A Sampling Inspection Plan with Human Error

Yong-Hwa Lee,Seung-Kweon Hong 대한인간공학회 2011 大韓人間工學會誌 Vol.30 No.5

Objective: The aim of this study is to design a sampling inspection plan with human error which is changing according to inspection time. Background: Typical sampling inspection plans have been established typically based on an assumption of the perfect inspection without human error. However, most of all inspection tasks include human errors in the process of inspection. Therefore, a sampling inspection plan should be designed with consideration of imperfect inspection. Method: A model for single sampling inspection plans were proposed for the cases that visual inspection error rate is changing according to inspection time. Additionally, a sampling inspection plan for an optimal inspection time was proposed. In order to show an applied example of the proposed model, an experiment for visual inspection task was performed and the inspection error rates were measured according to the inspection time. Results: Inspection error rates changed according to inspection time. The inspection error rate could be reflected on the single sampling inspection plans for attribute. In particular, inspection error rate in an optimal inspection time may be used for a reasonable single sampling plan in a practical view. Conclusion: Human error rate in inspection tasks should be reflected on typical single sampling inspection plans. A sampling inspection plan with consideration of human error requires more sampling number than a typical sampling plan with perfect inspection. Application: The result of this research may help to determine more practical sampling inspection plan rather than typical one.

Gy의 입자성 물질 시료채취이론에 근거한 토양 시료 채취량 결정

배범한,Bae, Bum-Han 한국지하수토양환경학회 2011 지하수토양환경 Vol.16 No.6

A bibliographical review of Gy sampling theory for particulate materials was conducted to provide readers with useful means to reduce errors in soil contamination investigation. According to the Gy theory, the errors caused by the heterogeneous nature of soil include; the fundamental error (FE) caused by physical and chemical constitutional heterogeneity, the grouping and segregation error (GE) aroused from gravitational force, long-range heterogeneous fluctuation error ($CE_2$), the periodic heterogeneity fluctuation error ($CE_3$), and the materialization error (ME) generated during physical process of sample treatment. However, the accurate estimation of $CE_2$ and $CE_3$ cannot be estimated easily and only increasing sampling locations can reduce the magnitude of the errors. In addition, incremental sampling is the only method to reduce GE while grab sampling should be avoided as it introduces uncertainty and errors to the sampling process. Correct preparation and operation of sampling tools are important factors in reducing the incremental delimitation error (DE) and extraction error (EE) which are resulted from physical processes in the sampling. Therefore, Gy sampling theory can be used efficiently in planning a strategy for soil investigations of non-volatile and non-reactive samples.

SPATIAL AND TEMPORAL INFLUENCES ON SOIL MOISTURE ESTIMATION

Kim, Gwang-seob Korea Water Resources Association 2002 Water engineering research Vol.3 No.1

The effect of diurnal cycle, intermittent visit of observation satellite, sensor installation, partial coverage of remote sensing, heterogeneity of soil properties and precipitation to the soil moisture estimation error were analyzed to present the global sampling strategy of soil moisture. Three models, the theoretical soil moisture model, WGR model proposed Waymire of at. (1984) to generate rainfall, and Turning Band Method to generate two dimensional soil porosity, active soil depth and loss coefficient field were used to construct sufficient two-dimensional soil moisture data based on different scenarios. The sampling error is dominated by sampling interval and design scheme. The effect of heterogeneity of soil properties and rainfall to sampling error is smaller than that of temporal gap and spatial gap. Selecting a small sampling interval can dramatically reduce the sampling error generated by other factors such as heterogeneity of rainfall, soil properties, topography, and climatic conditions. If the annual mean of coverage portion is about 90%, the effect of partial coverage to sampling error can be disregarded. The water retention capacity of fields is very important in the sampling error. The smaller the water retention capacity of the field (small soil porosity and thin active soil depth), the greater the sampling error. These results indicate that the sampling error is very sensitive to water retention capacity. Block random installation gets more accurate data than random installation of soil moisture gages. The Walnut Gulch soil moisture data show that the diurnal variation of soil moisture causes sampling error between 1 and 4 % in daily estimation.

