• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.176-179
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• 2005

A case-study in classroom acoustics was conducted and the effects of two types(system air conditioner and packaged air conditioner) of air conditioner were investigated. Acoustical measurements were made in two different classrooms. Each classroom has different acoustics showing sound quality of air conditioner. Mental concentration test was conducted to evaluate the effects of air conditioner noise with different sound presure level(dBA). Speech intelligibility test was also planed with adopting Korean phonetic balanced words.

• 교육시설 논문지
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• 제18권5호
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• pp.3-11
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• 2011

In this study, the effect of treating 1-dimensional diffusers on the classroom acoustics was investigated to determine if the diffuser are beneficial for performing the preferred acoustical conditions for speech. A 1/10 scale model of a classroom was used to measure the acoustical parameters, T30, $C_{50}$, STI and SNR in that room. The room acoustical conditions were varied by treating diffusers either on the front or side walls of the classroom. When the diffusers were treated on the side walls around the student's areas, a shorter reverberation time at low frequencies was obtained and resulted in performing uniform reverberation times across the frequency bands. The $C_{50}$ values at mid- and high-frequencies were increased by treating the diffusers either on front or side wall surfaces. The highest STI and SNR values were obtained when the diffuser was treated on the front wall around the teacher's areas. It is found that diffusers are beneficial to increase the intelligibility of speech for the rear seats of the rooms.

• 한국음향학회지
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• 제42권2호
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• pp.113-123
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• 2023

본 논문에서는 국내 초·중·고 및 대학교 학습공간의 음향 상태에 관해 설명하고 국내 교육시설의 음향 기준 제정의 필요성을 제시하였다. 여러 나라의 학교시설 내 다양한 학습공간에서 요구되는 배경소음, 잔향시간, 그리고 차음 설계의 음향 기준을 이해하기 위해 학교시설 음향설계기준 및 지침을 소개하였다. 국내 초·중·고 및 대학교 학습공간의 음향 상태를 파악하기 위해 현장 측정 결과를 바탕으로 하였으며, 그 결과에서는 공석과 만석 상태의 음향 특성, 배경 소음레벨, 그리고 차음성능을 제시하여 비교하였다. 실제 대학 강의 현장에서 좋은 음성 명료도를 성취하기 위한 음향지표 값도 제시하였다.

• 교육시설 논문지
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• 제20권1호
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• pp.37-44
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• 2013

The present study examines the effects of periodic type diffusers for producing the preferred acoustics for speech and determines the more successful configurations of sound-absorbing and diffusing treatments for achieving good acoustics in classrooms. The measurements were carried out in a 1/10 scale model classroom systematically adding diffusers to one or more of four surfaces of the room. A total of 13 combination of diffusers with absorptive treatments were investigated. Adding diffusers on the ceiling were more effective to increasing the early-arriving reflection energy($G_{50}$) than adding absorptive materials on the entire ceiling. The late arriving reflection energy($G_{late}$) was decreased with increasing amounts of diffusing treatments of upper front or rear wall and this resulted in achieving higher early-to-late ratios($G_{50}$). Adding diffusers on the upper front wall($AC_{100}DUFW_{26}$) achieved more uniform acoustical conditions over the receiver positions than adding diffusers on the upper rear wall($AC_{100}DUFW_{26}$). Adding diffusers on the ceiling and absorptive materials on the lower front wall($AC_{75}DC_{25}ALFW_{26}$) achieved better acoustical conditions than adding the absorptive materials on the entire ceiling and lower front wall($AC_{100}ALFW_{26}$).

• 산업기술연구
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• 제41권1호
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• pp.15-20
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• 2021

This work proposes a simple method to use the added absorption per person values to predict the expected values of the acoustical conditions in occupied classrooms. This method is based on the effects of the values of added absorption per person on the unoccupied total absorption values of the classrooms and on other room acoustical parameters. The total sound absorption in an unoccupied classroom can be calculated from measured reverberation times in the classroom. The expected occupied absorption can be calculated using equation which was obtained in a previous study (Choi, 2017) by fitting a linear regression line to a plot of total occupied absorption versus the corresponding unoccupied total absorption values measured in 12 university classrooms. The ratios of occupied-to-unoccupied sound absorption are used to predict increments in the values of acoustical parameters that result when occupants are added to the rooms.

• The Journal of the Acoustical Society of Korea
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• 제28권2E호
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• pp.60-65
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• 2009

The present study aims to investigate the effects of sound diffusers and absorbers on the sound clarity in classrooms. In order to do this, computer simulations were carried out to find the effective area of treatment which could enhance the sound clarity in the room. Acoustic measurements were undertaken in a lecture room with several conditions changing the surface of walls and ceilings with diffusers and absorbers. Diffusion and absorption treatments were applied to the side walls, rear wall and the ceiling of the classroom. SPL, RT, D50, RASTI were measured at 9 measurement points with one sound source and MLS was used as the sound source signal. The results show that higher sound clarity was obtained when diffusers were applied to rear walls and ceiling rather than side walls. Also, it was confirmed that absorption increased sound clarity more effectively with smaller amount in comparison with diffusers. It was also concluded that the effects of sound diffusers and absorbers on the sound clarity could be obtained distinctly at the rear area of the classroom.

