• Title/Summary/Keyword: stress indices

Search Result 345, Processing Time 0.029 seconds

Stress Index Development for Piping with Trunnion Attachment Under Pressure and Moment Loadings

  • Lee, Dae-hee;Kim, Jong-Min;Park, Sung-ho
    • Nuclear Engineering and Technology
    • /
    • v.29 no.4
    • /
    • pp.310-319
    • /
    • 1997
  • A finite element analysis of a trunnion pipe anchor is presented. The structure is analyzed for the case of internal pressure and moment loadings. The stress results are categorized into the average (membrane) stress, the linearly varying (bending) stress and the peak stress through the thickness. The resulting stresses are interpreted per Section III of the ASME Boiler and Pressure Vessel Code from which the Primary(B$_1$), Secondary(C$_1$) and Peak(K$_1$) stress indices for pressure, the Primary (B$_2$), Secondary(C$_2$) and Peak(K$_2$) stress indices for moment are developed. Based on the comparison between stress value by stress indices derived in this paper and stress value represented by the ASME Code Case N-391-1, the empirical equations for stress indices are effectively used in the piping stress analysis. Therefore, the use of empirical equations can simplify the procedure of evaluating the local stress in the piping design stage.

  • PDF

Comparison of Several Heat Stress Indices for the 2016 Heat Wave in Daegu (대구의 2016년 폭염시기 열 스트레스 지표의 비교)

  • Kim, Ji-Hye;Kim, Hae-Dong
    • Journal of Environmental Science International
    • /
    • v.26 no.12
    • /
    • pp.1399-1405
    • /
    • 2017
  • We compared the spatial distribution of several heat stress indices (the Wet-Bulb Globe Temperature(WBGT) index, Environmental Stress Index (ESI), and Modified Discomfort Index(MDI)) for the heat wave of June 6~August 26, 2016, in Daegu. We calculated the heat stress indices using data from the high density urban climate observation network in Daegu. The observation system was established in February. 2013. We used data from a total of 38 air temperature observation points (23 thermometers and 18 automatic weather stations). The values of the heat stress indices indicated that the danger level was very high from 0900-2000h in downtown Daegu. The daily maximum value of the WBGT was greater than or equal to $35^{\circ}C$. The differences in the heat stress indices from downtown and rural areas were higher in the daytime than at nighttime. The maximum difference was about 4 before and after 1400h, and the time variations of the heat stress indices corresponded well. Thus, we were able to confirm that the ESI and MDI can be substituted with the WBGT index.

Development of Stress Indices for Trunnion Pipe Support (원통형 배관 지지대의 응력계수 개발)

  • 김종민;박명규;엄세윤;이대희;박준수
    • Computational Structural Engineering
    • /
    • v.9 no.3
    • /
    • pp.115-123
    • /
    • 1996
  • A finite element analysis of a trunnion pipe anchor is presented. The structure is analyzed for the case of internal pressure and moment loadings. The stress results are categorized into the average (membrance) and the linearly varying(bending) stresses through the thickness. The resulting stresses are interpreted per Section III of the ASME Boiler and Pressure Vessel Code from which the Primary (B/sub 1/) and Secondary(C/sub 1/) stress indices for pressure, the Primary(B/sub 2R/, B/sub 2T/) and Secondary(C/sub 2R/, C/sub 2T/) stress indices for moment are developed. Several analyses were performed for various structural geometries in order to obtain empirical representation for the stress indices in terms of dimensionless ratios.

  • PDF

Heat Stress Assessment and the Establishment of a Forecast System to Provide Thermophysiological Indices for Harbor Workers in Summer (하계 항만열환경정보 제공을 위한 열환경 평가 및 예보시스템 구축)

