• 제목/요약/키워드: Sampling efficiency

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A Modified Single Sampling Plan for the Inspection of Attribute Quality Characteristics

  • Subramani, J.;Balamurali, S.
    • Industrial Engineering and Management Systems
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    • 제15권1호
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    • pp.41-48
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    • 2016
  • In this manuscript, a modified single sampling plan is proposed for the inspection of products in which the nonconforming items can be classified in to two categories namely critical and non-critical; and explained with the help of industrial example. The operating procedure of this plan is also proposed and the performance measures such as the probability of acceptance, average sample number, average total inspection and average out going quality are also derived. The optimal parameters are determined which will have minimum sample size. The efficiency of the proposed plan is also discussed over the conventional single sampling plan. The extensive tables for selecting a modified single sampling plan based on AQL and LQL are provided for both Binomial and Poisson distributions and explained with the help of industrial data.

Adaptive kernel method for evaluating structural system reliability

  • Wang, G.S.;Ang, A.H.S.;Lee, J.C.
    • 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.

배지 종류 및 저장 조건에 따른 impactor의 부유세균 시료 채취 효율 평가 (Evaluation of Impactor's Collection Efficiency on Airborne Bacteria by Type of Agar Media and Storage Condition)

  • 김기연;장규엽;박재범;김치년;이경종
    • 한국환경보건학회지
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    • 제33권2호
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    • pp.145-149
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    • 2007
  • The range of reduction rates of airborne bacteria concentration at 6 hrs, 12 hrs, 24 hrs and 48 hrs, which means a storage time until input of agar media into incubator after air sampling with an impactor. were 15-20%, 25-40%, 35-50% and 55-70%, respectively, compared to initial concentration. Types of agar media and storage thermal condition did not significantly affect a collection efficiency of impactor in terms of evaluating airborne bacteria level (p>0.05). To better improve the impactor's collection efficiency of airborne bacteria, based on the result of this study, it is recommended that the vicinity of $25^{\circ}C$ should be sustained until input of agar media into incubator after air sampling.

ESM을 통해 본 대학생의 주관적 삶의 질 -정서, 인지적 효율성, 만족도의 측면에서- (Korean University Students' Emotion, Cognitive Efficiency and Satisfaction through the Experiential Sampling Method)

  • 김기옥;김순옥;황선진;이수진;현은자;최인수;유현정
    • 대한가정학회지
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    • 제43권2호
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    • pp.203-229
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    • 2005
  • The purpose of this study was to explore the perceived quality of life of Korean university students'. The perceived quality of life was composed of three dimensions: emotion, cognitive efficiency, and satisfaction. The study results were as follow: 1. Korean university students felt more positive emotions when they spent time for social activities. 2. In the cognitive efficiency, social activities also scored highly of 5 questions, but in the item of "awareness of another person's eye", productive activities were higher. 3. Korean university students were more satisfied with themselves when they spent time for productive activities. However, they were more satisfied with their work itself when the work was social activities. 4. Korean university students' emotions, cognitive efficiencies, and satisfaction were significantly different by socio-graphic variables and context.

2행정 디젤기관의 소기 효율 평가에 관한 연구 (A Study on the Evaluation of Scavenging Efficiency in a Two-Stroke Diesel Engine.)

  • 조규백;강건용;이진욱;정용일
    • 연구논문집
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    • 통권28호
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    • pp.49-58
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    • 1998
  • 포핏밸브형 2행정 기관의 소기 시스템 형상 변화에 따른 소기유동 및 소기효율의 개선 효과를 해석하기 위해, 각 흡기포트 형상별 소기 유동 가시화와 소기효율 정량화 연구를 수행하고자 한다. 소기시스템의 형상은 기계연구원에서 독자 개발한 RSSV(Rotatable Shrouded Scavenging Valve)의 슈라우드 각도를 변화시켰으며, 소기 효율 정량화를 위해 정상상태하에서 등유와 착색된 물을 사용한 single-cycle method. 동적모사장치(dynamic simulatior)에서 $CO_2$$O_2$가스를 사용한 가스추출법(gas sampling method)을 적용하였으며 실제 기관에서의 소기 효율을 측정하기 위해 압력 선도를 해석하였다. 위 실험들의 결과로부터 $90^circ$슈라우드 밸브가 가장 높은 효율을 가지는 것으로 판명되었으며, 특히 이들 실험방법들은 2행정 엔진 개발에 있어 시간과 비용을 절감하는데 아주 유용한 기법임을 알 수 있었다.

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A PROPOSAL ON ALTERNATIVE SAMPLING-BASED MODELING METHOD OF SPHERICAL PARTICLES IN STOCHASTIC MEDIA FOR MONTE CARLO SIMULATION

  • KIM, SONG HYUN;LEE, JAE YONG;KIM, DO HYUN;KIM, JONG KYUNG;NOH, JAE MAN
    • Nuclear Engineering and Technology
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    • 제47권5호
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    • pp.546-558
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    • 2015
  • Chord length sampling method in Monte Carlo simulations is a method used to model spherical particles with random sampling technique in a stochastic media. It has received attention due to the high calculation efficiency as well as user convenience; however, a technical issue regarding boundary effect has been noted. In this study, after analyzing the distribution characteristics of spherical particles using an explicit method, an alternative chord length sampling method is proposed. In addition, for modeling in finite media, a correction method of the boundary effect is proposed. Using the proposed method, sample probability distributions and relative errors were estimated and compared with those calculated by the explicit method. The results show that the reconstruction ability and modeling accuracy of the particle probability distribution with the proposed method were considerably high. Also, from the local packing fraction results, the proposed method can successfully solve the boundary effect problem. It is expected that the proposed method can contribute to the increasing of the modeling accuracy in stochastic media.

