• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.4
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• pp.332-338
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• 2022

This study proposes a battery state-of-health estimation method by applying a feature extraction technique. The technique that can improve estimation performance is the process of identifying and extracting meaningful data. To apply a data-driven-based aging state estimation method to batteries, health indicators are used as training data. However, limitations occur in extracting health indicators from charge/discharge cycles. This study proposes a deep-learning-based battery state-of-health estimation method that applies feature extraction techniques to compensate for this problem. According to the performance evaluation result of the proposed method, it has a low estimation error of 0.3887% based on an absolute error evaluation method.

• Journal of Korea Soil Environment Society
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• v.3 no.1
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• pp.83-92
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• 1998

This study presents a relationship between gas quantity and measurement resistance using the bubble meter, the water head indicator and the rotor meter from the gas vent sanitary landfill. From the one-dimensional analyses and experiments, the below results have been obtained. The gas volume sourcing from the gas vent depends on the permeability of final cover soil, its cover depth and distance between the gas vents. The total gas volume producing in the interested domain may be accurately measured by the bubble meter, the water head indicator and the rotor meter if the clay is used for the final cover soil. The required times approaching to the steady-state are different with respect to the flow meters, one day is for the bubble meter and the water head indicator and one hour for the rotor meter.

• Physical Therapy Rehabilitation Science
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• v.8 no.4
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• pp.218-224
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• 2019

Objective: This reliability study examined the effects of applying varying induced inward pressures using a transducer placed at 0° neutral ankle position (NEU) and 15° ankle dorsiflexion (DF) on tibialis anterior (TA) muscle thickness using a custom-made device with a force indicator during rehabilitative ultrasound imaging. Design: Cross-sectional study. Methods: Twenty-four healthy subjects were recruited in this study. Two examiners measured the muscle thickness of the TA at 0° NEU and 15° DF in 3 conditions of inward pressures (1.0 N, 2.0 N, and 4.0 N) using a custom-made holder. The muscle thickness was measured three times for each of the conditions arranged in random order. For intra- and inter-rater reliability, the intraclass correlation coefficients (ICCs) with 95% confidence intervals, standard error of measurement, minimal detectable change, and coefficient of variation were analyzed. One-way repeated measures analysis of variance was conducted for investigating changes of TA muscle thickness according to the inward pressures of the transducers. Results: The intra-rater reliability of TA muscle thickness measurement was excellent (ICC_3,1: 0.92-0.96) for all conditions (at both ankle joint angles per varying inward pressure). Likewise, the inter-rater reliability of TA muscle thickness measurement was excellent (ICC_2,1: 0.89-0.97) under same conditions. The mean of TA thickness showed the trend of decreasing significantly with increased inward pressures at all ankle joint angles (p<0.05). Conclusions: Use of this custom-made device with a force indicator is useful to accomplish the high intra- and inter-rater reliability of TA muscle thickness measurement at both ankle joint angles in reducing the measurement error.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.1
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• pp.25-30
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• 2024

Smart City, a key application area of the AIoT (Artificial Intelligence of Things), provides various services in safety, security, and healthcare sectors through location tracking and location-based services. an IPS (Indoor Positioning System) is required to implement location-based services, and wireless communication technologies such as WiFi, UWB (Ultra-wideband), and BLE (Bluetooth Low Energy) are being applied. BLE, which enables data transmission and reception with low power consumption, can be applied to various IoT devices such as sensors and beacons at a low cost, making it one of the most suitable wireless communication technologies for indoor positioning. BLE utilizes the RSSI (Received Signal Strength Indicator) to estimate the distance, but due to the influence of multipath fading, which causes variations in signal strength, it results in an error of several meters. In this paper, we conducted research on a path loss model that can be applied to BLE IPS for proximity services, and confirmed that optimizing the free space propagation loss coefficient can reduce the distance error between the Tx and Rx devices.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.293-297
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• 2011

Purpose: This study was to know the correlation among refractive error and the dimensions of ocular components on older adults. Methods: The subjects were 95 older age who had no eye diseases. The refractive error, corneal radius, corneal diopter, axial length, anterior chamber depth and lens thickness were measured and analysed. Results: The axial length(AL)/corneal radius(CR) ratio was positively correlated with the corneal diopter, axial length, the anterior chamber depth. Then it was negatively correlated with corneal radius. It was shown that the highest correlation was between the corneal diopter and axial length (r = -0.545, p = 0.000). The spherical equivalent of the refractive error was negatively correlated with the AL/CR ratio. Conclusions: It was shown that the AL/CR ratio was a very important indicator for diagnosing the refractive error of the old age.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.753-757
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• 2003

