• Structural Engineering and Mechanics
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• v.87 no.1
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• pp.1-18
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• 2023

The paper presents a Bayesian Finite element (FE) model updating methodology by utilizing modal data. The dynamic condensation technique is adopted in this work to reduce the full system model to a smaller model version such that the degrees of freedom (DOFs) in the reduced model correspond to the observed DOFs, which facilitates the model updating procedure without any mode-matching. The present work considers both the MPV and the covariance matrix of the modal parameters as the modal data. Besides, the modal data identified from multiple setups is considered for the model updating procedure, keeping in view of the realistic scenario of inability of limited number of sensors to measure the response of all the interested DOFs of a large structure. A relationship is established between the modal data and structural parameters based on the eigensystem equation through the introduction of additional uncertain parameters in the form of modal frequencies and partial mode shapes. A novel sampling strategy known as the Metropolis-within-Gibbs (MWG) sampler is proposed to sample from the posterior Probability Density Function (PDF). The effectiveness of the proposed approach is demonstrated by considering both simulated and experimental examples.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.141-148
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• 2012

A design of a 32-bit fourth-stage decimation filter decimation filter used in sigma-delta analog-to-digital (A/D) converter is proposed in this work. A four-stage decimation filter with down-sampling factor of 512 and 32-bit output is developed. A multi-stage cascaded integrator-comb (CIC) filter, which reduces the sampling rate by 64, is used in the first stage. Three half-band FIR filters are used after the CIC filter, each of which reduces the sampling rate by two. The pipeline structure is applied in the CIC filter to reduce the power consumption of the CIC. The Canonic Signed Digit (CSD) arithmetic is used to optimize the multiplier structure of the FIR filter. This filter is implemented based on a semi-custom design flow and a 130nm CMOS standard cell library. This decimation filter operates at 98.304 MHz and provides 32-bit output data at an audio frequency of 192 kHz with power consumption of $697{\mu}W$. In comparison to the previous work, this design shows a higher performance in resolution, operation frequency and decimation factor with lower power consumption and small logic utilization.

• Journal of Environmental Health Sciences
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• v.30 no.3
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• pp.272-282
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• 2004

Stress is a primary health promotion issue in worksite research because psychological distress is closely related not only to workers　 health status but also to their job performance. This study identified the work environment and work condition factors affecting workers　 stress symptoms among the Korean manufacturing factory workers. A total of 7,818 factory workers employed in 1,562 manufacturing companies participated in the Korean nation-wide occupational health survey conducted by the Korean Occupational Safety and Health Agency in 2003. Participants were selected by the stratified proportional sampling process by standardized industry classification, company size, and locations. Trained interviewers visited the target companies and interviewed the factory workers randomly selected in each company. Work environments included physical work environments (temperature, noise, hazardous organic compounds, and so on) and psychological work environments (job demands, job control, and social support at work), and work conditions included daily working hour, rest time, and so on. Men were 71.5% and the mean age was 34.0 years old. The average working period in the present company was 6.9 years. The average stress score was 26.2 under the perfect score, 50, which means the moderate level of stress. Perceived stress had significant correlations with young age, poor physical work environment, high fatigue, bad perceived health status, and high job demands in Pearson's simple correlation analysis. Perceived health status and perceived fatigue explained 21% variance of stress symptoms and the work environment factor explained 4.8% of that; however, work condition did not have the sufficient effect. In particular, psychosocial work environment variables (job demand, job control, and social support at work) had a clear effect on stress symptoms rather than the physical work environments. Poor perceived health status, severe perceived fatigue, poor physical work environment, high job demands, low social support, heavy alcohol consumption and little exercise were significantly related to high stress symptoms in the Korean manufacturing workers.

