• 한국감성과학회:학술대회논문집
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• 한국감성과학회 1999년도 추계학술대회 논문집
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• pp.216-221
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• 1999

A mental task combined with noise background is an effective model of laboratory stress for study of psychophysiology of the autonomic nervous system (ANS). The intensity of the background noise significantly affects both a subjective evaluation of experienced stress level during test and the physiological responses associated with mental load in noisy environments. Providing tests of similar difficulties we manipulated the background noise intensity as a main factor influencing a psychophysiological outcome and the analyzed reactivity along withe the noise intensity dimension. The goal of this study was to identify the patterns of ANS responses and the relevant subjective stress scores during performance of word recognition tasks on the background of white noise (WN) of the different intensities (55, 70 and 85 dB). Subjects were 27 college students (19-24 years old). BIOPAC, Grass Neurodata System and AcqKnowlwdge 3.5 software were used to record ECG, PPG, SCL, skin temperature, and respiration. Experimental manipulations were effective in producing subjective and physiological responses usually associated with stress. The results suggested that the following potential autonomic mechanisms might be involved in the mediation of the observed physiological responses: A sympathetic activation with parasympathetic withdrawal during mild 55 and 70dB noise (featured by similar profiles) and simultaneous activation of sympathetic and parasympathetic systems during intense 85dB WN. The parasympathetic activation in this case might be a compensatory effect directed to prevent sympathetic domination and to maintain optimal arousal state for the successful performance on mental stress task. It should be mentioned that obtained results partially support Gellhorn's (1960; 1970) "tuning phenomenon" as a possible mechanism underlying stress response.

• 교육시설 논문지
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• 제28권3호
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• pp.3-14
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• 2021

Speech information of teachers is transmitted to students in classrooms so that appropriate aural environment should be provided for academic purposes. Many researches have been undertaken for classroom acoustics, and acoustic standards of domestic classrooms were suggested based on the reverberation time and background noise level. However, these standards are suitable for middle and high schools and so not consider the auditory ability by ages. As a precedent research, the present study was begun to suggest an acoustic standard for lower grade elementary school classrooms with children under age 9 who have not normal auditory ability. In order to do this, acoustic performances of the lower grade classrooms were measured and compared with the general classrooms. Also, change of acoustic parameters depending on the desk layout was measured and analyzed. The measured acoustic parameters were background noise, signal to noise ratio, RT, STI, D₅₀, and IACC. As a result, it was found that background noise is exceed the standard of 35dB(A) at the schools along the road sides. Also, it was shown that most of acoustic parameters are higher in the classrooms built recently rather than the old classrooms. Generally, there are not much difference of acoustic parameters among the various desk layouts but, better acoustic performances are acquired at the center line and the seats near sound source. Also, Higher IACC was measured at the seats on the center line facing the source squarely.

• 월간산업보건
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• 통권293호
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• pp.62-64
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• 2012

• 한국컴퓨터정보학회논문지
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• 제17권8호
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• pp.91-97
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• 2012

본 논문에서는 각 프레임에서의 음성신호 및 비음성신호 구간을 검출하는 음성인식 알고리즘을 제안한다. 그리고 음성신호 및 비음성신호 구간의 검출에 따라서 각 프레임에서 잡음을 제거하는 멀티밴드필터에 의한 환경잡음억압 알고리즘을 제안한다. 이 알고리즘은 음성으로부터 특징 파라미터를 추출하여 필터뱅크의 서브밴드 영역에서 잡음을 제거하는 방법이다. 본 실험에서는 환경잡음억압 알고리즘의 성능을 멀티밴드필터를 사용하여 각 프레임에서 잡음을 제거하는 실험결과를 나타낸다. 잡음에 의하여 오염된 음성에 대하여 스펙트럴 왜곡률을 사용하여 본 알고리즘이 유효하다는 것을 확인한다.

• 한국소음진동공학회논문집
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• 제15권8호
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• pp.980-987
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• 2005

It is very difficult to reduce ambient noise level in the downtown. The best method is to improve the sound amenity of the districts, considering concept of soundscape. This study aims to survey the effect of introducing sound and masking to reduce the background noise level. We carried out the evaluating test for 18 introducing sounds varied S/N ratio(-5, 0, +5) in the city riverside. In these test, subjects evaluated the sound environment with five bipolar adjective scales. It was evaluated that introducing sounds improved the sound environment, and that S/N +5 dB was very appropriate to mask the background noise. But the hearing level was suggested to be S/N 0 dB or less.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.607-610
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• 2005

It is very difficult to reduce traffic noise level in the downtown. The best method is to improve the sound amenity of the districts, considering concept of soundscape. ?his study aims to survey the effect of introducing sound and masking to reduce the background noise level. We carried out the evaluating test for 18 introducing sounds varied S/N ratio(-5, 0, +5) in the city riverside. In these test, subjects evaluated the sound environment with five bipolar adjective scales. It was evaluated that introducing sounds improved the sound environment and that S/N + 5dB was very appropriate to mask the background noise. But the hearing level was suggested to be S/N 0 dB or less.

