CPS에서의 물리 에러를 방지하는 안전 보장 메커니즘

학위논문(석사) -- 서울대학교대학원 : 공과대학 컴퓨터공학부, 2023. 2. 이창건.This paper considers a cyber-physical system with a so-called self-looping node that repeats the inner-loop for physical situation awareness, i.e., more loops for more harsh physical situations. Regarding such a self-looping node, we observe the existence of physical errors that make the looping useless and eventually cause a critical failure. To prevent such a critical failure despite a physical error, this paper proposes a novel mechanism by introducing time wall and safety backup. The time wall limits the time budget for the self-looping node so as to switch to the safety backup while still meeting the deadline to prevent critical failure despite physical errors. Our experiments through both simulation and actual implementation show that the proposed mechanism gives a comparable accuracy with the existing methods in normal cases while completely preventing critical failure in physical error cases.본 논문은 물리 상황 인지를 위해 내부 루프를 반복하는 자기반복 모듈(self-looping module)이 있는 사이버 물리 시스템을 고려한다. 자기반복 모듈은 더 높은 정확도를 위해 내부 루프를 반복하지만, 설계 단계에서 고려되지 못한 물리 환경을 마주하게 되면 루프를 반복하더라도 목표 정확도에 도달하지 못하는 물리 에러(physical error) 상황이 발생할 수 있다. 문제는 현재의 시스템의 경우 자기반복 모듈이 물리 에러를 인지하지 못하기 때문에 계속해서 루프를 반복하게 되고, 데드라인을 놓치는 등 시스템 자체의 치명적인 오류로 이어진다는 것이다. 본 논문에서는 물리 에러 상황에서도 최소한의 안전을 보장하기 위해 시간 장벽(time wall)과 안전 백업(safety backup)을 도입한 새로운 메커니즘을 제안한다. 시간 장벽은 자기반복 모듈의 최대 수행 시간으로, 자기반복 모듈이 시간 장벽만큼 실행했는데도 목표 정확도에 도달하지 못하면 안전 백업 모드로 전환한다. 본 논문은 시뮬레이션과 실제 자율주행 소프트웨어인 Autoware에 제안하는 메커니즘을 적용하여 제안하는 메커니즘이 치명적 오류를 완전히 방지하면서, 실제 자율주행 소프트웨어에도 적용 가능함을 보였다.1 Introduction 1 2 Related Work 5 3 Task and Resource Model 6 4 Safety Guarantee Mechanism Against Physical Errors 9 5 Classic Bound based Budget Analysis 13 5.1 Some Useful Computations on DAGs 14 5.2 Simple Solution 15 5.3 Solution with LP 18 6 CPC based Budget Analysis 21 6.1 Initial Budget Calculation 24 6.2 Binary Search for Finding the Optimal Budget 26 7 Generalize to Multiple Self-looping Nodes 30 7.1 Ambiguity in multiple self-looping nodes 30 7.2 Multiple Self-Looping Nodes: A Formal Model 32 7.3 Multiple self-looping nodes: Computing WCETs 34 8 Evaluation 37 8.1 Simulation with Synthetic DAG Workload 37 8.2 Implementation 42 9 Conclusion 46 9.1 Summary 46 9.2 Future Work 46 References 48석

A Study on the formation of organotypic spheroids from early human fetal brain

학위논문(박사)--서울대학교 대학원 :의학과 신경외과학전공,1995.Docto

Macrolactins produced by an actinomycete isolated from marine samples

Marine actinomycetes represent an unexploited source for the discovery of novel secondary metabolites. The exploitation of marine actinomycetes as a source for novel bioactive metabolites is in its infancy. Even with the limited screening efforts that have been dedicated to date to marine actinomycetes, the discovery rate of novel bioactive metabolites from marine actinomycetes has recently surpassed that of their terrestrial counterparts. As evident by the isolation of many new compounds from marine actinomycetes, there is a tremendous potential for the isolation of novel secondary metabolites from marine actinomycetes. In our search for bioactive metabolites from marine actinomycete, we could isolate a strain which produces macrolactin derivatives. Macrolactin A, a 24-membered lactone, had previously been reported to show antibacterial, cytotoxic and antiviral activities. We identified the marine actinomycete through 16S rRNA sequence analysis and report here the isolation and structure elucidation of macrolactins.1

A cyclic tetrapeptide from the Arctic marine bacterium

Marine organisms are widely recognized as emerging sources of new secondary metabolites with wide range of biological activities compared to terrestrial microorganisms. A marine bacterium strain, designated as 03N67, was isolated from a seaweed sample collected from the Arctic. A cyclic tetrapeptide was isolated from the culture broth of this strain. The structure of this compound was elucidated based on MS, NMR and literature review.1

Two b-carboline compounds from Marine Streptomyces spp.

