• Applied Science and Convergence Technology
• /
• v.24 no.5
• /
• pp.178-183
• /
• 2015

Optical, electrical and structural properties of VOx/ZnO/VOx thin film are studied. The VOx/ZnO/VOx multilayer is deposited by using a radio frequency (RF) sputtering system. The VOx/ZnO/VOx thin film shows the high temperature coefficient of resistance (TCR) of $-3.12%/^{\circ}C$ and the low sheet resistance of about 80 $k{\Omega}/sq$ at room temperature. The responsivity and detectivity of the bolometer are measured as a function of modulation frequency.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.4 no.3
• /
• pp.149-167
• /
• 2004

Passive components are indispensable in the design and development of microchips for high-frequency applications. Inductors in particular are used frequently in radio frequency (RF) IC's such as low-noise amplifiers and oscillators. This paper gives a broad overview on the on-chip spiral inductors. The design concept and modeling approach of the typical square-shaped spiral inductor are first addressed. This is followed by the discussions of advanced structures for the enhancement of inductor performance. Research works reported in the literature are summarized to aid the understanding of the recent development of such devices.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.9 s.112
• /
• pp.852-859
• /
• 2006

This paper suggests a developing approach of EHF TWTA for satellite communications. In order to improve RF performance and gain, we design and realize an EHF TWTA using a linearizer and drive amplifiers. Through the embodiment and experiment of 80 W EHF TWTA, this method satisfies the design specifications. Therefore, this approach is very useful and can be used to develop the similar equipments.

• Journal of Veterinary Clinics
• /
• v.16 no.1
• /
• pp.75-79
• /
• 1999

Magnetic resonance imaging (MRI) is an imaging technique used to produce high quality images of the inside of the animal body. MRI is based on the principles of nuclear magnetic resonance (NMR) and started out as a tomographic imaging technique, that is it produced an image of the NMR signal in a thin slice through the animal body. The animal body is primarily fat and water, Fat and water have many hydrogen atoms. Hydrogen nuclei have an NMR signal. For these reasons magnetic resonance imaging primarily images the NMR signal from the hydrogen nuclei. Hydrogen protons, within the body align with the magnetic field. By applying short radio frequency (RF) pulses to a specific anatomical slice, the protons in the slice absorb energy at this resonant frequency causing them to spin perpendicular to the magnetic field. As the protons relax back into alignment with the magnetic field, a signal is received by an RF coil that acts as an antennae. This signal is processed by a computer to produce diagnostic images of the anatomical area of interest.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.4
• /
• pp.632-638
• /
• 2012

ZigBee network, based on PHY, MAC layer provides a specification for a suite of high level communication protocols using small, low-power digital radio based on an IEEE 802.15.4 standard. Meshing is a type of daisy chaining from one device to another. This technique allows the short range of an individual node to be expanded and multiplied, covering a much larger area. Each wireless technology that makes it to market serves a special purpose or function. Zigbee provides short-range connectivity in what is called a personal-area network (PAN). Within ZigBee PAN coordinator as manages an entire ZigBee network, the short range of frequency band was only selected because the technology allows typically less than 100 kbp or ZigBee troubles in retransmission processing and delaying data tranmission works to create unproductive condition of work. This research was proposed the method, based on short range frequency of zigBee nodes enable to long range of remote data transmission with specific algorithm tools.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2007.05a
• /
• pp.468-472
• /
• 2007

For small capacity rectifier circuits such as these for consumer electronics and appliances, capacitor input type rectifier circuits are generally used. Consequently, various harmonics generated within the power system become a serious problem. Various studies of this effect have been presented previously. The absence of switching devices makes systems more tolerant to over-load, and brings low radio noise benefits. We propose a power factor correction scheme using a LC resonant in commercial frequency without switching devices. In this method, It makes a sinusoidal wave by widening conduction period using the current resonance in commercial frequency, Hence, the harmonic characteristics can be significantly improved, where the lower order harmonics, such as the fifth and seventh orders are much reduced. The result are confirmed by the theoretical and expermental implementations

• Electronics and Telecommunications Trends
• /
• v.20 no.3 s.93
• /
• pp.67-80
• /
• 2005

RFID 기술은 각 사물에 전자태그를 부착하고, 사물의 고유 ID를 무선으로 인식하여,해당 정보를 수집, 저장, 가공, 추적함으로써 사물에 대한 측위, 원격 처리, 관리 및 사물간 정보교환 등의 서비스를 제공하는 기술이다. RFID 기술은 칩, 태그, 리더, 미들웨어 및 응용 서비스 플랫폼으로 구성되고 유무선 통신망과 연동되어서 사용된다. RFID기술은 사람 중심(anyone)에서 사물 중심(anything)으로 정보화의 지평을 확대시킬수 있는 핵심 기술로 부각되고 있으며, 유비쿼터스 센서 네트워크로 발전될 전망이다. 본 고에서는 900MHz 대역을 이용하는 수동형 RFID 시스템과 433MHz 대역을 이용하는 능동형 RFID 시스템의 주요 구성 요소와 관련 기술 동향 및 전망을 알아본다.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2002.11a
• /
• pp.16-20
• /
• 2002

This paper describes the resistive FET mixer with low IF for the 4-Ch DBF(Digital Beam Forming) receiver with LNA(Low Noise Amplifier). This DBF receiver based on the direct conversion method is generally suitable for high-speed wireless mobile communications. A radio frequency(RF), a local oscillator(LO) and an intermediate frequency(IF) considered in this research are 2.09 ㎓, 2.08 ㎓ and 10㎒, respectively. The RF input power, LO input power and Vgs are used -10㏈m, 6㏈m and -0.4 V, respectively. In the 4-Ch resistive FET mixer with LNA, the measured IF and harmonic components of 10㎒, 20㎒, 2.09㎓ and 4.17㎓ are about -12.5 ㏈m, -57㏈m, -40㏈m and -54㏈m, respectively. The IF output power observed at each channel of 10㎒ is about -12.5㏈m and it is higher 27.5 ㏈m than the maximum harmonic component of 2.09㎓. Each IF output spectrum of the 4-Ch is observed almost same value and it shows a good agreement with the prediction.

• Journal of Magnetics
• /
• v.20 no.4
• /
• pp.460-465
• /
• 2015

The paper presents methodologies and results concerning one- and two-dimensional numerical modeling of radio frequency oscillations in a coaxial transmission line fed with a short pulse of electric current. The line is partially filled with a ferrite material, magnetized longitudinally close to saturation. The 2D model has permitted analyzing, for the first time in the art, the spatial structure and dynamics of the wave field within the radially non-uniform cross-section planes of the non-linear and dispersive guiding structure. This opens ways for optimizing size parameters of the line and the extent to which it is filled with the ferromagnetic material, thus increasing the line's electric strength and intensity of the r.f. oscillations.

• Proceedings of the KIEE Conference
• /
• 2002.11c
• /
• pp.418-421
• /
• 2002

The immunity testing in this study was performed to examine the conducted immunity and radiated immunity in medical instrumentation. Experiments were performed to assess the conducted emission and radiated emission of medical instrumentation such as MRI, ultrasound system, and electro surgical unit etc. The emission testing revolves around conducted emissions (high-frequency currents) on power lines and signal cables. Emission testing also looks at the output of energy through the air (called radiated emissions) and analyzes the strength of those radio-frequency signals generated unintentionally by the electrical medical device that is under test. Finally, this study would provide significant data for furture research or electromagnetic interference and compatibility test in medical instrumentation.