• The Journal of the Acoustical Society of Korea
• /
• v.41 no.2
• /
• pp.122-129
• /
• 2022

In this paper, we propose a method to improve the performance of Transformer-based speech recognizers using data augmentation that locally adjusts the frame rate. First, the start time and length of the part to be augmented in the original voice data are randomly selected. Then, the frame rate of the selected part is changed to a new frame rate by using linear interpolation. Experimental results using the Wall Street Journal and LibriSpeech speech databases showed that the convergence time took longer than the baseline, but the recognition accuracy was improved in most cases. In order to further improve the performance, various parameters such as the length and the speed of the selected parts were optimized. The proposed method was shown to achieve relative performance improvement of 11.8 % and 14.9 % compared with the baseline in the Wall Street Journal and LibriSpeech speech databases, respectively.

• Journal of Astronomy and Space Sciences
• /
• v.29 no.3
• /
• pp.253-258
• /
• 2012

We revisit the relation between the peak luminosity $L_{iso}$ and the spectral time lag in the source frame. Since gamma-ray bursts (GRBs) are generally thought to be beamed, it is natural to expect that the collimation-corrected peak luminosity may well correlate with the spectral time lag in the source frame if the lag-luminosity relation in the GRB source frame exists. With 12 long GRBs detected by the Swift satellite, whose redshift and spectral lags in the source frame are known, we computed $L_{0,H}$ and $L_{0,W}$ using bulk Lorentz factors ${\Gamma}_{0,H}$ and ${\Gamma}_{0,W}$ archived in the published literature, where the subscripts H and W represent homogeneous and wind-like circumburst environments, respectively. We have confirmed that the isotropic peak luminosity correlates with the spectral time lag in the source frame. We have also confirmed that there is an anti-correlation between the source-frame spectral lag and the peak energy, $E_{peak}$ (1 + z) in the source frame. We have found that the collimation-corrected luminosity correlates in a similar way with the spectral lag, except that the correlations are somewhat less tight. The correlation in the wind density profile seems to agree with the isotropic peak luminosity case better than in the homogeneous case. Finally we conclude by briefly discussing its implications.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.39 no.5
• /
• pp.313-319
• /
• 2021

The national geodetic reference frame of Korea was adopted in 2003, which is referenced to ITRF (International Terrestrial Reference Frame) 2000 at the epoch of January 1, 2002. For precise positioning based on the satellites, it should be thoroughly maintained to the newest global reference frame. Other than plate tectonic motion, there are significant events or changes such as earthquakes, antenna replacement, PSD (Post-Seismic Deformation), seasonal variation etc. We processed three years of GNSS (Global Navigation Satellite System) data(60 NGII CORS stations, 51 IGS core stations) to produce daily solutions minimally constrained to ITRF. From the time series of daily solutions, the sites with unexpected discontinuity were identified to set up an event(mostly antenna replacement). The combined solution with minimum constraints was estimated along with the velocity, the offsets, and the periodic signals. The residuals show that the surrounding environment also affects the time series to a certain degree, thus it should be improved eventually. The transformation parameters to ITRF2014 were calculated with stability and consistency, which means the national geodetic reference frame is properly aligned to the global reference frame.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.13 no.2
• /
• pp.243-251
• /
• 2010

The military has been putting great efforts into applying data communication on existing voice communication systems being used in NCW(Network Centric Warfare). Data communication will be an effective choice in one of many effort to yield a minimum kill chain, comparing to legacy voice communications, when tactical units conduct their missions. However, the required budget will be enormous, in case of the replacement of a lot of legacy communication systems with new one. As a cost-effective alternative, the tactical data communication systems using the conventional radio systems instead of the development of new radio systems has been proposed. It is mandatory, though, to ensure QoS while maintaining data communication by making use of legacy radio systems already in use. This paper focuses on the performance issues experimented and analyzed for tactical data communication through the legacy radio systems as the first step towards guaranteed QoS. We have conducted various experiments such as the transmission error rate on certain tactical messages, performance evaluation of redundant transfers, the relationship between the transmission frame size and rate of error, the identification of error points in the transmission frame, and techniques to reduce the errors in both hopping and non-hopping modes. As a result of the performance experiments, The adaptive communication module which decides the redundant transmission or the Forward Error Correction(FEC) technique by analyzing channel status and current transmission status(hopping/non-hopping) of the legacy radio should be designed. the FEC technique in non-hopping, and the redundant transmission technique in hopping mode was recommended from the result of experiment with the frame size is 20bytes in non-hopping and 10Bytes frame size in hopping mode.

