• Title/Summary/Keyword: Safety of lifes

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A Study of Strain Waveform Effect on Fatigue Life in High Temperature Low Cycle Fatigue Test (고온저사이클 피로시험에서 변형률파형이 피로수명에 미치는 영향에 대한 연구)

  • 유재환
    • Journal of the Korean Society of Safety
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    • v.14 no.1
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    • pp.41-48
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    • 1999
  • The fatigue life tests were performed in strain control with triangular and hole-time wave-forms at $650^{\circ}C$. The fatigue lifes were investigated according to waveform examining damage mechanisms, which could be used to predict the fatigue life and estimate the remaining life. The results obtained are as follows; The fatigue lifes were in order of the fast-fast>the fast-slow>the slow-fast in the triangular waveforms, and the fatigue lifes in slow-fast waveforms got shorter in the hold-time waveforms. The damage mechanisms of the fracture surfaces were transgranular fracture in the fast-fast, the fast-slow waveforms and intergranular fracture in the slow-fast waveform.

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A Study on Walking Speed of the Disabled by Welfare Center Classification (장애인 시설별 장애인 이동속도에 관한 연구)

  • Kim, Eung Sik;Lee, Jeong Su;Kim, Jang Hwan;Kim, Myeoung Hun
    • Journal of the Korean Society of Safety
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    • v.31 no.5
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    • pp.124-132
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    • 2016
  • Welfare centers for disabled person which are typical facilities in Korea are classified into two catagories One is general welfare center for all type of disabled persons and the other is special welfare centers for special disabilities such as visually handicapped persons, hearing-impaired persons and the physically disabled. In this study the movements of disabled persons in daily lifes were measured and many evacuation drills in welfare centers were conducted for the achievement of basic data such as velocities and evacuation patterns of disabled persons The evacuation patterns are characterized by different kinds of disabilities.

Estimating the Value of the North Korean Renewable Energy Power Market Taking into Account North Korea's Power Generation and the Safety of Its Inhabitants (북한 발전과 주민 안전을 고려한 북한 신재생에너지 전력 시장 가치 추정)

  • Jang, Hyung Sik;Koo, Il Seob
    • Journal of the Korea Safety Management & Science
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    • v.24 no.3
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    • pp.75-84
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    • 2022
  • While protecting its lives and property from natural disasters such as floods and droughts, North Korea needs to develop into an informationized industrial society by securing renewable energy power in the era of energy transition. In addition, existing research has considered that a policy of continuous and consistent expansion of renewable energy based on the safety of the lives of ordinary people could be the solution. South Korea needs to recognize that the supply of energy for a minimum of living is more important to the North Korean people than the economic benefits of securing North Korea's renewable energy market. Therefore, in this paper, from that point of view, we have calculated the amount of electricity that North Korea lacks necessary for the lives of its inhabitants that can be replaced by renewable energy, and considered ways to estimate the market value.

A Study on Fatigue Characteristics of Domestic Low-Relaxation PS Strands (국산 저이완 PS 강연선의 피로특성에 관한 연구)

  • 변근주;송하원;박상순;노병철
    • Journal of the Korea Concrete Institute
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    • v.11 no.6
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    • pp.113-119
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    • 1999
  • Fatigue failure is a phenomenon such that structures under cyclic service load is failed by sudden brittle manner. Therefore, in order to obtain structures safety against the fatigue failure during their service lifes, fatigue characteristics should be considered for design and analysis of the structures. As stress range of prestressed (PS) tendons, which governs fatigus characteristic of prestressed concrete (PSC) structures, increases with increased use of partial prestressig, it is more necessary to consider fatigue characteristics of PS tendons. In this paper, direct-tension fatigue experiments with special specimen-setting devices are carried out to obtain fatigue characteristics of domestic low relaxation PS strands having different diameters and PS strands connected with coupler. Then, allowable stress range of fatigue for PSC beams using low relaxation strands are presented for the fatigue examination of prestressed concrete beams applied cyclic loading.

A Study on the Reliability Analysis for Smoke Detector using Dust (분진을 이용한 연기감지기 신뢰성 분석에 관한 연구)

  • Hong, Sung Ho;Choi, Moon Soo;Lee, Young Man
    • Journal of the Korean Society of Safety
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    • v.28 no.6
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    • pp.11-16
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    • 2013
  • This paper presents a study on the analyzing reliability of smoke fire detector using accelerated life test. In general, the smoke fire detector is broken by dust which flow in smoke detection chamber. In order to conduct accelerated life test of smoke fire detector dust is set accelerated factor in this paper. The dust is fly-ash which is test particle 5th regulated by KS A 0090. The dust accelerated level is 60 g, 180 g and 360 g and failure time is measured by smoke sensitivity testing. It is considered to failure of detector if detector don't operate within 30 secconds when subjected to an air stream having a velocity of 20 cm/s~40 cm/s containing smoke with a concentration of 15% of rate of light-response of 1 m. The goodness of fit test and mean life prediction conduct using the failure time. The result show that life distribution fits the weibull distribution for failure time data and the mean lifes calculate 22.5 year in domestic product and 14.7 years in overseas product applied dust stress only.

