• Smart Structures and Systems
• /
• v.3 no.2
• /
• pp.189-200
• /
• 2007

As a functional material, shape memory alloy (SMA) has attracted much attention and research effort to explore its unique properties and its applications in the past few decades. Some of its properties, in particular the electrical resistance (ER) based self-sensing property of SMA, have not been fully studied. Electrical resistance of an SMA wire varies during its phase transformation. This variation is an inherent property of the SMA wire, although it is highly nonlinear with hysteresis. The relationship between the displacement and the electrical resistance of an SMA wire is deterministic and repeatable to some degree, therefore enabling the self-sensing ability of the SMA. The potential of this self-sensing ability has not received sufficient exploration so far, and even the previous studies in literature lack generality. This paper concerns the utilization of the self-sensing property of a spring-biased Nickel-Titanium (Nitinol) SMA actuator for two applications: ER feedback position control of an SMA actuator without a position sensor, and estimation of the opening of a SMA actuated valve. The use of the self-sensing property eliminates the need for a position sensor, therefore reducing the cost and size of an SMA actuator assembly. Two experimental apparatuses are fabricated to facilitate the two proposed applications, respectively. Based on open-loop testing results, the curve fitting technique is used to represent the nonlinear relationships between the displacement and the electrical resistance of the two SMA wire actuators. Using the mathematical models of the two SMA actuators, respectively, a proportional plus derivative controller is designed for control of the SMA wire actuator using only electrical resistance feedback. Consequently, the opening of the SMA actuated valve can be estimated without using an extra sensor.

• Child Health Nursing Research
• /
• v.22 no.1
• /
• pp.1-10
• /
• 2016

Purpose: Purpose of this study was to investigate factors influencing wellness, and provide basic data for development of intervention programs to improve wellness in mothers of children with disabilities. Methods: Participants were 147 mothers of children with disabilities from an elementary school and kindergarten for children with disabilities located in J and C cities in G province. Data were collected from February 24 to April 24, 2015 using questionnaires. Results: Mean scores were $3.24{\pm}0.38$ of 5 for wellness, $2.40{\pm}0.41$ of 4 for self-esteem, and $2.87{\pm}0.36$ of 4 for family function. There were significant differences in wellness according to religion, education, and type of education program for the children. There were positive correlations between self-esteem, family function, social support, and wellness. Factors influencing wellness were selfesteem (${\beta}$ =.450), family function (${\beta}$ =.313), type of education program for the children (${\beta}$ =.140), and religion (${\beta}$ =.127). These factors explained 42.7% of the variance in wellness. Conclusion: Findings show that levels of wellness in these mothers are not sufficient to allow them to care for their children and to maintain their own overall health. Therefore to increase wellness of mothers of children with disabilities, intervention strategies that focus on improving self-esteem and family functioning need to be developed.

• Smart Structures and Systems
• /
• v.29 no.6
• /
• pp.757-766
• /
• 2022

To train deep learning algorithms, a sufficient number of data are required. However, in most engineering systems, the acquisition of fault data is difficult or sometimes not feasible, while normal data are secured. The dearth of data is one of the major challenges to developing deep learning models, and fault diagnosis in particular cannot be made in the absence of fault data. With this context, this paper proposes an anomaly detection methodology for rotating machines using only normal data with self-labeling. Since only normal data are used for anomaly detection, a self-labeling method is used to generate a new labeled dataset. The overall procedure includes the following three steps: (1) transformation of normal data to self-labeled data based on a pretext task, (2) training the convolutional neural networks (CNN), and (3) anomaly detection using defined anomaly score based on the softmax output of the trained CNN. The softmax value of the abnormal sample shows different behavior from the normal softmax values. To verify the proposed method, four case studies were conducted, on the Case Western Reserve University (CWRU) bearing dataset, IEEE PHM 2012 data challenge dataset, PHMAP 2021 data challenge dataset, and laboratory bearing testbed; and the results were compared to those of existing machine learning and deep learning methods. The results showed that the proposed algorithm could detect faults in the bearing testbed and compressor with over 99.7% accuracy. In particular, it was possible to detect not only bearing faults but also structural faults such as unbalance and belt looseness with very high accuracy. Compared with the existing GAN, the autoencoder-based anomaly detection algorithm, the proposed method showed high anomaly detection performance.

• Knowledge Management Research
• /
• v.24 no.3
• /
• pp.127-148
• /
• 2023

Traditional Business Intelligence environment is limited to support the rapidly changing businesses and the exponential growth of data in both volume and complexity of data. Companies should shift their business intelligence environment into Self-Service Business Intelligence (SSBI) environment in order to make smarter and faster decisions. However, firms seem to face various challenges in implementing and leveraging the effective business intelligence system, and academics do not provide sufficient studies related including the success factors of SSBI. This study analyzes the three cases of Korean companies in depth, their development process and the assessment of business intelligence, based on the theoretical model on the key success factors of business intelligence systems. The comparative analysis of the three cases including project managers' interviews and performance evaluations provide rich implications for the successful adoption and the use of business intelligence systems of firms. The study is expected to provide useful references for firms to fully leverage the effects of business intelligence systems and upgrade towards self-service business intelligence systems.

