• 대한기계학회논문집A
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• 제25권11호
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• pp.1813-1819
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• 2001

Partial penetration welding Joint defines that groove welds without steel backing, welded from on side, and groove weeds welded from both sides but without back gouging, that is. it has an unwelded portion at the root of the weld. In this study we analysed fur residual stress and displacement distribution on partial penetration welding condition of thick plate metal. For 25.4mm thick plate, theoretical residual stress and displacement analysis by finite element method using ABAQUS was carried out and compared with the experimental result using hole-drilling method. In results of the condition of partial penetration, it appeared that longitudinal stress at welding area was a little difference and transverse stress did not have any effect by partial penetration multi-pass welding. From a point of welding distortion in partial penetration multi-pass welding, it seemed to be better to control root face smaller than 6.35mm.

• Journal of Advanced Marine Engineering and Technology
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• 제30권6호
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• pp.709-715
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• 2006

The effects of thermal cycle condition and applied stress on the intergranular corrosion in austenitic 316 type stainless steels were investigated. Specimens were solution-treated at 1100$^{\circ}C$ for one hour and then sensitized in the temperature range of $500{\sim}800^{\circ}C$ by holding $2{\sim}300s$ with a various applied stresses of $0{\sim}8kg/mm^2$. Degree of sensitization. DOS %, was measured through polarization curve by electrochemical DL-EPR test. Microstructural observations were also conducted DOS % increased with an increase of sensitization temperature and/or holding time. Increase of applied stress resulted in increase of DOS % and more corroded surface because of acceleration of intergranular corrosion and fine grain size due to the stress. Cr depleted zone near grain boundary was observed. The amount of depletion was profounded with an increase of sensitization temperature, holding time and applied stress. $M_{23}C_6$ carbides were precipitated discontinuously at grain boundary. However, its amount was relatively small in the thermal cycle condition of 800$^{\circ}C$, 300sec and 4kg/mm$^2$.

• 기본간호학회지
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• 제8권2호
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• pp.199-209
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• 2001

The purpose of this study was to examine the relationship between life stress and depression, and the effect of social support in postpartal $4{\sim}6$ week women. Theoretically social support is thought to mediate the relationship between life stress and depression. Data were collected from June 1 to July 30, 1999. The data were analysed by use of SPSS. Two hypotheses were tested using Gamma, a measure of association for ordinal variables. Partial gamma was used to test the third hypothesis. Patterns of elaboration described by Babbie(1986) were selected to interpret the relationship of the three variables in the analyses. The results of this study are summarized as follows ; There was a positive relationship between life stress and depression (Gamma=.45, P=.017), and an inverse relationship between social support and depression (Gamma=-.49, P=.009). Thus the first, two hypotheses were supported. 2. When social support was controlled, the relationship between life stress and depression increased under the condition of low social support, but with high social support, the relationship decreased. It can be interpreted that life stresses are positively related to depression under the condition of low social support, however this relationship cannot be expected with high social support.

• 한국안전학회지
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• 제21권6호
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• pp.7-13
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• 2006

A transient heat transfer and thermal stress analysis for a brake drum of commercial vehicles have been performed by ANSYS code in the cases of single braking and the repeated braking condition. The temperature and thermal stress distributions in the brake drum under various braking conditions were obtained using a two-dimensional axisymmetric model. In case of deceleration of 0.3G with an initial vehicle speed of 60km/h, the maximum temperature in the drum was $87.6^{\circ}C$ after braking application. The maximum stress of 78.7MPa in the drum occurred at the intersection between the flange and hat under a condition in which repeated 15 cycles braking with an initial vehicle speed of 60km/h and a deceleration of 0.3G is applied to according to KS R1129. The maximum stress value is much lower than the yield strength of drum material(FC250).

• KSBB Journal
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• 제11권1호
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• pp.52-57
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• 1996

평활근 세포에 대한 shear stress의 영향을 알아보기 위해 슬라이드 글라스위에 배양된 牛 대통맥의 평활근 세포를 120시간 동안 0~26 dyn/$cm^2$의 각기 다른 일정한 shear stress의 유체에 노출하였다. 실험 장치를 순환하는 배지의 lactate dehydrogen­a ase의 농도측정 결과, 본 연구에서 적용된 shear stress 범위에서는 유체의 흐름으로 인하여 세포가 슬라이드 글라스 표면으로부터 이탈되는 현상은 없었다. 표면 $cm^2$ 당 존재하는 세포의 수를 측정한 결과, 평활근 세포는 정체배양시 가장 빨리 성장하였다. 표변에서의 shear stress가 증가할수록 i영활근 세포의 성장은 늦었으며, shear stress가 17 dyn/$cm^2$ 이상에서는 세포의 성장이 관찰되지 않았다.

