Patents by Inventor Chang Y. Choo

Chang Y. Choo 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).

  • Publication number: 20120140940
    Abstract: An acoustic control device for generating a pseudo echo signal by filtering an input remote speaker signal by using a plurality of adaptive filters and controlling the adaptive filters to perform filtering based on filter coefficients generates an error signal by subtracting a pseudo echo signal from an input nearby speaker signal, determines a convergence state of the filter coefficient based on the error signal, and controls the width of data input to the adaptive filter when the filter coefficient is determined to be converged
    Type: Application
    Filed: August 24, 2011
    Publication date: June 7, 2012
    Applicant: Electronics and Telecommunications Research Institute
    Inventors: In Ki HWANG, Chang Y. CHOO, Do Young KIM, Byung Sun LEE
  • Publication number: 20120140939
    Abstract: An acoustic echo cancellation device for generating a pseudo echo signal by filtering an input remote speaker signal based on a plurality of adaptive filters and controlling the adaptive filters to filter the same based on a filter coefficient. The acoustic echo cancellation device generates an error signal by subtracting the pseudo echo signal from a nearby speaker signal, determines a convergence state of the filter coefficient based on the error signal, and sets at least one filter coefficient with a previously used value to stop the operation for calculating new values for the corresponding filter coefficients when the filter coefficient is determined to be converged.
    Type: Application
    Filed: August 24, 2011
    Publication date: June 7, 2012
    Applicant: Electronics and Telecommunications Research Institute
    Inventors: In Ki HWANG, Chang Y. CHOO, Do Young KIM, Byung Sun LEE
  • Patent number: 6621864
    Abstract: A video decoding and display system uses temporal post-processing to smooth motion in a displayed moving image. The temporal post-processing uses motion vectors each of which indicates visually similar areas, in first and second frames to generate interpolated motion vectors which match areas in an interpolated frame to visually similar areas in the first and second frames. In one embodiment, each component of each motion vector is divided by two and used to generate an interpolated frame half way between the first and second frames. Display of the first and second frames are delayed so that the interpolated frame is displayed at a time half way between the display times of the first and second frames.
    Type: Grant
    Filed: October 7, 1998
    Date of Patent: September 16, 2003
    Assignee: National Semiconductor Corporation
    Inventor: Chang Y. Choo
  • Patent number: 5991455
    Abstract: A hashing-based vector quantization process partitions a codebook into buckets. A hashing function determines the locations of buckets in the codebook and is selected so that buckets containing similar codevectors start near each other in the codebook. One hashing function forms an index from the most significant bits of components of a vector. During encoding, the hashing function generates an index from an input vector, and a search for a codevector matching the image vector begins in a bucket indicated by the index. In one embodiment, the codebook contains flag fields to indicate the starts of buckets and pointer fields to create linked lists of codevectors which form the buckets. Codevectors are compared to the input vector by determining the mean squared error of the difference between the codevector and the input vector. A search is complete when the search finds a codevector having a difference with a MSE less than a threshold.
    Type: Grant
    Filed: February 3, 1998
    Date of Patent: November 23, 1999
    Assignee: National Semiconductor Corporation
    Inventors: Chang Y. Choo, Xiaonong Ran
  • Patent number: 5943096
    Abstract: A video decoding and display system uses temporal post-processing to smooth motion in a displayed moving image. The temporal post-processing uses motion vectors each of which indicates visually similar areas in first and second frames to generate interpolated motion vectors which match areas in an interpolated frame to visually similar areas in the first and second frames. In one embodiment, each component of each motion vector is divided by two and used to generate an interpolated frame half way between the first and second frames. Display of the first and second frames are delayed so that the interpolated frame is displayed at a time half way between the display times of the first and second frames.
    Type: Grant
    Filed: March 24, 1995
    Date of Patent: August 24, 1999
    Assignee: National Semiconductor Corporation
    Inventor: Chang Y. Choo
  • Patent number: 5832131
    Abstract: A hashing-based vector quantization process partitions a codebook into buckets. A hashing function determines the locations of buckets in the codebook and is selected so that buckets containing similar codevectors start near each other in the codebook. One hashing function forms an index from the most significant bits of components of a vector. During encoding, the hashing function generates an index from an input vector, and a search for a codevector matching the image vector begins in a bucket indicated by the index. In one embodiment, the codebook contains flag fields to indicate the starts of buckets and pointer fields to create linked lists of codevectors which form the buckets. Codevectors are compared to the input vector by determining the mean squared error of the difference between the codevector and the input vector. A search is complete when the search finds a codevector having a difference with a MSE less than a threshold.
    Type: Grant
    Filed: May 3, 1995
    Date of Patent: November 3, 1998
    Assignee: National Semiconductor Corporation
    Inventors: Chang Y. Choo, Xiaonong Ran
  • Patent number: 5587710
    Abstract: A coder/decoder selects one of a set of look-up tables for encoding/decoding a symbol. Each look-up table contains boundary values that result from an arithmetic coding model partitioning a first interval. A second interval contains an arithmetic code. During encoding, look-up table entries for a symbol value are converted to the scale of the second interval. The scaled values indicate a smaller interval containing the arithmetic code. Code bits are generated when most significant bits of upper and lower scaled values are equal. During decoding, a code word, which is a part of an arithmetic code, is normalized from the scale of the second interval to the scale for a look-up table and then compared to entries of the look-up table. When a segment containing the code word is identified, a decoded symbol value is known. A scaling circuit converts boundary values for the segment to the scale of the second interval then changes the second interval.
    Type: Grant
    Filed: March 24, 1995
    Date of Patent: December 24, 1996
    Assignee: National Semiconductor Corporation
    Inventors: Chang Y. Choo, Xiaonong Ran, Christine A. Porter, Mohammad R. Motamedi