• Korean Journal of Optics and Photonics
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• v.32 no.3
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• pp.108-113
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• 2021

We propose and experimentally demonstrate a method of remote sound extraction using laser Doppler interferometry. The output frequency of a laser Doppler interferometer changes to be the same as the frequency of the acoustic wave from than object vibrated by the sound due to the Doppler effect. Based on this phenomenon, we measure the vibrational frequency of a remote target affected by a sound wave in real time, via laser Doppler interferometry. We track the peak frequency of the interferometer's output via appropriate signal processing, which confirms that the characteristics of the so detected wave are the same as that of the original sound source. We also confirm that the same method can retrieve the sound waves not only from remote sources of single tones, but from those of any sound.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.01a
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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.

• River and Culture
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• v.5 no.4
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• pp.92-96
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• 2009

이번 호에서는 낙후된 수생태복원기술을 21세기 녹색성장사업으로 육성하며, 이를 통하여 수생태계의 건강성을 회복하고 국민의 삶의 질 향상에 기여함을 목표로 하고 있는 '수생태복원사업단'을 소개하는 글로 구성하였습니다.

• The Journal of the Acoustical Society of Korea
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• v.28 no.4
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• pp.343-355
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• 2009

In order to restore the identity of sound environment and expand the sound culture of a region, the purpose of this study are to excavate the resources of soundscape and find out the plans for the preservation and promotion of soundscape resources peculiar to the region. For this purpose, this research is conducted through an interview survey of residents and an observation survey using listening walk in Hongdo, one of the southwesten island of Korea. The results of survey confirm that there are so many sounds to hear around Hongdo island, those are, natural sounds such as the song of the birds, the roar of the waves, the whistling sounds, the shriek of the seagulls, and the pebbles sounds washed away by the waves, and artificial sounds such as the steam-whistle signals, the ship's broadcasts, the voice of tourists, the sounds of church bells, lighthouse sirens etc. The results suggest that it is necessary to consider several ways for restoration of an unique soundscape in Hongdo island, those are, improvement for efficient management of a ship's broadcasts in public areas, removal of a ferry in Hongdo swimming beach, management of Dangsanje (a religious service), preservation of a lighthouse siren and a foghorn, restoration and improvement of underground stream, management and control of public fish market, restoration of brooklet, management of cooperative system for a fish market, restoration of PoongO-Gut (a ritual for a large harvest) and a skate festival, management of a Hongdo sports meeting, sound quality modification of a boat whistle, restoration of orientalia such as a funeral bier, ecosystem preservation activity of the shore and ocean, and promotion of amenity for fascination and vitality in a rural community. Also, a sound map is drawn up for many tourists so as to realize the importance of sound environment and identity of soundscape and to gain their experience at first hand in Hongdo island.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.263-266
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• 2002

성덕대왕 신종은 771년도에 성덕대왕의 공적을 기리기 위해 34년간 주조(높이 3.663m, 최대지름 2.227m, 무게 18,900kg)하여 만든 세계적인 문화유산이다. 외형도 미려하지만 종소리는 천, 지, 인을 뒤흔드는 신비감을 갖추고 있다. 에밀레 종소리는 끊어질 듯 이어지는 소리, 애끓는 소리, 심금을 울리는 소리 등의 특징을 갖는데 끊어질듯 이어지는 소리는 맥놀이 현상으로 나타난다. 지금까지 맥놀이 현상의 규명에 대한 많은 연구가 있었다. 여기에는 우리 선조들이 750년경에 과학적 근거를 토대로 하여 응용이 가능하였음을 알 수 있다. 그러나 근래에 와서 웅장하고 신비로운 신금을 울리는 소리가 두드러지게 나오지 않는다. 결론적으로 근래의 낙후된 에밀레 종으로 인해서 변형된 종소리와 예전의 고유한 종소리를 분석하고 우리 민족의 지혜와 숨결이 스며있는 세계적인 문화유산인 에밀레 종소리 복원이 강구되어야 하며 과학적이고 체계적인 관리가 요구되어야 한다.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.3
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• pp.145-150
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• 2019

We develop the system realization of whale sound reconstruction by inverse MFCC algorithm with the weighted L2-norm minimization techniques. The output products from this research will contribute to the whale tourism and multimedia content industry by combining whale sound contents with the prototype of 3D printing. First of all, we develop the softwares for generating whale sounds and install them into Raspberry Pi hardware and fasten them inside a 3D printed whale. The languages used in the development of this system are the C++ for whale-sounding classification, MATLAB and Python for whale-sounding playback algorithm, and Rhino 6 for 3D printing.