• 대한기계학회논문집A
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• 제37권10호
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• pp.1297-1303
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• 2013

자동차 조향장치의 볼 조인트의 더스트 커버의 밀봉성과 응력 평가를 위하여 비선형 요한요소해석을 수행하였다. 주름형상과 항아리형상의 두 종류의 더스트 커버에 대하여 조립상태와 작동상태에 대하여 해석을 수행하여, 최대응력과 리브에서의 접촉응력 결과를 평가하고 비교하였다. 또한 작동상태에서의 몸통부 응력과 리브의 접촉응력이 조립상태 대비 증가하는 정도를 평가하였다. 해석 결과로부터 두 종류 모두 밀봉성이 우수한 것으로 확인되었으나, 상대적으로 최대응력이 작은 주름형상이 항아리형상보다 더 우수한 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제22권5호
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• pp.563-574
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• 2006

This paper studies mechanical behavior of the superelastic shape memory alloy (SMA) rods in terms of local deformations and time via tensile loading-unloading cycles for both ends fixed end constraints. Besides the unique stress induced martensitic transformation (SIMT), SMA's time dependent behavior when it is in mixed-phase condition upon loading and unloading, also need careful attention with a view of investigating the local deformation of the structural elements made of the same material. With this perspective, the so-called stress-relaxation tests have been performed to demonstrate and investigate the local strains-total strains relationships with time, particularly, during the forward SIMT. Some remarkable phenomena have been observed pertaining to SIMT, which are absent in traditional materials and those unique phenomena have been explained qualitatively. For example, at the stopped loading conditions the two ends (fixed end and moving end of the tensile testing machine) were in fixed positions. So that there was no axial overall deformation of the specimen but some notable increase in the axial local deformation was shown by the extensometer placed at the middle of the SMA specimen. It should be noted that this peculiar behavior termed as 'inertia driven SIMT' occurs only when the loading was stopped at mixed phase condition. Besides this relaxation test for the SMA specimens, the same is performed for the mild steel (MS) specimens under similar test conditions. The MS specimens, however, show no unusual increase of local strains during the stress relaxation tests.

• 센서학회지
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• 제20권2호
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• pp.118-123
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• 2011

Heart related diseases mainly caused by heavy work load and increasing stress in human daily life. Therefore, researches on mobile healthcare monitoring for daily life has been carried out. Notably, wearable healthcare monitoring system which has least restriction has been tried to provide an emergency alert of abnormal heart rate. In this study, we developed chair type unconstrained BCG measurement system which able to perform continuous heart status monitoring at the office and daily life in the unconstrained way. Furthermore, adaptive threshold is used to detect the heart rate from BCG signals. The HRV(heart rate variability) is calculated from heart rate interval. ECG signal measured using conventional method and BCG signal measured using unconstraint system are carried out simultaneously for the purpose of performance evaluation. From the comparison result, BCG signal shows a similar heart beat characteristic as ECG signal. This proves the possibility of practical implementation of unconstraint healthcare monitoring system. In addition, medical examination like valsalva maneuver is performed to observe the changes in HRV due to stress. By performing valsalva maneuver, heart is said to be placed under an artificial physical stress condition. Under this artificial physical stress condition, the time and frequency domain of HRV parameters are evaluated.

• 한국자원식물학회지
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• 제21권3호
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• pp.210-215
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• 2008

Gene-expression analysis is increasingly important in biological research, with real-time reverse PCR (RTPCR) becoming the method of choice for high-throughput and accurate expression profiling of selected genes. However, this technique requires important preliminary work for standardizing and optimizing the many parameters involved in the analysis. Plant stress studies are more and more based on gene expression. The analysis of gene expression requires sensitive and reproducible measurements for specific mRNA sequence. Several genes are regulated in response to abitoic stresses, such as salinity, and their gene products function in stress response and tolerance. The design of the primers and TaqMan probes for real-time PCR assays were carried out using the Primer $Express^{TM}$ software 3.0. The PCR efficiency was estimated through the linear regression of the dilution curve. To understand the expression pattern of various genes under salt stressed condition, we have developed a unique public resource of 9 stress-related genes in poplar. In this study, real-time RT-PCR was used to quantify the transcript level of 10 genes (9 stress-related genes and 1 house keeping gene) that could play a role in adaptation of Populus davidiana. Real-time RT-PCR analyses exhibited different expression ratios of related genes. The data obtained showed that determination of mRNA levels could constitute a new approach to study the stress response of P. davidiana after adaptation during growth in salinity condition.

• Smart Structures and Systems
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• 제19권2호
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• pp.203-211
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• 2017

This paper provides a numerical solution for multiple confocal elliptic dissimilar cylinders. In the problem, the inner elliptic notch is under the traction free condition. The medium is composed of many confocal elliptic dissimilar cylinders. The transfer matrix method is used to study the continuity condition for the stress and displacement along the interfaces. Two cases, or the infinite matrix case and the finite matrix case, are studied in this paper. In the former case, the remote tension is applied in y- direction. In the latter case, the normal loading is applied along the exterior elliptic contour. For two cases, several numerical results are provided.