• Title/Summary/Keyword: in situ monitoring

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A Study for plasma nonuniformity measurement by PDM Tool (PDM Tool을 이용한 plasma nonuniformity 측정에 관한 연구)

  • 김상용;서용진;이우선;정헌상;김창일;장의구
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.07a
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    • pp.75-78
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    • 2000
  • This paper is estimated to enhance yield improvement and device reliability using PDM(plasma damage monitoring) system capable of in-suit detection about plasma nonuniformity. PDM Tool is the non-contact method of wafer and surface potential electrode(kelvin probe). Its tool measures Vox(oxide barrier) with charge created by plasma. It's possible to inspect the wafer damage generated by plasma charge and analysis of in-situ monitoring data. we obtained the good data which is continuously prevented from plasma damage using its tool for 10weeks. This tool is contributed to preventive steps contemporaneously inspecting the difference of inter-chamber.

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Real time control of the growth of Ge-Sb-Te multi-layer film as an optical recording media using in-situ ellipsometry (In-situ ellipsometry를 사용한 광기록매체용 Ge-Sb-Te 다층박막성장의 실시간 제어)

  • 김종혁;이학철;김상준;김상열;안성혁;원영희
    • Korean Journal of Optics and Photonics
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    • v.13 no.3
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    • pp.215-222
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    • 2002
  • Using an in-situ ellipsometer, we monitored the growth curve of optical recording media in real time. For confirmation of the thickness control using in-situ ellipsometry, we analyzed the deposited multi-layer sample made of Ge-Sb-Te alloy film and ZnS-Si0$_2$ dielectric films using an exsitu spectroscopic ellipsometer. The target material in the first sputtering gun is ZnS-SiO$_2$ as the protecting dielectric layer and that in the second gun is Ge$_2$sb$_2$Te$_{5}$ as the receding layer. While depositing ZnS-SiO$_2$, Ge$_2$Sb$_2$Te$_{5}$ and ZnS-SiO$_2$ films on c-Si substrate in sequence, we measured Ψ $\Delta$ in real time. Utilizing the complex refractive indices of Ge$_2$Sb$_2$Te$_{5}$ and ZnS-SiO$_2$ obtained from the analysis of spectroscopic ellipsometry data, the evolution of ellipsometric constants Ψ, $\Delta$ with thickness is calculated. By comparing the calculated evolution curve of ellipsometric constants with the measured one, and by analyzing the effect of density variation of the Ge$_2$Sb$_2$Te$_{5}$ recording layer on ellipsometric constants with thickness, we precisely monitored the growth rate of the Ge-Sb-Te multilayer and controlled the growth process. The deviation of the real thicknesses of Ge-Sb-Te multilayer obtained under the strict monitoring is post confirmed to be less than 1.5% from the target structure of ZnS-SiO$_2$(1400 $\AA$)IGST(200 $\AA$)$\mid$ZnS-SiO$_2$(200$\AA$).(200$\AA$).

Assessment of temperature effect in structural health monitoring with piezoelectric wafer active sensors

  • Kamas, Tuncay;Poddar, Banibrata;Lin, Bin;Yu, Lingyu
    • Smart Structures and Systems
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    • v.16 no.5
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    • pp.835-851
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    • 2015
  • This paper presents theoretical and experimental evaluation of the structural health monitoring (SHM) capability of piezoelectric wafer active sensors (PWAS) at elevated temperatures. This is important because the technologies for structural sensing and monitoring need to account for the thermal effect and compensate for it. Permanently installed PWAS transducers have been One of the extensively employed sensor technologies for in-situ continuous SHM. In this paper, the electro-mechanical impedance spectroscopy (EMIS) method has been utilized as a dynamic descriptor of PWAS behavior and as a high frequency standing wave local modal technique. Another SHM technology utilizes PWAS as far-field transient transducers to excite and detect guided waves propagating through the structure. This paper first presents how the EMIS method is used to qualify and quantify circular PWAS resonators in an increasing temperature environment up to 230 deg C. The piezoelectric material degradation with temperature was investigated and trends of variation with temperature were deduced from experimental measurements. These effects were introduced in a wave propagation simulation software called Wave Form Revealer (WFR). The thermal effects on the substrate material were also considered. Thus, the changes in the propagating guided wave signal at various temperatures could be simulated. The paper ends with summary and conclusions followed by suggestions for further work.