  • Hwang, Mi-Kyoung;Yun, Jinah;Kim, Hyunsu;Kim, Young-Jun;Lim, Yeon-Ju;Lee, Young-Mi;Kim, Youngnam;Yoon, Euikyung;Kim, Yoo-Keun
    • Journal of Environmental Health Sciences
    • /
    • v.42 no.2
    • /
    • pp.92-101
    • /
    • 2016
  • Objectives: Outdoor workers are exposed to thermally stressful work environments. In this study, heat stress indices for harbor workers in summer were calculated to evaluate thermal comfort based on a human heat balance model. These indices are Physiological Subjective Temperature (PST), Dehydration Risk (DhR), and Overheating Risk (OhR) according to respective stage of cargo work in a harbor. In addition, we constructed a forecast system to provide heat stress information. Methods: Thermophysiological indices in this study were calculated using the MENEX model (i.e. the human heat balance model), which used as inputs the meteorological parameters, clothing insulation, and metabolic rate for each stage of cargo work in the harbor of Masan over the course of seven days, including a four-day heat wave. The forecast heat stress information constructed for Masan harbor was based on meteorological data supported by the Dong-Nae Forecast from the KMA (Korea Metrological Administration) and other input parameters. Results: According to higher metabolic rate, thermophysiological indices showed a critical level. In particular, PST was evaluated as reaching the 'Very hot' or 'Hot' level during all seven days, despite the heat occurring over only four. It is important in a regard to consider the work environment conditions (i.e. labor intensity and clothing in harbor). On a webpage, the forecast thermophysiological indices show as infographics to be easily understand. This webpage is comprised of indices for both current conditions and the forecast, with brief guidance. Conclusion: Thermophysiological indices show the risk level to health during a heat wave period. Heat stress information could help to protect the health of harbor workers. Further, this study could extend the applicability of these indices to a variety of outdoor workers in consideration of work environments.

A Study on the Reliability of the Occupational Job Stress Indices Questionnaire Applied to Koreans (Occupational Job Stress Index의 신뢰성(信賴性) 관(關)한 연구(硏究))

  • Lee, Young-Soo
    • Journal of Preventive Medicine and Public Health
    • /
    • v.13 no.1
    • /
    • pp.19-25
    • /
    • 1980
  • The Occupational Job Stress Indicies Questionnaire is a selfadministered instrument consisting of 48 questions which are designed to collect the perceived Job stress about individual. This questionnaire was translated into Korean and applied to the selected groups of 300 blue collar workers musical manufacture industy for the purpose of assessing the it's reliability from April 1. to July 30, 1980. The results obtained were as follows; 1. The range of reliability coefficients for all indices was. 45-.75 which was lower than .54-.87 of original. 2. The inter-item correlation matrix for all items comprising an index along with the intercorrelation of these items with the items comprising closely related indices. 3. The reliability of JOB SATISFACTION, INTRINSIC REWARDS and IMPORTANCE REWARDS revealed .14-.20 lower than that of original. On the point of view, some items should be adjusted in parallel with acutual situation of Korea through making a cultural comparative study and item factor analysis.

  • PDF

Detection of Drought Stress in Soybean Plants using RGB-based Vegetation Indices (RGB 작물 생육지수를 활용한 콩 한발 스트레스 판별기술 평가)

  • Sang, Wan-Gyu;Kim, Jun-Hwan;Baek, Jae-Kyeong;Kwon, Dongwon;Ban, Ho-Young;Cho, Jung-Il;Seo, Myung-Chul
    • Korean Journal of Agricultural and Forest Meteorology
    • /
    • v.23 no.4
    • /
    • pp.340-348
    • /
    • 2021
  • Continuous monitoring of RGB (Red, Green, Blue) vegetation indices is important to apply remote sensing technology for the estimation of crop growth. In this study, we evaluated the performance of eight vegetation indices derived from soybean RGB images with various agronomic parameters under drought stress condition. Drought stress influenced the behavior of various RGB vegetation indices related soybean canopy architecture and leaf color. In particular, reported vegetation indices such as ExGR (Excessive green index minus excess red index), Ipca (Principal Component Analysis Index), NGRDI (Normalized Green Red Difference Index), VARI (Visible Atmospherically Resistance Index), SAVI (Soil Adjusted Vegetation Index) were effective tools in obtaining canopy coverage and leaf chlorophyll content in soybean field. In addition, the RGB vegetation indices related to leaf color responded more sensitively to drought stress than those related to canopy coverage. The PLS-DA (Partial Squares-Discriminant Analysis) results showed that the separation of RGB vegetation indices was distinct by drought stress. The results, yet preliminary, display the potential of applying vegetation indices based on RGB images as a tool for monitoring crop environmental stress.

