• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2475-2482
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• 2002

The measurement of residual stresses by the hole-drilling method has been commonly used to evaluate residual stresses in structural members. In this method, eccentricity can usually occur between the hole center and rosette gage center. In this study, the error due to the hole eccentricity is compensated using the neural network. The neural network has trained training examples of normalized eccentricity, eccentric direction and direction of maximum stress at eccentric case using backpropagation learning process. The trained neural network could compensated the error of measured residual stress in experiments with hole eccentricity. The proposed neural network is very useful for compensation of the error due to hole eccentricity in hole-drilling method.

• Science of Emotion and Sensibility
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• v.15 no.4
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• pp.527-540
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• 2012

We examined the effect of delayed and immediate rewards on short- and long-term memory performance depending on the level of stress. It has been demonstrated that delaying feedback during memory tasks could lead to better retention than presenting it immediately (a.k.a., feedback delay benefit or delay-retention effect). In this study, we manipulated stress level(high-stress or low-stress), reward-timing(delayed or immediate reward), reward-existence(500 or 0 won) and retrieval-timing(delayed or immediate memory test). On the high-stress learning condition, one week later, the number of correct answers with delayed-rewards were significantly more than that of delayed-no-rewards but there was not any difference between immediate-rewards and immediate-no-rewards. On the other hand, in the high-stressful immediate memory test, immediate-rewards only had a positive effect on memory performance. The results indicated that delayed rewards improved long-term memory performance by promoting memory consolidation and the sensitivity to rewards was higher under the high-stress condition.

• Nutrition Research and Practice
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• v.6 no.2
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• pp.146-154
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• 2012

The purposes of this study are to estimate the stress level of university students, and to verify the relationships between stress level and drinking behavior. A questionnaire survey was administered to 430 university students in the Gangwon area in Korea from November 5 to November 28, 2008, and data from 391 students were used for the final statistical analysis. The most stressful factor was "Worry about academic achievements" (2.86 by Likert-type 4 point scale). The subjects were divided into two groups, a low stress group (${\leq}65.0$) and a high stress group (${\geq}66.0$), by the mean value (65.1) and median value (66.0) of the stress levels. The drinking frequency was not different between the two stress groups, but the amount of alcohol consumption was significantly different ($P$ < 0.05). The portion of students reporting drinking "7 glasses or over" was higher in the lower stress group than in the higher stress group. In addition, factor 6, "Lack of learning ability", was negatively correlated with drinking frequency and the amount of alcohol consumption ($P$ < 0.05), and factor 3, "Worry about academic achievements", was negatively correlated with the amount of drinking ($P$ < 0.05). The major motive for drinking was "When overjoyed or there is something to celebrate" (2.62), and the main expected effect of drinking was "Drinking enables me to get together with people and shape my sociability" (2.73). The higher stress group showed significantly higher scores on several items in the categories of motives ($P$ < 0.01), negative experience ($P$ < 0.05), and expected effects ($P$ < 0.05) of drinking than the lower stress group. Our results imply that university students at the lower stress level may drink more from social motives in positive drinking environments, while those at the higher stress level may have more problematic-drinking despite their smaller amount of alcohol consumption.

• Geomechanics and Engineering
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• v.37 no.1
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• pp.49-64
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• 2024