On the underground imaging using borehole camera

  • Jeong Yun-Young;Nakagawa Hideaki;Shimada Hideki;Matsui Kikuo;Kim JaeDong
    • 한국지구물리탐사학회:학술대회논문집
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    • 2003.11a
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    • pp.52-59
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    • 2003
  • It is only possible through the image analysis of borehole wall and the core recovered from borehole constructed in rock mass that the real information about geologic characteristics in rock mass is directly obtained in primary research. Monitoring apparatus with multi-functional utility has implemented and applied in-situ condition for finding the geologic condition of target area. But, this apparatus is very expensive to be applied at the risk of loss during monitoring and cause hard work for moving them to the determined position. This paper shows the underground imaging from the borehole information obtained by a borehole camera with the simple utility and low cost enough to investigate the characteristics of borehole wall. Monitoring for this has been done in open-pit mine located at the northeastern part of Fukuoka Prefecture in Japan, and finally the three dimensional imaging of geological discontinuity was discussed relative to the field condition.

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Minimum detectable activity of plastic scintillator for in-situ beta measurement system in ground water

  • Choi, Woo Nyun;Lee, UkJae;Bae, Jun Woo;Kim, Hee Reyoung
    • Nuclear Engineering and Technology
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    • v.51 no.4
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    • pp.1169-1175
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    • 2019
  • The minimum detectable activity (MDA) value was derived according to the flow rate of the sample and degree of amplification of the device by sending the sample directly from the collection site to the detection part through a pump. This method can lead to reduction in time and cost compared to the existing measurement method that uses a pre-treatment process. In this study, experiments were conducted on $^3H$ and $^{90}Sr$, which are the major pure beta-emitting radionuclides, by setting the sample flow rate and the amplification gain as factors. The MDA values were derived according to the flow rates, considering that the flow rate can affect the MDA values. There were no change in the MDA under different flow rates of 0, 600, 800, and 1000 mL/min. Therefore, it was confirmed that the flow rate may not be considered when collecting samples for monitoring in actual field. As the degree of amplification of the amplifier increased, the time required to reach the target MDA decreased. When the amplification was quadrupled, the detection efficiency increased by approximately 23.4 times, and the time to reach the MDA decreased to approximately 1/550 times. This method offers the advantage of real-time on-site monitoring.

Vibration-based structural health monitoring for offshore wind turbines - Experimental validation of stochastic subspace algorithms

  • Kraemer, Peter;Friedmanna, Herbert
    • Wind and Structures
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    • v.21 no.6
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    • pp.693-707
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    • 2015
  • The efficiency of wind turbines (WT) is primarily reflected in their ability to generate electricity at any time. Downtimes of WTs due to "conventional" inspections are cost-intensive and undesirable for investors. For this reason, there is a need for structural health monitoring (SHM) systems, to enable service and maintenance on demand and to increase the inspection intervals. In general, monitoring increases the cost effectiveness of WTs. This publication concentrates on the application of two vibration-based SHM algorithms for stability and structural change monitoring of offshore WTs. Only data driven, output-only algorithms based on stochastic subspace identification (SSI) in time domain are considered. The centerpiece of this paper deals with the rough mathematical description of the dynamic behavior of offshore WTs and with the basic presentation of stochastic subspace-based algorithms and their application to these structures. Due to the early stage of the industrial application of SHM on offshore WT on the one side and the required confidentiality to the plant manufacturer and operator on the other side, up to now it is not possible to analyze different isolated structural damages resp. changes in a systematic manner, directly by means of in-situ measurement and to make these "acknowledgements" publicly available. For this reason, the sensitivity of the methods for monitoring purposes are demonstrated through their application on long time measurements from a 1:10 large scale test rig of an offshore WT under different conditions: undamaged, different levels of loosened bolt connections between tower parts, different levels of fouling, scouring and structure inclination. The limitation and further requirements for the approaches and their applicability on real foundations are discussed along the paper.

