• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.593-594
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• 2023

본 논문에서는 지향성 스피커를 활용한 APP 기반의 보급형 조류 제어 시스템을 제안한다. 농가에서는 유해조류 퇴치를 위해 그물 설치, 소음 방출, 천적 모형 설치, 화학 약품 사용 등 다양한 방법으로 피해를 줄이고자 하는 노력을 하고 있지만 과다비용과 생활에 피해를 주는 소음 발생 등으로 인해 효과를 볼 수 없는 문제를 가진다. 또한, 무지향성 스피커의 파형특성상 음원 발생기 주변에 불필요한 소음을 농가에 방출하게 되어 소음공해의 피해를 주는 경향을 보인다. 본 연구에서는 지향성 스피커를 활용하여 필요한 구역에만 선택적으로 방출 가능하도록 구현하였으며, 음향을 다양한 패턴 방출를 통하여 패턴인지 저하로 인한 문제를 극복하였다.

• Journal of Korea Game Society
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• v.12 no.1
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• pp.103-111
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• 2012

Games in 1970s have used the savings of analog wavelength as in music and the like on hardwares of small cassette, gramophone, and the like. Due to these configuration elements, durability has to be declined so much. In the event of using the music on the video game, more affordable method is to use the computer chip to convert the analog sound into the computer code to convert into the electric wavelength to send to the speaker. The sound effect of the game is generated in this method. The technical limit has been gradually overcome to grant more freedom to the composers and the sound track pre-recorded on the optic disc and the like has emerged. The game developers of today have made several attempts on the technology to produce the game music. This study has contemplated the process of advancement in the change of game music production with the influence on technology and business.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.4
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• pp.285-289
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• 1997

A Held experiment was carried out to confirm the effect of underwater sound on the luring of fish school of rudder fish in a set net at the coast of Cheju Island. The effects of the acoustic emission on the luring of fish school were observed at a cage around a set net fishing ground using a manufactured underwater speaker. Underwater sounds that were emitted for the luring of fish school were the pure sounds of which frequency were 300Hz and 400Hz, engine noise and swimming sound. The results of the observation are as follows : 1. The input and output wave forms of a manufactured underwater speaker in water tank were similar to those in measurement frequencies. The result of the observation indicated that it could be used for the purpose of the sound emission in measurement frequencies. 2. The effect of the emitted pure sound of 300Hz, 400Hz was remarkable for the luring of fish school in 2 minutes after the sound emission. The reaction of fish school was more sensitive to the pure sound of 400Hz than 300Hz. 3. The effect of the emitted engine noise was more remarkable than that of the pure sound for 3 minute continuously. On the feeding sound, fish formed a shoal and swimmed, but didn't gather around the underwater speaker. 4. The feeding and swimming sound spectra on rudder Hsh showed similar sound pressure distribution each other, they appeared low sound pressure in frequencies of 200-600Hz.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.449-454
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• 1998

