• Wind and Structures
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• v.37 no.3
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• pp.211-227
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• 2023

To investigate the non-Gaussian feature of fluctuating wind pressures on rectangular high-rise buildings, wind tunnel tests were conducted on scale models with side ratios ranging from 1/9~9 in an open exposure for various wind directions. The high-order statistical moments, time histories, probability density distributions, and peak factors of pressure fluctuations are analyzed. The mixed normal-Weibull distribution, Gumbel-Weibull distribution, and lognormal-Weibull distribution are adopted to fit the probability density distribution of different non-Gaussian wind pressures. Zones of Gaussian and non-Gaussian are classified for rectangular buildings with various side ratios. The results indicate that on the side wall, the non-Gaussian wind pressures are related to the distance from the leading edge. Apart from the non-Gaussianity in the separated flow regions noted by some literature, wind pressures behind the area where reattachment happens present non-Gaussian nature as well. There is a new probability density distribution type of non-Gaussian wind pressure which has both long positive and negative tail found behind the reattachment regions. The correlation coefficient of wind pressures is proved to reflect the non-Gaussianity and a new method to estimate the mean reattachment length of rectangular high-rise building side wall is proposed by evaluating the correlation coefficient. For rectangular high-rise buildings, the mean reattachment length calculated by the correlation coefficient method along the height changes in a parabolic shape. Distributions of Gaussian and non-Gaussian wind pressures vary with side ratios. It is inappropriate to estimate the extreme loads of wind pressures using a fixed peak factor. The trend of the peak factor with side ratios on different walls is given.

• The Journal of Korean Medicine
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• v.44 no.3
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• pp.1-9
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• 2023

Objectives: The purpose of this study was to suggest the clinical characteristics and risk factors of facial palsy from the perspective of Korean Medicine. Methods: Medical records of 856 patients, who visited the Korean Medicine hospital with facial palsy from 2004 to 2019, were retrospectively analyzed. The clinical characteristics of facial palsy were suggested by figuring out the distribution of age, sex, occupation, onset season, obesity, modes, signs, symptoms, past and family history. Results: By gender, there were more males (54.6%), and the most common age groups were in their 50s (27.4%) and 40s (23.6%). As for the occupation, unemployed (27.7%) and service and sales workers (14.6%) were the most common, and the onset season was the most common in winter (28.9%). The most common clinical characteristics were overwork (33.0%), mental stress (24.8%), and exposure to cold (19.3%) in modes, 'none' (64.3%), postauricular pain (33.2%) in signs, postauricular pain (26.9%), parageusia (14.8%) in symptoms. Hypertension and diabetes were the most common in both past and family history. In particular, the obesity rate of the subjects (59.8%) was much higher than that of Koreans (32.8%). Conclusions: Based on the historical Korean Medicine literature and the results of this study, it is suggested that overwork, stress, exposure to cold, and obesity are identified as risk factors for facial palsy. Furthermore, dysfunction of the stomach meridian is thought to contribute to the cause of facial palsy.

• Environmental Analysis Health and Toxicology
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• v.11 no.1_2
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• pp.1-10
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• 1996

A decrease in stratospheric ozone probably caused by chloroflurocarbons (CFCs) emissions, has been observed large parts of-the globe. It is generally accepted that if ozone levels in the stratosphere are depleted, greater amounts of shortwave ultraviolet radiationB (UVB) will reach the earth's surface, resulting in increased incidence of nonmelanoma skin cancer. In this study, we evaluated several mathematical models, such as a power and an exponential model, and a geometric model considering the surface area of a human body part and ages for the prediction of Skin cancer incidence caused by exposure to the UVB radiation. These models basically estimated the risk of skin cancer based on those measurements of the local ozone in stratosphere and UVB. Both were measured at a part of Seoul with a Dobson ozone spectrometer and Robertson-Berger UV Biometer for 1995. As a result, we calculated the point estimation applying a biological amplification factor (BAF), UVB radiation and other factors. We used a Monte-Carlo simulation technique with assumption on the distribution of each considered factor. The sensitivity analysis of model by there components conducted using Gaussian sensitivity method. The annual integral of UVB radiation was 2275 MED (minimal erythema dose)/yr. Also, an estimate of the annual amount of UVB reaching the earth's surface at a korea's latitude and altitude was 3328 MED/yr. The values of the radiation amplification factor (RAF) were ranged from 0.9 to 1.5 in Seoul. To give the effective factors required to model the prediction of skin cancer incidence caused by exposure to the UVB radiation in Korea, we studied the pros and cons of above mentioned models with the application of those parameters measured in Seoul, Korea.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.20 no.4
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• pp.274-281
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• 2010

