• 산업공학
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• 제24권1호
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• pp.8-14
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• 2011

Principal Component Analysis (PCA) reduces the dimensionality of the process by creating a new set of variables, Principal components (PCs), which attempt to reflect the true underlying process dimension. However, for highly nonlinear processes, this form of monitoring may not be efficient since the process dimensionality can't be represented by a small number of PCs. Examples include the process of semiconductors, pharmaceuticals and chemicals. Nonlinear correlated process variables can be reduced to a set of nonlinear principal components, through the application of Kernel Principal Component Analysis (KPCA). Support Vector Data Description (SVDD) which has roots in a supervised learning theory is a training algorithm based on structural risk minimization. Its control limit does not depend on the distribution, but adapts to the real data. So, in this paper proposes a non-linear process monitoring technique based on supervised learning methods and KPCA. Through simulated examples, it has been shown that the proposed monitoring chart is more effective than $T^2$ chart for nonlinear processes.

• Structural Monitoring and Maintenance
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• 제1권3호
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• pp.339-356
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• 2014

This study has been motivated to evaluate the practicality of numerical simulation of impedance monitoring for damage detection in steel column connection. In order to achieve the objective, the following approaches are implemented. Firstly, the theory of electro-mechanical (E/M) impedance responses and impedance-based damage monitoring method are outlined. Secondly, the feasibility of numerical simulation of impedance monitoring is verified for several pre-published experimental examples on steel beams, cracked aluminum beams, and aluminum round plates. Undamaged and damaged steel and aluminum beams are simulated to compare to experimental impedance responses. An aluminum round plate with PZT patch in center is simulated to investigate sensitive range of impedance responses. Finally, numerical simulation of the impedance-based damage monitoring is performed for a steel column connection in which connection bolts are damaged. From the numerical simulation test, the applicability of the impedance-based monitoring to the target steel column connection can be evaluated.

• 제어로봇시스템학회논문지
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• 제7권7호
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• pp.632-639
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• 2001

This paper proposes an improved architecture of web-based monitoring systems for monitor of processes in plants from the soft real-time point of view. The suggested model is designed to be able to guarantee the temporal and spatial consistency and transmit the monitoring data periodically via the intranet and the Internet. The model generates one thread for monitoring management, one DB thread, one common memory, and corresponding monitoring threads to clients. The monitoring thread is executed during the smaller time than the execution time of the process used in the conventional methods such as CGI and servlet method. The Java API for the server API, VRML, EAI(External Authoring Interface) and Java Applets for efficient dimensional WEB monitoring are used. The proposed model is implemented and tested for a FMS plant, Some examples show that the proposed model is useful one.

• Structural Monitoring and Maintenance
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• 제3권3호
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• pp.233-257
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• 2016

This paper provides an overview on development of long-span bridges monitoring in Japan, with emphasis on monitoring strategies, types of monitoring system, and effective utilization of monitoring data. Because of severe environment condition such as high seismic activity and strong wind, bridge monitoring systems in Japan historically put more emphasis on structural evaluation against extreme events. Monitoring data were used to verify design assumptions, update specifications, and facilitate the efficacy of vibration control system. These were among the first objectives of instrumentation of long-span bridges in a framework of monitoring system in Japan. Later, monitoring systems were also utilized to evaluate structural performance under various environment and loading conditions, and to detect the possible structural deterioration over the age of structures. Monitoring systems are also employed as the basis of investigation and decision making for structural repair and/or retrofit when required. More recent interest has been to further extend application of monitoring to facilitate operation and maintenance, through rationalization of risk and asset management by utilizing monitoring data. The paper describes strategies and several examples of monitoring system and lessons learned from structural monitoring of long-span bridges in Japan.

