• Clean Technology
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• v.15 no.2
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• pp.130-136
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• 2009

Commercial catalyst (Cu-Zn/$Al_2O_3$, Johnson Matthey Co., 83-3 Catalyst) was applied to the hydrogen production by steam reforming of methanol in the micro-channel reactor (MCR). The steam reforming of methanol was tested over Cu-Zn catalyst at temperatures in the range of 200 and 300$^{\circ}C$, the catalyst size of 0.05${\sim}$2.2 mm, the space velocity of 3,000${\sim}$10,000 $hr^{-1}$ in a fixed bed continuous flow reactor. The conversion of methanol and the yield $H_2$ preferred high temperatures and low space velocities, and had optimal results with the particle size of 0.35 mm. Based on the results from experiments with fixed bed reactor, two types of MCR, boat bed and stacked bed MCRs, were studied. The stacked bed type MCR showed better methanol conversion compared with the boat type one.

• Journal of the Society of Disaster Information
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• v.14 no.3
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• pp.262-270
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• 2018

Purpose: This paper investigates and analyzes the loss and damage ratio of maintenance monitoring sensor in metropolitan and high speed railroad tunnel in Korea and abroad. Method: After 5~6 years from the installation, the maintenance monitoring sensor on metropolitan transit tunnels showed the loss and damage ratio from 14.2% to 14.8% in Seoul metro line no. 5, 6, 7, 9, and 13.9% in UK channel tunnel. Based on the result, 15% is thought to be a proper set for the elapsed years, which is 5 years from the installation. Results: The maintenance monitoring sensor on high speed railroad tunnels showed the loss and damage ratio of 60.9% in Ho-Nam high speed railroad on 1 stage after 3 ~ 5 years from the installation, which was approximately 4 times as high as that of Seoul metro line no. 5, 6, 7, 9. Conclusion: Kyung-Bu high speed railroad on 2 stage, after 8~10 years from the installation, showed the loss and damage ratio of 66.8%. Based on the result, it can be inferred that the loss and damage ratio increases drastically after 5~10 years from the installation. Therefore, it is necessary to study on the loss and damage ratio of long term elapsed years, especially more than 10 years from the installation.

• Nuclear Engineering and Technology
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• v.39 no.2
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• pp.133-142
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• 2007

The Electric Power Research Institute (EPRI) demonstrated a method for monitoring the performance of instrument channels in Topical Report (TR) 104965, 'On-Line Monitoring of Instrument Channel Performance.' This paper presents the results of several models originally developed by EPRI to monitor three nuclear plant sensor sets: Pressurizer Level, Reactor Protection System (RPS) Loop A, and Reactor Coolant System (RCS) Loop A Steam Generator (SG) Level. The sensor sets investigated include one redundant sensor model and two non-redundant sensor models. Each model employs an Auto-Associative Kernel Regression (AAKR) model architecture to predict correct sensor behavior. Performance of each of the developed models is evaluated using four metrics: accuracy, auto-sensitivity, cross-sensitivity, and newly developed Error Uncertainty Limit Monitoring (EULM) detectability. The uncertainty estimate for each model is also calculated through two methods: analytic formulas and Monte Carlo estimation. The uncertainty estimates are verified by calculating confidence interval coverages to assure that 95% of the measured data fall within the confidence intervals. The model performance evaluation identified the Pressurizer Level model as acceptable for on-line monitoring (OLM) implementation. The other two models, RPS Loop A and RCS Loop A SG Level, highlight two common problems that occur in model development and evaluation, namely faulty data and poor signal selection

• Journal of Industrial Technology
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• v.28 no.B
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• pp.39-45
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• 2008

Temperature variation according to space and time on the inner parts of engineering constructions(e.g.: dam, slope) can be a basic information for diagnosing their safety problem. In general, as constructions become superannuated, structural deformation(e.g.: cracks, defects) could be occurred by various factors. Seepage or leakage of water through these cracks or defects in old dams will directly cause temperature anomaly. Groundwater level also can be easily observed by abrupt change of temperature on the level. This study shows that the position of seepage or leakage in dam body can be detected by multi-channel temperature monitoring using thermal line sensor. For this, diverse temperature monitoring experiments for a leakage physical model were performed in the laboratory. In field application of an old earth fill dam, temperature variations for water depth and for inner parts of boreholes located at downstream slope were measured. Temperature monitoring results for a long time at the bottom of downstream slope of the dam showed the possibility that temperature monitoring can provide the synthetic information about flowing path and quantity of seepage of leakage in dam body.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.9
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• pp.81-87
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• 2009

In this paper, remote monitoring system for wind turbine site is developed. This system is a hierarchical reliable monitoring system connected by wireless communication channels between monitoring host computer and modular slave measuring subsystems. The design of this systems; the slave measuring subsystems is placed in meteorological tower and wind turbine, and the supervisory host computer is in the safety zone. The slave measuring subsystems signals are from a meteorological tower, wind turbine generator and tower. For monitoring and command function, the supervisory computer is implemented with a PC using graphic user interface. This system can be transferred the information among host computer and remote computers through the Ethernet. Consequently we can get reliability but economic system. The system has the concept of universality and modularity, so it is simple and easy to implement in wind turbine test sites.

