• Title/Summary/Keyword: 손상코드

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Modeling of Damage Caused to Injectors Used in Pulverized-Coal-Oxygen-Combustion Furnace (순산소와 미분탄 가스 연소에 의한 용융로 풍구 선단부 손상 모델링: 폭굉 압력파에 의한 영향)

  • Gwak, Min-Cheol;Kwon, Ki-Woong;Lee, Sang-Ho;Yoh, Jai-Ick
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.11
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    • pp.957-964
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    • 2010
  • The deflagration-to-detonation transition (DDT) causes a strong pressure wave that can adversely affect surrounding structures. The pressure generated by multiple detonative pulses is strong enough to cause metal surface erosion and chipping of the edges of bulk structures. In this study, we investigate the damage caused by the DDT phenomenon and perform hydrocode simulations to evaluate the structural damage caused to a metallic pulverized-coal injector used in a pulverized-coal-oxygen combustion furnace. The experimental conditions are selected in order to accurately model the damage caused to metal injectors that are exposed to multiple DDT pulses.

Sensitivity analysis of tunnel stability with a consideration of an excavation damaged zone (암반손상대를 고려한 터널 안정성 민감도 분석)

  • Kim, Jin-Soo;Kwon, Sanki
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.16 no.1
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    • pp.91-104
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    • 2014
  • An Excavation Damaged Zone (EDZ), in which rock properties are permanently changed due to blasting impact or stress redistribution, can influence the behavior and stability of structures. In this study, the mechanical stability of an underground opening was simulated by using FLAC, which is a two-dimensional modeling code, with a consideration of EDZ. A sensitivity analysis was also carried out with fractional factorial design. From the modeling, it was found that the behavior and the stability of an underground tunnel are strongly dependent on the existence of the EDZ. The sensitivity analysis showed that the key parameters affecting the factor of safety around the tunnel are in-situ stress ratio, depth, cohesion, reduction ratio, internal friction angle, and height and width of the tunnel. It is necessary to consider the EDZ, which can significantly affect mechanical stability in tunnel design.

Calculation of Probabilistic Damage Stability Based on Grid Model (격자모델을 이용한 확률론적 손상복원력 계산의 전산화)

  • Jong-Ho Nam;Won-Don Kim;Kwang-Wook Kim
    • Journal of the Society of Naval Architects of Korea
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    • v.31 no.1
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    • pp.14-21
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    • 1994
  • The studios on the stability of damaged ships have been carried out continuously to prevent frequent damages or sinkings which cause large loss of life and fortunes. For dry cargo ships, continuing losses have resulted in new legislation of the probabilistic damage stability. IMO has developed requirements for the subdivison and damage stability of dry cargo ships based on probabilistic concepts. The calculation of the probabilistc damage stability is a complicated and iterative job hence development of computer programs is indispensable. In this research, programming of the probabilistic damage stability according to new requirements has been done and the results were compared with those carried out by the other foreign packages. New algorithm using a grid model in a transversal section was introduced to reduce efforts in preparing input data for damage scenarios and as a result, has brought significant improvement in efficiency and performance.

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A Study on the Short-Circuit Characteristics of Vinyl Cords Damaged by External Flame (외부화염에 의해 소손된 비닐 코드의 단락 특성에 관한 연구)

  • Choi Chung-Seog;Kim Hyang-Kon;Shong Kil-Mok
    • Fire Science and Engineering
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    • v.18 no.4
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    • pp.72-77
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    • 2004
  • In this paper, we studied on the short-circuit process, surface structure, and component variation of vinyl cords. In the results of high speed imaging system (HSIS) analysis, as soon as wire covering was damaged by heat, the conductor of wire came in contact with the other conduct of wire, and the short-circuit occurred. Stereomicroscope and SEM analysis indicated that the source part of wire showed V-type form. The molten beads of load part were bigger than those of source part. In the results of EDX analysis, Cu and O were detected in the source part, whereas covering material (Cl, Ca), Cu and O were detected in the load part. The results will help us to find out the cause of electrical fire.

Investigation on the Change of Ammonia Dissociation for Satellite Thruster According to the Catalyst Loss (위성추력기에서 촉매유실에 따른 암모니아 해리도 변화에 대한 연구)

  • Hwang, Chang-Hwan;Lee, Sung-Nam;Baek, Seung-Wook;Kim, Su-Kyum;Yu, Myoung-Jong
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.11a
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    • pp.218-222
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    • 2011
  • During the development of the iridium catalyst for domestic production, the catalyst failure, loss, sintering phenomena are observed by high pressure and temperature. By these abnormal failure of catalyst bed, the performance of thruster is degraded. To figure out the detail phenomena on the damaged catalyst bed, a numerical analysis code is developed by assuming the catalyst bed as an one dimensional porous media. The numerical analysis code is validated with experiment data. Thereby, resulting physical phenomena are examined by considering the variation of catalyst bed characteristics incurred by catalyst granule failure. Through these numerical analyses we figure out the effect of the catalyst loss on the decomposition of hydrazine and ammonia.

