• Title/Summary/Keyword: Fault Injection Analysis

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The Software Reliability Evaluation of a Nuclear Controller Software Using a Fault Detection Coverage Based on the Fault Weight (가중치 기반 고장감지 커버리지 방법을 이용한 원전 제어기기 소프트웨어 신뢰도 평가)

  • Lee, Young-Jun;Lee, Jang-Soo;Kim, Young-Kuk
    • KIPS Transactions on Computer and Communication Systems
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    • v.5 no.9
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    • pp.275-284
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    • 2016
  • The software used in the nuclear safety field has been ensured through the development, validation, safety analysis, and quality assurance activities throughout the entire process life cycle from the planning phase to the installation phase. However, this evaluation through the development and validation process needs a lot of time and money, and there are limitations to ensure that the quality is improved enough. Therefore, the effort to calculate the reliability of the software continues for a quantitative evaluation instead of a qualitative evaluation. In this paper, we propose a reliability evaluation method for the software to be used for a specific operation of the digital controller in a nuclear power plant. After injecting weighted faults in the internal space of a developed controller and calculating the ability to detect the injected faults using diagnostic software, we can evaluate the software reliability of a digital controller in a nuclear power plant.

Pseudotachylyte Developed in Granitic Gneiss around the Bulil Waterfall in the Jirisan, SE Korea: Its Occurrence and Characteristics (지리산 불일폭포 일원의 화강암질편마암에 발달한 슈도타킬라이트: 산상과 특성)

  • Kang, Hee-Cheol;Kim, Chang-Min;Han, Raehee;Ryoo, Chung-Ryul;Son, Moon;Lee, Sang-Won
    • The Journal of the Petrological Society of Korea
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    • v.28 no.3
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    • pp.157-169
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    • 2019
  • Pseudotachylytes, produced by frictional heating during seismic slip, provide information that is critical to understanding the physics of earthquakes. We report the results of occurrence, structural characteristics, scanning electron microscopic observation and geochemical analysis of pseudotachylytes, which is presumed to have formed after the Late Cretaceous in outcrops of the Paleoproterozoic granitic gneiss on the Bulil waterfall of the Jirisan area, Yeongnam massif, Korea. Fault rocks, which are the products of brittle deformation under the same shear stress regime in the study area, are classified as pseudotachylyte and foliated cataclasite. The occurrences of pseudotachylyte identified on the basis of thickness and morphology are fault vein-type and injection vein-type pseudotachylyte. A number of fault vein-type pseudotachylytes occur as thin (as thick as 2 cm) layers generated on the fault plane, and are cutting general foliation and sheared foliation developed in granitic gneiss. Smaller injection vein-type pseudotachylytes are found along the fault vein-type pseudotachylytes, and appear in a variety of shapes based on field occurrence and vein geometry. At a first glance fault vein-type seudotachylyte looks like a mafic vein, but it has a chemical composition almost identical to the wall rock of granitic gneiss. Also, it has many subrounded clasts which consist predominantly of quartz, feldspar, biotite and secondary minerals including clay minerals, calcite and glassy materials. Embayed clasts, phenocryst with reaction rim, oxide droplets, amygdules, and flow structures are also observed. All of these evidences indicate the pseudotachylyte formed due to frictional melting of the wall rock minerals during fault slip related to strong seismic faulting events in the shallow depth of low temperature-low pressure. Further studies will be conducted to determine the age and mechanical aspect of the pseudotachylyte formation.

Coupled Hydrological-mechanical Behavior Induced by CO2 Injection into the Saline Aquifer of CO2CRC Otway Project (호주 오트웨이 프로젝트 염수층 내 CO2 주입에 따른 수리-역학적 연계거동 분석)

  • Park, Jung-Wook;Shinn, Young Jae;Rutqvist, Jonny;Cheon, Dae-Sung;Park, Eui-Seob
    • Tunnel and Underground Space
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    • v.26 no.3
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    • pp.166-180
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    • 2016
  • The present study numerically simulated the CO2 injection into the saline aquifer of CO2CRC Otway pilot project and the resulting hydrological-mechanical coupled process in the storage site by TOUGH-FLAC simulator. A three-dimensional numerical model was generated using the stochastic geological model which was established based on well log and core data. It was estimated that the CO2 injection of 30,000t over a period of 200 days increased the pressure near the injection point by 0.5 MPa at the most. The pressure increased rapidly and tended to approach a certain value at an early stage of the injection. The hydrological and mechanical behavior observed from the CO2 flow, effective stress change and stress-strength ratio revealed that the CO2 injection into the saline aquifer under the given condition would not have significant effects on the mechanical safety of the storage site and the hydrological state around the adjacent fault.

