• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.3
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• pp.355-369
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• 2015

To examine species composition, abundance and biomass of fishes in the northwestern East Sea of Russian EEZ, trawl survey were conducted at 31 sampling stations from 2006 to 2008. Also, trawl survey were conducted at 21 sampling stations in the southwestern East Sea of Korean EEZ from 2006 to 2008. A total of 67 fishes were collected in the northwestern East Sea of Russian EEZ, a total of 39 fishes were collected in the southwestern East Sea of Korean EEZ. Among them, a total of 53 fishes were collected in the northwestern East Sea of Russian EEZ only, and a total of 25 fishes were collected in the southwestern East Sea of Korean EEZ only. Mean abundance per area which caught by trawl survey in the northwestern East Sea ranged from a high of $116,478inds./km^2$ in 2008 to a low of $19,737inds./km^2$ in 2006. And mean abundance per area in the southwestern East Sea ranged from a high of $89,129inds./km^2$ in 2006 to a low of $8,234inds./km^2$ in 2008. Mean biomass per area which caught by trawl survey in the northwestern East Sea ranged from a high of $11,333kg/km^2$ in 2008 to a low of $2,439kg/km^2$ in 2006. And mean biomass per area in the southwestern East Sea ranged from a high of $6,273kg/km^2$ in 2006 to a low of $1,062 kg/km^2$ in 2008. Cluster analysis, based on a Bray-Curtis similarity matrix of fourth root transformed data of number of species and individuals per area, showed division into three different groups by depth in the northwestern and southwestern East Sea.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.2 no.1
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• pp.93-104
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• 1982

DTM data evaluation regards accuracy and efficiency as its most important parameters, and these two elements are sensitively influenced by the sampling technique employed and its procedure. This study attempts to improve sampling techniques and evaluate the accuracy of DTM based on earth volume calculation, using aerial photography and field survey information as basic DTM data, and a regular grid and progressive sampling method for sampling process. Especially, the progressive sampling has employed different combinations of threshold and sampling criteria, that is, parameters influential on efficiency and accuracy, for the purpose of numerical tests intended to permit comparative analysis. The tests have resulted in the findings that in progressive sampling its grid density fits in well with given terrain characteristics in proportion to their variability. and that threshold and accuracy contain close mutual relations in which an increased threshold bringing more efficency but less accuracy. It follows, therefore. that a threshold, when appropriately determined, can be of very efficient use for considerably broad applications, and particularly, will play a significant role in its application to such general civil engineering as earth volume calculation.

• Economic and Environmental Geology
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• v.37 no.1
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• pp.49-59
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• 2004

The concectration and distribution of contaminants obtained from a contaminated land investigation or an environmental geochemistry survey constitutes the basis of a decision-making process on environmental policies or of scientific researches. As the quality of data determines the reliability of the result, the investigation plan should be adjusted according to the purpose of the investigation. In general, the effort to improve the data quality had been focused mainly on the QA/QC procedures in laboratories. The rapid progress of analytical instrument has also contributed toward improving the analytical precision to a sacrificable degree. Nevertheless, in many cases, it is not the analytical precision that needs improvement for the better precision of overall measurement process: it is rather during the sampling process in the field that is responsible for the poor precision. To assess the data quality on a measured value, ISO recommends to provide information on "measurement uncertainty" along with the measured value. The measurement uncertainty in an environmental measurement context can be explained as the statistical number that expresses the degree of the uncertainty stemming from the sampling and analytical procedures. There is a cost involved in order to improve the precision of sampling and analytical methods so as to decrease the degree of measurement uncertainty. The economical point of compromise in an investigation planning can be achieved when the allowable degree of uncertainty has been set before-hand. The investigation can then be planned accordingly not to exceed the uncertainty limit. Furthermore, if the measurement uncertainty estimated from the preliminary investigation can be separated into sampling and analytical uncertainties, it can be used as a criterion where the resources for the investigation should be allotted cost-effectively to reinforce the weakest link of the whole investigation process. This paper aims to present a method of estimating the level of measurement uncertainty of a measured contamination concentration at a site used as an example and to show how the estimated uncertainty can be applied to serve the particular purpose of an investigation.

• The Korean Journal of Applied Statistics
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• v.28 no.6
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• pp.1217-1225
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• 2015

Survey research, data is commonly collected through a sample design with complex design features that allow the relative efficiency on the precision of an estimator to be measured using the concept of the design effect compared to simple random sampling as a reference design. This concept is most useful when the design effect can be expressed as a function of various design features. We propose a design effect formula suitable under a stratified multistage sampling by generalizing Gabler et al. (1999, 2006)'s approaches for multistage sampling. Its use can either guide improvement in the design efficiency when in design stage or enable the evaluation of the adopted design features afterwards.

