• 대한기계학회논문집A
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• 제20권1호
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• pp.154-162
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• 1996

Ball screws are commonly used in linear motion feeding systems of various machine tools and automated systems. They are known to have relatively little backlash, high precision and efficiency compared to ordinary lead screws. Furthermore, the effectiveness of ball screw has made it the preferred choice of many newly developed high speed precision feeding units. The motivation of this work is to establish the groove edsigh basis of ball screws for the reduction of contact fatigue failure. In most instances, fatigue failure between ball and shaft groove is due to excessive contact pressure. Especially, the excessive load is causative of plastic flow below the contact surface, which can contribute to surface failure. But, in spite of small load, if groove conformity rate is large, contact pressure is increased and internal shear stress reach the yield value of the material. In such a point, the authors deal with design procedure for deciding the permissible conformity rate of a ball screw groove with the computational evaluation of contact pressure and maximum shear stress.

• 대한수학교육학회지:수학교육학연구
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• 제8권2호
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• pp.663-677
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• 1998

The development of Science and Technology and the social change require new paradigm in Education. In a traditional paradigm, learners have been regarded as a passive being and knowledge could be transmitted to learner. But within this paradigm, it is difficult to confront the social change and to develop problem solving skills in various context. This results in a new, alternative perspective, Constructive paradigm. As an alternative to the traditional settings, Constructive paradigm emphasizes the learner centered instruction. The reform movement in mathematics education including NCTM's standards revolves around this paradigm and the open education movement in our educational system is based on it. Open education values learner's interest, autonomy and internal motivation in learning. However, open education has been misunderstood by most of the teachers. It should be understood as the change of paradigm. In this study, as a way of helping students connect mathematics to their everyday lives and construct meaningful mathematical knowledge and concept, mathematical modelling is suggested. It consists of posing and specifying the real problem, formulation and constructing a mathematical model, analyzing and solving a mathematical problem. interpreting the solution and comparing with reality and communicating results. In this process, technology like computer can be a powerful tool. It can help students explore various problems more easily and concretely.

• 복식문화연구
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• 제8권1호
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• pp.87-101
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• 2000

The purpose of study is explaining the Historicism as a result of compromise, historical eclecticism, between historical things and current cultural background instead of regarding it as an imitation from the past. It means that external factors in history help internal esthetic value surface out as costume. Fashion s history is more than the classified thing according to the appearance with the changes of the times. Intrinsic cultural elements should be added in creating new fashion. One of the different features between Modernism and Post-modernism. When coming to the period of Post-modernism, it connected with the historical factors to make something new by fragmenting, magnifying, or minimizing them. This is calles 'Historicism'in the world of art. It revived the past, not the past itself, in new ways : quotation, reuse, metaphor, and mixture. To represent the image, parody, pastiche, or bricolage was usually used. In post-modernism fashion, parody is a technique for imitating the past or the preceding forms with artists'own critical points of view. This technique gives us shock or surprise by using satirical, ironical or paradoxical expressions. pastiche shares the same part with parody in imitating particular or unique style, and it can be renamed empty parody, because it doesn't have any hidden motivation or satirical impulse. bricolage is a mixture of quotations from other works. It contains fragments that deepen the image. Like the techniques uttered above, the revival of history through parody, pastiche or bricolage is historical eclecticism and it is included in Historicism.

• 경영과정보연구
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• 제6권
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• pp.267-290
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• 2001

Today's firms are experiencing severe competition and lots of change under uncertainty of the future. In order to survive in rapidly changing environment, companies have steadily adopted information technology(IT) environment. The advancement of information technology allows people to access information and knowledge resources without the limitation of time and location through internet. Many organizations have developed their own information systems not only for internal efficiency but also for effectiveness of external customer services. This study is intended to provide a theoretical framework of information and knowledge and their relationship, that the infusion of powerful information networks into business environments is beginning to have a profound a significant difference of the nature between information satisfaction and accounting information system(AIS) in the business activity. This paper is to maximize the efficiency of university libraries human resources management by determining the followings the relationship between the level of information technology implement and the job satisfaction of the librarian, the main factors that affect job satisfaction. Questionnaire was sent to 120 companies from 20 corporations chosen by random sampling and the methods of ANOVA, T-test, and correlation analysis were used. The results of the analysis are as follows; 1) There is a unsignificant difference in the level of information satisfaction by accounting information system and the motivation factor according to the level of implementation of IT. 2) There is a relatively high in a significant difference in information satisfaction by the level of net income. 3) There is high a significant difference is shown in the accounting years while implementing the IT and information satisfaction.