• Quality Improvement in Health Care
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• v.6 no.1_2
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• pp.92-106
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• 1999

Background : In many university hospitals, intravenous(IV) therapies and samplings had been one of the most important works of doctors who are in training. However, recently as patient oriented care is becoming more weighted for qualified health service IV therapies should be the works of specialized personnels. This study was conducted to investigate the medical staff's perception on IV team, to survey patient or parent's expectation on IV team, and to assess the frequency of IV therapy related complications and the characteristics of phlebitis among the hospitalized children. Methods : We collected data prospectively before the start of IV team from February 22 to February 29. 1999 and from September 27 to October 3, 1999, 6 months after beginning of IV team at Seoul National University Children's Hospital. IV team started their activities from March 1, 1999. General pediatric wards were not included for the IV and sampling team and oncology ward and surgical units were all included for the IV and sampling team's work. IV specialist was the well trained nurse who had been working in the field of pediatrics especially for the oncology patients. The subjects of this study were medical staffs who were working in children's hospital as doctors in training and patients who were treated with IV therapies in children's hospital during the same period. Results : Doctors responded that IV team need to be organized for IV care and expected IV team could reduce their work load. Parents of patients also responded IV team was very improtant to perform high quality IV care. They had willingness to pay extra charge for IV team care. In the wards where IV team did not work, they used various kinds and sizes of catheters, but in the wards where IV team worked, they needed just one or two types of catheters. As the exact role of IV team is not still established, job description is needed between the IV team and medical doctors. In the aspects of medical costs. it could save the materials for the IV also. Conclusion : This study showed that IV team could increase patient's satisfaction with decrease of medical doctors work load and concomitantly could save the costs of IV materials. And for the expansion of the IV team, job description is needed and for the total care of the children IV specialist and sampling team should expand their roles.

• Korean Journal of Occupational Health Nursing
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• v.19 no.2
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• pp.246-257
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• 2010

Purpose: The purpose of this study was to explore the factors related to physical and affective well-being of taxi drivers. The main factors of interests were workplace hazards and work environment. Method: This was a cross-sectional descriptive study. A convenience sampling method was utilized. 181 taxi drivers in Seoul metropolitan area completed survey questionnaires. Result: In bivariate analysis, payment system, workplace hazards, and work environment were associated with physical health of taxi drivers. Multiple regression analysis revealed payment system and workplace hazards were significant predictors of physical health. On the other hand, age and workplace hazards, and work environment were significantly associated with affective health in the bivariate analysis. Moreover, workplace hazards and environment were significant predictors of affective health in the multiple regression analysis. Conclusion: To improve taxi drivers' health status, it is critical to reform payment system to monthly payment, establish prevention policies of workplace hazards, and encourage employers and taxi drivers to make efforts for better work environment.

• Korean Journal of Occupational Health Nursing
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• v.30 no.2
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• pp.37-45
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• 2021

Purpose: This study aimed to investigate the influence of workplace violence experience on depression among female caregivers in Korea. Methods: This study was a secondary data analysis of data from the 5th Korean Working Conditions Survey (KWCS). The study sample consisted of 484 female caregivers. IBM SPSS 25.0 was used for complex sample analysis, which considered sampling the weights of variables. Based on the survey questions, we used complex sample cross-tabulation and the complex sample general linear model (CSGLM). Results: About 10.1% of female caregivers experienced workplace violence. The factors influencing workplace violence experience on depression were organizational justice (p=.048) and illness (p=.004). However, in cases with no violence, the influencing factors were psychological work environment (p=.001), work environment satisfaction (p=.024), and work engagement (p=.004). Conclusion: Caregivers are vulnerable to workplace violence. Therefore, it is necessary to formulate a policies such as organizational justice, work environment satisfaction, and work engagement to improve the working environment.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.1
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• pp.53-61
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• 2022

The goal of this research was to find the relationship between the work environment and societal issues that impede women's advancement to senior management positions. The study included 500 women professionals from diverse firms in Pakistan's business sector, of whom 100 were chosen as the sample size using a purposive sampling method. Experts confirmed the validity of the study tool, which was a questionnaire, and Cronbach's alpha coefficient was used to verify its reliability (0.704-0.982). The model's standardized regression coefficients suggested that social factors (0.298) were the most important factors determining women's empowerment in terms of career development and that they were further influenced by factors related to the work environment (0.411). It was concluded that organizational rules for female employees assist them to maintain a balance between work and family, resulting in a less stressful working environment. The role of the social factor as a mediator is also thought to be important in maintaining a healthier work environment in companies. It was also determined that much more work needs to be done on promotional regulations, as well as gender-blind legislation so that women's professional advancement is not limited to middle management.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.5
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• pp.462-473
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• 1999

This paper addresses the current measurement issue of all digital field oriented control of ac motors. The p paper focuses on the effect of low-pass filter and also on the sampling of the fundamental component of the m motor current. The low-pass filter, which suppresses the switching noise of the motor current, introduces v variable phase delay according to the current ripple frequency. It is shown that the current sampling error c consists of the fundamental component and high frL'quency ripple components. In this paper, the dependency of t this current sampling e$\pi$or on the reference voltage vector is investigated analytically and a sampling technique i is proposed to minimize the error. The work is based on the three phase symmetry pulse width modulation l inverter driving an induction machine. With this technique, the bandwidth of current regulator can be extended t to the limit given by the switching frequency of the inverter and more precise torque regulation is possible.

