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[Author] Jun PARK(3hit)

1-3hit
  • Chaotic Order Preserving Encryption for Efficient and Secure Queries on Databases

    Seungmin LEE  Tae-Jun PARK  Donghyeok LEE  Taekyong NAM  Sehun KIM  

     
    PAPER-Database

      Vol:
    E92-D No:11
      Page(s):
    2207-2217

    The need for data encryption that protects sensitive data in a database has increased rapidly. However, encrypted data can no longer be efficiently queried because nearly all of the data should be decrypted. Several order-preserving encryption schemes that enable indexes to be built over encrypted data have been suggested to solve this problem. They allow any comparison operation to be directly applied to encrypted data. However, one of the main disadvantages of these schemes is that they expose sensitive data to inference attacks with order information, especially when the data are used together with unencrypted columns in the database. In this study, a new order-preserving encryption scheme that provides secure queries by hiding the order is introduced. Moreover, it provides efficient queries because any user who has the encryption key knows the order. The proposed scheme is designed to be efficient and secure in such an environment. Thus, it is possible to encrypt only sensitive data while leaving other data unencrypted. The encryption is not only robust against order exposure, but also shows high performance for any query over encrypted data. In addition, the proposed scheme provides strong updates without assumptions of the distribution of plaintext. This allows it to be integrated easily with the existing database system.

  • Motion Evaluation for Rehabilitation Training of the Disabled

    Tae-young KIM  Jun PARK  Cheol-Su LIM  

     
    LETTER-Vision

      Vol:
    E91-A No:9
      Page(s):
    2688-2690

    In this paper, a motion evaluation technique for rehabilitation training is introduced. Motion recognition technologies have been developed for determining matching motions in the training set. However, we need to measure how well and how much of the motion has been followed for training motion evaluation. We employed a Finite State Machine as a framework of motion evaluation. For similarity analysis, we used weighted angular value differences although any template matching algorithm may be used. For robustness under illumination changes, IR LED's and cameras with IR-pass filter were used. Developed technique was successfully used for rehabilitation training of the disabled. Therapists appraised the system as practically useful.

  • Effective Recovery Algorithm from Multiple Packet Losses in the Start-Up Behavior for TCP over ATM-UBR Service

    Woochool PARK  Sangjun PARK  Byungho RHEE  

     
    PAPER

      Vol:
    E84-A No:6
      Page(s):
    1378-1382

    This paper proposes two modes of the congestion control scheme to improve its behavior during the start-up period of networks in current TCP over ATM-UBR implementation. The proposed two modes are a single packet loss mode and a multiple packet losses mode. The proposed algorithm is to minimize the number of cell losses in the ATM switch during specially the start-up period. During the start-up period, multiple packet losses often happens because a TCP sender starts with default parameters. It often ends up sending too many packets and too fast, leading to multiple losses is packet burstiness which occurs right after fast recovery ends. We analyze the transition behavior during fast recovery algorithm and estimate the number of new packets sent when multiple packet losses detected. We present a simple simulation model and numerical results to investigate its performance of the proposed algorithms.