• Journal of Advanced Navigation Technology
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• v.6 no.2
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• pp.158-167
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• 2002

In this paper, it is analyzed that WAP packet transmission time to improve performance of WAP using SAR-QT algorithm in Bluetooth channel. The order for SAR-QT algorithm to improve the transfer capability, it is fragmented in WTP total messages that are coming down from upper layer and then the packets are sent one at time in baseband. And it is studied that transmission time for WAP over Bluetooth according to DMI, DM3 or DM5 packet type using SAR-QT algorithm in Bluetooth piconet environment. This SAR-QT algorithm decreases WAP packet transmission time of L2CAP baseband packets by sending packet that are spanning multiple slots. From the results, in WAP over Bluetooth channels, it is found out that WTP packet size ought to be increased to decrease transmission time of WAP packet. In addition, considering BER in wireless channel, optimal WTP packet size is achieved for WAP over Bluetooth in a Rician fading environment.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.3
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• pp.1-6
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• 2008

A dual band I/Q modulator which converts baseband input signals to 2.4GHz or 5GHz RF output has been proposed. The dual band I/Q modulator for 2.4GHz and 5GHz wireless LAN applications consists of $90^{\circ}$ phase shifter and wideband mixer. The I/Q modulator showed 15dB conversion loss at 2.4GHz and 16dB conversion loss at 5GHz. The sideband suppression is about 15dBc at 2.4GHz and 16dBc at 5GHz. Measured data shows 8.5% EVM at 2.4GHz, and 10% EVM at 5GHz for QPSK with symbol rate of 11Mbps. A carrier rejection is about 40dBc at 2.4GHz/5GHz band, and the I/Q modulator satisfied the output wireless LAN spectrum mask with baseband input signal.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.3
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• pp.35-40
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• 2010

In this paper, we propose a hardware resource sharable camera control processor (CCP) for low-cost and low-power camera cell phones. The main idea behind the proposed architecture is that adds direct access paths in the CCP to share its hardware resources so that the baseband processor expands its capabilities and boosts its performance by utilizing CCF's hardware resources. In addition, we applied a module grain dock-gating method to reduce power dissipation. Hence, the CCP can realize low-power and low-cost camera cell phones with greater hardware efficiency. This chip was fabricated in a 0.18um CMOS process with an active area of $3.8mm\;{\times}\;3.8mm$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10A
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• pp.776-783
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• 2009

Current-cut circuit is an effective method to obtain low power consumption in wireless communication systems as high speed OFDM. For the operation of current-mode FFT LSI with analog signal processing essentially requires current-mode serial-to-parallel/parallel-to-serial converter with multi input and output structure. However, the Hold-mode operation of current-mode serial-to-parallel/parallel-to-serial converter has unnecessary power consumption. We propose a novel current-mode serial-to-parallel/parallel-to-serial converter with current-cut circuit and full chip simulation results agree with experimental data of low power consumption. The proposed current-mode serial-to-parallel/parallel-to-serial converter promise the wide application of the current-mode analog signal processing in the field of low power wireless communication LSI.

• Journal of the Korean Vacuum Society
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• v.20 no.2
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• pp.77-85
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• 2011

The silicon-germanium (SiGe) alloy, which is compatible with silicon semiconductor technology and has a smaller band gap and a lower thermal conductivity than silicon, has been used to fabricate electronic devices such as transistors, photodetectors, solar cells, and thermoelectric devices. This paper reviews the application of SiGe alloys to electronic devices and related technical issues. Since the SiGe alloy comprises germanium whose band gap is smaller than silicon, its band gap is also smaller than that of silicon irrespective of the ratio of silicon to germanium. This narrow band gap of SiGe enables the base thickness of bipolar transistors to decrease without a loss in current gain so that it is possible to improve the speed of bipolar transistors by adopting the SiGe-base. In addition, the conversion efficiency of solar cells is enhanced by the absorption of long-wavelength light in the SiGe absorption layer. Phonon scattering caused by the irregular distribution of alloying elements induces the lower thermal conductivity of SiGe than those of pure silicon and germanium. Because a thin film layer with a low thermal conductivity suppresses thermal conduction through a thermal sink, the SiGe alloy is considered to be a promising material for silicon-based thermoelectric systems.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.590-593
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• 2005

In this paper, it is analyzed a transmission time of ACL Packet in bluetooth wireless link. In order for segment to improve the transfer capability in bluetooth system, it is fragmented in TCP total messages that are coming down from upper layer and then the packets are sent one at time in baseband. And it is studied that transmission time for bluetooth wireless link according to DM1, DM3 or DM5 packet type in bluetooth piconet environment. From the results, we were able to obtain ACL packet transmission time, optimal TCP packet size and DM packet size.