• Korean Journal of Environment and Ecology
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• v.36 no.3
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• pp.350-357
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• 2022

A national park is a place to conserve natural resources and visitors to experience nature, and thus, it is necessary to identify the noise distribution characteristic in the national park and preserve and restore the soundscape. However, most national parks in Korea are exposed to noise, leading to negative perceptions of the national park's soundscape and affecting the ecosystem. Many national parks in other countries have investigated the ecosystem impacts caused by noise and have performed various management to reduce the noise. However, in Korea, there is still a lack of awareness of the effect on the ecosystem, overlooking the need for soundscape management. Therefore, in this study, we developed a noise map of Mudeungsan National Park to investigate the quantitative impact of noise on visitors and the ecosystem. Also, we measured the trail's soundscape to describe a sound grade classification, and the soundscape of main spots in the park was recorded for a year and then analyzed. Finally, the sound resource distribution map was described, which can be used as preliminary data to determine the national park's sound distribution characteristics and manage the soundscape.

• Korean Journal of Weed Science
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• v.18 no.3
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• pp.262-267
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• 1998

We evaluated Ambrosia artemisiifolia var. elatior, Ambrosia trifida, Rumex crispus which were reported to have good phytoremediatibility in different concentrations of Cu and Cd. Different growth responses were found in different heavy metal concentrations. Good growth rate for A. trifida and A. artemisiifolia var. elatior in Cu and Cd treatments and poor growth for R. crispus in Cd treatment were found. Although growth was retared in all tested weeds up to 200ppm for Cu and 50ppm for Cd, the high amount of heavy metal uptake indicated that these weeds could be used as phytoremediation. The choice of proper plant for bioremediation in different sources of heavy metal pollution seems important. In this regard, A. trifida which showed little variation in Cu accumulation in shoot under different Cu concentrations could be used for phytoremediation and phytostabilization.

• Korean Architects
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• no.5 s.409
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• pp.72-77
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• 2003

도시를 온통 콘크리트로 막고 덮던 개발 전성시대의 전환점에서, 우리는 생태 도시환경의 질적 가치에 대해 생각해야 하는 새로운 시대를 맞이하고 있다. 성장과 개발이 곧 행복의 보증수표임을 믿고 달려온 어느 지점에서 그 신기루를 허무하게 체험하며, 유토피아는 현실의 환경 가운데에서만 창조될 수 있음을 고통스럽게 인식하게 된 것이다. 그렇게 개발독재 시대에 복개되었던 청계천과 고가도로는 이 시대의 새로운 화두로 등장하게 되었다. 시민단체를 중심으로 일던 청계천 복원운동은 급기야 서울시장 선거의 첫 번째 정책공방거리로 부상하고, 건설인 출신의 시장 당선과 더불어 2005년을 목표로 일사 천리한 건설을 예정하고 있다. 그러나 일각에서는 걱정의 소리도 만만치 않다. 이미 여러차례에 걸쳐 지적된 기술적, 경제적 문제들 외에도, 이 시대 도시환경의 새로운 패러다임을 짜게 될 사업이기에 심사숙고를 필요로 한다는 것이다. 이러한 여론과는 아랑곳 않고, 서울시는 사뭇 독선적이고 저돌적인 추진을 진행시키고 있다. 과연 청계천 복원사업은 어떻게 이루어져야 하는가? 비록 역사와 문화를 달리하지만, 1970년대에 있었던 프랑스 파리의 레알(Les Halles) 시장 재개발 사업은 우리의 작금의 현실과 관련하여 여러 가지 면에서 공통점을 공유하고 있으며, 교훈으로 삼기에 시사하는 바가 크다.

• Journal of the Korea Society of Computer and Information
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• v.27 no.11
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• pp.81-87
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• 2022

In this paper, we propose diffraction-based sound control method to improve sound immersion in a virtual environment. The proposed technique can express the wave and flow of sound in a physical environment and a pattern similar to diffraction in real-time. Our approach determines whether there is an obstacle from the location of the sound source and then calculates the position of the new sound reflected and diffracted by the obstacle. Based on ray tracing, it determines whether or not it collides with an obstacle, and predicts the sound level of the agent behind the obstacle by using the vector reflected and refraction by the collision. In this process, the sound attenuation according to the distance/material is modeled by attenuating the size of the sound according to the number of reflected/refracted rays. As a result, the diffraction pattern expressed in the physics-based approach was expressed in real time, and it shows that the diffraction pattern also changes as the position of the obstacle is changed, thereby showing the result of naturally spreading the size of the sound. The proposed method restores the diffusion and diffraction characteristics of sound expressed in real life almost similarly.