• Title, Summary, Keyword: In situ measurement system

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In-situ fatigue monitoring procedure using nonlinear ultrasonic surface waves considering the nonlinear effects in the measurement system

  • Dib, Gerges;Roy, Surajit;Ramuhalli, Pradeep;Chai, Jangbom
    • Nuclear Engineering and Technology
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    • v.51 no.3
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    • pp.867-876
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    • 2019
  • Second harmonic generation using nonlinear ultrasonic waves have been shown to be an early indicator of possible fatigue damage in nuclear power plant components. This technique relies on measuring amplitudes, making it highly susceptible to variations in transducer coupling and instrumentation. This paper proposes an experimental procedure for in-situ surface wave nonlinear ultrasound measurements on specimen with permanently mounted transducers under high cycle fatigue loading without interrupting the experiment. It allows continuous monitoring and minimizes variation due to transducer coupling. Moreover, relations describing the effects of the measurement system nonlinearity including the effects of the material transfer function on the measured nonlinearity parameter are derived. An in-situ high cycle fatigue test was conducted using two 304 stainless steel specimens with two different excitation frequencies. A comprehensive analysis of the nonlinear sources, which result in variations in the measured nonlinearity parameters, was performed and the effects of the system nonlinearities are explained and identified. In both specimens, monotonic trend was observed in nonlinear parameter when the value of fundamental amplitude was not changing.

Development of Error Compensation Algorithm for Image based Measurement System (미세부품 영상 측정시 진동에 의한 오차 보상 알고리즘 개발)

  • Pyo Chang Ryul
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.10
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    • pp.102-108
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    • 2004
  • In this paper, we studied a vibration problem that is critical and common to most precision measurement systems. For micro mechanical part measurements, results obtained from the vision-based precision measurement system may contain errors due to the vibration. In order to defeat this generic problem, for the current study, a PC based image processing technique was used first, to assess the effect of the vibration to the precision measurement and second, to develop an in-situ calibration algorithm that automatically compensate the measurement results in real time. We used a set of stereoscopic CCD cameras to acquire the images for the dimensional measurement and the reference measurement. The mapping function was obtained through the in-situ calibration to compensate the measurement results and the statistical analysis for the actual results is provided in the paper. Based on the current statistical study, it is expected to obtain high precision results for the micro measurement systems.

System Identification of In-situ Vehicle Output Torque Measurement System (차량 출력 토크 측정 시스템의 시스템 식별)

  • Kim, Gi-Woo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.2
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    • pp.85-89
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    • 2012
  • This paper presents a study on the system identification of the in-situ output shaft torque measurement system using a non-contacting magneto-elastic torque transducer installed in a vehicle drivline. The frequency response (transfer) function (FRF) analysis is conducted to interpret the dynamic interaction between the output shaft torque and road side excitation due to the road roughness. In order to identify the frequency response function of vehicle driveline system, two power spectral density (PSD) functions of two random signals: the road roughness profile synthesized from the road roughness index equation and the stationary noise torque extracted from the original torque signal, are first estimated. System identification results show that the output torque signal can be affected by the dynamic characteristics of vehicle driveline systems, as well as the road roughness.

Application of Real-Time Monitoring System to In-Situ Soil Remediation Project (원위치 지반오염정화사업에서의 실시간 모니터링 시스템의 적용 사례)

  • Jung, Seung-Yong;Kim, Byung-Il;Han, Sang-Jae;Kim, Soo-Sam;Hong, Sang-Ki
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1384-1389
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    • 2005
  • A real-time monitoring system for in-situ soil remediation technologies is developed and then applied to electrokinetic remediation technique in the field trial tests during 150days. The developed system is consisted the controlled program based on internet web page, data logger, measurement instruments and so on. In the measured items there are pH, temperature, electrical current and potential, vacuum pressure. The results indicated that the system is successively applied to electrokinetic remediation technique, and further research considering economic view and multi purpose system for in-situ soil remediation technologies is needed.