Rocks undergoing repeated loading and unloading over an extended period, such as due to earthquakes, human excavation, and blasting, may result in the gradual accumulation of stress and deformation within the rock mass, eventually reaching an unstable state. In this study, a CNN-CCM is proposed to address the mechanical behavior. The structure and hyperparameters of CNN-CCM include Conv2D layers × 5; Max pooling2D layers × 4; Dense layers × 4; learning rate=0.001; Epoch=50; Batch size=64; Dropout=0.5. Training and validation data for deep learning include 71 rock samples and 122,152 data points. The AI Rock Constitutive Model learned by CNN-CCM can predict strain values(ε₁) using Mass (M), Axial stress (σ₁), Density (ρ), Cyclic number (N), Confining pressure (σ₃), and Young's modulus (E). Five evaluation indicators R², MAPE, RMSE, MSE, and MAE yield respective values of 0.929, 16.44%, 0.954, 0.913, and 0.542, illustrating good predictive performance and generalization ability of model. Finally, interpreting the AI Rock Constitutive Model using the SHAP explaining method reveals that feature importance follows the order N > M > σ₁ > E > ρ > σ₃.Positive SHAP values indicate positive effects on predicting strain ε₁ for N, M, σ₁, and σ₃, while negative SHAP values have negative effects. For E, a positive value has a negative effect on predicting strain ε₁, consistent with the influence patterns of conventional physical rock constitutive equations. The present study offers a novel approach to the investigation of the mechanical constitutive model of rocks under cyclic loading and unloading conditions.

• Journal of The Korean Society of Integrative Medicine
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• v.12 no.3
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• pp.11-24
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• 2024

Purpose : This study aims to identify the factors influencing health-related quality of life through machine learning of the general characteristics of patients with hypertension and to provide a basis for related research on patients, such as intervention strategies and management guidelines in the field of physical therapy for health promotion. Methods : Annual data from the second Korean Health Panel (Version 2.0) from 2019 to 2020, conducted jointly by the Korea Health and Social Research Institute and the National Health Insurance Service, were analyzed (Korea Health Panel, 2024). The data used in this study was collected from January to July 2020, and the data was collected using computer-assisted face-to-face interviews. Of the 13,530 household members surveyed, 1,368 were selected as the final study participants after removing missing values from 3,448 individuals diagnosed with hypertension by a doctor. Results : The results showed that walking (P2) was the most significant factor affecting health-related quality of life in random forest, followed by perceived stress (HS1), body mass index (BMIc), total household income (TOTc), subjective health status (SRHc), marital status (Marr), and education level (Edu). Conclusion :To prevent and manage chronic diseases such as hypertension, as well as to provide customized interventions for patients in advanced stages of the disease, research should be conducted in the field of physical therapy to identify influencing factors using machine learning. Based on the findings of this study, we believe that there is a need for additional content that can be utilized in the field of physical therapy to improve the health-related quality of life of patients with hypertension, such as diagnostic assessment and intervention management guidelines for hypertension, and education on perceived stress and subjective health status.

• The Journal of the Korea Contents Association
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• v.18 no.10
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• pp.453-463
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• 2018

An analysis including ASE model accessing based on the intention of behavior performance of online university students is a new approach to improve academic persistence considering the characteristics of students with extensive personal variables, a uniqueness of learning environment. This study aimed to identify the relationship between ASE model including academic stress and academic persistence, and the effect of these factors on academic persistence of online university students. Data were collected from 181 sophomores in K open university from March to June, 2018. Frequency analysis, ${\chi}^2-test$, t-test, F-test, Pearson's correlation analysis, and multiple regression analysis used for data analysis. For factors affecting academic persistence, academic stress (${\beta}=-.16$, p=.016), online learning attitude (${\beta}=.44$, p<.001), and social support among social influential factors (${\beta}=.16$, p=.045) were statistically significant and the prediction model of academic persistence showed 29% explanation power (F=15.76, p<.001). To enhance academic persistence of online university students, it is needed to develop programs to reduce academic stress, improve attitude toward online learning, and improve social support.

