Over the past decade, the number of car owners has been steadily rising, leading to a significant increase in the amount of time spent inside cars. As a result, there has been a greater focus placed on the impact of indoor air quality of new cars on drivers and passengers. There has also been a growing awareness among consumers of environmental and health issues such as the odor and indoor air quality of new cars. However, Korea currently only regulates eight compounds according to the indoor air quality management standards for new cars, and there is no test method that reflects the Korean climate. Two domestic gas-powered cars, one imported gas-powered car, and two domestic electric cars were tested under the following conditions: 1) 25oC, 50% RH; 2) 25oC, 50% R.H, solar load (400 ± 50 W/m2); and 3) 60oC, 10% R.H. The results of the 25oC condition met the indoor air quality management standards for new cars by the Ministry of Land, Infrastructure and Transport. Additionally, it was confirmed that the higher the test temperature, the higher the emission of VOCs from the car interior. VOC emissions reached 761.1 μg/m3, and the TVOC concentration was 308,241.4 μg/m3. The odor of new cars increased from a dilution factor of 10 to 208. Two out of five cars exceeded the emission standards of the Ministry of Environment’s Malodor Prevention Act. An odor activity value (OAV) analysis confirmed that acetaldehyde was the highest contributor to odors. The TVOC concentration exceeded the domestic indoor air quality standards for multi-use facilities (1,000 μg/m3). The eight pollutants covered under TVOC management accounted for about 1~6%, while other pollutants were found to account for over 90%. Further studies should expand and review objective indicators that can best represent the indoor air quality of new cars.

This study presents a seismic fragility assessment methodology incorporating the cumulative damage effects of repeated seismic loading on structures. Conventional seismic fragility assessment methods typically focus on single earthquakes across multiple structures; however, seismic events often occur in sequences, with each event adding cumulative damage that can amplify the overall damage. Ignoring the effects of repeated earthquakes in fragility assessments may lead to underestimating seismic risk. This study proposes a simplified but efficient fragility assessment method that accounts for repeated earthquake effects using probabilistic combinations of each damage state. This procedure applied the capacity spectrum method to consider capacity degradation from displacement caused by prior earthquakes. Applying various earthquake scenarios, this study analyzes the effects of damage accumulation from earthquake occurrence sequences, structural behavior types, and seismic design levels on the fragility of structures under repeated earthquake events.