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Investigation of channel mobility in AlGaN/GaN high-electron-mobility transistors
Chang, Sung-Jae,Kang, Hee-Sung,Lee, Jae-Hoon,Yang, Jie,Bhuiyan, Maruf,Jo, Young-Woo,Cui, Sharon,Lee, Jung-Hee,Ma, Tso-Ping Institute of Pure and Applied Physics 2016 Japanese Journal of Applied Physics Vol.55 No.4
<P>We have investigated the channel mobility in the gated region of a set of high-quality AlGaN/GaN high-electron-mobility transistors (HEMTs). The resistances in the contact, access, and gated regions were extracted from straightforward I-D(V-G) measurements on sets of HEMTs with four different gate-to-drain distances. By correcting for the effects of the contact and access resistances, much more accurate effective mobility curves in the gated region, compared to those reported in the past, have been obtained. The maximum effective mobility in that region has been found to be 1100cm(2)V(-1) s(-1) at carrier density n(s) = 7 x 10(12)cm(-2) at room temperature. We have extracted the mobility curves in a wide range of temperatures (80 to 520 K) and carrier concentrations (up to 1.3 x 10(13)cm(-2)). Our systematic measurements have revealed various dominant scattering mechanisms as the temperature and carrier concentration change. (C) 2016 The Japan Society of Applied Physics</P>
Liu Li-Wen,Chang Cheng-Ping,Lin Yu-Wen,Chu Wei-Ming 한국산업안전보건공단 산업안전보건연구원 2024 Safety and health at work Vol.15 No.2
Background Glove reuse poses risks, as chemicals can persist even after cleaning. Decontamination methods like thermal aeration, recommended by US OSHA, vary in effectiveness. Some studies show promising results, while others emphasize the importance of considering both permeation and tensile strength changes. This research advocates for informed glove reuse, emphasizing optimal thermal aeration temperatures and providing evidence to guide users in maintaining protection efficiency. Methods The investigation evaluated Neoprene and Nitrile gloves (22 mils). Permeation tests with toluene and acetone adhered to American Society for Testing Materials (ASTM) F739 standards. Decontamination optimization involved aeration at various temperatures. The experiment proceeded with a maximum of 22 re-exposure cycles. Tensile strength and elongation were assessed following ASTM D 412 protocols. Breakthrough time differences were statistically analyzed using t-test and ANOVA. Results At room temperature, glove residuals decreased, and standardized breakthrough time (SBT)2 was significantly lower than SBT1, indicating reduced protection. Higher temperature decontamination accelerated residual removal, with ΔSBT (SBT2/SBT1) exceeding 100%, signifying restored protection. Tensile tests showed stable neoprene properties postdecontamination. Results underscore thermal aeration's efficacy for gloves reuse, emphasizing temperature's pivotal role. Findings recommend meticulous management strategies, especially post-breakthrough, to uphold glove-protective performance. Conclusions Thermal aeration at 100°C for 1 hour proves effective, restoring protection without compromising glove strength. The study, covering twenty cycles, suggests safe glove reuse with proper decontamination, reducing costs significantly. However, limitations in chemical-glove combinations and exclusive focus on specific gloves caution against broad generalization. The absence of regulatory directives on glove reuse highlight the importance of informed selection and rigorous decontamination validation for workplace safety practices. Background Glove reuse poses risks, as chemicals can persist even after cleaning. Decontamination methods like thermal aeration, recommended by US OSHA, vary in effectiveness. Some studies show promising results, while others emphasize the importance of considering both permeation and tensile strength changes. This research advocates for informed glove reuse, emphasizing optimal thermal aeration temperatures and providing evidence to guide users in maintaining protection efficiency. Methods The investigation evaluated Neoprene and Nitrile gloves (22 mils). Permeation tests with toluene and acetone adhered to American Society for Testing Materials (ASTM) F739 standards. Decontamination optimization involved aeration at various temperatures. The experiment proceeded with a maximum of 22 re-exposure cycles. Tensile strength and elongation were assessed following ASTM D 412 protocols. Breakthrough time differences were statistically analyzed using t-test and ANOVA. Results At room temperature, glove residuals decreased, and standardized breakthrough time (SBT)2 was significantly lower than SBT1, indicating reduced protection. Higher temperature decontamination accelerated residual removal, with ΔSBT (SBT2/SBT1) exceeding 100%, signifying restored protection. Tensile tests showed stable neoprene properties postdecontamination. Results underscore thermal aeration's efficacy for gloves reuse, emphasizing temperature's pivotal role. Findings recommend meticulous management strategies, especially post-breakthrough, to uphold glove-protective performance. Conclusions Thermal aeration at 100°C for 1 hour proves effective, restoring protection without compromising glove strength. The study, covering twenty cycles, suggests safe glove reuse with proper decontamination, reducing costs significantly. However, limitations in chemical-glove combinations and exclusive focus on specific gloves caution against broad generalization. The absence of regulatory directives on glove reuse highlight the importance of informed selection and rigorous decontamination validation for workplace safety practices.
