• Advances in materials Research
• /
• v.9 no.4
• /
• pp.289-309
• /
• 2020

The aim of the present investigation is to examine the propagation of plane harmonic waves in transversely isotropic homogeneous magneto visco thermoelastic rotating medium with fractional order heat transfer and two temperature. It is found that, for two dimensional assumed model, there exist three types of coupled longitudinal waves (quasi-longitudinal, quasi-transverse and quasi-thermal) in frequency domain. phase velocities, specific loss, penetration depth, attenuation coefficients of various reflected waves are computed and depicted graphically. The effects of viscosity and fractional order parameter by varying different values are represented graphically.

• Structural Engineering and Mechanics
• /
• v.25 no.5
• /
• pp.597-611
• /
• 2007

Many works have been done in classical theory of thermoelasticity in materials with memory by researchers like Nunziato, Chen and Gurtine and many others. No work is located in generalized thermoelasticity regarding materials with memory till date. The present paper deals with the wave propagation in materials with memory in generalized thermoelasticity. Plane progressive waves and Rayleigh waves have been discussed in details. In the classical theory of heat conduction it was observed that heat propagates with infinite speed. This paradox has been removed in the present discussion. The set of governing equations has been developed in the present analysis. The results of wave velocity and attenuation coefficient corresponding to low and high frequency have been obtained. For thermal wave the results show appreciable differences with those in the usual thermoelasticity theory.

• Journal of Mechanical Science and Technology
• /
• v.17 no.10
• /
• pp.1533-1542
• /
• 2003

In the present study, the characteristics of pressure oscillation and heat transfer performance in an oscillating capillary tube heat pipe were experimentally investigated with respect to the heat flux, the charging ratio of working fluid, and the inclination angle to the horizontal orientation. The experimental results showed that the frequency of pressure oscillation was between 0.1 Hz and 1.5 Hz at the charging ratio of 40 vol.%. The saturation pressure of working fluid in the oscillating capillary tube heat pipe increased as the heat flux was increased. Also, as the charging ratio of working fluid was increased, the amplitude of pressure oscillation increased. When the pressure waves were symmetric sinusoidal waves at the charging ratios of 40 vol.% and 60 vol.%, the heat transfer performance was improved. At the charging ratios of 20 vol.% and 80 vol.%, the waveforms of pressure oscillation were more complicated, and the heat transfer performance reduced. At the charging ratio of 40. vol.%, the heat transfer performance of the OCHP was at the best when the inclination angle was 90$^{\circ}$ the pressure wave was a sinusoidal waveform, the pressure difference was at the least, the oscillation amplitude was at the least, and the frequency of pressure oscillation was the highest.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.15 no.5
• /
• pp.422-431
• /
• 2003

Theory of the building heat transfer is generally limited to the heat flux to the surfaces of windows and walls, which influences the indoor climate of a building, in the field of architectural environmental engineering. While the heat flux from the buildings to their environment has been considered in the viewpoint of urban climate, its conventional theory have been rarely examined. The purpose of this study is to propose a building-urban heat transfer model for defining the relation between the building and the urban climate by extending the building heat transfer model. In this study, the extended building heat transfer model, where response factor method is used, is established on the urban space and the indoor space by the boundary of building envelopes. Computer simulation (HASP/ACLD) is conducted on the subjected urban area by the established building-urban heat transfer model. As a result it is logically proved that the short waves of solar radiation, which interact with long Waves of radiation from the buildings and the earth, increase the urban air temperature ana buildings largely influence on the urban climate.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.25 no.6
• /
• pp.678-686
• /
• 2019

In this study, marine heat waves on coastal waters of Republic of Korea were detected using satellite-based Sea Surface Temperature Anomaly (SSTA). The detected results were compared with the warm water issues reported by the National Institute of Fisheries Science (NIFS). Marine heat waves detection algorithm using SSTA based on a threshold has proposed. The threshold value was defined as 2℃ for caution and 3℃ for warning issues, respectively. Daily averaged SST data from July to September of 2017-2018 were used to generate SSTA. The satellite-based detection results were classified into nine areas according to the place names used in the NIFS warm water issues. In the comparison of frequency of marine heat waves occurrence to each area with the warm water issue, most areas in the southern coast showed a similar pattern, that is probably NIFS uses spatially well distributed buoys. On the other hand, other sea areas had about two times more satellite detection results. This result seems to be because NIFS only considers the water temperature data measured at limited points. The results of this study are expected to contribute to the development of a satellite-based warm/cold water monitoring system in coastal waters.

