• Title, Summary, Keyword: direct-sampling method

Search Result 181, Processing Time 0.063 seconds

Structure of Direct RF Sampling Receivers for GNSS Signals

  • Won, Yu-Jun;Ahn, Woo-Hyun;Lee, MinJoon;Park, Chansik;Seo, Bo-Seok
    • Journal of Positioning, Navigation, and Timing
    • /
    • v.3 no.3
    • /
    • pp.91-97
    • /
    • 2014
  • A direct RF sampling method refers to a technique that directly converts a passband signal to an intermediate band or a baseband without using a mixer. This method is less complicated than an existing RF receiver because a mixer is not used. It uses digital processing after sampling, and thus can flexibly process signals in a number of bands using software. In this process, it is important to select an appropriate sampling frequency so that a number of signals can be converted to an intermediate band that is easy to process. In this study, going beyond previously studied direct RF sampling frequency selection methods, conditions that need to be additionally considered during receiver design were examined, and the structure of a direct RF sampling receiver that satisfies these conditions was suggested.

A Comparative Study Between Light Extinction and Direct Sampling Methods for Measuring Volume Fractions of Twin-Hole Sprays Using Tomographic Reconstruction

  • Lee, Choong-Hoon
    • Journal of Mechanical Science and Technology
    • /
    • v.17 no.12
    • /
    • pp.1986-1993
    • /
    • 2003
  • The spatially resolved spray volume fractions from both line-of-sight data of direct measuring cells and a laser diffraction particle analyzer (LDPA) are tomographically reconstructed by the Convolution Fourier transformation, respectively. Asymmetric sprays generated from a twin-hole injector are tested with 12 equiangular projections of measurements. For each projection angle, a line-of-sight integrated injection rate was measured using a direct sampling method and also a liquid volume fraction from a set of line-of-sight Fraunhofer diffraction measurements was measured using a light extinction method. Interpolated data between the projection angles effectively increase the number of projections, significantly enhancing the signal-to-noise level in the reconstructed data. The reconstructed volume fractions from the direct sampling cells were used as reference data for evaluating the accuracy of the volume fractions from the LDPA.

Chorionic villus sampling

  • Shim, Soon-Sup
    • Journal of Genetic Medicine
    • /
    • v.11 no.2
    • /
    • pp.43-48
    • /
    • 2014
  • Chorionic villus sampling has gained importance as a tool for early cytogenetic diagnosis with a shift toward first trimester screening. First trimester screening using nuchal translucency and biomarkers is effective for screening. Chorionic villus sampling generally is performed at 10-12 weeks by either the transcervical or transabdominal approach. There are two methods of analysis; the direct method and the culture method. While the direct method may prevent maternal cell contamination, the culture method may be more representative of the true fetal karyotype. There is a concern for mosaicism which occurs in approximately 1% of cases, and mosaic results require genetic counseling and follow-up amniocentesis or fetal blood sampling. In terms of complications, procedure-related pregnancy loss rates may be the same as those for amniocentesis when undertaken in experienced centers. When the procedure is performed after 9 weeks gestation, the risk of limb reduction is not greater than the risk in the general population. At present, chorionic villus sampling is the gold standard method for early fetal karyotyping; however, we anticipate that improvements in noninvasive prenatal testing methods, such as cell free fetal DNA testing, will reduce the need for invasive procedures in the near future.

Atmospheric Bioaerosol, Bacillus sp., at an Altitude of 3,500 m over the Noto Peninsula: Direct Sampling via Aircraft

  • Kobayashi, Fumihisa;Morosawa, Shinji;Maki, Teruya;Kakikawa, Makiko;Yamada, Maromu;Tobo, Yutaka;Hon, Chun-Sang;Matsuki, Atsushi;Iwasaka, Yasunobu
    • Asian Journal of Atmospheric Environment
    • /
    • v.5 no.3
    • /
    • pp.164-171
    • /
    • 2011
  • This work focuses on the analysis of bioaerosols in the atmosphere at higher altitudes over Noto Peninsula, Japan. We carried out direct sampling via aircraft, separated cultures, and identified present isolates. Atmospheric bioaerosols at higher altitudes were collected using a Cessna 404 aircraft for an hour at an altitude of 3,500 m over the Noto Peninsula. The aircraft-based direct sampling system was devised to improve upon the system of balloon-based sampling. In order to examine pre-existing microorganism contamination on the surface of the aircraft body, bioaerosol sampling was carried out just before takeoff using the same method as atmospheric sampling. Identification was carried out by a homology search for 16S or 18S rDNA isolate sequences in DNA databases (GenBank). Isolate sampling just before takeoff revealed Stretpomyces sp., Micrococcus sp., and Cladosporium sp. One additional strain, Bacillus sp., was isolated from the sample after bioaerosol collection at high altitude. As the microorganism contamination on the aircraft body before takeoff differed from that while in the air, the presence of additional, higher atmosphere-based microorganisms was confirmed. It was found that Bacillus sp. was floating at an altitude of 3,500 m over Noto Peninsula.

