• Animal Bioscience
• /
• 제34권5호
• /
• pp.886-894
• /
• 2021

Objective: An experiment was conducted to study the effect of graded concentration of digestible lysine (dLys) on performance of layers fed diets containing sub-optimal level of protein. Methods: Five diets were formulated to contain graded concentrations of dLys (0.700%, 0.665%, 0.630%, 0.593%, and 0.563%), but similar levels of crude protein (15% CP), energy (10.25 MJ ME/kg) and other nutrients. A total of 3,520 hens (26 wk of age) with mean body weight of 1,215+12.65 g were randomly divided into 40 replicate groups of 88 birds in each and housed in an open sided colony cage house. Each diet was offered ad libitum to eight replicates from 27 to 74 wk of age. The performance was compiled at every 28 d and the data for each parameter were grouped into three phases, that is early laying phase (27 to 38 wk), mid laying phase (39 to 58 wk), and late laying phase (59 to 74 wk of age) for statistical analysis. Results: Egg production, egg mass and feed efficiency (feed required to produce an egg) were significantly improved by the dLys level during the early and mid laying phases but not during the late phase. Whereas feed intake was significantly reduced by dLys concentration during mid and late laying phases but not during early laying phase. The egg weight was not affected by dLys concentration in any of the three phases. Conclusion: Based on best fitted statistical models, dietary requirements of dLys worked out to be 0.685%, 0.640%, and 0.586% during early phase, mid phase, and late egg laying phase, respectively. The calculated requirement of dLys for the respective production phases are 727 mg/b/d during the early and mid laying phases and 684 mg/b/d during the late laying phase in diets containing 15% CP.

• 한국통신학회논문지
• /
• 제26권12B호
• /
• pp.1733-1740
• /
• 2001

A monolithic 5 GHz image reject mixer using a 0.5-m GaAs MESFET technology is designed and simulated. The Mixer exhibits a 13.56 dB down-conversion gain, a SSB (Single SideBand) noise figure of 11.91 dB, an input IP3 (third order intercept point) of -3.73 dBm and a PldB (1-dB compression point) of -11.0 dBm. The critical issue in the image reject mixer is the phase accuracy and magnitude balance of the 90 phase shifting network. The proposed image reject mixer realizes a 90 phase shifter on chip. This phase shifting network does not need any phase adjusting to achieve the phase error specification of 3 over a frequency range from 800 MHz to 1GHz. The simulated overall image rejection ratio is better than 50 dB.

• 한국전자파학회논문지
• /
• 제20권9호
• /
• pp.967-973
• /
• 2009

본 논문에서는 두 개의 위상 동기 루프를 구성하여 이중으로 위상 고정시킨 band 위성통신용 국부 발진기를 설계하고 위상 잡음을 분석하였다. 설계된 위상 동기 발진기는 직렬귀환 유전체 공진발진기, 주파수 분주기, 위상검출기, 루프 필터 및 PLL-IC로 구성되어 있으며, 12.6 GHz의 발진 주파수를 2분주시켜 6.3 GHz에서 15.32 dBm의 출력값을 보였다. 제작한 발진기의 위상 잡음은 -81 dBc/Hz@100 Hz, -100.86 dBc/Hz@1 kHz, -111.12 dBc/Hz@10 kHz, -116 dBc/Hz@100 kHz 및 -140.49 dBc/Hz@1 MHz으로 매우 안정되며 우수한 특성을 보였다.