APPLICATIONS OF THE HILBERT-HUANG TRANSFORM ON THE NON-STATIONARY ASTRONOMICAL TIME SERIES
HU, CHIN-PING,CHOU, YI,YANG, TING-CHANG,SU, YI-HAO,HSIEH, HUNG-EN,LIN, CHING-PING,CHUANG, PO-SHENG,LIAO, NAI-HUI The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2
The development of time-frequency analysis techniques allow astronomers to successfully deal with the non-stationary time series that originate from unstable physical mechanisms. We applied a recently developed time-frequency analysis method, the Hilbert-Huang transform (HHT), to two non-stationary phenomena: the superorbital modulation in the high-mass X-ray binary SMC X-1 and the quasi-periodic oscillation (QPO) of the AGN RE J1034+396. From the analysis of SMC X-1, we obtained a Hilbert spectrum that shows more detailed information in both the time and frequency domains. Then, a phase-resolved analysis of both the spectra and the orbital profiles was presented. From the spectral analysis, we noticed that the iron line production is dominated by different regions of this binary system in different superorbital phases. Furthermore, a pre-eclipse dip lying at orbital phase ~0:6-0:85 was discovered during the superorbital transition state. We further applied the HHT to analyze the QPO of RE J1034+396. From the Hilbert spectrum and the O-C analysis results, we suggest that it is better to divide the evolution of the QPO into three epochs according to their different periodicities. The correlations between the QPO periods and corresponding fluxes were also different in these three epochs. The change in periodicity and the relationships could be interpreted as the change in oscillation mode based on the diskoseismology model.
Sohng, Hee Yon,Kuniyuki, Alan,Edelson, Jane,Weir, Rosy Chang,Song, Hui,Tu, Shin-Ping Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.12
Background: Understanding and enhancing change capabilities, including Practice Adaptive Reserve (PAR), of Community Health Centers (CHCs) may mitigate cancer-related health disparities. Materials and Methods: Using stratified random sampling, we recruited 232 staff from seven CHCs serving Asian Pacific Islander communities to complete a self-administered survey. We performed multilevel regression analyses to examine PAR composite scores by CHC, position type, and number of years worked at their clinic. Results: The mean PAR score was 0.7 (s.d. 0.14). Higher scores were associated with a greater perceived likelihood that clinic staff would participate in an evidence-based intervention (EBI). Constructs such as communication, clinic flow, sensemaking, change valence, and resource availability were positively associated with EBI implementation or trended toward significance. Conclusions: PAR scores are positively associated with perceived likelihood of clinic staff participation in cancer screening EBI. Future research is needed to determine PAR levels most conducive to implementing change and to developing interventions that enhance Adaptive Reserve.
A Study on the Development of Rotary Ultrasonic Machining Spindle
Chang-Ping Li(이상평),Min-Yeop Kim(김민엽),Jong-Kweon Park(박종권),Tae-Jo Ko(고태조) 한국기계가공학회 2015 한국기계가공학회지 Vol.14 No.4
Ultrasonic machining (USM) has been considered a new, cutting-edge technology that presents no heating or electrochemical effects, with low surface damage and small residual stresses on brittle workpieces. However, nowadays, many researchers are paying careful attention to the disadvantages of USM, such as low productivity and tool wear. On the other hand, in this study, a high-performance rotary ultrasonic drilling (RUD) spindle is designed and assembled. In this system, the core technology is the design of an ultrasonic vibration horn for the spindle using finite element analysis (FEA). The maximum spindle speed of RUM is 9,600 rpm, and the highest harmonic displacement is 5.4 μm noted at the frequency of 40 ㎑. Through various drilling experiments on glass workpieces using a CVD diamond-coated drill, the cutting force and cracking of the hole entrance and exit side in the glass have been greatly reduced by this system.
Cases Studies on Total Productive Management and Competitive Advantages
(Chang Chung Li),(Ping Chen Tsai) 한국품질경영학회 2001 The Asian Journal on Quality Vol.2 No.1
The purpose of business strategy is to achieve competitive advantages which includes higher efficiency, better quality, more innovation and faster customer response. In other words, The business strategy is to build unique capability of lower cost and/or differentiation. In production aspect, unique capability means better production power with better performance at 3M(Man, Machine, Material) of input and PQCDSM (Product, Quality, Cost, Delivery, Safety, Moral) from output. The Total Productive management (TPM), a series of improvement activities focused on reduction of equipment loss, is a tool to establish business competitive advantages. In this paper, several domestic companies who won the Japan TPM Award have been studied. It is found that there is a strong cause-effect relationship between TPM and competitive advantages because. 1. TPM can change employees mindset effectively. 2. TPM can upgrade employees capabilities. 3. TPM can lead to excellent productivity.