• 한국철도학회논문집
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• 제19권3호
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• pp.271-279
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• 2016

팬터그래프의 공력소음은 열차가 고속으로 주행할 때 발생하는 소음의 주요한 원인이다. 본 연구에서는 팬터그래프에 의한 공력소음 기여도를 분석하기 위하여 차세대고속열차(HEMU-430X)를 이용하여 시험을 수행하였다. 실제차량에서의 팬터그래프에 의한 소음의 주파수 특성을 분석하기 위하여, 350km/h와 400km/h 주행 시 전체차량의 음장가시화를 144채널 마이크로폰 어레이를 이용하여 수행하였다. 음장가시화 분석결과 팬터그래프의 소음은 250~400Hz 대역의 저주파 소음이 주로 기여함을 확인하였다. 또한 팬터그래프의 소음 기여도를 분석하기 위하여 팬터그래프의 올림 및 내림 시 소음도 차이를 단일 마이크로폰 시험을 통하여 비교분석하였다. 단일 마이크로폰 시험을 통한 팬터그래프 소음의 주요 주파수 특성은 315~400Hz와 1000~1250Hz 대역임을 확인 하였으며 이는 기존의 연구 결과 및 음장가시화 결과와 잘 일치하였다.

• 농촌계획
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• 제19권2호
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• pp.63-73
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• 2013

This study investigated the elements of soundscape in and around the traditional Korean style housing complex and the standardized Korean style housing complex popularized as farm village by Traditional Korean style housing assistance policy located in the rural area of Jeollanam-do. The purpose of this study is to understand the phenomenon and characteristic differences of the sound environments in various observation points in order to utilize them as the important elements of sound scape to consider for standardized Korean style housing complex development in the future. As a result, the traditional housing in rural area led more positive evaluation of nature sounds than standardized, newly developed Korean style housing complex. In the list of noises in each residential development type, traffic sounds and construction noise were majorly ranked. However, nature sounds had high rate of response in the sounds of introduction request. Additionally, the sounds generated by human activities such as whispering and footsteps were also in the wish list. This may suggests that soundscape design needs to approach in cultural level of a society rather than simple investigation and treatment of individual sounds of natural and artificial.

• 한국항공우주학회지
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• 제37권1호
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• pp.17-27
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• 2009

압축성 영역에서 개발된 2상 유동 RoeM과 AUSMPW+를 전 마하수 영역 해석을 위해 예조건화 하였다. 압축성 영역에서 개발된 풍상차분 수치기법들은 수치점성에서 음속을 포함하는 항들을 갖고 있는데, 이는 비압축성 영역에서 관련 수치점성 크기를 지나치게 크거나 작게 만들어 해의 정확도를 떨어뜨리거나 수치 불안정 현상을 일으킨다. 따라서 예조건화된 시스템 고유값을 수치점성에 고려하여 전 마하수 영역에서 해의 정확성을 확보하였고, 점근 분석을 통해 개발된 수치기법이 비압축 극한 영역에서 보존형 지배방정식과 일관됨을 확인하였다. 수치 예제들을 통해 예조건화된 2상 유동 RoeM과 AUSMPW+가전 마하수 영역에서 합리적인 해를 도출함을 알 수 있었다.

• 한국군사과학기술학회지
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• 제21권4호
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• pp.447-455
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• 2018

If a hidden enemy is shooting, there is a threat against soldiers in recent conflicts. This paper aims to improve the localization of a muzzle using microphone array. Gunshot noise can provide information about the location of muzzle with two signals, the muzzle blast from the gun barrel and the projectile sound from the bullet. Two signals arrive to the microphone array with different arrival time and angle. If the arrival angles of the two signals are estimated, distance between sniper location and the microphone array can be calculated by using geometric principles. This method was established in 2003 by Pare. But this method has a limitation that it cannot calculate the distance when the arrival angles of the two signals are same. Also it has an error when the angle difference of arrival is small. In order to overcome this limitation, a new method is proposed that uses the change of characteristic of the projectile sound with respect to vertical distance from the trajectory. The proposed method estimates the distance correctly when the arrival angle of two signals are same, and when the angle difference between two signals is increased, the estimation error increases with respect to the angle. Therefore these two methods can be selected according to the angle difference between two signals to estimate the distance of the muzzle. Below the threshold of the angle difference, the proposed method can be used to estimate distance with smaller error than the existing method. This was demonstrated by shooting tests using actual sniper rifles.

