• Proceedings of the KIEE Conference
• /
• 2006.10c
• /
• pp.588-590
• /
• 2006

Recently, many on-line approaches to instrument channel surveillance (drift monitoring and fault detection) have been reported worldwide. On-line monitoring (OLM) method evaluates instrument channel performance by assessing its consistency with other plant indications through parametric or non-parametric models. The heart of an OLM system is the model giving an estimate of the true process parameter value against individual measurements. This model gives process parameter estimate calculated as a function of other plant measurements which can be used to identify small sensor drifts that would require the sensor to be manually calibrated or replaced. This paper describes an improvement of auto-associative kernel regression by introducing a correlation coefficient weighting on kernel distances. The prediction performance of the developed method is compared with conventional auto-associative kernel regression.

• Proceedings of the KIEE Conference
• /
• 2001.11c
• /
• pp.268-271
• /
• 2001

This paper presents observer-based on-line overload monitoring scheme for a PMSM(Permanent Magnet Synchronous Motor) drive system. Proposed scheme is to monitor overload status of motor drive system at remote place. The drive system is previously installed on main system and has no communication function. Proposed scheme consists of intelligent sensing head and monitoring part. Intelligent sensing head acquire motor 3-Phase currents and transmit data to monitoring part over serial communication interface. Monitoring part estimates motor speed using state observer. By comparing estimated speed with reference speed, we can detect motor fault. In this scheme observed information must coded and transmitted over a digital communication channel with finite capacity. We consider communication constraint as time delay and we design discrete-time observer. The proposed scheme is tested on the actual drive system.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.8
• /
• pp.1779-1782
• /
• 2009

The developed system is captured by RS-232 telecommunication receiving data (temperature and humidity of each incubator) through radio frequency sensor network system and is made by monitoring system for one person collecting each channel data. This monitoring system is capable of monitoring not only PDA through TCP/IP telecommunication but also personal computer. This system is actively application on telecommunication function of LabVIEW and PDA module and is considerably saved in processing time than using in other tools.

• Journal of Biomedical Engineering Research
• /
• v.29 no.4
• /
• pp.295-301
• /
• 2008

A wireless 3 channel ECG monitoring system was developed so that it could monitor the health and movement state during subject's daily life. The developed system consists of a wireless biomedical signal acquisition device, a personal healthcare server, and a remote medical server. Three experiments were performed to evaluate the accuracy, reliability and operability, applicability during daily life of the developed device. First, ECG signals were measured using the developed device and commercial reference device during sitting and marking time and compared to verify the accuracy of R-R intervals. Second, the reliable data transmission to remote server was verified on two types of simulated emergency event using patient simulator. Third, during five types of motion in daily life, the accuracy of data transmission to remote server using CDMA network was verified on two types of event occurring. By acquiring and comparing subject's biomedical signal and motion signal, the accuracy, reliability and operability, applicability during daily life of the developed device were verified. In addition, PDA-phone based wireless system enabled subject to be monitored without any constraints. Therefore, the developed system is expected to be applicable for monitoring the aged and chronic diseased people and giving first-aid in emergency.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.05a
• /
• pp.165-166
• /
• 2010

• Proceedings of the Korean Nuclear Society Conference
• /
• 1998.10a
• /
• pp.121-121
• /
• 1998

• Smart Structures and Systems
• /
• v.11 no.3
• /
• pp.261-282
• /
• 2013

Structural health monitoring (SHM) is an application area of Wireless Sensor Networks (WSNs) which usually needs high data communication rate to transfer a large amount of monitoring data. Traditional sink node can only process data from one communication channel at the same time because of the single radio chip structure. The sink node constitutes a bottleneck for constructing a high data rate SHM application giving rise to a long data transfer time. Multi-channel communication has been proved to be an efficient method to improve the data throughput by enabling parallel transmissions among different frequency channels. This paper proposes an 8-radio integrated sink node design method based on Field Programmable Gate Array (FPGA) and the time synchronization mechanism for the multi-channel network based on the proposed sink node. Three experiments have been performed to evaluate the data transfer ability of the developed multi-radio sink node and the performance of the time synchronization mechanism. A high data throughput of 1020Kbps of the developed sink node has been proved by experiments using IEEE.805.15.4.

• Journal of Environmental Science International
• /
• v.12 no.8
• /
• pp.891-896
• /
• 2003

The objectives of this study wre to investigate the effects of two synthetic pyrethroids, bifenthrin(BF) and permethrin(PM), in runoff and to evaluate the effects of suspended solids (SS) in the transport of pyrethroid along the drainage channel. Monitoring of BF and PM was conducted with the runoffs as well as in sediments existing along the drainage channel at a nursery site located in southern California, USA. This study also suggests Best Management Practices (BMPs) to alleviage the pollution caused by heavy usage of pyrethroid insecticides at nursery sites. Due to a high affinity to solid particles of pyrethroid insecticides, the concentrations of BF and PM were proportional to the SS contents along the drainage channel. This study suggests that alleviation of pyrethroids existing in runoffs could be controlled by the removal of suspended solids in runoffs and potential implications of current drainage channels for mitigation of pesticides associated with runoffs.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.2
• /
• pp.40-49
• /
• 1996

In this paper, we studied channel assignment and handover schemes for the indoor microcell systems. For efficient frequency spectrum reuse we proposed the high quality reassignment (HQR) scheme. Proposed HQR scheme tries to keep the reuse distances small by monitoring C/I of channels being used. To assign a channel for a new or handove call, the scheme checks C/I of all available channels. Then HQR assigns the channel that has C/I near the threshold value, A_TH. The scheme also checks C/I of ongoing calls and continuously reassigns a new channel when needed. It attempts handover not only when C/I gets below a handover threshold value, HO_TH, but also when C/I becomes above a high quality reassignment threshold, H_TH. The performance of the proposed HQR scheme was analyzed by a computer simulation configuraed. The performance of the scheme was also analyzed for various threshold values selected and the results are presented in this paper. The results show that HQR scheme perfomrs better than the scheme adopted for DECT.

• ETRI Journal
• /
• v.29 no.5
• /
• pp.607-613
• /
• 2007

Most signal-to-noise ratio (SNR) estimation techniques in digital communication channels derive the SNR estimates solely from samples of the received signal after the matched filter. They are based on symbol SNR and assume perfect synchronization and intersymbol interference (ISI)-free symbols. In severe channel distortion where ISI is significant, the performance of these estimators badly deteriorates. We propose an SNR estimator which can operate on data samples collected at the front-end of a receiver or at the input to the decision device. This will relax the restrictions over channel distortions and help extend the application of SNR estimators beyond system monitoring. The proposed estimator uses the characteristics of the second order moments of the additive white Gaussian noise digital communication channel and a linear predictor based on the modified-covariance algorithm in estimating the SNR value. The performance of the proposed technique is investigated and compared with other in-service SNR estimators in digital communication channels. The simulated performance is also compared to the Cram$\acute{e}$r-Rao bound as derived at the input of the decision circuit.