The oceans are a unique resource that provides a diverse array of natural products as 34 of the 36 phyla of life are represented in the biodiversity of the marine environment. Among them, the marine actinomycetes are recognized as a valuable source of bioactive molecules. In this research, chemical investigation of the Streptomyces sp. has resulted in the isolation of two b-carboline compounds, 1-methyl-b-carboline and 1-acetyl-b-carboline. The structures of these compounds are determined by spectroscopic means.1

Diketopiperazine derivatives from a Tropical Sponge Associated Marine Actinomycete

Marine organisms are a recognized source of novel metabolites with valuable biological properties and molecular diversity. Marine organisms have evolved with unique metabolic and physiological capabilities to adapt themselves to extreme habitats. They produce the potent bioactive compounds that would not be observed from terrestrial microorganisms. From the fact that actinomycetes isolated from marine organism are promising sources for secondary metabolites such as antibiotic substances, we have focused our exploration of the isolation, structural elucidation of bioactive compounds from marine microorganisms. In our ongoing research to develop the biomedical potential of marine actinomycetes, we isolated four compounds of proline based cyclic dipeptides, diketopiperazines (DKPs), previous studies. DKPs have been shown to exhibit antitumor activity, antimicrobial activity, quorum sensing signal, inhibition against aflatoxin production, plant growth promotion and other activities.2

1-Acetyl-ß-carboline compound isolated from a marine actinomycete strain 04DH211

Recently, marine organisms are a recognized source of novel metabolites with valuable biological properties and molecular diversity. Marine organisms have evolved with unique metabolic and physiological capabilities to adapt themselves to extreme habitats. They produce the potent bioactive compounds that would not be observed from terrestrial microorganisms. From the fact that actinomycetes isolated from marine organisms are promising sources for secondary metabolites such as antibiotic substances. Thus, we have focused our exploration on the isolation, structural elucidation of bioactive compounds from marine microorganisms. In the course of our continuing search for new anticancer materials from marine derived actinomycetes, eudistomin class compound was isolated from the culture broth of strain 04DH211. The structure of this compound, which possess significant antibiotic properties, cancer cell cytotoxicities, antifungal, antibacterial in vitro bioassays, was assigned by spectral measurements and comparison with extensive MS, UV and NMR spectral analyses. In this paper we describe the isolation, structure elucidation of this compound.1

Diketopiperazines from the Culture Broth of a Marine Actinomycete Promicromonospora sp.

Diketopeperazines (DKPs) and their derivatives are widely distributed in nature as secondary metabolites. They have a wide variety of biological activities including antitumor, antiviral, antifungal and antibacterial activities.As marine environmental conditions are extremely different from terrestrial ones, it is surmised that marine actinomycetes have different characteristics from those of terrestrial counterparts and, therefore, might produce different types of bioactive compounds. In our on-going research to develop the biomedical potential of marine actinomycetes, we isolated several diketopiperazines from the fermentation broth of a marine actinomycete, Promicromonospora sp. strain. The structures of these diketopiperazines were determined using spectroscopic methods. The fermentation, isolation, and structure elucidation of diketopiperazines will be presented.2

An Angiogenesis Inhibitor from Marine-Derived Actinomycete, Nocadiopsis sp.

An angiogenesis inhibitor was isolated from the culture broth of Nocariopsis sp. which was obtained from a seaseed samploe collected from Arctic. This compound showed anti-angiogenesis activity against human umbilical vein endothellial cells (HUVECs). The structure of this compound was determined by MS, 1D and 2D NMR spectral data analysis. The relative stereochemistry of this compound was determined by Marfesy's method.2

(A) study on the development of marine biological resources in the southwest pacific (A coordinated report of marine biological resources study from 2000 to 2007)

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