• 산업경영시스템학회지
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• 제14권24호
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• pp.1-5
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• 1991

Various linear cost models have been proposed that can be used to determine a sampling plan by attributes. This paper is concerned with this sampling cost model when the probability that the number of nonconforming item is smaller than the break-even quality level is known. In addition to this situation, a constraint by AOQL is considered. Under these conditions, optimal sampling plan which minimize the average cost per lot is suggested.

• 산업경영시스템학회지
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• 제11권18호
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• pp.59-69
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• 1988

This study represents the method of application of W.S(Work Sampling) to determine job sequence. The result shows job sequence which has the came performance measure of optimal job sequence is selected by average number of 199 sampling. In the case, the optimal job sequence is not selected within the sampling number of 921 which satisfy the reliability of 99.5% and precision of 99%, the deviation is very little which 0.73%. This improves the possibility of application of W.S method to select optimal job sequence is very high.

• 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.

• 방송공학회논문지
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• 제21권5호
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• pp.803-815
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• 2016

이 논문에서는 GNSS(global navigation satellite system) 신호를 RF(radio frequency) 대역에서 표본화하여 디지털 영역에서 복조하는 직접 RF 표본화 수신기를 설계하고 그 성능을 살펴보고자 한다. 직접 RF 표본화 방식은 IF(intermediate frequency) 대역에서 AD(analog to digital) 변환을 하고 복조하는 기존의 IF 변환 방식과 다르게, 아날로그 믹서(mixer)를 전혀 사용하지 않고 안테나 출력인 통과대역 신호를 직접 AD 변환하여 이후의 수신기의 모든 과정을 디지털 영역에서 처리하는 기술이다. IF 변환 방식과 비교하면 하드웨어 구조가 덜 복잡하고 전송환경 변화에 따른 재구성이 가능하며 하나의 AD 변환기를 사용하여 여러 대역의 신호를 동시에 변환할 수 있다는 장점이 있다. 이와 같은 재구성 기능과 동시 수신 기능은 특정 대역의 신호가 적으로부터 전파방해를 받았을 때 후속시스템으로의 빠른 전환이 필요한 군용 시스템에서 매우 중요한 역할을 한다. 한편 여러 대역의 신호를 한 번에 AD 변환하려면 수신하고자 하는 신호의 반송파 주파수, 대역폭, 표본화 후의 중간주파수 그리고 보호 대역 등을 고려하여 표본화 주파수를 정하는 것이 중요하다. 이 논문에서는 GPS L1, GLONASS G1 및 G2 등의 GNSS 신호를 동시에 수신할 수 있는 표본화 주파수를 선택하고 이를 적용한 직접 RF 표본화 수신기를 설계한다. 또한 설계한 수신기를 상용 AD 변환기와 소프트웨어를 사용하여 구현한 후 실제 신호의 수신시험을 통해 수신 성능을 살펴본다.

• 조명전기설비학회논문지
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• 제22권1호
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• pp.104-112
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• 2008

본 논문은 변전소 신뢰도 평가를 위하여 개발한 컴퓨터 프로그램을 소개하고 있다. 개발한 프로그램은 시스템상태천이 샘플링(system state transition sampling)을 이용한 몬테카를로 법을 관간으로 하고 있다. 시스템상태천이 샘플링은 평가 결과를 신속히 얻을 수 있지만, 평가 대상이 지수분포(exponential distribution)로 모형화된 경우에만 적용할 수 있다는 단점이 있다. 본 프로그램에서는 정전을 유발하는 사건간의 배타성을 가정함으로써 고장 수리시간의 모형으로 비지수분포를 사용할 수 있도록 하였다. 개발한 프로그램을 신뢰도 평가결과가 잘 알려진 시스템에 적용하여 개발한 프로그램의 신뢰성을 증명하였다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2005년도 춘계공동학술대회 발표논문
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• pp.723-729
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• 2005

Traditional statistical process control(SPC) applied to discrete part industry in the form of control charts can look for and eliminate assignable causes by process monitoring. On the other hand, engineering process control(EPC) applied to the process industry in the form of feedback control can maintain the process output on the target by continual adjustment of input variable. This study presents controlling and monitoring rules adopted variable sampling interval(VSI) to change sampling intervals in a predetermined fashion on the predicted process levels for integrated EPC and SPC systems. Twelve rules classified by EPC schemes(MMSE, constrained PI, bounded or deadband adjustment policy) and type of sampling interval combined with EWMA chart of SPC are proposed under IMA(1,1) disturbance model and zero-order (responsive) dynamic system. The properties of twelve control rules under three patterns of process change(sudden shift, drift and random shift) are evaluated and discussed through simulation and control rules for integrated VSI EPC and SPC systems are recommended.

• 한국위성정보통신학회논문지
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• 제8권4호
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• pp.130-134
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• 2013

본 논문에서는 3D 방송의 기본적인 원리를 설명하고 3D 방송을 CS 기술을 적용하여 데이터 용량을 줄이는 방식을 제안한다. 샘플링 이론과 CS 기술의 차이점을 설명하고 개념과 동작원리를 설명한다. 최근 제안된 CS 센싱의 복원 알고리즘인 AMP(Approximate Message Passing)와 CoSaMP(Compressive Sampling Matched Pursuit)를 소개하고 이를 이용하여 이미지 데이터를 압축 복원하여 비교한다. 두 알고리즘의 계산시간을 비교하여 낮은 복잡도를 갖는 알고리즘을 판단한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
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• pp.1235-1238
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• 1987

In this paper, a new focusing method, to be called the sampled delay focusing (SDF), is proposed. This method improves the lateral resolution in ultrasound imaging system. In SDF, the analog delay lines are no longer necessary because sampling sum process can replace the conventional delay sum process. Also, this method offers continuous dynamic focusing on the resolution pixel basis if the maximum delay time is less than the sampling interval. Second order sampling is adopted in order to extend the sampling interval.

• 상하수도학회지
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• 제27권2호
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• pp.233-239
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• 2013

Sampling rate of Hydraulic pressure data, depending on the intended use of the water distribution system is an important factor. If sampling interval of hydraulic data is short, that will be more useful but it demand a lot of expense for maintenance. In this study, based on simulation of water distribution system 2 khz data, statistical techniques of student t distribution, non-exceedance probability using the optimal sampling rate for research.

• Structural Engineering and Mechanics
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• 제5권2호
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• pp.115-126
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• 1997

Importance sampling methods have been developed with the aim of reducing the computational costs inherent in Monte Carlo methods. This study proposes a new algorithm called the adaptive kernel method which combines and modifies some of the concepts from adaptive sampling and the simple kernel method to evaluate the structural reliability of time variant problems. The essence of the resulting algorithm is to select an appropriate starting point from which the importance sampling density can be generated efficiently. Numerical results show that the method is unbiased and substantially increases the efficiency over other methods.