• Communications for Statistical Applications and Methods
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• 제24권3호
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• pp.241-254
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• 2017

Drawing a sample can be costly or time consuming in some studies. However, it may be possible to rank the sampling units according to some baseline auxiliary covariates, which are easily obtainable, and/or cost efficient. Ranked set sampling (RSS) is a method to achieve this goal. In this paper, we propose a modified approach of the RSS method to allocate units into an experimental study that compares L groups. Computer simulation estimates the empirical nominal values and the empirical power values for the test procedure of comparing L different groups using modified RSS based on the regression approach in analysis of covariance (ANCOVA) models. A comparison to simple random sampling (SRS) is made to demonstrate efficiency. The results indicate that the required sample sizes for a given precision are smaller under RSS than under SRS. The modified RSS protocol was applied to an experimental study. The experimental study was designed to obtain a better understanding of the pathways by which positive experiences (i.e., goal completion) contribute to higher levels of happiness, well-being, and life satisfaction. The use of the RSS method resulted in a cost reduction associated with smaller sample size without losing the precision of the analysis.

• 융합정보논문지
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• 제8권1호
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• pp.123-130
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• 2018

본 연구의 대상은 경상북도 문경시 시민으로 생활체육동호회 회원을 모집단으로 선정할 후 현재 각 동호회에 소속되어 있는 250명을 모집선정 하였다. 자료를 위한 표본추출방법은 단순임의추출(Simple ramdom sampling)방법을 이용하였으며, 자기평가기입법(Self-administrarion method)에 의거하여 설문지 작성 후 배포 및 회수 하였다. 이중 설문내용의 신뢰성 결여(이중기입, 무기입, 부실자료 등)되었다고 판단되는 50부를 제외한 총 200부의 설문지를 대상으로 분석하였다. 자료 분석을 위하여 본 연구에서 사용한 분석법은 빈도분석, ${\chi}^2$, 요인분석, 신뢰도 분석, 일원변량분석을 실시하여 다음과 같은 연구결과를 도출하였다. 첫째, 연령대별 운동참여자들의 생활만족도는 유의한 차이가 없었다. 둘째, 학력에 따른 운동참여자들의 생활만족도는 통계적으로 유의한 차이가 있었다.

• 한국지진공학회논문집
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• 제7권4호
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• pp.81-87
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• 2003

본 논문에서는 Shannon의 샘플링 이론을 이용하여 제한된 수의 센서에서 얻은 모드형상으로 정확한 모드형상을 재생성하고, 이렇게 재생성한 모드형상을 이용하여 구조물에 발생한 손상을 탐지할 수 있는지의 가능성에 대해 조사하였다. 우선 시간 영역에서의 Shannon의 샘플링 이론을 검토하였고, 이를 공간영역으로 확대하였다. 공간영역으로 확대한 Shannon의 샘플링 이론은 그 효용성을 확인하기 위하여 단순보의 모드형상을 해석적으로 구한 후 최소한으로 제한된 수의 샘플 데이터로 모드형상을 재생하였고 이를 원래의 모드형상과 비교하였다. 이렇게 하여 얻은 결과를 바탕으로 구조물의 모드형상을 추출하는 동적실험에서 필요한 최적 가속도계의 위치를 구할 수 있는 간단한 관계식을 제안하였다. 제안된 관계식과 공간영역으로 확대한 Shannon의 샘플링 이론의 실용성은 연속 2스팬으로 구성된 실험실 빔 구조물의 손상 전과 후의 모드형상에 적용하여 손상을 탐지함으로써 입증하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.385-390
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• 2006

This paper examines the sampling and jitter specifications and considerations for Global Navigation Satellite Systems (GNSS) software receivers. Software radio (SWR) technologies are being used in the implementation of communication receivers in general and GNSS receivers in particular. With the advent of new GPS signals, and a range of new Galileo and GLONASS signals soon becoming available, GNSS is an application where SWR and software-defined radio (SDR) are likely to have an impact. The sampling process is critical for SWR receivers, where it occurs as close to the antenna as possible. One way to achieve this is by BandPass Sampling (BPS), which is an undersampling technique that exploits aliasing to perform downconversion. BPS enables removal of the IF stage in the radio receiver. The sampling frequency is a very important factor since it influences both receiver performance and implementation efficiency. However, the design of BPS can result in degradation of Signal-to-Noise Ratio (SNR) due to the out-of-band noise being aliased. Important to the specification of both the ADC and its clocking Phase- Locked Loop (PLL) is jitter. Contributing to the system jitter are the aperture jitter of the sample-and-hold switch at the input of ADC and the sampling-clock jitter. Aperture jitter effects have usually been modeled as additive noise, based on a sinusoidal input signal, and limits the achievable Signal-to-Noise Ratio (SNR). Jitter in the sampled signal has several sources: phase noise in the Voltage-Controlled Oscillator (VCO) within the sampling PLL, jitter introduced by variations in the period of the frequency divider used in the sampling PLL and cross-talk from the lock line running parallel to signal lines. Jitter in the sampling process directly acts to degrade the noise floor and selectivity of receiver. Choosing an appropriate VCO for a SWR system is not as simple as finding one with right oscillator frequency. Similarly, it is important to specify the right jitter performance for the ADC. In this paper, the allowable sampling frequencies are calculated and analyzed for the multiple frequency BPS software radio GNSS receivers. The SNR degradation due to jitter in a BPSK system is calculated and required jitter standard deviation allowable for each GNSS band of interest is evaluated. Furthermore, in this paper we have investigated the sources of jitter and a basic jitter budget is calculated that could assist in the design of multiple frequency SWR GNSS receivers. We examine different ADCs and PLLs available in the market and compare known performance with the calculated budget. The results obtained are therefore directly applicable to SWR GNSS receiver design.

