• Journal of the Korea Society of Computer and Information
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• v.19 no.2
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• pp.57-65
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• 2014

The role of sound in producing 3D animation clip is one of the important factor to maximize the immersive effects of the scene. Especially interaction between video and sound makes the scene expressions more apparent, which is diversely applied in video production. One of these interaction techniques, the out-focussing technique is frequently used in both real video and 3D animation field. But in 3D animation, out-focussing is not easily implemented as in music videos or explosion scenes in real video shots. This paper analyzes the sound data to synchronize the depth of field with it. The novel out-focussing technique is proposed, where the object's field of depth is controlled by beat rhythm in the sound data.

• Economic and Environmental Geology
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• v.43 no.4
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• pp.349-358
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• 2010

For imaging complex subsurface structures such as salt dome, faults, thrust belt, and folds, seismic prestack reverse-time migration in depth domain is widely used, which is performed by the cross-correlation of shot-domain wavefield extrapolation with receiver-domain wavefield extrapolation. We apply the prestack reverse-time migration, which had been developed at KIGAM, to the seismic field data set of Block 5 in Jeju basin of Korea continental shelf in order to improve subsurface syncline stratigraphy image of the deep structures under the shot point 8km at the surface. We performed basic data processing for improving S/N ratio in the shot gathers, and constructed a velocity model from stack velocity which was calculated by the iterative velocity spectrum. The syncline structure of the stack image appears as disconnected interfaces due to the diffractions, but the result of the prestack migration shows that the syncline image is improved as seismic energy is concentrated on the geological interfaces.

• The Journal of the Acoustical Society of Korea
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• v.43 no.3
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• pp.361-367
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• 2024

Ultrasound in the air is widely used in industry as a measurement technique to prevent abnormalities in the machinery. Recently, the use of airborne ultrasound imaging techniques, which can find the location of abnormalities using an array transducers, is increasing. A beamforming method that uses the phase difference for each sensor is used to visualize the location of the ultrasonic sound source. We exploit a random sparse ultrasonic array and obtain beamforming power distribution on the source in a certain distance away from the array. Conventional beamforming methods inevitably have limited spatial resolution depending on the number of sensors used and the aperture size. A high-resolution ultrasound imaging technique was implemented by applying functional beamforming as a method to overcome the geometric constraints of the array. The functional beamforming method can be expressed as a generalized beam forming method mathematically, and has the advantage of being able to obtain high-resolution imaging by reducing main-lobe width and side lobes. As a result of observation through computer simulation, it was verified that the resolution of the ultrasonic source in the air was successfully increased by functional beamforming using the ultrasonic sparse array.

• Journal of KSNVE
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• v.7 no.2
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• pp.255-260
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• 1997

This paper describes 3-dimensional volume array of 4 microphones including a reference microphone which is capable of imaging wideband noise source position in 2-dimensional image plane. The cross correlation function and corresponding imaging function between a reference microphone and other microphone, are derived as a function of noise source position. The magnitude of the imaging function gives noise source mapping in image plane. Since the image plane is selective from a rectangular and a cylindrical plane, noise source position information such as range and bearing relative to the array is identified very much easily. Simulation results for typical source configurations confirms the applicability of the proposed array in noise control field.

• Geophysics and Geophysical Exploration
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• v.9 no.1
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• pp.102-107
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• 2006

Recently, rapid developments in computer hardware have enabled reverse-time migration to be applied to various production imaging problems. As a wave-equation technique using the two-way wave equation, reverse-time migration can handle not only multi-path arrivals but also steep dips and overturned reflections. However, reverse-time migration causes unwanted artefacts, which arise from the two-way characteristics of the hyperbolic wave equation. Zero-lag cross correlation with diving waves, head waves and back-scattered waves result in spurious artefacts. These strong artefacts have the common feature that the correlating forward and backward wavefields propagate in almost the opposite direction to each other at each correlation point. This is because the ray paths of the forward and backward wavefields are almost identical. In this paper, we present several tactics to avoid artefacts in shot-domain reverse-time migration. Simple muting of a shot gather before migration, or wavefront migration which performs correlation only within a time window following first arriving travel times, are useful in suppressing artefacts. Calculating the wave propagation direction from the Poynting vector gives rise to a new imaging condition, which can eliminate strong artefacts and can produce common image gathers in the reflection angle domain.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06e
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• pp.243-246
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• 1998

