• 대한산업공학회지
• /
• 제28권4호
• /
• pp.368-378
• /
• 2002

As more companies are equipped with data aquisition systems for their products, huge amount of field warranty data has been accumulated. We focus on the case when the field data for a given product comprise with the number of sales and the number of the first failures for each period. The number of censored items and their ages are assumed to be given. This type of data are incomplete in the sense that the age of a failed item is unknown. We construct a model for this type of data and propose an algorithm for nonparametric maximum likelihood estimation of the product reliability. Unlike the nonhomogeneous Poisson process(NHPP) model, our method can handle the data with censored items as well as those with small population. A few examples are investigated to characterize our model, and a real field warranty data set is analyzed by the method.

• Journal of Preventive Medicine and Public Health
• /
• 제42권2호
• /
• pp.130-134
• /
• 2009

Objectives : A method of estimation using 8 populationbased cancer registries databases in Korea(KRCR DB) has been introduced as another strategy for validly estimating the national cancer incidence(NCI) in Korea. The purpose of this study was to evaluate the validity of this method with using the 7 KRCR DBs, excluding Seoul covering 21% of the total population of Korea. Methods : We designed the study method(NCSE_7) as same as the estimating method with using 8 KRCR DBs (NCSE_8) in order to ensure maximal comparability. We defined the expected number of cancer cases in each registry as the number of observed cases and then we added the weighted observed cases according to gender, age and the proportion of the population covered by each registry for the population of the seven regions and the population of all areas, with excluding these seven regions. From the expected number of total cancer incidents, the estimated NCI was calculated by dividing the expected number of cancer cases by the number of the total population. The standard error(SE) of the estimated incidence was also taken from the expected number of total cancer incidents. Results : Compared with the results of the NCSE_8, the overall age-standardized rates(ASR) in men and women became over-estimated and under-estimated, respectively. Primary sites that showed statistically significant differences were the colo-rectum, prostate, breast and thyroid. The index of death certificate only(DCO)and microscopically verified(MV)% indicating levels of data quality were decreased, especially for the brain in DCO% and kidney in the MV%. Conclusions : The database of Seoul regional cancer registry has a key role for the method to estimate the valid nationwide cancer statistics in Korea with using the population-based cancer registries databases.

• Journal of the Korean Data and Information Science Society
• /
• 제17권3호
• /
• pp.851-859
• /
• 2006

The family income distributions of NLSY97 and CPS youth data are compared by using the generalized beta distribution of the second kind. The null hypothesis that the two data sets represent the same underlying population is rejected. The ML estimation suggests that NLSY97 data are oversampled in an income group of $11,308 or less, by about 15.7% compared to CPS data.

• 한국데이터정보과학회:학술대회논문집
• /
• 한국데이터정보과학회 2001년도 추계학술대회
• /
• pp.17-24
• /
• 2001

A method is proposed for efficiently estimating the mean of a population which has a linear trend. The proposed estimator is based on the centered modified systematic sampling method and the concept or interpolation. Using the expected mean square error criterion, it is shown that the proposed method is more efficient than conventional methods in most real cases.

• Communications for Statistical Applications and Methods
• /
• 제16권5호
• /
• pp.763-779
• /
• 2009

노래 연습장에서 연주되는 노래곡목별 히팅수를 정확하게 추정하기 위한 표본설계에서는 조사모집단 정의와 층화방안을 연구하고 기존데이터를 분석하여 표본크기를 산출한 후에 표본배분방법을 연구하였다. 표본설계에 의해서 선정된 표본업소들의 대표성을 온라인 노래연습장의 로그데이터를 이용하여 모수추정치의 오차를 분석하여 검토하였다. 오프라인 노래 연습장의 모수추정법을 제안하고 실제로 수집한 로그데이터로부터 모수추정치를 계산하여 온라인과 오프라인 노래연습장에서 연주되는 노래곡목별 히팅수에서 많이 차이가 있음을 보였다. 온라인과 오프라인 노래연습장의 특성차이를 반영한 분배방법의 개선안을 제안하고 비교분석을 통해서 최적 분배방법을 선정하였다.

• 한국방재안전학회논문집
• /
• 제14권4호
• /
• pp.61-67
• /
• 2021

본 연구에서는 도시 설계의 핵심 요소인 상수도 공급량의 적정성에 대해 살펴보았다. 상수도의 공급은 설계가 진행됨에 따라 다양한 방식으로 분석된다. 기초 자료 수집 분석을 시작으로 수급 계획을 수립하여 상수도 공급량을 산정하는데 본 연구에서는 인구추정과 원단위 산정의 적정성에 대하여 평가하였다. 실측자료를 확보할 수 있는 제 2기 신도시 중 위례신도시를 연구대상지역으로 선정하였다. 관련 자료를 분석하여 장래인구와 원단위를 확인하고 실측자료와 비교하였다. 위례신도시의 2020년 9월 기준 인구는 93,977명으로 계획인구 110,990명으로 약 84%의 적정성을 보임에 따라 계획인구와 실제 인구가 거의 유사하게 나타나는 것을 확인할 수 있었다. 원단위의 경우 설계 당시 서울지역 314ℓ/인, 성남지역의 320ℓ/인으로 산정되었다. 분석 결과, 계획도시 내의 공급량을 알아보면서 인구추정에 있어 어느 정도 일치함을 알 수 있었으나 현재 우리나라의 경우는 지속적인 개발에서 벗어나 기존의 도시 활성화에 대한 관심이 많은바, 구도심에 대한 공급량의 적정성에 관해서도 추후 연구가 필요가 있는 것으로 판단된다.

