• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.1
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• pp.94-104
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• 2021

Objectives: A number of medical institutions have been conducting fit tests to perform seal checks on masks. This study aimed to compare the differences fit factor before and after domestic N95 mask-wearing training through a fit-test. Methods: A survey of 59 healthcare workers was conducted regarding whether they had undergone a fit test or received training on mask-wearing. Further, the fit of two types of domestic N95 masks was measured before and after the training using a QNFT(Quantitative Fit test). The average fit factors before and after training were compared using a paired t-test. Additionally the differences in the fit test pass rate were analyzed using a McNemar test. Results: A statistically significant difference was seen between the fit factors in the fit tests conducted before and after the training (p=0.0015), as well as in the fit of the two types of masks tested (p<0.01). Thus, an improvement in mask fitting was seen after the training, even with differently fitted masks. Conclusions: Upon using a QNFT, a significant increase in the fit factors for N95 masks was observed after training compared with masks that were fitted as usual. This highlights the importance of training in mask-wearing, with the conclusion that training healthcare providers will improve the fit of masks.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.6 no.1
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• pp.38-54
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• 1996

Respirator fit testing is required before entering specific work environmentals to ensure that the respirator worn satisfies a minimum of fit and that the user knows when the respirator fits properly. The fit of a respirator can be determined by qualitative (QLFT) or quantitative fit test (QNFT). The QNFT, having been universally accepted more than the QLFT, provide an objective and numerical basis by measuring a fit factor (FF). Until a few years age, only one QNFT technigue was available and accepted by U.S. Occupational Safety and Health Administration (OSHA) regulations. In the 1980's and 1990's, several new and fundamentally different QNFT methods were developed. Two of the newer methods are commercially availale and are accepted by OSHA as suitable alternatives. In this articles, the principle of operation of each ONFT technique is explained and each technique's major advantages and disadvantages are pointed out. Emphasis is given to negative-pressure air-purifying respirators, as they are in most frequent use today. The requirements and recommendations for fit testing positive-pressure respirators are discussed as well. Finally, the presently available QNFT standards and regulations are summarized to assist the user in making fit testing decisions.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.18
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• pp.8455-8460
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• 2016

Background: Poor participation rates are often observed in colorectal cancer (CRC) screening programs utilising faecal occult blood tests. This may be from dislike of faecal sampling, or having benign bleeding conditions that can interfere with test results. These barriers may be circumvented by offering a blood-based DNA test for screening. The aim was to determine if program participation could be increased by offering a blood test following faecal immunochemical test (FIT) non-participation. Materials and Methods: People were invited into a CRC screening study through their General Practice and randomised into control or intervention (n=600/group). Both groups were mailed a FIT (matching conventional screening programs). Participation was defined as FIT completion within 12wk. Intervention group non-participants were offered a screening blood test (methylated BCAT1/IKZF1). Overall participation was compared between the groups. Results: After 12wk, FIT participation was 82% and 81% in the control and intervention groups. In the intervention 96 FIT nonparticipants were offered the blood test - 22 completed this test and 19 completed the FIT instead. Total screening in the intervention group was greater than the control (88% vs 82%, p<0.01). Of 12 invitees who indicated that FIT was inappropriate for them (mainly due to bleeding conditions), 10 completed the blood test (83%). Conclusions: Offering a blood test to FIT non-participants increased overall screening participation compared to a conventional FIT program. Blood test participation was particularly high in invitees who considered FIT to be inappropriate for them. A blood test may be a useful adjunct test within a FIT program.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.1
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• pp.1-13
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• 1999

Even though there is no fit test regulations in Korea, in many developed countries, respirator fit testing is required before entering specific work environment to ensure that the respirator worn satisfies a minimum of fit and that the user knows when the respirator fits properly. Due to no regulation for fit test, a lot of Korean workers wearing respirators may be potentially exposed to hazards. Anthropometric test panels for testing the fit of respirators are very important to develop respirators fitted properly for Korean workers. To evaluate the fitting performance, 304 workers (272 males, 32 females) and 536 students (268 male, 268 females) were fit tested for 4 full-facepieces (2 domestic-made S, C, and 2 foreign-made T, N), 2 half masks (1 domestic-made S, and 1 foreign-made T) and 3 quarter masks (2 domestic-made S, C, and 1 foreign-made T) with PortaCount 8020. Fit factors of foreign-made masks were higher than those of domestic-made masks in all types. Males were fitted more properly than females. A facial dimension survey of 364 workers (339 males, 25 females) and 158 students (69 males, 89 females) was conducted to develop test panels for fit testing. Subjects were selected on the basis of face length and face width to wear full-facepiece masks in test. For testing half- and quarter masks, face length and lip length were used. Test panels containing 25 male-and-female subjects and 16 male subjects were respectively developed for full-facepiece, and half-and quarter masks to represent a majority of population surveyed.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.6 no.2
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• pp.176-186
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• 1996

