• Geophysics and Geophysical Exploration
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• v.25 no.2
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• pp.59-70
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• 2022

Recent studies demonstrate that machine learning has expanded in the field of seismic interpretation. Many convolutional neural networks have been developed for seismic sequence identification, which is important for seismic interpretation. However, expense and time limitations indicate that there is insufficient data available to provide a sufficient dataset to train supervised machine learning programs to identify seismic sequences. In this study, patch division and data augmentation are applied to mitigate this lack of data. Furthermore, to obtain spatial information that could be lost during patch division, an artificial channel is added to the original data to indicate depth. Seismic sequence identification is performed using a U-Net network and the Netherlands F3 block dataset from the dGB Open Seismic Repository, which offers datasets for machine learning, and the predicted results are evaluated. The results show that patch-based U-Net seismic sequence identification is improved by data augmentation and the addition of an artificial channel.

• The Journal of the Acoustical Society of Korea
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• v.28 no.2
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• pp.96-106
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• 2009

In this paper, correlation between the headphone's acoustical characteristics and the subjective preferences is analyzed, and a possibility of predicting the subjective preferences using the acoustical characteristics is investigated, The headphone's acoustical characteristics include the total harmonic distortions, the variation of the frequency response which were measured by separate channel and the inter-aural correlation coefficients, Those characteristics were measured in a noise-free anechoic chamber, using a head and torso simulator, The subjective preferences were scored in terms of loudness, clearness, spaciousness, fullness and overall impression, In the subjective listening test, 12 subjects were participated who have plentiful listening experiences, The programs include 5 kinds of musics; korean popular song, pop song, light music, male-voice and classic, The 8 models of the headphones were employed, including 4 closed-type circumaural headphones, 2 open-type supraaural headphones and 2 intra-concha headphones, A significant test was carred on the results from the subjective test, using a two-way ANOVA test, The correlation coefficients between the acoustical parameters and the subjective preferences were computed, Experimental results showed that the variation of the magnitude of frequency response measured from a right channel revealed higher correlation with the subjective preferences. Whereas the inter-aural correlation coefficients have very low correlation coefficients.

• Korean Journal of Remote Sensing
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• v.29 no.1
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• pp.11-20
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• 2013

Space-borne Synthetic Aperture Radar(SAR) has been one of the most effective tools for monitoring quantitative oceanographic physical parameters. The Doppler information recorded in single-channel SAR raw data can be useful in estimating moving velocity of water mass in ocean. The Doppler shift is caused by the relative motion between SAR sensor and the water mass of ocean surface. Thus, the moving velocity can be extracted by measuring the Doppler anomaly between extracted Doppler centroid and predicted Doppler centroid. The predicted Doppler centroid, defined as the Doppler centroid assuming that the target is not moving, is calculated based on the geometric parameters of a satellite, such as the satellite's orbit, look angle, and attitude with regard to the rotating Earth. While the estimated Doppler shift, corresponding to the actual Doppler centroid in the situation of real SAR data acquisition, can be extracted directly from raw SAR signal data, which usually calculated by applying the Average Cross Correlation Coefficient(ACCC). The moving velocity was further refined to obtain ocean surface current by subtracting the phase velocity of Bragg-resonant capillary waves. These methods were applied to Envisat ASAR raw data acquired in the East Sea, and the extracted ocean surface currents were compared with the current measured by HF-radar.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.2
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• pp.33-41
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• 2001

Currently, the compression is one of the most important technology in multimedia society. Audio files arc rapidly propagated throughout internet Among them, the most famous one is MP-3(MPEC-1 Laver3) which can obtain CD tone from 128Kbps, but tone quality is abruptly down below 64Kbps. MPEC-II AAC(Advanccd Audio Coding) is not compatible with MPEG 1, but it has high compression of 1.4 times than MP 3, has max. 7.1 and 96KHz sampling rate. In this paper, we propose an algorithm that decreased the capacity of AAC encoding computation but increased the processing speed by optimizing psychoacoustic model which has enormous amount of computation in MPEG 2 AAC encoder. The optimized psychoacoustic model algorithm was implemented by C++ language. The experiment shows that the psychoacoustic model carries out FFT(Fast Fourier Transform) computation of 3048 point with 44.1 KHz sampling rate for SMR(Signal to Masking Ratio), and each entropy value is inputted to the subband filters for the control of encoder block. The proposed psychoacoustic model is operated with high speed because of optimization of unpredictable value. Also, when we transform unpredictable value into a tonality index, the speed of operation process is increased by a tonality index optimized in high frequency range.

