Patents by Inventor Dong Kwan Ma
Dong Kwan Ma has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 7134379Abstract: Disclosed is a gas cylinder, for improving sealing characteristics of the gas cylinder and improving convenience in manufacturing, including: a valve having a gas opening/closing pin at a through hole in its center, for intermittently passing a gas, and additionally having a valve dividing body seated on a groove approximately in a lower part of the through hole; a spindle to an upper inside of which the valve is inserted; and a piston inserted to an inside of an open cylinder of the spindle, and having, a step threshold formed at a predetermined distance from an upper end, to which an O-ring for maintaining sealing is fit, and having another step threshold ranging from a lower side of the step threshold to a lower end on an inner lateral surface of the piston, to which an O-ring is fit.Type: GrantFiled: June 27, 2003Date of Patent: November 14, 2006Inventors: Young Sang Jeon, Dong Kwan Ma, Ki Cheol Lee
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Publication number: 20040079854Abstract: A column unit is disclosed, in which a guide sleeve is adhered to the external surface of a spindle by an adhesive for metal, thereby allowing the spindle to stably perform a long stroke. The column unit provided with a spindle that moves up and down in a base tube to adjust the height of chair or table includes a cylindrical shaped guide sleeve fixed onto the external surface of the spindle from an upper portion of the spindle to a height lower than its lower portion, moving up and down along with the spindle, and an adhesive layer applied between the guide sleeve and the spindle to fixably adhere the guide sleeve to the spindle. Therefore, the stroke length of the spindle can stably be increased and the adhesive is simply used to adhere the guide sleeve to the spindle, thereby saving the cost for mass production.Type: ApplicationFiled: October 15, 2003Publication date: April 29, 2004Inventors: Dong Kwan Ma, Gi Jong Kim
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Publication number: 20040061367Abstract: Disclosed is a gas cylinder, for improving sealing characteristics of the gas cylinder and improving convenience in manufacturing, including: a valve having a gas opening/closing pin at a through hole in its center, for intermittently passing a gas, and additionally having a valve dividing body seated on a groove approximately in a lower part of the through hole; a spindle to an upper inside of which the valve is inserted; and a piston inserted to an inside of an open cylinder of the spindle, and having, a step threshold formed at a predetermined distance from an upper end, to which an O-ring for maintaining sealing is fit, and having another step threshold ranging from a lower side of the step threshold to a lower end on an inner lateral surface of the piston, to which an O-ring is fit.Type: ApplicationFiled: June 27, 2003Publication date: April 1, 2004Inventors: Young Sang Jeon, Dong Kwan Ma, Ki Cheol Lee
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Patent number: 6533084Abstract: The present invention relates to a speed reducing device of a gas spring device. The piston is slidably moved in the cylinder in the state the piston is adhered to the inner wall surface of the cylinder, and a cutting recess is formed on the outer peripheral surface of the cylinder to easily move the gas in first and second chambers. A concentric gas passage is formed on the surface of the piston which makes contact with the upper washer, and includes another concentric gas passage. An inlet and outlet of the gas passage is opened towards the outer peripheral surface of the piston. A concentric gas passage is formed on the surface of the piston which makes contact with the under washer. The inlet and outlet of the gas passages is opened towards the bottom surface of an annular recess. The gas passage is connected by an axial recess which penetrates the piston.Type: GrantFiled: May 7, 2001Date of Patent: March 18, 2003Assignee: Samhongsa Co., Ltd.Inventor: Dong Kwan Ma
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Publication number: 20020162714Abstract: The present invention relates a speed reducing device of a gas spring device, and it is an object of the present invention to improve the structure of a piston which is an element of the speed reducing device, thereby to improve the shielding preciseness of a gas moving passage and to easily manufacture the piston. The piston according to the present invention is slidably moved in the cylinder in the state the piston is adhered to the inner wall surface 110a of the cylinder, and a cutting recess is formed on the outer peripheral surface of the cylinder to easily move the gas in first and second chambers. A concentric gas passage is formed on the surface of the piston which makes contact with the upper washer, and includes another concentric gas passage. An inlet and outlet of the gas passage is opened towards the outer peripheral surface of the piston. A concentric gas passage is formed on the surface of the piston which makes contact with the under washer.Type: ApplicationFiled: May 7, 2001Publication date: November 7, 2002Inventor: Dong Kwan Ma
