• Steel and Composite Structures
• /
• v.35 no.6
• /
• pp.789-798
• /
• 2020

The effect of Chitosan (CS), Carbon Nanotube (CNT) and hybrid (CS-CNT) fillers on the natural frequency of drilled composite plate is investigated by experimentally in this study. The numerical validation is also made with a program based on Finite Element Method (SolidWorks). Nine types filled and one neat composite plates are used in the study. The fillers ratios are 1% CS, 2% CS, 3% CS, 0.1% CNT, 0.2% CNT, 0.3% CNT, 1% CS+0.3% CNT, 2% CS+0.3% CNT, 3% CS+0.3% CNT. The specimens cut to certain sizes by water jet from the plates 400 mm × 400 mm in dimensions. Some of them are drilled in certain dimensions with drill. The natural frequency of each specimen is measured by the vibration test set up to determine the vibration characteristic. The vibration test set up includes an accelerometer, a current source power unit, a data acquisition card and a computer. A code is written in Matlab^® program for the signal processing. The study are investigated and discussed in four main points to understand the effect of the fillers on the natural frequency of the composite plate. These are the effect of fillers contents and amounts, orientation angles of fibers, holes numbers and holes sizes. As results, the natural frequency of the plate with 1% CS and 0.1% CNT hybrid filler is lower than those of the plates with other fillers ratios for 45° orientation angle. Besides, in the composite plate with 0° orientation angle, the natural frequency increases with increasing the filler ratio. Moreover, the natural frequency increases until a certain hole number and then it decreases. Furthermore, the natural frequency is not affected until a certain hole diameter but then it decreases.

• Korean Journal of Materials Research
• /
• v.24 no.2
• /
• pp.105-110
• /
• 2014

The aim of this work was to investigate the effects of electrodeposition conditions on the microstructural characteristics of copper thin films. The microstructure of electroplated Cu films was found to be highly dependent on electrodeposition conditions such as system current and current density, as well as the bath solution itself. The current density significantly changed the preferred orientation of electroplated Cu films in a DC system, while the solution itself had very significant effects on microstructural characteristics in a pulse-reverse pulse current system. In the DC system, polarization at high current above 30 mA, changed the preferred orientation of Cu films from (220) to (111). However, Cu films showed (220) preferred orientation for all ranges of current density in the pulse-reverse pulse current system. The grain size decreased with increasing current density in the DC system while it remained relatively constant in the pulse-reverse pulse current system. The sheet resistance increased with increasing current density in the DC system due to the decreased grain size.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2002.04a
• /
• pp.284-289
• /
• 2002

In this paper, we develop a six-axes machining center tool(MCT) and CAD/CAM system based RAD Tool Program. The MCT consists of two mechanical parts, i.e., a X-Y-Z Cartesian coordinate typed MCT and a parallel-typed tilting table. Kinematics and singularity are accomplished to design the parallel-typed tilting table, and RAD Tool Program Is developed for the six-axes MCT, which requires the commands of position as well as orientation for machining of complex shape. In RAD Tool, the CAD/CAM system has a tool path generator, NC code generator and a graphic simulator. This paper designs the parallel-typed tilting table to meet the desired specification and presents the results of CAD/CAM system based RAD Tool Program.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.30 no.12 s.255
• /
• pp.1518-1525
• /
• 2006

Finite element analyses of structures made of the fiber reinforced composites require an adequate method to characterize the high anisotropic behavior induced by one or several layers of fiber cords with different spatial orientation embedded in a rubber matrix. This paper newly proposes a continuum based rebar element considering change of the orientation of the fiber during deformation of the composite. The mechanical behavior of the embedded fiber is modeled using two-node bar elements in order to consider the relative deformation and spatial orientation of the embedded fiber. For improvement of the analysis accuracy, the load-displacement curve of fiber is applied to the stiffness matrix of fiber. A finite element program is constructed based on the total Lagrangian formulation considering both geometric and material nonlinearity. Finite element analyses of the tensile test are carried out in order to evaluate the validity of the proposed method. Analysis results obtained with the proposed method provides realistic representation of the fiber reinforced rubber composite compared to results of other two models by the Halpin-Tsai equation and a rebar element in ABAQUS/Standard.

• Journal of the Korean Society of Food Culture
• /
• v.27 no.1
• /
• pp.19-29
• /
• 2012

The purpose of this study was to understand interrelationships among switching costs, customer satisfaction, and switching intent in a family restaurant. Based on a total of 427 customers obtained from empirical research, this study reviewed the reliability and fitness of the research model and verified a total of five hypotheses using the Amos program. The hypothesized relationships in the model were tested simultaneously by using a structural equation model (SEM). The proposed model provided an adequate fit to the data, ${\chi}^2$=137.881 (df=50); p< .001; CMIN/df 2.758; GFI= .947; AGFI= .919, NFI= .965; IFI= .978; TLI= .970; CFI= .978; RMR= .047; RMSEA= .064. The results showed that switching cost (${\beta}$= .123) in a family restaurant had a positive (+) influence upon customer satisfaction. Further, switching cost had a significantly negative (-) effect on switching intent (${\beta}$= -.414). In addition, there were moderating effects related to customer knowledge and variety seeking orientation in terms of the causal relationships between switching costs, customer satisfaction, and switching intent. Limitations and future research directions are also discussed.