The fit of a respirator to the face of an individual can be determined by a qualitative fit test (QLFT) or a quantitative fit test (QNFT). The pass/fail decision from a QLFT or QNFT for the same respirator on the same individual may vary from one wearing to the next, because the human facial features are complex and the respirator may not fit to the face in the same way every time it is worn. This study reports how the fit factors (FF) resulting from a QNFT on an individual vary from day to day and depend on the movements in the six fit test exercises. The reported FFs provide an objective and numerical basis (FF) which does not depend on the subject's voluntary or involuntary response. Four half-mask (H1-H4) and four full-facepiece respirators (F1-F4) were fit tested on one wearer 10 times a day for 5 days with a PortaCount (model 8010, TSI). The FFs obtained for each set of 10 fit tests on a specific day and 50 fit tests on five days involving one of the six exercise regimes have been recorded as log-normal distributions. All of the geometric standard deviations (GSD) of the overall FFs varied widely among every wearing and day except for H1 and F3, and the variability of the half-mask respirators was larger than that of the full-facepiece respirators. Among the six exercise regimes, reading or talking (RT) had markedly the lowest exercise FFs on the tested individual. Generally, there were significant differences between the first normal breathing (NB1) FFs and the remaining exercise FFs.

• Journal of the Korean Data and Information Science Society
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• v.9 no.2
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• pp.357-363
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• 1998

In this paper we propose a nonparametric lack of fit test based on the bootstrap method for testing the null parametric linear model by using linear smoothers. Most of existing nonparametric test statistics are based on the residuals. Our test is based on the centered bootstrap residuals. Power performance of proposed bootstrap lack of fit test is investigated via Monte carlo simulation.

• Journal of the Korean Data and Information Science Society
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• v.24 no.6
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• pp.1465-1475
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• 2013

The chi-square type test statistic is the most commonly used test in terms of measuring testing goodness-of-fit for multinomial logistic regression model, which has its grouped data (binomial data) and ungrouped (binary) data classified by a covariate pattern. Chi-square type statistic is not a satisfactory gauge, however, because the ungrouped Pearson chi-square statistic does not adhere well to the chi-square statistic and the ungrouped Pearson chi-square statistic is also not a satisfactory form of measurement in itself. Currently, goodness-of-fit in the ordinal setting is often assessed using the Pearson chi-square statistic and deviance tests. These tests involve creating a contingency table in which rows consist of all possible cross-classifications of the model covariates, and columns consist of the levels of the ordinal response. I examined goodness-of-fit tests for a proportional odds logistic regression model-the most commonly used regression model for an ordinal response variable. Using a simulation study, I investigated the distribution and power properties of this test and compared these with those of three other goodness-of-fit tests. The new test had lower power than the existing tests; however, it was able to detect a greater number of the different types of lack of fit considered in this study. I illustrated the ability of the tests to detect lack of fit using a study of aftercare decisions for psychiatrically hospitalized adolescents.

• Bulletin of the Korean Mathematical Society
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• v.53 no.2
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• pp.351-363
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• 2016

In this paper, we consider the entropy-based goodness of fit test (Vasicek's test) for a composite hypothesis. The test measures the discrepancy between the nonparametric entropy estimate and the parametric entropy estimate obtained from an assumed parametric family of distributions. It is shown that the proposed test is asymptotically normal under regularity conditions, but is affected by parameter estimates. As a remedy, a bootstrap version of Vasicek's test is proposed. Simulation results are provided for illustration.

• Communications for Statistical Applications and Methods
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• v.7 no.3
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• pp.811-816
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• 2000

The purpose of this paper is to study of data-driven smoothing goodness of it test, when the hypothesis is complete. The smoothing goodness of fit test statistic by nonparametric function estimation techniques is proposed in this paper. The results of simulation studies for he powers of show that the proposed test statistic compared well to other.

• Water for future
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• v.7 no.2
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• pp.99-106
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• 1974

The records of wave heights which were observed at Muk ho and Po hang of the East Coast of Korea were analized by several probility functions. The exponential 2 parameter distribution was found as the best fit probability function to the historical distribution of wave heights by the test of goodness of fit. But log-normal 2 parameter and log-extremal type A distributions were also fit to the historical distribution, especially in the Smirnov-Kolmogorov test. Therefore, it can't be always regarded that those two distributions are not fit to the wave heiht's distribution. In the test of goodness of fit, the Chi-Square test gave very sensitive results and Smirnov-Kolmogorov test, which is a distribution free and non-parametric test, gave more inclusive results. At the next stage, the inter-relationship between the mean and the one-third wave heights, the mean and the one-=tenth wave heights, the one-third and the one-tenth wave heights, the one-third and the highest wave heights were obtained and discussed.