A Study on the Development of a Training Course for Maritime Security Operatives (해상특수경비원 교육과정 개발에 관한 연구)

  • Doo, Hyun-Wook;Ahn, Young-Joong;Jo, So-Hyun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.24 no.2
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    • pp.223-231
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    • 2018
  • In West Africa and Southeast Asia including Somalia, piracy attacks still take place that threaten safety of ships and the lifes of seafarers. In order to protect Korean flag ships and the seafarers on board from piracy attacks, the government of the Republic of Korea established the Act to Prevent Piracy Attacks on International Ships on Dec. 27, 2016. This act legally provides for the establishment of Maritime Security Operatives (MSO) on board ships navigating high risk areas to ensure security. Furthermore, mandated training for MSOs is required to prepare them to carry out their duties effectively. In this paper, a new training course for MSOs according to domestic law is suggested through analysis of IMO documents and the MSO training provided by foreign nations.

A Study on the Fatigue Life Prediction and Evaluation of Rubber Components for Automobile Vehicle (자동차 방진고무부품의 피로수명 예측 및 평가)

  • Woo, Chang-Su;Kim, Wan-Doo;Kwon, Jae-Do
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.6
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    • pp.56-62
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    • 2005
  • The fatigue analysis and lifetime evaluation are very important in design procedure to assure the safety and reliability of the rubber components. Fatigue lifetime prediction methodology of the rubber component was proposed by incorporating the finite element analysis and fatigue damage parameter from fatigue test. Finite element analysis of 3D dumbbell specimen and rubber component were performed based on a hyper-elastic material model determined from material test. The Green-Lagrange strain at the critical location determined from the FEM was used for evaluating the fatigue damaged parameter of the natural rubber. Fatigue life of the rubber component are predicted by using the fatigue damage parameter at the critical location. Predicted fatigue lifes of the rubber component agreed fairly well the experimental fatigue lives.

Finite Element Analysis of Mechanical Properties of a Balloon-Expandable Stent (풍선확장식 스텐트의 기계적 특성에 대한 유한요소해석)

  • Oh, Byung-Ki;Cho, Hae-Yong;Kim, Yong-Yun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.7
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    • pp.915-922
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    • 2004
  • A stent is small tube-like structure expanded into stenotic arteries to restore blood flow. The stent expansion behaviors define the effectiveness of the surgical operation. In this paper, finite-element method was employed to analyze expansion behaviors and fatigue life of a typical diamond-shaped balloon-expandable stent. Beyond safety considerations, this type of analysis provides mechanical properties that are often difficult to obtain by experiments. Mechanical properties of the stent expansion pressure, radial recoil, longitudinal recoil and foreshortening were simulated using commercial FEM code, ANSYS and fatigue life were estimated using NISAII ENDURE. The FEM results showed that the pressures necessary to expand the stent up to a diameter of 3mm, 4mm and 5mm were 0.75MPa, 0.82MPa and 0.97MPa. The fatigue lifes according to expansion diameter were 114${\times}$10$^{7}$cycles, 714${\times}$$^{6}$cycles and 163${\times}$10$^{6}$cycles. As a result, a finite element model used in this study can simulate expansion behaviors of stents and should be useful to design new stents or analyze actual stents.

On Shrinkage Cavities Shape Modeling for Fatigue Simulation of A356 Alloy Specimen (A356 합금 시편의 수축공 결함형상에 대한 피로해석용 형상 모델링 방법)

  • Kwak, Si-Young;Cho, In-Sung
    • Journal of Korea Foundry Society
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    • v.39 no.1
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    • pp.1-6
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    • 2019
  • During the casting process, it is possible to minimize shrinkage and blowholes by modifying the casting design. However, it is impossible to eliminate these factors completely. Therefore, mechanical design engineers apply a sufficient safety factor owing to the possibility of insufficient performances of the cast products. In this paper, prediction method of the fatigue life of cast products containing shrinkage is conducted by using CT (computed tomography) and the SSM (shape simplification method), and additional fatigue analyses are carried out. The analysis results are then compared to results from actual experiments on samples with shrinkage defects. It is found to be that the considering actual shrinkage in cast products by means of stress and fatigue analyses is more accurate and effective. It is also considered that the proposed hot spot method provides us a good tool to predict the fatigue lifes of cast product.

A Testing Technique based on Virtual Prototype for Embedded Software (가상 프로토타입 기반 임베디드 소프트웨어의 테스트 기법)

  • Ryu, Hodong;Jeong, Sooyong;Lee, Sunghee;Kim, Jihun;Park, Heungjun;Lee, Seungmin;Lee, Woo Jin
    • IEMEK Journal of Embedded Systems and Applications
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    • v.9 no.6
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    • pp.307-314
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    • 2014
  • Recently, software reliability and safety issues are seriously considered since failures of embedded systems may cause the damages of human lifes. For verifying and testing embedded software, execution environment including sensors and actuators should be prepared in the actual plants or virtual forms on PC. In this paper, we provide the virtual prototype based code simulation techniques and testing framework on PC. Virtual prototypes are generated by combining the Adobe's Flash SWF images corresponding to the state machine of HW or environment components. Code simulation on PC is possible by replacing the device drivers into virtual drivers which connect to virtual prototypes. Also, testing is performed by controlling the states of virtual prototype and simulators. By using these tools, embedded software can be executed in the earlier development phase and the efficiency and SW quality can be enhanced.