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주문기(Joo, Mun-Ki),고효인(Ko Hyo-In),홍지영(Hong Ji-Young),오양기(Oh Yang-Ki) 한국건축친환경설비학회 2015 한국건축친환경설비학회 논문집 Vol.9 No.3
In recently, numbers of civil appeal about railroad noise are growing due to the deterioration railroad noise barrier walls. The regulation of sound barrier wall used sound absorption coefficient of sound proof panels must apply the average of sound absorption coefficient in four frequency ranges (250,500,1000,2000㎐). In the measurement , the regulation of sound absorption coefficient is satisfactory when the average value of sound absorption coefficient is over 0.7. However after installation of noise barrier wall, it isn"t know whether the performances of noise barrier walls are good or bad because of being not a management regulation of noise barrier wall. So in this study, the measurements of sound absorption coefficient and investigate on the present condition of noise barrier walls were carried out in the field and laboratory. As the results, the number of problem on the noise barrier wall were found out. According to the deterioration, a damaged part and bending problem and crack and deterioration of sound absorption material has appeared in the noise barrier wall. Particularly sound absorption coefficient of over 1㎑ frequency ranges were measured 0.8-0.52. It seemed to be clogged with the dust in the absorption material. So it is expected that the management regulation of railroad noise barrier wall is needed.
Interlayer film 재료 및 구성에 따른 접합유리 차음성능 비교
홍지영(Jiyoung Hong),고상원(Sangwon Ko),고효인(Hyo-In Koh),장승호(Seungho Jang) 한국소음진동공학회 2013 한국소음진동공학회 학술대회논문집 Vol.2013 No.10
It is well known that monolithic glass has specific coincidence dip allowing transmittance of noise around the critical frequency. Laminated glass, made of a polyvinyle butyral(PVB) interlayer sandwiched by two panes of glass sheet, has long served for the advantage in noise attenuation properties as well as the safety purpose. More research on the improvement of sound insulation performance is needed, considering much of the noise is still transmitted through the glass. As a preliminary study, authors have made several test specimens, varied combinations of glass and interlayer film, to optimize the acoustic performance. Experimental investigation was carried out to study the sound transmission loss of test specimens in the reverberation chamber by using sound intensity method. Several new applications, instead of the existing PVB laminated glass, show better results in sound transmission loss and low temperature have a bad influence on the acoustic performance.
이강성(Lee, Gang-Seong),주문기(Chu, Mun-Ki),고효인(Ko, Hyo-In),홍지영(Hong, Ji-Young),오양기(Oh, Yang-Ki) 한국건축친환경설비학회 2014 한국건축친환경설비학회 논문집 Vol.8 No.6
There are a couple of measurement standards in measuring the absorption coefficient of building materials. Impedance tube method and reverberation room method are those standardized absorption coefficient measurement methods. While applicable to the development stage of certain absorptive materials and the measurement of random incident absorption coefficient of multi layered absorption complex, they are unable to be applied to in-situ measurement. There are needs for the in-situ measurement for the assessment of the efficient of absorption materials and for the remodelling design of existing rooms. This research deals with an in-situ absorption coefficient measurement system which is based on the calculation of energy from impulse response of incident and reflected signal on the same axis
수종 불소함유 이장용 시멘트의 불소 유리량과 상아질로의 불소흡착정도
고효지,정현주 전남대학교 치과대학 1992 전남치대논문집 Vol.4 No.1
The purpose of this study was to determine the fluoride release levels of new fluoride-containing liner/base cements and the fluoride uptake by dentin surfaces. Ten specimens of each brand (Fuji ionomer TypeⅢ, Fuji Lining LC, Timeline, Vitrebond and XR ionomer) were made, polymerized and placed in fluoride-free distilled water at 37℃, 100% relative humidity for 24 hours. The extracting solution of specimen was exchanged and fluoride release was measured daily for the 30 days. For fluoride uptake study, twenty-five extracted human lower molars were sectioned longitudinally in the mesiodistal direction with a diamond disc. Five teeth were filled with each material and then stored at 37℃, 100% humidity for 4 weeks. Fluoride uptake by dentin from the test materials was evaluated using electron probe micro X-ray analyzer. The following results were obtained: 1. The amounts of fluoride release showed no significant difference between Fuji ionomer TypeⅢ and Fuji Lining LC, but showed significant difference between other groups. XR ionomer released significantly greater fluoride than any other group(P<0.001). 2. All the materials have a burst effect in which more fluoride released in then first 3 day and showed significant decrease over the test period(P<0.01). 3. XR ionomer group showed fluoride penetration to approximately 50㎛ deep in dentin. But other material groups showed very little fluoride uptake by dentin.