적응집락추출에서 표본크기 결정과 추정량의 효율 비교 (Determination of Sample Size and Comparison of Efficiency in Adaptive Cluster Sampling)

  • 낭궁평;원혜경;최재혁
    • 응용통계연구
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    • 제20권3호
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    • pp.605-618
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    • 2007
  • 모집단 단위들이 희박하게 존재하고 접근하기 어려운 경우에 적용하는 적응추출설계에서의 추출과정은 관심변수의 관측값에 의존한다. 동일한 표본크기에서 적응집락추출의 추정량은 단순임의추출의 추정량에 비해 효율이 더 좋다 적응추출에서 Rao-blackwell의 정리를 적용하여 Murthy의 추정량의 형태로 수정한 한센-휴비_(HH) 추정량과 호르비_-톰슨 (HT) 추정량은 기존의 추정량에 비해 작은 분산을 가진다. 본 연구는 초기표본을 바꿔가면서 기대표본크기와 적응추출의 표본크기 하의 단순임의추출의 추정량과 적응추출의 추정량의 효율을 비교하였다.

Filter- and Denuder-Based Organic Carbon Correction for Positive Sampling Artifacts

  • Hwang, InJo;Na, Kwangsam
    • Asian Journal of Atmospheric Environment
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    • 제11권2호
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    • pp.107-113
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    • 2017
  • This study describes (1) the impact of positive sampling artifacts caused by not only a filter-based sampling, but also a denuder-based sampling in the determination of particle-phase organic carbon (POC), (2) the effect of sample flow rate on positive artifacts, and (3) an optimum flow rate that provides a minimized negative sampling artifact for the denuder-based sampling method. To achieve the goals of this study, four different sampling media combinations were employed: (1) Quartz filter-alone (Q-alone), (2) quartz filter behind quartz-fiber filter (QBQ), (3) quartz filter and quartz filter behind Teflon filter (Q-QBT), and (4) quartz filter behind carbon-based denuder (Denuder-Q). The measurement of ambient POC was carried out in an urban area. In addition, to determine gas-phase OC (GOC) removal efficiency of the denuder, a Teflon filter and a quartz filter were deployed upstream and downstream of the denuder, respectively with varying sample flow rates: 5, 10, 20, and 30 LPM. It was found that Q-alone sampling configuration showed a higher POC than QBQ, Q-QBT, and Denuder-Q by 12%, 28%, and 23%, respectively at a sample flow rate of 20 LPM due to no correction for positive artifact caused by adsorption of GOC onto the filter. A lower quantity of GOC was collected from the backup quartz filter on QBQ than that from Q-QBT. This was because GOC was not in equilibrium with that adsorbed on the front quartz filter of QBQ during the sampling period. It is observed that the loss of particle number and mass across the denuder increases with decreasing sample flow rate. The contribution o f positive arti facts to POC decreased with increasing sample flow rate, showing 29%, 25%, and 22% for 10, 20, and 30 LPM, respectively. The 20 LPM turns out to be the optimum sample flow rate for both filter and denuder-based POC sampling.

층화추출과 계통추출을 이용한 효율적인 보조정보 사용 (Efficient Use of Auxiliary Information through the Stratified Sampling and Systematic Sampling Design)

  • 김관수;박민규
    • 한국조사연구학회지:조사연구
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    • 제10권1호
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    • pp.155-168
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    • 2009
  • 표본설계 단계에서 이용 가능한 보조정보가 있는 경우 효율적인 표본추출방법으로 층화추출법이 흔히 고려된다. 특별히 층화변수로 이용할 수 있는 변수가 많은 경우 전체 층의 숫자가 커지게 되며, 이때 각 층으로부터 한 단위를 추출하는 층 표본크기가 1인 층화추출이 효율적임이 알려져 있다. 그러나 각 층으로부터 하나의 추출단위를 추출하는 층 표본크기가 1인 층화추출의 경우 불편 분산 추정량의 계산이 불가능하다. 불편 분산 추정량의 계산은 층의 수를 줄이고 각 층으로부터 두 개의 표본추출단위를 표집하는 층 표본크기가 2인 층화추출에서 가능하나 중요 층화변수가 누락될 경우 층 표본크기가 1인 층화추출에 비해 그 효율성이 떨어진다. 본 연구에서는 Park & Fuller(2008)에 의해 제시된 층 표본크기가 2인 균형 층화추출과 호르비츠-톰슨 추정량의 불편 분산 추정량을 살펴보고, 모의실험을 통하여 여러 가지 층화추출법과 계통추출법을 비교한다. 또한 제시된 표본추출법을 2006년 청년패널 자료에 적용하여 그 효율성을 평가한다.

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A Hybrid Algorithm for Online Location Update using Feature Point Detection for Portable Devices

  • Kim, Jibum;Kim, Inbin;Kwon, Namgu;Park, Heemin;Chae, Jinseok
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제9권2호
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    • pp.600-619
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    • 2015
  • We propose a cost-efficient hybrid algorithm for online location updates that efficiently combines feature point detection with the online trajectory-based sampling algorithm. Our algorithm is designed to minimize the average trajectory error with the minimal number of sample points. The algorithm is composed of 3 steps. First, we choose corner points from the map as sample points because they will most likely cause fewer trajectory errors. By employing the online trajectory sampling algorithm as the second step, our algorithm detects several missing and important sample points to prevent unwanted trajectory errors. The final step improves cost efficiency by eliminating redundant sample points on straight paths. We evaluate the proposed algorithm with real GPS trajectory data for various bus routes and compare our algorithm with the existing one. Simulation results show that our algorithm decreases the average trajectory error 28% compared to the existing one. In terms of cost efficiency, simulation results show that our algorithm is 29% more cost efficient than the existing one with real GPS trajectory data.