• Advances in aircraft and spacecraft science
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• 제6권6호
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• pp.529-550
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• 2019

The effect of multiple process parameters on a set of continuous response variables is, especially in experimental designs, difficult and intricate to determine. Due to the complexity in aeroacoustic and vibroacoustic studies, the often-performed simple one-factor-at-a-time method turns out to be the least effective approach. In contrast, the statistical Design of Experiments is a technique used with the objective to maximize the obtained information while keeping the experimental effort at a minimum. The presented work aims at giving insights on Design of Experiments applied to aeroacoustic and vibroacoustic problems while comparing different experimental designs and approximation models. For this purpose, an experimental rig of a ducted low-pressure fan is developed that allows gathering data of both, aerodynamic and aeroacoustic nature while analysing three independent process parameters. The experimental designs used to sample the design space are a Central Composite design and a Box-Behnken design, both used to model a response surface regression, and Latin Hypercube sampling to model an Artificial Neural network. The results indicate that Latin Hypercube sampling extracts information that is more diverse and, in combination with an Artificial Neural network, outperforms the quadratic response surface regressions. It is shown that the Latin Hypercube sampling, initially developed for computer-aided experiments, can also be used as an experimental design. To further increase the benefit of the presented approach, spectral information of every experimental test point is extracted and Artificial Neural networks are chosen for modelling the spectral information since they show to be the most universal approximators.

• Asian Pacific Journal of Cancer Prevention
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• 제16권12호
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• pp.4971-4975
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• 2015

Background: Several methods have been presented for the evaluation of the endometrium in patients with abnormal uterine bleeding, which include minimal invasive and invasive approaches such as diagnostic curettage or endometrial biopsy by Pipelle. Many studies have been performed in order to compare two methods; diagnostic curettage and outpatient endometrial biopsy. This investigation compared sampling adequacy, endometrial histopathology, failure rates, duration and costs between diagnostic curettage in a hospital and endometrial biopsy. Materials and Methods: This single blind clinical trial was performed on 130 patients older than 35 years who was referred to Amir training hospital in 2013 for elective diagnostic curettage because of abnormal uterine bleeding. For all patients eligible for the study, an endometrial sample by Pipelle was taken without anesthesia or dilatation. Then under general anesthesia diagnostic curettage was performed by sharp curette. Sampling duration was calculated and both samples were sent to the same pathologist. The diagnostic values of two methods in the diagnosis of normal endometrium, endometrial hyperplasia and carcinoma were compared. The costs of these two methods were also compared. Data analysis was performed by SPSS (version 16.0) software. Chi-Square, Fisher, and Pearson tests were used and were considered statistically significant at P values less than 0.05. Results: Two methods were agreed upon 88% of sampling adequacy and 94% of pathological results. Specificity of 100% and sensitivity of 90% for detection of proliferative endometrium, secretory endometrium, simple hyperplasia without atypia and 100% for cancer were recorded. Pipelle diagnostic accuracy in comparison with curettage, have been reported over 97%, so the failure rate in this study was below 5%. Sensitivity of Pipelle for detection of atrophic endometrium was reported below 50%. Duration and cost was lower in Pipelle versus curettage. Conclusions: It is concluded that due to high agreement and cohesion coefficient between curettage and Pipelle on the issue of sampling adequacy, histopathology finding (except atrophic endometrium), low failure rate, duration of sampling and cost, Pipelle can be introduced as a suitable alternative of diagnostic curettage.

• 품질경영학회지
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• 제17권1호
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• pp.69-81
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• 1989

This study is concerned with a job sequencing method using the concept of sampling technique in the case of Job Shop. This is the follow study of Kang and Ro (1988) which examined the possibility of application of sampling technique to determine the Job Sequence in the case of Flow Shop. Not only it is very difficult, but also it takes too much time to develop the appropriate job schedules that satisfy the complex work conditions. The most job sequencing algorithms have been developed to determine the best or good solution under the special conditions or assumptions. The application areas of these algorithms are also very narrow, so it is very hard to find the appropriate algorithm which satisfy the complex work conditions. In this case it is very desirable to develop a simple job sequencing method which can select the optimal job sequence or near optimal job sequence with a little effort. This study is to examine the effect of sampling job sequencing which can select the good job of 0.01%~5% upper good group. The result shows that there is the sets of 0.05%~23% job sequence group which has the same amount of performance measure with the optimal job sequence in the case of experiment of N/M/G/$F_{max}$. This indicates that the sampling job sequencing method is a useful job sequencing method to find the optimal or good job sequence with consuming a small amount of time. The results of ANOVA show that the only one factor, number of machines is the significant factor for determining the job sequence at ${\alpha}=0.01$. It takes about 10 minutes to compare the number of 10,000 samples of job sequence by personal computer and it is proved that the selection rate of the same job sequence with optimal job sequence is 23.0%, 3.9% and 0.065% in the case of 2 machines, 3 machines and 4 machines, respectively. The area of application can readily be extended to the other work condition.

