• Title, Summary, Keyword: stress measurement

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Effect of Wall Groove Characteristics on Yield Stress Measurement of Magnetorheological Fluid

  • Tian, Zuzhi;Guo, Chuwen;Chen, Fei;Wu, Xiangfan
    • Journal of Magnetics
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    • v.22 no.2
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    • pp.281-285
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    • 2017
  • To suppress the wall slip effect and improve the yield stress measurement precision of magnetorheological fluid, measurement disks with different grooves are first manufactured. Then, the influence of groove characteristics on the yield stress of magnetorheological fluid is investigated by the method of experiments. Finally, the optimization wall grooves of measurement disks are obtained, and the yield stress of a self-prepared magnetorheological fluid is measured. Results indicate that the groove type and groove width have a slight influence on the shear yield stress, whereas the measured yield stress increases with enhanced groove density, and the optimized groove depth is 0.3 mm. The measured shear yield stress of self-prepared MR fluid can be improved by 18 % according to the optimized grooved disks, and the maximum yield stress can reach up to 65 kPa as the magnetic flux density is 0.5 T.

A Study of Residual Stress Measurement in the Weld of Nuclear Materials (원전재료 모재 및 용접부 잔류응력측정 연구)

  • Lee, Kyoung-Soo;Lee, Jeong-Keun;Lee, Seong-Ho;Park, Jae-Hak
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.7 no.1
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    • pp.9-16
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    • 2011
  • Primary water stress corrosion cracking (PWSCC) has been found in the weld region of the nuclear power plant. Welding can produce tensile residual stress. Tensile residual stress contributes to the initiation and growth of PWSCC. It is important to estimate weld residual stress accurately to predict or prevent the initiation and growth of PWSCC. This paper shows the results of finite element analysis and measurement experiment for weld residual stress. For the study, four kinds of specimen were fabricated with the materials used in the nuclear power plant. Residual stresses were measured by four kinds of methods of hole drilling, x-ray diffraction, instrumented indentation and sectioning. Through the study, numerical analysis and measurement results were compared and the characteristics of each measurement technique were observed.

Evaluation of Strength and Residual Stress in $Si_3N_4/SUS304$ Joint ($Si_3N_4/SUS304$ 접합재의 잔류응력 및 강도평가)

  • 박영철;오세욱;조용배
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.1
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    • pp.101-112
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    • 1994
  • The measurement of residual stress distribution of $Si_3N_4/SUS304$ joint was performed on 23 specimens with the same joint condition using PSPC type X-ray stress measurement system and the two-dimensional elastoplastic analysis using finite element method was also attempted. As results, residual stress distribution near the interface on the ceramic side of the joint was revealed quantitatively. Residual stress on the ceramic side of the joint was turned out to be tensional near the interface, maximum along the edge, varying in accordance with the condition of the joint and variance to be most conspicuous for the residual stress normal to the interface characterized by the stress singularities. In the vicinity of the interface, the high stress concentration occurs and residual stress distributes three-dimensionally. Therefore, the measured stress distribution differed remarkably from the result of the two-dimensional finite-element analysis. Especially at the center of the specimen near the interface, the residual stress, $\sigma_{x}$ obtained from the finite element analysis was compressive, whereas measurement using X-ray yielded tensile $\sigma_{x}$. Here we discuss two dimensional superposition model the discrepancy between the results from the two dimensional finite element analysis and X-ray measurement.

Stress Multi-Index Analysis Expression Technique (스트레스 멀티지수 분석 표현기법)

  • Han, Seung-Heon;Kim, Young-Kil
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.12 no.10
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    • pp.1717-1722
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    • 2008
  • A number of tools and equipment can measure the degree of stress. Stress measurement includes both psychological and physiological measurements. Considering only one of these elicits subjective or objective deficiency. Overcoming this problem requires a new stress index that combines these two measurements. Following people's personal traits, the measurement results also appear in diverse ways, but we can consider and study the general case obtained on the basis of the measurement tool. By using the index obtained by the psychological and physiological measurement tools, we obtain an integrated stress index. Therefore, we choose to use four stress measurement tools. The index of the result of each measurement tools is referred to as the multi-index. These indices are plotted on coordinates to analyze and diagnose the balance and tendency of the stress.

Design of a Stress Measurement System for State Recognition of Game Addicts

  • Park, Myeong-Chul;Jung, Hyon-Chel;Kim, Tae-Sun
    • Journal of the Korea Society of Computer and Information
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    • v.22 no.6
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    • pp.87-93
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    • 2017
  • In this paper, we design a small low power single channel ECG(Electrocardiogram) system of Chest Belt type with fiber-type electrodes to measure emotional state change of game addict. HRV(Heart Rate Variability) is analyzed through heart rate signal measurement and the psychological stress state is judged by using it. And it verifies its effectiveness through prototype. First, we design HR measurement module through low power MCU(Micro Controller Unit) and implement prototype level measurement system. The results showed that the difference between the addiction group and the general group was confirmed and that the system was effective. The result of this study can be used for health management such as reduction of stress of the user through music and breathing that lowers the stress by detecting the stress state of the general person or the chronic ill person.