• 대한조선학회논문집
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• 제37권1호
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• pp.111-117
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• 2000

수중소음 계측의 가능성을 파악하기 위하여 KRISO 캐비테이션 터널의 음향학적 특성을 조사하였다. 유속과 압력을 변화시키면서 배경소음을 100kHz까지 계측하였으며, 소음계측을 수행하기 위하여 건설된 캐비테이션 터널[HYKAT(독일), GTH(프랑스)등]들의 배경소음과 비교하였다. 배경소음원을 조사하기 위하여 B&K 3550 FFT 분석기를 이용하여 구조물의 진동과 소음과의 상관도를 해석하였다. 실험결과로부터 소음계측 가능성을 파악할 수 있었으며, 소음환경의 개선방안도 도출할 수 있었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.599-602
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• 2005

This paper describes a experimental study determining the effects of the type and loudness of introducing sounds on the amenity and the masking degree of background noise. 132 relative test sounds with 11 types of introducing sounds and 3 steps of road traffic noise were presented to 29 subjects through headphone in the laboratory experiment. Seven scale of polar adjective such as 'Strong Weak', 'Pleasant Unpleasant', 'Clear Unclear', 'Suitable Unsuitable', 'Comfortable-Discomfortable' was employed for the evaluation of amenity. And Seven scale of mono polar adjective such as 'Very-Not at all' was employed for the evaluation of masking degree against road traffic noise. The results are as follows; Green music was evaluated the highest amenity among test sounds and murmurs of a stream, signal music, song of a bird, crying of insect was showed the amenity rank of order. The softer and weaker introducing sound was evaluated more suitable and comfortable under the road traffic noise. So adequate level of introducing sounds was considered for the desirable urban soundscape. Also the louder sounds compared to background noises had greater masking effects. But similar levels of introducing sounds were recommended considering both good amenity and masking effects.

• Ocean and Polar Research
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• 제44권4호
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• pp.287-296
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• 2022

High-frequency (HF) radar measures sea surface currents from the radio waves transmitted and received by antenna on land. Since the data quality of HF radar measurements sensitively depend on the radio wave environment around antenna, Antenna Pattern Measurements (APM) plays an important role in evaluating the accuracy of measured surface currents. In this study, APM was performed by selecting the times when the background noise level around antenna was high and low, and radial data were generated by applying the ideal pattern and measured pattern. The measured antenna pattern for each case was verified with the current velocity data collected by drifters. The radial velocity to which the ideal pattern was applied was not affected by the background noise level around antenna. However, the radial velocity obtained with APM in the period of high background noise was significantly lower in quality than the radial velocity in a low noise environment. It is recomended that APM be carried out in consideration of the radio wave environment around antenna, and that the applied result be compared and verified with the current velocity measurements by drifters. If it is difficult to re-measure APM, we suggest using radial velocity in generating total vector with the ideal pattern through comparative verification, rather than poorly measured patterns, for better data quality.

• 대한전자공학회논문지SP
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• 제39권4호
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• pp.361-369
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• 2002

제한된 구역내의 고정(static)된 감시 카메라를 통해 입력된 영상 데이터에 대해 움직임이 있는 물체를 검출하기 위해서는 주위 잡음(noise)에 대한 민감성(sensitivity)과 상황변화에 대해 대처할 수 있는 강인한 알고리즘이 요구된다. 본 논문에서는 이러한 잡음이나 갑작스런 상황의 변화에 적절히 대응하여 움직임 물체를 추출하고 추적하는 효율적인 알고리즘을 제안한다. 초기 배경 모델(background model) 영상에 의해서 입력되는 영상 내에 이동 물체가 존재할 경우 각 화소의 주변의 변화를 고려하여 움직임 영역을 검출하였다. 움직임 영역의 화소들의 잡음 제거를 위해 형태학적 필터(morphological filter)를 사용하였고, 8-연결 성분 표시(connected component labeling)에 의해 개별적인 물체의 움직임을 검출하였다. 마지막으로 다양한 환경과 모델에 따른 실험결과와 통계적인 분석을 제시하였다.