Thermal preferences and cognitive performance estimation via user's physiological responses

This study investigated the relationship between occupants' thermal sensation, physiological responses, and cognitive performance to quantify the priorities of the selected physiological responses for optimal productivity. In order to quantify variables for optimal productivity estimation, this study considered the following factors: 1. Local body skin temperature as an occupant's physiological responses; 2. Participants' individual factors such as gender; 3. Cognitive performance in operation span task; 4. Environmental data such as indoor temperature, wind velocity, CO2 level and indoor humidity; 5. Individual ratings of subjective thermal sensation. A series of human experiments were conducted to collect physiological responses and cognitive performance in a different room temperature conditions. The skin temperatures and environmental data were recorded in every minutes, and thermal sensation was surveyed by the Likert 7 point scale questionnaires. The operation span (OSPAN) task was used to measure working memory as a cognitive performance for occupant's productivity. Total 39 participants' data was collected for comparative analysis. The results revealed significant correlations between overall thermal sensation and local body skin temperatures. Also, the OSPAN score showed that it has a significant correlation with indoor temperature, thermal sensation as well as physiological responses. The OSPAN results were higher when indoor temperature was relatively low or when participant's thermal perception was either slightly cool or cool. Most local body skin temperatures were negatively correlated with the cognitive test scores, therefore it was concluded that a little low temperature has a significant impact to promote occupant's productivity. This study also determined the priority of local skin temperatures and gender by their impact to estimate the occupant's cognitive performance

Investigation of SiO2 Etch Characteristics by C6F6/Ar/O2 Plasmas Generated Using Inductively Coupled Plasma and Capacitively Coupled Plasma

The etching properties of C6F6/Ar/O2 in both an inductively coupled plasma (ICP) system and a capacitively coupled plasma (CCP) system were evaluated to investigate the effects of high C/F ratio of perfluorocarbon (PFC) gas on the etch characteristics of SiO2. When the SiO2 masked with ACL was etched with C6F6, for the CCP system, even though the etch selectivity was very high (20 ~ infinite), due to the heavy-ion bombardment possibly caused by the less dissociated high-mass ions from C6F6, tapered SiO2 etch profiles were observed. In the case of the ICP system, due to the higher dissociation of C6F6 and O2 compared to the CCP system, the etching of SiO2 required a much lower ratio of O2/C6F6 (~1.0) while showing a higher maximum SiO2 etch rate (~400 nm/min) and a lower etch selectivity (~6.5) compared with the CCP system. For the ICP etching, even though the etch selectivity was much lower than that by the CCP etching, due to less heavy-mass-ion bombardment in addition to an adequate fluorocarbon layer formation on the substrate caused by heavily dissociated species, highly anisotropic SiO2 etch profiles could be obtained at the optimized condition of the O2/C6F6 ratio (~1.0)