• Journal of Positioning, Navigation, and Timing
• /
• 제3권3호
• /
• 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.

• Journal of Mechanical Science and Technology
• /
• 제17권12호
• /
• 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.

• Journal of Genetic Medicine
• /
• 제11권2호
• /
• 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.

• 한국식품과학회지
• /
• 제22권5호
• /
• pp.562-568
• /
• 1990

조리(調理) 육류(肉類)의 WOF와 관련(關聯)된 휘발성(揮發性) 성분(成分)을 분석(分析)하기 위하여 변형(變形)된 Direct GLC 방법(方法)을 이용(利用)하였다. 이 변형(變形)된 방법(方法)은 기존(旣存)의 다른 방법(方法)과는 달리 수분함량(水分含量)이 많은 시료(試料)로부터 휘발성(揮發性) 성분(成分)을 분리(分離)하는데 유용(有用)하였으며, 특히 저분자량(低分子量)의 포화(飽和) $aldehyde\;(C_c-C_{15})$류(類), 불포화(不飽和)$aldehyde(C_5{\sim}C_9)$류(類)의 연구(硏究)에 적절한 것으로 판명(判明)되었다.

• Nuclear Engineering and Technology
• /
• 제46권3호
• /
• 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.

• 한국통신학회논문지
• /
• 제30권9C호
• /
• pp.913-921
• /
• 2005

일반적인 bandpass sampling 방법인 real bandpass sampling 기법은 하향변환(downconversion)을 시행할 때 음의 주파수 대역의 RF 신호와의 에일리어싱(aliasing) 현상을 피해야 하므로 신중한 sampling 주파수 선택이 요구된다. 더욱이 다중신호(multiple signals)가 하향변환 될 경우에 이 sampling 방법은 더욱 많은 제약이 따르게 된다. 그러나 Hilbert 변환을 사용하는 complex bandpass sampling 방법은 음의 주파수 영역의 신호를 제거함으로써, real bandpass sampling 기법보다 유연하고 넓은 sampling 주파수 범위를 제공하며, 또한 더욱 낮은 sampling 주파수를 얻을 수 있는 장점이 있다. 본 논문에서는 이러한 complex bandpass sampling의 특징을 사용하여, 다중 신호를 하나의 통신 기기에서 동시에 하향 변환하는 수신기의 구조를 제시한다. 그리고 하나 또는 2개 신호의 하향변환에 관한 내용으로 제한하지 않고 N개의 신호로 확장하여 유효 sampling 주파수 영역 및 보호대역(guard-band)이 고려된 sampling 가능 최소 주파수에 관한 수식들을 일반화한다. 또한 모의실험을 통해 유도된 수식들을 증명한다.

• 한국측량학회지
• /
• 제10권2호
• /
• pp.49-55
• /
• 1992

수피표고모형에 있어서 표고자료의 추출은 매우 중요하다. 표고의 추출은 스캐닝방법과 디지타이징 방법이 있으나 본 연구에서는 디지타이징에 대한 것이다. 연속적 추출법은 하나의 등고선을 동일한 개체로 묶는 것이며, 정규적자법은 각 격자를 대표할 수 있는 표고데이타를 직접 읽는 방법이다. 그리고 지성선을 구성하는 등고선내의 추출점을 동일의 개체로 묶는 방법이 불규칙 삼각망법이다. 연구결과에서 연속적 추출법은 입력시간이 적게 걸렸으며, 불규칙 삼각망법은 추출점의 수가 가장 적게 나타났다.

• Asian Journal of Atmospheric Environment
• /
• 제5권3호
• /
• 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.

• 웰빙융합연구
• /
• 제3권2호
• /
• pp.1-11
• /
• 2020

Purpose: We explore to find out and analyze the direct influence of Millennial Orientation on Goals Mediated by work engagement and satisfaction. And, interaction cannot be a direct relationship between research variables. Method: The implementation uses the survey method. This research was conducted at PT. East Kalimantan fertilizer operated in Bontang, East Kalimantan. The population in this study were all employees of PT. East Kalimantan fertilizers operated in Bontang, as many as N = 500 people. The sampling technique used is proportional stratified random sampling. Findings: Millennial orientation influences engagement, job satisfaction and intention to leave, direct engagement has a significant effect on job satisfaction and intention to leave, and job satisfaction is directly related to intention to leave. Originality: Alignment between millennial goals in encouraging job satisfaction and employee engagement, so that it can have an impact on the intention to leave employees, especially at PT. Pupuk. Kaltim. Also, direct millennials as decreasing intention to leave.

• 전력전자학회논문지
• /
• 제13권3호
• /
• pp.179-185
• /
• 2008

본 논문에서는 SRM의 토크리플 억제를 위하여 PWM(Pulse width modulation)과 직접토크제어(DITC, Direct Instantaneous Torque Control) 방식의 결합에 의한 제어방식을 제안하였다. 기존의 직접토크제어와 달리, 제안된 방식은 한 샘플링 구간 내에서 하나 또는 두 개의 스위칭 모드로 동작하며, 스위칭 패턴의 폭은 토크 오차와 직접 토크제어 방식의 제어규칙에 따라 제어된다. 또한 실제 스위치의 제어폭이 토크 오차에 따라 가변적으로 제어됨으로써, 같은 샘플링 주기에서 기존의 직접토크제어 방식에 비하여 토크리플을 크게 억제할 수 있으며, 토크 연산의 샘플링 주기를 크게 할 수도 있는 장점이 있다. 간단한 제어규칙과 PWM 듀티비의 계산으로 복잡한 연산이 요구되지 않으므로 저가의 마이크로 프로세서에 의해 구현이 가능하다. 제안된 방식은 컴퓨터 시뮬레이션과 실험을 통하여 검증하였다.