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

• 한국통신학회논문지
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• 제30권7C호
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• pp.687-695
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• 2005

차세대 통신기술인 Software-Defined Radio (SDR)시스템은 단일 하드웨어 플랫폼에 소프트웨어 변경만으로 다양한 통신표준을 수용할 수 있는 시스템이다. 시스템의 융통성(flexibility)과 적응성(adaptability)을 위하여 RF와 관련된 하드웨어의 최소화가 필요하며, 이를 위해 ADC를 사용으로 기저대역(baseband) 또는 낮은 IF단으로 직접하향 변환(downconversion)을 할 수 있는 bandpass sampling 기법이 필수적이다. 이 논문에서는 complex bandpass sampling 방식을 이용하여 두 가지의 통신 표준이 한 시스템에서 동시에 직접 하향 변환하는 새로운 방법을 제안하였다. 이에 따른 sampling 가능 영역, 보호대역(guard-band)을 고려한 sampling 가능 최소 주파수 그리고 이동된 신호의 위치를 구하는 수식들을 유도한 뒤 그래프를 통해 비교 분석하였다. 또한 제안한 sampling방식이 모의실험을 통해 기존에 제안되었던 real bandpass sampling방식보다 SDR시스템에 더욱 적합하다는 것을 입증하였다.

• 한국정보통신학회논문지
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• 제15권8호
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• pp.1805-1812
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• 2011

Bandpass sampling(BPS) 기술은 나이퀴스트(Nyquist) 샘플링 주파수보다 낮은 주파수를 사용하여 RF 대역의 신호를 직접 하향변환 할 수 있다는 장점을 가지고 있지만, 나이퀴스트 영역에서 self-image의 중복을 피하기 위해서는 샘플링 주파수의 선택에 제약이 따른다. 2개의 ADC를 사용하는 2차(second-order) BPS는 self-image를 제거하기 위한 신호처리가 추가 된다는 조건으로 샘플링 주파수의 선택이 자유롭다. 하지만 RF 대역이 바뀌면 신호처리를 위한 파라미타를 재구성해야 한다. 본 논문에서는 2차 BPS의 한 형태인 quadrature BPS의 구조를 가지면서, 재구성이 필요 없는 간단한 보상 필터만을 사용하여 임의 RF 대역으로부터 나이퀴스트 영역으로 하향 변환하는 complex BPS 기반의 SDR front-end에 대하여 기술한다.

• Communications for Statistical Applications and Methods
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• 제22권5호
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• pp.435-443
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• 2015

Two phase sampling design is useful to increase estimation efficiency using deep stratification, improved non-response adjustment and reduced coverage bias. The same sampling units are commonly used for the first and the second phases in complex two-phase sampling design. In this paper we consider a sampling scheme where the first phase sampling units are clusters and the second phase sampling units are list samples. Using selected clusters in first phase requires that we list up elements in the selected clusters from the first phase and then use the list as a secondary sampling frame for the second phase sampling design. Then we select second phase samples from the listed sampling frame. We suggest an estimator based on the complex two-phase sampling design with different sampling units of each phase. Also the estimated variances of the estimator obtained by using classic and replication variance methods are considered and compared using simulation studies. For real data analysis, 2010 Korea Farm Household Economy Survey (KFHES) and 2011 Korea Agriculture Survey (KAS) are used.

• 품질경영학회지
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• 제20권1호
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• pp.158-167
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• 1992

This paper represents the new techniques for optimal sampling plans of reliability applying the mathematical complex number(real and imaginary number) in the complex system of reliability. The research formulation represent a mathematical model Which preserves all essential aspects of the main and auxiliary factors of the research objectives. It is important to formule the problem in good agreement with the objective of the research considering the main and auxilary factors which affect the system performance. This model was repeatedly tested to determine the required statistical chatacteristics which in themselves determine the actual and standard distributions. The evaluation programs and techniques are developed for establishing criteria for sampling plans of reliability effectiveness, and the evaluation of system performance was based on the complex stochastic process(derived by the Runge-Kutta method. by kolmogorv's criterion and the transform of a solution to a Sturon-Liouville equation.) The special structure of this mathematical model is exploited to develop the optimal sampling plans of reliability in the complex system.

• 한국환경과학회지
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• 제21권1호
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• pp.49-55
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• 2012

In this study, the characteristic of offensive major odorous compound from the Bon-San industrial complex in Gimhae were determined by analytical methods of Gas Chromatography, High Performance Liquid Chromatography and UV/VIS Spectrophotometer. The kind of major odorous compounds examined acetaldehyde, sulfur compounds, ammonia and styrene. The concentration of all odorous compounds at 3 sampling points of industrial complex were lower than those of regulation standard levels of the industrial complex in Korea. The mean concentration of hydrogen sulfide was 0.0235 ppm at sampling point 2, it was higher than other sampling point. Complex odors was lower than regulation standard levels of the industrial complex in Korea.