전립선 비대증 및 각종 고형암 조직을 제거하기 위해 이용되는 고강도 집속형 초음파 시스템은 초음파의 조직에 대한 열 효과를 이용한다. 이 경우 수MPa의 고 압력 초음파를 사용하기 때문에 수술시 초음파에 의한 조직내의 공동 현상이 수반되고 이로 인해 초음파의 집속 효과가 감소하게 된다. 본 논문에서는 초음파 공동 현상을 억제하기 위하여 초음파의 주파수 특성을 고려하였다. 초음파의 크기는 일정하게 유지하면서 증가하는 주파수로 변조된 초음파와 비선형 고저파 (nonlinear harmonics) 성분을 포함한 왜곡된 초음파에 대한 기포의 반응을 Gilmore 기포 모델을 이용하여 관찰하였다. 초음파의 주파수 변조는 10 $\mu\textrm{s}$ 동안 초기 주파수 1 MHz부터 시작하여 7 MHz까지 선형적으로 증가하도록 하였다. 파형을 왜곡시키는 고저파 성분의 크기는 주파수에 역 비례 하도록 하였다. 초음파의 기본 주파수는 1 MHz로 하였고, 압력은 0.1 MPa과 1 MPa의 두 경우를 고려하였다. 초기 기포의 반경은 1 $\mu\textrm{m}$으로 하였고, 기포 주위의 유체는 물로 가정하였다. 시뮬레이션 결과로부터, 주파수를 변조시키거나 파형을 왜곡시킨 초음파에 대한 기포의 진동은, 동일한 압력의 정현파에 대한 경우 보다 작은 것으로 나타났다. 주파수 변조된 초음파에 반응한 기포의 진동은 압력이 낮을 때 (0.1 MPa), 변조된 주파수가 기포의 공진 주파수인 3 MHz 부근에서 최대치를 보이다가 이후 급격히 감소하는 경향을 보였다. 반면, 압력이 높아지면 (1 MPa) 기포의 진동은 주파수의 증가와 함께 감소하다가 3 MHz 이상으로 변조 될 경우, 유의한 변화를 보이지 않는 것으로 나타났다. 이 결과는 초음파의 적절한 주파수 성분 조절로 초음파 공동 현상을 일정 수준 억제할 수 있음을 시사한다. 고려가 수반되어야 할 것으로 보인다. 다음 내용을 정리해 보고자 한다.리해 보고자 한다.rc$ 구입할 때 중점적으로 살펴보는 사항은 신선도와 순수재래종 여부, 위생상태였다. 한편 소비자가 언제나 구입할 수 없다는 의견이 85.2%나 되어 원활한 공급과 시장조성이 아직 정착되지 않고 있었다. $\bigcirc$ 현재 유통되고 있는 재래종닭은 소비자 대부분이 잡종으로 인식하고 있었으며, 재래종과 일반육계와의 구별은 깃털색, 피부색, 정강이색등 외관상으로 구별하고 있었다. 체중에 대한 반응은 너무 작다는 의견이었고, 식품으로의 인식도는 비교적 고급식품으로 인식하고 있다. $\bigcirc$ 재래종닭고기의 브랜드화에 대한 견해는 젊고 소득이 높은 계층에서 브랜드화의 필요성을 강조하고 있다. $\bigcirc$ 재래종달걀의 소비형태는 대부분의 소비자가 좋아하였으나 아직 먹어보지 못한 응답자가 많았다. 재래종달걀의 맛에 대해서는 고소하고 독특하여 차별성을 느끼고 있었다. $\bigcirc$ 재래종달걀의 구입장소는 계란판매점(축협.농협), 슈퍼, 백화점, 재래닭 사육 농장등 다양하였으며 포장단위는 10개를 가장 선호하였고, 포장재료는 종이, 플라스틱, 짚의 순으로 좋아하였다. $\bigcirc$ 달걀의 가격은 200원정도를 적정하다고 하였으며, 크기는 (평균 52g)는 가장 적당하다고 인식하고 있으며, 난각색은 대부분의 응답자가 갈색을 선호하였다. $\bigcirc$ 재래종달걀의 구입시 애로사항은 믿을수 없고, 구입장소를 몰라서, 값이 싸다 등이었고, 앞으로 신뢰할 수 있고 위생적인 생산 및 유통체계가 확립될 경우 더 많이 소비하겠다는 의견이었다. $\bigcirc$ 재래닭 판매업소(식당)의 판매형태는 66.7%인 대부분

• The Journal of the Acoustical Society of Korea
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• v.18 no.5
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• pp.68-77
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• 1999

The paper looked into the effects of the spectral properties (waveform) of the high intensity focused ultrasound on suppression of the ultrasonic cavitation. Three different types of ultrasound were considered in the study, which were sinusoidal (1 MHz, 5 MPa), frequency modulated (from 1 MHz to 6 MHz for 10 ㎲, 5 MPa), asymmetrically shocked (fundamental frequency 1 MHz, peak positive pressure 12 MPa, peak negative pressure -4 MPa). The temporal response of an air bubble in water initially 1 ㎛ in radius to each type of the ultrasound was predicted using Gilmore bubble dynamic model and Church's rectified gas diffusion equation. It was shown that the radially pulsating amplitude of the bubble was greatly reduced for the frequency modulated wave and was little decreased for the shock wave, compared to the case that the bubble was exposed to the sinusoidal wave. It is interesting that the bubble response to the frequency modulated wave remains similar when the frequency component of the modulated ultrasound is beyond the bubble resonant frequency 3 MHz. This implies that, although the ultrasound is modulated up to 3MHz rather than up to the present 6 MHz, it is likely to produce similar cavitation suppression effects. In practice, it means that a typical narrow band ultrasonic transducer can be taken to generate an appropriate frequency modulated ultrasound to reduce cavitation activity. The present study indicates that ultrasonic cavitation may be suppressed to some extent by a proper spectral modification of high intensity ultrasound.