• The Korean Journal of Applied Statistics
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• v.30 no.6
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• pp.993-1004
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• 2017

A stratified sampling method is generally used with a sample selected using the same sample weight in each stratum in order to improve the accuracy of the sampling survey estimation. However, the weight should be adjusted to reflect the response rate if the response rate is affected by the value of the variable of interest. It may be also more effective to adjust the weights by subdividing the stratum rather than using the same weight if the variable of interest has a linear relationship with the continuous auxiliary variables. In this study, we propose a method to increase the accuracy of estimation using an informative sampling design technique when the response rate is an exponential function of the variable of interest and the variable of interest has a linear relationship with the auxiliary variable. Simulation results show the superiority of the proposed method.

• The Korean Journal of Applied Statistics
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• v.27 no.2
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• pp.239-247
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• 2014

For a sensitive survey in which the population is composed by several strata with quantitative attributes, we present an additive stratified quantitative attribute randomized response model which applied stratified random sampling instead of simple random sampling to the models of Himmelfarb-Edgell's additive quantitative attribute model and Gjestvang-Singh's. We also establish theoretical grounds to estimate the stratum mean of sensitive quantitative attributes as well as the over all mean. We deal with the proportional and optimal allocation problems in each suggested model and compare the relative efficiency of the suggested two models; subsequently, Himmelfarb-Edgell's model is more efficient than Gjestvang-Singh's model under the condition of stratified random sampling.

• School Mathematics
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• v.8 no.4
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• pp.441-463
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• 2006

The purpose of this research is to investigate how elementary school students execute sampling with what designs in order to gather information under a situation that requires collecting data and information about their household and everyday life, and to examine how they use tools, including table or graph, etc., in order to perform efficient analysis of data and information they surveyed, also what results they acquire. To test this, the researcher set up a situation in advance that requires collecting data, and, under this circumstance, the researcher instructed and guided school students to look for methods how to design and survey in order to gather data by having them discuss tasks, involving small groups or entire class, and seek its solutions by themselves through trial and errors. The results from surveys revealed that a lesson, which will have students do sampling and arrange statistical data and analyze the results, was possible to carry out in the class of 6th grade of elementary school.

• The Research Journal of the Costume Culture
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• v.17 no.6
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• pp.1141-1154
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• 2009

As a preliminary research of body characteristics analysis of Korean obese woman, this study aims to select optimal obesity judgment tools for reliable sampling of obese subjects from 2,425 female measurement data out of 2004 Size Korea project's raw data. From previous researches related to obesity, 7 obesity judgment tools were chosen. 2007 obesity rate(26.3%) of Korean female adults was refered in selecting optimal obesity judgment criteria in the study. The results are as follows. Firstly, it was verified that BMI was the most suitable in judging and sampling the obese subjects by the percentile analysis. R$\ddot{o}$hrer index was also reliable in grouping the obese subjects from a population. Secondly, it was concluded that the obesity ratios of relative weight 120 and higher group, R$\ddot{o}$hrer index 1.6 and higher group and waist girth 80cm and higher group were the most similar to obesity rate of Korean female adults by 2007 National Health & Nutrition Survey. Thirdly, 30 direct measurements, age, 2 drop values and 6 ratios of 7 groups by the obesity judgment tools showed the significance each other at p<0.001 level. On the other hand, "bust point to bust point" and "waist to hip length" measurements didn't show the significant differences among 7 groups. Conclusively, 4 to 5 satisfactions out of 7 obesity judgment criteria were adequate and sufficient in sampling the obese subjects. If it is needed the strict criteria for judging the obesity, 5 satisfactions and higher group will be the best choice as the obese subjects. However 4 satisfactions and higher group generally, will be adequate for sampling of the obese subjects.

• The Korean Journal of Applied Statistics
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• v.26 no.2
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• pp.209-222
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• 2013

We apply stratified cluster sampling to a replicated systematic unrelated question model for a large scale survey in which the population is comprised of several strata developed by several clusters and with sensitive parameters. We first present a replicated systematic unrelated question model using an unrelated question model to procure sensitive information from the population of clusters and then develop a suggested model to an unrelated question by a stratified cluster replicated systematic sampling that can be used in large population of strata. We cover the proportional and optimum allocation for the suggested model. Finally, we compare and analyze the efficiency of the suggested model with the replicated systematic unrelated question model.

• Journal of the Korea Computer Industry Society
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• v.4 no.4
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• pp.455-466
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• 2003

A self-selected web survey was utilised to Investigate the preference of online holiday travellers to the Internet functions applied to the extensive decision-making process by adoptingthe Canberra tourism website as a case study in Australia. The use of web-based surveys is not at a mature stage, compared to other traditional surveys such as mail survey and telephone survey that have already-known home addresses and phone numbers as a frame population. The adopted web survey relies on non-probability sampling without a known frame population thatcan cause serious research errors. Therefore, the results of this study need to be compared to other official published statistics in order toverify reliability or credibility of the self-selected web survey. This study discusses the extent to which the self-selected web survey can be validated by finding the significant difference not only between the demographic results of web survey and those of official statistics released by several articles including the Graphic, Visualizations and Usability Center (GVU) at Georgia Tech research but also between the travel background features and those of ‘ACT Tourism Masterplan 2001-2005’published by the Canberra Tourism ＆ Event Corporation (CTEC) located in Australian Capital Territory (ACT).