• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2318-2320
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• 2005

In this paper, a low noise amplifier(LNA) in a receiver of a Low Noise Block Down Converter (LNB) for direct broadcasting service(DBS) is implemented using GaAs HEMT. The LNA is designed for the bandwidth of 11.7GHz-12.2GHz. The 2stage-LNA consists of a input matching circuit, a output matching circuit, DC-blocks and RF-chokes. The result of a simulation of the LNA using Advanced Design System(ADS) shows the noise figure less than 1.4dB, the gain greater than 23dB and the flatness of 1dB in the bandwidth of 11.7 to 12.2GHz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7957-7963
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• 2015

R&D trend for Auxiliary Power Supply(APU) of electric vehicle can be well understood by analyzing patents at home and abroad. Based on this trend analysis, domestic technology development direction is proposed. To get technique trend, patents of Korea, Japan, Europe and America published until February of 2014 are analyzed by WIPS DB. First, power converter and transformer two big category are classified. Power converter can be classified into resonant DC to DC converter and resonant Half bridge inverter; transformer can be classified into high frequency transformer, ferrite transformer and matching transformer. By analyzing R&D trend of different counties, companies and years, specific technology needed to be developed and trend of technology can be accurately grasped.

• Journal of electromagnetic engineering and science
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• v.13 no.2
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• pp.137-139
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• 2013

A compact metamaterial (MTM)-based tunable phase shifter consisting of four unit cells with a simple DC bias circuit has been designed at 2.4 GHz. The variable series capacitors and shunt inductors that are required to be loaded periodically onto a host transmission line are realized employing only chip variable capacitors (varactors). In addition, the proposed phase shifter requires only one DC bias source to control the varactors, with the matching condition of the MTM line automatically satisfied. The measured phase shifting range is $285.2^{\circ}$ (from $-74.2^{\circ}$ to $211^{\circ}$). The measured insertion loss is approximately 1.5 dB. The circuit/electromagnetic-simulated and measured results are in good agreement.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.288-292
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• 2002

We propose the new type of on-chip ESD protection method for RF applications. By using the properties of RF circuits, we can use the short-circuited stub as ESD protection device in front of the DC blocking capacitor Specially, we can use short-circuited stub as the portion of the matching circuit so to reduce the and various parameters of the transmission line. This new type ESD protection method is very different from the conventional ESD protection method. With the new type ESD protection method, we remove the parasitic capacitance of ESD protection device which degrade the performance of core circuit.

• Korean Journal of Optics and Photonics
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• v.4 no.1
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• pp.84-89
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• 1993

Spatial homogenity of Mg (4 mole %):LiNb$O_3$ is investigated by studying the characteristic of Second Harmonic Generation in Mg:LiNb$O_3$ as a function of temperature and DC Electric Field. It is found that the temperaturs at which the intensity of the second harmonic is reduced to the first zero from its maximum for the phase matching condition is shifted linearly to the strength of DC Electric field applied to optic axis of Mg:LiNb$O_3$. From these results, the electro-optic coefficient of Mg:LiNb$O_3$ is estimated to be higher than that of Congruent LiNb$O_3$ by a factor of 1.5.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.3
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• pp.88-95
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• 1994

A scheme of IESFVSC(Integral Error State Feedback Variable Structure Controller) is proposed for a DC servo position control system with the disturbances which do not satisfy the matching condition. The proposed control system is composed of servo compensator and state feedback VSC. The servo compensator enhances the robustness of the control system against various types of disturbance, and makes effective tracking possible without using error dynamics. The IESFVSC is applied to the practical design of a robust DC servo control system and the control performances are verified through theoretical analyses and simulations.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.9
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• pp.1344-1350
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• 1990

A design method of ultra-broadband microwave amplifier is presented. A lossy network is represented as the combination of a serial impedance component and a parallel admittance component, and the realizable ranges of the gain and the reflection coefficients are derived with the components connected to the input, output or interstage network. The matching network has been designed by using the serial and parallel immittance loci which have the constant gain or reflection coefficients within the realizable ranges. Using the proposed method, deisgn examples of ultra-broadband amplifiers operating from dc to 12GHz frequency range are presented.

• Korean Journal of Food Science and Technology
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• v.21 no.4
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• pp.562-568
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• 1989

The essential oils from ripe fruit peel and leaf of Zanthoxylum piperitum DC were extracted by gas co-distillation method and analyzed by gas chromatography/mass spectrometry (GC/ MS) and retention index matching. The experimental results revealed the presence of over 100 volatile components. Major components were 1,8-cineol (25.47%), limonene (11.91%), geranyl acetate (9.01%), myrcene (6.15%) in fruit peel and citronellal (23.11%), 1,8-cineol (18.38%), citronellol (6.04%) in leaf. Among the components identified were the following; in fruit peel, ${\alpha}-pinene$ and 13 hydrocarbons, linalool and 8 alcohols, citronellal and 3 aldehydes, carvone and 2 kotones, methyl salicylate and 7 esters, and 1,8-cineol and oxides, and in leaf, ${\alpha}-pinene$ and 7 hydrocarbons, linalool and 7 alcohols, citronellyl acetate and 5 esters, citronellal and 1 aldehyde, carvone, and 1,8-cineol and 1 oxide.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.4
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• pp.362-370
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• 2010

In this paper, a compact RF Front-end module for Wireless Fidelity(Wi-Fi) and Worldwide Interoperability for Microwave Access(WiMAX) applications is realized by low temperature co-fired ceramic(LTCC) technology. The RF Front-end module is composed of three LTCC band-pass filters, a Film Bulk Acoustic Resonator(FBAR) filter, fully embedded matching circuits, an SPDT switch for mode selection, an SPDT switch for Tx/Rx selection, and an SP4T switch for band selection. The parasitic elements of 0.2~0.3 pF are generated by the structure of stacking in the top pad pattern for DC block capacitor of SPDT switch for mode selection. These kinds of parasitic elements break the matching characteristic, and thus, the overall electrical performance of the module is degraded. In order to compensate it, we insert a parallel lumped-element inductor on capacitor pad pattern for DC block, so that we obtain the optimized performance of the RF Front-end module. The fabricated RF front-end module has 12 layers including three inner grounds and it occupies less than $6.0mm{\times}6.0mm{\times}0.728mm$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.10 s.113
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• pp.929-934
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• 2006

In the paper, we suggest a simpler synthesis technique for capacitively-coupled match circuit(CCMC) which have a function of DC block and impedance matching simultaneously, and introduce a stability margin analysis technique for designing microwave amplifier under conditionally stable state. Stability margin analysis is used to determine optimum match point that ensure maximum gain under the given stability margin. It can reduce time consuming work for selecting match points in the conditionally stable state. Also, suggested miniaturization scheme of matching network is distinguished from previous work with respect to reducing deterministic parameters for CCMC synthesis. To verify utility of suggested method, 24 GHz gain block is fabricated under conditionally stable state using an internal thin-film fabrication process, Measured results show a stable gain of 10 dB and flatness of 1 dB, which is well coincident with simulated one.