• Journal of Science Education
• /
• v.41 no.3
• /
• pp.351-364
• /
• 2017

This study investigated science self-efficacy, sources of science self-efficacy, and creative personality by grade and gender. For this study, 495 $3^{rd}-6^{th}$ elementary students were participated. The findings showed that there was no significant difference by grade and gender in science self-efficacy. In sources of science self-efficacy, there was significant differences by gender, but not by grade. $3^{rd}$ and $4^{th}$ graders' scores about 'vicarious experiences' and 'physiological and affective states' were higher than the those of $5^{th}$ and $6^{th}$ graders. Among creative personality, $3^{rd}$ and $4^{th}$ graders' scores about 'motivation' and 'challenge' were higher than those of $5^{th}$ and $6^{th}$ graders. Comparing the scores among sources of science self-efficacy, the mean scores of 'social persuasion' were relatively low than other sources. This showed that praises and encouragement of teacher, parents and friends had not been sufficient. In terms of variables' influences on science self-efficacy, multiple regression results showed that 'mastery experiences' in sources of science self-efficacy had the most explanatory power and 'social persuasion' had the second explanatory power. 'Patience' in creative personality showed the third explanatory power. The variables' influences on science self-efficacy showed differences by grade and gender.

• Korean Journal of Social Welfare
• /
• v.67 no.4
• /
• pp.251-277
• /
• 2015

This qualitative study is designed for the reconstruction of the experience of single mothers in poverty based on the bottom-up approach. Welfare dependency is identified as vital help to protect their own and children's lives, through their stories telling that welfare services provided by government and community take care of them "in place of their husbands", and "raise them up by hand." What is self-sufficiency to them is more of a process-orientation through welfare dependency than a state out of it, and a way to look through building their self-esteem and working to discover their self-worth except their economic power. Restoring their potential to self-sufficiency through dealing with their psycho-social stresses and expanding services for them related to child-care(education) and occupation ability development for long-term self-sufficiency, rather than hasty focusing on welfare exit, should be built on the foundation of helping them self-sufficient. In order for the self-sufficiency program to overcome the participant's images of "subordination and stigma" and to convey the original meaning of "welfare to work", the performance and evaluation system of self-sufficiency programs that reflects the insider's perspectives on their participation motive and process, and the self-sufficiency program customized for their needs and interests should be encouraged to develop.

• Rapid Communication in Photoscience
• /
• v.3 no.4
• /
• pp.81-84
• /
• 2014

To examine the microenvironmental effect of DNA on the photosensitized reaction, the electron-donor-connecting porphyrin, meso-(9-phenanthryl)-tris(N-methyl-p-pyridinio) porphyrin (Phen-TMPyP), was synthesized. Phen-TMPyP can bind to oligonucleotides with two binding modes, depending on the DNA concentration. The fluorescence lifetime measurement of Phen-TMPyP shows a shorter component than that of the reference porphyrin without the phenanthryl moiety. However, the observed value is much longer than those of previously reported similar types of electron-donor-connecting porphyrins, suggesting that electron-transfer quenching by the phenanthryl moiety is not sufficient. The fluorescence quantum yield of Phen-TMPyP ($5{\mu}M$) decreased with an increase in DNA concentration of up to $5{\mu}M$ base pair (bp), possibly due to self-quenching through an aggregation along the DNA strand, increased with an increase in DNA concentration of more than $5{\mu}M$ bp and reached a plateau. The fluorescence quantum yield of Phen-TMPyP with a sufficient concentration of DNA was larger than that of the reference porphyrin. The singlet oxygen ($^1O_2$) generating activity of Phen-TMPyP was confirmed by the near-infrared emission spectrum measurement. The quantum yield of $^1O_2$ generation was decreased by a relatively small concentration of DNA, possibly due to the aggregation of Phen-TMPyP, and recovered with a sufficient concentration of DNA. The recovered quantum yield was rather smaller than that without DNA, indicating the quenching of $^1O_2$ by DNA. These results show that a DNA strand can stabilize the photoexcited state of a photosensitizer and, in a certain case, suppresses the $^1O_2$ generation.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.15 no.1
• /
• pp.247-257
• /
• 2020