• The Journal of Society for e-Business Studies
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• v.22 no.4
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• pp.141-158
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• 2017

Along with IT development, customers are getting more easily to express their opinions using various IT channels. In this situation, complaint management is a pressing issue for companies to acquire and maintain loyal customers with low cost. Most of previous studies have investigated customer complaint information by quantitative variables such as demographic information, transaction information, or complaint frequency, but studies focusing on qualitative aspects of complaint information are limited. Therefore, this paper considers the possibility for customers to leave even when they complain occasionally or briefly. This paper analyzes the quantitive aspects as well as the qualitative aspects using sentiment analysis with Exit-voice theory. The dataset contains 268,364 inquiries of 46,235 customers obtained from a contact center of a private security company in Korea. This paper carries out logistic regression and the results imply that the customers's explicit response and their implicit sentiment have different effect on customers leave. This study is expected to provide useful suggestions for the effective complaint management.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.4
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• pp.227-236
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• 2016

In the present experimental study, the effect of gas- and liquid-injected methods on the formation of bubble and liquid slug at the merging micro T-junction of a square microchannel with dimensions $600{\mu}m{\times}600{\mu}m$ was investigated. Nitrogen and water were used as test fluids. The superficial velocities of the liquid and gas were in the range of 0.05 - 1 m/s, and 0.1 - 1 m/s, respectively, where the Taylor flow was observed. The bubble length, liquid slug length, bubble velocity, and bubble generation frequency were measured by analyzing the images captured using a high-speed camera. Under similar inlet superficial velocity conditions, in the case of gas injection to the main channel at the merging T-junction (T_gas-liquid), the lengths of the bubble and liquid slug were longer, and the bubble generation frequency was lower than in the case of liquid injection to the main channel at the merging T-junction (T_liquid-gas). On the other hand, in both cases, the bubble velocity was almost the same. The previous correlation proposed using experimental data for T_liquid-gas had predicted the present experimental data of bubble length, bubble velocity, liquid slug length, and bubble generation frequency for T_gas-liquid to be ~24%, ~9%, ~39%, ~55%, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7C
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• pp.726-732
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• 2003

The paper proposes a motion estimation (ME) technique to reduce computational complexity. It is achieved by skipping ME process for macro-blocks decided to be in no need of the operation. Thus, it is called ME skipping technique(MEST). In general, the ME is composed of integer pixel precision ME (IME) followed by half pixel precision ME (HME). The MEST is performed just before an IME process and makes a decision on skipping the IME process according to a criterion based on ME errors of adjacent macro-blocks (MBs) already encoded. When the IME process for a MB is decided to be skipped, which is called ME skip mode, the IME process is skipped and the integer pixel precision motion vector of the MB is just replaced by a predicted vector and used as the input of HME. On the other hands, the IME processes for MBs in ME non-skip mode are not skipped but normally performed. Accordingly, the MEST is very effective to reduce computational complexity when MBs in ME skip mode is abundant. In addition, when the MEST is applied to video encoder, it contributes to more accurate rate control and more robusaess for channel errors. It is experimentally shown that the MEST has the above advantages while maintaining good reconstructed image quality.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.732-740
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• 2019

Evaporative humidification using a humidifying element is widely used for humidification of a building or a data center. The performance of a humidifying element is commonly expressed as humidification efficiency, which is used independent of air temperature, humidity and water temperature. In this study, a series of tests were conducted at two air conditions (data center and commercial building) using two different humidifying elements (cellulose/PET and Glasdek) changing the frontal air velocity and water temperature. Results showed that the measured humidification efficiency was dependent on the air condition and water temperature. In fact, even dehumidification occurred at the inlet of the humidifying element at the air condition of commercial building. The reason was due to the inlet water temperature, which was lower than the dew point air temperature. As the difference between the inlet water and the dew point air temperature increased, the humidification efficiency decreased. This suggest that proper thermal model should account for the inlet region, where the amount of moisture transfer may be different from the other part of the humidification element. A simple analysis on the thermal performance of the cellulose/PET humidification element showed that the Sherwood number was adequately predicted, whereas the friction factor was ovepredicted, probably due to the simplification of the channel geometry and the neglection of the water film on the element surface.

• 한국노년학
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• v.38 no.1
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• pp.27-45
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• 2018

The purpose of this study was to identify between the successful aging-related predictive factors and the successful aging in the middle aged office. The predictive factors of successful aging such as subjective health condition, cognitive functions, self-esteem, and social support were confirmed by the existing literature. The population of the study was the middle aged office employees, who are generally defined an age group from 40 to 60. The sample of this study was targeted to employees working at companies registered to securities, KSDAQ, and KONEX in Korea. SPSS WIN 23.0 and AMOS 21.0, and M-plus 6.12 were used for the data analysis. The findings of this study were presented below. First, the result of the structural relationship between the predictive factors of successful aging (subjective health condition, cognitive function, self-esteem, and social support) and successful aging was appropriate as RMSEA=.059, TLI=.932, CFI=.944. Second, subjective health condition and social support were significant variables for successful aging but cognitive function and self-esteem were not significant. Third, social support, which is a social factor, was the most influential among other variables. Based on the results, theoretical and practical implications were presented.

• Proceedings of the Korea Association of Information Systems Conference
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• 2003.05a
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• pp.55-73
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• 2003

As the development of wireless technologies continue, mobile stock trading has become a new channel for companies to reach their customers. This study examines the factors affecting customer acceptance of mobile stock trading services. The research model based on the previous studies was established and the research hypotheses were generated. The sample was divided into users and nonuser groups. The test results show that relative advantage and social influence are positively related to intention to accept mobile services as well as in intention to reuse, security risk is negatively related to intention to reuse, frequency of trading is positively related to intention to reuse, cost burden is negatively related to the probability of using mobile stock trading services, and social influence is positively related to the probability of using mobile services. The results also support that information quality and response time are positively related to relative advantage, and interface quality is negatively related to complexity. It is considered that the study results may help managers to increase customer use of mobile stock trading services.