Earticle

In quantitative studies, a randomsample is supposed to be randomly selected by probability sampling in sucha way that it represents a population. The statistical analysis of corpus frequencydata is based on a random sample model, which assumes that the corpus wasrandomly selected from the language. However, Kilgarriff (2005), Evert (2006),Goh (2011) show that typical corpus data severely violate the randomnessassumption. This paper aims to evaluate random sampling methods for corpuslinguistics and to explore their characteristics and applicability. They are evaluatedon the relative frequencies of 30 morphemes and the frequencies of all morphemetypes which occur in each sample observed from 1,000 resampling trials basedon how close each random sample is to the normal distribution and theZipf-Mandelbrot (Mandelbrot 1977) law. The present study creates three findings. First, systematic sampling at the unit of measurement, i.e. individual words froman entire corpus is a best way to construct random samples for corpus linguistics. Second, the closer the relative frequencies of 30 morphemes in a sample lieto the normal distribution, the closer the frequency distribution of all morphemetypes to the Zipf-Mandelbrot distribution. Third, It is an effective way to utilizerandom samples for solving problems that stem from different sample size anddata sparseness. Moreover, using them facilitates detecting rather big differencein word frequencies obtained from different corpora.

Purpose: To compare patient care multipliers estimated from subjective evaluation against work sampling (WS) techniques in genetic nursing activities. Methods: An observational WS technique was conducted from November to December 2019 with nine genetic nurses in a tertiary referral center in Malaysia. The WS activity instrument was devised, validated, and pilot tested. All care- and non-care-related activities were sampled at 10-minute intervals within 8 hours of working over 14 days, followed by a subjective evaluation of activities survey over the same period. Bonferroni correction was undertaken for multiple testing with a p value of 0.0025. Results: The two techniques produced significant differences in genetic nurses’ activities categorization. The WS showed that compared with subjective evaluation, direct care (19.3% vs. 45.0%; p < .001) was estimated to be significantly lower, and indirect care (40.4% vs. 25.6%; p < .001) and unit-related activity (28.5% vs. 16.9%; p < .001) were higher. Both techniques produced a similar proportion of time spent in other non-care activities (12.0%) but differed in genetic meetings and information-gathering activities. While the multipliers for patient face-to-face contact were significantly larger between WS (4.57) and the survey (1.94), the multipliers for patient care time were smaller between WS (1.47) and the survey (1.24), indicating that caution should be taken when multiplying for patient contact time compared to patient care activity to determine the cost of care provision. Conclusion: A considerable proportion of time spent away from the patient needs to be allocated to patient-related care time. Thus, estimating the paid cost solely based on direct time with patients considerably underestimates the cost per hour of nurses' care. It is recommended to employ ‘patientrelated activity’ instead of the ‘face-to-face contact’ multiplier because the former did not significantly differ from the one estimated using WS.

The successful launch of Arirang satellites allow the acquisition of high resolution satellite imagery of Korean territory and enables the transition from the conventional cultivation area survey method to new image based methods adopted in advanced nations. In this study, we suggested reasonable sizes of the primary sampling unit and the secondary sampling unit for the satellite imagery based sampling design in 8 provinces preselected for this research. The PSU size was determined mainly in consideration of intracorrelation that shows the degree of homogeneity within each cluster and the efficiency of the image process. For the SSU size, we considered the relative standard error and the differences between the land cover maps produced by the Ministry of Environment and the satellite imagery processed by the National Statistical Office.

일반적으로 실내 공기질을 조절하기 위해서는 환기의 역할이 중요하다. 최근 코로나-19 등 감염병의 확산으로 거주자들의 실내에서 보내는 시간이 늘어남에 따라 환기의 중요성은 더욱 높아지고 있으며, 환기성능에 대한 관심도 더욱 높아지는 추세이다. 많은 국가에서 현재 환기 성능을 파악하는 지표로서 시간당 환기횟수를 사용하고 있으며, 국내에서도 공동주택을 대상으로 시간당 0.5회 이상의 환기횟수를 확보하도록 규제하고 있다. 하지만, 선행연구 및 국내외 환기성능 평가 관련 표준을 검토한 결과 시간당 환기횟수만을 통해 실내 환기 성능을 평가하는데에는 실질적 실내 환기 성능을 평가하는 데에는 한계가 있는 것으로 나타났으며, 실질적인 환기 성능을 평가하기 위해서는 실내 국소부위를 대상으로 오염물질 저감속도와 공간내 환기 성능 균일도 등을 고려하는 것이 필요할 것이다. 이에 대해 본 연구에서는 추적가스 희석법을 이용한 실증 실험을 통해 측정 위치별 유속, 공기연령 및 환기효율을 측정하고 비교하였으며, 측정점별 조합에 따른 평균값과 공간 내 중심점에서의 측정값을 비교하여 측정점 선정에 따른 환기성능 차이를 비교 조사하였다. 본 연구 결과는 향후 실환경 기반의 주거공간 실내 환기성능을 평가하기 위한 실험절차 개발을 위한 기초자료로 활용될 수 있을 것이다.

Ventilation plays an important role in controlling indoor air quality. Due to the recent spread of infectious diseases such as COVID-19 and with people spending more time indoors, there's been increased attention on the importance of ventilation performance. In many countries, ventilation is regulated by airflow rates and the number of air changes per hour (ACH). However, airflow rates and ACH alone do not provide an accurate account of actual indoor pollutant removal and ventilation uniformity in a space. This study looked into the ventilation performance of an actual residential unit using several sampling points instead of basing it off of airflow and air change rates. Literature review was used to derive relevant influencing factors and the tracer gas dilution method was used for the field test. The study measured air velocity, age of air, and ventilation efficiency at several locations and compared them to the average value at the center of the test space to determine the differences in ventilation performance at the selected measurement points. The study showed that different sampling locations resulted in different ventilation values. Findings of this study will be used to develop an experimental procedure for evaluating indoor ventilation performance of actual residential spaces.