• 센서학회지
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• 제24권5호
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• pp.281-286
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• 2015

The importance of air quality monitoring is rapidly increasing. Even though state-of-the-art air quality monitoring technologies such as mass spectrometry, gas chromatography, and optical measurement enable high-fidelity measurement of air pollutants, they cannot be widely used for portable or personalized platforms because of their high cost and complexity. Recently, personalized and localized environmental monitoring, rather than global and averaged environmental monitoring, has drawn greater attention with the advancement of mobile telecommunication technologies. Here, micro- and nano-technologies enable highly integrated and ultra-compact sensors to meet the needs of personalized environmental monitoring. In this paper, several examples of MEMS-based gas sensors for compact and personalized air quality monitoring are explained. Additionally, the principles and usage of functional nanomaterials are discussed for highly sensitive and selective gas sensors.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.285-292
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• 2004

Earth Anchor method as a supporting system is widely used in the large scale deep excavation of urban areas or slope excavation project. Considering the application frequency of that method and catastrophe of that method under unproper construction management, we can find out many problems relevant to the domestic design and construction management of earth anchor method. When we encounter the cases of rapid increments and various decrements in earth anchor axial forces, considering the characteristic of earth anchor method, it is an essential point to catch the reasons and to prepare countermeasures. This article introduces two actual monitoring examples based on the close analyses of measured data in a typical large scale deep excavation project and slope excavation project. One is a rapidly increasing case of earth anchor axial forces with the continuous advance of incremental deformation in a geological layer interface. And another is a decreasing case of earth anchor axial forces with the construction conditions. The effort of this article aims to improve and develop the technique of design and construction in the coming projects having similar ground condition and supporting method.

• Journal of the Korean Data and Information Science Society
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• 제14권4호
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• pp.939-950
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• 2003

Control charts are very useful tool for monitoring of process characteristics. This paper discusses the problem of design of control limits when the subgroups are composed by cluster sampling type. As an alternative method of design of control limits XbBar chart is proposed, which uses the control limits based on the variation between subgroups instead of using classical variation within subgroups. Two examples are presented for reasonable design of control limits and conditions of subgroups based on the cluster sampling. Through examples the guidelines for making proper control limits are proposed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2612-2616
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• 2003

Method for performance monitoring and diagnosis of a MIMO control system has been studied aiming at application to model predictive control (MPC) for industrial processes. The performance monitoring part is designed on the basis of the traditional SPC/SQC method. To meet the underlying premise of Schwart chart observation that the observed variable should be univariate and independent, the process variables are decorrelated temporally as well as spatially before monitoring. The diagnosis part was designed to identify the root of performance degradation among the controller, process, and disturbance. For this, a method to estimate the model-error and disturbance signal has been devised. The proposed methods were evaluated through numerical examples.

• 대한예방의학회:학술대회논문집
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• 대한예방의학회 1994년도 교수 연수회(역학)
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• pp.332-335
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• 1994

Compared to other variables being considered in therapeutics, patient compliance has long been given minor attention although it affects every aspect of medical care; Limited methodology of compliance measurement, in particular, has hampered major progress in research, and pre-conceptions have been reiterated. However, there is a recent surge in interest derived from new data revealed by reliable methods, i.g. continuous medication (compliance) monitoring. The visualization of dynamics in drug regimen compliance over time offers unique opportunities, both to scientific drug evaluation and therapeutics in medical practice. New perspectives related to the descriptive and explanatory side of the problem are outlined by giving examples from various therapeutic fields.

• 콘크리트학회논문집
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• 제14권3호
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• pp.341-348
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• 2002

유지관리 계측은 터널 구조물의 지속적인 안전성 확인과 최적의 유지관리가 되도록 객관적이고 연속적인 자료제공을 목적으로 한다. 최근 들어 각종 터널에 적용하는 사례가 급속하게 증가되고 있으나, 현재까지 터널에서 장기간 측정된 계측실적도 적고, 합리적인 분석방법 연구도 전무한 실정이다. 본 연구에서는 장기간 계측이 수행된 지하철 풍화대 통과 터널의 계측결과를 회귀분석하여 터널의 최종 지보재인 콘크리트 라이닝의 응력과 철근응력의 상관관계를 파악하였다. 또한, 터널 콘크리트 라이닝의 응력과 안전성의 분석을 통하여 유지관리 계측 빈도 및 관리 기준치의 현장 적용성을 검토하였다.