• 융합신호처리학회논문지
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• 제8권1호
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• pp.32-38
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• 2007

강의실에서의 환경조건을 확립하기 위해 PA(Public-Address)를 사용한 경우와 PA를 사용하지 않은 경우의 두 가지 패턴으로 임펄스 응답을 측정하였다. 측정결과에 의해 음성 명료도에 관련된 음향물리지표를 계산하고 PA 유무에 의한 각 지표의 차이를 검토하였다. 그리고 임펄스 응답을 이용하여 4연속 음절 명료도 시험을 하여 잔향에 따른 PA사용이 어느 정도 음성 듣기를 향상시키고 있는가도 검토하였다. 그 결과, 잔향이 어느 정도 적은 경우에는 PA에 의한 음압레벨의 향상이 충분한 명료도의 개선이 되는 가능성이 있으나 잔향이 긴 경우에는 제시 음압레벨을 높여도 PA 시스템에서는 명료도의 개선이 기여되지 않는다는 것을 알 수 있었다.

• 한국음향학회지
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• 제31권3호
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• pp.129-141
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• 2012

본 논문은 강의실의 실내흡음력이 증가함에 따라 발생하는 물리적 음명료도 (D50, STI)의 변화가 한국어와 중국어의 주관적 음이해도 (음성요해도)에 미치는 영향을 조사하였다. 이를 위해 중규모 강의실에서 흡음재를 설치하기 전과 후의 물리적 음향성능을 측정하고, 음절요해도 테스트 법을 사용해 음성요해도를 평가하였다. 음성요해도 평가시 한국어와 중국어의 두 가지 언어를 대상으로 진행함으로써 두 언어의 특성에 따른 음성요해도의 차이를 비교하였다. 실험결과 흡음재를 설치함에 따라 물리적 음명료도가 증가하였으며, 음성요해도 또한 증가함을 알 수 있었다. 또한 동일한 조건에서 음절요해도 테스트를 수행한 결과 한국어보다 중국어의 음성요해도가 더 높은 것으로 평가되었으며 이것은 한국어와 중국어의 발음특성의 차이에 기인한 것으로 사료된다. 한편 물리적 음명료도와 주관적 음명료도의 상관관계 분석결과 ($R^2$) D50의 경우 한국어는 0.696, 중국어는 0.707로 나타났으며 STI의 경우 한국어는 0.651, 중국어는 0.665로 매우 높은 상관관계가 있음을 알 수 있었다.

• 한국소음진동공학회논문집
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• 제15권3호
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• pp.320-328
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• 2005

Last target of architectural acoustics is that people wish to convey voice effectively from the space adaptively in use purpose in building. But, how exactly through space sound (sound source) that wish to deliver from indoor can be passed method to do quantification and evaluate quantity of sound by method to serve indoor architectural acoustics estimation summer period and methods to estimate definition propose. This Study searches special quality of sound source about MLS signal that is occurred short-answer sound source (pistol sound source) and nondirectional speaker among indoor sound estimation method, and measure and analyzed reverberation time (RT60), definition (C80, D50) by regulation of each ISO 3382 in age place (classroom, hall, gymnasium). Analysis result and sound factor among could know that d of two sound sources converges in measurement error extent about reverberation time (RT60) of analysis incidental and sound factors and value shows change irregularly about sound factor of D50, C80, pistol sound source judged there is problem. Also, could know that problem is happened in deflection except reverberation time is in deflection analysis with wave that measure each in fixed distance in branch. Finally, when differ size of sound source and measure about change of sound pressure level in case measure sound pressure level giving difference about 10 dB, sound factor could know that there is no different effect.

• 한국소음진동공학회논문집
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• 제25권7호
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• pp.462-469
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• 2015

This study was carried out to examine characteristics of various acoustic indicators evaluating speech intelligibility such as reverberation time(T₃₀), D₅₀, C₅₀ and speech transmission index(STI) in Korean elementary school classrooms. Results showed that mean T₃₀ at middle frequencies(500 Hz to 2000 Hz) measured in 9 classrooms was about 0.75 s, which exceeds a regulation specified on American National Standards(ANSI); 0.60 s. Mean D₅₀, C₅₀ and STI were 60 % to 66 %, +2 dB to +3 dB, and 0.65, respectively. The maximum difference in D₅₀ and C₅₀ according to different receiver points in a classroom was 13 % and 2.5 dB, while the maximum difference in T₃₀ was 0.03 s. Whereas STI measured in classrooms has relatively low correlation with other indicators, correlation between D₅₀ and C₅₀ was high, R²=.9964. In addition, T₃₀ and C₅₀ were fitted well as logarithmic regression curve with R²=.9610. It was +3.73 dB in C₅₀ and 68 % in D₅₀ which are the value corresponding to 0.60 s in T₃₀ on this curve.