In recent years, the proportion of youth's self-employed is steadily increasing, and government policy also actively encourages youth to become an entrepreneur. However, most of the domestic precedent studies on the self-employed labor market focus on the middle-aged and the elderly, and previous studies on the self-employed labor market of young people are hardly ever studied. Above all, the study that examines the factors of entry into self-employment of young people is not sufficient and researchers usually utilize the study about for all ages to explain the self-employment market of young people. However, because the young and middle-aged people differ in labor market conditions, family backgrounds, and the level of accumulation of human capital, separate explanations and theories are needed. Therefore, this study explored the factors of entry into self-employment by separating the age group from 15~29 years old. The data used in the analysis was the 9th to 20th data of the Korea Labor Panel Survey. The youth unemployment rate and employment rate were referred to the Economically Active Population Survey of Statistics Korea. The analysis subject was limited to young people who are currently performing economic activities, and the analysis method used multi-level logit model. The main results are summarized as follows. First, the lower the unemployment rate and the higher the employment rate, the younger people tend to enter their own businesses on the structural level. Second on the individual level, young people who possess enough financial capital or pursuit personal aptitude or interest tend to enter self-employment. However, there are no statistical effects of human capital and entrepreneur capital.

• The Korean Journal of Emergency Medical Services
• /
• v.16 no.1
• /
• pp.7-18
• /
• 2012

Purpose: The purpose of this study is to help care workers to do their best as first respondents by analysing their recognition, knowledge, and self-efficacy on basic CPR (cardiopulmonary resuscitation) that is directly connected to the lives of patients and thus their education and methods can be improved for their positive basic lifesaving work. Method: For this purpose 360 structured questionnaires were used to the subjects in the eastern area of Jeonnam province from June 20 to July 4, 2011. Of these questionnaires 217 were used excluding 113 incomplete, 27 error, and 3 male ones. The collected data were analysed by the real number, the percentage, the average, the standard deviation, t-test, ANOVA, and Tukey with SPSS WIN 18.0. Results: 1. In the view of subjects, those aged over 51 accounted for 96(44.2%) as the majority, high school graduates, 95(43.8%), worked for 1 or more than 1 year-less than 2 years, 66(30.4%), experienced to see persons collapsed losing their consciousness, 46(21.2%), took the education, 184(85.7%), had 1 session of education, 80(43%), got the last education for 2 or more than 2 years 68(37%), and practiced through mannequin for the education aids, 86(46.7%). 2. There was significant difference in the view of recognition with the length of work (p=.010) and experienced to see persons collapsed losing their consciousness (p=.020), in the view of knowledge with academic background (p=.040) and the length of work, and in the view of self-efficacy with academic background (p=.002), the length of work (p=.010) and experienced to see persons collapsed losing their consciousness (p=.000). 3. There was significant difference in the session of education (p=.000), last education (p=.025) and education aids for basic CPR. Self-efficacy had significant difference according to the session of education for basic CPR (p=.001) and the time of education (p=.000). 4. There was correlation between recognition and self-efficacy (r=.41). The higher the recognition is, the better the self-efficacy improves. However the correlation between knowledge and self-efficacy was so low that the former did not have influence on self-efficacy. Conclusions: It needs to offer education to the lifesaving workers based on their experiences. If there is education more than 2 sessions in a year with mannequin and the simulation providing sufficient hours, care workers' recognition would be increased resulting in higher self-efficacy and thus they could keep the role of active lifesaving worker at the first practical site.

• Journal of Service Research and Studies
• /
• v.13 no.3
• /
• pp.20-38
• /
• 2023

Recently, car sharing has shown the most remarkable growth among sharing economy services. In the process of analyzing the intention to reuse the car sharing service, this study tried to reflect the unique characteristics of the service, which consists of non-face-to-face self-service, such as reservation, approval, handover, inspection, and return of the vehicle. Specifically, in addition to the perceived benefits and the perceived risks, we considered 'information quality' as a platform characteristic and 'self-efficacy' as a personal characteristic. To collect data, an online survey was conducted on adults with experience in car sharing, and a total of 320 responses were used for analysis. As a result of analyzing the structural equation model, it was found that information quality and self-efficacy increased the perceived benefits of services, and the higher the information quality, the higher the self-efficacy. On the other hand, the role of information quality and self-efficacy in lowering perceived risks was insignificant, and the intention to reuse services was more affected by perceived benefits than perceived risks. As a result of further analysis using Process Macro, it was found that the effect of self-efficacy on reuse intention was mediated by perceived benefits. It was analyzed that the indirect effects of information quality on reuse intention through perceived benefits or self-efficacy were all significant. These results suggest that providing timely, sufficient, and easy-to-understand information required by users on the platform improves self-efficacy and increases service reuse intention. In order to increase the number of service users, it is important for service providers not only to provide promotional activities such as offering attractive prices, but also to provide high-quality information so that users can use it more easily.