• 한국컴퓨터정보학회논문지
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• 제27권6호
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• pp.139-147
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• 2022

본 연구는 신체활동수준, 주관적 건강상태, 코로나19 염려의 관계를 분석하는 것에 목적이 있다. 이를 위하여 2020년 지역사회건강조사를 바탕으로 전국 만 19세 이상 성인 229,269명의 설문데이터 자료를 분석하였다. 복합표본설계로 가중치, 층화변수, 집락변수를 지정하여 분석하였다. SPSS 통계분석 프로그램을 이용하여 복합표본 빈도분석, 복합표본 교차분석, 복합표본 회귀분석을 실시하고, 다음과 같은 결과를 얻었다. 첫째, 신체활동수준이 높은 그룹이 신체활동수준이 낮은 그룹에 비하여 주관적 건강상태가 높은 것으로 나타났다. 둘째, 신체활동수준이 높은 그룹이 신체활동수준이 낮은 그룹에 비하여 코로나19 염려가 낮은 것으로 나타났다. 셋째, 주관적 건강수준이 높은 그룹이 낮은 그룹에 비하여 코로나19 염려가 낮은 것으로 나타났다. 다만 본 연구에서는 실제 코로나19 감염여부는 분석에 포함하지 않았다는 제한점이 있다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권10호
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• pp.6121-6125
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• 2013

Background: Endometrial cancers are the most common gynecologic cancers. Endometrial sampling is a preferred procedure for diagnosis of the endometrial pathology. It is performed routinely in many clinics prior to surgery in order to exclude an endometrial malignancy. We aimed to investigate the accuracy of endometrial sampling in the diagnosis of endometrial pathologies and which findings need intra-operative frozen sections. Materials and Methods: Three hundred nine women applying to a university hospital and undergoing endometrial sampling and hysterectomy between 2010 and 2012 were included to this retrospective study. Data were retrieved from patient files and pathology archives. Results: There was 17 patients with malignancy but endometrial sampling could detect this in only 10 of them. The endometrial sampling sensitivity and specificity of detecting cancer were 58.8% and 100%, with negative and positive predictive values of 97.6%, and 100%, respectively. In 7 patients, the endometrial sampling failed to detect malignancy; 4 of these patients had a preoperative diagnosis of complex atypical endometrial hyperplasia and 2 patients had a post-menopausal endometrial polyps and 1 with simple endometrial hyperplasia. Conclusions: There is an increased risk of malignancy in post-menopausal women especially with endometrial polyps and complex atypia hyperplasia. Endometrial sampling is a good choice for the diagnosis of endometrial pathologies. However, the diagnosis should be confirmed by frozen section in patients with post-menopausal endometrial polyps and complex atypia hyperplasia.

• Journal of the Korean Statistical Society
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• 제27권4호
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• pp.459-469
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• 1998

Balanced half sample method is a simple variance estimation method for complex sampling designs. Since it is simple and flexible, it has been widely used in large scale sample surveys. However, the usual BHS method overestimate the true variance in without replacement sampling and two-stage cluster sampling. Focusing on this point , we proposed an unbiased BHS variance estimator in a stratified two-stage cluster sampling and then described an implementation method of the proposed estimator. Finally, partially BHS design is explained as a tool of reducing the number of replications of the proposed estimator.

• 산업경영시스템학회지
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• 제12권19호
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• pp.25-30
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• 1989

This study is concerned with a job sequencing method using the concept of sampling technique. This sampling technique has never been applied to develop the scheduling algorithms. The most job sequencing algorithms have been developed to determine the best or good solution under the special conditions. Thus, it is not only very difficult, but also taken too much time to develop the appropriate job schedules that satisfy the complex work conditions. The application areas of these algorithms are also very narrow. Under these circumstances it is very desirable to develop a simple job sequencing method which can produce the good solution with the short tine period under any complex work conditions. It is called a sampling job sequencing method in this study. This study is to examine the selection of the good job sequence of 1%-5% upper group by the sampling method. The result shows that there is the set of 0.5%-5% job sequence group which has to same amount of performance measure with the optimal job sequence in the case of experiment of 2/n/F/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 a little effort and time consuming. The results of ANOVA show that the two factors, number of jobs and the range of processing time are the significant factors for determining the job sequence at $\alpha$=0.01. This study is extended to 3 machines to machines job shop problems further.