• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.12
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• pp.863-866
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• 2013

SiC crystal ingots were grown on 6H-SiC dual-seed crystals with different surface roughness and different seed orientation by a PVT (Physical Vapor Transport) method. 4H and 15R-SiC were grown on seed crystal with high root-mean-square (rms) value. The polytype of grown crystal on the seed crystal with lower rms value was confirmed to be 6H-SiC. On the other hand, all SiC crystals grown on seed crystals with different seed orientation were proven to be 6H-SiC. The surface roughness of seed crystals had no effect on the crystal structure of the grown crystals. However, the crystal quality of 6H-SiC single crystals grown on the on-axis seed were revealed to be slightly better than that of 6H-SiC crystal grown on the off-axis seed.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.222-228
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• 2018

Benzene is one of the most widely used basic materials in the petrochemical industry. Generally, benzene exists as a mixture with alcohols rather than as a pure substance. Further, the alcohols-added mixtures usually exhibit an azeotropic composition. In this context, knowledge of the phase equilibrium behavior of the mixture is essential for its separation and purification. In this study, the vapor-liquid equilibrium data were measured in favor of a recirculating VLE apparatus under constant pressure for the 1 - propanol / benzene system. The measured vapor - liquid equilibrium data were also correlated by using the UNIQUAC and WILSON models and the thermodynamic consistency test based on the Gibbs/Duhem equation was followed. The results of the phase equilibrium experiment revealed RMSEs (Root Mean Square Error) and AADs (Average Absolute Deviation) of less than 0.05 for both models, indicating a good agreement between the experimental value and the calculated value. The results of the thermodynamic consistency test also confirmed through the residual term within ${\pm}0.2$.

• The Journal of the Korea Contents Association
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• v.21 no.5
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• pp.996-1003
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• 2021

The purpose of this study is to evaluate the reliability of repeated measurements of several dental scanners. Blue-lighted scanners, white-light scanners and optical-type scanners are used in the study of repeatability in this study. The measurement results were calculated as root mean square (RMS) and the significance level was confirmed by applying the 1-way ANOVA statistical technique (𝛼=.05). According to the statistical analysis, the scanner with the largest RMS value was Z-opt group (38.2 ㎛. Next, D-white was 35.2 ㎛ and the group with the lowest RMS value was I-blue (34.1 ㎛). The comparison of RMS means between each group was not significant (p>.05). From this result, the blue light had the lowest error in repeatability of dental scanners, but no statistical significance. The conclusion of this study is that the study results are clinically acceptable.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.5
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• pp.757-762
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• 2012

In this paper, the multi feature extraction algorithm for estimation of wrist movements based on Electromyogram(EMG) is proposed. For the extraction of precise features from the EMG signals, the difference absolute mean value(DAMV), the mean absolute value(MAV), the root mean square(RMS) and the difference absolute standard deviation value(DASDV) to consider amplitude characteristic of EMG signals are used. We figure out a more accurate feature-set by combination of two features out of these, because of multi feature extraction algorithm is more precise than single feature method. Also, for the motion classification based on EMG, the linear discriminant analysis(LDA), the quadratic discriminant analysis(QDA) and k-nearest neighbor(k-NN) are used. We implemented a test targeting twenty adult male to identify the accuracy of EMG pattern classification of wrist movements such as up, down, right, left and rest. As a result of our study, the LDA, QDA and k-NN classification method using feature-set with MAV and DASDV showed respectively 87.59%, 89.06%, 91.75% accuracy.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2197-2204
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• 2015

In recent years, medical image diagnosis has growing significant momentous in the medicinal field. Brain and lung image of patient are distorted with salt and pepper noise is caused by moving the head and chest during scanning process of patients. Reconstruction of these images is a most significant field of diagnostic evaluation and is produced clearly through techniques such as linear or non-linear filtering. However, restored images are produced with smaller amount of noise reduction in the presence of huge magnitude of salt and pepper noises. To eliminate the high density of salt and pepper noises from the reproduction of images, a new efficient fuzzy based median filtering algorithm with a moderate elapsed time is proposed in this paper. Reproduction image results show enhanced performance for the proposed algorithm over other available noise reduction filtering techniques in terms of peak signal -to -noise ratio (PSNR), mean square error (MSE), root mean square error (RMSE), mean absolute error (MAE), image enhancement factor (IMF) and structural similarity (SSIM) value when tested on different medical images like magnetic resonance imaging (MRI) and computer tomography (CT) scan brain image and CT scan lung image. The introduced algorithm is switching filter that recognize the noise pixels and then corrects them by using median filter with fuzzy two-sided π- membership function for extracting the local information.