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Analysis of In-Situ Stress Regime from Hydraulic Fracturing Field Measurements in Korea (수압파쇄 현장시험을 통한 국내 지반의 초기응력 분포양상 해석)

  • Choi, Sung-Oong
    • Journal of Industrial Technology
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    • v.28 no.B
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    • pp.111-116
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    • 2008
  • Since the hydraulic fracturing field testing method was introduced first to Korean geotechnical engineers in 1994, there have been lots of progresses in a hardware system as well as an interpretation tool. The hydrofracturing system of first generation was the pipe-line type, and it has been developed to a wire-line system at their second generation. The current up-to-date system is more compact and is able to be operated by all-in-one system. With a progress in a hardware system, the software for analyzing in-situ stress regime has also been progressed. The shut-in pressure, which is the most ambiguous parameter to be obtained from hydrofracturing pressure curves, can now be acquired automatically from the various methods. While the hardware and software for hydrofracturing tests are being developed during the last decade, the author could accumulate the field test results which can cover the almost whole area of South Korea. Currently these field data are used widely in a feasibility study or a preliminary design step for tunnel construction in Korea. Regarding the difficulties in a site selection and a test performance for the in-situ stress measurement at an off-shore area, the in-situ stress regime obtained from the field experiences in the land area can be used indirectly for the design of a sub-sea tunnel. From the hydrofracturing stress measurements, the trend of magnitude and direction of in-situ stress field was shown identically with the geological information in Korea.

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A Decade's Experiences on the Hydrofracturing In-Situ Stress Measurement for Tunnel Construction in Korea (암반터널 설계를 위한 수압파쇄 초기지압 측정의 10여년 간의 경험)

  • Choe, Seong-Ung;Park, Chan;Sin, Jung-Ho;Sin, Hui-Sun
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • pp.79-88
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    • 2008
  • Since the hydraulic fracturing field testing method was introduced first to Korean geotechnical engineers in 1994, there have been lots of progresses in a hardware system as well as an interpretation tool. The hydrofracturing system of first generation was the pipe-line type, so it was not easy to handle. It had been modified to a wire-line system at their second generation. It was more compact one but it also needed an additional air-compressor. Our current system is much more compact and operated by all-in-one system, so it doesn't need an additional air-compressor. With a progress in a hardware system, the software for analyzing the in-situ stress regime has also been progressed. For example, the shut-in pressure, which is the most ambiguous parameter to be obtained from hydrofracturing pressure curves, can now be acquired automatically from the various methods. While the hardware and software for hydrofracturing tests are being developed during the last decade, the author could accumulate the field test results which can cover the almost whole area of South Korea. Currently these field data are used widely in a feasibility study or a preliminary design step for tunnel construction in Korea. Regarding the difficulties in a site selection and a test performance for the in-situ stress measurement at an off-shore area, the in-situ stress regime obtained from the field experiences in the land area can be used indirectly for the design of a sub-sea tunnel. From the hydrofracturing stress measurements, the trend of magnitude and direction of in-situ stress field was shown identically with the geological information in Korea.

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Assessment of the Radiological Inventory for the Reactor at Kori NPP Using In-Situ Measurement Technology (In-Situ 측정법을 이용한 고리 원자로 방사선원항 평가)

  • Jeong, Hyun Chul;Jeong, Sung Yeop
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.12 no.2
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    • pp.171-178
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    • 2014
  • After the expiration of operating license of a plant, all infrastructures within the plant must be safely dismantled to the point that it no longer requires measures for radiation protection. Despite the fact that Kori 1 and Wolsong 1 are close to the expiration of their operating license, sufficient technologies for radiological characterization, decontamination and dismantling is still under development. The purpose of this study is to develop one of methods for radiological inventory assessment on measuring object by using direct measure of large component with In-Situ measurement technique. Radiological inventory was assessed by analyzing nuclide using portable gamma spectroscopy without dismantling reactor head, and the result of direct measurement was supplemented by performing indirect measurement. Radiochemical analysis were performed on surface contamination samples as well. During the study, radiological inventory of reactor vessel calculated expanding the result. Based on the result and the radioactivity variation of each radionuclides time frame for decommissioning can be decided. Thus, it is expected that during the decommissioning of plants, the result of this study will contribute to the reduction of radiation exposure to workers.

