• The Korean Journal of Applied Statistics
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• v.34 no.1
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• pp.1-8
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• 2021

Abstract concepts in social research must use measurement tools that are assured of validity and reliability. Observation score derived by a measurement tool can be divided into a valid observation score, a biased observation score, and an error. The presence or absence of a biased value is associated with validity, and the presence or absence of an error value is associated with reliability. There are many techniques for seeing whether a measurement tool is valid and reliable. For example, there are construct validity using factor analysis and internal consistency based on the Cronbach alpha. In this study, the calculation of the Cronbach alpha is derived through a sample, so we suggest an estimator of the Cronbach alpha under complex sample design and nonresponse. In a simulation, the proposed method is compared with many other existing estimators of Cronbach alpha under a multivariate normal distribution.

• Journal of the Korea Society of Computer and Information
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• v.28 no.5
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• pp.179-187
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• 2023

In this paper, we studied the impact of outliers on the power of the significance tests for Cronbach alpha reliability coefficient. Four variables were varied: sample size, the number of items, the number of outliers and population Cronbach Alpha levels. We simulated data using multivariate normal distribution and used outliers sampled from uniform distribution. To test the significance of Cronbach Alpha Reliability, parametric approach(F statistic) and permutation method were used. Consequently, we observed that the powers of permutation test are equal to or greater than those of F test under all conditions, and also both F test and permutation test lose the power as the number of outliers increases, and that these effects of outliers on the power are enhanced for increasing population alpha levels.

• The Journal of the Korea Contents Association
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• v.5 no.5
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• pp.266-272
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• 2005

This study is to empirically analyze the effects on job performance of Accounting Information Systems, Analysis methods were used to Cronbach's Alpha analysis, Factor analysis, analysis of variance(ANOVA) and regression in odor by the contingency grouping method. The results of this study are as follows : First, The regression analysis had effects on AIS utility and job performance. Second, The Analysis of variance(ANOVA) had non-effects on systems operating degree and systems satisfaction. Third, The input variables of information accuracy and systems satisfaction had additional effect about IT capability.

• Journal of the Korea Institute of Building Construction
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• v.17 no.6
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• pp.567-576
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• 2017

The purpose of this study is to analyze safety perception level of workers in construction site according to NOSACQ-50. To achieve the objective of this study, First, literature review is conducted to clearly define the concept of safety climate. Second, NOSACQ-50 is used to survey the level of safety climate of workers. Third, statistical analysis based on collected data is conducted to examine the level of safety climate. As a result, the level of safety climate in South Korea was found to be serious comparing with the standard value proposed in NOSACQ-50. Finally, the improvements were suggested after investigating the key factors on the level of safety climate. In the future, this study will be used as a baseline for developing safety awareness assessment tools such as NOSACQ-50 for domestic construction sites.

• Land and Housing Review
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• v.11 no.2
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• pp.47-57
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• 2020

In this study, we aimed to identify the latest trends of landscape in apartment complexes by identifying how landscaping spaces are being created and what their characteristics are. Furthermore, we aimed to find out what type of garden is being constructed in the landscaping space and what the difference between the landscaping space and the garden space is, and to define the future direction of landscape for apartment complexes. The following results were our findings. First, we identified that landscaping space is divided into general landscaping space and garden space. The garden space has designated area within the whole apartment complex as a garden and there is a variety of garden themes and plants, facilities, packaging patterns, and sculptures are used accordingly. On the other hands general landscaping space features uniform patterns of packaging and simple planting patterns. Our finding is that the current trend is to set up separate garden space within the landscaping space of apartment complexes. Although gardens are often regarded as personal property and spaces that need to be cultivated or managed, and spaces that are limited to fences are defined as gardens, the current landscaping space of apartments is creating gardens-like spaces within public spaces.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.395-395
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• 2019

대한민국에서 홍수는 매해 여름 발생하는 자연재해로 인명, 재산, 사회 기반시설에 심각한 피해를 일으키고 있으며, 기후변화로 인해 홍수 사상이 과거와는 다른 형태이다. 이를 대비하기 위해서는 기후변화를 고려한 홍수 위험도(flood risk)를 평가를 통해 적절한 대비책을 수립하여야 한다. 이에 본 연구는 전국의 홍수위험도를 중권역 별로 평가하는 홍수위험지수(Flood Risk Index, FRI)를 새로이 개발하였다. FRI는 세 가지 세부 지표인 위협도, 노출도, 대응능력(Hazard, Exposure, Capacity)의 결합으로 산정된다. 위협도는 직접적인 홍수의 원인이 되는 기상학적 요인인 강수에 대한 정보이고, 노출도는 홍수로부터 피해를 입을 수 있는 인명 및 재산에 대한 요소이다. 대응능력은 자연 환경과 인간의 중장기 전략을 고려한 적응능력(adaptive capacity)과 홍수 발생 시 조치능력(coping capacity)으로 나눠져 평가된다. 즉 위협도와 노출도가 높을수록 홍수 위험도가 커지며, 대응능력이 뛰어날수록 홍수 위험도는 줄어든다. 인자들은 특정 유형의 위험도에만 초점이 맞춰지지 않고 다양한 방면을 포괄적으로 평가할 수 있도록 선정되었으며, 통계 기법을 활용해 FRI를 산정하였다. 크론바흐 알파 계수(Cronbach's ${\alpha}$)를 통해 FRI의 타당성을 진단하였으며, 홍수피해금액간의 스피어만(Spearman) 상관계수를 통해 FRI의 설명력을 검증해 신뢰도를 제고했다. 최종적으로 환경부로부터 제공받은 미래 기후 시나리오를 사용하여 FRI를 산출해 미래의 세 시점(2030년대, 2050년대, 2080년대)의 전국 홍수위험도 평가를 진행하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.124-124
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• 2019

