• Journal of the Korean Institute of Gas
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• v.15 no.4
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• pp.21-26
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• 2011

Type-3 cylinder liner has a limitation of machining the standard specimen for fracture toughness test because it has approximately 5 mm in thickness as well as a curvature. Hence, it needs to be employed a miniature specimen test technique to evaluate fracture toughness of the cylinder liner. In this study, small punch (SP) test method was employed to evaluate fracture toughness of the cylinder liner. Load-displacement curve result measured from the SP test showed that the liner material was failed during membrane stretching in the general SP load-displacement curve. Additionally, it was shown that liner material was isotropic although the amount of plastic deformation was different depending on the direction due to manufacturing process characteristics. Fracture toughness, $J_{Ic}$, was evaluated using the SP test data. The value of fracture toughness obtained was $13.0kJ/m^2$. This value was similar to that of the same kind of materials. Therefore, the fracture toughness evaluated using the SP test data was reasonable.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.57-62
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• 2013

A crack in a solid propellant increases the area of burning surface, which leads to excessive burning that causes motor failure. Therefore, it is necessary to evaluate fracture toughness of solid propellants. However, it is very difficult to measure fracture toughness of solid propellants because of the nonlinear mechanical behavior. In this study, evaluation of fracture toughness on a solid propellant was carried out under the assumption that the solid propellant is a linear viscoelastic material. Actual displacements from fracture toughness tests using CCT specimens were converted into pseudo-elastic displacements by using stress relaxation characteristics and fracture toughness was evaluated using ASTM E399 standard. Also, effects of test temperature and speed on the fracture toughness were considered.

• Korean Journal of Materials Research
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• v.10 no.1
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• pp.83-89
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• 2000

$Si_3N_4$ powder with 2wt% $Al_2O_3$ and 6wt% $Y_2O_3$ additives was sintered by gas pressure sintering (GPS) technique. The variations in the unlubricated wear behavior depending on sintering time were compared. Tribological properties depending on sintering time are associated with fracture toughness as well as flexural strength of materials. When increasing the sintering time, the larger elongated grains were formed as a result of exaggerated grain growth. As the fracture toughness and flexural strength decreased, the wear volume increased. On the basis of these experimental results, the unlubricated wear properties of silicon nitride were found to be governed mostly by both the fracture toughness and the flexural strength of the material.

• 레미콘
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• s.82
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• pp.15-24
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• 2005

• Magazine of the Korea Concrete Institute
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• v.8 no.6
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• pp.151-161
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• 1996

Recently, polypropylene fiber reinforced mortar and concrete as civil and architectural materials have been used in major countries in the world. Polypropylene fiber reinforced concrete has many advantages in terms of economical aspect, chemical stability and durability. It has been reported that polypropylene fiber can control restrained tensile stresses and cracks and increase toughness, resistance to impact, corrosion, fatigue and durability. The purpose of the present study is, therefore, to investigate the strength as well as many mechanical characteristics including toughness and shrinkage control properties. A specially devjsed shrinkage test has been applied to measure the crack control characteristics of polypropylene fiber reinforced concrete. The present study indicates that the polypropylene fiber reinforced concrete curbs greatly the crack occurrence due to shrinkage and enhances toughness resistance. The present study provides a firm base for the efficient use of polypropylene fiber reinforced concrete in actual construction such as pavements and slab structures.

• Korean Journal of Psychosomatic Medicine
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• v.6 no.2
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• pp.147-154
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• 1998