집속음장의 고조파성분을 이용한 초음파영상의 특성을 해석하기 위해 집속된 가우스 음원에 직선 edge를 초점면 및 초점면의 전, 후방에 삽입하여 edge의 후방에서 생성되는 음장을 조사하였다. 계산에서는 그린함수의 간단화를 위해 Fresnel근사를 이용하였고, 실험에서는 성형전극을 형성시킨 1.9MHz 요면진동자에 의한 가우스분포의 음장을 갖는 초음파빔에 수직하게 edge를 삽입시켰다. 음장의 이론해석 및 실험결과, 초점면의 제2고조파의 빔형상을 제외하고는 계산치와 실험치가 잘 일치하고 있으며, 제2고조파의 공간 분해능이 기본파에 비해 높음을 알았다.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06d
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• pp.13-17
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• 1998

집속음장이 고조파성분을 이용한 초음파영상의 특성을 해석하는 초기단계로서 음축에 수직하게 놓인 강체판의 직선 edge가 집속 가우스빔을 회절시킨다고 가정하고, edge의 전후에서 발생하는 제 2고조파를 고려해서 회절음장을 해석하였다. 계산에서는 그린함수의 간단화를 위해 , Fresnel 근사를 이용하였고 실험에서는 성형전극을 형성시킨 요면 압전진동자에 의한 1.9MHz 집속가우스음원에 의해 만들어지는 초음파 빔에 수직하게 edge을 삽입시켰다. 회절 edge 후방에서 음장을 관측한 결과, 제 2고조파의 빔형상을 제외하고는 계산치와 실험치가 잘 일치하고 있다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.6_spc
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• pp.687-696
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• 2016

A series of process to design an acoustic lens for underwater imaging is reviewed and the method to evaluate characteristics of the lens is investigated. If the target specification of lens is given, the design process consists of the material selection, evaluation of its properties, lens geometry design, prediction of lens characteristics, manufacturing, and evaluation by measurement. In this study, an actual acoustical lens is made by cutting polymethylpentene block. The characteristics of lens are predicted by the hybrid method, combination of ray tracing and Rayleigh integral. For the direct comparison between the prediction and measurement results, a simulation method based on the equivalent source method is suggested to reflect the actual radiation pattern of transducer used for measurements. Finally, the measurement is conducted in a small water tank to observe the actual characteristics of the manufactured lens.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.430-435
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• 2008

Thanks to the development of IT technology, there have been developed a variety of types of portable music players. IT technology didn't stop there, however. It has gone to developing GUIs (Graphic User Interfaces) to deliver more information to the user. As the function of GUIs has become important, the music players are being required to show characteristics of the sounds they output visually beyond just delivering the sounds through analyzing the information that the sounds contain. To visualize the information of sounds, that is to say, has become substantial. In this process, sound graphic equalizers have been developed in order. The object of this study is to produce a new sound graphic equalizer with new forms of expressing visual images of sounds besides the bar graphs, in which user feedback is possible. This study has devised a new sound visualization form in visually expressing the information of sounds by analyzing their characteristics. This new sound visualization provides a sound graphic equalizer with which the user can select images for the information of the sounds s/he listens. This study suggests a new alternative GUI with which the user can change the form of the outputted images in realtime as communicating with the player.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.07a
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• pp.47-50
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• 2017

PC 혹은 모바일 환경이 점점 발전됨에 따라 사용자들은 자신의 목적에 맞는 다양한 콘텐츠들을 쉽게 이용하고 있다. 사용자는 정상적인 콘텐츠를 이용할 경우 콘텐츠가 가지고 있는 태그정보를 통해 콘텐츠의 내용을 식별하여 사용한다. 하지만 올바른 태그정보가 들어있지 않은 콘텐츠의 경우 사용자는 잘못 입력된 태그정보로 인해 콘텐츠를 식별하는 과정에서 어려움을 겪을 수 있는 문제점을 가지고 있다. 본 논문에서는 사용자가 가지고 있는 콘텐츠에 접근하여 스마트폰 혹은 PC에 저장되어있는 다양한 콘텐츠들을 유튜브 API를 통해 유튜브 플랫폼에 존재하는 영상들과 매칭 시키고, 매칭 시킨 영상들을 사용자 계정에 동기화시키는 시스템을 제안한다.