• Korean Journal of Occupational Health Nursing
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• v.22 no.1
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• pp.1-12
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• 2013

Purpose: This study aims to test the validity and criteria-related reliability of the Korean version of the Copenhagen Psyco-social Questionnaire version II (COPSOQ-K) assessing the psychosocial working environment. Methods: The COPSOQ-K was developed through forward-backward translation techniques, and revision based on feedback from focus groups. Survey data were collected from 311 office workers who worked in one workplace. An internal consistency reliability was estimated by Cronbach's ${\alpha}$. The impacts of the COPSOQ-K scales on job satisfaction, self-rated health, stress, sleeping troubles, burnout, and sickness absence were analyzed with multiple regression model or multiple logistic regression model, adjusted age and gender using SAS version 9.3. The Pearson correlation coefficients between the COPSOQ-K scales and Korean job stress and its subdomain were identified. Results: Cronbach's ${\alpha}$ of COPSOQ-K scales was adequate or good (0.66~0.87). The major COPSOQ-K scales predict job satisfaction, self-rated health, stress, sleeping troubles burnout, and sickness absence. The major COPSOQ-K scales were correlated with Korean job stress and its subdomain. Conclusion: The COPSOQ-K scales have satisfactory reliability and criteria-related validity. The COPSOQ-K scales will be useful for the future studies and practices associated with psychosocial working environment.

• Nuclear Engineering and Technology
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• v.36 no.6
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• pp.512-527
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• 2004

This paper describes the finite element (FE) analysis results of a 1/4 scale model of a prestressed concrete containment vessel (PCCV) by considering the tension stiffening effect, which is a result of the bond effect between the concrete and the steel. The tension stiffening model is assumed to be an exponential form based on the relationship between the average stress and the average strain of the concrete. The objective of the present FE analysis is to evaluate the ultimate internal pressure capacity of the PCCV, as well as its failure mechanism, when the PCCV model is subjected to a monotonous internal pressure beyond is design pressure capacity. With the commercial code ABAQUS, the FE analysis used two concrete failure criteria: a 2-dimensional axi-symmetric model with modified Drucker-Prager failure criteria and a 3-dimensional model with a damaged plasticity mod디. The results of our FE analysis on the ultimate pressure capacity and failure modes of PCCV have a good agreement with the experimental data.

• Journal of computational fluids engineering
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• v.16 no.4
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• pp.1-6
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• 2011

Aerodynamic characteristics depending on the shape of an internal motor in a small-size sirocco fan for residential ventilation have been investigated. For the aerodynamic analyses of the sirocco fan, three-dimensional Reynolds-averaged Navier-Stokes equations are solved with the shear stress transport model for turbulence closure. The flow analyses are performed on hexahedral grids using a finite-volume solver. The validation of the numerical results at steady-state is performed by comparing with experimental data for the pressure and efficiency. In order to investigate the aerodynamic characteristics depending on shape of an internal motor in a sirocco fan, the reference shape is analyzed compared to the case without internal motor. Additionally, two shape parameters, height and width of the internal motor in a sirocco fan, are tested to investigate their effects on the aerodynamic characteristics. The results show that the shape of the internal motor in a sirocco fan is an important factor to improve the aerodynamic performances.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.321-326
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• 2011

Aerodynamic characteristics depending on the shape of an internal motor in a small-size sirocco fan for residential ventilation have been investigated For the aerodynamic analyses of the sirocco fan, three-dimensional Reynolds-averaged Navier-Stokes equations are solved with the shear stress transport model for turbulence closure. The flaw analyses are performed on hexahedral grids using a finite-volume solver. The validation of the numerical results at steady-state is performed by comparing with experimental data for the pressure and efficiency. In order to investigate the aerodynamic characteristics depending on shape of an internal motor in a sirocco fan, the reference shape is analyzed compared to the case without internal motor. Additionally, two shape parameters, height and width of the internal motor in a sirocco fan, are tested to investigate their effects on the aerodynamic characteristics. The results show that the shape of the internal motor in a sirocco fan is an important factor to improve the aerodynamic performances.