Evaluation of Erythrocyte Morphometric Indices in Juvenile Red Spotted Grouper, Epinephelus akaara under Elevated Water Temperature

  • Rahman, Md Mofizur;Baek, Hea Ja
    • Development and Reproduction
    • /
    • v.23 no.4
    • /
    • pp.345-353
    • /
    • 2019
  • Higher thermal exposure can influence the blood cell morphology and count. Hence, based on the previous results (Rahman et al., 2019), the present study evaluated the morphometric indices of erythrocytes and their nucleus under different water temperatures (25℃, 28℃, 31℃, and 34℃) to investigate their use as an indicator of thermal stress in red spotted grouper, Epinephelus akaara. 180 healthy specimens of E. akaara were exposed to four temperature conditions (25℃ as control, 28℃, 31℃, and 34℃) for 42 days, following 2 weeks of acclimation at 25℃. Erythrocyte major axis (EL), erythrocyte minor axis (EW), nucleus major axis (NL), and nucleus minor axis (NW) were examined from the blood smears on each sampling day (i.e., 2, 7, and 42 days of thermal exposure). EL and NL were significantly decreased, whereas EW and NW were increased at higher water temperature (31℃ and 34℃). The major-minor axis proportions of erythrocytes and their nucleus (EL/EW; NL/NW) were decreased with increasing water temperature (31℃ and 34℃). The strong relationships were observed among the morphometric indices of erythrocytes and their nucleus, especially in EL vs. NL and EW vs. NW. This study reveals that elevated water temperature (31℃ and 34℃) can influence the major and minor axis morphometry of erythrocytes and their nucleus in red spotted grouper. These indices may be used as stress indicators to monitor the health status of E. akaara and probably for other fish species.

Transient microfluidic approach to the investigation of erythrocyte aggregation: comparison and validation of the method

  • Hou, Jian-Xun;Shin, Se-Hyun
    • Korea-Australia Rheology Journal
    • /
    • v.20 no.4
    • /
    • pp.253-260
    • /
    • 2008
  • A method based on transient shear flow dynamics of red cell aggregates was developed to investigate reversible re-aggregation processes with decreasing shear flow. In the microchannel-flow aggregometry, the aggregated red blood cells that are subjected to continuously decreasing shear stress in microchannel flow were measured with the use of a laser-scattering technique. Both the laser-backscattered intensity and pressure were simultaneously measured with respect to time, resulting in shear stress ranging from $0{\sim}35\;Pa$ for a time period of less than 30 seconds. The time dependent recording of the backscattered light intensity (syllectogram) yielded an upward convex curve with a peak point, which reflected the transition threshold of aggregation in the RBC suspensions. Critical-time and critical-shear stress corresponding to the peak point were examined by varying the initial pressure-differential and the micro channel depth, and these results showed good potential for being used as new aggregation indices. In the present study, these newly proposed indices were also validated by differentiating the effect of fibrinogen on RBC aggregation and then these indices were compared to the conventional indices that were measured by a rotational aggregometer.

Stress Indices of Hollow Circular Cross Section Welded Attachments on Piping Elbows with the Extended Parameters Range (매개변수 적용범위를 확장한 배관 곡관부에 용접 부착된 원형관 이음부의 이차응력지수)

  • Lee, Kun-Suk;Moon, Seong-Jae
    • Plant Journal
    • /
    • v.15 no.4
    • /
    • pp.43-51
    • /
    • 2019
  • The stress concentration of the integral welded attachments (IWA) often used to support piping system has been a big issue because it induces local stresses in piping. The method to evaluate local stresses associated with attachments on elbows has been suggested in EPRI TR-107453. However, there are limitations regarding specific parameters range in order to use correlation equation. In this paper, parametric study based on piping elbow size and attachment dimension was performed utilizing finite element analysis (FEA) to evaluate the secondary stress indices of hollow circular cross section welded attachments on piping elbows with the extended parameters range. The results of the FEA were used to develop correlation formulas for calculating secondary stress indices. The empirical equations in this study are suggested as an alternative evaluation method of EPRI TR-107453 by extending parameters range.

Evaluation of Thermal and Water Stress on Vegetation from Satellite Imagery

  • Viau, Alain A.;Jang, Jae-Dong;Anctil, Francois
    • Proceedings of the KSRS Conference
    • /
    • 2003.11a
    • /
    • pp.165-167
    • /
    • 2003
  • To evaluate the thermal and water stress of vegetation canopy in Southern Qu$\'{e}$bec, leaf water status was evaluated from vegetation indices derived from SPOT VEGETATION images and surface temperature from NOAA AVHRR images. This study was conducted by investigating vegetation conditions for two different periods, from June to August, 1999 and 2000. The vegetation indices were integrated for the evaluating vegetation conditions as a new index, normalized moisture index (NMI). A trapezoid was defined by the NMI and surface temperature, and the thermal and water status of the vegetation canopy was determined according to separate small sections within the trapezoid.

  • PDF