• International Journal of Highway Engineering
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• v.16 no.5
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• pp.99-108
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• 2014

PURPOSES : The travel times of expressway buses have been estimated using the travel time data between entrance tollgates and exit tollgates, which are produced by the Toll Collections System (TCS). However, the travel time data from TCS has a few critical problems. For example, the travel time data include the travel times of trucks as well as those of buses. Therefore, the travel time estimation of expressway buses using TCS data may be implicitly and explicitly incorrect. The goal of this study is to improve the accuracy of the expressway bus travel time estimation using DSRC-based travel time by identifying the appropriate analysis period of input data. METHODS : All expressway buses are equipped with the Hi-Pass transponders so that the travel times of only expressway buses can be extracted now using DSRC. Thus, this study analyzed the operational characteristics as well as travel time patterns of the expressway buses operating between Seoul and Dajeon. And then, this study determined the most appropriate analysis period of input data for the expressway bus travel time estimation model in order to improve the accuracy of the model. RESULTS : As a result of feasibility analysis according to the analysis period, overall MAPE values were found to be similar. However, the MAPE values of the cases using similar volume patterns outperformed other cases. CONCLUSIONS : The best input period was that of the case which uses the travel time pattern of the days whose total expressway traffic volumes are similar to that of one day before the day during which the travel times of expressway buses must be estimated.

• Journal of Biomedical Engineering Research
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• v.16 no.2
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• pp.223-230
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• 1995

This study investigates a combined mathematical model for the quantitative estimation of regional myocardial blood flow in experimental canine coronary artery occlusion and in patients with ischemic myocardial diseases using Rb-82 dynamic myocardial positron emission tomography. The coronary thrombosis was induced using the new catheter technique by narrowing the lumen of coronary vessel gradually, which finally led to partial obstruction of coronary artery. Thirty four Rb-82 dynamic myocardial PET scans were performed sequentially for each experiment using our 5, 10 and 20 second acquisition protocol, respectively, and six to seven regions of interest were drawn on each transaxial slices, one on left ventricular chamber for input function and the others on normal and decreased perfusion myocardial segments for the flow estimation in those regions. Two compartment model and graphical analysis method have been applied to the measured sets of regional PET data, and the rate constants of influx to myocardial tissue were calculated for regional myocardial flow estimates with the two parameter fits of raw data by the Levenberg-Marquardt method. The results showed that, (I) two compartment model suggested by Kety-Schmidt, with proper modification of the measured data and volume of distribution, could be used for the simple estimation of regional myocardial blood flow, (2) the calculated regional myocardial blood flow estimates were dependent on the selection of input function, which reflected partial volume effect and left ventricular wall motion in previously used graphical analysis, and (3) mathematically fitted input and tissue time activity curves were more suitable than the direct application of the measured data in terms of convergence.

• Journal of KIISE:Databases
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• v.33 no.6
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• pp.590-599
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• 2006

Disordered streams cause two issues in processing sliding windows: i) how to place input tuples into a buffer in an increasing order efficiently and ii) how to determine a time point to process the windows from input tuples in the buffer. To address these issues, we propose a structure and method of operators for processing sliding windows. We first present a structure of the operators using an index to handle input tuples efficiently. Then, we propose a method to determine the time point to process the windows, which is called a mean-based estimation. In the proposed method, users can describe parameters required for estimation in a query specification, which provides a way for users to control the properties of query results such as the accuracy or the response time according to application requirements. Our experimental results show that the mean-based estimation provides better adaptivity and stability than the one used in the existing method.

