• Title/Summary/Keyword: temperature variations

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Stress variation analysis based on temperature measurements at Zhuhai Opera House

  • Lu, Wei;Teng, Jun;Qiu, Lihang;Huang, Kai
    • Structural Monitoring and Maintenance
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    • v.5 no.1
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    • pp.1-13
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    • 2018
  • The Zhuhai Opera House has an external structure consisting of a type of spatial steel, where the stress of steel elements varies with the ambient temperature. A structural health monitoring system was implemented at Zhuhai Opera House, and the temperatures and stresses of the structures were monitored in real time. The relationship between the stress distribution and temperature variations was analysed by measuring the temperature and stresses of the steel elements. In addition to measurements of the structure stresses and temperatures, further simulation analysis was carried out to provide the detailed relationship between the stress distributions and temperature variations. The limited temperature measurements were used to simulate the structure temperature distribution, and the stress distributions of all steel elements of the structure were analysed by building a finite element model of the Zhuhai Opera House spatial steel structure. This study aims to reveal the stress distributions of steel elements in a real-world project based on temperature variations, and to supply a basic database for the optimal construction time of a spatial steel structure. This will not only provide convenient, rapid and safe early warnings and decision-making for the spatial steel structure construction and operation processes, but also improve the structural safety and construction accuracy of steel space structures.

Effects of thickness variations on the thermal elastoplastic behavior of annular discs

  • Wang, Yun-Che;Alexandrov, Sergei;Jeng, Yeau-Ren
    • Structural Engineering and Mechanics
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    • v.47 no.6
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    • pp.839-856
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    • 2013
  • Metallic annular discs with their outer boundary fully constrained are studied with newly derived semi-analytical solutions for the effects of thickness variations under thermal loading and unloading. The plane stress and axisymmetric assumptions were adopted, and the thickness of the disk depends on the radius hyperbolically with an exponent n. Furthermore, it is assumed that the stress state is two dimensional and temperature is uniform in the domain. The solutions include the elastic, elastic-plastic and plastic-collapse behavior, depending on the values of temperature. The von Mises type yield criterion is adopted in this work. The material properties, Young's modulus, yield stress and thermal expansion coefficient, are assumed temperature dependent, while the Poisson's ratio is assumed to be temperature independent. It is found that for any n values, if the normalized hole radius a greater than 0.6, the normalized temperature difference between the elastically reversible temperature and plastic collapse temperature is a monotonically decreasing function of inner radius. For small holes, the n values have strong effects on the normalized temperature difference. Furthermore, it is shown that thickness variations may have stronger effects on the strain distributions when temperature-dependent material properties are considered.

SL/SST variations and their Correlations in the North East Asian Seas by Remote Sensing

  • Yoon, Hong-Joo
    • Journal of information and communication convergence engineering
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    • v.1 no.1
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    • pp.58-60
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    • 2003
  • Altimeter(Topex/Poseidon) and AVHRR(NOAA) data were used to study the variations and correlations of Sea Level(SL) and Sea Surface Temperature (SST) in the North East Asian Seas from November 1993 to May 1998. This region is influenced simultaneously to continental and oceanic climate. SL and SST have increased gradually every year because the global warming, and presented usually a strong annual variations in Kuroshio extension region with the influence of bottom topography.

Relationship between Sea Surface Temperature and Air Temperature Variation Depend on Time Scale at Coastal Stations in Korea (시간스케일에 따른 해양표면수온과 기온의 변동 및 상관연구)

  • 장이현;강용균;서영상
    • Journal of Environmental Science International
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    • v.9 no.4
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    • pp.303-309
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    • 2000
  • The relationship between air temperature and sea surface temperature and studied using the daily air temperature and sea surface temperature data for 25 years (1970~1994) at 9 coastal stations in Korea. Seasonal variations of air temperature have larger amplitudes than those of sea surface temperature. The seasonal variations of air temperature leads those of sea surface temperature by 2 to 3 weeks. The anomalies of sea surface temperature and air temperature with time scales more than 1 month are more ghighly correlated than those of short term, with time scales less than 1 month. Accumulated monthly anomalies of sea surface temperature and air temperature for 6 months shwoed higher correlation than the anomailes of each month. The magnitudes of sea surface temperature and air temperature anomalies are related with the duration of anomalies. Their magnitudes are large when the durations of anomalies are long.

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Concrete Lining Behaviors of Subway Tunnels according to Temperature Variations (온도변화에 따른 지하철 터널의 콘크리트 라이닝 거동)

  • Yoo, Ji-Hyeung;Lee, Seung-Won;Kim, Dae-Sung
    • Journal of the Korean Society for Railway
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    • v.17 no.6
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    • pp.410-414
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    • 2014
  • In this study, the behavior of urban subway tunnels is measured using instrumentation sensors installed in the lining concrete inside subway tunnels in order to analyze their behavior according to temperature variations. It is observed that the stresses of the concrete lining, tunnel convergence, and cracks change according to the temperature variations. However, the crack deformation differs depending on the size and status of the crack. In addition, this study proposes a correction formula for the lining stress and tunnel convergence through numerical analyses of the concrete lining according to the temperature variations. The results of this research can be used in the tunnel maintenance considering the tunnel behavior depending on the temperature variations in the tunnel.