Stress Measurement of films using surface micromachined test structures (표면 미세 가공된 구조체를 이용한 박막의 응력 측정)

  • 이창승;정회환;노광수;이종현;유형준
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.721-725
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    • 1996
  • The microfabricated test structures were used in order to evaluate the stress characteristics in films. The test structures were fabricated using surface micromachining technique, including HF vapor phase etching as an effective release method. The fabricated structures were micro strain gauge, cantilever-type vernier gauge and bridge for stress measurement, and cantilever for stress gradient measurement. The strain was measures by observing the deformation of the structures occurred after release etching and the amount of deformation can be detected by micro vernier gauge, which has gauge resolution of 0.2${\mu}{\textrm}{m}$. The detection principles and the degree of precision for the measured strain were also discussed. The characteristics of residual stress in LPCVD polysilicon films were studied using these test structures. The stress gradient due to the stress variation through the film thickness was calculated by measuring the deflection at the cantilever free end.

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DESIGN OF A VIBRATION AND STRESS MEASUREMENT SYSTEM FOR AN ADVANCED POWER REACTOR 1400 REACTOR VESSEL INTERNALS COMPREHENSIVE VIBRATION ASSESSMENT PROGRAM

  • Ko, Do-Young;Kim, Kyu-Hyung
    • Nuclear Engineering and Technology
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    • v.45 no.2
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    • pp.249-256
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    • 2013
  • In accordance with the US Nuclear Regulatory Commission (US NRC), Regulatory Guide 1.20, the reactor vessel internals comprehensive vibration assessment program (RVI CVAP) has been developed for an Advanced Power Reactor 1400 (APR1400). The purpose of the RVI CVAP is to verify the structural integrity of the reactor internals to flow-induced loads prior to commercial operation. The APR1400 RVI CVAP consists of four programs (analysis, measurement, inspection, and assessment). Thoughtful preparation is essential to the measurement program, because data acquisition must be performed only once. The optimized design of a vibration and stress measurement system for the RVI CVAP is essential to verify the integrity of the APR1400 RVI. We successfully designed a vibration and stress measurement system for the APR1400 RVI CVAP based on the design materials, the hydraulic and structural analysis results, and performance tests of transducers in an extreme environment. The measurement system designed in this paper will be utilized for the APR1400 RVI CVAP as part of the first construction project in Korea.

Development of 3-Dimensional Stress Measurement System by Bore hole Bottom Deformation Method (공저변형법에 의한 3차원응력측정 시스템의 개발)

  • Lee, Ki-Ha;Ishijima, Yoji;Fujii, Yoshiaki
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.34-41
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    • 2006
  • A 3-dimensional stress measurement system based on the bore hole bottom deformation method, which is one of the stress relief methods, was developed. A pilot bore hole is drilled from the bottom of a bore hole and the stress meter is inserted into the pilot bore hole in the method. The bore hole is advanced as an over coring and the deformations in seven directions are measured by cantilever type-sensors. Using the cantilever type-sensors saves time for hardening of glue. No cable connection between the stress meter and a data logger is necessary since a compact data logger is installed in the stress meter. The accuracy of the stress meter was confirmed by a biaxial test for a Shikotsu welded tuff block although in-situ tests have not been carried out yet.

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A Review on the Job Stress Measurements in Nuclear Power Plant Workers for Human Error Prevention

  • Kim, Seon Soo;Luo, Meiling;Oh, Yeon Ju;Lee, Yong Hee
    • Journal of the Ergonomics Society of Korea
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    • v.32 no.1
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    • pp.47-58
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    • 2013
  • Objective: The aim of this study is to review the job stress measurement for applying in nuclear power plants(NPPs). Background: The standard and guideline to evaluate and manage the job stress is insufficient in NPPs. Although job stress might have a negative effect on task performance particularly it can be related with human error in NPPs. Method/Results: This paper considered the objective and subjective stress measurements. One of the questionnaire(Korean Occupational Stress Scale) and the experiment method was investigated to apply in NPPs. KOSS was analyzed about the inter item consistency and correlation with the workload, and relative importance. In the objective evaluation considered the experiment method for the physical and mental job stress and analyzed from the phased point of view. Conclusion/Application: The measurement and criteria to evaluate job stress for operators must be complemented on the job characters and environments in NPPs. This study may support to confirm and manage the job stress in NPPs. The study of more specific methodology on job stress in NPPs is required on the basis of this paper.

Characteristics of Excessive Horizontal Stress in Korea by Hydraulic Fracturing Stress Measurement (수압파쇄법에 의한 국내 과잉 수평응력 분포 특성에 관한 연구)

  • Bae, Seong-Ho;Jeon, Seok-Won;Kim, Hak-Soo;Kim, Jae-Min
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.431-438
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    • 2005
  • In this paper, the characteristics of excessive horizontal stress components in Korea were studied using the in-situ hydraulic fracturing stress measurement data over five hundred in 110 individual test boreholes. Based on the in-situ testing data, the magnitude and orientation of the horizontal stress component and variation of stress ratio (K) with depth were investigated. And also horizontal stress magnitude versus depth relationships and distribution limits of stress ratio components were suggested. For the subsurface space above 310 m depth in the entire territory, the stress ratio has a tendency to diminish and be stabilized with depth, but for some areas, it was revealed that the excessive horizontal stress fields with stress ratio close to 3.0 below 200 m in depth have formed. The result of investigation for excessive horizontal stress regions indicates that there exist several regions above 300 m in depth where localized excessive horizontal stresses enough to induce potentially brittle failure around future openings have formed.

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