• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.05a
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• pp.171-176
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• 1999

Nondestructive inspection and accompanying life analysis based on fracture mechanics were the major conventional methods for evaluating remaining life of critical high temperature components in power plants. By using these conventional methods, it has been difficult to perform in-service inspection for life prediction. Also, quantitative damage evaluation due to unexpected abrupt changes in operating temperature was almost impossible. Thus, many efforts have been made for evaluating remaining life during operation of the plants and predicting real-time life usage values based on the shape of structures, operating history, and material properties. In this study, a core software for on-line life monitoring system which carries out real-time life evaluation of a critical component in power boiler(high temperature steam headers) is developed. The software is capable of evaluating creep and fatigue life usage from the real-time stress data calculated by using temperature/stress transfer Green functions derived for the specific headers and by counting transient cycles. The major benefits of the developed software lie in determining future operating schedule, inspection interval, and replacement plan by monitoring real-time life usage based on prior operating history.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.8
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• pp.3888-3910
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• 2018

As an increasing number of defense methods against control-data attacks are deployed in practice, control-data attacks have become challenging, and non-control-data attacks are on the rise. However, defense methods against non-control-data attacks are still deficient even though these attacks can produce damage as significant as that of control-data attacks. We present a method to defend against non-control-data attacks using influence domain monitoring (IDM). A definition of the data influence domain is first proposed to describe the characteristics of a variable during its life cycle. IDM extracts security-critical non-control data from the target program and then instruments the target for monitoring these variables' influence domains to ensure that corrupted variables will not be used as the attackers intend. Therefore, attackers may be able to modify the value of one security-critical variable by exploiting certain memory corruption vulnerabilities, but they will be prevented from using the variable for nefarious purposes. We evaluate a prototype implementation of IDM and use the experimental results to show that this method can defend against most known non-control-data attacks while imposing a moderate amount of performance overhead.

• Journal of Korean society of Dental Hygiene
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• v.17 no.1
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• pp.39-47
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• 2017

Objectives: Identifying influencing factors of stress in clinical practice of dental hygiene students through controlling the amount of stress in clinical practice. Methods: A self-reported questionnaire was filled out by 226 dental hygiene students in Daejeon, Cheongju and Jeolla province from March 2 to 30, 2016. The contents of the questionnaire included general characteristics (6 items), clinical practice characteristics (4 items), clinical practice stress (16 items), quality of life (24 items), health promotion behavior (20 items), OHIP (14 items), and critical thinking disposition (15 items). Data was analyzed using SPSS 19.0. for one way ANOVA, scheffe' posthoc test, Pearson correlation coefficients, and multiple regression analysis. Cronbach's alpha of clinical practice stress, quality of life, health promotion behavior, OHIP, and critical thinking disposition were 0.827, 0.913, 0.896, 0.921 and 0.778, respectively. Results: Clinical practice stress was 3.38 points, quality of life was 3.40 points, health promotion behavior was 3.21 points, OHIP was 4.21 points and critical thinking disposition was 3.17 points. Conclusions: Factors that had impact on clinical practice stress include sleeping state, satisfaction of clinical practice, practice number, and the quality of life, and they appeared statistically significant (p<0.05). This exercise showed the necessary manuals and system implementations in clinical practice, which can reduce the amount of stress in dental hygiene students.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.87-90
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• 2008

Levelized generation cost(LGC) has been widely used in assessing feed-in tariffs(FiT) for electricity generating from new and renewable energies. Current FiTs for renewable electricity in Korea have been fixed and applied with realistic economic data by the efforts of KERI(Korea Electrotechnology Research Institute) since October 2006. Some critical issues on the estimation of LGC are, however, found in KERI's report. Major issues are the estimation of capital cost, the consideration of corporate tax, and the application of economic life cycle in the formulae for LGC. These critical issues are examined and interpreted in a correct way in this paper.

• Journal of Korean Critical Care Nursing
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• v.6 no.1
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• pp.21-33
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• 2013

Purpose: The purpose of this study was to examine the relationship between lymphedema self-care management and quality of life in breast cancer patients with mastectomy and lymphedema. Methods: One hundred and eighty-six breast cancer patients with mastectomy and lymphedema (n=186) were recruited at a medical center located in Seoul. The levels of lymphedema self-care management and quality of life were measured by the scale for measurement of practice in lymphedema self-care management, European Organization for Research and Treatment of Cancer-Quality of Life Core 30 (EORTC QLQ-C30) and European Organization for Research and Treatment of Cancer-Quality of Life Questionnaire Breast Cancer Module (EORTC QLQ BR23), respectively. Data were analyzed with SPSS 18.0 program. Results: There were statistically significant correlations between lymphedema self-care management and general health status/quality of life in mastectomy patients with lymphedema (r=.30, p<.001). The physical function score of cancer related function scale (r=-.15, p=.033), fatigue score of cancer related symptom scale (r=.15, p=.036), systemic side effect score of breast cancer related symptom scale (r=.45, p=.034), and upset by hair loss (r=.27, p=.004) were significantly correlated with quality of life. Conclusion: The findings suggest that these significant factors should be considered when caring for lymphedema patients.

