• Journal of the Korean Geotechnical Society
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• v.15 no.1
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• pp.151-160
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• 1999

A series of laboratory tests for the marine clay sampled under the sea of Kwangyang bay have been conducted. The main types of tests are the general index property tests, the oedometer tests and the triaxial compression tests in both undrained(CIU) and drained(CID) conditions. The clayey samples, classified as CL, CH with natural water content of 38.3~84.6% and liquidity index of 0.71~0.98, are in the normally consolidated state with O.C.R. of 1.0l~l.60. The undrained stress path from CIU tests can be normalized with isotropic consolidation pressure$(p_0)$ and equal shear strain contour is linear passing through the origin in the (q, p) plot. The undrained shear strain is found to be the only function of the stress ratio($\eta$) and linear with intercept in the ($\varepsilon/\eta,\eta$) plot. The built-up pore pressure normalized with pc is also linear with respect to $\eta$. and its slope is defined by ´C´ as a pore pressure parameter. Equations to predict the undrained stress path and the shear strain are proposed. It is proved that the proposed equations give better agreements to the measured values than the Cam-clay theories. The failure points of the stress path are located on the same C.S.L. in (q, p) plot during both CIU and CID tests, which justifies the concept of critical state theory.

• Journal of the Korean Geotechnical Society
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• v.30 no.3
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• pp.47-58
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• 2014

To investigate the unsaturated characteristics of the tailings obtained from the waste dump at Imgi mine, matric suction and volumetric water content were measured in both drying and wetting processes using Automated Soil-Water Characteristics Curve Apparatus. Based on the measured result, Soil Water Characteristic Curves (SWCC) were estimated by van Genuchten model. According to the unsaturated soil classification method, the tailings of the waste dump correspond to clayey sand. As a result of Suction Stress Characteristic Curve (SSCC) by Lu and Likos model, SSCC has a shape of S which is similar to SWCC. The hysteresis phenomenon occurred in SSCCs, which means the suction stress of drying path is larger than that of wetting path in the same effective degree of saturation. The effective stress of unsaturated soil is equal to that of saturated soil when matric suction is less than Air Entry Value (AEV). However, the effective stress of unsaturated soil is larger than that of saturated soil when matic suction is more than AEV. Meanwhile, unsaturated hydraulic conductivity by van Genuchten model decreased with increasing matric suction, and the hydraulic conductivity of drying path is larger than that of wetting path.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.1
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• pp.20-26
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• 2007

In this study, fatigue strength of load-carrying cruciform fillet welded joints were evaluated using a new method proposed by Yamada, for geometric or structural stress in welded joint, that is, one-millimeter stress below the surface in the direction corresponding to the expected crack path. Validity of the method is verified by analyzing fatigue test results for load-carrying cruciform welded specimens has different size of weld toe radius, leg length and plate thickness reported in literature. Structural stress concentration factor for 1mm below the surface was calculated by finite element analysis for each specimen respectively. When compared to the basic fatigue resistance curve offered by BS7608, the one-millimeter stress method shows conservative evaluation for load-carrying cruciform fillet welded joints.

• Korean Journal of Child Studies
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• v.26 no.4
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• pp.55-70
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• 2005

The Teachers' Job Stress Scale(D'Arienzo, 1981) and the General Self-Efficacy Scale(Kim & Cho, 1996) were used to study 170 child care teachers. Data were analyzed by one-way ANOVA, Pearson's partial correlation, stepwise multiple regression(forward), path analysis, Internal consistency(Cronbach's $\alpha$), and factor analysis. Results showed that job stress was low for teachers of the national child care center, university graduates, higher salaried, and married teachers. Self-efficacy was high among teachers with more than 2 years experience, married status, and previous experience. Correlation between teacher's job stress and self-efficacy was -.19. Self-efficacy and demographic variables for job stress explained 8~22% of the variability. Self-efficacy intermediated between job stress and demographic variables. Monthly salary directly affected job stress.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1844-1853
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• 2001

In the present investigation, it was attempted to design the rolling pass schedule fur a clean steel of 0.1C-1.5Mn-0.25Si with the objective of the austenite grain refinement. As the method of approach, a coupled mathematical modeling technique was proposed which consists of a recrystallization model and a flow stress modes. The validity of the coupled model was examined through comparison with results of continuous and discontinuous compression tests at various temperatures, strains and strain rates. The coupled model was incorporated with the finite element method to set up a systematic design methodology far the rolling path schedule for austenite grain refinement. Two path schedules were obtained and discussed in the paper with regard to rolling path time, average grain size, grain size deviation in thickness, etc.

