• The Journal of the Acoustical Society of Korea
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• v.40 no.6
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• pp.593-606
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• 2021

The present study investigated the sounds at 13 points in the four districts in Cheongju including commercial district, historic district, urban walking district and university campus in order to realize the soundscape of the city. In order to this, questionnaire survey was conducted to 65 citizens and 5 acoustic experts on sites to find both sound loudness and annoyance of each district. At the same time, information about loud, unpleasant, preferred and representative sound of each district were acquired by selecting three from 35 sounds which consist of natural, artificial and machinery sounds. As a result, it was found that there is a very close correlation between sound loudness and annoyance. Through the analysis of sounds at each district, it was revealed that machinery sounds dominate in commercial area as figure sound, It was also shown that artificial and natural sounds dominate in historic area, artificial sounds in both urban area and university campus respectively. Laboratory listening tests were undertaken to 20 people using recorded sounds and video captured on site. The results denote that machinery and artificial sounds are regarded as most loud, machinery sounds as most unpleasant, natural and artificial sounds as most pleasant which shows similar tendency of on-site evaluation.

• The Journal of the Acoustical Society of Korea
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• v.26 no.4
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• pp.136-143
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• 2007

This experiment was performed to find out the effects of the cicadas' songs on the psychological responses in adolescents. As a basic coulee, the experiment to set up 'Acceptable & Unacceptable' was performed. As a further coulee, five kinds of the cicadas' songs heard frequently were analyzed and adjectives expressing the feeling to cicadas' songs were factor-analyzed, and psychological responses to auditory sensations were analyzed through regression equations. As a result, the effect of the Cryptotympana atrata's song, the Meimuna opalifera's song and the traffic noise are similar in the degree of disturbing the meditation but they are less disturbing than the white noise. The experiment for adjectives expressing was performed, because it is possible that cicadas' songs affect adolescents as a noise. Cicadas' songs can be expressed with three kinds of factors. First factor is [Annoyance], second factor is [Strength] and third factor is [Rhythm]. The first factor dominates in the songs of the Cryptotympana atrata and the Platypleura kaempferi who generate steady sound, and the third factor dominates in the songs of the Meimuna opalifera, the Leptosemia takanonis and the Oncotympana fuscata who generate fluctuating sounds. The loudness of sound didn't affect on the third factor but the emotional values of the fist and the second factors are linearly proportional to the loudness. The analysis results of the first factor associated with noise showed that the annoyance of adolescents is increased in the order of white noise - the Platypleura kaempferi - the Cryptotympana atrata, if the loudness of sounds are generated equally.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8B
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• pp.539-546
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• 2007

For better performance and to avoid member service annoyance that results due to joining-clients' waiting durations and time-outs when there are more than one client wanting to join concurrently for Personal Broadcasting System service, there is a need for improving concurrent member joining mechanism. For a more efficient and better performing, this paper apply Overlay Multicast based mini-Overlay Broadcasting Control Protocol(mOBCP) Algorithm on Personal Broadcasting System. mOBCP proposed is performance-effective mechanism, since it considers the case of how fast will children, concurrently, find and join new parents when paths to existing parents are in Failure. The performance comparison, in terms of tree construction time variation and Latency are done through simulations and the results conclude in favour of the Proposed mOBCP.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.5
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• pp.443-453
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• 2012

This study examines visual perception and spatial satisfaction according to lighting conditions. Field measurements and surveys were performed in three rest space of university buildings where various lighting conditions were employed. Results indicate that overall impression of space improved when low color temperature, such as 3,000 K governed overall lighting environment and accent lighting was used for wall surfaces. Lighting conditions that kept uniform illuminance levels using area light sources containing fluorescent lamps with 6,500 K failed to keep favorable spatial satisfaction for space. High color temperature was not recommended for lighting in rest space. Asymmetrical illuminance levels formed by low color temperature such as 3000 K is recommended to keep positive mood and improve spatial satisfaction in rest space. Overall impression of the space was influenced by visual comfort, color temperature, spatial satisfaction and brightness. Spatial satisfaction for space was effectively impacted by psychological comfort, color temperature and overall impression for lighting conditions. Psychological comfort in space was influenced by color temperature, spatial satisfaction and visual annoyance from reflected light.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.2
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• pp.99-104
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• 2013

Assessment of noise exposed population is to check the environmental noise level and social influence in order to reduce the risks such as annoyance and disturbance that are generated by environmental noise. Also, this method suggests the preferential noise abatement policy and action plan by accurately finding the area that the noise causes harmful effect to human health. Recently, a noise map, which can predict noise in comprehensive areas, is used for the assessment of noise exposed population, breaking from the methods using existing measures. In particular, countermeasure for the noise can be considered more effectively by using assessment methods of noise exposed population for specific noise levels, areas, and building types which are the main input factors in noise maps. In this study, assessment methods of noise exposed population by using 2 dimensional noise map are compared with those by 3 dimensional noise map.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 1994.05a
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• pp.11-17
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• 1994