• 한국멀티미디어학회논문지
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• 제13권7호
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• pp.973-982
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• 2010

본 논문에서는 심음 향상을 위해 단일 채널 적응 잡음 제거기를 제안한다. 청진음은 일상적이거나 응급 상황 시 다양한 소리가 섞여 심음의 판독이 어려운 특징이 있다. 기존의 두 채널의 입력을 가지는 적응 잡음 제거기에서 단일 채널의 구현을 위해 단일 채널로 입력된 청진음은 심음의 특징을 기반을 둔 HS 분석기와 BS-Gate를 제안하여 기준 신호를 생성하였다. 제안한 단일 채널 적응 잡음 제거기는 BIOPAC Systems, Inc의 SS30L과 MP 36을 이용하여 획득한 청진음을 이용하여 실험하였으며, 그 결과 효과적으로 호흡음이 감쇄하여 심음이 향상되는 것을 확인할 수 있었다. 또한 단일 채널을 사용하는 적응 선 스펙트럼 강조기와의 비교 실험을 통해 심박의 변화에도 효과적으로 잡음을 제거하였음을 확인할 수 있었다.

• 한국음향학회지
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• 제37권4호
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• pp.248-255
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• 2018

세단 타입에 비해 해치백 타입의 차량은 실링구조 확보에 어려움이 있기 때문에 후석에서 느껴지는 차폐성능이 열세한 것으로 알려져 있다. 차량의 차폐감 확보를 위해 강건한 실링 시스템과 충분한 흡음/차음 성능이 요구되지만 준중형 이하 세그먼트에서는 원가, 중량의 제약으로 인해 충분한 흡차음 사양 적용에 제한을 받고있어 효율적인 흡차음 사양의 적용이 요구되고 있는 실정이다. 본 연구에서는 정량적인 측정과 비교, 분석이 가능한 파워기반 소음감소(Power Based Noise Reduction, PBNR) 기반의 차음 윈도우 평가를 통해 준중형 해치백 차량의 후석 소음원의 전달 경로를 분석하고 후석 차폐성능 확보를 위한 흡차음 대안을 제시하였다.

• 전자공학회논문지SC
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• 제38권3호
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• pp.47-54
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• 2001

본 논문에서는 경락의 실체를 객관화하기 위한 방법으로서, 경락과 비경락을 음향 자극하고 인체의 임피던스 변화를 분석하였으며, 인체 에너지에 대한 고전 동양의학 이론인 경락순행통로 학설의 타당성을 입증하기 위하여 경락지하수 학설을 제안하였다. 현대의학의 주장과 같이 경락은 그 존재를 증명할 만한 채널이나 파이프 형태의 해부학적 실체를 가지고 있지 않다. 그러나 생체에너지는 인체 안에서 관상구조없이 지하를 흐르는 지하수 흐름과 유사하게 경락을 따라 흐른다. 이러한 모델의 반응특성을 확인하기 위하여, 인체의 경락을 지하수가 흐르는 관로로 보고 지하수를 탐지하는 산업용 음향탐사기법을 적용하기 위하여, 피부와 청각을 구분하여 음향자극하고 경혈과 대조적인 비경혈에서의 인체 임피던스 반응을 분석하였다. 특히 자극 음향과 12경락과의 주파수 상관성을 추출하기 위하여, 5개의 특정 음으로 자극하고 측정전류의 평균치와 변화율을 처리하였다. 분석결과 전류 변화율은 족궐음간경(宮), 수소음심경(商) 30.6%, 족소음신경(角) 33.1%, 족태음비경(徵) 33.9%, 수태음폐경(羽) 30.7%로 대조점과 구별되는 특성을 가지고 있어서, 경락은 비경락과 구별되는 채널 특성을 나타내고 있으며 5개 경락은 5개의 특정 음과 상관성이 있음을 확인하였다.