A study on the Heat Transfer Performance according to Ground Heat Exchanger Types (지중열교환기의 종류에 따른 열전달 성능에 관한 연구)

  • Hwang, SuckHo;Song, Doosam
    • KIEAE Journal
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    • v.10 no.4
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    • pp.75-80
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    • 2010
  • Generally, ground-source heat pump (GSHP) systems have a higher performance than conventional air-source systems. However, the major fault of GSHP systems is their expensive boring costs. Therefore, it is important issue that to reduce initial cost and ensure stability of system through accurate prediction of the heat extraction and injection rates of the ground heat exchanger. Conventional analysis methods employed by line source theory are used to predict heat transfer rate between ground heat exchanger and soil. Shape of ground heat exchanger was simplified by equivalent diameter model, but these methods do not accurately reflect the heat transfer characteristics according to the heat exchanger geometry. In this study, a numerical model that combines a user subroutine module that calculates circulation water conditions in the ground heat exchanger and FEFLOW program which can simulate heat/moisture transfer in the soil, is developed. Heat transfer performance was evaluated for 3 different types ground heat exchanger(U-tube, Double U-tube, Coaxial).

Flight Safety Improvement on Surion through Circuit Design and Software Reformation of Data Acquisition Unit (수리온 데이터획득/처리장치 동작회로 및 소프트웨어 개선을 통한 비행안전성 향상)

  • Jun, Byung-kyu;Jeong, Sang-gyu;Kim, Young-mok;Chang, In-ki
    • Journal of Advanced Navigation Technology
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    • v.19 no.5
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    • pp.370-378
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    • 2015
  • The data acquisition unit, signal acquiring and processing equipment, processes and provides major data of an aircraft such as engine system, power train system, hydraulic system, etc. However, it had lots of failure related to the system during production test flight, and it is necessary to fix them perfectly as soon as possible because of the significance of the equipment. In this paper, it contains failure classification and analysis for each defect element to improve whole software as well as electrical circuit. Particularly, utilizing Fault Injection Method based interworking test, more efficient improvement activity was performed for not only equipment level but also aircraft level, and as a result, it is achieved that considerable betterment of Surion quality and flight safety.

A Study on the Risk Analysis and Fail-safe Verification of Autonomous Vehicles Using V2X Based on Intersection Scenarios (교차로 시나리오 기반 V2X를 활용한 자율주행차량의 위험성 분석 및 고장안전성 검증 연구)

  • Baek, Yunseok;Shin, Seong-Geun;Park, Jong-ki;Lee, Hyuck-Kee;Eom, Sung-wook;Cho, Seong-woo;Shin, Jae-kon
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.20 no.6
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    • pp.299-312
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    • 2021
  • Autonomous vehicles using V2X can drive safely information on areas outside the sensor coverage of autonomous vehicles conventional autonomous vehicles. As V2X technology has emerged as a key component of autonomous vehicles, research on V2X security is actively underway research on risk analysis due to failure of V2X communication is insufficient. In this paper, the service scenario and function of autonomous driving system V2X were derived by presenting the intersection scenario of the autonomous vehicle, the malfunction was defined by analyzing the hazard of V2X. he ISO26262 Part3 process was used to analyze the risk of malfunction of autonomous vehicle V2X. In addition, a fault injection scenario was presented to verify the fail-safe of the simulation-based intersection scenario.

Analysis on the Dielectric Characteristics of Various Insulation Gases for Developing a Sub-cooled Liquid Nitrogen Cooling System (과냉질소 냉각시스템 가압용 기체의 절연내력특성 분석)

  • Kang, H.;Ko, T.K.
    • Progress in Superconductivity and Cryogenics
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    • v.13 no.1
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    • pp.27-30
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    • 2011
  • A sub-cooled liquid nitrogen cooling system is known as a most promising method to develop large scale superconducting apparatuses such as superconducting fault current limiters and superconducting cables [1]. Gaseous helium (GHe), gaseous nitrogen ($GN_2$) and sulfur hexafluoride ($SF_6$) are commonly used for designing an high voltage applied superconducting device as an injection gaseous medium [2, 3]. In this paper, the analysis on the dielectric characteristics of GHe, $GN_2$ and $SF_6$ are conducted by designing and manufacturing sphere-to-plane electrode systems. The AC withstand voltage experiments on the various gaseous insulation media are carried out and the results are analyzed by using finite element method (FEM) considering field utilization factors (${\xi}$). It is found that the electric field intensity at sparkover ($E_{MAX}$) of insulation media exponentially decreases according to ${\xi}$ increases. Also, the empirical expressions of the functional relations between $E_{MAX}$ and ${\xi}$ of insulation media are deduced by dielectric experiments and computational analyses. It is expected that the electrical insulation design of applied superconducting devices could be performed by using the deduced empirical formulae without dielectric experiments.

