• Journal of the Korea Concrete Institute
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• v.14 no.3
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• pp.341-348
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• 2002

The purpose of maintenance monitoring is to offer the objective and continuous data in order to be lasting security affirmation and best fitted maintenance of tunnel structure. Though recently the examples of maintenance monitoring which Is applied to tunnel are rapidly increasing, long-term measured monitoring actual results and rationally analysis method researches are wholly lacking. In this study, it is analyzed that the relationship of stress and reinforcement stress of concrete lining, i.e., last support materials of tunnel through regression analysis based on the monitoring result of the subway tunnel, which was accomplished the monitoring for long period, passing the weathering. Also, through the analysis of the stress and the safety of concrete lining, it is estimated that the frequency of maintenance monitoring and the in-situ application of the criteria value of management.

• Journal of Radiation Protection and Research
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• v.41 no.4
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• pp.333-338
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• 2016

Background: In case of radiation emergencies, internal exposure monitoring for the members of public will be required to confirm internal contamination of each individual. In-vivo monitoring technique using portable gamma spectrometer can be easily applied for internal exposure monitoring in the vicinity of the on-site area. Materials and Methods: In this study, minimum detectable doses (MDDs) for $^{134}Cs$, $^{137}Cs$, and $^{131}I$ were calculated adjusting minimum detectable activities (MDAs) from 50 to 1,000 Bq to find out the optimal in-vivo counting condition. DCAL software was used to derive retention fraction of Cs and I isotopes in the whole body and thyroid, respectively. A minimum detect-able level was determined to set committed effective dose of 0.1 mSv for emergency response. Results and Discussion: We found that MDDs at each MDA increased along with the elapsed time. 1,000 Bq for $^{134}Cs$ and $^{137}Cs$, and 100 Bq for $^{131}I$ were suggested as optimal MDAs to provide in-vivo monitoring service in case of radiation emergencies. Conclusion: In-vivo monitoring program for emergency response should be designed to achieve the optimal MDA suggested from the present work. We expect that a reduction of counting time compared with routine monitoring program can achieve the high throughput system in case of radiation emergencies.

• Smart Structures and Systems
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• v.12 no.2
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• pp.209-233
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• 2013

With an annual growth rate of about 30%, wind energy systems, such as wind turbines, represent one of the fastest growing renewable energy technologies. Continuous structural health monitoring of wind turbines can help improving structural reliability and facilitating optimal decisions with respect to maintenance and operation at minimum associated life-cycle costs. This paper presents an integrated monitoring system that is designed to support structural assessment and life-cycle management of wind turbines. The monitoring system systematically integrates a wide variety of hardware and software modules, including sensors and computer systems for automated data acquisition, data analysis and data archival, a multiagent-based system for self-diagnosis of sensor malfunctions, a model updating and damage detection framework for structural assessment, and a management module for monitoring the structural condition and the operational efficiency of the wind turbine. The monitoring system has been installed on a 500 kW wind turbine located in Germany. Since its initial deployment in 2009, the system automatically collects and processes structural, environmental, and operational wind turbine data. The results demonstrate the potential of the proposed approach not only to ensure continuous safety of the structures, but also to enable cost-efficient maintenance and operation of wind turbines.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.109-117
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• 2005

In case of fine machining processes, the cutting state monitoring by a skilled operator is impossible because the physical changes generated during fine machining are very weak. To realize the high efficient and precise fine machining, it is necessary to develop the sensor based monitoring system which is able to detect the fine changes of cutting state. In this paper, the fine acoustic emission monitoring system is developed to monitor the state of the fine machining process. The developed system consists of the AE sensor and the AE signal processing unit. And this has the high-sensitivity and bandwidth which can detect fine AE signal generated during fine machining process. In order to investigate the feasibility of the developed system, evaluation experiments were performed in the fine fixed-abrasive machining processes such as polishing and glass ferrule slicing. Experimental results show that the developed monitoring system possesses an excellent real-time monitoring capability at fine machining processes.

• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.5-9
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• 2019

Optical emission spectroscopy is used to identify chemical species and monitor the changes of process results during the plasma process. However, plasma process monitoring or fault detection by using emission signal variation monitoring is vulnerable to background signal fluctuations. IR heaters are used in semiconductor manufacturing chambers where high temperature uniformity and fast response are required. During the process, the IR lamp output fluctuates to maintain a stable process temperature. This IR signal fluctuation reacts as a background signal fluctuation to the spectrometer. In this research, we evaluate the effect of infrared background signal fluctuation on plasma process monitoring and improve the plasma process monitoring accuracy by using simple infrared background signal subtraction method. The effect of infrared background signal fluctuation on plasma process monitoring was evaluated on $SiO_2$ PECVD process. Comparing the $SiO_2$ film thickness and the measured emission line intensity from the by-product molecules, the effect of infrared background signal on plasma process monitoring and the necessity of background signal subtraction method were confirmed.