• Journal of The Korean Society of Integrative Medicine
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• v.4 no.4
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• pp.77-82
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• 2016

Purpose: The purpose of this study was to investigate the therapeutic effect of non-invasive vagus nerve stimulation by transcutaneous electrical nerve stimulation application on the autonomic nervous system of human body. Methods: Participants were seventeen healthy adults. Standard deviation of all normal N-N intervals(SDNN), root mean square of successive differences(RMSSD), low frequency(LF), high frequency(HF) were compared in pre and post Mean values after intervention. Data were analyzed in Wilcoxon's signed-ranks test. Results: The results of this study is that sistolic blood pressure and pulse rate decreased mean value after non-invasive vagus nerve stimulation by transcutaneous electrical nerve stimulation. High frequency, low frequency, SDNN, RMSSD increased mean value in heart rate variability after intervention. But that is not significant except for SDNN. Conclusion: Non-invasive vagus stimulation by transcutaneous electrical nerve stimulation effect on parasympathetic nerve stimulation, and then it might be effective method for autonomic nerve balance control.

• Journal of Internet Computing and Services
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• v.25 no.2
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• pp.57-67
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• 2024

This paper explores the potential of electromyography (EMG) as a means of gesture recognition for user input in gesture-based interaction. EMG utilizes small electrodes within muscles to detect and interpret user movements, presenting a viable input method. To classify user gestures based on EMG data, machine learning techniques are employed, necessitating the preprocessing of raw EMG data to extract relevant features. EMG characteristics can be expressed through formulas such as Integrated EMG (IEMG), Mean Absolute Value (MAV), Simple Square Integral (SSI), Variance (VAR), and Root Mean Square (RMS). Additionally, determining the suitable time for gesture classification is crucial, considering the perceptual, cognitive, and response times required for user input. To address this, segment sizes ranging from a minimum of 100ms to a maximum of 1,000ms are varied, and feature extraction is performed to identify the optimal segment size for gesture classification. Notably, data learning employs overlapped segmentation to reduce the interval between data points, thereby increasing the quantity of training data. Using this approach, the paper employs four machine learning models (KNN, SVC, RF, XGBoost) to train and evaluate the system, achieving accuracy rates exceeding 96% for all models in real-time gesture input scenarios with a maximum segment size of 200ms.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.6
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• pp.361-373
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• 2010

Analysis has been made on the tide/storm surges characteristics near the Korean marginal seas in the 2008 and 2009 years using operational ocean prediction model of the Korea Meteorological Administration(KMA). In order to evaluate its performance, its results were compared with the observed data by tidal stations around Korean Peninsula. The model used in this study predicts very well the characteristics of tide/storm surges near the Korean Peninsula. Simulated storm surges show the evident effects of Typhoons in summer season. The averaged root mean square error(RMSE) of 48 hr forecasting between the modeled and observed storm surges are 0.272 and 0.420 m in 2008 and 2009, respectively. Due to strong sea winds, the highest storm surges heights was found in summer season of 2008, however, in 2009, the high storm surges heights was also found in other seasons. When Typhoon Kalmaegi(2008) and Morokot(2009) approached to Korean Peninsular, the accuracy of model predictions is almost same as annual mean value but the precision accuracy for Typhoon Morakot is lower than of Typhoon Kalmaegi similar to annual results.

• Communications for Statistical Applications and Methods
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• v.27 no.1
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• pp.97-108
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• 2020

This paper compares several methods for estimating parameters of normal inverse Gaussian distribution. Ordinary maximum likelihood estimation and the method of moment estimation often do not work properly due to restrictions on parameters. We examine the performance of adjusted estimation methods along with the ordinary maximum likelihood estimation and the method of moment estimation by simulation and real data application. We also see the effect of the initial value in estimation methods. The simulation results show that the ordinary maximum likelihood estimator is significantly affected by the initial value; in addition, the adjusted estimators have smaller root mean square error than ordinary estimators as well as less impact on the initial value. With real datasets, we obtain similar results to what we see in simulation studies. Based on the results of simulation and real data application, we suggest using adjusted maximum likelihood estimates with adjusted method of moment estimates as initial values to estimate the parameters of normal inverse Gaussian distribution.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.131-133
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• 2014

Vibration exposure of the KTX and ITX-saemaeulho on the Gyung-Bu line was evaluated and compared in terms of human health based on ISO 2631. RMS value of KTX was calculated as much lower than ITX-saemaeulho in all travel sections. When VDV result of the two trains drived return travel from Seoul to Busan in single day is compared on the health guidance caution zone of ISO 2631, vibration exposure of KTX is safer than ITX-saemaeulho which is marginally under the caution line.