• Nuclear Engineering and Technology
• /
• 제55권4호
• /
• pp.1250-1264
• /
• 2023

This paper presents approximate in-depth residual stress and plastic strain profiles for laser-peened alloy 600 surface via FE analysis. In approximations, effects of the initial welding residual stress and the number of shots are quantified. Based on FE analysis results, residual stress profiles are quantified by two variables; the maximum difference in stress before and after LSP, and the depth up to which the compressive residual stress exists. Plastic strain profiles are quantified by one variable, the maximum equivalent plastic strain at the surface. The proposed profiles are validated by comparing with published LSP experimental results for welded plates. Effects of the initial welding residual stress and the number of shots on these variables are discussed. The proposed profile can be directly applied to predict the mitigation effect of LSP on PWSCC and to efficiently perform structural integrity assessment of laser peened nuclear components.

• 대한본초학회지
• /
• 제21권2호
• /
• pp.63-75
• /
• 2006

Objectives : We investigated the effects of Liriopis Tuber on the nervous protection. Methods : We measured the reaction behavior with EPM(Elevated Plus Maxe) and MWM(Morris Water Maze) after applying restraint stress to rats. Also, the degrees of AchE generation were measured with immunohistochemical method in the regions of hippocampus, and the degree of TH generation in the regions of VTA and LC, respectively. Results : 1. As the results of measuring how long EPM which reflects anxiety reaction stayed in the open arm, there was the trend which can suppress anxiety reaction in the MMD+stress group(Liriopis Tuber+stress) but no statistical significance. The counting results how many EPM passed between opened and closed arm showed suppression trend against a physical activity in the saline+stress group but there was no statistical significance. 2. According to the result of MWM, the saline+stress group showed the learning retardation which means increased time arriving at goal compared to ti1e normal group at the second and third day of measurement. On the contrary, a learning retardation was significantly decreased in the MMD+stress group. Among the probe trial test a memory loss occurred in the saline+stress group, meanwhile memory ability was notably increased in the saline-stress group. 3. The degree of TH generation was investigated at the VTA and LC respectively after test animals treated with drug. In the saline+stress group, TH-immunoreactive cells were significantly increased, and these stress-induced TH increases were suppressed in the saline+stress group at the VTA region. However, the saline+stress group did not show any significant difference. 4. the degree of AchE generation was investigated at the CA3 of hippocampus. The saline+stress group showed that AchE-immunoreactive cells were significantly decreased. Those stress-induced reductions of AchE cells were meaningfully recovered in the saline+stress group. Although the cells showed recovery trend in the region of CA1 of hippocampus, statistical significance was not observed. Conclusion : The results of our study indicate that Liriopis Tuber can improve spatial memory ability of rats applied a restraint stress. This improvement of the spatial memory ability is considered to have an efficacy of nervous protection that Liriopis Tuber suppresses the generation of AchE in the hippocampus region and enhances the generation of TH in the VTA.

• 한국CDE학회논문집
• /
• 제9권4호
• /
• pp.416-424
• /
• 2004

In this paper, the heat transfer analysis and thermal stress analysis of the PCB(Printed Circuit Board) equipped in electronic Packages are carried out for various may types of chips on the PCB. And two structural PCB models are used in the analyses. The electronic chips on the PCB usually emit heat and this heat generates the thermal stress around the chip. The thermal load due to the heat generation of chips on the PCB may cause the malfunction of the electronic packages such as a monitor. a computer etc. Hence, the PCB should be designed to withstand these thermal loads. In this paper, the heat transfer analysis and thermal stress analysis are executed for the PCB model with pins and the analysis results are compared with the results for the PCB model without pins. The analysis results show that the PCB model without pins is not good for the thermal stress analysis of PCB, even though these two models have similar heat transfer characteristics. The analysis results also show that the highest thermal stress occurs in the pin especially attached to the highest temperature chip, and the PCB constrained to the electronic package on the long side is structurally more stable than other cases. The analyses of the PCB are executed using the finite element analysis code, NISA.

• 대한기계학회논문집A
• /
• 제27권6호
• /
• pp.890-897
• /
• 2003

This paper compares engineering estimation schemes of C＊ and creep COD for circumferential and axial through-wall cracked pipes at elevated temperatures with detailed 3-D elastic-creep finite element results. Engineering estimation schemes included the GE/EPRI method, the reference stress method where reference stress is defined based on the plastic limit load and the enhanced reference stress method where the reference stress is defined based on the optimized reference load. Systematic investigations are made not only on the effect of creep-deformation behaviour on C＊ and creep COD, but also on effects of the crack location, the pipe geometry, the crack length and the loading mode. Comparison of the FE results with engineering estimations provides that for idealized power law creep, estimated C＊ and COD rate results from the GE/EPRI method agree best with FE results. For general creep-deformation laws where either primary or tertiary creep is important and thus the GE/EPRI method is hard to apply, on the other hand, the enhanced reference stress method provides more accurate and robust estimations for C* and COD rate than the reference stress method.

