• Advanced Composite Materials
• /
• 제17권3호
• /
• pp.215-224
• /
• 2008

The present study aims to design a multilayer microstrip antenna with composite sandwich construction and investigate fatigue behavior of this multilayer SAS (surface antenna structure) that was asymmetric sandwich structure for the next generation of structural surface technology. This term, SAS, indicates that the structural surface becomes an antenna. Constituent materials were selected considering electrical properties, dielectric constant and tangent loss as well as mechanical properties. For the antenna performance, antenna elements inserted into structural layers were designed for satellite communication at a resonant frequency of 12.2 GHz. From electrical measurements, it was shown that antenna performances were in good agreement with design requirements. In cyclic 4-point bending, flexure behavior was investigated by static and fatigue test. Fatigue life curve of the SAS was obtained. The experimental results of bending fatigue were compared with single load level fatigue life prediction equations and in good agreement. The SAS concept is can be extended to give a useful guide for manufacturers of structural body panels as well as antenna designers.

• 전기학회논문지P
• /
• 제57권1호
• /
• pp.56-59
• /
• 2008

We have designed 4 types(void in insulation paper, protrusion electrode, floating electrode, surface discharge) of partial discharge(PD) defect to simulate typical faults found in oil filled power transformers. Ultra-high frequency(UHF) radiation due to PD was measured using a UHF measuring system and a conventional PD measuring system, simultaneously. Electromagnetic radiation spectra of these defects show UHF radiation up to about 1.5-2 GHz range. The phase resolved partial discharge(PRPD) patterns of UHF radiation from the PD defects were also measured and the pattern reveals distinct feature for each defect types. The UHF measuring could be used to detect PDs in oil filled transformers and analysis of the PRPD pattern should provide useful information on origin of PD signal.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2005년도 전력전자학술대회 논문집
• /
• pp.479-482
• /
• 2005

본 연구는 알루미늄 단조 라인의 가열로 컨베이어에 적용된 6관절 이송용 로봇에 Machine Vision System을 구축 한 것으로 이송용 로봇이 작업 대상물을 적재하기 위한 위치정보를 획득하고 재처리하여 로봇 컨트롤러에 제공하는 비주얼가이던스 기법을 연구하여 이를 적용하였다. 적용된 Machine Vision System이 실제 구동에 있어서 안정함을 확인하였다. Machine Vision System에 적용된 CCD 센서로는 Sony사의 XC-HR50이 적용되었으며 Frame Grabber는 Matrox Meter II 카드가 적용되었다. Machine Vision System 제어기로는 범용PC(2.4Ghz, Windows 2000)를 사용하였으며 제어Software는 Microsoft 사의 Visual Basic 6.0 version을 사용하였다.

• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2002년도 추계학술발표논문집 (중)
• /
• pp.1371-1374
• /
• 2002

본 논문에서는 내장형 리눅스를 기반으로 무선 네트웍과 실시간 음성처리 VoIP 와의 연동시스템을 설계 구현한다. 설계 구현하는 시스템의 하드웨어 스펙은 Motorola-XPC860 프로세서를 기반으로 설계되었으며, 음성 코덱칩을 사용하여 실시간으로 음성데이터를 처리하도록 설계하였다. 또한 2.4GHz 무선 통신 규약인 Bluetooth 를 무선 네트웍 인터페이스로 사용하였다. 실시간 음성데이터의 효과적인 처리를 위하여 실시간 운영 체제인 RTLinux 를 사용하였으며, 무선 네트워크의 동시다중 서비스 지원을 위해 커널레벨의 문자 디바이스 형태로의 Bluetooth 인터페이스 구현에 대해 살펴보도록 하겠다.

• Journal of Electrical Engineering and information Science
• /
• 제2권6호
• /
• pp.171-176
• /
• 1997

A hair-pin shaped microstrip-line resonator and dielectric resonator for injection-locked oscillators have been designed and fabricated for the comparative studying of their performances. In general, a commonly used dielectric resonator shows lower phase noise value than hair-pin resonator in the free-running mode. In the injection-locked mode, however, a hair-pin resonator is superior to the dielectric resonator, the wider tuning range, the 22% improved locking bandwidth, the lower noise effect, the short term stability, and the higher power level. The planar structure of a hair-pin shaped microstrip-line resonator will be easily applied to monolithic microwave integrated circuits.

