• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.10 s.241
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• pp.1119-1129
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• 2005

A new measurement system of wall pressure fluctuations on a rotating machinery, composed of digital recording device, was developed and evaluated. The small-sized digital recording device was attached on the rotating machinery and then was detached for data reduction. In order to obtain the system transfer function of the digital recording system, a dynamic calibration was performed utilizing the signal from a 1/8 inch B&K microphone as input. The time history of the unsteady pressure was then reconstructed from the output of the sensor by using this transfer function. The reconstructed pressure signals showed good agreement with the reference signal in both temporal and spectral sense. This sensor was then used to measure the wall pressure fluctuations on a rotating blade. An array of microphones were installed on the blade in the circumferential and radial directions. Various statistical moments were obtained from the measurement data set. Comparison of these quantities with the existing studies demonstrated satisfactory agreement. These tests give credence to the relevance and reliability of this device for applications in more complicated turbulent rotating machineries.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.382-385
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• 2003

Introduction of digital broadcasting service does not only mean the change of information transmission method but also the change of total broadcasting system. In past day, Television was only received one-sided information from broadcasting station, but digital broadcasting means that digital television becomes the most important means of information transmission by the introduction of new programming, lots of channels, data service, multi communication. In the age of the digital broadcasting, the recording and replay medium's interest is getting higher. The medium is able to record more than 24 hours' digital broadcasting programs without additional tapes. In this paper the recording and replay device using HDD was implemented and device driver based on linux was programmed. It has Intel PXA250 processor and hard disk is used as storage equipment. And transport Stream is saved on hard disk through PXA250's data bus. FIFO is added to solve the different saving speed and FPGA is also added to display the saved data.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.26 no.2
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• pp.104-111
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• 2015

Background and Objectives : Acoustic analysis of voice could be influenced so much by the quality of voice files which were recorded by recording device. In clinical practice, voice files that were recorded by analysis program directly or portable digital recording device were analyzed mostly. This study examined the feasibility of using Galaxy smartphone recordings for acoustic analysis of voice. Materials and Methods : Acoustic measures were compared between voice signals recorded from 30 normal speakers (15 males and 15 females) through Galaxy smartphone, portable digital recording device and CSL. Fo, jitter, shimmer, NHR (Noise-Harmony ratio) and Formant frequencies were analyzed by MDVP. Results : Fo, Jitter, Shimmer, NHR and formant frequencies from 3 devices were no significantly difference. The intraclass correlation coefficient (ICC) was higher between each of the voice perturbation measures. Conclusion : The findings indicated that Galaxy smartphone recording system was useful device for acoustic analysis of voice. Furthermore, Galaxy smartphone can be applied widely in various way for acoustic analysis of voice.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.7
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• pp.940-944
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• 2014

In this research, we designed representative motion patterns that possibly occurred in sleep situation and evaluated the feasibility of the smartphone based movement recording technique. For this, we designed 7 motions such as posture change, head movement, arm movement (vertical, horizontal), leg movement and hand movement (flipping, folding). Movement was recorded by using the smartphone and the actimetry device simultaneously for comparing the feasibility of smartphone based recording. As a result of experiment, we found that the smartphone based movement recording well reflects the body movement, however, it shows the limitation in recording the small local movement such as hand motion compared with the reference actimetry device, Actiwatch.

• Journal of the Korea Safety Management & Science
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• v.6 no.3
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• pp.303-309
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• 2004

Many system devices for fluoroscopic and general X-ray studies in diagnostic radiographic system have been being changed from analog mode to digital mode. In addition, among diagnostic imaging and radiologic examinations, fluoroscopic studies that requires functional diagnosis is being widely used. The video recording method of fluoroscopic studies has been useful in functional image diagnosis and dynamic image observation, but the utility of its image quality is being reduced because of limitation in setting play segments of the video player, inconvenience of play, difficulties in preserving reproduced images, the change of image quality, etc. In order to complement these shortages, it is necessary to facilitate access to patient diagnosis information such as storing, editing and sharing functional diagnosis images in response to the trend of the digitalization of digital radiographic & fluoroscopic system(DRF). Thus this study designed and implemented a device of storing functional dynamic images real time using a computer rather than existing video recording, aiming at contribution to functional image diagnosis.

• 한국가시화정보학회:학술대회논문집
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• 2005.12a
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• pp.1-5
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• 2005

The digital HPTV velocity field measurement consists of four steps: recording, numerical reconstruction, particle extraction and velocity extraction. In the velocity extraction process, we improved PTV algorithm to extract the displacement of particle each placed in 3D space. Because a digital recording device was used, some factors such as a spatial resolution, numerical aperture, and particle concentration can affect the performance of the digital HPTV. Especially, a particle concentration ($C_{o}$) affected tile reconstruction efficiency in numerical reconstruction and particle extraction process. In this paper, the reconstruction efficiency was analyzed experimentally with different particle concentration. Optimal reconstruction efficiency was shown in the range of $C_{o}$=$13\∼15$ particles/$mm^{3}$.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.4
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• pp.25-36
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• 2001

• Journal of Digital Convergence
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• v.19 no.7
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• pp.209-215
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• 2021

This study is a system development for voice information protection equipment in major meetings and places requiring security. Security performance and stability were secured with information leakage prevention technology through generation of false noise and ultrasonic waves. The cutoff frequency band for blocking the leakage of voice information, which has strong straightness due to the nature of the radio wave to the recording prevention module, blocks the wideband frequency of 20~20,000Hz, and the deception jamming technology is applied to block the leakage of voice information, greatly improving the security. To solve this problem, we developed a system that blocks the recording of a portable smartphone using a battery, and made the installation of a separate device smaller and lighter so that customers do not recognize it. In addition, it is necessary to continuously study measures and countermeasures for efficiently using the output of the anti-recording speaker for long-distance recording prevention.

• ETRI Journal
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• v.31 no.1
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• pp.10-20
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• 2009

In this paper, a video broadcasting system between a home-server-type device and a mobile device is proposed. The home-server-type device can automatically extract semantic information from video contents, such as news, a soccer match, and a baseball game. The indexing results are utilized to convert the original video contents to a digested or arranged format. From the mobile device, a user can make recording requests to the home-server-type devices and can then watch and navigate recorded video contents in a digested form. The novelty of this study is the actual implementation of the proposed system by combining the actual IT environment that is available with indexing algorithms. The implementation of the system is demonstrated along with experimental results of the automatic video indexing algorithms. The overall performance of the developed system is compared with existing state-of-the-art personal video recording products.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.536-542
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• 2016

Freight and passenger transport operators must converts the operation records of digital operation recording device (Digital Tachograph) that is mounted on their vehicle in a certain format, and report them to governmental agencies. However, for most of the individual carrier who cannot access a computer environment easily and are not familiar with the use of computer, it has given a big inconvenience to them because the procedures for entering the data obtained from the operation are so complicate. Therefore, in this study, a mobile system for converting the operation record file to request form of a government agency is designed and developed, so that the converted file can be submitted to the government agency in a simple way through the personal mobile device. By entering the data obtained from an actual operation recording device into the system, converting the data in the proposed algorithms, and checking the contents of the converted file in data viewer, it was confirmed that the proposed functions is working properly in the system.