• Journal of Environmental Health Sciences
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• v.28 no.2
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• pp.109-116
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• 2002

The purpose of this study was to evaluate a new sampling and analytical method for the determination of airborne hexavalent chromium, Cr(Ⅵ), in a field plating operation. The procedures of this new method (Shin & Paik's Method) are as the following: Airborne hexavalent chromium is collected on polyvinyl chloride (PVC) filter according to the National Institute iota Occupational Safety and Health (NIOSH) Method 7600, and the filler sample is placed in a screw-capped vial and soaked with 2% NaOH/3% Na₂CO₃ solution immediately after sampling. The Cr(Ⅵ) sample is analyzed by ion chromatography/visible spectrophotometry (IC/VS) according to the U.S. Environmental Protection Agency (EPA) Method 218.6. The airborne Cr(Ⅵ) concentrations measured by this method were compared with those determined by three reference methods: One (NIOSH/EPA Method) consisted of sampling airborne Cr(Ⅵ) on PVC filters and storing the sample filters in strew-capped vials according to the NIOSH method, and analyzing Cr(Ⅵ) in samples using IC/VS according to the EPA method. The second method (Impinger Method/NaHCO₃) consisted of absorbing airborne Cr(Ⅵ) into 0.02 M NaHCO₃ solution in midget impinger, and analyzing the Cr(Ⅵ) in samples using IC/VS. The third method was the OSHA Method ID-215. Using these four different methods, lour replicates of air samples were collected at an electroplating process and analyzed simultaneously. Two-way ANOVA and paired t-test were used to test difference among values determined by the methods. There was no significant difference and a strong correlation (r²:0.99) between Cr(Ⅵ) concentrations measured by the Shin & Paik's Method and an impinger method (p>0.05). However, Cr(Ⅵ) concentrations determined by Shin & Paik's Method were significant1y different from those by the NIOSH/EPA Method (p<0.05) or the OSHA method (p<0.05). The Cr(Ⅵ) concentrations of Shin & Paik's Method were significantly higher than those of the NIOSH/EPA Method or the OSHA method. This result indicated that the Shin & Paik's Method may prevent Cr(Ⅵ) losses caused by reduction and give more reliable results of airborne Cr(Ⅵ) concentrations in work environments.

• Advances in aircraft and spacecraft science
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• v.6 no.6
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• pp.529-550
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• 2019

The effect of multiple process parameters on a set of continuous response variables is, especially in experimental designs, difficult and intricate to determine. Due to the complexity in aeroacoustic and vibroacoustic studies, the often-performed simple one-factor-at-a-time method turns out to be the least effective approach. In contrast, the statistical Design of Experiments is a technique used with the objective to maximize the obtained information while keeping the experimental effort at a minimum. The presented work aims at giving insights on Design of Experiments applied to aeroacoustic and vibroacoustic problems while comparing different experimental designs and approximation models. For this purpose, an experimental rig of a ducted low-pressure fan is developed that allows gathering data of both, aerodynamic and aeroacoustic nature while analysing three independent process parameters. The experimental designs used to sample the design space are a Central Composite design and a Box-Behnken design, both used to model a response surface regression, and Latin Hypercube sampling to model an Artificial Neural network. The results indicate that Latin Hypercube sampling extracts information that is more diverse and, in combination with an Artificial Neural network, outperforms the quadratic response surface regressions. It is shown that the Latin Hypercube sampling, initially developed for computer-aided experiments, can also be used as an experimental design. To further increase the benefit of the presented approach, spectral information of every experimental test point is extracted and Artificial Neural networks are chosen for modelling the spectral information since they show to be the most universal approximators.