• Journal of Convergence for Information Technology
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• v.9 no.1
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• pp.61-67
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• 2019

The aim of this paper was to test the effects of simulation-based learning on knowledge, confidence, critical thinking disposition, and clinical competence to advanced cardiovascular life support of nursing student. This study used one group, pre-post test design. The participants of this research were 35 senior nursing students who underwent training in the medical-surgical nursing education. Data were collected by utilizing the questionnaire in two separate occasions: before and after the simulation-based training. As a result of this paper, the improvements of the knowledge, confidence, critical thinking disposition, and clinical competence to advanced cardiovascular life support were statistically significant. In conclusion, the simulation-based education has a positive effect on nursing students in the area of knowledge, confidence, critical thinking disposition, and clinical competence to advanced cardiovascular life support.

• Journal of Korean Critical Care Nursing
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• v.12 no.1
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• pp.22-35
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• 2019

Purpose : This study was to determine the levels of environmental stressor, posttraumatic stress disorder, and quality of life in intensive care units (ICU) survivors after intensive care, and to explore the factors affecting posttraumatic stress disorder and quality of life. Methods: With a longitudinal survey design, data were collected from 116 patients who were discharged from the ICU of a university hospital. The environmental stressor, posttraumatic stress disorder, and quality of life were measured immediately following and 1 month after the ICU discharge. Results: Of all the subjects, 16.4% experienced posttraumatic stress disorder after discharge. Multiple regression analysis revealed that ICU environmental stressors, experience of ICU readmission, using psychotropic drugs and narcotic analgesics, and ICU admission after surgery or cardiac intervention accounted for 22.2% of posttraumatic stress disorder. Posttraumatic stress disorder and sedation status when entering ICU accounted for 28.3% of the quality of life 1 month after ICU discharge. Conclusion: Nursing interventions focused on ICU environmental stressors would not only reduce environmental stress but also contribute to the reduction of posttraumatic stress disorder and later improvement of quality of life.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.560-568
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• 2016

The purpose of this study was to investigate the level of character, critical thinking disposition, professional self-concept, and adjustment to college life, as well as to identify the factors influencing the adjustment to college life in nursing students. The study was conducted on 166 nursing students in C and J Provinces, between May 25th and June 10th 2016. The data was analyzed using t-test, one-way ANOVA, Pearson's correlation, and multiple regression. The mean score of the adjustment to college life was 3.27 (${\pm}0.56$), character was 4.34 (${\pm}0.59$), critical thinking disposition was 3.48 (${\pm}0.40$), and professional self-concept was 2.76(${\pm}0.32$). There were positive correlations between adjustment to college life and character (r=.512, p<0.001), as well as between critical thinking disposition (r=.508, p<0.001) and professional self-concept (r=.614, p<0.001). The significant factors influencing the adjustment to college life were character, critical thinking disposition, and professional self-concept, which explained 43% of the variance in the adjustment to college life. Based on these findings, programs that develop character, critical thinking disposition, and professional self-concept are necessary for college nursing students in order to promote college adjustment.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.149-155
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• 2005

The rotating components such as turbine rotors in service are generally subjected to multiaxial cyclic loading conditions. The prediction of fatigue lift for turbine rotor components under complex multiaxial loading conditions is very important to prevent the fatigue failures in service. In this paper, axial and torsional low cycle fatigue tests were preformed for 3.5NiCrMo steels serviced low pressure turbine rotor of nuclear power plant. Several methods to predict biaxial fatigue life such as Tresca, von Mises and Brown & Miller's critical plane approach were evaluated to correlate the experimental results for serviced NiCrMoV steel. The fracture mode and fatigue characteristics of NiCrMoV steel were discussed based on the results of fatigue tests performed under the axial and torsional test conditions. In particular, the Brown and Miller's critical plane approach was found to best correlate the experimental data with predictions being within a factor of 2.

• Journal of Ocean Engineering and Technology
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• v.25 no.5
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• pp.47-51
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• 2011

This paper analyzes the fatigue-life of welded joints using the notch stress approach. In the notch stress approach, the notch effects are usually approximated by introducing weld-bead parameters for the local detailed weld joints. The actual bead shape is complex and 3-dimensional. It may also greatly influence the fatigue strength. In this study, the welded shape was modeled using a 3D-scanner. The critical distance method was adopted in the evaluation of the fatigue effective notch stress for the weldments. Fatigue life tests were performed to verify the present method of fatigue life estimation for two types of welded plates with longitudinal attachments. The estimated results of the present methods were applied to the results of the experiment. The results of the analysis showed that the scatter of fatigue-life for the experimental data expressed in the nominal stress was significantly reduced by applying the effective fatigue stress of the present study.