• Journal of Wellbeing Management and Applied Psychology
• /
• v.7 no.2
• /
• pp.49-56
• /
• 2024

Purpose: Construction sites are currently facing a socialization problem as the incidence of thermal disease-related disasters increases due to summer heat waves, exacerbated by factors like the concentration of middle-aged and older workers and global warming. The reason why construction sites are particularly vulnerable to heat waves is that there are many outdoor work, which is the peculiarity of the construction industry, and most of the construction workers are elderly. This study analyzes disaster statistics of workers at construction sites for five years to investigate the occurrence of thermal diseases and analyze factors through disaster cases to provide basic data for future disasters to be reduced. Research design, data, and methodology: According to the Construction Workers' Mutual Aid Association, as of June, more than 60% of the construction workers working in the field were in their 50s and 60s. More than 24% are in their 60s and older. Thermal diseases caused by heat waves occur when exposed to high heat or strong sunlight for a long time, accompanied by headaches and dizziness. The problem is that many elderly people have underlying diseases, so if they lose consciousness, they cannot easily recover and are likely to die. Results: According to industrial accident statistics, 182 people were injured by heat-related diseases in the summer from 2016 to 2021, of which 29 died. In particular, in the construction industry, which has a lot of outdoor work, 87 people were injured and 20 people died. Conclusions: In order to prevent heat diseases caused by outdoor work, it is emphasized that exposure time is controlled, and sufficient rest and hydration are essential. Rest, water, and shade are in line with the three principles.

• Journal of Energy Engineering
• /
• v.13 no.2
• /
• pp.152-160
• /
• 2004

The present study investigates on the experimental and numerical results of heat transfer in the acoustic fields induced by ultrasonic waves. The strong upwards flow which moves from the bottom surface in a cavity to the free surface called as "acoustic streaming" was visualized by a particle image velocimetry (PIV). In addition, the augmentation ratio of heat transfer was experimentally investigated in the presence of acoustic streaming and was compared with the profiles of acoustic pressure calculated by the numerical analysis. A coupled finite element-boundary element method (FE-BEM) was applied for a numerical analysis. The results of experimental and numerical studies clearly show that acoustic pressure variations caused by ultrasonic waves in a medium are closely related to the augmentation of heat transfer.

• Journal of Environmental Policy
• /
• v.14 no.3
• /
• pp.21-40
• /
• 2015

Heat waves are not new, but due to climate change, the probability of occurrence and severity of heat waves increases, which results in more adverse impacts and damages on local community. Accordingly, the need to tackle heat waves in a more comprehensive and precautionary manner increases. Our study therefore lays emphasis on 1) a long-term plan which not only includes short-term plans in response to the observed damages, but also incorporates relevant sectors to deal with potential impacts in longer term perspective; and 2) a mechanism to manage and adjust the plan in a sustainable manner. In doing so, it examines the impacts of heatwaves and existing plans to tackle them. Based on that, two key conceptual frameworks, namely policy integration and adaptive management, are applied to provide strategies for the development and management of a long-term adapting heatwave plan addressing climate change.

• Journal of Environmental Science International
• /
• v.25 no.7
• /
• pp.951-961
• /
• 2016

To prevent increasing instances of heat-related illnesses due to heat waves generated by climate change, a customized thermal environment index should be developed for outdoor workers. In this study, we conducted sensitivity analysis of the Masan harbor during a heat wave period (August 9th to 15th, 2013) using the MENEX model with metabolic rate and clothing-insulation data, in order to obtain realistic information about the thermal environment. This study shows that accurate input data are essential to gather information for thermophysiological indices (PST, DhR, and OhR). PST is sensitive to clothing insulation as a function of clothing. OhR is more sensitive to clothing insulation during the day and to the metabolic rate at night. From these results, it appears that when exposed to high-temperature thermal environments in summer, wearing highly insulated clothing and getting enough rest (to lower the metabolic rate) can aid in preventing heat-related illnesses. Moreover, in the case of high-intensity harbor work, quantification of allowed working time (OhR) during heat waves is significant for human health sciences.

• Atmosphere
• /
• v.19 no.4
• /
• pp.309-318
• /
• 2009

Vulnerability to heat was examined for populations of 6 major cities in South Korea (Seoul, Incheon, Daejeon, Gwangju, Daegu, and Busan). Daily excess mortality and maximum temperature from 1991 to 2005 were employed in this study. The results show that the standardized mortality increase associated with a $1^{\circ}C$ increase in daily maximum temperature above the city-specific threshold explains the heat acclimatization effect better than the threshold temperature itself. The estimated increase in mortality (standardized per 10 million population) associated with a $1^{\circ}C$ increase in temperature above the threshold is 4.8 in Incheon, 4.7 in Seoul, 4.3 in Daejeon, 2.8 in Gwangju, 2.4 in Daegu, and 1.5 in Busan, well reflecting the latitudinal locations and local climates of each city. Climate models project more frequent, more intense, and longer lasting heat waves in most land areas in both hemispheres in the 21st century under increasing greenhouse gas concentrations. In order to mitigate the adverse human health impacts due to excess heat, more detailed characteristics of acclimatization to heat need to be understood and quantified.