• Transactions on Electrical and Electronic Materials
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• 제10권6호
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• pp.222-226
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• 2009

The objective of this study is to share multimedia contents included in existing digital devices and to solve the problems of an increase in installation fees and non-environmentally friendly interiors. This study designed a new digital signal transmitter and receiver using power line transmission and HDMI in order to solve the problems in the existing systems. The transmitter and receiver designed in this study used an AD9867BCPZ PLC chip in which the transmission came from digital signals originating in a PC, and the system architecture was configured so that the outputs signals were connected to a TV from the receiver. The experiment was implemented by adding a Video Test Generator, a USBPre external sound card, and Smaart Live 6 for analyzing the characteristics of the configured system. In the video test results, it was verified that communication was actively implemented, and the image quality showed a constant level from the measurement of the captured video. In the case of the sound, it was verified that more than 90% of the sound signals were normally transmitted and received from the examination of their phases and magnitudes. Thus, the performance of the system designed in this study was verified, which leads to the resolution of some of the problems found in current digital devices.

• 한국음향학회지
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• 제22권5호
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• pp.388-402
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• 2003

In this paper, we carried out the word, 4 continuous digits. continuous, and task-independent word recognition experiments to verify the effectiveness of the re-defined phoneme-likely units (PLUs) for the phonetic decision tree based HM-Net (Hidden Markov Network) context-dependent (CD) acoustic modeling in Korean appropriately. In case of the 48 PLUs, the phonemes /ㅂ/, /ㄷ/, /ㄱ/ are separated by initial sound, medial vowel, final consonant, and the consonants /ㄹ/, /ㅈ/, /ㅎ/ are also separated by initial sound, final consonant according to the position of syllable, word, and sentence, respectively. In this paper. therefore, we re-define the 39 PLUs by unifying the one phoneme in the separated initial sound, medial vowel, and final consonant of the 48 PLUs to construct the CD acoustic models effectively. Through the experimental results using the re-defined 39 PLUs, in word recognition experiments with the context-independent (CI) acoustic models, the 48 PLUs has an average of 7.06%, higher recognition accuracy than the 39 PLUs used. But in the speaker-independent word recognition experiments with the CD acoustic models, the 39 PLUs has an average of 0.61% better recognition accuracy than the 48 PLUs used. In the 4 continuous digits recognition experiments with the liaison phenomena. the 39 PLUs has also an average of 6.55% higher recognition accuracy. And then, in continuous speech recognition experiments, the 39 PLUs has an average of 15.08% better recognition accuracy than the 48 PLUs used too. Finally, though the 48, 39 PLUs have the lower recognition accuracy, the 39 PLUs has an average of 1.17% higher recognition characteristic than the 48 PLUs used in the task-independent word recognition experiments according to the unknown contextual factor. Through the above experiments, we verified the effectiveness of the re-defined 39 PLUs compared to the 48PLUs to construct the CD acoustic models in this paper.

• 한국실내디자인학회논문집
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• 제24권1호
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• pp.178-188
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• 2015

This study has the main objective of being of help as a reference data for the application of the finishing materials when designing the interior of the chapel of the church space through analysis of the finishing materials against the chapels of church space which has complex function. As precedent studies for this, the composition of the function and concept of the church space was surveyed and the complex function of the church space was surveyed. The theoretical surveyed was performed according to the casual composition, behavior of the community and role and location of the duties of the church members. The case objects were 10 chapels constructed by 5 professional interior design companies. The content of the analysis was the finishing materials in the chapels and their application characteristics. The detailed considerations to be referred to when designing the interior of the chapels of church space in the future were proposed. The analysis result of the application of the finishing materials according to the locational function of the chapels of church space can be explained as follows. First, the platform area was the characteristic of applying finishing materials which induce visual immersion. As for the floor materials in the platform, in order to minimize the floor sound and vibration phenomenon occurring during movements, noise insulation and dust protection rubber sheet was place and on top of it the floor or the carpet was placed. Second, the Choir area had the difficult problem of having to consider the appropriate sound absorption occurring due to the proliferation of sound and performance of classical instruments at the same time. However, in the case, this problem was solved through the sculptures of convex shape. Third, since the scheelite is a space where many people move around, the finishing material which absorbs sound was mainly used. Fourth, the entrance area was composed of thick wall materials compared to other walls, and the sound absorption character was most significantly considered when applying the finishing material. Fifth, the broadcasting room was composed either in independent type or an open type and performed its function and the main finishing materials was transparent glass which was highest use frequency.