• The KIPS Transactions:PartB
• /
• v.10B no.6
• /
• pp.687-694
• /
• 2003

According to the rapid increase of multimedia data quantity recently, various means of video data search has been desired. In order to process video data effectively, it is required that the content information of video data is loaded in database and semantic-based retrieval method can be available for various query of users. Currently existent contents-based video retrieval systems search by single method such as annotation-based or feature-based retrieval, and show low search efficiency and requires many efforts of system administrator or annotator form less perfect automatic processing. In this paper, we propose semantic-based video retrieval system which support semantic retrieval of various users by feature-based retrieval and annotation-based retrieval of massive video data. By user's fundamental query and selection of image for key frame that extracted from query, the agent gives the detail shape for annotation of extracted key frame. Also, key frame selected by user become query image and searches the most similar key frame through feature based retrieval method that propose. Therefore, we design the system that can heighten retrieval efficiency of video data through semantic-based retrieval.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.34S no.12
• /
• pp.10-18
• /
• 1997

The parallel trabutary signals in the SDH-based transmission system have the frame phase skew due to uneven transmission delays in the data and the clock path. This phase skew must be eliminated prior to synchronously multiplexing process. A new twenty-four channel, 51.84Mb/s DFPA(Digital Frame Phase Aligner) has been designed and fabricated in 0.8.mu.m CMOS gate array. This unique device phase-aligns the skewed input signals with refernce frame synchronous signal and reference clok for subsequent synchronous multiplexing process. the performance of fabricated device is evaluated by the STM-16 transmission system and DS-3 meansurement set. The frame phase margin of +2/-3 bit periods has been demonstrated.

• Journal of the Korean Society of Safety
• /
• v.13 no.2
• /
• pp.13-21
• /
• 1998

This is a study on the natural vibration characteristics of Vehicle frame. Nowadays, many trucks freight the over-load, do the car designers consider the over-load about 200% in the design. It's necessary to make the model of a vehicle and simulate it for the test of driving condition, durability and vibration behavior before the vehicle is manufactured. If it is possible to make a simulation using the static and dynamic analysis, this is very useful in accomplishing an optimal design of the vehicle. In this paper, we studied the vibration characteristics of a truck body frame. The automobile body frame model for experiment is made smaller than real size frame with the ratio of 1/10. The vibration characteristics of a frame is considered as one of main factors in analyzing and improving the problem for ride comfort, noise and vibration reduction. Therefore, we experimented two method to neglect the nonlinearity. First is bolting and second is welding at the joint section. We compared computer simulation results and experimental data.

• Proceedings of the KIEE Conference
• /
• 2006.10c
• /
• pp.467-469
• /
• 2006

In wireless network environments, as users' demands on high-speed data communications due to increase of multi-media services, the necessity of new high-speed WLAN technologies has appeared. Nowaday, IEEE is standardizing a new WLAN protocol caned as IEEE 802.11n. To effectively use wireless resources, IEEE 802.11n introduces MAC aggregation function which is similar to that in IEEE 802.11e. In case of transmitting several frames without MAC aggregation, the frames include individual frame header and trailer, and their corresponding acknowledgement frames can appear on wireless link. However, if they are aggregated into single MAC frame, we can reduce the number of used bits due to frame headers/trailers and also remove redundant acknowledgement frames. In this paper, we explain two different MAC frame aggregation methods for IEEE 802.11e and IEEE 802.11n and evaluate their throughput by simulations.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.2
• /
• pp.107-113
• /
• 1998

Grinding operation has difficulty in satisfying the qualitative knowledge based on the skilful expert as well as the quantitative data for all user. Design of grinding database based on the frame-based model is more effective method for utilizing the empirical and qualitative knowledge. In this paper. basic strategy to develop the grinding database by taking frame-based model, which is strongly dependent upon experience and intuition, is described. Grinding database based on the frame based model for designing the interaction and inference among the slots is accomplised by the object-oriented paradigm system.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.21 no.3
• /
• pp.368-375
• /
• 2012

Durability performance evaluation of automotive components is very important and time consuming task. In this paper, to reduce vehicle component development time and cost virtual testing simulation technology is used to evaluate durability performance of a passenger car front aluminum sub-frame. Multibody dynamics based vehicle model and virtual test simulation model of a half car road simulator are validated by comparisons between rig test results and simulation results. Durability life prediction of the sub-frame is carried out using the model with road load data of proving ground which can evaluate accelerated durability life. We found that the durability performance of the sub-frame is sufficient and it can be predicted within short time compared to rig test time.