• Journal of electromagnetic engineering and science
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• v.6 no.4
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• pp.217-221
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• 2006

Multipactor-free S-band duplexer based on inter-digital cavity type filter is proposed and demonstrated by in-house mulitpactor test facility for satellite RF components. Multipactor sensitivity of designed duplexer is analyzed by checking it out the maximum field accumulated region inside duplexer and calculating the electric field intensities at each resonator using 3D EM simulation in order to restrict the minimum gap distance as 2.5 mm which handles 43.13 dBm RF input power. Multipactor threshold was finally detected at 44 dBm in experiment for pulse mode test. The developed multipactor test method is cost effective, simple structure and gives a good agreement compared with the previous high cost MP test methodologies.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1319-1322
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• 2015

일반적으로 이차전지를 이용한 에너지 저장 시스템(ESS, Energy Storage System)과 전기 자동차(EV, Electric Vehicle)에 사용되는 전지(Battery)는 용량에 따라 직 병렬로 수십 개에서 수 만개의 배터리가 사용되기도 한다. 이러한 많은 배터리를 제어하고 관리하기 위해 필요한 것이 배터리 관리 시스템(BMS, Battery Management System)이다. 이러한 BMS는 ESS(Energy Storage System, 에너지저장시스템)의 핵심부품으로서, 관련업계에서는 새로운 기술 개발에 박차를 가하고 있다. 따라서 본 논문에서는 최근 개발되고 있는 AC 임피던스를 이용한 SOH 예측 기능을 검증할 수 있는 DSP(Digital Signal Processing) Platform 기반으로 Master-Slave 형태의 BMS를 개발하였으며, Master-Slave간에는 CAN 통신을 이용하여 제어성, 확장성을 용이하게 함으로써, 새로운 SOH 알고리즘 구현 및 성능 검증을 손 쉽게 구현할 수 있게 되었다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.07a
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• pp.388-389
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• 2017

본 논문에서는 효율적인 에너지 관리를 위해 리튬이온 배터리를 적용 능동 셀 밸런싱 시스템 BMS에 대해 제안하였다. 제안된 방법은 다수의 셀과 하나의 커패시터로 구성된 SSC(Single Switched Capacitor) 방식에서 사용되는 커패시터를 리튬이온 배터리로 변경하여 적용한 것이다. SSC 방식은 커패시터의 방향성으로 인하여 홀수 번째와 짝수 번째의 배터리에 대해 별도의 스위치를 설치하여야 하며 조작이 복잡하다는 단점을 가지고 있었다. 이러한 단점을 보완하여 커패시터를 리튬이온 배터리로 대체하여 셀의 순서에 상관없이 적용이 가능한 셀 밸런싱 방법을 제안하였다. 제안된 방법의 효율성은 BMS를 구현하여 실험 하였다. 실험 결과 셀 밸런싱이 기존의 SSC 방식보다 개선되어 효율성이 입증되었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.6
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• pp.540-545
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• 2015

This paper presents the design, fabrication and measurement results of a S-band internally-matched power amplifier using Gallium Nitride High Electron Mobility Transistor(GaN HEMT) die. In order to fabricate the S-band internally-matched power amplifier, a high dielectric substrate and alumina were used for input/output matching circuits. The measured output power is 55.4 dBm, the drain efficiency is 78 % and the power gain is 11 dB under pulse operation at the frequency of 3 GHz.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2006.06a
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• pp.261-262
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• 2006

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.721-724
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• 2001

In this paper, we present the effect the length the MSL(Microstrip Line) on the oscillation characteristic of the fabricated VCOs(Voltage Controlled Oscillator) designed and analyzed by RF circuit simulator Serenade(ANSOFT Co.) and fabricated by screen printing method on the alumina substrate. We have fabricated VCOs with 3 different MSL length and each MSL length of the VCO is 140mi1, 280mil and 560mi1. The oscillation frequency of each sample(VCO) was tuned to UHF band(750MHz∼900MHz) varying the capacitance. The experimental result shows the phase noise -82∼-97[dBc/Hz] at a 50 [kHz] offset frequency, the pushing figure 94∼318[kHz] at 3${\pm}$0.15[V] and the harmonics 13∼21 [dBc] between MSL length 140mi1s and 560mi1. The frequency and output variation width are 779∼898[MHz], -36∼-33[dBm] at MSL length 140mi1; 818∼836[MHz], -27.19∼-27.06[dBm] at 280mi1;751.54∼751.198[MHz],-33.44∼ -33.31[dBm] at 560mi1. we examined 3 VCOs oscillation characteristic difference through comparison with phase noise, oscillation power and frequency by control voltage change, harmonics and pushing figure for each sample.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1572-1579
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• 2009