2016년 국회의원선거 출구조사 오차 분석

이수빈 ( Subeen Lee ),정진우 ( Jinwoo Chung ),김영원 ( Youngwon Kim ) 한국조사연구학회 2017 조사연구 Vol.18 No.4

본 연구에서는 2016년 실시된 20대 국회의원선거 출구조사 자료를 토대로 하여 출구조사에서 발생한 오차의 발생원인을 분석하였다. 분석 결과, 새누리당과 더민주당에 대해서는 후보자 지지율을 실제보다 크게 예측하고 국민의당에 대해서는 작게 예측하는 경향이 있었다. 예측오차를 투표소추출오차와 투표소추출 외의 오차로 구분하여 보면, 새누리당의 경우에는 투표소추출에 의한 오차가 더 큰 반면에 더민주당과 국민의당의 경우에는 투표소추출 이외의 추가오차가 더 크게 발생했다. 예측오차를 당일투표자 예측오차와 사전투표자 예측오차로 구분하여 살펴본 결과 세 개의 정당 모두 당일투표자 예측오차가 더 컸다. In this study, we analyze the data of the exit poll for the 20th National Assembly election in Korea. The empirical studies show that systematical positive bias of candidates affiliated to Saenuri and Theminjoo Party occurs, whereas systematic negative bias of candidates affiliated to People21 Party occurs. The total survey error in exit poll is divided by sampling error of polling sites and the additional error which comes from non-response, early voting and second stage sampling error of voters in each sampled polling site. Our analysis show that the additional error is lower than the sampling error of Saenuri Party. In case of Theminjoo and People21 Party, the additional error is higher than the sampling error. In addition, we separate the final prediction error into the prediction error of voters on the election day and the prediction error of early voters. We notice that the prediction error of voters on election day is higher than the prediction error of early voters.

표본조사를 활용하는 사회과학연구에서 발생하는 오차에 대한 개념적 고찰

이 건 경기대학교 사회과학연구소 2014 한국사회연구 Vol.17 No.1

사람들의 생각, 태도, 개인적인 신념 등에 관한 조사는 모집단 전체를 대상으로 조사하지 않고 주로 모집단의 일부인 표본을 추출하여 조사함으로써 전체 모집단의 특성을 추정한다. 이러한 표본조사방식은 시간·비용적인 면에서 매우 효율적인 방법이라 할 수 있다. 하지만 표본을 이용한 동시에 조사는 많 은 오차를 수반한다. 그렇기에 표본조사시 발생하는 오차에 대한 관리가 조사의 품질을 결정하는 중요한 요소이다. 조사 과정에 잠재되어 있는 모든 오차를 일컬어 종합조사오차 (Total Survey Error)라고 하는데, 종합조사오차를 구성하는 오차들을 유형화 해보면 모집단의 일부만을 조사함으로써 생 기는 표본오차(sampling error), 목표모집단과 표본추출틀 (sampling frame)과의 차이로 인해 나타나는 커버리지오차 (coverage error), 표본추출을 통해 생성된 모든 조사대상자 들과 (단위 무응답자들을 제외한) 응답자들의 체계적인 응답성향의 차이로 나타나는 무응답오차(nonresponse error), 면접원, 응답자, 질문지, 사회소망성(social desirability)현상 등에서 비롯되는 측정오차(measurement error), 그리고 조사 후에 코딩 등의 오류로 인한 처리오차(processing error) 등 크게 다섯 가지로 유형화할 수 있다. 본 연구는 조사연구 전 과정에서 나타나는 오차들의 유형별 제 개념 및 이러한 오차 들이 조사결과에 어떻게 영향을 미치는지를 고찰하고 한국의 비표본오차에 대한 조사연구의 활성화를 위한 제언을 하고자 한다. Survey research is commonly used when a researcher wants to investigate people's opinions, attitudes, and beliefs in a particular area or society. A sample survey is a very efficient tool in that one can estimate population characteristics with a small number of samples. The sample survey, however, involves many potential errors, known as total survey error (TSE) in the data collection process. TSE includes sampling error which arises when a sample is used instead of the population, coverage error stemming from a mismatch between the target population and sampling frame, nonresponse error which results from systematic differences in responses between total sampled persons and respondents, measurement error due to interviewer, respondent, questionnaire, and social desirability, and processing error stemming from human errors such as coding after data collection. This study will mainly discuss what TSE means and how it negatively affects the survey data quality, and provide some suggestions for quality survey research in Korea.

