• Journal of Environmental Health Sciences
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• v.32 no.3
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• pp.207-214
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• 2006

This study was designed to assess the level of nitrogen dioxide from several microenvironments including inside the home, outdoors near the home, inside the school, outdoors near the school, and on the road for 42 primary schoolchildren during the month of December 2002 in Seoul, Korea. The average personal, indoor, outdoor $NO_2$ levels, and indoor/outdoor ratio were 45.08 ppb, 27.89 ppb, 30.96 ppb, and 0.89, respectively. The indoor $NO_2$ concentrations were significantly associated with the presence of a smoker with a gas stove. The estimated personal $NO_2$ exposure using time-weighted average equation of $34.64{\pm}5.29$ ppb was significantly lower than the measured personal exposure of $45.08{\pm}5.50$ ppb. Our results indicate that indoor $NO_2$ levels were associated with the presence of a smoker and a gas stove. Moreover, personal $NO_2$ exposure with a gas stove in the house was significantly higher than those without a gas stove.

• The KIPS Transactions:PartC
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• v.13C no.5 s.108
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• pp.559-566
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• 2006

Virus throttling technique, one of many early worm detection techniques, detects the Internet worm propagation by limiting the connect requests within a certain ratio. The typical virus throttling detects worm occurrence by monitoring the length of delay queue with the fixed period of rate limiter. In this paper, we propose an algorithm that controls the period of rate limiter autonomically by utilizing the weighted average delay queue length and suggest various period determination policies that use the weighted average delay queue length as an input parameter. Through deep experiments, it is verified that the proposed technique is able to lessen inconvenience of users by reducing the connection delay time with haying just little effect on worm detection time.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.4
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• pp.959-966
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• 2010

Quantitative ultrasound analysis provides fundamental information of various ultrasound parameters using spectral information of the short-gated radiofrequency(RF) data. Therefore, accurate extraction of spectral information from backscattered RF signal is crucial for further analysis of medical ultrasound parameters. In this paper, we propose two techniques for calculating a more accurate power spectrum which are based on the phase-compensation using the normalized cross-correlation to minimize estimation errors due to phase variations, and the weighted averaging technique to maximize the signal-to-noise ratio(SNR). The simulation results demonstrate that the proposed method estimates better results with 10% smaller estimation variances compared to the conventional methods.

• Journal of Sensor Science and Technology
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• v.25 no.6
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• pp.418-422
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• 2016

A filtering algorithm based on the decentralized moving average Kalman filter with uncertainties is proposed in this paper. The proposed filtering algorithm presented combines the Kalman filter with the moving average strategy. A decentralized fusion algorithm with the weighted sum structure is applied to the local moving average Kalman filters (LMAKFs) of different window lengths. The proposed algorithm has a parallel structure and allows parallel processing of observations. Hence, it is more reliable than the centralized algorithm when some sensors become faulty. Moreover, the choice of the moving average strategy makes the proposed algorithm robust against linear discrete-time dynamic model uncertainties. The derivation of the error cross-covariances between the LMAKFs is the key idea of studied. The application of the proposed decentralized fusion filter to dynamic systems within a multisensor environment demonstrates its high accuracy and computational efficiency.

• Journal of Environmental Health Sciences
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• v.27 no.1
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• pp.20-26
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• 2001

personal nitrogen dioxide(NO$_2$) exposures for 31 professional drivers were measured using passive sampler and time activity diary in Asan and Chunan area, and were estimated using time-weighted average model. Mean concentrations of driver’s indoor and outdoor were 24.7$\pm$10.7 ppb and 23.3$\pm$8.3 ppb, respectively with indoor/outdoor of 1.1. Mean personal NO$_2$ exposure was 30.3$\pm$9.7 ppb. Personal NO$_2$ exposures were strongly correlated with indoor car NO$_2$ levels ($R^2$=0.80) rather than residential indoor NO$_2$ level ($R^2$=0.55). and outdoor NO$_2$ level ($R^2$=0.50). The driver’s NO$_2$ exposure using LP-gas with 24.4$\pm$8.0 ppb were statistically different from those using diesel with 36.3$\pm$14.1 ppb(p<0.01). The effect of driver’s smoking for personal NO$_2$ exposure was not found. It was considered that the main NO$_2$in driver is transportation. Since drivers mostly spent their times in indoor and inside car, time-weighted average model could be used to estimated personal NO$_2$ exposure using time activity diary, Though we did not measure all microenvironments, the estimated personal NO$_2$ exposures with 26.9$\pm$10.2 ppb were statistically correlated with measured personal NO $_2$ exposures30.3$\pm$9.7 ppb ($R^2$=0.89). The mean and standard deviation of personal NO$_2$ exposure using Mote-Carlo simulation were 26.6$\pm$7.2 ppb.

