• Journal of the Korean Home Economics Association
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• v.46 no.1
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• pp.39-45
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• 2008

We analyzed the effects of regular Jjimjilbang(Korean sauna) exposure on the physiological responses in seven elderly farmers(Male=3, Female=4). Jjimjil training group took a bath in Jjimjilbang 8 times twice a week. Jjimjibang exposure was limited three times per day. Rectal temperature, total sweat rate, body fat (%), blood pressure, pulse, $Na^+$ concentration in sweat, and subjective sensation were measured during Jjimjil training exposure. The results are as follow: During Jjimjil exposure, changes of rectal temperature in male farmers were more stabilized than female farmers. The gradual decrease in total sweat rate and Na+ concentration in sweat was observed in both sexes. After Jjimjil exposure, the decrease in blood pressure was observed in both sexes, but not observed changes according to regular Jjimjil exposure. Subjective thermal comfort sensation was changed positively. In conclusion, the regular Jjimjil exposure has positive effects upon improvement in regulation of body temperature, blood pressure, and $Na^+$ concentration especially in heat tolerance.

• Journal of the Korea Concrete Institute
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• v.25 no.1
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• pp.45-51
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• 2013

Short beam tests of GFRP and CFRP specimens exposed to high temperature were conducted to measure the inter-laminar shear strength. For the phase I test, the exposure time and temperature were varied to measure reduction in the strength due to the applied conditions. As a results, the critical temperature was found to $270^{\circ}C$ for the both FRP reinforcements. The high temperature, which causes 50% loss of inter-laminar shear strength, is defined as the critical temperature in this study. It should be noted that the critical temperature for the inter-laminar shear strength is mainly dependent on resin properties not on fiber type. In the phase II test, the effect of exposure time was investigated at intervals of 0.25hour for the critical temperature. All test results demonstrate that the exposure time effect is not significant compared to the maximum exposure temperature, but it is not negligible and, moreover, is significant at the critical temperature.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.4
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• pp.413-421
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• 2014

Since the structural temperature of a flight vehicle flying at high speed rises rapidly due to aerodynamic heating, it is necessary for optimum structural design to obtain proper material properties at high temperature by taking into account of its operational environment. For a special alloy, analysis data on strength change due to exposure time to high temperature are very limited, and most of them are for an exposure time longer than 30 minutes for long term operations. In this study, base and weld metal samples of Ti-6Al-4V alloy had been prepared and high temperature tensile tests with induction heating were performed, and then high temperature strength characteristics and strength recovery characteristics through cooling have been analyzed. Pre-tests to determine maximum heating rate were performed, and response characteristics for temperature control were confirmed. As a result, high temperature tensile strength appeared to be lower than that of room temperature, but it was higher than that of high temperature of 30 minite exposure listed in MMPDS. In strength recovery through cooling Ti-6Al-4V alloy has shown higher recovery rate compared with other alloys.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.2
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• pp.53-59
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• 2017

In this experimental study, the characteristic of damages on GFRP rebar exposed to high temperature only and immerged in alkaline solution after the exposure to high temperature was analyzed through microscopic image analysis. The found microcrack and pores in resin matrix were quantitatively compared if there was effect of pre-exposure to high temperature. The damages, such as microcrack and pores in resin matrix, by alkali exposure were mainly found in rebar surface. On the other hand, the pores caused by high temperatures were extensively found in a section and had greater width than those caused by the alkali exposure. In results of the quantitative comparison, the accumulated length and widths of microcrack and pores in resin matrix in pre-exposed GFRP rebar to high temperature were respectively 1.5 and 1.4 times of those in the GFRP rebar only immerged in alkali solution. Therefore, the deterioration of resin matrix by the alkali exposure could be accelerated due to the pre-exposure to high temperature.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.7
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• pp.963-968
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• 1998

A study was conducted to investigate the effect of cooling hands of feet on human thermoregulation in the cold. Eight young (22$\pm$1 yr) and eight aged (69$\pm$4 yr) men volun-teered as subjects They stayed at 1$0^{\circ}C$ in the supine posture during the experiment which included hands or feet exposure to the air for 20 minutes. Hand Exposure (HE) and Foot Exposure (FE) were conducted in radomized order and the baseline was kept before HE and FE. Core temperatures, limb skin temperatures adn thermal sensations were measured. Obtained data were analyze using t-test and correlation. Rectal and esophageal tem-peratures increased in the young (YG) and in aged (AG). Change rate of esophageal temperature (Tes) was maintained higher during FE than HE while rectal temperature showed no differences between YG and AG, and between HE and FE. Hand and foot skintemperature in YG and AG decreased similarly during HE and Fe. Forearm skin temperature during HE decreased while leg skin temperature during FE showed no change HE and Fe. It was concluded that the lower cooling. Furthermore, the increase of Tes was greater in young men than aged men. It is also suggested that the wearing behavior can be differently modified between young and aged men.