• 한국정보통신학회논문지
• /
• 제26권8호
• /
• pp.1188-1195
• /
• 2022

6-단자 위상 상관기는 동위상 전력 분배기 한 개와 3-dB 90도 위상차 전력 분배기 세 개로 구성된 회로로 입력 신호의 위상을 판별하는 복조 회로에 주로 사용된다. 본 논문에서는 37.5-Ω 동축선 3개를 이용한 광대역 2:1 임피던스 변환 회로 구조의 동위상 전력 분배기와 Wireline 이용한 3-dB 90도 위상차 전력 분배기를 사용하여 광대역에서 동작하는 6-단자 위상 상관기를 제안하였다. 중심 주파수 1000MHz에서 제작된 제안된 광대역 6-단자 위상 상관기는 640~1270MHz 주파수 범위에서 동위상 전력 분배기 입력 신호에 대한 4개의 출력 단자로의 신호 전달 특성(S_i1)은 세기 -6.5±0.6dB와 위상 오차 ±3.4° 이내, 90도 위상차 전력 분배기 입력 신호에 대한 신호 전달 특성(S_i2)은 세기 -6.1±0.6dB와 위상 오차 ±6.2° 이내, 입력 반사계수(S₁₁ and S₂₂) -14dB 이하의 안정적인 값을 가졌다.

• 대한전자공학회논문지TC
• /
• 제39권3호
• /
• pp.158-164
• /
• 2002

2-6 GHz 디지털 위상변위기 모듈을 설계, 제작하였다. 위상변위기 모듈에 사용된 MMIC 칩은 광대역을 구현하기 위해 Lange 커플러로 구성된 반사형 회로를 이용하여 설계 및 제작하였다. 위상변위기 모듈은 6.1°RMS 위상오차, 13.5 dB 최대 삽입손실과 각각, 8 dB와 10 dB의 입·출력 반사손실 특성을 갖는다. 32개의 위상 상태를 측정하기 위해서 컴퓨터를 사용하여 측정을 자동화 시켰다. 8×8 위상배열용 모듈들간의 RMS 삽입 위상오차는 최대 ±0.5°이내이고, 모듈들간의 평균 삽입손실 편차는 최대 ±0.5 dB를 넘지 않았다. 제작된 위상변위기 모듈의 크기는 45 × 22.5 × 60 ㎣. 이다.

• 한국전자파학회논문지
• /
• 제10권6호
• /
• pp.816-824
• /
• 1999

본 논문에서는 아날로그 위상비교기률 이용한 위상고정루프를 소개하였으며. 이 방법을 이용하여 20 GHz 대 고정국용 위상고정 국부발진기를 설계 제작하였다. 이 국부발진기는 하이브리드 형태의 18 GHz VCDRO (Voltage Controlled Dielectric Resonator Oscillator)와 완충증폭기 및 아날로그 위상검출기로 이루어져 있다. 일반적인 크리스탈 발전기의 N배 이외의 주파수를 위상고정하기 위하여 VHF PLL로 구성되어 있다. 국부발 진기의 발진전력은 18 GHz에서 약 21 dBm. 고조파억압은 - 34 dBc로 안정된 위상고정 상태를 나타내었다. 이때의 SSB위상잡음은 -75 dBc/Hz@10 kHz로 측정되었다.

• Journal of the Optical Society of Korea
• /
• 제5권3호
• /
• pp.99-109
• /
• 2001

This paper presents a phase-only modulation scheme for a three-dimensional (3-D) image matching system to improve optical efficiency of the system. The 3-D image matching system is based on the two mask heterodyne scanning. A hologram of the 3-D reference object is first created and then the phase of the hologram is extracted. The phase of the hologram is represented as one mask with the other mask being a plane wave. The superposition of each beam modulated by the two masks generated a scanning beam pattern. This beam pattern scans the 3-D target object to be recognized. The output of the scanning system gives out the correlation of the phase-only hologram of the reference object and the complex hologram of the target object. Since a hologram contains 3-D information of an object as a form of fringe pattern, the correlation of holograms matches whole 3-D aspect of the objects. Computer simulations are performed with additive gaussian noise and without noise for the complex hologram modulation scheme and the phase-only hologram modulation scheme. The computer simulation results show that the phase-only hologram modulation scheme improves the optical efficiency. Thus the system with the phase-only hologram modulation scheme is more robust than the system with the complex hologram modulation scheme.

