3,686 research outputs found
Secure MMU: Architectural Support for Memory Isolation among Virtual Machines
No full textIn conventional virtualized systems, a hypervisor can access the memory pages of guest virtual machines without any restriction, as the hypervisor has a full control over the address translation mechanism. In this paper, we propose Secure MMU, a hardware-based mechanism to isolate the memory of guest virtual machines from unauthorized accesses even from the hypervisor. The proposed mechanism extends the current nested paging support for virtualization with a small hardware cost. With Secure MMU, the hypervisor can flexibly allocate physical memory pages to virtual machines for resource management, but update nested page tables only through the secure hardware mechanism, which verifies each mapping change. With the hardware-rooted memory isolation among virtual machines, the memory of a virtual machine in cloud computing can be securely protected from a compromised hypervisor or co-tenant virtual machines
KAIST wireless electric vehicles - OLEV
No full textIn order to minimize the greenhouse effect due to the emission of CO2, automobile manufactures have been developing battery-powered plug-in automobiles with re-chargeable Lithium Polymer batteries. However, these pure electric vehicles (EVs) are not welcomed in the market because the Lithium batteries are heavy and still expensive with limited rechargeable cycles. Furthermore, charging time and relatively short driving range obstruct the commercialization of EVs. To solve the problems, KAIST proposed four generations of On-Line Electric Vehicles (OLEVs), a sort of roadway wireless powered EVs. This paper summarizes the progress of the OLEV developments. Four generations of OLEV were demonstrated for different underground electric power rails and pick-ups. The air-gap of the 1st generation OLEV car is 1 cm and the input to output power efficiency is 80 % with 3 kW output power. The ultra slim U-type mono rail applied to the 2nd generation OLEV bus gives 52 kW output power with 72 % efficiency at 17 cm air-gap. The ultra slim W-type dual rail applied to the 3rd generation OLEV sports utility vehicle delivers 15 kW/pick-up power with 71 % efficiency at 17 cm air- gap, which has recently been improved to 83 % at 20 cm air-gap for an OLEV bus, and 74 % efficiency at 12 cm air-gap for an OLEV train, respectively. The 4th generation of OLEV bus is under development, which has very narrow I-type underground power rails and compact high power pick-ups with drastically reduced electro-magnetic field (EMF), lower construction cost, small installation time, and enhanced lateral displacement. Throughout the development of OLEV, it has shown that low cost EV without high reliance on batteries with sufficiently high power capacity, efficiency, and air-gap is possible, which were the major obstacles of the roadway powered EV for practical applications
theta-curve polynomials and finite-type invariants
No full textThe normalized Yamada polynomial, (R) over tilde (A), is a polynomial invariant in variable A for theta-curves. In this work, we show that the coefficients of (R) over tilde (x)(e) which is obtained by replacing A with e(x) = Sigma x(n)/n! are finite-type invariants for theta-curves although the coefficients of original (R) over tilde (A) are not finite-type. A similar result can be obtained in the case of Yokota polynomial for theta-curves
The Impairments of alpha-Synuclein and Mechanistic Target of Rapamycin in Rotenone-Induced SH-SY5Y Cells and Mice Model of Parkinson's Disease
No full textParkinson’s disease (PD) is characterized by selective degeneration of dopaminergic (DAergic) neurons in the substantia nigra pars compacta (SNpc). α-synuclein (α-syn) is known to regulate mitochondrial function and both PINK1 and Parkin have been shown to eliminate damaged mitochondria in PD. Mechanistic target of rapamycin (mTOR) is expressed in several distinct subcellular compartments and mediates the effects of nutrients, growth factors, and stress on cell growth. However, the contributions of these various regulators to DAergic cell death have been demonstrated mainly in culture with serum, which is known to dramatically influence endogenous growth rate and toxin susceptibility through nutrient and growth factor signaling. Therefore, we compared neurotoxicity induced by the mitochondrial inhibitor rotenone (ROT, 5 or 10 μM for 24 h) in SH-SY5Y cells cultured with 10% fetal bovine serum (FBS), 1% FBS, or 1% bovine serum albumin (BSA, serum-free). In addition, C57BL/6J mice were injected with 12 μg ROT into the right striatum, and brains examined by histology and Western blotting 2 weeks later for evidence of DAergic cell death and the underlying signaling mechanisms. ROT dose-dependently reduced SH-SY5Y cell viability in all serum groups without a significant effect of serum concentration. ROT injection also significantly reduced immunoreactivity for the DAergic cell marker tyrosine hydroxylase (TH) in both the mouse striatum and SNpc. Western blotting revealed that ROT inhibited TH and Parkin expression while increasing α-syn and PINK1 expression in both SH-SY5Y cells and injected mice, consistent with disruption of mitochondrial function. Moreover, expression levels of the mTOR signaling pathway components mTORC, AMP-activated protein kinase (AMPK), ULK1, and ATG13 were altered in ROT-induced PD. Further, serum level influenced mTOR signaling in the absence of ROT and the changes in response to ROT. Signs of endoplasmic reticulum (ER) stress and altered expression of tethering proteins mediating mitochondria-associated ER contacts (MAMs) were also altered concomitant with ROT-induced neurodegeneration. Taken together, this study demonstrates that complex mechanism involving mitochondrial dysfunction, altered mTOR nutrient-sensing pathways, ER stress, and disrupted MAM protein dynamics are involved in DAergic neurodegeneration in response to ROT. © Copyright © 2019 Ramalingam, Huh and Lee.1
Thermal conductivity of KH2PO4 crystal near phase transition
No full text학위논문(석사) - 한국과학기술원 : 물리학과, 1989.2, [ [ii], 35 p. ]한국과학기술원 : 물리학과
Characterization of Hardening Behaviors for 4130 Steel, OFHC Copper, and Ti6Al4V Alloy at High Strain Rate and High Temperature
No full textSynthesis of Patternable Electroluminescent materials and Their Lithographic Application
No full text
An elementary set for theta(n)-curve projections
No full textA finite set of nontrivial theta(n)-curves is shown to be minimal among those which produce all projections of nontrivial theta(n)-curves
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