• Child Health Nursing Research
• /
• v.26 no.4
• /
• pp.422-433
• /
• 2020

Purpose: This study describes the development of a violence prevention educational program for elementary school children using empathy (VPEP-E) that teachers can use during class. Methods: Hoffman's theory of empathy and Seels and Richey's (1994) ADDIE model were applied to develop this program. Results: The developed program consisted of eight sessions: "Orientation/definition of violence and empathy", "Types and boundaries of violence", "Look into my feelings", "Say it with a facial expression", "Preventing non-empathic violence due to social prejudice", "Preventing physical violence", "Verbal and online violence prevention: empathic conversation", and "I can do well: review of the whole curriculum". The program was evaluated by 15 elementary school teachers, who considered it to be easily accessible to elementary school students. The final VPEP-E, which will be provided in eight times for 40 minutes each for fifth-grade students, will provide a basis for preventing violence by fostering empathy. Conclusion: We expect the developed educational program to be effective in preventing violence among elementary school students. However, further research involving children from various age groups is needed.

• Child Health Nursing Research
• /
• v.27 no.3
• /
• pp.243-255
• /
• 2021

Purpose: This study aimed to develop and examine the effects of a psychosocial adaptation program for North Korean adolescent defectors. Methods: This quasi-experimental study was conducted with 28 North Korean adolescent defectors who were recruited through alternative schools. The experimental and control groups consisted of 14 participants each. A program was conducted across eight sessions, each lasting about 90-120 minutes. The data were analyzed using the x² test, t-test, paired t-test, and analysis of covariance. Results: No significant differences were observed in the score changes for psychosocial adaptation (t=0.25, p=.808), post-traumatic stress symptoms (t=0.32, p=.749), cultural adaptation stress (t=0.05, p=.957), and self-efficacy (t=0.35, p=.726) in either group before and after the intervention. No intergroup differences were observed for psychosocial adaptation (t=0.12, p=.902), post-traumatic stress symptoms (t=0.07, p=.946), cultural adaptation stress (t=0.01, p=.994), and self-efficacy (t=0.58, p=.570). Conclusion: These findings suggest that psychosocial adaptation, stress, and self-efficacy cannot be improved by a short-term intervention program alone. It was also determined that the cultural characteristics of the North Korean adolescent defectors were not sufficiently considered before implementing the program. Therefore, it is essential to provide an in-depth orientation for the participants before implementing the program.

• Journal of Korean Home Economics Education Association
• /
• v.20 no.1
• /
• pp.101-116
• /
• 2008

Most who were polled stated that they use the internet everyday. Also, it is undeniable that Internet has become one of the popular shopping markets with the spatial-convenience and time-saving it provides. With the growth of Internet and Internet shopping malls, effects on clothing purchasing of adolescents. The purpose of this study was to investigate the clothing shopping orientation and Internet clothing purchasing type of high school students. Subjects were 685(male 354, female 331) high school students located in Jeollabukdo province. In this statistical analysis, SPSS 11.5 for Windows Program. These data were analyzed by factor analysis, $x^2$ test, t-test, One-way Anova, Duncan' multiple range, Pearson's correlation coefficient. The results of this study were as follows. Six dimensions of clothing shopping orientation were derived by factor analysis: fashion hedonic shopping brand ostentation time convenience economic esthetics orientation. The clothing purchasing type in Internet had 3 factors(convenience active impulse buying economic pursuit). The groups were significantly different in regard to clothing shopping orientation, clothing purchasing type in Internet shopping mall according to demographic variables(gender, educational background of parents, a school record). Clothing shopping orientation variables had positive correlations except of hedonic shopping economic orientation with clothing purchasing type in Internet. As a conclusion, high school students' shopping orientation and purchasing type of apparel in Internet shopping mall constituted important characteristics which could affect directly Internet purchase behavior of adolescents. These results should be fundamental information for clothing and textile education in secondary school.

• Journal of Korean Academy of Fundamentals of Nursing
• /
• v.18 no.4
• /
• pp.452-462
• /
• 2011

Purpose: The purpose of this study was to examine the factors affecting body image among undergraduate students. Method: The research design for this study was a descriptive survey design using a convenience sampling. Data collection was done using self-report questionnaires with 319 undergraduate students located in 3 cities, Seoul, Gangneung and Seosan. Pearson correlation coefficients and hierarchical multiple regression with the SPSS Win 12.0 Program were used to analyze the data. Results: In the hierarchical multiple regression analysis, gender, height, weight and college major were controlled. Body surveillance and body shame significantly predicted 72.3% of appearance orientation. Sociocultural attitudes toward appearance and self-esteem significantly predicted 33.5% of appearance evaluation. Self-esteem and body surveillance significantly predicted 15.9% of health orientation. Self-esteem significantly predicted 23.3% of health evaluation. Conclusion: Findings from this study provide a comprehensive understanding of body image and related factors in undergraduate students in Korea. However, further study with a larger random sample and more a detailed research design is necessary.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.13 no.3
• /
• pp.31-43
• /
• 2011

This study investigates the differences in the purchasing behavior of infant & children's wear with the features of children and consumers. This study conducted a survey on female buyers of infant & children's wear. 558 questionnaires were analyzed by using SPSS 18.0 statistic program with factor analysis, Cronbach's ${\alpha}$, cluster analysis, ANOVA, and paired t-test. The results are as follows: 1. The buyer's value was identified with 3 factors: mental achievement value, social achievement value, and pleasure value. Three types of group by values were identified: group seeking mental social achievement, group seeking social achievement, and group seeking pleasure. 2. Fashion and conformity, pleasure pursuit, and reasonable price pursuit orientations showed significant differences among the value groups. 3. A significant difference was found in the imitation of wearing role models according to sibling relationships.