• Korean Journal of Childcare and Education
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• v.16 no.6
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• pp.89-104
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• 2020

Objective: The purpose of this study was to examine the effects of maternal parenting stress and mother's ego-resilience on mother-child attachment. More specially, mother-child attachment for higher grade elementary school children was examined according to the internal working model. Methods: Participants were 190 mothers of fourth and fifth grade elementary school children. The Maternal Parenting Stress Scale(Shin, 1997), the Scales of Ego-resilience(Yoo & Shim, 2002), and Inventory of Parent Attachment(Yang, 2006) were used to measure variables. Collected data were analyzed by descriptive statistics, t-test, correlation analysis and multiple regression analysis. Results: The major findings were summarized as follows: First, there were no differences between mother-child attachment according to children's gender. Second, mother-child attachment was negatively correlated with maternal parenting stress and positively correlated with ego-resilience. Next, maternal parenting stress_interaction and ego-resilience explained mother-child attachment_trust. Last, maternal stress_interaction explained mother-child attachment_isolation. Conclusion/Implications: In conclusion, the study results showed that maternal parenting stress and ego-resilience influenced mother-child attachment. based on the results, the implications of this study were discussed.

• Journal of Oriental Neuropsychiatry
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• v.28 no.3
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• pp.231-248
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• 2017

Objectives: This study evaluates anti-stress and sleep-inductive effects of Dongshingihyeolyangsubang (DSGYSB) on rats induced by chronic mild stress (CMS). Methods: Twenty-five healthy rats were randomly divided into five groups: normal, CMS (Control), DSGYSB50, DSGYSB100, and DSGYSBS200. All rats except the normal group were exposed to unpredictable stress conditions such as water deprivation, empty bottles, and forced treadmill. A week after starting the experiment, rats in DSGYSB50, DSGYSB100, and DSGYSB200 groups were fed orally with water once a day for two weeks. Then blood samples were taken from the rats for analysis of complete blood count, AST, ALT, and glucose. Noradrenaline, corticosterone, serotonin, GABA and melatonin were measured by ELISA kit. BDNF, CREB, TrkB and $TNF-{\alpha}$ were measured by RT-PCT. Results: In Noradrenaline contents, the DSGYSB200 group revealed significant decrease compared to the control group. In corticosterone contents, the DSGYSB200 group revealed significant decrease compared to the control group. In serotonin contents, the DSGYSB200 group revealed significant increase compared to the control group. In GABA contents, the DSGYSB50, DSGYSB100, and DSGYSB200 groups revealed significant increase compared to the control group. In the activity of BDNF, the DSGYSB50, DSGYSB100 and DSGYSB200 groups revealed significant increase compared to the control group. In the activity of CREB, the DSGYSB100 and DSGYSB200 groups revealed a significant decrease compared to the control group. In the activity of TrkB, the DSGYSB100 and DSGYSB200 groups revealed significant decrease compared to the control group. In the activity of $TNF-{\alpha}$, DSGYSB100 and DSGYSB200 groups revealed significant decrease compared to the control group. In glucose contents, the DSGYSB100 and DSGYSB200 groups revealed significant decrease compared to the control group. In the leukocyte changes, white blood cells, neutrophil, lymphocytes, and monocyte significantly increased in the DSGYSB100 and DSGYSB200 groups than the control group. In the erythrocyte changes, hemoglobin significantly increased in the DSGYSB200 group than the control group. Conclusions: Results suggest that Dongshingihyeolyangsubang has anti-stress and sleep-inductive effects on rats induced by CMS.

• Geomechanics and Engineering
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• v.28 no.5
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• pp.505-520
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• 2022

In recent years, geotextile-encased gravel columns (usually called stone columns) have become a popular method to increasing soil shear strength, decreasing the settlement, acceleration of the rate of consolidation, reducing the liquefaction potential and increasing the bearing capacity of foundations. The behavior of improved loose base-soil with gravel columns under shear loading and the shear stress-horizontal displacement curves got from large scale direct shear test are of great importance in understanding the performance of this method. In the present study, by performing 36 large-scale direct shear tests on sandy base-soil with different fine-content of zero to 30% in both not improved and improved with gravel columns, the effect of the presence of gravel columns in the loose soils were investigated. The results were used to predict the shear stress-horizontal displacement curve of these samples using support vector machines (SVM). Variables such as the non-plastic fine content of base-soil (FC), the area replacement ratio of the gravel column (Arr), the geotextile encasement and the normal stress on the sample were effective factors in the shear stress-horizontal displacement curve of the samples. The training and testing data of the model showed higher power of SVM compared to multilayer perceptron (MLP) neural network in predicting shear stress-horizontal displacement curve. After ensuring the accuracy of the model evaluation, by introducing different samples to the model, the effect of different variables on the maximum shear stress of the samples was investigated. The results showed that by adding a gravel column and increasing the Arr, the friction angle (ϕ) and cohesion (c) of the samples increase. This increase is less in base-soil with more FC, and in a proportion of the same Arr, with increasing FC, internal friction angle and cohesion decreases.

