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[Author] Won HA(6hit)

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  • A Low Noise CMOS Low Dropout Regulator with an Area-Efficient Bandgap Reference

    Sangwon HAN  Jongsik KIM  Kwang-Ho WON  Hyunchol SHIN  

     
    LETTER-Electronic Circuits

      Vol:
    E92-C No:5
      Page(s):
    740-742

    In a low dropout (LDO) linear regulator whose reference voltage is supplied by a bandgap reference, double stacked diodes increase the effective junction area ratio in the bandgap reference, which significantly lowers the output spectral noise of the LDO. A low noise LDO with the area-efficient bandgap reference is implemented in 0.18 µm CMOS. An effective diode area ratio of 105 is obtained while the actual silicon area is saved by a factor of 4.77. As a result, a remarkably low output noise of 186 nV/sqrt(Hz) is achieved at 1 kHz. Moreover, the dropout voltage, line regulation, and load regulation of the LDO are measured to be 0.3 V, 0.04%/V, and 0.46%, respectively.

  • Real-Time Re-transmission from ATSC to OpenCable

    Byungjun BAE  Joungil YUN  Young-Kwon HAHM  Soo-In LEE  Byung-Ha AHN  Kyu-Ik SOHNG  

     
    LETTER

      Vol:
    E87-A No:6
      Page(s):
    1524-1526

    To meet the needs of various consumers and reuse of digital broadcasting programs, it is necessary to re-transmit the digital broadcasting program produced by a variety of digital broadcasting standards over the different digital broadcasting systems. Especially, some channels in digital terrestrial broadcasting must be re-transmitted through the digital cable broadcasting in Korean digital broadcasting environment. In this paper, we present two possible methods for re-transmission from the digital terrestrial broadcasting to digital cable broadcasting, and propose a real-time re-transmission system.

  • Interference Suppression Based on Code Grouping and Groupwise Decorrelation in Multirate W-CDMA Downlink

    Won HA  Junghwa BAE  Jinwoo PARK  

     
    LETTER-Wireless Communication Technologies

      Vol:
    E87-B No:10
      Page(s):
    3125-3129

    In this paper, we presented a new interference suppression method based on groupwise decorrelation for the multirate wideband-code division multiple access (W-CDMA) downlink. Code grouping in the proposed method is performed according to the correlation property between the mother code and the child code in the orthogonal variable spreading factor (OVSF) code tree. The decorrelation process based on the grouped codes, so called groupwise decorrelation, is then performed to suppress the interference induced in the downlink propagation. We demonstrate that the proposed method can enhance the performance significantly, with lower computational complexity and higher operational efficiency in which any information about interference users (code, data, amplitude) is not required to know in prior at the detection stage.

  • Image Resizing in an Arbitrary Transform Domain

    Won Ha Kim   Hyung Suk OH  

     
    LETTER-Multimedia Systems for Communications

      Vol:
    E92-B No:1
      Page(s):
    346-349

    This paper develops a methodology for resizing image resolutions in an arbitrary orthogonal block transform domain. To accomplish this, we represent the procedures resizing images in an orthogonal transform domain in the form of matrix multiplications from which the matrix scaling the image resolutions is produce. The experiments showed that the proposed method produces reliable performance without increasing the computational complexity, compared to conventional methods when applied to various transforms.

  • Performance Enhancements in MIL-STD-188-220-Based Tactical Communication Systems

    Sewon HAN  Byung-Seo KIM  

     
    LETTER-Mobile Information Network and Personal Communications

      Vol:
    E97-A No:2
      Page(s):
    713-716

    MIL-STD-188-220 standard specifies protocols for narrowband and voice-based tactical communication devices. However, the future tactical communication devices require broadband services for accurate command and control. In this letter, the enhancement for MIL-STD-188-220-based systems is proposed for use over wideband channels. Unlike the operation defined in the standard, transmissions in Bump-Slots uses P-Persistence method and give the higher p to stations experiencing longer delays. The proposed method is extensively evaluated and the performance enhancements are proved.

  • Efficient Voice Transmissions for MIL-STD-188-220-Based Wideband Tactical Systems

    Sewon HAN  Byung-Seo KIM  

     
    LETTER-Network

      Vol:
    E95-B No:9
      Page(s):
    2964-2967

    Unlike analogue voice signal-oriented and narrowband-based conventional tactical systems, the future tactical networks will deal with packet-based voice traffic over a wide channel bandwidth. In this paper, a method is proposed to improve the performance of voice packet transmission for MIL-STD-188-220 military standard-based wideband communication systems. By utilizing Bump-Slots for voice packet transmissions, significant improvements are achieved. This is confirmed by extensive simulations.