• Journal of Technologic Dentistry
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• v.41 no.3
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• pp.233-244
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• 2019

Purpose: The purpose of the study is to learn the importance of self-directed learning about career-preparation behavior of department of dental technology students. Methods: Using the questionnaire, the department of dental technology in Gyeongnam Province conducted a survey of students of department of dental technology at A and B college for one month from May 15, 2019 through June 15, 2019, and finally 204 students were surveyed for Self-esteem, Self-determination, Self-efficacy, Internal control, College life adaptation, Self-directed learning, and Career-preparation behavior. Results: Self-esteem among students has been shown to improve self-directed learning by increasing the stress of college life, and self-efficacy has only a direct effect on self-directed learning. In addition, self-determination and internal control of department of dental technology students were found to be variables that have a common positive effect on college life adaptation and self-directed learning. In addition, college life adaptation gives direct positive effect to self-directed learning, but indirect effect through self-directed learning was found to be stronger than direct effect on career-preparation behavior, and the career-preparation behavior of students was further strengthened through self-directed learning. Conclusion: The changes in college restructuring and various policies also suggest that students should actively seek ways to instill certainty about their major's vision and career path within the college rather than deciding their future through extreme measures such as academic secession at a time when anxiety and uncertainty about their career is strong.

• The Journal of Korean Academic Society of Nursing Education
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• v.22 no.1
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• pp.14-24
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• 2016

Purpose: The purpose of this study was to identify the impact of academic stress on depression suffered by college nursing students and the moderating effects of academic resilience. Methods: For this survey, 257 students (1st and 2nd year) participated, and it was performed over two weeks in September 2014. In this study, statistical analysis was conducted using SPSS 18.0 for Windows and as a t-test, ANOVA, Pearson correlation, and multiple regression analysis. Results: The students' academic stress had a significant impact on their depression (${\beta}=.279$). The moderating effects of academic resilience did not have a significant impact, which is presumably as a result of there being more complex, nonlinear effects, rather than a simple, linear relationship between academic stress and resilience. Conclusion: It may be incorrect to assume that academic resilience is a moderating variable that lessens academic stress. It is implied that academic resilience can have a significant impact when internal and external support conditions are met, and that the effects can be reinforced when family support, a learning environment, and improved adaptability to life at school are also provided.

• The Korean Journal of Community Living Science
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• v.17 no.3
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• pp.29-41
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• 2006

The purpose of this research is to study the causal model among mother related variables, child abuse, and children's emotional maladjustment behaviors. The sample subjects were 542 pairs of fifth and sixth grade elementary school students and first as well as eighth grade middle school students, and their mothers. The major findings of the research are as follows: First, the result of multiple regression analysis on the effects of the maternal parenting stress and marital satisfaction to the children's abuse indicates that stress related to learning expectation and stress related to relationship with child are the significant contributing factor to physical abuse and verbal abuse. Second, the result of multiple regression analysis on the effects of the maternal parenting stress and child abuse to the children's emotional maladjustment behaviors indicate that verbal abuse is the significant contributing factor. Third, looking at causal relations of the maternal variables (maternal parenting stress, marital satisfaction) and child abuse (physical abuse, verbal abuse, neglect) to the children's emotional maladjustment behaviors, maternal variables impact indirectly through the child abuse factor.

• Journal of Korean Academy of Nursing
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• v.38 no.1
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• pp.152-160
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• 2008

Purpose: It has been attempted to support mother of premature infants by providing information of premature infant care using e-Learning because premature infants need continuous care from birth to after discharge. Method: The e-Learning Program for mother of premature was developed with Xpert, Namo web editor, Adobe Photoshop, and PowerPoint and applied for 4 weeks from 4 to 30 September 2006. Result: 1) We found that the contents of information which premature infants' need when being in the hospital and after discharge were the definition of a premature infant, orientation of NICU, care of premature infants, care of premature infants' common diseases, the connection of healthcare resources, exchange of information, and the management of rearing stress. 2) The program content consisted of cause of premature birth, comparison to full-term baby, physiology character, orientation of NICU, common health problems, follow up care, infection control, feeding, normal development physically and mentally, weaning method, and vaccination. Conclusion: Considering the results, this program for mother of premature is a useful means to provide premature-care information to mothers. This information can be readily accessible and can be varied and complex enough to be able to help mothers to the information and assistance they require.