• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.1101-1107
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• 2010

DVR is widely used in the security monitoring system because it has excellent performance compared with VCR. In this paper, the new DVR interfaces and repeaters enhancing the performance of the existing DVR have been designed and implemented, which enables a large-scaled security monitoring system to be built economically. A repeater in this paper connects 8 monitoring terminals to 2 channels of DVR and a DVR interface manages 16 repeaters to be able to accommodate 128 monitoring terminals. Eventually, the implemented system has a quadruple scalability compared to the existing systems and can reduce the installation cost substantially by using cost-effective UTP cables instead of coaxial cables. And the system could be effectively used in various environments and conditions because various functions such as video transmission, audio communication, emergency call, and RFID card are integrated into the system.

• Structural Monitoring and Maintenance
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• v.2 no.2
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• pp.133-143
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• 2015

Civil engineering infrastructure is aging and requires cost-effective maintenance strategies to enable infrastructure systems operate reliably and sustainably. This paper presents an approach for determining risk-cost balanced repair strategy of corrosion damaged reinforced concrete structures with consideration of uncertainty in structural resistance deterioration. On the basis of analytical models of cover concrete cracking evolution and bond strength degradation due to reinforcement corrosion, the effect of reinforcement corrosion on residual load carrying capacity of corroded reinforced concrete structures is investigated. A stochastic deterioration model based on gamma process is adopted to evaluate the probability of failure of structural bearing capacity over the lifetime. Optimal repair planning and maintenance strategies during the service life are determined by balancing the cost for maintenance and the risk of structural failure. The method proposed in this study is then demonstrated by numerical investigations for a concrete structure subjected to reinforcement corrosion. The obtained results show that the proposed method can provide a risk cost optimised repair schedule during the service life of corroded concrete structures.

• Journal of Korean Society for Quality Management
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• v.43 no.1
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• pp.85-102
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• 2015

Purpose: This study is aimed to develope effective guidelines of R&D institute with regard to general management cost, by analyzing the management characteristics of 14 domestic R&D institutes general management costs. Methods: The bootstrapping method is applied to obtain the average general management cost of 14 R&D institute and the effective R&D institutes are presented by comparing the general management costs of R&D and the rate of inflation. Results: The results show that the average R&D general management cost of 14 R&D institutes is 3.32% and, in general, it turns out that the R&D general management costs do not reflect the inflation rate after a comparative analysis of the variation of the R&D general management costs. In addition, the results of cost-effective analysis show that only 5 R&D institutes are efficient in R&D activities. Conclusion: Applying a uniform standard of R&D general management costs although their management characteristics are different, can cause the impediment to the independence and transparency of R&D institutes. Therefore it is recommended a strict implementation with respect to the monitoring system of each R&D institute and the budget policy methods which are reflected management characteristics.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.865-868
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• 2008

Remote Sur-veillance network system for water contamination is developed using sensor network. The wireless sensor network is one of effective solutions for monitoring water contamination on wide area such s river. Existing sur-veillance system for water contamination has the disadvantage in installation cost, complexity of adding a new node replacing a defective node. The proposed system has cost effective solutions compared with the existing system.

• Journal of Microbiology and Biotechnology
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• v.19 no.1
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• pp.93-98
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• 2009

The thermophilic aerobic digestion (TAD) process is recognized as an effective method for rapid waste activated sludge (WAS) degradation and the deactivation of pathogenic microorganisms. Yet, high energy costs due to heating and aeration have limited the commercialization of economical TAD processes. Previous research on autothermal thermophilic aerobic digestion (ATAD) has already reduced the heating cost. However, only a few studies have focused on reducing the aeration cost. Therefore, this study applied a two-step aeration control strategy to a fill-and-draw mode semicontinuous TAD process. The NADH-dependent fluorescence was monitored throughout the TAD experiment, and the aeration rate shifted according to the fluorescence intensity. As a result, the simple two-step aeration control operation achieved a 20.3% reduction in the total aeration, while maintaining an effective and stable operation. It is also expected that more savings can be achieved with a further reduction of the lower aeration rate or multisegmentation of the aeration rate.