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An analysis of Content Disarm and Reconstruction (콘텐츠 무해화 및 재조합 기술 연구 분석 및 고찰)

  • Sohyeon Oh;Abir EL Azzaoui;Jong Hyuk Park
    • Annual Conference of KIPS
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    • 2023.05a
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    • pp.206-208
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    • 2023
  • 비대면 활동 및 원격 작업 증가에 따라 문서 파일을 이용한 사이버 공격 빈도가 증가하고 있으며, 별도의 실행 파일 대신 문서 내의 기본적인 기능을 악용하는 문서 공격은 기존의 악성코드 탐지 메커니즘을 우회할 수 있기 때문에 큰 문제가 되고 있다. 이러한 문제에 대응하기 위한 여러 기술 중 CDR 기술은 악성 행위에 이용될 가능성이 있는 액티브 콘텐츠를 제거하거나 비활성화하여 사전에 악성코드로 탐지되지 않았던 파일에 대한 보안성을 제공하지만, 문서의 내용을 분석하고 안전하게 재조합하는 과정에서 오류가 발생하여 전달하고자 했던 내용을 제대로 표현할 수 없게 되거나, 파일을 사용할 수 없게 되는 문제가 발생할 수 있다. 본 논문에서는 파일을 후처리하는 방식으로만 CDR을 적용하는 것이 아니라, 확장 프로그램이나 가상 환경 등을 이용해 문서의 작성 단계에서부터 CDR 처리과정을 거치게 하는 방법을 제안하여 파일 손상이나 내용 누락 문제를 완화하고 사용자의 업무 효율을 높이는 동시에 강화된 보안성을 제공한다.

Factors Influencing Treatment Result in Inpatients with Tuberculosis (결핵입원환자의 치료결과에 영향을 미치는 요인)

  • Lee, Hyun-Sook;Hwang, Seul-Ki;Kim, Sang-Mi
    • The Journal of the Korea Contents Association
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    • v.16 no.10
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    • pp.196-205
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    • 2016
  • The purpose of this study is to identify factors influencing treatment result in patients with Tuberculosis by patient characteristic, admission and disease characteristic, and hospital characteristic from 2006 to 2012. Survey data was using Korean national hospital discharge in-depth survey data produced by KCDC(Korea Center for Disease Control and Prevention). Study subjects were 8,305 inpatients with TB(A15.0~A19.9) and analyzed frequency, chi-square test, and logistic regression by using SPSS 20(Statistical Package for the Science). The results of this study show that influencing factors of treatment result were ages (20-39, 40-64, and over 65 years), type of insurance(medical aid), disease code (A16, A17, A18, A19), LOS (31-90, and 91-180 days), beds of hospital (300-499, 500-999, over 1,000 beds) and hospital district (non-metropolitan). These findings implied that it is necessary to support successful prevention and management for high risk TB groups and to build middle and long-term policies as well as short -term policy.

A Design of Security Structure in Bare Metal Hypervisor for Virtualized Internal Enviroment of Cloud Service (클라우드 서비스 가상화 내부 환경을 위한 BareMetal Hypervisor 기반 보안 구조 설계)

  • Choi, Do-Hyeon;You, Han-Na;Park, Tae-Seung;Do, Kyoung-Hwa;Jun, Moon-Seog
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38B no.7
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    • pp.526-534
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    • 2013
  • With rapid rise of virtualization technology from diverse types of cloud computing service, security problems such as data safety and reliability are the issues at stake. Since damage in virtualization layer of cloud service can cause damage on all host (user) tasks, Hypervisor that provides an environment for multiple virtual operating systems can be a target of attackers. This paper propose a security structure for protecting Hypervisor from hacking and malware infection.

Design Enhancements of Automatic Depressurization System in a Passive PWR (피동형 경수로 자동감압계통의 개선에 관한 연구)

  • Yu, Sung-Sik;Seong, Poong-Hyun
    • Nuclear Engineering and Technology
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    • v.25 no.4
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    • pp.515-528
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    • 1993
  • In a Passive PWR, the successful actuation of Automatic Depressurization System (ADS) is essentially required so that no core damage is occurred following small LOCA. But it has been shown in the previous studies that Core Damage Frequency (CDF) from small LOCA is significantly caused by unavailability of ADS. In this study, the design vulnerabilities impacting the ADS unavailability have been identified and the design improvement items have been proposed through the system reliability assessment using the fault tree methodology The impacts on CDF according to the change of system unavailability have also been analyzed. In addition, small LOCA simulation using RELAP5/MOD3 code has been performed to show the thermal-hydraulic feasibility of the suggested design enhancements.

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Nonlinear Explosion Analyses for Damage Assessments of Reinforced Concrete Structures (비선형 폭발해석에 의한 콘크리트 구조물의 손상도 평가)

  • Huh, Taik Nyung;Kim, Seong Yun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.37 no.1
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    • pp.1-7
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    • 2017
  • In general, the large loads which are applied from explosion, impact, earthquake and wind at a short time caused the materials of structures to large deformations, rotations and strains locally. If such phenomena will be analyzed, hydrocodes which can be considered fluid-structure interaction under computational continuum mechanics are inevitably needed. Also, the explosion mechanism is so complicated, it is reasonable that the behaviors of structure are predicted through explosion analyses and experiment at the same time. But, unfortunately, it is true that explosion experiments are limited to huge cost, large experiment facilities and safety problems. Therefore, in this study, it is shown that the results of explosion analyses using the AUTODYN are agreed with those of existing explosion experiments for reinforced concrete slabs within reasonable error limits. And the explosion damage of the same reinforced concrete slab are assessed for quite different reinforcement arrangement spacings, concrete cover depths, and vertical reinforcements. From the explosion analyses, it is known that the more the ratio of slab thickness to reinforcement arrangement spacing is increased, and small-diameter reinforcements are used than large-diameter reinforcements on the same reinforcement ratio, and vertical reinforcements are used, the more the anti-knock capacities are improved.