Affordable techniques for dependable microprocessor design

As high computing power is available at an affordable cost, we rely on microprocessor-based systems for much greater variety of applications. This dependence indicates that a processor failure could have more diverse impacts on our daily lives. Therefore, dependability is becoming an increasingly important quality measure of microprocessors.;Temporary hardware malfunctions caused by unstable environmental conditions can lead the processor to an incorrect state. This is referred to as a transient error or soft error. Studies have shown that soft errors are the major source of system failures. This dissertation characterizes the soft error behavior on microprocessors and presents new microarchitectural approaches that can realize high dependability with low overhead.;Our fault injection studies using RISC processors have demonstrated that different functional blocks of the processor have distinct susceptibilities to soft errors. The error susceptibility information must be reflected in devising fault tolerance schemes for cost-sensitive applications. Considering the common use of on-chip caches in modern processors, we investigated area-efficient protection schemes for memory arrays. The idea of caching redundant information was exploited to optimize resource utilization for increased dependability. We also developed a mechanism to verify the integrity of data transfer from lower level memories to the primary caches. The results of this study show that by exploiting bus idle cycles and the information redundancy, an almost complete check for the initial memory data transfer is possible without incurring a performance penalty.;For protecting the processor\u27s control logic, which usually remains unprotected, we propose a low-cost reliability enhancement strategy. We classified control logic signals into static and dynamic control depending on their changeability, and applied various techniques including commit-time checking, signature caching, component-level duplication, and control flow monitoring. Our schemes can achieve more than 99% coverage with a very small hardware addition. Finally, a virtual duplex architecture for superscalar processors is presented. In this system-level approach, the processor pipeline is backed up by a partially replicated pipeline. The replication-based checker minimizes the design and verification overheads. For a large-scale superscalar processor, the proposed architecture can bring 61.4% reduction in die area while sustaining the maximum performance

Applicability of Diffuse Ultrasound to Evaluation of the Water Permeability and Chloride Ion Penetrability of Cracked Concrete

This study aims to explore the applicability of diffuse ultrasound to the evaluation of water permeability and chloride ion penetrability of cracked concrete. Lab-scale experiments were conducted on disk-shaped concrete specimens, each having a different width of a penetrating crack that was generated by splitting tension along the centerline. The average crack width of each specimen was determined using an image binarization technique. The diffuse ultrasound test employed signals in the frequency range of 200 to 440 kHz. The water flow rate was measured using a constant water-head permeability method, and the chloride diffusion coefficient was determined using a modified steady-state migration method. Then, the effects of crack width on the diffusion characteristics of ultrasound (i.e., diffusivity, dissipation), water flow rate, and chloride diffusion coefficient are investigated. The correlations between the water flow rate and diffuse ultrasound parameters, and between the chloride diffusion coefficient and diffuse ultrasound parameters, are examined. The results suggest that diffuse ultrasound is a promising method for assessing the water permeability and chloride ion penetrability of cracked concrete

The effect of various design codes and dynamic magnification on buildings with torsional irregularity

Seismic provisions have utilized design eccentricities to reduce planar irregularities in lateral stiffness of buildings. In calculating a design eccentricity, the torsional amplification factor may be applied either to accidental eccentricity or to both inherent and accidental eccentricities according to design codes. In this paper, different code provisions and their impact on torsional responses of buildings are investigated using example buildings with various aspect ratios and inherent eccentricities. It was found that the design eccentricity in KBC-2009 using torsional amplification factor for only accidental eccentricity reflects the dynamic magnification more accurately than that in KBC-2006 using this factor for both inherent and accidental eccentricity. And dynamic magnification of a torsionally imbalanced building is affected by the size of seismic design force of response spectrum analysis than design eccentricity of equivalent static analysis in KBC-2009. In other words, design eccentricity including torsional amplification factor in KBC-2009 do not reflect the dynamic magnification accurately