• Journal of Digital Contents Society
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• v.12 no.4
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• pp.575-583
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• 2011

Due to the development of mobile devices and communication technology, cell phones have radically evolved from portable phones into smartphones and provided variety of services to a society. This paper presents Multi-user Musical Instrument application for smart phones based on band instruments such as piano, guitar, bass guitar, and drum. This application makes music playing from smartphone to integrative music data stream using the synchronization function of server. In addition, user can play it of smartphone efficiently by implementing a graphic user interface similar to real musical instruments.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.1182-1187
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• 2006

본 논문은 필립스의 오디오 핑거프린트 추출 방식을 기반으로 기존의 방식이 주파수 영역을 너무 조밀하게 분석하는 특징을 지적하고 개선 방안으로 양자화를 통해 필터 뱅크의 에너지 변화율을 오디오 핑거프린트 추출시 반영하는 방법을 제안하였다. 또한 제안된 알고리즘을 사용하여 PDA 로 실제 어플리케이션을 구현하는 것을 목적으로 하고 있다. 제안된 방식은 필립스 방식과 동일한 메모리 크기를 유지하기 위하여 필터 뱅크의 개수를 33 개에서 17 개로 줄이고 필터 뱅크의 변화량을 2 비트로 할당하는 방식을 사용하였다. 변화량을 비트에 할당하기 위하여 음악 데이터 베이스로부터 추출된 각 밴드의 pmf를 통해 음악의 고유성을 최대로 증진 시킬 수 있는 임계치를 찾아내고 이것을 바탕으로 필터 뱅크의 변화량을 2 비트로 할당하였다. 이 같이 추출된 오디오 핑거프린트를 기반으로 PDA 와 음악 검색기 서버와의 통신을 이용하여 사용자가 요청한 쿼리 음악에 관련된 정보를 제공하는 시스템을 구현했다. 제안된 방식은 다양한 주변 잡음 환경에서 평가되어 기존의 필립스 방식 보다 성능 향상 물론 검색 속도 또한 개선되는 특징을 확인할 수 있었다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.3
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• pp.255-259
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• 2008

In this paper, a current-mode integrator for low-voltage, low-power analog integrated circuits is presented. Using the proposed current-mode integrator, the baseband analog filter is designed for WCDMA wireless communication. To verify the proposed current-mode integrator circuit, Hspice simulation using 1.8V TSMC $0.18{\mu}m$ CMOS parameter is performed and achieved 44.9dB gain, 15.7MHz unity gain frequency. The described 3rd-order current-mode baseband analog filter is composed of the proposed current-mode integrator, and SFG(Signal Flow Graph) method is used to realize the baseband filter. The simulated results show 2.12MHz cutoff frequency which is suitable for WCDMA baseband block.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.643-645
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• 1999

통신망에서 시각/주파수 동기(synchronization)를 맞추기 위해서는 지상망을 이용하거나 위성을 이용하는 방법이 있다. 위성을 이용한 방법에서 지상의 송신국은 정밀시각정보, 위성위치데이타 및 오차보정데이타 등을 위성으로 송신한다. 이를 위해서 송신국의 위성데이터처리장치는 데이터 수집 및 가공, 베이스 밴드부로의 전송시 외부 기능블럭들과 신뢰성 있고 신속한 데이터처리를 수행하여야 한다. 본 논문에서는 한국통신의 무궁화위성을 이용한 시각/주파수 전송시스템 개발의 일환으로 송신국의 위성데이타처리장치에 대한 설계 및 구현 알고리즘을 제시하고자 한다.