• Asian-Australasian Journal of Animal Sciences
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• 제16권1호
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• pp.70-76
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• 2003

Three experiments were conducted to determine the effects of a sorghum-specific enzyme system, derived from an Aspergillus niger and Bacillus subtilis fermentation extract (carbohydrase activity of 1,650 $\alpha$-amylase units and cellulase activity of 30 fibrinolytic units/mL), on growth performance of finishing pigs. In Exp. 1,192 pigs (average initial BW of 46.1 kg) were fed sorghum-based diets without or with 360 mL of enzyme system per ton of sorghum in a 78 d growth assay. For d 0 to 39, gain/feed was improved (p<0.03) with enzyme supplementation, but ADG was not affected (p>0.15). For d 39 to 78 and overall (d 0 to 78), ADG, gain/feed, and digestibilities of DM and N were not affected (p>0.13) by enzyme supplementation. Backfat thickness, fat-free lean index, and scores for stomach keratinization and ulcers also were not affected (p>0.15) by the dietary treatments. In Exp. 2,168 pigs (average initial BW of 58.4 kg) were fed diets without or with 150, 300, or 450 mL/ton of the same enzyme system used in Exp. 1. Adding as much as 450 mL enzyme system / ton of sorghum did not affect (p>0.15) ADG or gain/feed for d 0 to 29 of the growth assay. However, during d 29 to 63, ADG increased by 11% (linear effect, p<0.02) and gain/feed increased by 10% (linear effect, p<0.06) as enzyme concentration was increased from none to 450 mL/ton of sorghum. For the overall period (d 0 to 63), ADG tended to increase (p<0.08) with enzyme supplementation, but gain/feed and digestibilities of DM and N were not affected (p>0.14). Carcass characteristics (dressing percentage, backfat thickness, and fat free lean index) also were not affected (p>0.20) by addition of the enzyme system. In Exp. 3,176 pigs (average initial BW of 46.7 kg) were fed diets without or with 450, 900, or 1,350 mL/ton of the same enzyme system used in Exp. 1 and 2 in a 71 d growth assay. Adding up to 1,350 mL/ton of enzyme had no effects (p>0.15) on ADG, gain/feed, digestibilities of DM and N, and carcass characteristics (dressing percentage, backfat thickness, and fat-free lean index). In conclusion, finishing pigs fed diets with a sorghum-specific enzyme system showed some positive trends for improved growth performance, but those effects were not large and (or) consistent.

• 대한화학회지
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• 제10권3호
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• pp.109-113
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• 1966

By the micro-bioassay method, quantitative studies were made on the increment of body weight and changes in free-lysine and threonine contents in the liver and plasm of rats, when they were fed on sucrose diet added with 0.3% DL-methionine, 0.36% DL-threonine and 0.1% L-tryptophane. The results of the experiment were as follows: (1) The weight gain and growth gain of rats decreased more when they were fed on 0.36% DL-threonine diet (Sth-group) than 0.3% DL-methionine diet (Sm-group). But those gain were increased when they were fed on 0.1% L-tryptophane diet (Str-group). (2) The contents of free-lysine and threonine in plasm and liver of rats were decreased more when they were fed on 0. 36% DL-threonine diet than 0.3% DL-methionine diet. And, those free amino acids were increased greatly when they were fed on 0.1% L-tryptophane diet. (3) The increment of body weight was the biggest when the free amino acid pattern showed that the contents of free-lysine decreased and threonine increased in the plasm and liver of rats being fed on 0.l% L-tryptophane diet.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
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• pp.111-114
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• 2003

In this paper, we consider the stabilization and $H_\infty$ control of linear systems with static output feedback control. The static output feedback control represents the simplest closed-loop control that can be realized in practice, and, moreover, it is less expensive to be implemented and is more reliable. In spite of its advantages, it is one of the open problems which is not sloved analytically or numerically yet. After decompose the closed-loop system into feedback form, by adopting the small gain theorem, we obtain a sufficient condition for stabilization and a sufficient condition for It control expressed as linear matrix inequalites. Finally, we show the usefulness of our results by a numerical example.

