## 1 Introduction
In addition, they reported that the \(\alpha\)-wave frequencies increased and stress sensitivity decreased in the environment in which the subjects felt comfortable. Moreover, [PERSON] et al. [23] evaluated EEG activity according to the complexity of the terrain during driving by using a driving simulation. They reported that the driver's condition could be continuously monitored by the changes in EEGs to immediately detect overload/unload and provide feedback to the driver to take countermeasures and prevent fatal errors. [PERSON] et al. [24] developed a short-term driving condition prediction model by studying the characteristics of the driver's EEGs, assuming the cause of traffic accidents and estimating the driving condition. In addition, [PERSON] et al. [25] identified the level of drowsiness by examining the driver's EEGs and proposed a new model for detecting driver drowsiness. An average accuracy of 98% was achieved by verifying and classifying drowsiness in drivers by tracking the changes in the \(\alpha\)-wave activity and extracting shapes from physiological signals. Furthermore, [PERSON] et al. [26] studied the driver fatigue state in a low-voltage and low-oxygen environment to monitor psychological parameters through EEG measurements. They provided basic data on the theory and inspection for the design of the driving fatigue-warning device and their result was considerably significant to the development of a driver's fatigue detection system. In addition, concentration and thermal comfort of subjects were investigated by using subjective questionnaires and measurement of biosignals in various indoor environments [27]. They reported that the stress was low in an appropriate indoor environment, and the concentration was increased as activity of the alpha wave increased. Besides, LF/HF decreased, and SDNN and RMSSD increased, under a comfortable environment. Various studies have been conducted on biosignals in humans in rest conditions. [PERSON] et al. [28] examined the effect of music on EEGs during sleep. During one week, the subjects listened to music for 30 min before sleep. As a result, the spectral density increased in the LF range (0-3 Hz), whereas it decreased in the HF range, of more than 12 Hz, after listening to music. Therefore, they concluded that the quality of sleep was improved when music was used. [PERSON] et al. [29] investigated the effect of indoor temperature on the sleep quality and the thermal comfort of subjects. EEG analysis showed that it takes longer for the subject to fall asleep at an environment temperature of 30 \({}^{\circ}\)C than at 26 \({}^{\circ}\)C. Moreover, they reported that the duration of the slow-wave sleep was shorter when the room temperature was outside the neutral range. In addition, various experiments related to EEG analysis in resting condition were also conducted. [PERSON] and [PERSON] [30] analyzed eyes open and closed during rest to examine the difference in EEG responses between young and older people. Their results indicated that elderly maintained the responsiveness of the energy system, compared to young people, and maintained their perception and cognitive abilities by utilizing additional focus brain activity in the resting condition. [PERSON] et al. [31] and [PERSON] [32] confirmed that the \(\theta\)-wave activity in the rest state was related to reinforcement learning, and the difference in compensation sensitivity explained this relationship. Additionally, [PERSON] et al. [33] and [PERSON] et al. [34] reported that the environment affected human sleep and awakening, which affected the body's thermal rhythm. They also mentioned that it is necessary to analyze the thermal comfort through appropriate control of the ambient and skin surface temperatures. Several studies have been conducted on the relationship between the thermal comfort of the human body under various environments.