• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2006년도 춘계학술대회논문집
• /
• pp.1194-1197
• /
• 2006

Recently, international standard for measurement of sound absorption in a reverberation room has been amended. In the revised version, temperature, humidity and air pressure conditions are strictly restricted and also the concrete procedures are presented to reduce the differences in test results by adding inspection of diffusion, measurement uncertainty etc. In this paper, the systematic tests are conducted based on the inspection guide of diffusion defined by ISO 354 and the effects of diffusers on the measurement of sound absorption ratio are considered. As a result, we perceived that the averaged sound absorption ratio in mid and high frequency range is expected to measure around $0.05{\sim}0.1$ higher in high sound absorption material. Therefore, as for the reverberation room for measurement of sound absorption, we need to take into consideration not only the spatial standard deviation of sound pressure mandated by ISO 3741, but also, inspection regulation of diffusion showed by ISO 354.

• Journal of Electrical Engineering and information Science
• /
• 제3권1호
• /
• pp.80-85
• /
• 1998

A theoretical calculation and an optical measurement method of normal-incidence absorption are proposed. By using a waveguide structure, optical interference and the problem of low level signal can be avoided in the measurement of normal-incidence absorption. The oscillator strength of intersubband absorption for a waveguide structure is calculated in Si(001), Si(110), and Ge(001) quantum wells. The polarization angle dependence of the measured and the calculated absorption strength can be obtained with the same waveguide structure, and be compared after normalization. The normal-incidence absorption in Si(110) and Ge(001) quantum wells is shown theoretically, and can be observed in the optical measurement using waveguide structures at the polarization angle of 90$^{\circ}$.

• 대한기계학회논문집B
• /
• 제35권12호
• /
• pp.1317-1324
• /
• 2011

대기중에 부유하고 있는 입자들의 광흡수량을 측정할 수 있는 기법을 소개한다. 본 연구에서 사용된 기법은 광열분광법이다. 광흡수 측정에 있어서 광열 기법의 장점은 광산란에 둔감할 뿐만 아니라 광산란 계수의 영향을 받지 않고 광흡수 계수를 직접적으로 측정할 수 있다는 것이다. 공기중 부유물질의 흡수 계수 측정의 시간 상수는 10 초이며, 실시간으로 고속도로 주변에서 흡수 계수를 측정하였다. 자동차 경주용 트랙, 공항, 또는 연구소 정문 등 차량 통행량이 많은 지역에서의 흡수 계수가 높게 측정되었는데, 이는 카본 부유물 입자에 의한 영향이라고 판단된다.

• Journal of the Optical Society of Korea
• /
• 제5권4호
• /
• pp.123-130
• /
• 2001

In this paper, we report measurement of absorption coefficient for various InGaAs MQW QCSE device structures. The absorption spectra over a range of QCSE were obtained from measured photocurrent spectra. The refractive index changes with applied electric field were calculated from the absorption spectra.

• 한국분무공학회지
• /
• 제7권2호
• /
• pp.1-6
• /
• 2002

It is necessary to develope a high frequency diode laser sensor system based on the absorption spectroscopy for the measurement of temperature of the spray flame. DFB diode laser operating near $2.0{\mu}m$ was used to scan over selected $H_2O$ transitions near $1.9{\mu}m\;and\;2.2{\mu}m$, respectively. The measurement sensitivity at wide range of sweep frequency was evaluated using multi-pass cell containing $CO_2$ gas. This diode laser absorption sensor with high temporal resolution up to 10kHz was applied to measure the gas temperature in the spray flame region of liquid-gas 2-phase counter flow flame. The successful demonstration of time series temperature measurement in the spray flame gives us motivation of trying to establish non-intrusive temperature measurement method in the practical spray flame.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2010년도 춘계학술대회 논문집
• /
• pp.197-200
• /
• 2010

In some cases it is important to be able to measure not only the total sound intensity on a panel surface in a vehicle cabin, but also the components of that intensity due to sound radiation and due to absorption from the incident field. For example, these intensity components may be needed for calibration of energy flow models of the cabin noise. A robust method based on surface absorption coefficient measurement is presented in his paper.

• Bulletin of the Korean Chemical Society
• /
• 제13권5호
• /
• pp.553-556
• /
• 1992

The ${CO}_2$ laser absorption measurement of ${CH}_3{CH}_2Br$ utilizing photoacoustic (PA) technique was performed using a cw and a pulsed ${CO}_2$ lasers. The absorption profile in the ${CO}_2$ laser wavelength region (9-10 ${\mu}$m) and the macroscopic small signal absorption cross section at 10P(20) (10.59 ${\mu}$m, 944 $cm^{-1}$) laser line were measured using a cw ${CO}_2$ laser. The laser fluence dependence on infrared multiphoton absorption (IRMPA) was also studied with a pulsed TEA ${CO}_2$ laser at 10P(20) laser line. In view of monotonic increase of PA signal with the rise of laser fluence, it was suggested that the anharmonicity in pumped vibration mode did not restrict ir multiphoton absorption in ${CH}_3{CH}_2Br$ system as found in large molecular system.

• 한국염색가공학회지
• /
• 제25권2호
• /
• pp.89-93
• /
• 2013

The electrochemical study has been enjoyed in many areas of chemistry. Through this approach using electrochemical measurement, empirical HOMO and LUMO values can be calculated by three methods such as absorption measurement, cyclicvoltammetry and computational calculations. In this study, 1,3-bisdicyanovinylindane was prepared and investigated toward its optical properties. The absorption intensities were changed depending on changes of pH. These absorption changes are induced by resonance form of 1,3-bisdicyanovinylindane. The electron delocalization in ${\pi}$ system is related to the resonance form. In according to this electron density distribution and HOMO/LUMO values of 1,3-bisdicyanovinylindane were simulated and calculated by Material Studio 4.3, absorption measurement and cyclicvoltammograms. The 1,3-bisdicyanovinylindane is one of the most attracted acceptor units in D-${\pi}$-A system. This attempt is useful to determine more detailed characteristics of the energy potentials.

• 한국음향학회지
• /
• 제40권3호
• /
• pp.254-260
• /
• 2021

시료의 흡음률 측정을 위해서는 비용이 많이 드는 잔향실 혹은 저주파수에서의 측정에 한계가 있는 임피던스 튜브를 사용한다. 본 논문에서는 마이크로폰을 사용하지 않고 단지 스피커 임피던스와 이로부터 도출된 Thiele/Small 변수만을 사용하여 시료의 음향임피던스와 흡음률을 구하는 기법을 제안하였다. 스피커의 등가회로를 이용하여 이 방법의 이론을 설명하였으며, 시료의 측정을 통하여 본 방법의 유효성을 증명하였다. 본 방법은 기존에 신뢰하기 어려웠던 저주파 대역에서의 흡음률을 매우 쉽게 측정할 수 있음을 확인하였다. 본 방법의 장점과 제한사항, 그리고 응용 분야에 대해서 검토하였다.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
• /
• pp.97-103
• /
• 2006

This work forcus on the development of gas sensor that measure the concentrations of exhaust gas using diode laser. Each diode laser for exhaust gas measurement is set to work at near-IR using both DA and WMS methods. Also use of fiber-coupled optical elements makes such a sensor rugged and easy to align. On-line data acquisition and processing can be performed with a PC running LabVIEW software, and absorption signals are measured simultaneously by multiplexing method. Finally, It were experimentally compared WMS (Wavelength Modulation Spectroscopy) with DA (Direct Absorption) for the accuracy.