• Journal of Welding and Joining
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• v.13 no.4
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• pp.155-162
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• 1995

Redistribution of residual stress and its effects during fatigue crack propagates from tensile residual stress region in weldment are investigated. Tests are performed by using welded CCT specimens of structual rolling steel (SS400) and it makes fatigue crack propagate from tensile residual stress region. For this study tension-tension loading type is selected by external loading condition and magnetizing stress indicator is used correctly to measure redistribution of residual stress according to fatigue crack growth and number of loading cycles. From this result, it is proved that redistribution of residual stress is mainly consist of residual stress released by fatigue crack growth. When fatigue crack propagates from tensile residual stress region residual stress are redistributed and it makes fatigue crack growth rate largely increase. Fatigue crack growth rate is low in case of redistributed residual stress compare with initial distributed residual stress.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2178-2188
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• 2006

The stress collapse in the formation of shear bands in elasto-thermo-viscoplatic materials is systematically studied within the framework of one-dimensional formulation via analytical and numerical methods. The elastic energy released in a domain is found to play an important role in the collapse behavior of shear localization. A non-dimensional parameter named the stability indicator is introduced to characterize the collapse behavior, with approximate forms of the incremental governing equations. The stability indicator offers useful information regarding the degree of severity of an abrupt change of deformations during the stress collapse. Numerical experiments are carried out to verify the stability indicator by varying material properties.

• Korean Journal of Occupational Health Nursing
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• v.8 no.2
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• pp.141-155
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• 1999

For the purpose of disclosing the mental health status as well as its stress factors of female workers in industry, a questionaire survey was carried out on 283 female workers, namely. 134 of a service industry(department store) in seoul and 149 of a manufacturing industry(food) in Kyunggi-do district from 24 to 29 January, 1994. The result were as follows : 1. The mean scores of poor mental health indicator showed no significant difference between service industry and manufacturing industry, while the mean scores of good mental health indicator showed a significant difference between those two industries. 2. The mean scores of work stress as social stress factors showed a significant difference between service industry and manufacturing industry. However, no significant difference was observed between the mean scores of personal stress factor between those two industries. 3. In general, the work stress factor was more significantly contributed by marital status, while the social stress as well as the personal stress factor were contributed more by monthly income. 4. The major contributing factor to the poor mental health was the personal stress factor in general, followed by the work stress factor. However, the weight of these two stress factors was reversed according to the type of industries.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.7
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• pp.2234-2245
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• 1996

In this study residual stress in weldment was considered about the effect on the fatigue propagation and about the effect of redistribution of residual stress. Then, fatigue tests were conducted by the center notched specimens machined with welded plate. The residual stress and its redistribution after the crack growth were measured by the magnetizing stress indicator and hole-drilling method. Fatigue crack propagation was estimated by the specimens having residual stress redistributed after the cracks growth and having the effects of crack closure. Crack growth rates were predicted and compared with experimental results. It had been found that the predicted crack propagation rates have a good agreement with experimental results when the redistribution of residual stress was considerd.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.4
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• pp.565-572
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• 2010

It is difficult to predict the accurate fatigue life of the ship structure because of load uncertainty and load redistribution at the ship structure members. As one of studies for accurate evaluation and prediction of fatigue life, it is a promising way to detect the crack previously by attaching the Fatigue Indicator Sensor (FIS) at the crack prediction region. In order to predict the fatigue life of the ship structure by using FIS, it is required to know previously the crack propagation characteristics according to pre-notch shapes. In this study, we obtained the stress distribution phase, stress concentration factors and stress intensity factor of various pre-notch shapes through FEA. Additionally, we conducted the fatigue test and obtained the characteristics of crack propagation according to the pre-notch shapes through comparison between the fatigue test and the FEA. Consequently, we classified the pre-notch shape into 3 categories: Long, Medium, and Short life type. On the basis of the numerical and experimental results, the FIS can be developed.

• The Journal of Korean Academic Society of Nursing Education
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• v.19 no.2
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• pp.172-182
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• 2013

Purpose: This study was conducted to describe stress, stress coping, and school adaptation according to Myers-Briggs type indicator(MBTI) personality type in freshmen nursing students. Methods: This study was a cross sectional survey and the data was collected from 267 freshmen nursing students by means of self reported questionnaires from March 3 to 30, 2012. Collected data were analyzed on SPSS win 18.0. Results: 16 personality types were all seen in this study participants. There were no significant differences in stress, stress coping, and school adaptation according to 4 functions and 4 temperaments of MBTI. Conclusion: Nursing students show various personality types and we need to understand their diversity and reflect it to a school curriculum or education program development. Further study is required to identify the effects of self-understanding program on stress management and school adaptation.