• The Journal of the Acoustical Society of Korea
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• v.39 no.5
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• pp.441-446
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• 2020

In this paper, we propose the α-Feature Map Scaling (α-FMS) method which extends the FMS method that was designed to enhance the discriminative power of feature maps of deep neural networks in Speaker Verification (SV) systems. The FMS derives a scale vector from a feature map and then adds or multiplies them to the features, or sequentially apply both operations. However, the FMS method not only uses an identical scale vector for both addition and multiplication, but also has a limitation that it can only add a value between zero and one in case of addition. In this study, to overcome these limitations, we propose α-FMS to add a trainable parameter α to the feature map element-wise, and then multiply a scale vector. We compare the performance of the two methods: the one where α is a scalar, and the other where it is a vector. Both α-FMS methods are applied after each residual block of the deep neural network. The proposed system using the α-FMS methods are trained using the RawNet2 and tested using the VoxCeleb1 evaluation set. The result demonstrates an equal error rate of 2.47 % and 2.31 % for the two α-FMS methods respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.1
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• pp.1-12
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• 2013

Acoustic backscatter profiles were measured by Eco-sounder along an east-west section in the mid-eastern Yellow Sea and at an anchoring station in the low salinity region off the Keum River estuary in September 2012, with observing physical water property structure by CTD. Tidal front was established around the sand ridge developed in 50 m depth region. Internal waves measured by Eco-sounder during low tide period in the eastern side of the sand ridge were nonlinear depression waves with wave height of 15 m and mean wavelength of 500 m. These waves were interpreted into tidal internal waves that were produced by tidal current flowing over the sand ridge to the southeast. When weakly non-linear soliton model was applied, propagation speed and period of these internal depression wave were 50 m/s and 16~18 min. Red tides by Dinoflagelates Cochlodinium were observed in the sea surface where strong acoustic scattering layer was raised up to 7 m. Hourly CTD profiles taken at the anchoring station off the Keum River estuary showed the halocline depth change by tidal current and land-sea breeze. When tidal current flowed strongly to the northeast during flood period and land-breeze of 7 m/s blew to the west, the halocline was temporally raised up as much as 2 m and acoustic profile images showed a complex structure in the surface layer within 5-m depth: in tens of seconds the declined acoustic structure of strong and weak scattering signals alternatively appeared with entrainment and intrusion shape. These acoustic profile structures in the surface mixed layer were observed for the first time in the coastal sea of the mid-eastern Yellow Sea. The acoustic profile images and turbidity data suggest that relatively transparent low-layer water be intruded or entrained into the turbid upper-layer water by vertical shear between flood current and land breeze-induced surface current.

• The Journal of the Acoustical Society of Korea
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• v.31 no.7
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• pp.427-434
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• 2012

The overlap-add technique based on waveform similarity (WSOLA) method is known to be an efficient high-quality algorithm for time scaling of speech signal. The computational load of WSOLA is concentrated on the repeated normalized cross-correlation (NCC) calculation to evaluate the similarity between two signal waveforms. To reduce the computational complexity of WSOLA, this paper proposes a fast NCC computation method, in which NCC is obtained through pre-calculated sum tables to eliminate redundancy of repeated NCC calculations in the adjacent regions. While the denominator part of NCC has much redundancy irrespective of the time-scale factor, the numerator part of NCC has less redundancy and the amount of redundancy is dependent on both the time-scale factor and optimal shift value, thereby requiring more sophisticated algorithm for fast computation. The simulation results show that the proposed method reduces about 40%, 47% and 52% of the WSOLA execution time for the time-scale compression, 2 and 3 times time-scale expansions, respectively, while maintaining exactly the same speech quality of the conventional WSOLA.

• The Journal of the Acoustical Society of Korea
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• v.33 no.4
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• pp.262-267
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• 2014

Recently, long pulses are transmitted for target detection in active sonar application. Matched filtering implemented by simple convolution algorithm, requires massive computational power for long replica. The computational loads are reduced significantly by implementing the convolution in the frequency domain with overlap add method, but the performance degrades for specified input/output system delay which constrains the size of FFT function. For performance improvement, the replica could be partitioned into uniform blocks (FDL) by re-using IFFT operations, or variable blocks of increasing length (MC) by using the largest possible blocks to calculate the convolution. In this paper, by combining the strong points of the two methods, we propose a new filter partition structure that allows for further optimization of the previous two methods.

• The Journal of the Acoustical Society of Korea
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• v.36 no.5
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• pp.293-299
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• 2017

Small unmanned platforms maneuvering underwater are the key naval future forces, utilized as the asymmetric power in war. As a method of detecting and identifying such platforms, we introduce a property estimation technique based on an iterative numerical analysis. The property estimation technique can estimate not only the position of a target but also its physical properties. Moreover, it will have a potential in detecting and classifying still target or multiple targets. In this study, we have conducted the property estimation of an small underwater target using the data acquired from the lake experiment. As a result, it shows that the properties of a small platform may be roughly estimated from the in site data even using one channel.