• 한국전산유체공학회지
• /
• 제6권4호
• /
• pp.35-42
• /
• 2001

In this study, numerical calculations are carried out in order to evaluate the performance of low-Re Reynolds stress model based on SSG model for a swirling turbulent flow in a pipe. The results are compared with those of k-ε model, GL model and the experimental data. The results show that low-Re Reynolds stress model and GL model give better results than k-ε model. In the region near the wall, low-Re Reynolds stress model improves the predictions. However, there is no large difference between the predictions with two Reynolds stress models.

• 한국기계가공학회지
• /
• 제10권3호
• /
• pp.73-78
• /
• 2011

This study contains to theory and analysis research for the stress and the translation of an expand disk that fix a ring gear for tooth profile machining. The stress of the expand disk is analysed by the finite element method(FEM) to calculate design parameters. From the analysis results, the stress of the expand shows a linear tendency under various fixing force. This results show that the expand disk have a elastic characteristics as a disk spring. The maximum stress was observed on under side in split section of the expand disk. It is verified that the analysis results are useful to calculate design parameters of the expand disk.

• Journal of Welding and Joining
• /
• 제8권3호
• /
• pp.79-88
• /
• 1990

Welded joint often contains soft or softened regions such as the HAZ of TMCP steel welded with high heat input. In this study, the equivalent yield strength of plate structure containing softened region was predicted by FEM analysis, and its incremental behavior was explained with the results of the analysis. The calculated results of yield strength indicated the following for the plate structures. 1) As the softened region starts to yield, shear stress begins to build up along the boundary between base metal and softened region. This results in multi-axial stress condition which gives restraint on the softened region. 2) Restraint effect has a significant influence on the distribution of the shear stress, the nominal stress, and the strain. 3) The yielding behavior of softened region becomes the same as that of base metal when both ratios of length to width and thickness to width of softened region are larger than 30 and 13 respectively.

• 가정과삶의질연구
• /
• 제19권2호
• /
• pp.143-152
• /
• 2001

The purpose of this study was to investigate the effects of family stress on work stress and to examine the effects of family and work stress on psychological wellbeing in employed men and women. The analyses of the present study were based on a sample of 263 full-time employed men and 258 full-time employed women aged 30-49 in dual-earner families. There were significant gender differences in marital stress, parenting stress and psychological well-being with women reporting higher levels of stress. However, employed men and women experienced similar levels of work stress. The results from regression analyses showed that stress in the family domain contributed significantly to work stress. Both marital stress and parenting stress were significantly related to higher levels of work stress fro employed men and women. The findings of this study indicated that higher levels of marital stress and work stress were predictive of psychological well-being for men and women in dual-earner couples. Among employed women, marital stress and work stress were more highly related to psychological well-being than among employed men.

• 한국화재소방학회논문지
• /
• 제21권2호
• /
• pp.74-86
• /
• 2007

본 연구는 소방공무원의 직무스트레스의 원인과 결과를 실증적으로 연구하기 위하여 구조모형을 개발하여 서울시소방방재본부에서 근무하는 961명을 대상으로 이를 검증하였다. 분석의 결과는 소방직무특성과 동료관계는 직무스트레스에 직접적인 영향을 미치며 조직몰입에도 직접적인 영향을 미치는 것으로 나타났다. 소방공무원의 역할혼돈은 직무스트레스에 직접적인 영향을 미치고 조직몰입에는 직무스트레스를 거쳐 간접적인 영향을 미치는 것으로 조사되었다. 아울러 직무스트레스는 조직몰입에 부(-)의 영향을 미치는 것으로 나타났다. 이러한 연구결과는 소방공무원의 직무스트레스 관리체계 확립의 필요성을 설명하는데 있어 기초 자료로 활용할 수 있을 것으로 보이며, 향후 소방조직의 혁신과정에서 선택해야 할 미래지향점을 정립하는데 사용될 수 있을 것이다.

• Journal of Mechanical Science and Technology
• /
• 제17권11호
• /
• pp.1674-1681
• /
• 2003

Photoelastic experiment has two significant problems. The first problem is manufacturing a model specimen for complicated shapes of structures. The second problem is residual stress contained in the photoelastic model material. In this paper, the stress optic law that can be effectively used on photoelastic model materials with residual stress is developed. By using the stress optic law as developed in this research, we can obtain good results in photoelastic experiments using model material in which residual stress is contained. It is assured that the stress optic law developed in this research is useful. Therefore, it is suggested that the stress optic law considering residual stress can be applied to the photoelastic experiment for the stress analysis of the composite materials or bi-materials in which the residual stress is easily contained.