• Journal of Physiology & Pathology in Korean Medicine
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• v.28 no.6
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• pp.668-673
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• 2014

Cold and Heat pattern identification(CHPI) in traditional East Asian medicine(TEAM) is one of the major indicator to distinguish characteristics of disease and to determine treatment method. Basic parameters to determine CHPI include the pulse rate, respiration rate, and pulse power. Studies to associate physiological responses of human body by cold stress(CS) with CHPI in TEAM were rarely done so far. This study aims to explore the effects of cold stress on pulse signal via a feasibility study for three subjects and investigate some indices which can reflect autonomic nerve reaction(ANR). We measured radial pulse signals and respiration signal of the investigated subjects before the CS, during the CS which continues for 5 minutes, and immediately after the CS, respectively. Finally, we analyzed the pulse rate (P), respiration rate (R), pulse power, pulse depth, and pulse rate per respiration (P/R ratio). As a result, the P/R ratio showed a consistently decreasing tendency through the CS stimulation process, while other parameters behaved more complex and in subject-specific ways. It implies that, among candidate parameters, the P/R ratio is a simple but the most probable parameter that can be used as the ANR indicator. This result is also consistent with the theory in TEAM scripts, in which the P/R ratio is predicted to be a direct indicator for the CHPI. This pilot study shows that P/R ratio can be more appropriately associated with the ANR than heart rate or respiration rate alone. Extensive studies will be necessary to verify or confirm the P/R ratio as an appropriate and well defined parameter for ANR.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.499-504
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• 2015

Decision making by farmers regarding irrigation is critical for crop production. Therefore, the precision irrigation technique is very important to improve crop quality and yield. Recently, much attention has been given to remote sensing of crop canopy temperature as a crop water-stress indicator, because it is a scientifically based and easily applicable method even at field scales. This study monitored a series of time-variant canopy temperature of cucumber under three different irrigation treatments: under-irrigation (control), optimal-irrigation, and over-irrigation. The difference between canopy temperature ($T_c$) and air temperature ($T_a$), $T_c-T_a$, was calculated as an indicator of cucumber water stress. Vapor pressure deficit (VPD) was evaluated to define water stress on the basis of the temperature difference between leaf and air. The values of $T_c-T_a$ was negatively related to VPD; further, cucumber growth in the under- and over-irrigated fields showed water stress, in contrast to that grown in the optimally irrigated field. Thus, thermal infrared measurements could be useful for evaluating crop water status and play an important role in irrigation scheduling of agricultural crops.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.5
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• pp.321-327
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• 2006

In Korea, there is a growing competitive for water resources between industrial, domestic and agricultural consumer, and the environment as many other OECD countries. The demand on water use is also affecting aquatic ecosystems particularly where withdrawals are in excess of minimum environmental needs for rivers, lakes and wetland habits. OECD developed three indicators related to water use by the agriculture in above contexts : the first is a water use intensity indicator, which is expressed as the quantity or share of agricultural water use in total national water utilization; the second is a water stress indicator, which is expressed as the proportion of rivers (in length) subject to diversion or regulation for irrigation without reserving a minimum of limiting reference flow; and the third is a water use efficiency indicator designated as the technical and the economic efficiency. These indicators have different meanings in the aspect of water resource conservation and sustainable water use. So, it will be more significant that the indicators should reflect the intrinsic meanings of them. The problem is that the aspect of an overall water flow in the agro-ecosystem and recycling of water use not considered in the assessment of agricultural water use needed for calculation of these water use indicators. Namely, regional or meteorological characteristics and site-specific farming practices were not considered in the calculation of these indicators. In this paper, we tried to calculate water use indicators suggested in OECD and to modify some other indicators considering our situation because water use pattern and water cycling in Korea where paddy rice farming is dominant in the monsoon region are quite different from those of semi-arid regions. In the calculation of water use intensity, we excluded the amount of water restored through the ground from the total agricultural water use because a large amount of water supplied to the farm was discharged into the stream or the ground water. The resultant water use intensity was 22.9% in 2001. As for water stress indicator, Korea has not defined nor monitored reference levels of minimum flow rate for rivers subject to diversion of water for irrigation. So, we calculated the water stress indicator in a different way from OECD method. The water stress indicator was calculated using data on the degree of water storage in agricultural water reservoirs because 87% of water for irrigation was taken from the agricultural water reservoirs. Water use technical efficiency was calculated as the reverse of the ratio of irrigation water to a standard water requirement of the paddy rice. The efficiency in 2001 was better than in 1990 and 1998. As for the economic efficiency for water use, we think that there are a lot of things to be taken into considerations to make a useful indicator to reflect socio-economic values of agricultural products resulted from the water use. Conclusively, site-specific, regional or meteorogical characteristics as in Korea were not considered in the calculation of water use indicators by methods suggested in OECD(Volume 3, 2001). So, it is needed to develop a new indicators for the indicators to be more widely applicable in the world.

• Journal of the Korean Wood Science and Technology
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• v.31 no.3
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• pp.35-41
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• 2003

The mechanical and physical properties of wood are strongly dependent upon the slope of grain. Specially, tensile strength is more severely affected by the slope of grain. Therefore, tension tests were performed on small thin wood samples made from Pinus radiata with varying the slope of grain. Determining the tensile strength for clear thin wood samples the other variabilities associated with material, size, drying, defects, etc were discarded. Slope of grain was measured by the slope of grain indicator and actual slope of grain was also determined by a protractor. Correlation coefficients between machine measured and actual slope of grain for 40 pieces of 2×20 mm, 300 mm long Pinus radiata were 0.84 for wide face measurement. Results also showed that tensile strength and MOE from stress wave tests decreased with increasing the slope of grain. This study did not establish a relationships for tensile strength and MOE from stress wave with slope of grain. However, the trends of MOEs from stress wave test with both slope of grain are agreed well with Hankinson's equation. Predicted tension strength curve by Hankinson's equation was also agreed well with the experimental data over the range from 0 to 13 degrees for slope of grain.