• 전자공학회논문지A
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• 제32A권2호
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• pp.48-56
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• 1995

The operating characteristics, such as, the threshold gain, lasing frequency, and longitudinal intensity profile, etc., of 1.55$\mu$m DFB laser diode with index and/or gain grating structures and with one side AR-coated mirror have been analyzed. From this analysis, the optimum design parameters have been shown that ${\Delta}{\Omega}$ (the phase difference between index grating and gain grating) is 0 or ${\pi}$, (xL)$_{r}$=1~3 and (xL)$_{i}$=0.5~0.9. It has been also shown that the modal selectivity and intensity uniformity of the DFB lasers with .DELTA..OMEGA.=0 are ~1.2 times better thatn those of the DFB lasers with ${\Delta}{\Omega}$= ${\pi}$.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.218-220
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• 2004

A new wide-band VCO topology using Miller capacitance is proposed. Contrary to conventional VCO using the Miller capacitance where the variable amplifier gain is negative, the proposed VCO uses both the negative and positive variable amplifier gain to enhance the frequency tuning range significantly. The proposed VCO is simulated using HSPICE. The simulations show that 410MHz and 220MHz frequency tuning range are obtained using the negative .and positive variable amplifier gain, respectively. The tuning range of the proposed VCO is $23\%$ of the center frequency(2.8GHz). The phase noise is -104dBc/Hz at 1MHz offset by simple model. The operating current is only 3.84mA at 2.5V power supply.

• 대한전자공학회논문지TE
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• 제37권2호
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• pp.83-90
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• 2000

본 논문에서는 IMT2000 중계기용으로 1.88-1.98 ㎓ 대역 전력증폭기를 저 가격, 소형으로 개발하였다. 이 전력증폭기는 두 단으로 구성되어 있으며 초단은 P-HEMT (ATF-34143, 800 micron gate width, Agilent Technologies)를 사용하였으며, 종단은 GaAs FET(EFA240D-SOT89, 2400 micron gate width, Excelics Semiconductor)를 사용하였다. 개발된 전력 증폭기는 전체 주파수 대역인 1880-1980 ㎒에서 이득이 29.5㏈, 1㏈ gain compression point는 29.5dBm, 3rd order intercept point(OIP3)는 42dBm 그리고 입출력 return loss는 -10㏈/-l2㏈ 이다. 본 연구에서는 이 전력 증폭기를 설계하기 위하여 각 소자의 비선형 모델을 사용하여 전력증폭기의 여러 가지 비선형 특성을 설계할 수 있었으며, 이 전력 증폭기의 크기는 42(L) x 34(W) mm으로 소형화가 가능하였다.

• 한국정보통신학회논문지
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• 제21권10호
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• pp.1855-1861
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• 2017

본 논문에서는 한 개의 도파기, 두 개의 기생 패치를 이용하여 이중 직렬-급전 다이폴 쌍 안테나(series-fed dipole pair antenna; SDPA)의 이득을 향상시키는 방법에 관하여 연구하였다. 변형된 밸런을 이용하여 대역폭을 늘리고, 한 개의 도파기와 두 개의 기생 패치를 추가하여 중간 및 고주파수 대역에서 이득을 높였다. 도파기와 기생 패치 사이의 거리에 따른 안테나의 특성 변화를 분석하여 1.55-2.98 GHz 대역에서 7 dBi 이상의 이득을 갖는 SDPA를 설계하였다. 성능 검증을 위해 제안된 SDPA를 $90mm(L){\times}135mm(W)$의 크기로 FR4 기판 위에 제작하였다. 제작된 안테나는 전압 정재파비(voltage standing wave ratio; VSWR)가 2 이하인 대역이 1.56-3.10 GHz으로 나왔다. 또한 1.54-3.00 GHz 대역에서 이득이 7 dBi 이상을 유지하는 것을 확인하였다.