The objectives of this study are (a) to investigate the distribution patterns and exposure concentrations of biological agents in sawmill industries and (b) to compare sampling methods of biological agents. The representative processes of 5 sawmills were selected to measure total airborne bacteria, fungi, endotoxin as well as dust. Airborne bacteria and fungi were measured with one stage impactor, six stage impactor and gelatin filteration methods. Endotoxin was collected with polycarbonate filters and analysed by kinetic chromogenic Limulus Amebocyte Lysate method. Geometric mean levels of airborne bacteria, fungi, endotoxin and dust were 1,864 CFU/$m^3$, 2,252 CFU/$m^3$, 31.5 EU/$m^3$ and 2.4 mg/$m^3$. The ratios of indoor/outdoor concentrations were 3.7 for bacteria, 4.1 for fungi, 3.3 for endotoxin and 9.7 for dust. The respiratory fractions of bacteria were 68.0, 50.9, 49.2 and 45.1% in band-saw, table-saw, rip-saw process and outdoor air. The respiratory fractions of fungi were 78.7, 90.8, 87.5 and 84.8% in band-saw, table-saw, rip-saw process and outdoor air, respectively. There was no significant differences in bacterial concentrations among single stage, six stage impaction and filteration methods. But, fungal concentrations measured with filtration methods were significantly higher than those with impaction methods. Geometric mean levels of airborne bacteria and fungi were higher than the OSHA guideline values of 1,000 CFU/$m^3$. The respiratory fractions of fungi were above 75%. The concentrations of biological agents were significantly different among culture-based sampling methods. In the exposure assessments of biological agents, further studies are needed for the comparisons of diverse sampling methods and the investigations of environmental factors.

• Journal of the Korea Safety Management & Science
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• v.25 no.1
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• pp.7-14
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• 2023

We attempted to provide an overview of the laws and current state of the 3D printing industry in South Korea and around the world, using the annual industry surveys and the Wohler report. Additionally, we reviewed articles relating to the potential exposure to hazards associated with 3D printing using metal materials. In South Korea, there were 406 3D printing-related businesses, employing 2,365 workers, and the market size was estimated at 455.9 billion won in 2021. Globally, the average growth rate of the 3D printing industry market over the past 10 years was 27.4%, and the market size was estimated at $11.8 billion in 2019. The United States had the highest cumulative installation ratio of industrial 3D printers, followed by China, Japan, Germany, and South Korea. A total of 6,168 patents related to 3D printing were registered in the US between 2010 and 2019. Harmful factors during metal 3D printing was mainly evaluated in the powder bed fusion and direct energy deposition printing types, and there is a case of material extrusion type with metal additive filaments. The number, mass, size distribution, and chemical composition of particles were mainly evaluated. Particle concentration increases during the opening of the chamber or post-processing. However, operating the 3D printer in a ventilated chamber can reduce particle concentration to the background level. In order to have a safe and healthy environment for 3D printing, it is necessary to accumulate and apply knowledge through various studies.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.4
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• pp.325-339
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• 2022

Objective: This study was to perform to identify the distribution characteristics and related factors of work-related low back pain among manufacturing workers in Korea. Methods: We analyzed the third(2011) through sixth(2020) Korean Working Conditions Survey. This study examined changes in the prevalence of work-related low back pain among manufacturing workers and related factors, including demographic characteristics and working conditions. Results: The prevalence of work-related low back pain showed a general tendency to increase during the study periods except for the 5th wave. The prevalence of work-related low back pain was higher in women than in men. The prevalence increased with increasing age and decreased with higher educational attainment. This trend was observed in all survey waves. The prevalence ratios for work-related low back pain according to working conditions varied over the survey period. In general, workers with manual jobs, long working hours, and exposure to tired or painful postures showed relatively higher prevalence ratios than did their counterparts. Providing Information on health and safety, perception that work affects health, and experience of presenteeism were identified as influencing factors for work-related low back pain. Although the working environment is improving, work-related back pain is on the rise. A multifaceted study on risk factors for work-related low back pain is needed. Conclusion: Work-related low back pain is a significant factor affecting the working population's quality of life. The prevalence of work-related low back pain showed a tendency to increase during the study periods. A multifaceted study on risk factors for work-related low back pain is needed.

