Tae H Cho

41052030, Aug 8, 1978

Jan 11, 1977

5/758396

Tae Han Cho - Gaithersburg MD

A63B 6938

273 29A

A tennis trainer includes a generally L-shaped arm having a ball holder at one end and pivotally engaged to a support at the other. Impact against the ball in a direction axially along the ball-supporting section of the arm is initially absorbed by a resilient section of the other section of the arm. A housing on the support includes a slot through which the arm extends and a rotatable cylinder to which the arm is secured. Bias springs oppose rotation of the cylinder and hence the arm. The housing is mountable upside down to permit the trainer to be used for back hand practice or for left handed fore hand practice. Various bending of the arm and vertical positioning of the support permits the ball to be positioned at various heights and positions.

42548438, Mar 10, 1981

Jul 20, 1979

6/059130

Joon H. Han - Silver Spring MD
Tae H. Cho - Gaithersburg MD

B60K 100

180165

An electrically powered vehicle having a bank of batteries supplying electricity to an electric motor driving wheels of the vehicle includes a whirl ventilator system, a clutch system and an automatically operated, engine-generator unit for recharging the batteries. The whirl ventilator system includes housings to produce a whirling air flow rotating a fan to drive an alternator such that air flow from movement of the vehicle generates electricity to charge the batteries. The clutch system includes a clutch mechanism coupling a drive shaft and a driven shaft to impart a driving force to the wheels when the drive shaft is rotated faster than the driven shaft and to couple the driven shaft with a flywheel when the driven shaft is rotating faster than the drive shaft, the flywheel driving an alternator such that momentum of the vehicle causes the alternator to charge the batteries. The automatically operated, engine-generator unit is started to charge the batteries when the level of charge therein has dropped below a predetermined level and stopped when the charge level reaches a second predetermined level.