• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.111-118
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• 2003

Recently, environmental damage to urban area becomes serious problem due to the exhaust emissions by increasing the number of vehicle. Especially, exhaust emission from diesel vehicles are blown to be harmful to human health and environment. Photoacoustic Spectroscopy system is very useful technology for simultaneous and continuous measurement of the various components of the automotive exhaust gas. In this study, in order to reduce emission gases from automobile, we tried to develop the measurement system of Photoacoustic Spectroscopy. To improve performance of high sensitive Photoacoustic Spectroscopy system for automotive exhaust emissions, the shape of Photoacoustic Spectroscopy cell was optimized to use the flow analysis. And Exhaust emission data of the 1,500cc gasoline engine was fixed the working fluid. The characteristics of fluid flow for cell were analyzed by various conditions in detail.

• Proceedings of the Acoustical Society of Korea Conference
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• 1984.12a
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• pp.33-35
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• 1984

A new type single beam photoacoustic spectrometer suitable for measuring optical absorption of condensed powder matter with the automatic calibration capability of a source power spectrum is introduced. The signal processing until of this spectrometer consists of a photoacoustic cell a lock-in amp., a switching circuit and a personal computer. The measured optical absorption spectra of a few material by this method are good agreement with the results obtained by the double-beam photoacoustic spectrometer.

• Journal of the Korean Chemical Society
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• v.61 no.4
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• pp.139-142
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• 2017

Ethene ($C_2H_4$), which is produced in plants as they mature, was used to study its photoacoustic properties using photoacoustic spectroscopy. Detection of trace amounts, with $N_2$ gas, of $C_2H_4$ gas was also applied. The gas was tested in various conditions-temperature, concentration of the gas, gas cell length, and power of the laser- to determine their effect on the photoacoustic signal, the ideal conditions to detect trace gas amounts, and concentration of $C_2H_4$ produced by an avocado and a banana. A detection limit of 10 ppm was determined for pure $C_2H_4$. A detection of 5% and 13% (by volume) concentration of $C_2H_4$ was produced for a ripening avocado and banana, respectively, in closed space.

• Korean Journal of Optics and Photonics
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• v.2 no.1
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• pp.50-56
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• 1991

This paper describes several optical microphones, "optophone", where a low-power He-Ne laser beam is deflected by a reflecting diaphragm mounted on a photoacoustic cell. A comparision of an acousto-optic detection to a conventional microphone shows comparable sensitivities for the photoacoustic detection. The greatest application of these detections may be found where small volume spectro-phone cells are employed, or where conventional microphones cannot be employed because of high or low temperature or chemical corrosion problems. problems.

• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1513-1518
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• 2002

Kinetic studies on the water-gas shift reaction catalyzed by magnetite/chromium oxide and copper/zinc oxide were carried out by using an in situ photoacoustic spectroscopic technique. The reactions were performed in a closed-circulation reactor system using a differential photoacoustic cell at total pressure of 40 Torr in the temperature range of 100 to $350^{\circ}C.$ The CO2 photoacoustic signal varying with the concentration of CO2 during the catalytic reaction was recorded as a function of time. The time-resolved photoacoustic spectra obtained for the initial reaction stage provided precise data of CO2 formation rate. The apparent activation energies determined from the initial rates were 74.7 kJ/mol for the magnetite/chromium oxide catalyst and 50.9 kJ/mol for the copper/zinc oxide catalyst. To determine the reaction orders, partial pressures of CO(g) and H2O(g) in the reaction mixture were varied at a constant total pressure of 40 Torr with N2 buffer gas. For the magnetite/chromium oxide catalyst, the reaction orders with respect to CO and H2O were determined to be 0.93 and 0.18, respectively. For the copper/zinc oxide catalyst, the reaction orders with respect to CO and H2O were determined to be 0.79 and 0, respectively.

• Korean Journal of Optics and Photonics
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• v.22 no.2
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• pp.77-82
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• 2011

Reproducibility obtained by a minimum-volume cell for photoacoustic (PA) signals is strongly dependent upon the sealing materials and sealing efficiency. Therefore, we have proposed, designed, and constructed an apparatus to enhance the sealing efficiency, and we have examined the reproducibility of amplitude and phase of PA signals with a minimum-volume cell. In particular, we have measured the PA signal as a function of modulation frequency for various rubber O-rings by using our apparatus. The results show that a silicon rubber O-ring can improve the reproducibility of the PA signal and phase by up to 53.4% and 80.4%, respectively, compared to that obtained by using the conventional sealing material, vacuum grease.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.360-365
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• 1992

We constructed a photoacoustic cell and dewar in order to investigate the phase transition of the solids. The solid-liquid phase transition of a wood's metal was measured by a temperature controlled photoacoustic apparatus. It showed a good agreement with the reported value of the melting point, 343 K. The phase transiton of the wood's metal has been determined to be the first order transition, existing a latent heat, which is typical in the solid-liquid transition. In addition, a supercooling effect was observed by monitoring the photoacoustic signal as the temperature of the sample was decreased. The experiments have demonstrated the photoacoustic detection is an appropriate method to determine the order of transition in solid samples.

• Journal of the Korean Chemical Society
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• v.38 no.6
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• pp.469-472
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• 1994

• Proceedings of the Acoustical Society of Korea Conference
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• 1984.12a
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• pp.27-32
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• 1984

When chopped light inpinges on some condenced matters such as HgS, HgI2 and GaSe semiconductors, in an enclosed cell, the acoustic signals are produced within the cell. These acoustic signals were detected by using a gas-phase microphone in order to investigate the physical properties of the samples. In order to carry out investigation, PA-cell was first designed and made so as to produce higher sensitivity to acoustic signals. Second, an analysis of the photoacoustic spectrum of the various compounds was carried out to obtain the intensity of the PA-signal in terms of light wavelength and to calculate the energy band gaps occuring according to energy transitions. The agreement between the results obtained by this conventional PAS technique and the results obtained by the optical spectrum method was good. In additional analysis conducted on the basis of the R-G theory and the Sze theory are capable of determining the characteristics of energy transition of semiconductors.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.9
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• pp.589-594
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• 2016

P3HT:PCBM bulk heterojunction solar cells added with ferroelectric polymer were fabricated and characterized. By incorporating P3HT:PCBM solar cell with P(VDF-TrFE) ferroelectric additive, the power conversion efficiency was increased up to nearly 50%. Photoacoustic analysis on this phenomena was carried out for the first time. Through this study, we find that the ferroelectricity of the polymer additive plays the key role in the enhancement of the power conversion efficiency of the organic solar cell by suppressing the non-radiative recombination of charge transfer exciton more effectively.