Statistical Models of Air Temperatures in Seoul (서울시 도시기온 변화에 관한 모델 연구)

  • 김학열;김운수
    • Journal of the Korean Institute of Landscape Architecture
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    • v.31 no.3
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    • pp.74-82
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    • 2003
  • Under the assumption that the temperature of one location is closely related to land use characteristics around that location, this study is carried out to assess the impact of urban land use patterns on air temperature. In order to investigate the relationship, GIS techniques and statistical analyses are utilized, after spatially connecting urban land use data in Seoul Metropolitan Area with atmospheric data observed at Automatic Weather Stations (AWS). The research method is as follows: (1) To find out important land use factors on temperature, simple linear regressions for a specific time period (pilot study) are conducted with urban land use characteristics, (2) To make a final model, multiple regressions are carried out with those factors and, (3) To verify that the final model could be appled to explain temperature variations beyond the period, the model is extensively used for 5 different time periods: 1999 as a whole; summer in 1999; 1998 as a whole; summer in 1998; August in 1998. The results of simple linear regression models in the pilot study show that transportation facilities and open space area are very influential on urban air temperature variations, which explain 66 and 61 percent of the variations, respectively. However, the other land use variables (residential, commercial, and mixed land use) are found to have weak or insignificant relationship to the air temperatures. Multiple linear regression with the two important variables in the pilot study is estimated, which shows that the model explains 75 percent of the variability in air temperatures with correct signs of regression coefficients. Thus, it is empirically shown that an increase in open space and a decrease in transportation facilities area can leads to the decrease in air temperature. After the final model is extensively applied to the 5 different time periods, the estimated models explain 68 ∼ 75 percent of the variations in the temperatures is significant regression coefficients for all explanatory variables. This result provides a possibility that one air temperature model for a specific time period could be a good model for other time periods near to the period. The important implications of this result to lessen high air temperature we: (1) to expand and to conserve open space and (2) to control transportation-related factors such as transportation facilities area, road pavement and traffic congestion.

A Study on Performance of PEMFC with Variations on Stack Temperature and Mass Flow Rate (스택온도 및 유량변화에 따른 PEMFC의 출력특성 연구)

  • Park, Se-Joon;Choi, Yong-Sung;Lee, Kyung-Sup
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.11a
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    • pp.140-140
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    • 2009
  • The polymer electrolyte membrane fuel cell(PEMFC) with the advantages of low-operating temperature, high current density, low cost and volume, fast start-up ability, and suitability for discontinuous operation becomes the most reasonable and attractive power system for transportation vehicle and micro-grid power plant in a household. 200W PEM-type FCs system was integrated by this study, then the electrical characteristics and diagnosis of the fuel cell were analyzed with variations on mass flow rate and stack temperature. The ranges of the variations are $20{\sim}70^{\circ}C$ on stack temperature and 1~8L/min on $H_2$ volume.

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Structural Behavior of Concrete Pavement Due to Temperature Variations (온도변화에 의한 콘크리트 포장도로의 구조 거동 연구)

  • 조병완
    • Computational Structural Engineering
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    • v.4 no.2
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    • pp.95-102
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    • 1991
  • Some sections of concrete highway pavements have been viewed with great concern by highway officials and engineers due to the severe cracking and failure problems. This is mainly due to the traffic loads in addition to temperature variations between top and bottom of concrete slab, which cause the concrete slab to curl up and down depending on the thermal gradient, respectively. Subsequently, a major consideration was given to the derivation of stiffness matrix and equivalent nodal loads due to the uniform gravity load, temperature and shrinkage of concrete. And the structural behavior of concrete highway pavement due to the temperature variations throughout the nations has been emphasized.

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Optical Design of a Laser Scanning System Stable Against Wavelength and Temperature Variations (파장과 온도변화에 안정한 레이저 주사광학계 설계)

  • Kim, Da Ae;Lee, Jong-Ung
    • Korean Journal of Optics and Photonics
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    • v.27 no.1
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    • pp.32-40
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    • 2016
  • The characteristics of an optical system vary depending on wavelength and ambient temperature. Based on the thin-lens approximation, we investigate the conditions for stabilizing an optical system against wavelength and temperature variations at the same time. The conditions are applied to designing a laser scanning system consisting of two lenses. The change in the effective focal length of the scanning system against wavelength and temperature variations is very small, as expected.

Occurrence of Modern Planktonic Foraminiferal Species and their Seasonal Variations around Jeju Island, Korea (제주근해에 출현하는 현생 부유성 유공충 종과 계절변화)

  • Hyun, Sangmin;Kimoto, Katsunori;Cho, Sung-Hwan
    • Ocean and Polar Research
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    • v.35 no.2
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    • pp.181-191
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    • 2013
  • To investigate the occurrence of modern living planktonic foraminiferal species and their seasonal variations around Jeju Island, we conducted planktonic foraminiferal sampling at KIOST's regular sampling sites during 16 months. In total seven genus and 16 modern planktonic foraminiferal species were identified with six dominant species. Dominant species were Gloigerinoides sacculifer, Globigerinoides ruber, Globigerina bulloides, Noegloboquadrina dutertrei, Pulleniatina obliquiloculata, and Globorotalia inflata. Most of the species were characterized as being typical subtropical species and showed seasonal variations and/or intermittent occurrence from season to season. The occurrence of living foraminifera revealed a strong relationship with water temperature, but not with salinity. Species succession seems to occur along with water temperature changes. Some patch distribution and water temperature dependences appear to be significant since there is a high degree of variation in the occurrence patterns of species and standing stock. More detailed quantitative study is necessary to confirm the species diversity and seasonal variations of planktonic foraminifera and related ocean environmental changes.