• Journal of the Korean GEO-environmental Society
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• v.11 no.6
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• pp.21-29
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• 2010

In this study, a new noise & vibration-free screw concrete pile method that was expected environmentally friendly method was introduced, also the numerical analyses of a conventional PHC pile and a new screw concrete pile were done. As a result, the bearing capacity behavior and the settlement behavior of 2 kinds of concrete pile were analyzed and compared.

• The Journal of the Acoustical Society of Korea
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• v.33 no.5
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• pp.316-325
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• 2014

The basic unit of school is a classroom and the aural environment of the classrooms is essential factor for education purposes. Therefore, many efforts have been undertaken for enhancing the acoustical performance of the classrooms in many countries. As a result, acoustic criteria including reverberation time and background noise level have been established in US and UK for school classrooms depending on the usage and size of the rooms. However, in Korea, there has been little researches concerning the room acoustical investigations of the classrooms. The present study investigates the current situation of the aural environment of the 15 classrooms in Korea including elementary, middle and high schools. The acoustic criteria measured include RT, $D_{50}$, STI, SNR and background noise level. As the results, it was found that the background noise levels of the schools adjacent to roads exceed the US and UK standard of 35 dB(A). Also, most schools have so low SNR that they may be interfered by noise, which may affect speech transmission. It was also revealed that some schools have longer RT than the US standard of 0.6 s, but they all have high speech intelligibility.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.2
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• pp.817-821
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• 2012

In this paper we applied the optimal mixture number estimation technique in GMM(Gaussian mixture model) using BIC(Bayesian information criterion) and MDL(minimum description length) as a model selection criterion for environmental sounds recognition. In the experiment, we extracted 12 MFCC(mel-frequency cepstral coefficients) features from 9 kinds of environmental sounds which amounts to 27747 data and classified them with GMM. As mentioned above, BIC and MDL is applied to estimate the optimal number of mixtures in each environmental sounds class. According to the experimental results, while the recognition performances are maintained, the computational complexity decreases by 17.8% with BIC and 31.7% with MDL. It shows that the computational complexity reduction by BIC and MDL is effective for environmental sounds recognition using GMM.

• The Journal of the Acoustical Society of Korea
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• v.39 no.3
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• pp.143-149
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• 2020

This paper presents the effect of the feature extraction methods used in the audio preprocessing on the classification performance of the Convolutional Neural Networks (CNN). We extract mel spectrogram, log mel spectrogram, Mel Frequency Cepstral Coefficient (MFCC), and delta MFCC from the UrbanSound8K dataset, which is widely used in environmental sound classification studies. Then we scale the data to 3 distributions. Using the data, we test four CNNs, VGG16, and MobileNetV2 networks for performance assessment according to the audio features and scaling. The highest recognition rate is achieved when using the unscaled log mel spectrum as the audio features. Although this result is not appropriate for all audio recognition problems but is useful for classifying the environmental sounds included in the Urbansound8K.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1187-1190
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• 2007

This study aims to induce acoustic environmental characteristics which could be used for soundscape design by carrying out factor analysis on sound source image and cognition analysis on subjects' responses on selective questions due to class differences. The results of this study are as follows ; Satisfaction rate differences on exterior acoustic environment due to sensitivity and residence year were revealed. After factor analysis of living sound sources' image, it is known that natural sound, traditional sound, socials traffic sound, rural sound, religious sound and the others are main factors. Social traffic sound is the most one that should be eliminated and traditional sound is selected as a most Korean-like sound. Natural sound is evaluated as the most one that should be preserved and the most retrospectively one.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.05a
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• pp.101-106
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• 2002