• Journal of the Korean Wood Science and Technology
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• v.27 no.4
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• pp.20-29
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• 1999

Temperature has important effect on mechanical properties of wood. These effect needs to be understood and taken into account in the structural use of wood. Furthermore, the effect of cooling after exposing to high temperature must be explained. In this study, the effect of temperature, exposure time, specific gravity, and cooling on bending properties were investigated. The boundary temperatures at which bending MOE and MOR reduced rapidly were approximately $200^{\circ}C$ and $150^{\circ}C$, respectively. This boundary temperature was nearly constant with independence of species(specific gravity), exposure time, and cooling. Above the boundary temperature, the effect of exposure time was increased with temperature and the reduction of bending MOE and MOR for Japanese Larch with relatively higher specific gravity was smaller than that of Hem-fir. The recovery of bending MOE and MOR after cooling was also more significant above the boundary temperature than below. The degree of cooling effect was larger for MOR than MOE. Consequently, bending properties of wood in elevated temperatures should be considered in terms of the boundary temperature, $200^{\circ}C$ for bending MOE, $150^{\circ}C$ for MOR, and these boundary temperatures must be considered an important factor. Furthermore, to evaluate the safety of structure, the recovery after cooling should be considered.

• The Journal of Fisheries Business Administration
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• v.47 no.4
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• pp.31-44
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• 2016

The purpose of this study is to analyze the climate change exposure of fisheries and fish species in the southern sea of Korea under the RCP climate change scenarios. The extent of exposure was calculated through weighted sum of the sea temperature forecasted by National Institute of Fisheries Science, and the weight were obtained from the time-space distribution of each fisheries or species, based on the micro-data for the fishing information reported by each fisherman. Results show that all the exposed sea temperature of RCP8.5 is higher than that of RCP4.5 in year 2100 as well as in near 2030, therefore it is thought to be very important to reduce the GHG emission even in the short term. The extent of exposure was analyzed to be comparatively high especially in the fisheries such as anchovy drag nets and species like cod, anchovy and squid. Meanwhile the method of this study is considered to be excellent to obtain the accurate extent of exposure under RCP scenarios, and therefore it is applicable on assessing the vulnerability of climate change in fisheries.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.1
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• pp.77-84
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• 2015

Tensile tests were conducted on the GFRP reinforcement exposed to high temperature. The exposure condition for this study was below $200^{\circ}C$ for about 3 minutes. This conditioning is minor compared with that presented in experimental program conducted by other researchers. The residual tensile strength and elastic modulus of GFRP reinforcing bars at high temperature and after exposure to high temperature were compared. In results, tensile properties were decreased at high temperatures, but those after exposure to high temperature were recovered to pre-heating level almost completely. These results could be valuable for evaluating GFRP reinforced structure damaged by fire accident.

• The Korean Journal of Community Living Science
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• v.18 no.4
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• pp.599-607
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• 2007

We analyzed the effects of regular Jjimjilbang (Korean sauna) exposure on the cold tolerance in young and elderly females. Subjects were young (n=7) and elderly (n=7) females who had never had Jjimjilbang exposure experience. The Jjimjil training group was exposured in the Jjimjilbang 19 times per week. Jjimjibang exposure was limited to three times per day. Jjimjil activity was taken freely. To prove the effects of the cold tolerance, subjects were exposed to cold air ($12{\pm}1^{\circ}C,\;60{\pm}10%$RH). In these conditions, subjects were exposed for 30 minutes at which time rectal temperature, skin temperatures, clothing microclimate, energy expenditure, blood pressure and subjective sensation were measured. To prove the effects of the local cold tolerance, vascular hunting reaction was observed measuring the finger skin temperature while the left middle finger tip was immersed in cold water of $0^{\circ}C$ for 30 minutes. The results are as follows. According to repeated Jjimjil exposure, rectal temperature changes, peripheral temperature and energy expenditure were increased gradually in the cold climate chamber. Blood pressure, subjective sensation and vascular hunting reactions did not show any significant difference. In conclusion, regular Jjimjilbang exposure has negative effects on the ability of the body to improve its regulation of temperature especially in cold tolerance.

• Journal of Korea Foundry Society
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• v.37 no.5
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• pp.139-147
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• 2017

Microstructural evolution of cast Hastelloy X during thermal exposure has been investigated. OM, SEM, and TEM microscopy were carried out on the as-cast, the standard heat treated, and the thermally exposed conditions. Tensile tests were also conducted to understand the effect of microstructural evolution on the degradation of tensile properties. Coarse $M_6C$ and fine $M_{23}C_6$ carbides were found in as-cast Hastelloy X with fine carbides on sub-boundary. Some of $M_{23}C_6$ carbide dissolved into the matrix during solution heat treatment and dislocation network formed at the interface between the carbide and the matrix due to the misfit strain. There was no significant microstructural difference between the exposed specimens at $400^{\circ}C$ and the solution heat treated specimen. A large amount of $M_{23}C_6$ carbides precipitated along and near grain boundaries and sub-boundaries after exposure at $650^{\circ}C$. Exposure at $870^{\circ}C$ of the alloy caused precipitation of $M_6C$ and ${\mu}$. The strength increased and the elongation decreased by thermal exposure at $650^{\circ}C$ and $870^{\circ}C$ because carbides interfere with the movement of the dislocation. It was found that the precipitation of carbide gave significant effects on the tensile properties of Hastelloy X.