• 정보처리학회논문지C
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• 제11C권6호
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• pp.835-842
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• 2004

본 논문에서는 다중 경고 페이딩 환경 하에서 최적의 다이버시티 기법 중 하나로 알려진 하이브리드 SC/MRC(Selective Combining/Maximal Ratio Combining) (2/3) 기법을 적용하고, 각 경로를 통해 들어오는 수신 신호와 수신기 내의 PLL(Phase Locked Loop)에서 발생된 참조 신호와의 위상차를 위상 에러로 가정한 후, PLL 루프 내의 이득 값을 조정하여 완전 동기 된 수신 신호가 되는 MC-DS/CDMA(Multi-Carrier Direct Sequence/Code Division Multiple Access) 시스템을 분석하였다. 또한, 이동 통신 환경에 대한 채널 모델로 나카가미-m 페이딩 채널 환경을 채택하였으며, 하이브리드 SC/MRC-(2/3) 다이버시티 방식이 적용된 MC/DS-CDMA 시스템에서 고려 사항인 나카가미 페이딩 지수(m), 경로의 수$(L_p),$ 하이브리드 SC/MRC-(2/3) 다이버시티 브랜치 수$(L,\;L_c),$ 사용자 수(K), 부반송파의 수(U), PLL 루프 내의 이득 값 등을 고려하여 수식을 전개하고 시뮬레이션을 수행하였다. 시뮬레이션 결과, 하이브리드 SC/MRC-(2/3) 방식이 적용된 MC/DS-CDMA 시스템에서 완전 동기 된 수신 신호를 수신할 수 있도록 하기 위해 적절한 PLL 루프 이득 값을 조절하여 성능의 개선을 이룰 수 있음을 확인할 수 있었으며 완전 동기 된 수신 신호가 되기 위해 페이딩 지수와 부반송파 확산이득에 따라 조금의 차이는 있지만 PLL 루프 이득 값이 7dB 이상 되어야 각 경로의 수신 신호가 완전 동기 된 수신 신호임을 확인하였다.

• 한국전자통신학회논문지
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• 제14권3호
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• pp.461-466
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• 2019

본 논문에서는 일반적인 마이크로스트립 안테나의 이득을 넓히기 위해 많이 사용되는 적층형 구조에 이중 급전과 L형 인셋 급전 선로 매칭회로를 이용하여 이득 및 대역폭 특성을 개선하는 연구를 하였다. 제안된 구조는 주패치 안테나의 두 개의 방사 에지(edge)에 각각 L 모양의 인셋 급전회로를 갖는 급전 선로를 연결한 구조이다. 그리고 기생패치는 주패치 위에 적절한 거리를 두고 놓여 있는 구조이다. 주패치의 크기는 공진주파수가 목표로 하는 주파수 대역의 중심 주파수에 근접하도록 설계한다. 측정 결과 단일 급전보다 관심 있는 2.3~2.7GHz 대역에서 대역폭은 180MHz 이상 증가되었고 2.7Ghz에서 최대 2.5dBi의 이득 향상을 얻을 수 있었다.

• Journal of Positioning, Navigation, and Timing
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• 제12권2호
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• pp.101-111
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• 2023

Many spoofing detection studies have been conducted to cope with the most difficult types of deception among various disturbances of GPS, such as jamming, spoofing, and meaconing. In this paper, we propose a spoofing detection scheme based on elevation masked-relative received power between GPS L1 and L2 signals in a system using a multi-band array antenna. The proposed scheme focuses on enabling spoofing to be normally detected and minimizes the possibility of false detection in an environment where false alarms may occur due to pattern distortion among elements of an array antenna. The pattern distortion weakens the GPS signal strength at low elevation. It becomes confusing to detect a spoofing signal based on the relative power difference between GPS L1 and L2, especially when GPS L2 has weak signal strength. We propose design parameters for the relative power threshold including beamforming gain, the minimum received power difference between L1 and L2, and the patch antenna gain difference between L1 and L2. In addition, in order to eliminate the weak signal strength of GPS L2 in the spoofing detection process, we propose a rotation matrix that sets the elevation mask based on platform coordinates. Array antennas generally do not have high usefulness in commercial areas where receivers are operated alone, but are considered essential in military areas where GPS receivers are used together with signal processing for beamforming in the direction of GPS satellites. Through laboratory and live sky tests using the device under test, the proposed scheme with an elevation mask detects spoofing signals well and reduces the probability of false detection relative to that without the elevation mask.