• Journal of Drive and Control
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• v.19 no.4
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• pp.29-35
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• 2022

In this paper, we developed a workload index for monitoring the durability test using operation information of an excavator. First, the acceleration and cylinder pressure were selected as load factors by analyzing operation data. Through load correlation analysis according to each load factor, Root Mean Square (RMS) and Work Load Range (WLR) were respectively derived as a load feature representing mechanical load. In addition, the workload index was used to quantify load features. For applying the workload index to monitoring, a real-time monitoring system consisting of sensors and embedded controller was installed on the excavator and the system was integrated with a remote monitoring environment using a wireless network. Results of load monitoring and analysis verified that the developed workload index was effective from the viewpoint of the relative comparison of the workload.

• Korean Journal of Community Nutrition
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• v.22 no.5
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• pp.401-412
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• 2017

Objectives: The purpose of this study was to investigate the current status of parents' monitoring of school lunch programs and to examine the relationship of parents' school lunch monitoring with their level of trust in school lunch programs. Methods: During November 2016, a web survey was conducted with 1,283 parents who had participated in monitoring of school lunch programs. A total of 621 parents completed the questionnaires (48.4% response rate) and the responses from 442 parents were analyzed (34.5% analysis rate) for elementary (n=196) and middle/high school parents (n=246), respectively. Results: Both the elementary and middle/high school parents most wanted to participate in monitoring 1~2 times per month, which was less frequent than their current practice. They showed the highest experience rate in 'food sanitation' area in both the prior training and actual practice of school lunch monitoring. They most responded 'increasing trust in school lunch programs' as a merit and 'lack of parents participating in monitoring' as a problem of school lunch monitoring. The average levels of trust did not differ between elementary and middle/high school parents. Multiple regression analyses showed that elementary school parents' level of satisfaction in the monitored school lunch programs was positively associated with the parents' level of trust in general school lunch programs. Monitoring frequency and parents' age, in addition to level of satisfaction in the monitored school lunch program, were associated with level of trust in general school lunch programs among middle/high school parents. Conclusions: There was room for change in parents' school lunch monitoring programs to meet parents' needs better. Well-managed school lunch monitoring programs contributing to parents' satisfaction with school lunch programs could increase parents' level of trust in school lunch programs.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.717-724
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• 2002

To investigate the behavior of air-shaft and existing tunnel by excavating the small-diameter shaft into the existing tunnel, prototype air-shaft was constructed and analyzed in this study. Geotechnical characterization was conducted by boring and rock cores obtained were tested in the laboratory. Field monitoring including radial and tangential stresses and displacements was conducted with the 3-dimensional numerical analysis of prototype air-shaft. Results of field monitoring were compared with the numerical results. The results showed that maximum displacement of 2.11mm and maximum tangential stress of 54.0 kg/$\textrm{cm}^2$ were obtained during shaft excavation near the right shoulder of the existing tunnel. The comparison of these field measurements with 3-dimensional numerical analysis showed that much more higher stress was measured during excavation compared to the numerical results even though the trends of stress and displacement were similar.

• Environmental Engineering Research
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• v.23 no.4
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• pp.430-441
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• 2018

The adverse health impact of air pollution is becoming more serious. The purpose of this study is twofold: One is to analyze the effect of air pollution and temperatures on human health by analyzing the number of deaths from cardiovascular disease in Seoul, Korea; the other is to determine what impact the location of a monitoring site has on the results of a health study. For this latter purpose, air pollution and temperature monitors are sited at three locations termed green, public, and residential. Then, a decision tree model is used to analyze factors linked with deaths occurring at each monitoring site. The results show that the environmental temperatures before death and the $PM_{2.5}$ concentrations on the day of death are highly linked with the number of deaths regardless of the monitoring location. However, results are most accurate with residential data. The results of this study can be used as base data for a similar analysis and ultimately, as a guide to minimize the health impact of air pollution.

• Structural Monitoring and Maintenance
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• v.10 no.3
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• pp.191-205
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• 2023

In this paper, through operational modal analysis and ambient vibration tests, the dynamic characteristics of a multi-span simply-supported reinforced concrete highway bridge deck was determined and the results were used to assess the quality of construction of the individual spans. Supporting finite element (FE) models were created and analyzed according to the design drawings. After carrying out the dynamic tests and extracting the modal properties of the deck, the quality of construction was relatively assessed by comparing the results obtained from all the tests from the individual spans and the FE results. A comparison of the test results among the different spans showed a maximum difference value of around 9.3 percent between the superstructure's natural frequencies. These minor differences besides the obtained values of modal damping ratios, in which the differences were not more than 5 percent, can be resulted from suitable performance, health, and acceptable construction quality of the bridge.