• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2021년도 제63차 동계학술대회논문집 29권1호
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• pp.269-271
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• 2021

본 논문에서는 실제 현실에서 표현되는 소리의 특징인 파동(Sound wave)과 흐름(Sound flow) 그리고 회절(Diffraction of sound)을 가상환경에서 실시간으로 표현할 수 있는 방법을 제안한다. 우리의 접근 방식은 소리가 재생되는 위치로부터 장애물 여부를 판단하고, 장애물이 존재할 시, 장애물로 인해 반사와 회절된 새로운 소리 위치를 계산한다. 이 과정에서 레이트레이싱 기반으로 장애물과의 충돌 여부를 판단하고, 충돌에 의해 굴절된 벡터를 이용하여 장애물 너머에서 들리는 소리의 크기를 계산하며, 충돌된 레이의 개수에 따라 소리의 크기를 감쇠시킨다. 본 논문에서 제안하는 방법을 이용한 소리의 회절은 물리 기반 접근법에서 나타나는 회절 형태를 실시간으로 표현했으며, 장애물에 따라서 회절 패턴이 변경되고, 이에 따라 소리의 크기가 자연스럽게 조절되는 결과를 보여준다. 이 같은 실험은 실제 현실에서 나타나는 소리의 퍼짐과 같은 특징을 거의 유사하게 복원해냈다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.591-594
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• 2004

The directivity of the sound pressure increases the sensitivity of the incoming sound from specific directions. The directivity measurement of the sound pressure is usually done in an anechoic room using a steping motor. In this paper a replaceable anechoic chamber was designed for the acoustic directivity pattern measurement. Electrical equipments were interfaced with a PC for experiment automatic control. Some comparative results are shown in the result.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2003년도 제20회 춘계학술대회 논문집
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• pp.67-71
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• 2003

The propagation characteristics of the impulse wave discharged from the exit of a perforated pipe is investigated through a simple shock tube facility. The pressure histories and directivities of the impulse wave propagating outside from the exit of pipe with several different configurations are analyzed for the range of the incident weak shock wave Mach number between 1.02 and 1.2. In the shock tube experiments, the impulse wave are visualized by a Schlieren optical system for the purpose of understanding its propagation characteristics. The experimental results show that for the near sound field the impulse noise strongly propagates toward to the pipe axis, but for the far sound field the impulse noise uniformly propagates toward to the omnidirections, indicating that the directivity pattern is almost same regardless of the pipe type. Especially, it is shown that the perforated pipe has a little performance to reduce the impulse noise only for the near sound field

• 한국소음진동공학회논문집
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• 제21권4호
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• pp.307-314
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• 2011

This study was focused on the influence of soundscape provided to the interior landscape on the improvement of occupants' sound environment. When soundscape was provided to occupants together with the interior landscape rather than simply providing interior landscape, the occupants' satisfaction seemed to be improved. The most preferred sound source among the three sound sources was considered as the sound of the grasshopper. When both of the interior landscape and the landscape substances was provided, the adjectives with the average difference of more than 1 are "Vicissitudinous", "Elegant" and "Cheerful". When the interior landscape and the sound source were provided, such adjectives as "Vicissitudinous", "Complex" and "Cheerful" are extracted. When all the variables were provided, such adjectives as "Vicissitudinous", "Abundant" and "Cheerful" seem to show the difference of more than 1. Regarding "Vicissitudinous", it was possible to know that the average difference of more than 1.5 was the biggest. Regarding the relative values of the ${\alpha}$ wave and the ${\beta}$ wave for each part, it seemed that the highest ${\alpha}$ wave was generated on the left parietal lobe of P3, while the lowest ${\beta}$ wave was generated on the left and right frontal lobes of Fp1 and Fp2. According to this study, it was shown that the soundscape and the interior landscape seemed to influence the improvement of the occupants' sound environment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.117-119
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• 2004

In order to successfully exploit underwater resources, the first step would be a marine environmental research and exploration on the seafloor. Traditionally one sets up a long-term underwater experimental unit on the seafloor and retrieves the unit later after a certain period time. Essential to these applications is the reliable teleoperation and telemetering of the unit. This study presents ultrasonic-wave remote control system and an underwater sound recognition algorithm that can identify the sound signal without the influence of disturbances due to underwater environmental changes. The proposed method provides a means suitable for units which require low power dissipation and long-time underwater operation. We demonstrate its ability of securing stability and fast sound recognition through experimental methods.

