Browsing by Author "Shih, Hui-Ya"

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Development of regenerative dye impregnated mesoporous silica materials for assessing exposure to ammonia
(2012)
Chang, Yu-Chang
;
Bai, Hsunling
;
Chiang, Hsueh-Shih
;
Karthik, Mani
;
Li, Shou-Nan
The mesostructured materials MCM-41 and SBA-15 were studied as possible supports of bromocresol green (BG) dye impregnation for the ammonia gas detection because of their large surface area, high regenerative property, and high thermal stability. X-ray diffraction, transmission electron microscopy, scanning electron microscope, and N-2 adsorption analysis were used to characterize the prepared materials. These materials could sense ammonia via visible color change from yellowish-orange to blue color. The color change process of the nanostructured materials was fully reversible during 10 cyclic tests. The results indicated that the ammonia absorption responses of the two nanostructured materials were both very sensitive, and high linear correlation and high precision were achieved. As the gaseous ammonia concentrations were 50 and 5 ppmv, the response times for the SBA-15/BG were only 1 and 5 min, respectively. Moreover, the BG dye-impregnated SBA-15 was less affected by the variation in the relative humidity. It also had faster response for the detection of NH3, as well as lower manufacturing price as compared to that of the dye-impregnated MCM-41. Such feature enables SBA-15/BG to be a very promising material for the detection of ammonia gas. Implications: The detector tube is a convenient ambient ammonia detection device. However, almost all the commercial detector tubes can be used once only, which not only increases the purchase cost but also produces lots of waste. In this study, we developed two sensing materials that are sensitive for repeated usage. The two mesoporous silica-based materials, MCM-41 and SBA-15, are impregnated by an organic dye of bromocresol green to induce color change behavior that can be easily observed by the naked eye, and it is concluded that dye-impregnated SBA-15/BG is a very promising material for the detection of ammonia gas.
Dispersion of gas pollutant in a fan-filter-unit (FFU) cleanroom
(2007-05-01)
Chen, Sheng-Chieh
;
Tsai, Chuen-Jinn
;
Li, Shou-Nan
;
Shih, Hui-Ya
;
環境工程研究所
. Numerical simulation and. experimental measurement of flow and concentration fields in a working fan-filter-unit (FFU) cleanroom have been conaucted in this study. The purpose,of the study is to find out the unsteady concentration distribution of a leaking gas pollutant. The standard K-e model was used for the simulation of the flow field. To obtain the gas concentration field, SF6 gas with a certain concentration was released as a simulated leaking source from a valve manifold box (VMB) for 5 or 10 min, respectively. Three Fourier transform infrared spectrometers (FTIRs) were simultaneously used to measure the spatial and temporal distributions of SF6 concentrations. The measured data were then compared with the numerical results and the agreement is seen to be quite good. From the numerical results, the pollutant hot spots, peak pollutant concentration at the end of leaking, and time taken for the concentration to reduce to near background level are obtained. (c) 2006 Elsevier Ltd. All rights reserved.
Simulation and testing of pollutant dispersion during preventive maintenance in a cleanroom
(2009-12-01)
Shih, Hui-Ya
;
Huang, Shih-Hsuan
;
Li, Shou-Nan
;
Chen, Sheng-Chieh
;
Tsai, Chuen-Jinn
Sulfur hexafluoride (SF(6)) of >99.9% purity was artificially released to simulate the emission sources in the etching-thin film area of a working cleanroom in a semiconductor fab at the rate of 492 g/h. Three mobile Fourier transform infrared spectrometers (FTIRs, detection limit: 10 ppb) were used simultaneously to measure the real time SF6 concentrations at different locations of the cleanroom. A three-dimensional numerical model was also used to predict the unsteady gas concentration distribution and the results were compared with the experimental data. Due to high dilution of the pollutant in the cleanroom, it is found that the current gas sensors may not be sensitive enough and a better monitoring system and strategy is needed to protect workers from injury and to ensure good product yield. After comparison with the validated numerical results. the well-mixed model is found to predict the peak pollutant concentrations within a reasonable range which is 0.34-1.33 times the experimental values except when the monitored distance is very close to the release point. The well-mixed model is shown to be capable of predicting a reasonable attainable maximum concentration once a pollutant leaks in the cleanroom. (C) 2009 Elsevier Ltd. All rights reserved.
Spatial and Temporal Distributions of a Gaseous Pollutant During Simulated Preventive Maintenance and Pipe Leaking Events in a Working Cleanroom
(2009-08-01)
Huang, Shih-Hsuan
;
Shih, Hui-Ya
;
Li, Shou-Nan
;
Chen, Sheng-Chieh
;
Tsai, Chuen-Jinn
Sulfur hexafluoride (SF(6)) of > 99.9% in purity was artificially released to simulate the emission sources in the etching/thin-film area of a working cleanroom in a semiconductor fab at the rate of 492 g/h. The temporal and spatial dispersion patterns of the gas pollutant were studied during the simulated preventive maintenance ( PM) and pipe leaking exhaust events experimentally and numerically. Three mobile Fourier transform infrared spectrometers (FTIRs, detection limit: 10 ppb) were used simultaneously to measure the real time SF(6) concentrations in different locations of the etching/thin-film area of the cleanroom. An additional open-path FTIR with very low detection limit of 0.4 ppb was installed before the recirculation duct in the lithography area to monitor if the pollutant drifted from the etching/thin-film area to the lithography area. The results show that the 3-D numerical model predicts the unsteady gas concentration accurately in both the peak concentration and the time required to reach the peak concentration. Due to high dilution of the pollutant in the cleanroom, the current gas sensors may not be sensitive enough and a better monitoring system and strategy is needed to protectworkers from injury and ensure good product yield. The well-mixed model predicts the peak pollutant concentrations within a reasonable range which is 0.34-1.33 times the experimental values except when the monitored distance is very close to the release point. Although it is not able to predict the time required to reach the peak concentration and the time for the concentration to drop below a small level, the simple well-mixed model can be used to obtain an estimation of the peak concentration quickly when the emission rate and the ventilation condition of the cleanroom are different than the current study.