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Patent number: 6474619Abstract: The present invention relates to a tube guide for a column unit, and more particularly to a tube guide for a column unit which can smoothly move a spindle upward and downward by forming a plurality of ribs on the inside surface of the tube guide which guides a spindle which has a multilateral cross-section and which can smoothly accomplish the broaching. The tube guide has a hexagonal inside surface. Two inside ribs are formed on each surface along the axial direction. Since the upward and downward movements of the spindle reduce the contacting area, the frictional force is remarkably reduced and the spindle is smoothly moved upward and downward. Further, only one surface of the inside rib needs to be broached, the broaching area is remarkably reduced.Type: GrantFiled: September 12, 2001Date of Patent: November 5, 2002Assignee: Samhongsa Co., Ltd.Inventor: Dong Kwan Ma
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Patent number: 6439662Abstract: A spindle base which constitutes a height regulating device of a chair, and it is an object of the present invention to improve the corrosion resistance, the abrasion resistance, the fatigue strength, and the reverse bending stress of the spindle body by coating a nitration layer of a predetermined thickness on the inner and outer surfaces of the spindle base. A height regulating device gas comprises a spindle base, a cylinder formed in the spindle base, a piston slidably moved in the cylinder, and a spindle having a piston rod having one end connected to the piston. The other end of the piston rod is fixed to one end of an outer case and the spindle is moved upward and downward through the outer case based on the piston rod and the outer case. The spindle base is comprised of a metal and nitration layers are formed on the inner and outer surface of the metal.Type: GrantFiled: May 7, 2001Date of Patent: August 27, 2002Assignee: Samhongsa Co., Ltd.Inventor: Dong Kwan Ma
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Patent number: 6371421Abstract: The present invention relates to a height-controlling device of a swivel chair. An objective of this invention is to prevent the detachment of components which are fitted to the end of a piston rod of a cylinder, resulting in the improvement of work conditions. The height-controlling device of the present invention is comprised of an elastic body 620, bearing supports 42 and 44, and a ball bearing 50 which are fitted to the end of a piston rod 610 of a cylinder 12; and a retaining washer 1 which is fixed to the piston rod and prevents the detachment of the elastic body, the bearing supports and the ball bearing component from the piston rod. Alternatively, the height-controlling device of the present invention is comprised of an elastic body 620 and a bearing support 42 which are fitted to the end of a piston rod 610 of a cylinder 12; and a thrust bearing 500 which is fixed to the piston rod and functions as both the bearing support 44 and the ball bearing component 50.Type: GrantFiled: August 5, 1998Date of Patent: April 16, 2002Assignee: Samhongsa Co., Ltd.Inventors: Dong Kwan Ma, Young Ki Yoon
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Publication number: 20010052720Abstract: The present invention relates to a spindle base which constitutes a height regulating device of a chair or the like, and it is an object of the present invention to improve the corrosion resistance, the abrasion resistance, the fatigue strength, and the reverse bending stress of the spindle body by coating a nitration layer of a predetermined thickness on the inner and outer surfaces of the spindle base. A height regulating device gas comprises a spindle base, a cylinder formed in the spindle base, a piston slidably moved in the cylinder, and a spindle having a piston rod having one end connected to the piston. The other end of the piston rod is fixed to one end of an outer case and the spindle is moved upward and downward through the outer case based on the piston rod and the outer case. The spindle base is comprised of a metal and nitration layers are formed on the inner and outer surface of the metal.Type: ApplicationFiled: May 7, 2001Publication date: December 20, 2001Inventor: Dong Kwan Ma