• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.555-558
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• 1997

A new approach to silent MR imaging using a rotating DC gradient has been explored and experimentally studied. As is known, acoustic or sound noise has been one of the major problems in handling patients, mainly due to the fast gradient pulsings in interaction with the main magnetic field. The sound noise is also proportionally louder as the magnetic field strength becomes larger. In this article, we have described a new imaging technique using a mechanically rotating DC gradient coil as an approach toward silent MR imaging, i.e., a mechanically rotated DC gradient effectively replaces both the phase encoding as well as the readout gradient pulsings and data obtained in this manner provides a set of project ion data which later can be used or the projection reconstructionorwithsomeinterpolation techniques one can also perform conventional 2-D FFT (Fast Fourier Transform) image reconstruction. We found, with this new technique, that the sound noise intensity compared with the conventional imaging technique, such as spin echo sequence, is reduced down to -20.7 dB or about 117.5 times. The experimental pulse sequence and its principle are described and images obtained by the new silent MR imaging technique are reported.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.1
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• pp.3-9
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• 2003

In an apartment building, the impact sound from upstairs has been regarded as a main source of noise causing discontentment among occupants. To set the optimum design for sound insulation. it is nesessary to suggest the useful tools or technique that predict the floor impact sound. The purpose of this study is to investigate the applicability of the theory of sound radiation. We measured the vibration acceleration levels on the interior structures and predicted the sound pressure level of the room by using them. The result show that the predicted value, in general, were in good agreement with the measured values within 5∼10% in error rate.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.6
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• pp.847-854
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• 2013

This paper implements a smartphone application for sound recording and player of mobile learning. Due to its ubiquitous nature, smartphones could be used anytime anywhere, and because they combine an audio and a microphone, the application for sound recording and player that this paper suggests can be easily and cost effectively developed without additional infrastructure. This paper also explains a technique which processes data of music lyrics. The technique is built on a database technology by using SQLite, a DBMS combined in a platform of android. Thus, as long as the smartphone application for sound recording and player is developed and the mobile phone has sound source files, learners could record their own voices to the sound. Therefore, we expect the learners without additional infrastructure to enable mobile learning.

• Journal of Korea Entertainment Industry Association
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• v.10 no.4
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• pp.77-92
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• 2016

In this study, the relationship of images and sounds of the animations "Dots" and "Loops" which Norman McLaren animated with his Animated sound technique when he worked at Guggenheim museum at New York, are analyzed through the audiovisual analysis theory by Michel Chion, and through the theory of synchronism/asynchronism and parallelism/counterpoint by Siegfried Kracauer. For the results of the analysis, there are a few difference between "Dots" and "Loops" regarding the aspect of sound arrangement and expressive aspect of abstract animation. However, there are being of two main elements of sound, composing with monophony sound, making musical structure with sound effects, and the emphasizing of parallelism with synchronization bewteen images and sounds in common with both "Dots" and "Loops". In "Dots" and "Loops", there are close correlations between pitch of sound and arrangement/shape of image, between loudness of sound and size of image, and between length of sound and length/shape of image. The image and sound of "Dots" and "Loops" have equal relationship each other, rather than subordinate relationship according as image become sound and the sound become new image with the animated sound technique. "Dots" and "Loops" show tendency of minimal art and music video. Since these two films, and remind about the new approach to sound creation in today's animation production.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.2
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• pp.81-90
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• 1998

Noise produced by surface transportation vehicles affects our daily lives, penetrating wherver man lives or works. In this paper, a theoretical model has been studied to describe the sound radiation by the surface vibration of in-service tires and studied about an experiment on sound radiation characteristic due to tire vibration. When a tire is analyzed, it has been modeled as a curved beams with distributed sprongs and dash-pots which represent the radial, tangential stiffnes and damping of tire, respectively. The experimental investigation for the sound radiation of a radial tire has been made. Based on the sound intensity and STSF(Spatial Transformation of Sound Field) techniques. the sound pressure and the sound radiation are measured. The comparison of numerically analyzed results with experimental results was made seperately for the tire in rotation. As a result of this study, a program for the prediction of the tire vibration sound radiation was intended to by developed which enables a designer of a tire to foresee the influence of the various design factors on the tire vibration sound radiation.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.1
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• pp.83-92
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• 2000

Sound intensity method is well known as a visualization technique of sound field or sound propagation in noise control. Sound intensity or energy flux is a vector quantity which describes the amount and the direction of net flow of acoustic energy at a given position. Especially two dimensional sound intensity method is very useful in evaluating periodic characteristics and acoustic propagation mode of noise source. In this paper, we have studied the noise source Identification, acoustic sound field analysis, and characteristics of noise source of rotary compressor and scroll compressor for air conditioner using complex sound intensity method. Also we proposed a now method of time domain analysis which is used in evaluating of position of noise source in rotary and scroll compressor in this paper This paper presents the advantage, simplicity and economical efficiency of this method by analysing the characteristics of noise source with two dimensional complex sound intensity simultaneously.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.4 s.97
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• pp.412-420
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• 2005

This article proposes analytical solutions for sound radiation from radial vibration modes of a thick annular disk. Structural eigensolutions are calculated using the transfer matrix method. The far-field sound pressure distribution is obtained using two alternate methods. In the first method, pressure is calculated using the Rayleigh integral technique. The second method treats sound radiating radial surfaces as cylindrical radiators of finite length. The Sinc function approach is employed for calculations. Acoustic powers and radiation efficiencies of radial modes are also determined from the far-field sound pressure calculations. Analytical predictions match well with measured data as well as computational results from a finite element code in terms of structural eigensolutions and from a boundary element code in terms of sound pressure, directivity etc.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.499-500
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• 2017

This study is about a sound source direction detection system and method using intelligent source collection and analysis. The sound source direction detecting apparatus according to the present invention is equipped with four microphone sensors and calculates a time difference using TDOA (Time Delay of Arrival) technique for a plurality of acoustic signals generated from a sound source, And a sound source detection and analysis algorithm for estimating the direction of the sound source.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.6
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• pp.415-422
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• 2003

In an apartment buildings, the floor Impact sound from upstairs has been regarded as a main source of noise causing discontentment among occupants. To set the optimum design for sound insulation, it is necessary to suggest the useful tools or technique that predict the floor impact sound. The purpose of this study is to suggest the supplementary formula(equation) and constant k considering vibration transmissibility in order to predict more precisely heavy floor impact sound by Impedance Method that have been briskly studied in Japan from comparing the measured values with the predicted values. The analyzed results had showed that if the damping material was glass wool or rubber, k=5 was proper and if the damping material was polystyrene foam, k>5 was desirable.

• Journal of East-Asian Urban History
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• v.2 no.2
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• pp.201-234
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• 2020

In recent years, the studies on the student movement in Republican China have been more accurate. However, some areas still remain uncovered, such as the technology of student movement. In this paper, the author focuses on how students utilize sound tools in their movements, especially in public meetings. During the May 4^th Movement and the 1920s, Chinese students mainly used speaking trumpets without electricity. In the 1930s, electric tools began to appear in student movement for sound propagation. In the student movement of postwar China, students of various political positions could make a use of loudspeaker, wired broadcasting, and megaphone or other equipments. The battle of sound had been part of the Chinese civil war. In general, sound tools had taken an important role in the history of student radicalism.