• Journal of Preventive Medicine and Public Health
• /
• v.29 no.2 s.53
• /
• pp.255-264
• /
• 1996

To study reliability and validity of PWI, this newly developed self-administered questionnaire which measures stress, was given to medical students. All respondent(133) were followed 4 weeks later and 92 were retested. Cronbach's $\alpha$ coefficient of data was 0.93. Test-retest reliability measured by Pearson's correlation coefficient was 0.72(P<0.01). Exploratory factor analysis(EFA) performed by principal axis factor method without iteration and by varimax rotation explored 13 principal components(eigenvalues > 1). After exploring 4 factor structure according to previous study results, factor 1 showed good agreement but other factors did not. Confirmatory factor analysis(CFA) showed poor fit of 4 factor model to data. In the further study, it may be considered to model that has unidimensional factor structure.

• Journal of Korean Neurosurgical Society
• /
• v.53 no.6
• /
• pp.331-336
• /
• 2013

Objective : The offset connector can allow medial and lateral variability and facilitate intralaminar screw incorporation into the construct. The aim of this study was to compare the biomechanical characteristics of C7 intralaminar screw constructs with and without offset connector using a three dimensional finite element model of a C6-7 cervical spine segment. Methods : Finite element models representing C7 intralaminar screw constructs with and without the offset connector were developed. Range of motion (ROM) and maximum von Mises stresses in the vertebra for the two techniques were compared under pure moments in flexion, extension, lateral bending and axial rotation. Results : ROM for intralaminar screw construct with offset connector was less than the construct without the offset connector in the three principal directions. The maximum von Misses stress was observed in the C7 vertebra around the pedicle in both constructs. Maximum von Mises stress in the construct without offset connector was found to be 12-30% higher than the corresponding stresses in the construct with offset connector in the three principal directions. Conclusion : This study demonstrated that the intralaminar screw fixation with offset connector is better than the construct without offset connector in terms of biomechanical stability. Construct with the offset connector reduces the ROM of C6-7 segment more significantly compared to the construct without the offset connector and causes lower stresses around the C7 pedicle-vertebral body complex.

• Geotechnical Engineering
• /
• v.9 no.4
• /
• pp.65-82
• /
• 1993

A series of torsion shear tests were performed to study the drained stress -strain behavior of medium dense Santa Monica Beach sand under various stress paths. The torque was applied to both clockwise and counterclockwise directions at the end of hollow cylinder specimen. Two clip gages had been previously used to measure the changes in wall thickness and diameter of the specimen. In this study, however, the lateral strain was determined by measuring volume changes in specimen. Specimens were prepared by the air pluviation method and gaseous carbon deozide( CO2) was used to measure precisely volumetric strain in specimen. The drained stress -strain behavior of cohesionless Boils during rotation of principal stress directions was analysed based on the results of torsion shear tests. The coupling of mal stress were applied. It was also found from the test results that the atrial strain at failure decreased with increasing value.

• Geomechanics and Engineering
• /
• v.22 no.5
• /
• pp.449-460
• /
• 2020

The double-lane arrangement model is frequently used in underground coal mines because it is beneficial to improve the mining efficiency of the working face. When the double-lane arrangement is used, the service time of the reserved roadway increases by twice, which causes several difficulties for the maintenance of the roadway. Given the severe non-uniform deformation of the reserved roadway in the Buertai Coal Mine, the stress distribution law in the mining area, the failure characteristics of roadway and the control effect of support resistance (SR) were systematically studied through on-site monitoring, FLAC 3D numerical simulation, mechanical model analysis. The research shows that the deformation and failure of the reserved roadway mainly manifested as asymmetrical roof sag and floor heave in the region behind the working face, and the roof dripping phenomenon occurred in the severe roof sag area. After the coal is mined out, the stress adjustment around goaf will happen to some extent. For example, the magnitude, direction, and confining pressure ratio of the principal stress at different positions will change. Under the influence of high-stress rotation, the plastic zone of the weak surrounding rock is expanded asymmetrically, which finally leads to the asymmetric failure of roadway. The existing roadway support has a limited effect on the control of the stress field and plastic zone, i.e., the anchor cable reinforcement cannot fully control the roadway deformation under given conditions. Based on obtained results, using roadway grouting and advanced hydraulic support during the secondary mining of the panel 22205 is proposed to ensure roadway safety. This study provides a reference for the stability control of roadway with similar geological conditions.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.9
• /
• pp.177-189
• /
• 2004