• 한국시스템다이내믹스연구
• /
• 제13권2호
• /
• pp.47-71
• /
• 2012

The purpose of this research is the examination of validity of data as well as simulation model, i.e. to simulate the real data in the SD model with the least error using the adjustments for the faithful reflection of real data to the simulation. In general, SD programs (e.g. VENSIM) utilize the Euler or Runge-Kutta method as an algorithm. It is possible to reflect the trend of real data via these two estimation methods however can cause the validity problem in case of the simulation requiring the accuracy as they have endogenous errors. In this article, the future population estimated by the Korea National Statistical Office (KNSO) to 2050 is simulated by the aging chain model, dividing the population into three cohorts, 0-14, 15-64, 65 and over cohorts by age and offering the adjustments to them. Adjustments are calculated by optimization with three different methods, optimization in EXCEL, manual optimization with iterative calculation, and optimization in VENSIM DSS, the results are compared, and at last the optimal adjustment set with the least error are found among them. The simulation results with the pre-determined optimal adjustment set are validated by methods proposed by Barlas (1996) and other alternative methods. It is concluded that the result of simulation model in this research has no significant difference from the real data and reflects the real trend faithfully.

• Communications for Statistical Applications and Methods
• /
• 제6권3호
• /
• pp.755-760
• /
• 1999

In multivariate stratified sampling surveys it is general to use a few stratification variables which are highly correlated with the important variables at design stage. But there might be some secondary study variables which are not so highly correlated with those stratification variables. In that case it is not efficient to use the same type of estimator due to the secondary variables as the one base on the important variables. A post-stratified estimation is proposed to increase the efficiency of the estimator with existence of secondary variables. The proposed method is illustrated with a set of fishery household population survey data.

• Animal Bioscience
• /
• 제37권5호
• /
• pp.795-806
• /
• 2024

Objective: Karan Fries (KF), a high-producing composite cattle was developed through crossing indicine Tharparkar cows with taurine bulls (Holstein Friesian, Brown Swiss, and Jersey), to increase the milk yield across India. This composite cattle population must maintain sufficient genetic diversity for long-term development and breed improvement in the coming years. The level of linkage disequilibrium (LD) measures the influence of population genetic forces on the genomic structure and provides insights into the evolutionary history of populations, while the decay of LD is important in understanding the limits of genome-wide association studies for a population. Effective population size (N_e) which is genomically based on LD accumulated over the course of previous generations, is a valuable tool for e valuation of the genetic diversity and level of inbreeding. The present study was undertaken to understand KF population dynamics through the estimation of N_e and LD for the long-term sustainability of these breeds. Methods: The present study included 96 KF samples genotyped using Illumina HDBovine array to estimate the effective population and examine the LD pattern. The genotype data were also obtained for other crossbreds (Santa Gertrudis, Brangus, and Beefmaster) and Holstein Friesian cattle for comparison purposes. Results: The average LD between single nucleotide polymorphisms (SNPs) was r² = 0.13 in the present study. LD decay (r² = 0.2) was observed at 40 kb inter-marker distance, indicating a panel with 62,765 SNPs was sufficient for genomic breeding value estimation in KF cattle. The pedigree-based N_e of KF was determined to be 78, while the N_e estimates obtained using LD-based methods were 52 (SNeP) and 219 (genetic optimization for N_e estimation), respectively. Conclusion: KF cattle have an N_e exceeding the FAO's minimum recommended level of 50, which was desirable. The study also revealed significant population dynamics of KF cattle and increased our understanding of devising suitable breeding strategies for long-term sustainable development.

• 한국통신학회논문지
• /
• 제25권6B호
• /
• pp.1120-1126
• /
• 2000

Recently, in order to analyze the time series problems that occur in the nature word, and analyzing method using a neural electric network is being studied more than a typical statistical analysis method. A neural electric network has a generalization performance that is possible to estimate and analyze about non-learning data through the learning of a population. In this paper, after collecting weather datum that was collected from 1987 to 1996 and learning a population established, it suggests the weather forecasting system for an estimation and analysis the future weather. The suggested weather forecasting system uses 28*30*1 neural network structure, raises the total learning numbers and accuracy letting the selecting concentration learning about the pattern, that is not collected, using the descending epsilon learning method. Also, the weather forecasting system, that is suggested through a comparative experiment of the typical time series analysis method shows more superior than the existing statistical analysis method in the part of future estimation capacity.