Pore engineering of metal-organic frameworks with coordinating functionalities

Among porous materials, metal-organic frameworks (MOFs) take the lead in heterogeneous support catalysts because the structure of MOFs can be readily tuned by choice of metal and organic building blocks, and further be modified with diverse functional groups. In order to immobilize catalytically active metal sites on MOFs and efficiently utilize them, it would be essential to employ the coordinating functionalities to the pores and frameworks, which can anchor the metal sites with high stability and control the reactivity of the catalytic centres. However, in order not to obtain the unwanted structures by participation of additional coordinating groups in the framework construction of MOFs, the pore engineering with coordinating functionalities should be carefully implemented. In this review, we discuss various strategies of pore engineering to impart catalytic activities to the MOF architectures, classifying them into two approaches: pre-integrated ligand and sequential attachment. The former demonstrates the use of organic ligands that are already capable of possessing catalytic sites, and the ligands can directly integrate the metals before or after the production of the MOFs. The other approach is the post-synthetic attachment of coordinating functionalities through the sequential attachment process, in which immobilization of catalytically active metal sites also can be achieved by both pre- and post-metalation. Finally, this review will comprehensively discuss the representative catalytic reactions of MOF-based heterogeneous catalysts. (C) 2020 Elsevier B.V. All rights reserved

Rhus verniciflua Stokes against Advanced Cancer: A Perspective from the Korean Integrative Cancer Center

Active anticancer molecules have been searched from natural products; many drugs were developed from either natural products or their derivatives following the conventional pharmaceutical paradigm of drug discovery. However, the advances in the knowledge of cancer biology have led to personalized medicine using molecular-targeted agents which create new paradigm. Clinical benefit is dependent on individual biomarker and overall survival is prolonged through cytostatic rather than cytotoxic effects to cancer cell. Therefore, a different approach is needed from the single lead compound screening model based on cytotoxicity. In our experience, the Rhus verniciflua stoke (RVS) extract traditionally used for cancer treatment is beneficial to some advanced cancer patients though it is herbal extract not single compound, and low cytotoxic in vitro. The standardized RVS extract's action mechanisms as well as clinical outcomes are reviewed here. We hope that these preliminary results would stimulate different investigation in natural products from conventional chemicals

Recent progress of coherent beam combining Kumgang Laser (0.4J@10kHz/10ns)

A coherent beam combining is the most promising technique to achieve a high output energy and a high repetition rate laser system with a good beam quality [1]. It has been demonstrated experimentally that the coherent beam combination using self-phase-controlled stimulated Brillouin scattering phase conjugate mirror (SC-SBS-PCM) is the simplest coherent beam combination method [2-3]. For an average output power of a kW range, the experimental verification of coherent beam combination is now underway by the Kumgang laser [4-5]..

Recent progress of coherent beam combining Kumgang Laser (0.4J@10kHz/10ns)

A coherent beam combining is the most promising technique to achieve a high output energy and a high repetition rate laser system with a good beam quality [1]. It has been demonstrated experimentally that the coherent beam combination using self-phase-controlled stimulated Brillouin scattering phase conjugate mirror (SC-SBS-PCM) is the simplest coherent beam combination method [2-3]. For an average output power of a kW range, the experimental verification of coherent beam combination is now underway by the Kumgang laser [4-5]..

Switchable tribology of ferroelectrics

Artificially induced asymmetric tribological properties of ferroelectrics offer an alternative route to visualize and control ferroelectric domains. Here, we observe the switchable friction and wear behavior of ferroelectrics using a nanoscale scanning probe where down domains having lower friction coefficient than up domains can be used as smart masks as they show slower wear rate than up domains. This asymmetry is enabled by flexoelectrically coupled polarization in the up and down domains under a sufficiently high contact force. Moreover, we determine that this polarization-sensitive tribological asymmetry is universal across ferroelectrics with different chemical composition and crystalline symmetry. Finally, using this switchable tribology and multi-pass patterning with a domain-based dynamic smart mask, we demonstrate three-dimensional nanostructuring exploiting the asymmetric wear rates of up and down domains, which can, furthermore, be scaled up to technologically relevant (mm-cm) size. These findings establish that ferroelectrics are electrically tunable tribological materials at the nanoscale for versatile applications.Peer ReviewedPostprint (author's final draft