The backfilled space carl have various shapes such as vertical or lateral symmetric, unsymmetric slope depending on field conditions. Kellogg (1993) suggested the different equations for the backfill earth pressure and the lateral stress ratio considering that the stresses are different between the symmetrically sloped backfilled space and the vertical one. Kellogg (1993) assumed the stress generated on sloped wall surface as the simple internal friction angle of backfilled soil. However, Moon (1997) suggested modified Kellogg equation assuming that stress behavior in the sloped wall will be varied according to the rotation angle of principal stress and the friction of sloped wall surface. This study has compared and investigated the horizontal stresss of unsymmetrical backfilled space numerically and experimentally obtained when Kellogg lateral stress ratio is appled to and when average lateral stress ratio considering unsymmetric backfill slop of left and right are applied to the modified Kellogg equation. It is shown that the horizontal stress on the sloped wall has good match numerically and experimentally in the modified Kellogg equation when Kellogg's lateral stress ratio in symmetric condition is applied to the unsymmetric condition. But the horizontal stress on the vertical wall shows disagreement numerically and experimentally. The horizontal stress results in good agreement numerically and experimentally when the average lateral stress ratio of left and right at unsymmetric slop as applied to the modified Kellogg equation. Therefore, it is estimated that the application of the average lateral stress ratio to the left and right wall should be considered when backfilled space formed unsymmetric conditions.

• Journal of the Korean Geotechnical Society
• /
• v.15 no.6
• /
• pp.121-130
• /
• 1999

The objective of this study is to perform finite element analyses(FEA) using the anisotropic hardening constitutive model on the basis of the total stress concept. An anisotropic hardening model was then developed to solve the problem and its mathematical formulations and experimental verifications were also described. In a companion paper, the constitutive equation will be formulated for accurate and efficient solutions of FEA, and coded into a nonlinear analysis program, and finally a field problem will be analyzed. The proposed model includes the failure criterion of a von Mises type and the anisotropic hardening rule based on the generalized isotropic hardening description, which can model the nonlinearity and the anisotropy of the stress-strain relationship. As a result this study could verty the experimental results for UU triaxial tests, CU triaxial tests for overconsolidated samples, and anisotropic loading tests with the rotation of principal stress axes for $K_0$consolidated samples.

• Korean Journal of Adult Nursing
• /
• v.13 no.4
• /
• pp.560-570
• /
• 2001

Purpose: The purpose of this study is to identify factors of the causal attribution of cancer and to determine related variables. Method: Subjects were one hundred and thirty three cancer patients. The tool of the perceived causal attribution used was developed by authors and basically founded on Kim's work(1993). The SAS program was used to analyze the data along with descriptive statistics, t-test, ANOVA, Duncan's Multiple range test, and Principal component analysis and varimax rotation. Results: 1) The perceived causal attribution measurement revealed four factors; overload, destiny, stress, and constitution. The total percentage of variance explained by the four factors was 44.3%. 2) The scores of destiny on women, having religion, unemployed, lower level of education, no spouse, groups of uterine cervix and lung cancer, not receiving an operation and receiving radiation were significantly higher than those other groups. 3) The scores of stress on women, having religion, and not having a job were significantly higher than those on men, without religion, and having a job. 4) The scores of constitution on those in their forties, women, not receiving an operation and receiving radiation were significantly higher than for those in their sixties, men, receiving operation and not receiving radiation. There was no significant difference in the factor scores of overload by any variables. Conclusion: Factors of the perceived causal attribution of cancer among Korean cancer patients were overload, destiny, stress, and constitution. The scores of each factor the perceived causal attribution was significantly different by general and disease related characteristics.

