge for Zn-cadmium (Cd) interaction, we studied the intestinal uptake and transport, and the expression of metal transporter proteins (divalent metal transporter 1, DMT1 ; metal transporter protein 1, MTP1 ; zinc transporter 1, ZnTl ; metallothionein 1 , MT1) in duodenum after Cd exposure using Zn deficient animal model. Rats were led Zn deficient (ZnD, 0.5-1.0 mgZn/kg) or Zn supplemented (ZnS, 50mg Zn/kg) diet for 4 weeks, and followed single administration of $^{109}$ CdCl$_2$orally. The body Zn flatus and tissue Cd concentration were determined at 24 hrs after Cd administration. Total body burden of Cd and Cd absorption index (AI, %) were estimated based on the tissue Cd analyzed. DMT1, MTP1, ZnTl and MT1 mRNA were analyzed by using RT-PCR method. Feeding of Zn deficient diet for 4 weeks produced a reduced body weight gain and a depletion of body Zn. Tissue Cd concentration, body burden of Cd and Cd absorption index were higher in the ZnD diet fed rats than the ZnS diet red rats. Especially, Cd concentration in the small intestine (duodenum, jejunum and ileum) and the colon of FeD diet fed rats were higher markedly than in the FeS diet group. The expression levels of DMT1, MTP1 and ZnT1 mRNA in FeD diet fed rats were similar to the FeS diet. The level of MT1 mRNA expression was significantly lower in the FeD than the FeS diet fed rats. Taken together, theses results indicate that Zn deficiency in diet induce an increased intestinal absorption and tissue retention of Cd, and down -regulate the MT1 expression in the intestine which might be play a part of role in Cd absorption and transport in mammalian. These findings suggest that deficiency of essential metal could be enhanced the toxicity of toxic, non-esstial metals through the metal-metal interaction.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.5
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• pp.333-337
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• 2012

Gene expression of neuronal nitric oxide synthase (nNOS) changes in the hypothalamic paraventricular nucleus (PVN) depending on feeding conditions, which is decreased during food deprivation and restored by refeeding, and phosphorylated cAMP response element binding protein (pCREB) was suggested to play a role in its regulation. This study was conducted to examine if the fasting-induced down-regulation of the PVN-nNOS expression is restored by activation of cAMP-dependent protein kinase A (cAMP/PKA) pathway. Freely moving rats received intracerebroventricular (icv) injection of cAMP/PKA activator Sp-cAMP (40 nmol) or vehicle (sterilized saline) following 48 h of food deprivation. One hour after drug injections, rats were transcardially perfused with 4% paraformaldehyde, and the PVN tissues were processed for nNOS or pCREB immunohistochemistry. Sp-cAMP significantly increased not only nNOS but also pCREB immunoreactivities in the PVN of food deprived rats. Fastinginduced down-regulation of the PVN-nNOS was restored by 1 h after the icv Sp-cAMP. Results suggest that cAMP/PKA pathway may mediate the regulation of the PVN-nNOS expression depending on different feeding conditions.

• The Korean Journal of Physiology and Pharmacology
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• v.12 no.4
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• pp.171-176
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• 2008

Heat shock proteins (HSPs) serve as molecular chaperones and play a role in cell protection from damage in response to stress stimuli. The aim of this article is to investigate whether HSP22 affects IL-8 expression in vascular smooth muscle cells (VSMCs), and which cellular factors are involved in the HSP-mediated IL-8 induction in that cell type in terms of mitogen activated protein kinase (MAPK) and transcription element. Exposure of aortic smooth muscle cells (AoSMCs) to HSP22 not only enhanced IL-8 release but also induced IL-8 transcript via promoter activation. HSP22 activated ERK and p38 MAPK in AoSMCs. HSP22-induced IL-8 release was inhibited by U0126, but not by SB202190. A mutation in the IL-8 promoter region at the binding site of NF-${\kappa}$ B, but not AP-1 or C/EBP, impaired promoter activation in response to HSP22. Delivery of I ${\kappa}$ B, but not dominant negative c-Jun, lowered HSP22-induced IL-8 release from AoSMCs. These results suggest that HS P22 induces IL-8 in VSMCs via ERK1/2, and that transcription factor NF-kB may be required for the HSP22-induced IL-8 up-regulation.

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.196-202
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• 2008

Effective climate protection is a most important tasks of our time. The BIPV is one of the most interesting and promisingly possibilities of an active use of solar energy at the building. In this study it was analyzed by the case study the function of the requirement of the BIPV-module as building material and this architectural characteristic according to the kind of the module. Therefore the goal of this study is to get securing the application information of BIPV as windowpane. BIPV modules are manufactured in the form of G/G. In the case of the crystal type the Transparent and the light Transmission is to be adjusted by the spacer attitude of the cell. Although this type could not be optimal for light effect of indoors because of the inequality of shade, the moving shade play makes a dramatic Roomimage by the run of sun. The application of this type would be for canopy, window or roof in the corridor or resounds. With amorphous the type it is to be manufactured simply largely laminar, and thus that will shorten building process. There is a relatively good economy to use and to the window system easily. After the production technology is easy the transparency of the modules to adjust, and the module shows to a high degree constant characteristics of light permeability and transparency. Without mottle of module shade is good the use for the window or roof glazing of office, library, classroom, etc. to adapt. The BIPV modules took generally speaking a function as building material to the daylight use, shading, isolation and also to the sight. That means that BIPV modules have as multifunctional system to sustainable architecture good successes and they are at the same time as Design element for architecture effectively.