David H Cho

US Patent:

20070040529, Feb 22, 2007

Filed:

Aug 19, 2005

Appl. No.:

11/206943

Inventors:

Takashi Takebayashi - Irvine CA, US
David Cho - Anaheim CA, US
Pavel Tomov - Irvine CA, US
Dipen Gokhale - Cerritos CA, US

Assignee:

SMC Corporation of America - Indianapolis IN

International Classification:

G05B 19/40

US Classification:

318685000

Abstract:

A stepping motor is driven in both closed-loop and open-loop modes while initiating microstepping after a predetermined threshold velocity has been reached. A feedback device such as an encoder is mounted on the stepping motor shaft and the encoder keeps track of the mechanical position of the rotor. Based on feedback from the encoder, stator phases are activated to maintain a 90 phase advance and produce maximum torque. A lead angle compensation technique is used to advance the motor lead angle, to allow for the excitation currents to reach maximum even at higher speeds. The stepping motor controller employs this strategy in order to produce maximum torque across a wide range of motor speeds and actuator motions.

US Patent:

58326731, Nov 10, 1998

Filed:

May 30, 1996

Appl. No.:

8/655748

Inventors:

David S. Cho - Cypress CA

Assignee:

Atlantic Richfield Company - Los Angeles CA

International Classification:

E02D 2914

US Classification:

52 19

Abstract:

A seal and extender assembly which prevents surface water and other environmental liquids from inadvertently entering a sump, such as one used in a gasoline service station. The seal assembly includes an extender and a cover. The extender defines a channel and has a first end and a second end, the first end has a larger diameter than the diameter of the second end, the first end is secured to the sump adjacent the access port. The cover has a top surface and a perimeter surface, the top surface covers the access port and the perimeter surface secures to the second end of the extender.

US Patent:

48846627, Dec 5, 1989

Filed:

Mar 30, 1988

Appl. No.:

7/175106

Inventors:

David Cho - Los Angeles CA
Richard M. Steckler - Los Angeles CA

Assignee:

Carousel Commons - Beverly Hills CA

International Classification:

E04H 304

US Classification:

186 36

Abstract:

A driver interaction center, and a method of operating such a center, which includes a driver service dispensation structure, having a plurality of collection stations for dispensing services, and a plurality of driveways, each of which is arrayed adjacent to at least one of the collection stations and which is directionally oriented for tandem collection of the services at the driver's side of vehicles such that drivers need not have to leave their seats to collect the services. Each of the driveways further defines a drive-thru periphery that is situated along the driver's side of vehicles as the vehicles proceed along the given driveway. The driver interaction center can be a food court center, a bank center, a photography center, as well as any of a number of other centers which provide goods or services on a drive-thru basis or have a combination of counter sevice and drive-thru service. In "left-side-driver" countries, such as the United States, each of the driveways is a "right-turn-left-side-driver-specific" driveway. Conversely, in "right-side-driver" countries, such as Great Britain and Japan, each of the driveways is a "left-turn-right-side-driver-specific" driveway.