• International Journal of Aeronautical and Space Sciences
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• 제5권2호
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• pp.18-27
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• 2004

An axisymmetric supersonic jet is simulated at a Mach number 2.1 and a Reynolds numberof 70000 to identify the mechanism of Mach wave generation and radiation from the jet. In orderto provide the near-field radiated sound directly and resolve the large-scale vortices highly.high-resolution essentially non-oscillatory(ENO) scheme, which is one of the ComputationalAeroAcoustics(CAA) techniques, is newly employed. Perfectly expanded supersonic jet is selectedas a target to see pure shear layer growth and Mach wave radiation without effect of change injet cross section due to expansion or shock wave generated at nozzle exit. The sound field ishighly directional and dominated by Mach waves generated near the end of potential core. Thenear field sound pressure levels as well as the aerodynamic properties of the jet, such asmean-flow parameters are in fare agreement with experimental data.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.2066-2070
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• 2003

This experimental study describes the propagation characteristics and suppression of the impulse noise emitted from the exit of a perforated pipe attached to the open end of a simple shock tube. The experiment is performed through the systematic change of the shock wave Mach number and the geometrical parameters such as the porosity, hole diameter and length of the perforated pipe. The experimental results for the near and far sound field are presented and explained in comparison with those for a straight pipe. The results obtained show that for the near sound field the impulse noise strongly propagates toward to the pipe axis, but for the far sound field the impulse noise uniformly propagates toward to the all directions, indicating that the directivity pattern is almost same regardless of the pipe type. Moreover, the noise reduction performance of perforated pipe depends upon the condition of sound field. For the near sound field the perforated pipe has a little performance to suppress the impulse noise, but for the far sound field the perforated pipe has little performance to suppress the impulse noise.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(5)
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• pp.99-102
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• 2000

This study analyze of reflection wave to Acoustic stimulation on acupoints and contrast parts for objectification of the meridian substance. In order to verify meridian pathway and channel theory of bio-energy in body. It was analyzed response characteristic of reflection waves after acoustic stimulation by sound wave of 5 specific tones. The response characteristics of reflection are measured by the average current magnitude of meridian. The current variation ratio are Live Meridian(gung) 33.2%, Heart Meridian(sang) 30.7%, Kidney Meridian (gak) 33.1%, Spleen Meridian(chi) 33.9%, Lung Meridian (wo) 30.7% compare with contrast parts (non-acupoint and meridian). Therefore meridian is distinguished to non-meridian and 5 vital meridians have relationship with sound wave of 5 specific tones.

• 한국음향학회지
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• 제21권2호
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• pp.110-119
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• 2002

수중퇴적물의 투과음향특성을 실험실 조건에서 고찰하였다. 물로 포화된 입자지름 0.5 mm이하의 모래퇴적물을 (재질의 두께가 1 mm이고 부피가100mm×100m×42m인 아크릴상자 안에) 형성시켜 수중모래퇴적물 시료를 제작하였다. 수중 모래퇴적물 시료의 다공율을 조절할 수 있도록 퇴적물 내부에 내경 3 mm, 길이 42 mm인 원통형 관들을 이용하여 물로 채워진 관을 위치시켜서, 원통다공율이 각각 0 %, 5%, 11%, 18%, 26%인 다섯 개의 수중 모래퇴적물 시료를 만들었다. 수중 모래퇴적물 시료의 음향특성을 다공율과 0.3 MHz에서 4 MHz의 구간에서 주파수의 함수로 분석하였다. 수중 모래퇴적물 시료를 투과한 음향신호는 시료 전체로부터 나온 첫번째파 (first-kind wave)와 관을 통하여 나온 두번째파 (second-kind wave)를 구분하여 관측하였다. 중심주파수 1 MHz에서는 첫번째파가 지배적이었으나 중심주파수 2.25 MHz에서는 두번째파가 지배적이었다. 첫번째파의 경우, 다공율이 증가되면 음압투과계수는 작아지고 음속은 물의 음속에 가깝게 낮아지며, 주파수가 증가되면 투과계수는 점차 작아지나 음속의 변화는 없었다. 두번째파의 경우, 다공율이 커지면 투과계수가 커지고 음속은 변화가 없었으며, 주파수가 증가되어도 투과계수와 음속의 변화는 없었다.

• 식물병연구
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• 제20권1호
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• pp.1-7
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• 2014

Plant growth is considered the sum of cell proliferation and subsequent elongation of the cells. The continuous proliferation and elongation of plant cells are vital to the production of new organs, which have a significant impact on overall plant growth. Accordingly, the relationship between environmental stimuli, such as temperature, light, wind, and sound waves to plant growth is of great interest in studies of plant development. Sound waves can have negative or positive effects on plant growth. In this review paper we have summarized the relationship between sound waves and plant growth response. Sound waves with specific frequencies and intensities can have positive effects on various plant biological indices including seed germination, root elongation, plant height, callus growth, cell cycling, signaling transduction systems, enzymatic and hormonal activities, and gene expression.