In this paper, We propose an efficient iteration decoding control method with variable iteration decoding for iteration codes decoding. As the number of iterations increases, the bit error rate and frame error rate of the decoder decrease and the incremental improvement gradually diminishes. However, as the iteration decoding number is increase, it require much delay and amount of processing for decoding. Thus we propose variable iteration control method to adapt variation of channel using Frame Error-Check indicator. Therefore, the CRC method requires the fewest iterations and less computation than the CE method and the SCR methods.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.288-295
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• 2003

An adaptive procedure in finite element analysis is presented by p-refinement of meshes in conjunction with a posteriori error estimator that is based on the recovery technique. In case of the recovery technique, the SPR(superconvergent patch recovery) approach has been modified for p-adaptive mesh refinement. The strategy of finding a nearly optimal distribution of polynomial degrees on a fixed finite element mesh is discussed such that a particular element has to be refined automatically to obtain an acceptable level of accuracy by increasing p-levels non-uniformly. To verify the proposed algorithm, the limit value approach is proposed which utilizes the exact strain energy computed from the extrapolation equation. A new pre-processor is developed for the p-version finite element program in which the vector graphic editor is used for the automatic generation of node connection and coordinate by halfedge solid data structure according to uniform or nonuniform p-distribution. The general 2-D algorithm is also developed to generate face modes and internal modes in accordance with different mesh types. The quality of the error estimator is investigated with the help of two mumerical examples. The results show that the sequences of p-distributions obtained by the proposed error indicator closely follow the optimal trajectory.

• Journal of Pharmaceutical Investigation
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• v.37 no.6
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• pp.377-395
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• 2007

Near infrared(NIR) spectral data have been used for the noninvasive analysis of various biological samples. Nonetheless, absorption bands of NIR region are overlapped extensively. It is very difficult to select the proper wavelengths of spectral data, which give the best PCR(principal component regression) models for the analysis of constituents of biological samples. The NIR data were used after polynomial smoothing and differentiation of 1st order, using Savitzky-Golay filters. To find the best PCR models, all-possible combinations of available principal components from the given NIR spectral data were derived by in-house programs written in MATLAB codes. All of the extensively generated PCR models were compared in terms of SEC(standard error of calibration), $R^2$, SEP(standard error of prediction) and SECP(standard error of calibration and prediction) to find the best combination of principal components of the initial PCR models. The initial PCR models were found by SEC or Malinowski's indicator function and a priori selection of spectral points were examined in terms of correlation coefficients between NIR data at each wavelength and corresponding concentrations. For the test of the developed program, aqueous solutions of BSA(bovine serum albumin) and glucose were prepared and analyzed. As a result, the best PCR models were found using a priori selection of spectral points and the final model selection by SEP or SECP.

• Journal of Electrical Engineering and Technology
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• v.6 no.6
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• pp.883-887
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• 2011

Location-based service (LBS) is becoming an important part of the information technology (IT) business. Localization is a core technology for LBS because LBS is based on the position of each device or user. In case of outdoor, GPS - which is used to determine the position of a moving user - is the dominant technology. As satellite signal cannot reach indoor, GPS cannot be used in indoor environment. Therefore, research and study about indoor localization technology, which has the same accuracy as an outdoor GPS, is needed for "seamless LBS". For indoor localization, we consider the IEEE802.11 WLAN environment. Generally, received signal strength indicator (RSSI) is used to obtain a specific position of the user under the WLAN environment. RSSI has a characteristic that is decreased over distance. To use RSSI at indoor localization, a mathematical model of RSSI, which reflects its characteristic, is used. However, this RSSI of the mathematical model is different from a real RSSI, which, in reality, has a sensitive parameter that is much affected by the propagation environment. This difference causes the occurrence of localization error. Thus, it is necessary to set a proper RSSI model in order to obtain an accurate localization result. We propose a method in which the parameters of the propagation environment are determined using only RSSI measurements obtained during localization.

• The Korean Journal of Applied Statistics
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• v.27 no.2
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• pp.227-237
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• 2014

We use the regression model with the indicator variables in the case that we use qualitative variables as some predictor variables in regression analysis. We use the ANCOVA(Analysis of Covariance) model when comparing the response variable among groups while statistically controlling for variation in the response variable caused by a variation in the covariate. DD-plot can be used as a graphical exploratory data analysis tool before the confirmatory data analysis. With the DD-plot, we can discriminate the difference of groups in the regression model with the indicator variables or the ANCOVA model at a glance. Making DD-plot does not demand the statistical model assumption about error terms in regression model. Several examples show the usefulness of DD-plots as a graphical exploratory data analysis tool for the regression analysis.