• Bulletin of the Korean Chemical Society
• /
• 제31권2호
• /
• pp.372-378
• /
• 2010

Membrane disruption by an antimicrobial peptide, protegrin-1 (PG-1), was investigated by measuring the $^2H$ solid-state nuclear magnetic resonance (SSNMR) spectra of 1-palmitoyl-$d_{31}$-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC_$d_{31}$) in the mixture of PG-1 and POPC_$d_{31}$ lipids deposited on thin cover-glass plates. The experimental line shapes of anisotropic $^2H$ SSNMR spectra measured at various peptide-to-lipid (P/L) ratios were simulated reasonably by assuming the mosaic spread of bilayers containing pore structures or the coexistence of the mosaic spread of bilayers and a fast-tumbling isotropic phase. Within a few days of incubation in the hydration chamber, the pores were formed by the peptide in the POPC_$d_{31}$ and POPC_$d_{31}$/cholesterol membranes. However, the formation of the pores was not clear in the POPC_$d_{31}$/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol (POPG) membrane. Over a hundred days after hydration, a rapidly rotating isotropic phase increased in the POPC_$d_{31}$ and the POPC_$d_{31}$/cholesterol membranes with the higher P/L ratios, but no isotropic phase appeared in the POPC_$d_{31}$/POPG membrane. Cholesterol added in the POPC bilayer acted as a stabilizer of the pore structure and suppressed the formation of a fast-tumbling isotropic phase.

• 한국전자파학회논문지
• /
• 제13권6호
• /
• pp.552-559
• /
• 2002

본 논문에서 는 Ka-band 위 성 중계 기용 국부발진기 의 EM(Engineering Model)을 설계 및 제작하였다. 루프 대역 밖의 위상잡음을 개선하기 위해서 고임피던스 변환기를 이용한 낮은 위상잡음의 전압제어 발진기를 설계하고 샘플링위상비교기(Sampling Phase Detector)를 사용하여 전압제어 발진기를 고안정의 OCXO(Oven Controlled Crystal Oscillator)에 위상 고정시킴으로써 루프 대역 내의 위상잡음을 개선하였다. 개발된 국부발진기는 43.83 dBc 이상의 고조파 억압특성을 가지고 있으며 공급전력은 15 V, 160 mA를 필요로 한다. 위상잡음은 -102.5 dBc/Hz @10 KHz와 -104.0 dBc/Hz @100 KHz의 특성을 나타내며 출력전력은 -20 - +7$0^{\circ}C$의 온도 범위에서 13.50 dBm$\pm$0.33 dB의 특성을 얻었다.

• International Journal of Advanced Culture Technology
• /
• 제10권3호
• /
• pp.339-345
• /
• 2022

In this paper, the effect of porosity on the acoustic phase velocity of the 3D printed Kelvin closed-cell structure was investigated using the spectral phase analysis. Since Kelvin cells bring about the large amount of scattering, acoustic pulses in ultrasonic measurements undergoes a distortion of waveforms due to the dispersion effect. In order to take account on the dispersion, mathematical expressions for calculating the phase velocity of longitudinal waves propagating normal to the plane of the Kelvin structure are suggested by introducing a complex wave number based on Fourier transform. 3D Kelvin structure composed of identical unit-cells, a polyhedron of 14 faces with 6 quadrilateral and 8 hexagonal faces, was developed and fabricated by 3D CAD and 3D printer to represent the micro-structure of porous materials such as aluminum foam and cancellous bone. Total nine samples of 3D Kelvin structure with different porosity were made by changing the thickness of polyhedron. Ultrasonic pulse of 1MHz center frequency was applied to the Kelvin structures for the measurement of the phase velocity of ultrasound using the TOF(time-of-flight) and the phase spectral method. From the experimental results, it was found that the acoustic phase velocity decreased linearly with the porosity.