연구논문 : 2012년 총선 출구조사 예측오차 분석

곽은선 ( Eun Sun Kwak ),김지연 ( Ji Yeon Kim ),김영원 ( Young Won Kim ) 한국조사연구학회 2013 조사연구 Vol.14 No.3

본 연구에서는 출구조사 예측오차의 발생 원인과 특성을 알아보기 위해 2012년에 치른 19대 총선 출구조사의 자료를 이용하여 출구조사 예측오차를 분석하였다. 예측오차를 정리해 본 결과 새누리당에 대해서는 과소 예측이, 통합야당에 대해서는 과대예측이 발생했으며, 시·도별로 편향 수준에 차이가 있었다. 예측오차를 투표소추출 오차와 실사오차로 구분해 보면 투표소추출오차에 비해 실사오차가 더 심각하였다. 또한 오차를 발생시킬 것으로 예상되는 변인들과 투표소추출오차 및 실사오차와의 상관분석을 통해 조사거절률이 실사오차에 유의한 양의 상관관계를 갖고 있으며, 표본추출률을 증가시키면 투표소추출오차가 감소한다는 사실도 확인할 수 있었다. 한편출구조사를 진행한 세 개 조사기관별로 오차를 비교해 본 결과 특히 실사오차에 있어서 조사기관간의 차이가 통계적으로 유의한 것으로 나타났다. In this study, we investigate the data of the exit poll for the 19th general election of 2012 to analyze the causes and characteristics of exit poll forecasting error. The empirical studies show that systematic negative bias of candidates affiliated to Saenuri Party is serious in the specific regions. To explore the main causes and effects of the forecasting error, the total survey error is divided by sampling error of the polling sites and non-sampling error which comes from selecting voter and collecting responses from sampled voters in each polling sites. And we consider relationships among several factors, which are anticipated as main causes of error, and non-sampling error as well as sampling error. As a result of correlation analysis, we can figure out that the nonsampling error of the exit poll mainly come from non-response. Also we consider the house effect in exit poll.

Compensation method of average current sampling error under the operating condition of low sampling‑to‑fundamental frequency ratio

Su‑In Jo,Wook‑Jin Lee 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.4

This paper describes the compensation method for average current sampling error under the operating condition of low sampling-to-fundamental frequency ratio. When the sampling-to-fundamental frequency ratio is lowered, the current ripple is very large, and an error between the sampled current and the average current during one sampling period occurs. The actual average current can be obtained from the relationship between the average voltage and current of the synchronous reference frame. The actual average voltage and reference voltage match when the inverter output voltage has no error. Thus, the proposed compensation method of average current sampling error can be implemented based on the reference voltage and sampled current. The proposed current compensation method is verified by simulations and experiments.