Modified Direct-Sampling GLC Method to Study Warmed-Over Flavor Related Volatiles (휘발성(揮發性) Warmed-Over Flavor의 연구(硏究)를 위한 변형(變形)된 Direct Sampling GLC법(法))

  • Shin-Lee, Seung-Yee;Rhee, Chong-Ouk
    • Korean Journal of Food Science and Technology
    • /
    • v.22 no.5
    • /
    • pp.562-568
    • /
    • 1990
  • The modified direct GLC method was evaluated for analysis of volatile compounds associated with WOF of cooked meat. This modified method was pertaining to collection of volatiles from the samples that contain quantities of water. The modification was appropriate for the studies of low molecular weight saturated aldehydes (C5-C15), unsaturated aldehydes (C5-C9), and saturated alcohols (C5-C9).

  • PDF

UNCERTAINTY PROPAGATION ANALYSIS FOR YONGGWANG NUCLEAR UNIT 4 BY MCCARD/MASTER CORE ANALYSIS SYSTEM

  • Park, Ho Jin;Lee, Dong Hyuk;Shim, Hyung Jin;Kim, Chang Hyo
    • Nuclear Engineering and Technology
    • /
    • v.46 no.3
    • /
    • pp.291-298
    • /
    • 2014
  • This paper concerns estimating uncertainties of the core neutronics design parameters of power reactors by direct sampling method (DSM) calculations based on the two-step McCARD/MASTER design system in which McCARD is used to generate the fuel assembly (FA) homogenized few group constants (FGCs) while MASTER is used to conduct the core neutronics design computation. It presents an extended application of the uncertainty propagation analysis method originally designed for uncertainty quantification of the FA FGCs as a way to produce the covariances between the FGCs of any pair of FAs comprising the core, or the covariance matrix of the FA FGCs required for random sampling of the FA FGCs input sets into direct sampling core calculations by MASTER. For illustrative purposes, the uncertainties of core design parameters such as the effective multiplication factor ($k_{eff}$), normalized FA power densities, power peaking factors, etc. for the beginning of life (BOL) core of Yonggwang nuclear unit 4 (YGN4) at the hot zero power and all rods out are estimated by the McCARD/MASTER-based DSM computations. The results are compared with those from the uncertainty propagation analysis method based on the McCARD-predicted sensitivity coefficients of nuclear design parameters and the cross section covariance data.

A Complex Bandpass Sampling Method for Downconversion of Multiple Bandpass Signals (다중 대역통과 신호의 하향변환을 위한 Complex Bandpass Sampling 기법)

  • Bae, Jung-Hwa;Ha, Won;Park, Jin-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.30 no.9C
    • /
    • pp.913-921
    • /
    • 2005
  • A complex bandpass sampling technique can provide a more flexible architecture for designing a software- defined radio(SDR) system, because it has several advantageous features of larger sampling range and lower minimum sampling frequency than a real bandpass sampling method. In spite of the potential advantages of the complex bandpass sampling, solid investigation for the direct downconversion of multiple signals by the complex sampling theory has not been reported yet. Thus, we propose in this paper a novel scheme for the downconversion of multiple signals using the complex bandpass sampling, and develop the formulae related to the complex bandpass sampling for practical usage, such as the valid sampling range, the intermediate frequency (If), and the minimum sampling frequency of the downconversion of multiple RE signals. Such derived formulae are verified from simulations.

Study on Sampling Techniques for Digital Elevation Model (수치표고모형에 있어서 표고추출법의 연구)

  • Kang, In-Joon;Jung, Jae-Hyung;Kwak, Jae-Ha
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
    • /
    • v.10 no.2
    • /
    • pp.49-55
    • /
    • 1992
  • Sampling techniques is very important in digital elevation model. There are scanning and digitizing method of sampling techniques. This study is limited in digitizing method. Continous sampling method use contour lines as same entity and grid method is a direct reading of sample elevation in each grid. Triangulated irregular method is needed to identity topographical lines to sample elevation data. As a results, authors know that continous sampling method has economic in input system and triangulated irregular method has a small memory size.

  • PDF

A Direct Torque Control Characteristics of SRM using PWM Approach (PWM 기법을 적용한 SRM의 직접토크 제어 특성)

  • Lee, Dong-Hee;Wang, Huijun;Ahn, Jin-Woo
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.13 no.3
    • /
    • pp.179-185
    • /
    • 2008
  • In this paper, an advanced torque control scheme of SRM using DITC(Direct Instantaneous Torque Control) and PWM(pulse width modulation) is presented. Different from conventional DITC method, proposed method uses one or two switching modes at every sampling time, instead of only one switching mode. The duty ratio of the phase switch is regulated according to the torque error and simple control rules of DITC. Moreover the sampling time of control can be extended, which allows implementation on low cost micro-controllers. A simple calculation of PWM can assure a constant switching frequency with an excellent control performance. The proposed control method is verified by the simulations and experimental results.

Torque Ripple Reduction Scheme of SRM using Advanced Direct Instantaneous Torque Control Method (개선된 직접순시토크제어기법을 이용한 SRM의 토크리플 저감기법)

  • Ahn, Jin-Woo;Lee, Dong-Hee;Wang, Huijun;Seck, Sung-Hun
    • Proceedings of the KIEE Conference
    • /
    • /
    • pp.135-137
    • /
    • 2007
  • In this paper, an advanced torque control scheme of SRM using DITC(Direct Instantaneous Torque Control) and PWM(pulse width modulation) is presented. Different from conventional DITC method, proposed method uses one or two switching modes at every sampling time, instead of only one switching mode. The duty ratio of the phase switch is regulated according to the torque error and simple control rules of DITC. Moreover the sampling time of control can be extended, which allows implementation on low cost microcontrollers. The proposed control method is verified by the simulations and experimental results.

  • PDF