• Composites Research
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• v.13 no.2
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• pp.51-60
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• 2000

Filament wound pressure vessels have been studied for the efficient design tool to consider the variation of fiber angles through-the thickness direction. Filament winding patterns were simulated from semi-geodesic fiber path equation to calculate fiber path on arbitrary surface. Finite element analyses were performed considering fiber angle variation in longitudinal and thickness directions by ABAQUS. For the finite element modeling of the pressure tank, the 3-dimensional layered solid element was utilized. From the stress results of pressure tanks, maximum stress criterion in transverse direction was applied to modify material properties for failed region. In the end of each load increment, resultant layer stresses were compared with a failure criterion and properties were reduced to 1/10 for a failed layer. Results of progressive failure analysis were compared with two experimental data.

• Research in Community and Public Health Nursing
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• v.27 no.4
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• pp.399-409
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• 2016

Purpose: The purpose of this study was to analyze factors influencing health-related quality of life (HRQoL) among male adults. Methods: Participants were 196 male adults who were recruited from June to July 2016. Seven variables related to HRQoL including age, perceived stress, physical activities, problem drinking, social support, self-esteem, depression were measured. Data were analyzed using the SPSS/WIN 20.0 program and Amos 18.0 for descriptive statistics, Pearson correlation coefficients and path analysis. Results: The mean for HRQoL was 80.14. The path analysis showed that depression had the greatest direct effect on HRQoL. It was found that perceived stress had direct and total effects on HRQoL. It also mediated the paths of social support and self-esteem to HRQoL. These factors account for 68% of the total variance, and the fit indices of the model satisfied the criteria of fitness. Conclusion: The results indicate that these factors influencing HRQoL should be considered when developing programs to improve HRQoL for male adults.

• Journal of Korean Academy of Nursing
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• v.34 no.2
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• pp.333-343
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• 2004

Purpose: This study was designed to construct a structural model for symptom management of life of the patients with chronic fatigue. The hypothetical model was developed based on the literature review and Self-regulating Model. Method: Data were collected by questionnaires from 252 patients with chronic fatigue in the 8 community from December 2002 to April 2003 in Seoul. Data analysis was done with SAS for descriptive statistics and PC-LISREL Program for Covariance structural analysis. Result: The fit of the hypothetical model to the data was moderate, thus it was modified by excluding 4 path and including free parameters and 3 path to it The modified model with path showed a good fitness to the empirical data($x^2$=318.11, p=0.0, GFI=.98, AGFI=.98, NNFI=.95, RMSR=.03, RMSEA=.05). The symptoms of stress, self-efficacy, and present fatigue level were found to have significant direct effect on symptom management of the patients with chronic fatigue. The ways of coping, perceived stress, and fatigue symptom were found to have indirect effects on symptom management of the patients with chronic fatigue. Conclusion: The derived model is considered appropriate in explaining and predicting symptom management of the patients with chronic fatigue. Therefore, it can effectively be used as a reference model for further studies and suggested direction in nursing practice.

• The Journal of Korean Society for School & Community Health Education
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• v.22 no.1
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• pp.11-24
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• 2021

Objectives: The purpose of this study was to examine the Path modeling effect among depression, Post-Traumatic Stress Disorders (PTSD), resilience, and social support on the quality of life (QoL) of natural disaster victims. Methods: This is a cross-sectional study with 1,979 disaster victims' cases by using the 4th Disaster victims panel survey in Korea. Data were collected from october 2018 to december 2018 and analyzed using regression analysis and path way analysis. Results: Perceived health, depression, social support, PTSD, resilience, and QoL showed significant correlations. PTSD was directly affected by depression and QoL was affected by PTSD. Social support was directly affected by depression and resilience was also directly affected by depression. QoL was affected by social support and resilience. Conclusion: This analysis highlighted that the relation between lower depression and QoL was mediated by greater social support and resilience and lower degree of PTSD. These results suggest that community health interventions and education that incorporate social support and resilience may improve the quality of life of natural disaster victims.

• Structural Engineering and Mechanics
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• v.92 no.1
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• pp.99-110
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• 2024

The crack propagation path can be considered as a boundary problem in which the crack advances towards the interior of the domain. Consequently, this poses an optimization problem wherein the local crack-growth direction angle can be treated as a design variable. The advantage of this approach is that the continuous minimization of strain energy naturally leads to the mode I propagation path. Furthermore, this procedure does not rely on the precise characterization of the stress field at the crack tip and is independent of stress intensity factors. This paper proposes an algorithm based on internal point exploration as well as shape sensitivity optimization and strain energy minimization to determine the crack propagation direction. To implement this methodology, the algorithm utilizes a modeling GUI associated with an academic analysis program based on the Dual Boundary Elements Method and determines the propagation path by exploiting the elastic strain energy at points in the domain that are candidates to be included in the boundary. The sensitivity of the optimal solution is also assessed in the vicinity of the optimum point, ensuring the stability and robustness of the solution. The results obtained demonstrate that the proposed methodology accurately predicts the crack propagation direction in Mode I opening for a single crack (lateral and central). Furthermore, robust optimal solutions were achieved in all cases, indicating that the optimal solution was not highly sensitive to changes in the design variable in the vicinity of the optimal point.