Fundamental approach to development of plastic scintillator system for in situ groundwater beta monitoring

  • Lee, UkJae;Choi, Woo Nyun;Bae, Jun Woo;Kim, Hee Reyoung
    • Nuclear Engineering and Technology
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    • v.51 no.7
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    • pp.1828-1834
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    • 2019
  • The performance of a plastic scintillator for use in an in situ measurement system was analyzed using simulation and experimental methods. The experimental results of four major pure beta-emitting radionuclides, namely $^3H$, $^{14}C$, $^{32}P$, and $^{90}Sr/^{90}Y$, were compared with those obtained using a Monte Carlo N-particle (MCNP) code simulation. The MCNP simulation and experimental results demonstrated good agreement for $^{32}P$ and $^{90}Sr/^{90}Y$, with a relative difference of 1.95% and 0.43% between experimental and simulation efficiencies for $^{32}P$ and $^{90}Sr/^{90}Y$, respectively. However, owing to the short range of beta particles in water, the efficiency for $^{14}C$ was extremely low, and $^3H$ could not be detected. To directly measure the low-energy beta radionuclides considering their short range, a system where the source could flow directly to the scintillator was developed. The optimal thickness of the plastic scintillator was determined based on the suggested diameter. Results showed that the detection efficiency decreases with an increase in the depth of the water. The detection efficiency decreased drastically to approximately 10 cm, and the tendency was gradually constant.

Real-time X-ray Scattering as a Nanostructure Probe for Organic Photovoltaic Thin Films

  • Lee, Hyeon-Hwi;Kim, Hyo-Jeong;Kim, Jang-Ju
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.181-181
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    • 2013
  • Recently, nanostructure and the molecular orientation of organic thin films have been largely paid attention due to its importance in organic electronics such as organic thin film transistors (OTFTs), organic light emitting diodes (OLEDs), and organic photovoltaics (OPVs). Among various methods, the diffraction and scattering techniques based on synchrotron x-rays have shown powerful results in organic thin film systems. In this work, we introduce the in-situ annealing system installed at PLS-II (Pohang Light Source II) for organic thin films by simultaneously conducting various x-ray scattering measurements of x-ray reflectivity, conventional x-ray scattering, grazing incidence wide angle x-ray scattering (GI-WAXS) and so on. Using the in-situ measurement, we could obtain real time variation of nanostructure as well as molecular orientation during thermal annealing in metal-phthalocyanine thin films. The variation of surface and interface also could be simultaneously investigated by the x-ray reflectivity measurement.

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A Study on the Behavior Prediction of Underground Structures by Back Analysis (역해석에 의한 지하구조체의 거동예측에 관한 연구)

  • 장정범;김문겸
    • Tunnel and Underground Space
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    • v.8 no.2
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    • pp.139-145
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    • 1998
  • The reliable estimation of the system parameters and the accurate prediction of the system behavior are important to design underground structures safely and economically. Especially, the elastic modulus and the in-situ stresses are very important parameters in predicting the behavior of the underground structure. Therefore, the back analysis using the field measurement data is developed to determine accurately the elastic modulus and the in-situ stresses of the underground structural system in this study. A back analysis using the combined finite and boundary element is developed. It can consider the far field boundary condition and is efficient in computation. In this study, a back analysis is performed to predict behaviors of underground structures for the real construction site. The comparison between the results of the back analysis with field measurement data and the obtained material properties from the field test shows good agreement for the real construction site.

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