Core temperature should be monitored under general anesthesia. Recently developed 3M Spoton skin temeprature which is applied on temporal artery is correlated with core temperature measure by esophageal prove in several studies. Conventional skin temperature over carotid artery is also correlated with core temperature in several studies. The purpose of this study is comparing 3 methods of temperature monitoring. First, conventional core temperature measure by esophageal stethoscope. Second, 3M Spoton applying on temporal artery. Third, 3M Spoton applying on carotid artery

Core temperature should be monitored under general anesthesia. Because patients are prone to hypothermia during surgery. Conventional core temperature is monitored at esophagus, rectum, nasopharynx. But some of them are invasive and impossible in sometimes. Recently developed 3M Spoton skin temeprature which is applied on temporal artery is correlated with core temperature measured by esophageal prove in several studies. Its mechanism is making zero heat flux on skin applied. But it also cannot apply in head or facial surgery. Other studies showed conventional skin temperature over carotid artery is also correlated with core temperature. The investigators hypothesized using Spoton on carotid artery could be alternative method measuring core temperature. The purpose of this study is comparing 3 methods of temperature monitoring. First, conventional core temperature measure by esophageal stethoscope. Second, 3M Spoton applying on temporal artery. Third, 3M Spoton applying on carotid artery

Inclusion Criteria:

• Age 19~60 years old
• Who need surgery more than 2 hours under general anesthesia
• American Society of Anesthesiologists physical status 1 or 2

Exclusion Criteria:

• Body mass index < 35
• Head and neck surgery
• Patients with fever > 38'C
• History of malignant hyperthermia

Patients who scheduled surgery more than 2 hours under general anesthesia. Who need esophageal temperature monitoring for routine monitoring.