Sung‐Jun Yoo

Abstract Computer‐simulated persons (CSPs) with respiratory systems have been developed for microclimate analysis around the human body and inhalation exposure analysis, for detailed assessment of comfort and health risks in indoor spaces. This study examined and validated the prediction accuracy of a CSP, for precise estimation of indoor environmental quality (IEQ). The flow‐field prediction accuracy was thoroughly examined in a grid analysis using the CSP and a thermal manikin for benchmarking. The model incorporated unsteady breathing and human postural sway, and assessed their impact on the microclimate around the human body. The numerically estimated flow field was validated using experimental particle image velocimetry (PIV) data, with a detailed grid independence test. Considering the practical use of the respiratory tract model for the inhalation exposure risk assessment, the prediction accuracy of particle transport and deposition analysis was examined using previously published in vivo experimental results. This analysis revealed that the impact of transient breathing and body vibrations on the reproduction of the thermal plume around the human body is quite weak; consequently, these conditions can be ignored from the macroscopic perspective of indoor airflow analysis.

The use of metalworking fluids during machining can generate oil mist and endanger the health of workers. In order to study the characteristics and emission laws of oil mist generated by machining, this study constructed a test bench to simulate the turning process. Parameters affecting the oil mist generated in the minimum quantity lubrication (MQL) mode and flood cooling mode were studied by means of single-factor experiments, and the formation mechanisms of oil mist were analyzed. The results show that the oil mist generated by the MQL system has two main sources, the initial escape of oil mist into the air and the evaporation/condensation of oil mist. The centrifugation has almost no effect on oil mist formation in the MQL mode. The mass concentration of oil mist generated by the MQL system is proportional to the cutting oil flow rate. When the work-piece is at room temperature, increasing the air supply pressure and nozzle distance, increases the oil mist mass concentration. For the flood cooling mode, the concentration of centrifugal aerosol is linearly and positively correlated with the relative centrifugal force generated by the work-piece, and the coefficient of determination (R2) is above 0.97. The oil mist mass concentrations in MQL mode is 8.33 mg/m3~ 305.88 mg/m3. The MMD and SMD are 0.74 µm to 4.42 µm and 0.31 µm to 2.14 µm, respectively. The oil mist mass concentrations in flood cooling mode is 0.2 mg/m3~ 22.42 mg/m3. The MMD and SMD are 1.81 µm to 6.58 µm and 0.45 µm to 5.13 µm, respectively.

Indoor environmental quality, e.g. air quality and thermal environments, has a potential impact on residents in indoors. Development of a computer simulated person (CSP) for indoor computational fluid dynamics (CFD) simulation can contribute to the improvement of design and prediction method regarding the interaction between indoor air/thermal environmental factors and human responses. In this study, a CSP integrated with a virtual airway was developed and used to estimate inhalation exposure in an indoor environment. The virtual airway is a numerical respiratory tract model for CFD simulation that reproduces detailed geometry from the nasal/oral cavity to the bronchial tubes by way of the trachea. Physiologically based pharmacokinetic (PBPK)-CFD hybrid analysis is also integrated into the CSP. Through the coupled simulation of PBPK-CFD-CSP analysis, inhalation exposure under steady state conditions where formaldehyde was emitted from floor material was analysed and respiratory tissue doses and their distributions of inhaled contaminants are discussed quantitatively.