• Transactions on Electrical and Electronic Materials
• /
• 제7권3호
• /
• pp.103-107
• /
• 2006

In this paper, a CMOS complementary bridge rectifier for driving RFID transponder chips is presented. The proposed RFID CMOS complementary bridge rectifier is designed with two NMOSs at the input, which are configured by cross-connected gate structures, and two PMOSs and two NMOSs at the output, which are configured by diode-connected MOS structures. Output characteristics of the proposed rectifier are analyzed with the high frequency small-signal equivalent circuit and verified with SPICE for RFID operating frequencies of 13.56 MHz HF for ISO 18000-3, 915MHz UHF for ISO 18000-6, and 2.45 GHz microwave for ISO 18000-4. Simulation results show well-rectified and high enough DC output voltages for driving the low power microchip in the RFID transponder for the frequency range from HF to microwave. DC output voltages are dropped by only around 0.7 V from the input peak-to-peak voltages.

• ETRI Journal
• /
• 제30권4호
• /
• pp.615-617
• /
• 2008

A novel and compact elliptic-function bandpass filter is proposed in this letter. The techniques of slot etching and the addition of open stubs are applied to enhance the self-inductance and self-capacitance of hexagonal open-loop resonators. Thus, size reduction and improved transmission performance are obtained. Compared to the performance of the conventional design, the central frequency and insertion loss are reduced by 28% and 3.1 dB, respectively. Measurements show that the proposed filter has a fraction bandwidth of 23% at the central frequency of 1.84 GHz, and its insertion loss in the passband is less than -1.5 dB. The bandpass filter occupies only 12 mm${\times}$21.2 mm (approximately $0.24{\lambda}_g{\times}0.14{\lambda}_g$).

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
• /
• pp.131-134
• /
• 2004

The object of this study is to design the Radar Absorbing Structures (RAS) having sandwich structures in the X-band $(8.2\~12.4GHz)$ frequencies. Glass fabric/epoxy composites containing conductive carbon blacks and carbon fabric/epoxy composites were used for the face sheets. Polyurethane (PU) foams containing multi­walled carbon nanotube (MWNT) were used for the core. Their permittivities in the X-band were measured using the transmission line technique. The reflection loss characteristics for multi-layered sandwich structures were calculated using the theory of transmission and reflection in a multi-layered medium. Three kinds of specimens were fabricated and their reflection losses in the X-band were measured using the free space technique. Experimental results were in good agreements with simulated ones in 10dB absorbing bandwidth.

• ETRI Journal
• /
• 제26권1호
• /
• pp.57-60
• /
• 2004

We propose an inductive compensation method for a surface-mountable 10 Gbps photoreceiver module. Since many typical 10 Gbps photoreceiver modules consist of a photodetector and low-noise pre-amplifier, the impedance mismatch between the photodetector and pre-amplifier, as well as package parasitics, may reduce the frequency bandwidth. In this paper, we inserted an inductive component between the photodetector and pre-amplifier in order to create frequency bandwidth expansion. From the measurement results, we have found that the proposed technique can increase the -3 dB bandwidth about 4.2 GHz wider compared with an uncompensated module. And, from a bit-error rate (BER) test, we observed -15.7 dB sensitivity at $10^{-12}$ BER. This inductive compensation can be implemented easily and is compatible with common manufacturing processes of photoreceiver modules.

• 전자통신동향분석
• /
• 제16권6호통권72호
• /
• pp.117-125
• /
• 2001

본 고에서는 최근 무선데이터 통신시스템용으로 2.4GHz 대역에서 블루투스 등 새로운 통신기기가 출현함에 따라서 이러한 기기에서 사용되는 여러 확산방식 중 직접열확산방식을 중심으로 하여 국내의 기술기준에 근거한 일본, 미국, 유럽의 측정방법에 대하여 검토하였다. 이러한 검토를 통하여 다양한 측정 방법들이 갖는 특징과 차이점들을 분석하여 국내에 적용할 수 있는지를 검토하고자 한다. 그리고 점유주파수대역폭, 주파수 허용편차, 공중선전력, 불요발사 등의 세부적인 항목을 함께 다루며, 각각의 측정 항목에 관한 구체적인 방법과 절차를 살펴볼 것이다.