가뭄은 다른 자연재해들과 달리 복잡한 자연의 순환 시스템에 의해 발생하므로 시기가 명확하지 않으며, 사회 전반에 걸친 큰 규모의 피해가 발생한다. 이러한 피해를 저감하기 위해 가뭄에 대한 다양한 연구들이 진행되고 있다. 가뭄에 대한 기존 연구들을 살펴보면, 강수량과 같은 가뭄의 원인을 중점적으로 다룬 가뭄지수 연구가 대다수이다. 한편, 실제 가뭄 피해에 대한 연구들은 위험 혹은 취약성 분석으로 지수를 산정하는 방법으로 연구되고 있으며 농업 가뭄에 집중한 결과를 제시하고 있다. 본 연구에서는 가뭄 현상의 원인을 제공하는 기상학적 요인뿐 아니라 피해 대상과 대상의 내부시스템 능력에 따른 영향을 고려한 가뭄위험지수(Drought Risk Index, DRI)을 연구하였다. 또한, 생활용수, 농업용수, 공업용수를 고려하여 농업가뭄과 더불어 사회 경제학적 가뭄의 피해 평가가 가능한 통합 DRI를 산정하였다. 크론바흐 알파 계수를 통하여 지수 구성 요소들 간의 신뢰성과 DRI와 실제 가뭄 피해간의 스피어만 상관 계수를 사용하여 국내 유역에 대한 DRI의 타당성을 확인하였고 이를 통해 지수의 적합성을 분석하였다. 결과적으로 기후변화 시나리오를 사용하여 한반도의 2030, 2050, 2080년대 통합 DRI를 제시하였다.

• The Korean Journal of Applied Statistics
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• v.32 no.1
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• pp.15-27
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• 2019

The reliability of the data means the overall consistency of the measurement results. Methods for evaluating reliability have been continuously studied because it affects the results of the statistical analysis. Cronbach's ${\alpha}$ coefficient or intraclass correlation coefficient is used for reliability evaluation; however, these measures cannot be applied to data consisting of three-dimensional coordinates to represent an object. In this study, we propose a measure to evaluate the reliability of three dimensional shapes based on statistical shape analysis that is made possible by extracting the shape information from the measured three dimensional coordinates and decomposing the shape variation.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.3
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• pp.305-313
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• 2021

Purpose. The purpose of this pilot study is to evaluate the reliability and validity of the Korean version of the oral health impact profile (OHIP-EDENT K) for edentulous patients. Materials and methods. The study was conducted on 12 patients who fabricated overdenture in the Department of Prosthodontics, Korea University, Guro Hospital. All subjects completed the Korean version of Oral Health Impact Profile (OHIP K) questionnaire. Shorten version of the OHIP called OHIP-14 K and OHIP-EDENT K were derived from the datasets. Cronbach's alpha was used to measure internal consistency of the summary scores for OHIP-EDENT K. The Spearman's correlation coefficient between the summary scores for OHIP-EDENT K and OHIP K was calculated to evaluate concurrent validity. Results. The reliability of the summary scores for OHIP-EDENT K was acceptable (α=.736). The Spearman's correlation coefficient of the summary scores for OHIP-EDENT K and OHIP K was 0.966, which was statistically significant (P<.001). OHIP-EDENT K exhibited less susceptibility to floor effects than OHIP-14 K and appeared to measure change as effectively as OHIP K. In order to prove the reliability, responsiveness and validity of OHIP-EDENT K, further studies with more samples are needed. Conclusion. The OHIP-EDENT K, a questionnaire on oral health-related QOL comprising 19 items, has measurement properties comparable with the full 49-item version. This modified shortened version can be an alternative questionnaire to full version of OHIP K and OHIP-14 K in edentulous patients.

• Journal of the Korean Society of Radiology
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• v.17 no.4
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• pp.607-614
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• 2023

Clear overlapping of the bilateral epicondyle and proper separation of the elbow joint are crucial for obtaining accurate lateral general radiographs of the elbow. However, due to the complex anatomical structure of the elbow, achieving optimal positioning is challenging, leading to the need for repeated x-ray examinations. Therefore, the purpose of this study was to investigate the angle of the forearm in patients where accurate lateral images of the elbow joint can't be obtained after vertical incidence using a styrofoam device during elbow joint lateral x-ray imaging. Twenty patients were enrolled in our study following the established protocol. First, a vertical x-ray at an angle of 0° between the forearm and the table was taken (control group). Here, if the lateral image of the elbow joint was deemed inadequate, the forearm angle was adjusted using custom-made styrofoam supports with 5° and 10° inclinations (experimental groups). For the evaluation method, two assessors utilized a 5-point Likert scale to assess the images. The reliability of the assessments was analyzed using Cronbach's alpha coefficient. As a result, patients with inadequate overlap of the bilateral epicondyle and separation of the elbow joint in the initial examination (control group) were able to obtain the best images when setting a 10° angle between the forearm and the table. The subjective evaluation was 1.6 ± 0.8 points at 0°, 2.7 ± 0.8 points at 5°, and 4.4 ± 1.3 points at 10°, respectively. The reliability analysis for the angles of 0°, 5°, and 10° yielded Cronbach's alpha values of 0.867, 0.697, and 0.922, respectively. In conclusion, when it is not possible to obtain accurate images using the conventional position and X-ray beam direction, it is considered that by initially acquiring images with an angle of 10° between the forearm and the table, and gradually decreasing the angle while obtaining images, it would be possible to achieve the optimal image while reducing the number of repeat examinations.