• Journal of Korean Society of Steel Construction
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• v.16 no.4 s.71
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• pp.433-442
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• 2004

This paper discusses the development of a computer program to analyze elastic local buckling stress based on Eurocode 3 Part 1.3 for the flange and web of cold-formed channel columns under compression at elevated temperatures. The high-temperature, stress-strain relationships of the steel used in this paper were determined according to Eurocode 3 Part 1.2. The critical temperatures and the elastic local buckling stresses of cold-formed channel columns under compression at elevated temperatures were analyzed with the computer program developed in this study. Analysis examples were given to show the applicability of the computer program.

• Journal of Korean Society of Steel Construction
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• v.16 no.1 s.68
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• pp.103-111
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• 2004

This paper dealt with the local buckling of H-beams investigated mainly using the parameters of load ratios. load conditions, and support boundary condition considering predicted uniformly elevated temperatures. The physical properties of the material at elevated temperatures followed EC3 Park 1.2. The local buckling of the plates in steel beams show that they are governed by the yield stress or the critical stress of the steel plates according to the ratios of b/tf, d/tw. The evaluation of uniformly heated steel beams on the local buckling considered the stress and moment ratios to the LRFD.

• Journal of Korean Society of Steel Construction
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• v.17 no.4 s.77
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• pp.491-498
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• 2005

This study involves the development of a computer program to analyze the local buckling stresses for the flange and the web of I-beams under compression at elevated temperatures, and the optimization algorithm to analyze the optimum width-thickness ratios which does not occur their local buckling prior to yield failure. The high-temperature stress-strain relationships of steel used in this study were based on EC3 (Eurocode3) Part1.2 (2000b). In this study, the local buckling stresses and the optimum width-thichness ratios were analyzed considering the influences of the yield stress, local buckling coefficients and width-thickness ratios of the flange and the web. Design examples show the applicability of the computer program developed in this study.

• Korean Journal of Materials Research
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• v.11 no.7
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• pp.585-589
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• 2001

Many experimental results have revealed that the development of cavitaition during tensile deformation is limited by the Presence of liquid phases. However, the presence of liquid phases does not always lead to high-strain-rate superplasticity, because too much liquid causes intergranular decohesion at grain boundaries/interfaces in metal-matrix composites. Thus, it is important to examine the nature of interfaces of superplastic composites in order to understand the origin of superplastic flow related to liquid grain boundaries during high-strain-rate superplastic deformation. This study shows that a large elongation is obtained at the temperature, that is close to the onset temperature for partial melting in the superplastic composites, but the elongation significantly decreases at slightly higher temperatures, which are close to the end temperature fur partial melting. This indicates that there is an optimum amount of the liquid phase for obtaining high-strain-rate superplasticity in these materials.

• Journal of Korean Association for Spatial Structures
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• v.12 no.3
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• pp.55-62
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• 2012

본 연구는 온도 증가에 따른 압축을 받는 H형 강재의 플랜지와 웨브의 국부 및 전체좌굴응력 내화해석 프로그램 개발과 플랜지와 웨브가 항복파괴전에 국부좌굴이 일어나지 않을 한계 판폭두께비의 상관값을 구하는 프로그램을 개발하는 것이다. 고온에서의 강재의 응력-변형도 관계식은 EC3:Part 1.2를 근거로 하였으며, 비교, 검토를 위하여 영국 BS5950의 강재를 대상으로 온도 증가에 따른 압축을 받는 강재의 플랜지와 웨브의 파괴온도와 하중을 본 연구의 내화해석 프로그램으로 예측하였다. 본 연구는 좌굴 및 항복에 대한 내화해석 프로그램을 개발하는 것을 목적으로 하고 적용 예를 통하여 좌굴 및 한계 판폭두께비를 분석하고 개발 프로그램의 타당성을 검토하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.319-324
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• 2011

This study aims to investigate statistical variations and relationships of blood pressure (BP), phtotplethysmography (PPG) and cardiovascular parameters on changes in local skin surface temperature (SST) during gradual cooling and heating. Results showed that local SST changes affected the Finometer BP, the PPG waveforms and total peripheral resistance, but not oscillometric BP, heart rate, stroke volume and cardiac output. Therefore, in order to reduce for the errors, temperatures should be controlled or compensated when components of the PPG waveform are used to evaluate cardiovascular status in temperature variation environments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.12
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• pp.1829-1836
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• 2010

The district heating system distributes the heat generated from a cogeneration plant to wider locations. In this process, the district heating pipe (DHP) is subjected to internal and external loadings. The internal loadings are generally caused by the operating conditions such as water temperature and internal pressure. Frictional interactions between the pipes and the soil contribute to the external loadings. Thus, investigation of the mechanisms of failure of DHPs will help to guarantee both mechanical stability and heating efficiency. In this study, we investigate the local buckling of DHPs using limit state design (LSD). Two methods are considered: the use of the limit state for the width-thickness ratio and the use of the limit state for the strain. The results are used to confirm that the DHP is stable under local buckling. Finally, we suggest a minimum preheating temperature for avoiding local buckling.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.89-91
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• 2022

Wireless sensor networks(WSN), which are mainly used for indoor positioning, rely on the accuracy of RSSI. This RSSI is sensitive to several factors that cause interference, and there are foreign studies showing that temperature has a large effect on RSSI in indoor/outdoor environment among several factors. The temperature of the indoor space is uneven due to heat sources or air cooling systems indoors, and temperature changes frequently occur at certain locations. In particular, in case of an indoor fire, the accurate positioning system is required to guide an evacuation route, but a high temperature is locally formed due to a fire around the receiver, so the RSSI value could be influenced. In this paper, the effect on RSSI is studied by analyzing the correlation between SoC internal/local temperature and RSSI.

• Analytical Science and Technology
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• v.11 no.3
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• pp.202-205
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• 1998

X-ray absorption fine structure spectroscopic studies at the Ni K-edge have been performed for the Ni-Zn alloy coating layer on steel. The Ni-Zn interatomic distances and Debye-Waller factors were determined by fitting the experimental data with the theoretical spectra in the temperature range of 80 to 300K. The average Ni-Zn interatomic distance was found to be $2.557{\AA}$ and the variation of the Ni-Zn interatomic distance with temperature in this range was insignificant. From the comparison of the Ni-Zn interatomic distance with the nearest neighbor distance of pure Zn lattice it has been suggested that there is an apparent contraction around Ni atom.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.11
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• pp.45-52
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• 2005

In this paper, we propose the PLL system of the local oscillator system for the millimeter wave band's radio astronomy receiving system. The development of the proposed local oscillator system based on the YIG oscillator VCO with $26.5\~40GHz$ specification. This system consists of the oscillator part including the YIG VCO, the harmonic mixer, and the isolator, the RF processing part including the triplexer, limiter, and RF discrimination processor, and the PLL system including YIG modulator and controller. Based on this configuration, we verify the frequency and power stability of the developed local oscillator system according to some temperature variation. From this test results we confirm the stable output frequency and power characteristic peformance of the developed LO system at constant temperature.