• International Journal of High-Rise Buildings
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• v.10 no.4
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• pp.345-364
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• 2021

Developments in the understanding of fire behaviour for large open-plan spaces typical of tall buildings have been greatly outpaced by the rate at which these buildings are being constructed and their characteristics changed. Numerous high-profile fire-induced failures have highlighted the inadequacy of existing tools and standards for fire engineering when applied to highly-optimised modern tall buildings. With the continued increase in height and complexity of tall buildings, the risk to the occupants from fire-induced structural collapse increases, thus understanding the performance of complex structural systems under fire exposure is imperative. Therefore, an accurate representation of the design fire for open-plan compartments is required for the purposes of design. This will allow for knowledge-driven, quantifiable factors of safety to be used in the design of highly optimised modern tall buildings. In this paper, we review the state-of-the-art experimental research on large open-plan compartment fires from the past three decades. We have assimilated results collected from 37 large-scale compartment fire experiments of the open-plan type conducted from 1993 to 2019, covering a range of compartment and fuel characteristics. Spatial and temporal distributions of the heat fluxes imposed on compartment ceilings are estimated from the data. The complexity of the compartment fire dynamics is highlighted by the large differences in the data collected, which currently complicates the development of engineering tools based on physical models. Despite the large variability, this analysis shows that the orders of magnitude of the thermal exposure are defined by the ratio of flame spread and burnout front velocities (V_S / V_BO), which enables the grouping of open-plan compartment fires into three distinct modes of fire spread. Each mode is found to exhibit a characteristic order of magnitude and temporal distribution of thermal exposure. The results show that the magnitude of the thermal exposure for each mode are not consistent with existing performance-based design models, nevertheless, our analysis offers a new pathway for defining thermal exposure from realistic fire scenarios in large open-plan compartments.

• Journal of Environmental Health Sciences
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• v.36 no.3
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• pp.171-181
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• 2010

Semivolatile aerosols exist as vapor and particles at the same time in room temperature and each phase has different intake and uptake mechanisms. This characteristic requires substantial consideration during exposure assessment of semivolatile aerosol. Some sampling methods for solid particles pose high possibility of evaporative loss during sampling. Therefore, when establishing sampling strategy for them, the factors affecting the phase distribution of semivolatile aerosol should be counted including semivolatile aerosol of interest and sampling methods used. Evaluation for phase distributions of semivolatile aerosols is also recommended. Metalworking fluids, pesticides, asphalt fumes, diesel exhaust, and environmental tobacco smoke are common health-related semivolatile aerosols in workplaces.

• Journal of Information Technology Services
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• v.13 no.2
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• pp.113-131
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• 2014

Smartphone security threat has become an important issue in Information Science field following the wide distribution of smartphones. However, there are few studies related to such. Therefore, this study examined the factors affecting the intention of smartphone users to use the mobile vaccine against malware with the Protection Motivation Theory. To secure the reliability of the study, a surveying agency was commissioned. A total of 263 respondents, excluding 37 respondents who are users of iOS, which does not have mobile vaccine in the smart phone, or who gave invalid responses, were surveyed. The results showed that perception of the installed mobile vaccine significantly affected the Response Efficacy and Self-efficacy, and that the Perceived Severity, Perceived Vulnerability, Response Efficacy, and Self-efficacy significantly influenced the intention to use the mobile vaccine. On the other hand, Installation Perception of mobile vaccine itself did not affect the Perceived Severity and Perceived Vulnerability. This study is significant since it presented the new evaluation model of threat evaluation and response evaluation in the Protection Motivation Theory in accepting the security technology and raised the need for the promotion and exposure of mobile vaccine, since perception of mobile vaccine installation affects the response evaluation. It also found that the promotion must consider the seriousness of smartphone security, outstanding attribute of mobile vaccine, and user-friendliness of mobile vaccine above all.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.5
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• pp.979-986
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• 2021

Online food delivery and food delivery apps have continued to grow exponentially in Malaysia. Fundamental aspects in entrepreneurship of the food and beverage industry, such as knowledge and attitudes towards online food delivery services being outsourced, have yet to be extensively recognized. The present study intends to explore this area of subject matter within the Malaysian context by using behavioral reasoning theory. The actual interview for this study took place in May 2020, and 14 interviews had been carried out. All interviews were audio-recorded with the consent from the respondents for reference purposes and subsequently transcribed verbatim. The transcripts were then checked against audio records. Content analysis was used to analyze the transcripts by focusing on n frequency counts and coding of themes. A qualitative method has been adopted by employing an interview to elicit the perspectives of entrepreneurs from Sarawak on the determinants and barriers in outsourcing online food delivery services. Results indicate that high potential in revenue, broad exposure to reach customers, convenience, and provision of job opportunities are the four factors that determine to outsource. In contrast, food quality maintenance, trustworthiness, high cost incurred, and consumer technology resistance are four factors that serve as barriers towards outsourcing third-party online delivery.