최근 사무환경에서 컴퓨터 사용시간이 급증함에 따라 컴퓨터 소음의 불쾌감으로 인한 저소음형 컴퓨터에 대한 요구가 증가하고 있다. 이에 따라 효율적인 소음조절을 위하여 컴퓨터 소음에 대한 실태 조사를 위하여 설문조사를 실시하였으며, 물리적 측정치와 더불어 심리음향학적 각종 파라메타를 계산하였다. 또한 일반적 업무 Task가 주어진 상태에서 컴퓨터 소음에 대한 근무자의 상하한계치 설정을 위한 청감실험을 실시하였다. 설문조사 결과, 가장 시끄럽게 인식되는 소음은 팬소음(사용자 컴퓨터)과 키보드 사용음(타인 컴퓨터)으로 나타났으며, 약 55%의 사용자들이 보통 컴퓨터 소음에 대해 시끄럽게 느끼고 있는 것으로 나타났다. 또한 현재 사용중인 컴퓨터의 소음에 대해 사용자의 약 20% 정도만이 조용하게 느끼며, 컴퓨터 소음이 업무효율을 떨어뜨린다는 응답도 약 35%로 나타났다. 팬소음, CD-Rom 구동음, HDD 작동음에 대해 청감실험을 실시한 결과, 각 소음의 상하한치는 각각 31∼51dB(A), 34∼54dB(A), 34∼58dB(A)로 나타났다.

• Journal of the Ergonomics Society of Korea
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• v.1 no.2
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• pp.33-37
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• 1982

인간의 가청 영역은 어린이의 경우에 20 Hz-20KHz로 알려져 있다. 그러나, 20Hz 이하의 초저주파 영역에서도 그 음압 레벨이 높은 경우에는 인간이 감지할 수 있다는 사실이 알려졌는데, 그것은 듣느다기 보다는 느낀다는 것으로 표현되고 있다. 초저주파 음이 인간에게 미친다고 생각되는 좋지않은 영향 때문에, 60년대말 이후에 새로운 종류의 연구 과제로서, 음향학자, 심리학자, 의학자 등에 의해 활발히 연구되고 있다. 게다가 경제의 고도성장 및 환경 개선의 노력에 따라, 대기 오염, 가청 소음, 진동 등의 전형적인 환경 공해 외의 초저주파음 공해에 대한 사람들의 인식과 불평이 문제시 되고 있다. 즉, 고주파수의 음이 잘 소음된 곳에서, 소리가 잘 들리지는 않으나 항상 사람들을 불안하게 하는 그 무엇이 있다는 것이다. 이에따라 지난 몇 년간 인간의 산업 활동과 관계 있는 높은 레벨의 초조주파 소음의 발생원이 확인되었고, 그에 따른 대책 및 설계 단계에서의 고려가 요구되고 있다.

• The Journal of the Korea Contents Association
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• v.10 no.12
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• pp.27-33
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• 2010

In this study, we conducted the classification experiments with GMM (Gaussian Mixture Model) from combining the extracted features by using microphone, Gyro sensor and Acceleration sensor in 9 different environment types. Existing studies of Context Aware wanted to recognize the Environment situation mainly using the Environment sound data with microphone, but there was limitation of reflecting recognition owing to structural characteristics of Environment sound which are composed of various noises combination. Hence we proposed the additional application methods which added Gyro sensor and Acceleration sensor data in order to reflect recognition agent's movement feature. According to the experimental results, the method combining Acceleration sensor data with the data of existing Environment sound feature improves the recognition performance by more than 5%, when compared with existing methods of getting only Environment sound feature data from the Microphone.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.31 no.4
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• pp.22-28
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• 2002

건축물의 실내 음향계획 및 평가를 위해 활용되고 있는 건축음향 프로그램에 대해서 소개를 하고자 한다.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.2
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• pp.41-49
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• 2016

P city government considers to treat a part of food waste leachate in a municipal wastewater treatment plant (MWWTP), as the capacity of an existing combined treatment plant for food waste leachate is lower than the generation of food waste leachate in the city. Furthermore, the combined treatment plant also treats landfill leachate and directly discharges the effluent to the sea, which may result in a potential environmental problem. Therefore, this study examined the feasibility of the addition of food waste leachate and the effluent of the combined treatment facility on the MWWTP. Acceptable addition amount of the food waste streams, increased pollution loading on the MWWTP, and the treatment cost were estimated according to four scenarios. All the scenarios estimated that the MWWTP would receive most of the food waste streams according to the manual of the ministry of environment with little increase of pollution loading.