In this dissertation ultra-broadband power amplifier(UPA) was designed and fabricated using negative feedback technique. UPA was made of pre-amplifier, drive amplifier and power amplifier. Negative feedback technique was used to achieve ultra-broadband performance. Designed power amplifier has 30dB gain and 2W output power. The load-pull data of power amplifier for optimal power matching was extracted from the measured S-parameter. Fabricated PCB material, permittivity is 4.6 and thickness is 0.8mm, is FR4 and UPA was fabricated 3 modules for comparison of the simulated and measured results. Size of the fabricated pre-amplifier and drive amplifier module is 40mm'50mm'16mm. And from the experimental results, gain of the pre-amplifier module is 9.87dB at 2GHz and flatness is 0.63dB. Experimental result of the drive amplifier module is 10.97dB at 2GHz and flatness of that is 0.26dB. Test result of the power amplifier module is 10.71dB at 2GHz and flatness is 0.72dB. Total size of the power amplifier is 45mm'134mm'16mm. According to the test results, gain of the UPA is 28.98dB at 2GHz and flatness is 1.68dB. Output power was 32.098dBm at 2GHz, 32.154dBm at 1GHz and 31.273dBm at 100MHz.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.150-153
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• 2000

In this paper, we have designed a 2 stage MMIC power amplifier which has flat gains of in-band and reasonable out-band cutoff characteristics using 0.5$\mu\textrm{m}$ MESFET libra교 of ETRI. For the 1st stave, we obtaind P$_{1dB}$ of 9.2 dBm and gain 10.8 dB using 6 finger D-MESFET and P$_{1dB}$ of 18.4 dBm and gain of 10.8 dB using 14 finger D-MESFET for the 2nd stage, which is power matched using LIBRA's embedded TUNER. Also in-band gain flatness and out-band cutoff characteristics are obtained by attaching LC tank in the output matching circuit. The designed 2 stage MMIC power amplifier has bandwidth of 0.95～2.8 GHz, gain of 20 dB and P$_{1dB}$of 17.2 dBm. Especially gain flatness of $\pm$0.8dB was obtained in 1.8～2.5 GHz frequency ranges. And chip size is 1.4$\times$1.4 mm..4 mm.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.4
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• pp.559-563
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• 2001

The effects of feeding a mannan oligosaccharide (Bio-Mos) from 0 to 3 g/kg diet and vaccination program on 1- to 35-day performance (growth and feed efficiency), metabolizable energy, nitrogen utilization and carcass composition of meat chickens were investigated. A general vaccination program was used against IB, IBD and ND with half of the birds per diet receiving a booster dose of IB and ND vaccines at 12 days of age. Dietary supplementation of Bio-Mos (BM) did not influence body weight gain, feed efficiency and nutrient utilization. The highest dietary BM (3 versus 1.5 or 0 g/kg) increased carcass abdominal fat and reduced the proportion of drumstick in the carcass of meat chickens. The booster dose reduced the performance of birds. It was concluded that the addition of BM to the diet of chickens did not significantly influence the performance and nutrient utilization of meat chickens.

• International Journal of Industrial Entomology and Biomaterials
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• v.2 no.2
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• pp.149-153
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• 2001

The influence of baculovirus Bombyx mori Nuclear Polyhedrosis virus (BmNPV) infection on intermediary metabolic pathways in silkworm Bombyx mori L. was investigated. Studies revealed that NADP-linked malate dehydrogenase activity in hemolymph of infected silkworms at 96 hrs post infection (p.i.) with visible symptoms of infection was enhanced in comparison to healthy larvae of the same age. Also, NADP-dependent MDH activity was significantly lower in fat body cytosol of infected larvae at 96 hrs p.i. when compared to healthy larvae. Similarly, some biometabolic parameters like growth, protein content and cholesterol titer were observed to be influenced by baculovirus infection. While the growth of infected larvae was significantly retardedi protein content was also drastically reduced in both hemolymph and fat body tissues. Cholesterol titers however, was enhanced in infected larvae. The results observed herein point to a significant change in the normal biochemical and biometabolic pathways required for growth and development following BmNPV infection.