The increase of road traffic niose in residential area has been considered to be a serious environmental problem to deteriorate a living condition. The understanding of noise environment in multiple family housing is needed for noise reduction. This study attempts to find out the characteristics of noise environment. For this purpose, the field survey has been carried out to investigate the noise environment(sound level, quality of sound) and the residents' responses(noiseness, annoyance) for noise environment based on 173 households living in 3 apartment compounds built in Pusan according to site location. The major findings are as follows : 1. The sound levels by road traffic noise were measured by dB(A) and dB(Lin). The sound levels were : 77.0dB(A), 86.6dB(Lin) in D-Apt, 73.3dB(A), 82.6dB(Lin) in K-Apt, and 59.1dB(A), 74.6dB(Lin) in M-Apt. Especially, the difference between dB(A) and dB(Lin) was very big in the cae of M-Apt with a barriers for traffic noise reduction. 2. The internal sound levels were shown the soudn attenuation by horizontal distance and by opening or shuting condition of windows.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.918-922
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• 2007

Aero-pulsation noise, generally caused by geometric asymmetry of a rotating device, is considerable source of annoyance in passenger cars using the turbocharged diesel engine. Main source of this noise is the compressor wheel in the turbocharger system, and can be reduced by after-treatment such as silencers, but which may increase the manufacturing cost. More effective solution is to improve the geometric symmetry over all, or to control the quality of components by sorting out inferior ones. The latter is more effective and reasonable than the former in view of manufacturing. So, an appropriate discrimination method should be needed to evaluate aero-pulsation noise level at the production line. In this paper, we introduce the accurate method which can measure the noise level of aeropulsation and also present its evaluation criteria. Besides verifying the reliability of a measurement system - a rig test system -, we analyze the correlation between the results from rig tests and those from vehicle tests. The gage R&R method is carried out to check the repeatability of measurements over 25 samples. From the result, we propose the standard specification which can discriminate inferior products from superior ones on the basis of aero-pulsation noise level.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.436-441
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• 2007

This study was carried out to evaluate health effects of aircraft noise using THI(Todai Health Index). The questionnaire survey was conducted around the Gimpo International Airport in Seoul, Korea from 8 August to 9 September. Study subjects, 614 residents, were divided into three groups following to the aircraft noise level: under 75WECPNL(area(1)), $75{\sim}80$WECPNL(area(2)) and $80{\sim}85$WECPNL(area (3)). Twelve scale scores are converted to dichotomous variables based on scale scores of 90 percentile value or 10 percentile value in the control group. Logistic regression analysis taking twelve scores converted as the dependent variables and WECPNL(area), age, gender as the independent variables is conducted. Significant dose-response relationships are found in the scale of MOUT, DEPR, NERV, LIFE, where p denotes significance probability of trend test. Factor analysis was carried out and 2 factors are extracted which may be called "somatic factor" and "mental factor". The dose-response relationship with these factors and noise exposure is not clear. But strangely the odds ratio of mental factor in area 2 is the highest and the annoyance of this area is also higher than other areas.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.2
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• pp.109-114
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• 2016

Nowadays, lower gear vibration and noise are necessary for drivers in automotive gearbox, which means that transmission gearbox should be optimized to avoid noise annoyance and fatigue before quantity production. Transmission error (T.E.) is the excitation factor that affects the noise level known as gear whine, and is also the dominant source of noise in the gear transmission system. In this paper, the research background, the definition of T.E. and gear micro-modification were firstly presented, and then different transmission errors of loaded torques for the spur gear pair were studied and compared by a commercial software. It was determined that the optimum gear micro-modification could be applied to optimize the transmission error of the loaded gear pair. In the future, a transmission test rig which is introduced in this paper is about to be used to study the T.E. after gear micro-geometry modification. And finally, the optimized modification can be verified by B&K testing equipment in the semi-anechoic room later.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.225-228
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• 2004

환경소음에 관한 연구는 주로 소음노출지역에 대한 소음 측정 및 사회적 조사(Social Survey)를 토대로 이루어 졌다. 이는 장기간 소음에 노출된 사람에 대한 소음평가의 수단뿐만 아니라 소음관련 법안 제정에 있어서 규제치를 결정하는 기준으로도 사용될 수 있다. 이에 반하여 본 논문에서는 소음에 대한 순간적인 반응 즉, 짧은 순간의 소음노출에 대한 주관적 반응을 알아보고자 하였으며, 방법적 측면(Methodology)에서의 제약으로 인하여 가상의 음 재현장치의 구성을 통하여 일반인을 대상으로 청감반응실험을 할 수밖에 없다. 먼저 항공기, 기차, 자동차 소음의 샘플을 녹음하여 일련의 신호처리 과정을 통하여 청감반응실험에 사용될 음원을 만들고, 청력검사를 통하여 청각에 이상이 있다고 판단되는 피검자의 데이터는 배제시킨 후 실험을 행하였다. 이러한 청감반응실험을 통하여 소음원의 종류, 성별, 연령, 소음 민감도 등에 따라 소음에 대한 성가심, 불쾌감의 정도는 다르게 나타남을 알 수 있었다.