Internal Strain Monitoring of Filament Wound Pressure Tanks using Embedded Fiber Bragg Grating Sensors (삽입된 광섬유 브래그 격자 센서를 이용한 필라멘트 와인딩된 복합재료 압력탱크의 내부 변형률 모니터링)

  • Kim, C.U.;Park, S.W.;Park, S.O.;Kim, C.G.;Kang, D.H.
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2005.04a
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    • pp.17-20
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    • 2005
  • In-situ structural health monitoring of filament wound pressure tanks were conducted during water-pressurizing test using embedded fiber Bragg grating (FBG) sensors. We need to monitor inner strains during working in order to verify the health condition of pressure tanks more accurately because finite element analyses on filament wound pressure tanks usually show large differences between inner and outer strains. Fiber optic sensors, especially FBG sensors can be easily embedded into the composite structures contrary to conventional electric strain gages (ESGs). In addition, many FBG sensors can be multiplexed in single optical fiber using wavelength division multiplexing (WDM) techniques. We fabricated a standard testing and evaluation bottle (STEB) with embedded FBG sensors and performed a water-pressurizing test. In order to increase the survivability of embedded FBG sensors, we suggested a revised fabrication process for embedding FBG sensors into a filament wound pressure tank, which includes a new protecting technique of sensor heads, the grating parts. From the experimental results, it was demonstrated that FBG sensors can be successfully adapted to filament wound pressure tanks for their structural health monitoring by embedding.

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An Overview of Remote Sensing of Chlorophyll Fluorescence

  • Xing, Xiao-Gang;Zhao, Dong-Zhi;Liu, Yu-Guang;Yang, Jian-Hong;Xiu, Peng;Wang, Lin
    • Ocean Science Journal
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    • v.42 no.1
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    • pp.49-59
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    • 2007
  • Besides empirical algorithms with the blue-green ratio, the algorithms based on fluorescence are also important and valid methods for retrieving chlorophyll-a concentration in the ocean waters, especially for Case II waters and the sea with algal blooming. This study reviews the history of initial cognitions, investigations and detailed approaches towards chlorophyll fluorescence, and then introduces the biological mechanism of fluorescence remote sensing and main spectral characteristics such as the positive correlation between fluorescence and chlorophyll concentration, the red shift phenomena. Meanwhile, there exist many influence factors that increase complexity of fluorescence remote sensing, such as fluorescence quantum yield, physiological status of various algae, substances with related optical property in the ocean, atmospheric absorption etc. Based on these cognitions, scientists have found two ways to calculate the amount of fluorescence detected by ocean color sensors: fluorescence line height and reflectance ratio. These two ways are currently the foundation for retrieval of chlorophyll-a concentration in the ocean. As the in-situ measurements and synchronous satellite data are continuously being accumulated, the fluorescence remote sensing of chlorophyll-a concentration in Case II waters should be recognized more thoroughly and new algorithms could be expected.

Application of smart piezoelectric transducers to structural health monitoring (구조물 건전성 감시를 위한 스마트 PZT센서의 적용성 연구)

  • Park, Seung-Hee;Yi, Jin-Hak;Lee, Jong-Jae;Yun, Chung-Bang;Noh, Yong-Rae
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.10a
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    • pp.549-555
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    • 2003
  • The objective of かis study is to investigate the feasibility of piezoelectric transducers as a damage detection system for civil infrastructures. There have been considerable amount of efforts by the modal analysis community to localize damage and evaluate its severity without looking at a reliable way to excite the structure. The detection of damages by modal analysis and similar vibration techniques depends upon the knowledge and estimation of various modal parameters. In addition to the associated difficulties, such low-frequency dynamic response based techniques fail to detect incipient damages. Smart piezoelectric ceramic (PZT) transducers which act as both actuators and sensors in a self-analyzing manner are emerging to be effective in non-parametric health monitoring of structural systems. In this paper, we present the results of an experimental study for the detection of damages using smart PZT transducers on the steel plate. The method of extracting the impedance characteristics of the PZT transducer, which is electro-mechanically coupled to the host structure, is adopted for damage detection. Two damages are simulated and assessed by the bonded PZT transducers for characterization. The experimental results verified the efficacy of the proposed approach and provided a demonstration of good robustness at the realistic steel structures, emphasizing the great potential for developing an automated in situ structural health monitoring system for application to large civil infrastructures without the need to blow the modal parameters.

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