• Safety and Health at Work
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• v.10 no.4
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• pp.452-460
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• 2019

Background: Monitoring and control of PM_2.5 are being recognized as key to address health issues attributed to PM_2.5. Availability of low-cost PM_2.5 sensors made it possible to introduce a number of portable PM_2.5 monitors based on light scattering to the consumer market at an affordable price. Accuracy of light scatteringe-based PM_2.5 monitors significantly depends on the method of calibration. Static calibration curve is used as the most popular calibration method for low-cost PM_2.5 sensors particularly because of ease of application. Drawback in this approach is, however, the lack of accuracy. Methods: This study discussed the calibration of a low-cost PM_2.5-monitoring device (PMD) to improve the accuracy and reliability for practical use. The proposed method is based on construction of the PM_2.5 sensor network using Message Queuing Telemetry Transport (MQTT) protocol and web query of reference measurement data available at government-authorized PM monitoring station (GAMS) in the republic of Korea. Four machine learning (ML) algorithms such as support vector machine, k-nearest neighbors, random forest, and extreme gradient boosting were used as regression models to calibrate the PMD measurements of PM_2.5. Performance of each ML algorithm was evaluated using stratified K-fold cross-validation, and a linear regression model was used as a reference. Results: Based on the performance of ML algorithms used, regression of the output of the PMD to PM_2.5 concentrations data available from the GAMS through web query was effective. The extreme gradient boosting algorithm showed the best performance with a mean coefficient of determination (R²) of 0.78 and standard error of 5.0 ㎍/㎥, corresponding to 8% increase in R² and 12% decrease in root mean square error in comparison with the linear regression model. Minimum 100 hours of calibration period was found required to calibrate the PMD to its full capacity. Calibration method proposed poses a limitation on the location of the PMD being in the vicinity of the GAMS. As the number of the PMD participating in the sensor network increases, however, calibrated PMDs can be used as reference devices to nearby PMDs that require calibration, forming a calibration chain through MQTT protocol. Conclusions: Calibration of a low-cost PMD, which is based on construction of PM_2.5 sensor network using MQTT protocol and web query of reference measurement data available at a GAMS, significantly improves the accuracy and reliability of a PMD, thereby making practical use of the low-cost PMD possible.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5B
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• pp.824-832
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• 2010

In construction structure management, the effects of investigation by the professional manager is dependent on the cost, the inspection periods and methods. Therefore, effective and automated maintenance system for the target structure is required. Although some bridge monitoring systems are operating using wire based networks, the performance is not good enough to show sufficient ability as integrated bridge management system. In this paper, we design and implement an integrated bridge management system based on sensor networks. Two expert modules for bridge management and the integrated system management are provided. Moreover, web-based monitoring system is also designed for users at anywhere. The results show that the system is effective and readily available.

• Nuclear Engineering and Technology
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• v.49 no.7
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• pp.1489-1494
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• 2017

The use of a room-temperature gamma spectrometer is an issue in environmental radiation monitoring. To monitor radionuclides released around a nuclear power plant, suitable instruments giving fast and reliable information are required. High-pressure xenon (HPXe) chambers have range of resolution and efficiency equivalent to those of other medium resolution detectors such as those using NaI(Tl), CdZnTe, and $LaBr_3:Ce$. An HPXe chamber could be a cost-effective alternative, assuming temperature stability and reliability. The CEA LIST actively studied and developed HPXe-based technology applied for environmental monitoring. Xenon purification and conditioning was performed. The design of a 4-L HPXe detector was performed to minimize the detector capacitance and the required power supply. Simulations were done with the MCNPX2.7 particle transport code to estimate the intrinsic efficiency of the HPXe detector. A behavioral study dealing with ballistic deficits and electronic noise will be utilized to provide perspective for further analysis.

• Korean Journal of Biological Psychiatry
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• v.5 no.1
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• pp.56-65
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• 1998

Clinicians can use therapeutic drug monitoring(TDM) to optimise dosage decisions with psychotropic drugs, in order to maximize efficacy and prevent toxicity, especially when individuals are nonresponsive to treatment or vulnerable to adverse reactions with standard doses because age, disease states or drug interactions. Currently, therapeutic drug concentrations have been established for the TCA and lithium. There is also evidence for the usefulness of TDM with carbamazepine, valproic acid and some antipsychotic drugs. However for most psychotropic drugs this approach remains experimental. TDM-assisted psychiatric treatment is potentially useful and cost effective, particularly when applied by psychiatrists who are knowledgeable of pharmacokinetics and pharmacodynamics.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.747-752
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• 2008

Fiber-guided sensor system using a generator and a receiver can detect the amplitude of load or pressure. However, this type of sensor can show some difficulties in detecting the location of damages and pressure loadings. To overcome this weakness of this type, the ultrasonic active fiber sensor, which has an integrated ultrasonic generator and sensing part, was developed in this study. By using this sensor system, the location of mechanical loads can be exactly detected. Moreover, the ultrasonic active fiber sensor is more cost-effective than an ultrasonic fiber sensor using two piezoelectric transducers which are used as a generator and a receiver, respectively. Two applications of the ultrasonic active fiber sensor are demonstrated: cure monitoring of lead and measurement of liquid level. Present results showed that the active fiber sensor can be applied for various environmental sensing.