Transcutaneous Repetitive Phrenic Nerve Stimulation in Healthy Adults

Inclusion Criteria: * Koreans who speak Korean as their mother tongue, aged 19 or older and younger than 40. * Those who understood the purpose and procedure of this study and voluntarily participated with consent. Exclusion Criteria: 1. \- Those who have any neuromuscular disease. \- Those whom abnormal findings are observed on a neurological examination. e.g.) Cases with abnormal findings in peripheral motor nerve (median nerve) and sensory nerve (sural nerve) conduction studies performed in screening. e.g.) People who have been diagnosed with a neuromuscular junctional diseases such as myasthenia gravis or receiving related treatment. 2. In the case of implantable electronic medical devices such as pacemakers, implantable cardioverter defibrillators (ICDs), and spinal cord stimulation devices. 3. Those who have any history of radiation therapy or chemotherapy for cancer within a year. 4. People who have a history of cardiovascular or cerebrovascular disease or lung disease within 6 months. 5. Those who have been diagnosed with a psychiatric/neurological problem or taking related medications that may affect electrophysiological study. 6. Those who are pregnant or may be pregnant. 7. Those who are judged to lack the cognitive ability to understand the explanation of the purpose and procedure of this study. 8. Those whom the researchers judge for other reasons to be inappropriate to participate in this study.