• The Journal of the Petrological Society of Korea
• /
• v.8 no.3
• /
• pp.131-148
• /
• 1999

Characteristics and complex structures in the northwest Nevada, U.S.A. are de-veloped due to relative tectonic movement of major tectonostratigraphic terranes. Theresearch area is composed of autochthonous rocks of both Early Triassic Koipato Group and Middle Triassic Star Peak Group, which is located in the Humboldt Range, northwest Nevada, U.S.A. The present research is focused on deformation history, related fabric development, and state of regional paleostress during the Jurassic to Late Cretaceous. The Triassic autochthonous rocks in the Humboldt Range, Nevada, U.S.A. display polyphase deformation due to E- to ESE-directed tectonic transport of the Fencemaker allochthon over autochthonous rocks of the Humboldt Range. Structures involving the Mesozoic foreland deformation are development of intense foliation, different styles of folds, minor thrusts, transposed layering, and strong mylonitization. These tectonic structures are mostly developed along the western flank of the Humboldt Range, and are reported as the first deformation of the Mesozoic foreland in the Humboldt Range, Nevada, U.S.A. Regional principal stress(${\sigma}_1$) is interpreted to be E to ESE between the Jurassic and Early Cretaceous on the basis of orientations of strongly developed $D_1$ structures. The deformation during the Middle to Late Cretaceous, is characterized by development of consistent N- to NNE-trending metamorphic quartz veins, and shear zones parallel to pre-existing $D_1$ foliation. Orientations of metamorphic quartz veins as well as other kinematic indicators are N to NNE and are interpreted as those of regional principal stress(${\sigma}_1$) during the Late Cretaceous. The sense of shear applied in the Humbololt Range is dextral and is caused by reactivation of early-formed $D_1$ structures. These results reflect counterclockwise rotation of regional principal paleostress in the Humboldt Range from the Jurassic to Late cretaceous. Finally, development of both shear band cleavage and S/C mylonitic fabrics indicates that the shear zones in the Humboldt Range reflect involvement of enhanced non-coaxial flow during bulk shortening in mylonitic formation.

• Journal of Ocean Engineering and Technology
• /
• v.21 no.6
• /
• pp.7-15
• /
• 2007

A mechanical model was developed to predict the behavior of point-loaded RC slender beams (a/d > 2.5) without stirrups. It is commonly accepted by most researchers that a diagonal tension crack plays a predominant role in the failure mode of these beams, but the failure mechanism of these members is still debatable. In this paper, it was assumed that diagonal tension failure was triggered by the concrete cover splitting due to the dowel action at the initial location of diagonal tension cracks, which propagate from flexural cracks. When concrete cover splitting occurred, the shape of a diagonal tension crack was simultaneously developed, which can be determined from the principal tensile stress trajectory. This fictitious crack rotates onto the crack tip with load increase. During the rotation, all forces acting on the crack (i.e, dowel force of longitudinal bars, vertical component of concrete tensile force, shear force by aggregate interlock, shear force in compression zone) were calculated by considering the kinematical conditions such as crack width or sliding. These forces except for the shear force in the compression zone were uncoupled with respect to crack width and sliding by the proposed constitutive relations for friction along the crack. Uncoupling the shear forces along the crack was aimed at distinguishing each force from the total shear force and clarifying the failure mechanism of RC slender beams without stirrups. In addition, a proposed method deriving the dowel force of longitudinal bars made it possible to predict the secondary shear failure. The proposed model can be used to predict not only the entire behavior of point-loaded RC slender shear beams, but also the ultimate shear strength. The experiments used to validate the proposed model are reported in a companion paper.

• Journal of the Korea Convergence Society
• /
• v.10 no.9
• /
• pp.323-332
• /
• 2019

The purpose of this study was to examine the validity and reliability of the Revised Multidimensional Coping Scale(MCS-R) in university student who attended smoking cessation group therapy. Data were collected from 198 university students. Construct validity using exploratory factor analysis were conducted and convergent validity using Resilience scale, Patient Health Questionare-9(PHQ-9) were conducted. A Principal components analysis with varimax rotation and Kaiser normalization identified a thirteen-factor accounting for 69.7% of the variance in scores. Also, the internal consistency(0.66-0.94) and test-retest reliability was adequate(0.44-0.85) in all subscales of the MCS-R. The MCS-R has adequate psychometric characteristics so it can be used to verify.