Objective : This study was designed to find the characteristics of MMPI that could influence the outcome of cognitive behavioral therapy(CBT) for panic disorder. Methods : 34 patients who met DSM-IV criteria for panic disorder with or without agoraphobia had completed 11 weekly sessions of cognitive behavioral therapy. All the patients were assessed with MMPI before the initiation of treatment. Five self-report measures including Beck Depression Inventory(BDI), Spielberger State-Trait Anxiety Inventory(STAI), Agoraphobic Cognition Questionnarie(ACQ), Body Sensation Questionnaire(BSQ), and Daily Anxiety Selfrating (0 - 8 scales) were also assessed as a pre- and post-treatment assessment. After the completion of treatment, patients were classified by the High End-State(HES) functioning group and the Low End-State(LES) functioning group for the data analysis. Results : 1) The LES group showed significantly higher scores in Hypochondriasis Scale(HS), Depression Scale(D), Hysterical Scale(Hy), Obsessive Scale(Pt), Schizophrenia Scale(Sc) and Validity Scale(F) of MMPI than the HES group. However, these differences gave impressions that the LES group had more severe symptoms rather than that they could be the factors influencing the outcome of CBT. 2) Though, the severity of symptoms of the LES group in the 5 measures of pre-assessment was basically higher than that of the HES group. The fact that both group showed the similar improvement between pre- and post-assessment supported the above interpretation. Conclusion : In regarding the above results, MMPI was not a proper tool that could provide the factors influencing the outcome of CBT. In the future study, the authors need to use a different tool that can find the personality characteristics more directly.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.4
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• pp.203-210
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• 2004

This study reviewed various current methods of evaluating the toughness of steel fiber reinforced concrete specimens and criticized the use of various multiples of first-crack deflection to define toughness indices. The load-CMOD curve to determine toughness, instead of load-deflection curve, was used. The notched steel fiber reinforced concrete specimens With different water/cement ratio(0 35, 0.40, 0.45, 0 50) and fiber volume content(0.0%, 0 5%, 1 0%, 1.5%) were tested under third point bending.

• Journal of Digital Convergence
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• v.17 no.8
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• pp.357-365
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• 2019

This study was conducted to identify correlations in clinical nurses' personality, resilience and happiness index to provide basic resources for nurses' happiness at work. Methods: From May 1 to 15, 2019, self-report questionnaires were distributed and collected from 307 of clinical nurses in 10 hospitals located in P-metropolitan city and K-province. Analyses included descriptive statistics, t-test, Analysis of Variance, Pearson's correlation coefficient, and multiple regression, conducted using IBM SPSS/WIN 24.0. Mean scores were nurses' personality 3.67, resilience 3.28, and happiness index 3.28. There were significant differences on the happiness index for: clinical experience, type of work, and leisure activities and a positive correlation between personality and resilience, between personality and happiness index and between happiness index and resilience. Happiness index was influenced by clinical experience 'Less than 1-5' (${\beta}=-.41$), '${\geq}10$' ${\beta}=-.39$), 'Less than 5-10' (${\beta}=-.34$), resilience (${\beta}=.35$), personality (${\beta}=.29$), type of work '3 shifts' (${\beta}=.12$), leisure activities (${\beta}=.10$). Explanatory power of these variables was 41%. Conclusion: Based on the findings of this study, so it is necessary to operated the career management, work management, personality training, support for resilience promotion program and leisure activities in order to increase the happiness index of hospital nurses.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.547-555
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• 2016

This study examined the characteristics of a character education program for university students by reviewing the Korean studies and incorporating the results. The research method was an integrated literature review, and for the study, 13 articles were selected by searching with key words, such as 'university student', 'character', and 'program' in 3 research databases, spanning between 2000 and 2015. The results showed that research on the character education program for university students is common, and have been studied for the purpose of self-knowledge and improvement of sociality. Regarding the effective variables, research on self-esteem has attracted the most attention. Based on the research result, the development of a program including various aspects of character is needed, and character education should be arranged over a long period of time with the cooperation of home, school, and whole society, not a one-time and temporary education.

• Journal of Digital Convergence
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• v.14 no.7
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• pp.37-43
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• 2016

This study is based on finding out how christian characteristics affects between christian theology major and non major students upon factors. Among various impacts, we especially have focused on personal profile and college life satisfaction, and what factors could relate to christian characteristics between personal characteristics variable (gender, age, grade, group activities, religion, communication time with parents, interpersonal relationship, ect.) and college satisfaction. Also, this study focused on what could be the differences between the christian theology major and non major students and if there are the differences, the survey will be analyzed and researched to figure out how much it differs from each other. Through this study christian theology major have presented the right christian virtue and had more effects of christian world view than non christian theology major students.