연구논문 : 2008 총선 출구조사의 총조사오차 분석

곽은선 ( Eun Sun Kwak ),김영원 ( Young Won Kim ) 한국조사연구학회 2010 조사연구 Vol.11 No.3

본 논문에서는 2008년 18대 총선의 출구조사 자료를 이용하여 출구조사의 정확성을 평가 할 수 있는 총조사오차 개념을 새로 정의하고, 출구조사에서 발생하는 총조사오차가 투표소추출오차와 투표자 선정 및 응답 과정에서 발생하는 실사오차 중 어떤 것에 더 많은 영향을 받는지 분석했다. 또한 선거구별 무응답률이 총조사오차와 실사오차에 미치는 영향을 분석하였고, 중앙선거관리위원회의 투표율 분석자료를 이용하여 출구조사 표본의 대표성을 검증했다. 분석 결과 선거구 내 표본 투표소 추출 관련 오차보다는 표본투표소 내에서 투표자 선택 및 응답 과정에서 발생하는 오차가 더 컸던 것으로 나타났다. 또한 무응답률과 실사오차는 양의 상관관계를 갖는 것으로 나타났으며, 이는 특정한 지지성향을 갖는 사람들의 응답 거절로 인해 표본의 대표성이 떨어지고, 결과적으로 오차가 커지는 것으로 해석될 수 있다. 아울러 선관위와 출구조사 자료에 대한 카이제곱 검정을 통해 성/연령대별 구성비에 유의한 차이가 있다는 것을 확인할 수 있었다. In this study, we newly define the Total Survey Error(TSE) in exit poll and investigate the TSEs of the exit poll survey for the 18th general election of 2008 to analyse the cause of the exit poll prediction error. To explore the main cause and effect of the total survey error, the total survey error was divided by the sampling error which comes from sampling process of poll stations and the non-sampling error which comes from selecting voter and collecting responses from sampled voters in each electoral district. We consider the relationship between non-response rates and total survey error as well as non-sampling error. Also, we study the representativeness of the exit poll sample by comparing the sex/age distribution of the exit poll data and the National Election Commission poll data.

Sampling Study on Environmental Observations : Precipitation, Soil Moisture and Land Cover Information

Yoo, Chul-Sang 한국환경과학회 1996 한국환경과학회지 Vol.5 No.2

Observational date is integral in our understanding of present climate, its natural variability and any change due to anthropogenic effects. This study incorporates a brief overview of sampling requirements using data from the first ISLSCP Field Experiment (FIFE) in 1987 which was a multidisciplinary field experiment over a 15 km grid in Konza Prairie, USA. Sampling strategies were designed for precipitation and soil moisture measurements and also detecting land cover type. It was concludes that up to 8 raingages would be needed for valuable precipitation measurements covering the whole FIFE catchment, but only one soil moisture station. Results show that as new gages or station are added to the catchment then the sampling error is reduced, but the improvement in error performance is less as the number of gages or stations increases. Sampling from remotely sensed instruments shows different results. It can be seen that the sampling error at larger resolution sizes are small due to competing error contribution from both commission and omission error.

The Effect of Transformer Leakage Inductance on the Steady State Performance of Push-pull based Converter with Continuous Current

Qian Chen,Trillion Q. Zheng,Yan Li,Tiancong Shao 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.3

As a result of the advantages such as high efficiency, continuous current and high stability margin, push-pull converter with continuous current (PPCWCC) is competitive for battery discharge regulator (BDR) which plays an important role in power conditioning unit (PCU).Leakage inductance yields current spike in low-ripple current of PPCWCCs. The operating modes are added due to leakage inductance. Therefore the steady state performance is affected, which is embodied in the spike of low-ripple current. PPCWCCs which are suitable for BDR can be separated into three types by current spike characteristics. Three representative topologies IIs1, IIcb2 and Is3 are analyzed in order to investigate the factors on the magnitude and duration of spike. Equivalent current sampling method (ECSM) which eliminates the sampling time delay and achieves excellent dynamic performance is adopted to prevent the spike disturbance on current sampling. However, ECSM reduces the sampling accuracy and telemetry accuracy due to neglecting the spike. In this paper, ECSM used in PPCWCCs is summarized. The current sampling error is analyzed in quality and quantity, which provides the foundation for offsetting and enhancing the telemetry accuracy. Finally, current sampling error rate of three topologies is compared by experiment results, which verify the theoretical analysis.