• Journal of Magnetics
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• v.17 no.2
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• pp.158-162
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• 2012

Although 3.0T magnetic resonance imaging (MRI) has the advantages of a higher signal to noise ratio (SNR) and contrast than 1.5T MRI, there are limitations on the contrast between white and grey matter because of the long T1 recovery time when T1 images are obtained using the Spin Echo Technique. To overcome this, T1 weighted images are obtained occasionally using the inversion recovery (IR) technique, which employs a relatively long TR. The aim of this study was to determine the optimal TI in a brain examination when a T1 weighted image is obtained using the IR technique. Eight participants (male: 7, female: 1, average age: $34{\pm}14.11$) with a normal diagnosis were targeted from February 18, 2012 to February 27, 2012, and the contrast between white and grey matter as well as the contrast to noise ratio (CNRs) in each participant were measured. The CNRs of white matter and grey matter were highest at TI = 600, 650, 750, 900, 1050 and 1100 ms when the TR was 1100, 1400, 1700, 2000, 2300 and 2600 ms, respectively. Therefore, as the TIs were $44.425{\pm}0.877%$ of the TRs in the TR range of 1400-2300 ms, the optimal T1 weighted images that describe the contrast between white and grey matter can be obtained if the TIs are compensated for with $44.425{\pm}0.877%$ of the TRs in the time of setting TIs.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.747-749
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• 2000

A new scheduling algorithm called the Adaptive Weighted Round Robin with Delay Tolerance (AWRR/DT) is presented. The proposed scheme can reduce the average delay of non-real-time (NRT) class while maintaining the QoS of real-time (RT) classes. Our scheme can also reflect the traffic fluctuation of networks with a small processing burden.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.196-204
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• 2013

In this paper, a scheduling algorithm is proposed for military satellite networks to improve QoS(Quality of Service) based on WDRR(Weighted Deficit Round Robin) method. When the packet size that has been queued to be larger, the proposed scheme DWDRR(Dynamic WDRR) method give appropriate additional quantum using EWMA(Exponentially Weighted Moving Average). To demonstrate an usefulness of proposed algorithm using OPNET modeler that built the simulation environment, reliability and real-time availability of the proposed algorithm is analyzed. The simulation results show an availability of proposed scheme in terms of reduce queuing delay and packet drop rate compared and analyzed the existing algorithms WRR(Weighted Round Robin), DRR(Deficit Round Robin) and WDRR with DWDRR.

• Journal of Sensor Science and Technology
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• v.28 no.2
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• pp.88-93
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• 2019

This paper is concerned with distributed fusion moving average prediction for continuous-time linear stochastic systems with multiple sensors. A distributed fusion with the weighted sum structure is applied to the optimal local moving average predictors. The distributed fusion prediction algorithm represents the optimal linear fusion by weighting matrices under the minimum mean square criterion. The derivation of equations for error cross-covariances between the local predictors is the key of this paper. Example demonstrates effectiveness of the distributed fusion moving average predictor.

• International Journal of Control, Automation, and Systems
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• v.5 no.5
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• pp.492-500
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• 2007

This paper focuses on the problem of guaranteed cost control for a class of uncertain linear delay systems with actuator failures. When actuators suffer "serious failure" the never failed actuators can not stabilize the system, based on switching strategy of average dwell time method, under the condition that activation time ratio between the system without actuator failure and the system with actuator failures is not less than a specified constant, a sufficient condition for exponential stability and weighted guaranteed cost performance are developed in terms of linear matrix inequalities (LMIs). Finally, as an example, a river pollution control problem illustrates the effectiveness of the proposed approach.