• Environmental and Resource Economics Review
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• v.3 no.2
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• pp.289-307
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• 1994

• Proceedings of the Korea Water Resources Association Conference
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• 1993.07a
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• pp.393-400
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• 1993

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.309-310
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• 2016

Sealed flooded lead acid batteries are becoming popular in the industry because of their low cost as compared to their counterparts. State of Charge (SOC) estimation has always been an important factor in battery management systems. For the accurate SOC estimation, open circuit voltage (OCV) hysteresis should be modelled accurately. The hysteresis phenomenon of the sealed flooded lead acid battery is discussed in detail and its ultimate modeling is proposed based on the conventional parallelogram method. The SOC estimation is performed by using Unscented Kalman Filter (UKF) while the parameters of the battery are estimated using Auto Regressive with external input (ARX) method. The validity of the proposed method is verified by the experimental results. The SOC estimation error by the proposed method is less than 3 % all wing the 125hr test.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.7
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• pp.37-42
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• 2008

In this paper, a real-time multiview video coding system using fast disparity estimation is proposed. In the multiview encoder, adaptive disparity-motion estimation (DME) for an effective 3-dimensional (3D) processing are proposed. That is, by adaptively predicting the mutual correlation between stereo images in the key-frame using the proposed algorithm, the bandwidth of stereo input images can be compressed to the level of a conventional 2D image and a predicted image also can be effectively reconstructed using a reference image and adaptive disparity vectors. Also, in multiview decoder, intermediate view reconstruction (IVR) using adaptive disparity search algorithm (DSA) for real-time multiview video processing is proposed. The proposed IVR can reduce a processing time of disparity estimation by selecting adaptively disparity search range. Accordingly, the proposed multiview video coding system is able to increase the efficiency of the coding rate and improve the resolution.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.10
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• pp.895-900
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• 2016

Remaining useful life (RUL) estimation of the Li-ion battery has gained great interest because it is necessary for quality assurance, operation planning, and determination of the exchange period. This paper presents the RUL estimation of an Li-ion battery for an energy storage system using exponential function for the degradation model and Markov Chain Monte Carlo (MCMC) approach for parameter estimation. The MCMC approach is dependent upon information such as model initial parameters and input setting parameters which highly affect the estimation result. To overcome this difficulty, this paper offers a guideline for model initial parameters based on the regression result, and MCMC input parameters derived by comparisons with a thorough search of theoretical results.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.2
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• pp.19-26
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• 2011

SATEEC ArcView GIS system was developed using the Universal Soil Loss Equation (USLE) and sediment delivery ratio (SDR) modules. In addition, time-variant R and C modules and $R_5$ module were developed and integrated into the SATEEC system in recent years. The SATEEC ArcView GIS 2.1 system is a simple-to-use system which can estimate soil erosion and sediment yield spatially and temporarily using only USLE input data, DEM, and daily rainfall dataset. In this study, the SATEEC 2.1 system was used to evaluate the effects of USLE LS input data considering slope length segmentation on soil erosion and sediment yield estimation. Use of USLE LS with slope length segmentation due to roads in the watershed, soil erosion estimation decreased by 24.70 %. However, the estimated sediment yield using SATEEC GA-SDR matched measured sediment values in both scenarios (EI values of 0.650 and EI 0.651 w/o and w/flow segmentation). This is because the SATEEC GA-SDR module estimates lower SDR in case of greater soil erosion estimation (without flow length segmentation) and greater SDR in case of lower soil erosion estimation (with flow length segmentation). This indicates that the SATEEC soil erosion need to be estimated with care for accurate estimation of SDR at a watershed scale and for accurate evaluation of BMPs in the watershed.

• Journal of Broadcast Engineering
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• v.24 no.5
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• pp.879-891
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• 2019

This paper provides performance evaluations of various channel estimation schemes for Advanced Television Systems Committee (ATSC) 3.0 multiple-input multiple-output (MIMO) system under a fixed reception environment. ATSC 3.0 MIMO system can obtain high spectral efficiency and improved reception performance compared to conventional terrestrial broadcasting systems. The ATSC 3.0 MIMO defines Walsh-Hadamard and null pilot encoding algorithms and the amplitude and phase of MIMO pilots are different from those of single-input single-output pilots. At the receiver, linear and discrete Fourier transform (DFT)-based interpolations can be used for the channel estimation. This paper provides the various combinations of the interpolation schemes for channel estimation in time and frequency dimensions, and then analyzes the performance of the various combinations through the computer simulation. The results of computer simulation show that the combination of the linear interpolation in the time dimension and then DFT-based interpolation in the frequency dimension can obtain the best performance among the considered combinations.