• Journal of Satellite, Information and Communications
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• v.8 no.3
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• pp.15-19
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• 2013

Lithium-ion batteries have been used for high density energy storage system due to the features such as low self-discharge rate. And the unit cell battery with the voltage less than 4V is recommended to use the series connections for a high voltage charger. When batteries are charged or discharged with series connection, there may be an explosion or degradation of unit cell battery owing to undistributed internal resistance of cell battery. therefore, the voltages of unit cell batteries should be monitored to prevent an overcharging and a deep discharging. This paper introduces the implementation of CVM (Cell Voltage Monitoring) system that can transmit the 12 channel's information including voltages and temperatures with the 12-bits resolutions and the transmission speed of 192 kbps.

• Smart Structures and Systems
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• v.29 no.1
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• pp.181-193
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• 2022

Data-driven structural health monitoring (SHM) of civil infrastructure can be used to continuously assess the state of a structure, allowing preemptive safety measures to be carried out. Long-term monitoring of large-scale civil infrastructure often involves data-collection using a network of numerous sensors of various types. Malfunctioning sensors in the network are common, which can disrupt the condition assessment and even lead to false-negative indications of damage. The overwhelming size of the data collected renders manual approaches to ensure data quality intractable. The task of detecting and classifying an anomaly in the raw data is non-trivial. We propose an approach to automate this task, improving upon the previously developed technique of image-based pre-processing on one-dimensional (1D) data by enriching the features of the neural network input data with multiple channels. In particular, feature engineering is employed to convert the measured time histories into a 3-channel image comprised of (i) the time history, (ii) the spectrogram, and (iii) the probability density function representation of the signal. To demonstrate this approach, a CNN model is designed and trained on a dataset consisting of acceleration records of sensors installed on a long-span bridge, with the goal of fault detection and classification. The effect of imbalance in anomaly patterns observed is studied to better account for unseen test cases. The proposed framework achieves high overall accuracy and recall even when tested on an unseen dataset that is much larger than the samples used for training, offering a viable solution for implementation on full-scale structures where limited labeled-training data is available.

• KSBB Journal
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• v.13 no.1
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• pp.71-76
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• 1998

Tissue biosensor for mearsuring sodium channel blockers, such tetrodotoxin(TTX), saxitoxin (STX) and paralytic shellfish poisoning(PSP) consisted of frog bladder membrane, and $Na^{+}$ electrode. The proposed biosensor was applied to determine Chinese drug and dry or wet Porphyra yezonesis $Na^{+}$ channel blockers below the detection limit of the standard mouse bio-assay while the observed detection limit didn't cause human poisoning. The proposed biosensor system may be used for future $Na^{+}$ channel blockers monitoring within the marine environment.

• Journal of Environmental Impact Assessment
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• v.18 no.4
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• pp.219-227
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• 2009

Because of urban development and changed land cover types, It is very important to acquire pixel unit of land surface temperature(LST) information when the heat island effect(HIE) of regional area are investigated. The brightness temperature observed by satellite is very useful for assessing the pixel unit of LST distributions for the analysis of thermal environment problems of urban areas. Also, satellite land cover data are very useful to our understanding of surface conditions of study areas. In this study, brightness temperature information of Landsat TM thermal channel was analyzed and compared with land cover information of Jeon-ju city. The atmospheric correction of TM thermal channel carried out to explain for compared LST long term monitoring errors. However, simple estimation and evaluation methods to find a physical relationship between LST from satellite images and in-situ data are compared with reference channel emissivity.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.221-224
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• 2004

최근 무선 랜의 상용화에 따른 다양한 어플리케이션들이 제공되고 있다. 이 중 대용량 멀티미디어 트래픽을 사용한 다양한 서비스가 제공되고 있는데, 이들에 대한 QoS 보장을 위한 다양한 기법들이 세안되고 있다. 기존의 802.11에서는 CSDP 스케줄러를 이용하여 각각의 MH로 보내지는 데이터에 대한 QoS를 보장하기 위해 노력하였고, WG(Working Group) e가 만들어지면서 보다 상세하게 데이터 트래픽에 대한 QoS를 더 연구하게 되었다. 본 논문에서 제안하고자 하는 스케줄러는 IEEE 802.11에 CSDP (Channel State Dependent Packet) 스케줄러의 LSM(Link State Monitoring)의 개념과 IEEE 802.11e에서 제안하고 있는 EDCA (Enhanced Distributed Channel Access)방식과 HCCA (HCF Controlled Channel Access) 방식이 결합되어 있는 스케줄러에 실제 스케줄링이 이루어지는 PHY Queue에 가기 전 대기하는 Queue에 가상 큐를 적용하여 트레픽 특성을 고려하고, bad가 발생하는 링크로 가는 트래픽에 대해서는 임시 큐에 저장한 후에 링크가 good 상태가 되면 전송함으로써 보다 높은 QoS를 제공하며, 전체 시스템의 효율을 향상시키는 스케줄러를 제안하고자 한다.