• 대한의용생체공학회:의공학회지
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• 제23권4호
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• pp.323-327
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• 2002

만성 당뇨병 질환자는 일 2회 이상 모세혈액을 채취하여 혈당검사를 행함으로써 자신의 혈당 수준을 지속적으로 관리해야 한다. 모세혈액 채취를 위하여 채혈침으로 빈번하게 피부관통을 행해야 하므로 채혈시 뒤따르는 통증은 대단히 중요한 문제이다. 본 연구에서는 기존의 수동 및 자동 채혈침들이 가지는 통증 유발요인들을 모두 최소화하는 기전을 고안하였다. 경사각을 이루는 taper형 스프링, 채혈침을 일관성있는 방향으로 이동시키는 guiding tunnel, 현존하는 기술로 제조할 수 있는 가장 가는 30G 채혈침을 적용함으로써 통증을 최소화 하였다. 침의 침투 깊이를 피하 2mm로 제한하여 통증을 최소화하는 동시에 출혈량을 감소시켰다. 또한 환자 간 감염 및 이차 감염을 방지하기 위하여 사용이 용이한 재사용 방지기전을 설치하였다. 당뇨질환자. 일반인 및 간호실습생들을 대상으로 한 임상실험 결과 통증 및 사용편의성과 안전성 모두 우수한 것으로 입증되었다. 일회 채혈로 모두 성공적인 혈당검사가 가능하였으며 단순한 구조의 소형화 ·일체화된 일회용 자동채혈침의 형태로 구현하였다 본 연구결과는 혈담검사를 위한 모세혈액 채취시 최적의 방법을 제공하였으며 실용성 또한 우수한 것으로 판단되었다.

• 한국통신학회논문지
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• 제30권10C호
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• pp.965-975
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• 2005

본 논문에서는 향후 초고속 W-PAN(Wireless Personal Area Network)을 위한 유력한 전송 기술로서 각광받고 있는 MB-OFDM UWB(Multi-Band Orthogonal Frequency Division Multiplexing Ultra Wide Band) 시스템의 동기화를 위한 효과적인 반송파 및 샘플링 주파수 오프셋 결합 추정 기법을 제시하고 성능을 평가하였다. 이를 위해 PLCP(Physical Layer Convergence Procedure) 프리앰블 내의 채널 추정 시퀀스를 이용하고 MB-OFDM UWB 시스템 기술 규격 및 주파수 운용 방식을 고려하였으며, 반송파와 샘플링 주파수 오프셋을 결합 추정하는 방법으로서 먼저 샘플링 주파수 오프셋을 추정하고 추정된 샘플링 주파수 오프셋을 이용하여 반송파 주파수 오프셋을 추정하는 방식을 적용하였다. 또한 추정된 오프셋 값들의 신뢰도 향상을 위해 각 과정에서 가중치 기반의 주파수 오프셋 추정 기법을 사용하였다. IEEE 802.15 Task Group 3a에서 제공하는 4가지 UWB 실내 채널 모델을 이용한 모의실험 결과, 각 부채널에서의 수신 신호 평균 전력을 반영하는 제안된 간단한 형태의 가중치 기반 추정 기법의 성능이 채널의 주파수 응답을 사용하여 완벽한 채널 추정을 필요로 하는 이상적인 방법에 비해 훨씬 낮은 복잡도로 유사한 성능을 얻을 수 있음을 확인 하였다.

• 한국전자통신학회논문지
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• 제15권6호
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• pp.1023-1030
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• 2020

임의의 그래프 신호를 복원하기 위해 그래프상의 일부 노드로 구성된 샘플링 집합내의 노드들의 신호값만을 사용하게 되는 경우, 이를 위한 최적의 샘플링 집합 선택 문제에 대해 연구한다. 고도의 계산량을 요구하는 고유값 분해 (eigen decomposition)를 사용하지 않고, 노드를 선택하는 과정에서의 신호 변화값의 차이를 비용함수로 제시한다. 구체적으로, 기존 방식의 비용함수인 신호 복원오차를 최소화하는 대신에 본 연구에서는 신호 변화값의 차이를 비용함수로 채택하여 이를 최소화하는 간단하고 고속의 탐욕 (greedy) 샘플링 집합선택 알고리즘을 제안한다. 기존의 고속알고리즘과 성능평가 비교를 위해 다양한 그래프 신호에 대한 폭넓은 실험을 진행하여, 기존 방식 대비 신호복원 성능감소를 약 7% 이내로 유지하면서 실행시간을 10배이상으로 단축하였음을 보인다.