Analysis of Performance Characteristics on Diesel Engine with Aftertreatment and EGR System (후처리 시스템을 장착한 디젤엔진의 EGR 밸브 작동에 따른 성능 분석)

  • Park, Cheol-Woong;Choi, Young;Lim, Gi-Hun
    • Transactions of the Korean Society of Automotive Engineers
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    • v.18 no.5
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    • pp.124-129
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    • 2010
  • The direct injection (DI) diesel engine has become a prime candidate for future transportation needs because of its high thermal efficiency. However, nitrogen oxides (NOx) increase in the local high temperature regions and particulate matter (PM) increases in the diffusion flame region within diesel combustion. Therefore, the demand for developing hybrid system consist of exhaust gas recirculation (EGR) and aftertreatment system as well as diesel particulate filter (DPF) or lean NOx trap (LNT) should be applied. The variation of EGR rate due to the malfunction of EGR valve can affect not only the combustion stability of engine but also the performance of aftertreatment system. In this research, 2.0 liter 4-cylinder turbocharged diesel engine was used to investigate the combustion and emission characteristics for various operating conditions with EGR. While the fuel consumption was increased with increase of EGR rate, NOx emission was improved by maximum 90% at low speed, low load operating condition. To achieve combustion stability and reliability of aftertrearment system with minimum penalty in fuel consumption and emissions, the fault diagnosis of EGR malfunction must be employed.

Insulation Reinforcement of the Electrical Power Cable Degradated by the Water Tree Using Silicon (실리콘을 이용한 수트리 열화된 전력 케이블의 절연 보강)

  • Kang, Hyeong-Gon;Park, Jun-Chae;Ko, Seok-Cheol;Lim, Sung-Hun;Lee, C.H.;Hanh, Y.B.;Han, B.S.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07a
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    • pp.468-471
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    • 2003
  • Fault of under ground power cable occurs usually from the water tree such as the vented tree, the bow tree and the water-rich halo. The water tree penetrates to the polyethylene cable insulations. Sometimes, the water tree also diffuses to mother cable in the substation. In this paper, instead of replacement of the faulty cable, we tried to cure an electrical power cable degraded by the water trees with silicon injection method. And measured the results with the isothermal relaxation current analysis method. After cable cure, Chonil line was improved from 2.27 to 1.96 in a phase, from 2.148 to 2.020 in b phase, and from badness to 2.192 in c phase. And Keumam line was also improved from 2.419 to 1.920 in a phase, from 2.301 to 2.000 in b phase, and from badness to 1.957 in c phase.

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Algorithm of Detecting Ground Fault by Using Insulation Monitoring Device(IMD) in Ungrounded DC System (직류 비접지계통에서 절연저항측정장치(IMD)를 이용한 사고검출 알고리즘)

  • Kim, Ki-Young;Lee, Hu-Dong;Tae, Dong-Hyun;Rho, Dae-Seok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.9
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    • pp.528-535
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    • 2020
  • Recently, the protection coordination method of DC systems has been presented because renewable energy and distributed resources are being installed and operated in distribution systems. On the other hand, it is difficult to detect ground faults because there is no significant difference compared to a steady-state current in ungrounded IT systems, such as DC load networks and urban railways. Therefore, this paper formulates the detection principle of IMD (Insulation Monitoring Device) to use it as a protection coordination device in a DC system. Based on the signal injection method of IMD, which is analyzed by a wavelet transform, this paper presents an algorithm of detecting ground faults in a DC system in a fast and accurate manner. In addition, this paper modeled an IMD and an ungrounded DC system using the PSCAD/EMTDC S/W and performed numerical analysis of a wavelet transform with the Matlab S/W. The simulation results of a ground fault case in an ungrounded DC system showed that the proposed algorithm and modeling are useful and practical tools for detecting a ground fault in a DC system.