• Smart Media Journal
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• v.12 no.11
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• pp.1-9
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• 2023

Stress is a significant issue in modern society, often triggered by external or internal factors that are difficult to manage. When high stress persists over a long term, it can develop into a chronic condition, negatively impacting health and overall well-being. However, it is challenging for individuals experiencing chronic stress to recognize their condition, making early detection and management crucial. Using biosignals measured from wearable devices to detect stress could lead to more effective management. However, there are two main problems with using biosignals: first, manually extracting features from these signals can introduce bias, and second, the performance of classification models can vary greatly depending on the subject of the experiment. This paper proposes a model that reduces bias using convo utional autoencoders, which can represent the key features of data, and enhances generalizability by employing soft voting, a method of ensemble learning, to minimize performance variability. To verify the generalization performance of the model, we evaluate it using LOSO cross-validation method. The model proposed in this paper has demonstrated superior accuracy compared to previous studies using the WESAD dataset.

• Journal of Dental Rehabilitation and Applied Science
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• v.21 no.1
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• pp.1-14
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• 2005

The purpose of this study was to assess the loading distributing characteristics of implant prosthesis of internal connection system(ITI system) according to position and direction of load, under vertical and inclined loading using finite element analysis (FEA). The finite element model of a synOcta implant and a solid abutment with $8^{\circ}$ internal conical joint used by the ITI implant was constructed. The gold crown for mandibular first molar was made on solid abutment. Each three-dimensional finite element model was created with the physical properties of the implant and surrounding bone. This study simulated loads of 200N at the central fossa in a vertical direction (loading condition A), 200N at the outside point of the central fossa with resin filling into screw hole in a vertical direction (loading condition B), 200N at the centric cusp in a $15^{\circ}$ inward oblique direction (loading condition C), 200N at the in a $30^{\circ}$ inward oblique direction (loading condition D) or 200N at the centric cusp in a $30^{\circ}$ outward oblique direction (loading condition E) individually. Von Mises stresses were recorded and compared in the supporting bone, fixture, and abutment. The following results have been made based on this study: 1. Stresses were concentrated mainly at the ridge crest around implant under both vertical and oblique loading but stresses in the cancellous bone were low under both vertical and oblique loading. 2. Bending moments resulting from non-axial loading of dental implants caused stress concentrations on cortical bone. The magnitude of the stress was greater with the oblique loading than with the vertical loading. 3. An offset of the vertical occlusal force in the buccolingual direction relative to the implant axis gave rise to increased bending of the implant. So, the relative positions of the resultant line of force from occlusal contact and the center of rotation seems to be more important. 4. In this internal conical joint, vertical and oblique loads were resisted mainly by the implant-abutment joint at the screw level and by the implant collar. Conclusively, It seems to be more important that how long the distance is from center of rotation of the implant itself to the resultant line of force from occlusal contact (leverage). In a morse taper implant, vertical and oblique loads are resisted mainly by the implant-abutment joint at the screw level and by the implant collar. This type of implant-abutment connection can also distribute forces deeper within the implant and shield the retention screw from excessive loading. Lateral forces are transmitted directly to the walls of the implant and the implant abutment mating bevels, providing greater resistance to interface opening.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.173-180
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• 2004

This paper presents the effect of varying boundary conditions such as ground subsidence, internal pressure and temperature variation for buried pipelines on failure prediction by using a failure probability model. The first order Taylor series expansion of the limit state function incorporating with von-Mises failure criteria is used in order to estimate the probability of failure mainly associated with three cases of ground subsidence. Using stresses on the buried pipelines, we estimate the probability of pipelines with von-Mises failure criterion. The effects of varying random variables such as pipe diameter, internal pressure, temperature, settlement width, load for unit length of pipelines, material yield stress and pipe thickness on the failure probability of the buried pipelines are systematically studied by using a failure probability model for the pipeline crossing ground subsidence regions which have different soil properties.