• Journal of Environmental Science International
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• v.28 no.7
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• pp.617-627
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• 2019

This study investigated the relationship between heat-related illnesses obtained from healthcare big data and daily maximum temperature observed in seven metropolitan cities in summer during 2013~2015. We found a statistically significant positive correlation (r = 0.4~0.6) between daily maximum temperature and number of the heat-related patients from Pearson's correlation analyses. A time lag effect was not observed. Relative Risk (RR) analysis using the Generalized Additive Model (GAM) showed that the RR of heat-related illness increased with increasing threshold temperature (maximum RR = 1.21). A comparison of the RRs of the seven cities, showed that the values were significantly different by geographical location of the city and had different variations for different threshold temperatures. The RRs for elderly people were clearly higher than those for the all-age group. Especially, a maximum value of 1.83 was calculated at the threshold temperature of $35^{\circ}C$ in Seoul. In addition, relatively higher RRs were found for inland cities (Seoul, Gwangju, Daegu, and Daejeon), which had a high frequency of heat waves. These results demonstrate the significant risk of heat-related illness associated with increasing daily maximum temperature and the difference in adaptation ability to heat wave for each city, which could help improve the heat wave advisory and warning system.

• Journal of the Korean association of regional geographers
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• v.22 no.1
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• pp.195-210
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• 2016

The purpose of this study was to understand characteristics of groups vulnerable to extreme heat and to reduce mortality caused by high temperature. For this purpose, relationship between socioeconomic factors and mortality-threshold temperatures were studied. The study area was limited to Seoul (South Korea) and climate data from 2000 to 2010 was used. Our results indicate that mortality-threshold temperatures for regions with a high proportion of aging population and a low proportion of aging population are $27.6^{\circ}C$ and $27.9^{\circ}C$, respectively. It was also found that a relative size of welfare dependant population did not affect mortality-threshold temperatures. However, regions with a high proportion of aging and welfare dependant population experienced $0.7^{\circ}C$ lower mortality-threshold temperature than other regions. This implies that low income and older people in Seoul are more easily affected by high temperature. Thus, this study suggests that it needs a policy targeted to low income and aging population to decrease mortality rate caused by extreme heat.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.1
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• pp.115-124
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• 1989

Near-threshold fatigue crack-growth behavior at room temperature for a duplex stainless steel weldments was investigated to evaluate the effect of load ratio, microstructural change, and residual stresses. Near-threshold fatigue crack propagation behavior is found to show a marked sensitivity to .alpha./.gamma. phase ratio, and little residual stress effects. Threshold values in the heat affected zones are higher than those of base metals and threshold values for crack growth decrease with increasing the load ratio in the base metals and weldments. The fractrographic features in base metals, weldments and heat affectred zones were discussed in terms mechanism of crack growth.

• Polymer(Korea)
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• v.27 no.1
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• pp.40-45
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• 2003

In this work, the effect of different contents of $Fe_3O_4$ and temperature variation on the electrical conductivity ($\sigma$) in the polar acrylonitrile butadiene rubber (NBR)/$Fe_3O_4$ (magnetite) mixture system was investigated. It was found that the percolation threshold concept holds true for the conductive particle-filled composites where $\sigma$ indicates a nearly sharp increase when the concentration of magnetite in the mixture exceeds 22%. The temperature dependence of $\sigma$ was thermally activated below and at the percolation threshold ($P_c$). Magnetite acted as reinforcing and conductive filler for NBR. At room temperature and higher voltages, the electrical current was proportional to the square of voltage ($I{\propto}V^2$) for the composites which contain 30 phr of magnetite. Moreover, it was shown that the composites with magnetite of 50 phr showed the highest tensile strength and elongation at break, which was due to the formation of optimal physical interlock and crosslinking. The results of 100%, 200%, and 300% Young moduli said that the moduli are largely correlated with reinforcement effect of magnetite and viscosity of the blends from torque curve.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.682-684
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• 2003

In this paper, we have designed the p-type SiGe MOSFET and analyzed the electrical characteristics over the temperature range of 300K and 77K. When the gate voltage is biased to -1.5V, the threshold voltage values are -0.97V and -1.15V at room temperature and 77K, respectively. We know that the operating characteristics of SiGe MOSFET is superior to the basic Si MOSFET which the threshold voltage is -1.36V.

• Advanced Composite Materials
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• v.16 no.3
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• pp.195-206
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• 2007

Carbon nanofiber (CNF)/unsaturated polyester resin (UPR) was prepared by a solvent evaporation method, and the temperature dependency of electrical conductivity was investigated. The CNF/UPR composites had quite a low percolation threshold due to CNF having a larger aspect ratio and being well dispersed in the UPR matrix. The positive temperature coefficient (PTC) was found in the CNF/UPR composites and it showed stronger effect around the percolation threshold. The electrical resistance of the CNF/UPR composites decreased and had lower temperature dependency with increasing numbers of thermal cycles.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.474-477
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• 2003

In this paper, we have designed the p-type SiGe MOSFET and analyzed the electrical characteristics over the temperature range or 300K and 77K. When the gate voltage is biased to -1.5V, the threshold voltage values are -0.97V and -1.15V at room temperature and 77K, respectively. We know that the operating characteristics of SiGe MOSFET is superior to the basic Si MOSFET which the threshold voltage is -1.36V.

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.88-93
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• 2020

Based on the capture-emission energy (CEE) maps of CMOS devices, a physics-informed machine learning model for the bias temperature instability (BTI)-induced threshold voltage shifts and low frequency noise is presented. In order to incorporate physics theories into the machine learning model, the integration of artificial neural network (IANN) is employed for the computation of the threshold voltage shifts and low frequency noise. The model combines the computational efficiency of IANN with the optimal estimation of Gaussian mixture model (GMM) with soft clustering. It enables full lifetime prediction of BTI under various stress and recovery conditions and provides accurate prediction of the dynamic behavior of the original measured data.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.29-33
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• 2010

We have investigated fs-laser ablation as well as optoperforation threshold of PDMS (Polydimethylsiloxane) thin lid cover on ${\mu}$-channel with changing the flow medium from water to hemoglobin. The ablation threshold is found to be independent of both PDMS thin film thickness and flow medium, but the optoperforation threshold is dependent on the films thickness. The observation that the ablation process is well described with simple two-temperature model supposed that the cover lid PDMS of $\mu$-channel be processed with minimized thermal effects by fs-laser with low laser fluence.

• Applied Science and Convergence Technology
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• v.23 no.1
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• pp.34-39
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• 2014

The programmable switches which control the delivery of electrical signals in programmable logic devices are fabricated using memory technology. Although phase change memory (PCM) technology is one of the most promising candidates for the manufacturing of the programmable switches, the threshold switching material should be added to a PCM cell for realization of the programmable switches based on PCM technology. In this work, we report the impurity-doped $Ge_2Sb_2Te_5$ (GST) chalcogenide alloy exhibiting threshold switching property. Unlike the GST thin film, the doped GST thin film prepared by the incorporation of In and P into GST is not crystallized even at the postannealing temperature higher than $200^{\circ}C$. This specific crystallization behavior in the doped GST thin film is attributed to the stabilization of the amorphous phase of GST by In and P doping.