Analysis of differences in variables related to health and safety according to the employment type of Korean workers

Introduction: The purpose of this study was to understand the differences in variables related to health and safety according to the employment type of Korean workers, specifically to identify the differences by employment type on in health status, the likelihood of wearing protective gear when working, access to manuals on emotional expression, and access to information on risk factors related to health and safety. Methods: The secondary data of four items on employment type, health type of workers and safety among the 5th Korean Working Condition Survey conducted in 2017 in Korea was used in this study. The data of workers were processed by using SPSS/WIN 23.0 Program and R 3.1.2, and demographic characteristics were quantified as frequency and percentage.  Results: A total of 30,300 employed people were surveyed. The result shows that part-time workers have poorer health than full-time workers (c2 = 540.7155, p < 0.05), insufficiently wore protective gear (c2 = 24.8702, p < 0.05), had insufficient access to manuals on emotional expression (c2 = 27.7612, p < 0.05) and lacked information about risk factors (c2 = 185.0082, p < 0.05). Conclusion: Health and safety manager will need to have education and consultation, development of manual and perform an early intervention to improve safety environment as primary health care providers by understanding factors related to health and safety of part-time workers

Differentially Private Multivariate Statistics with an Application to Contingency Table Analysis

Differential privacy (DP) has become a rigorous central concept in privacy protection for the past decade. Among various notions of DP, $f$-DP is an easily interpretable and informative concept that tightly captures privacy level by comparing trade-off functions obtained from the hypothetical test of how well the mechanism recognizes individual information in the dataset. We adopt the Gaussian differential privacy (GDP), a canonical parametric family of $f$-DP. The Gaussian mechanism is a natural and fundamental mechanism that tightly achieves GDP. However, the ordinary multivariate Gaussian mechanism is not optimal with respect to statistical utility. To improve the utility, we develop the rank-deficient and James-Stein Gaussian mechanisms for releasing private multivariate statistics based on the geometry of multivariate Gaussian distribution. We show that our proposals satisfy GDP and dominate the ordinary Gaussian mechanism with respect to $L_2$-cost. We also show that the Laplace mechanism, a prime mechanism in $\varepsilon$-DP framework, is sub-optimal than Gaussian-type mechanisms under the framework of GDP. For a fair comparison, we calibrate the Laplace mechanism to the global sensitivity of the statistic with the exact approach to the trade-off function. We also develop the optimal parameter for the Laplace mechanism when applied to contingency tables. Indeed, we show that the Gaussian-type mechanisms dominate the Laplace mechanism in contingency table analysis. In addition, we apply our findings to propose differentially private $\chi^2$-tests on contingency tables. Numerical results demonstrate that differentially private parametric bootstrap tests control the type I error rates and show higher power than other natural competitors

Experimental Performance Evaluation of a MR Brake-Based Haptic System for Teleoperation

In this work, a new type of haptic system inspired by human wrist motion is proposed, and its performance is evaluated experimentally for teleoperation. The master device has 3-DOF rotational motion, which is the same as human wrist motion; semi-active magnetorheological brakes are installed to generate a haptic effect for the operator. To achieve a good haptic feedback effect, the master device is designed with a lightweight structure and the haptic actuator is designed with minimal size. The slave robot has 3-DOF rotational motion using servomotors, a five-bar linkage mechanism, and a pivot point. In the proposed slave robot, instead of a commercial torque sensor, a newly designed torque sensor that uses three force sensors is adopted. It is experimentally validated that the proposed haptic system has good performance in terms of the tracking control of the desired position and repulsive torque. In addition, to ensure that the human operator can actually distinguish the different magnitudes of torque, a simple recognition test is carried out. Although not continuous, it is confirmed that the torque difference can be distinguished at three levels. Finally, it is demonstrated that the proposed haptic system can be effectively applied to a real teleoperation system