No.0371520 A device to protect contamination in the pipe taking underground water No.0599853 A underground heat exchanger to prevent erosion
No.0395026 A compensating device and its compensating way for vaporized temperature of heat pump No.0599854 A contractile heat type of heat pump unit using geothermy
No.0403017 A cooling device and its cooling method for the inverter of heat pumps No.0628986 A cooling and heating system and its controlling method using underground water
No.0530259 A geothermal heat pump unit in Geothermal contraction type No. 0648300 A heat pump type of cooling and heating device
No.0557460 A geothermal heat pump system No. 0659461 A geothermal heat exchanger in which an underground water supply device is attached