• 동아시아식생활학회지
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• 제26권1호
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• pp.11-24
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• 2016

This study was conducted to analyze the nutrition education and diet contents presented in toddler picture books. The study was conducted from August to October 2015 and examined five of Korea's major online bookstores. Finally, we analyzed 296 books, and 67 books contained dietary life contents. The contents of nutrition education were mainly about eating an even diet and keeping good table manners. However, contents of specific, practical dietary guidelines were not included. Therefore, it is recommended to eat a variety of vegetable side dishes at every meal, eat on time and not eat salty, sweet and fatty foods. Most parenting styles on feeding practice for nutrition education were dictatorial. To make parenting styles more effective, the parents' style should be more desirable. In order to provide internal motivation for toddlers and have a positive education effect, teaching methods on eating using picture books should be presented in a positive way. Food often appearing in picture books were vegetables, but green leafy vegetables were hardly observed. Foods that frequently showed up in picture books were pastries, which reflect Westernized food culture.

• 한국지역사회생활과학회지
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• 제22권3호
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• pp.455-469
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• 2011

The purpose of this study was to find out how follow-up activities of reading picture books influenced infants' language and socio-emotional development. Subjects of this study were 27 2-year-old infants at public day care centers in Busan. After implementing follow-up activities of reading picture books for 8 weeks, this study tried to investigate changes in infants' language and socio-emotional development. Results of this study are as follows. First, follow-up activities of reading pictures have brought positive impacts on infants' language ability. Results indicate a positive influence on infants' expressive and acceptive language ability. Second, follow up activities have also enhanced infants' socio-emotional development. Sepcifically, they have been effective in improving infants' low-level socio-emotional development such as 'internal control', 'peer interaction', and 'achievement motivation'. It is expected that the follow-up activities developed by this research would help to enhance infants' language development and socio-emotional development.

• 수산해양교육연구
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• 제28권5호
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• pp.1209-1219
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• 2016

In knowledge based society, lifelong learning is increasing in order to meet educational needs of adult learners. Credit Bank system which is credited by individual experience, learning and qualifications are also emphasized for continuing learning participation. However, in spite of the importance of concern in the Credit Bank System, adult learners expectation and value are not high. The purpose of this study is to analyze participation valence and learning flow of adult learner in the Credit Bank System. The result of this study is summarized as follows: first, adult learners participated in the Credit Bank System to get new knowledge and skill based on internal and external motivation and requirement not involved with individual degree. Second, adult learners participating in the Credit Bank System are experiencing learning flow realizing that behavior of participation is compensated, adult learners are concentrating and feeling with satisfaction and pleasure to study. Third, participation in the Credit Bank System based on adult learner's own right learning requirement have been analyzed as it has a positive effect to the learning flow and have indicated that adult learners having high level of valence experience, recognition immersion, behavioral devotion, and egoistic immersion. Based on the conclusion, further studies are suggested.

• Smart Structures and Systems
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• 제18권2호
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• pp.335-354
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• 2016

This contribution presents an extended one-dimensional theory for piezoelectric beam-type structures with non-ideal electrodes. For these types of electrodes the equipotential area condition is not satisfied. The main motivation of our research is originated from passive vibration control: when an elastic structure is covered by several piezoelectric patches that are linked via resistances and inductances, vibrational energy is efficiently dissipated if the electric network is properly designed. Assuming infinitely small piezoelectric patches that are connected by an infinite number of electrical, in particular resistive and inductive elements, one obtains the Telegrapher's equation for the voltage across the piezoelectric transducer. Embedding this outcome into the framework of Bernoulli-Euler, the final equations are coupled to the wave equations for the longitudinal motion of a bar and to the partial differential equations for the lateral motion of the beam. We present results for the wave propagation of a longitudinal bar for several types of electrode properties. The frequency spectra are computed (phase angle, wave number, wave speed), which point out the effect of resistive and inductive electrodes on wave characteristics. Our results show that electrical damping due to the resistivity of the electrodes is different from internal (=strain velocity dependent) or external (=velocity dependent) mechanical damping. Finally, results are presented, when the structure is excited by a harmonic single force, yielding that resistive-inductive electrodes are suitable candidates for passive vibration control that might be of great interest for practical applications in the future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권10호
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• pp.3793-3814
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• 2021

Most secure solutions like cryptography are software based and they are designed to mainly deal with the outside attacks for traditional networks, but such soft security is hard to be implemented in wireless sensor networks to counter the inside attacks from internal malicious nodes. To address this issue, reputation has been introduced to tackle the inside malicious nodes. Reputation is essentially a stimulating mechanism for nodes' cooperation and is employed to detect node misbehaviors and improve the trust-worthiness between individual nodes. Among the reputation models, binomial distribution based reputation has many advantages such as light weight and ease of implementation in resource-constraint sensor nodes, and accordingly researchers have proposed many insightful related methods. However, some of them either directly use the modelling results, apply the models through simple modifications, or only use the required components while ignoring the others as an integral part of the whole model, this topic still lacks a comprehensive and systematical review. Thus the motivation of this study is to provide a thorough survey concerning each detailed functional components of binomial distribution based reputation for wireless sensor networks. In addition, based on the survey results, we also argue some open research problems and suggest the directions that are worth future efforts. We believe that this study is helpful to better understanding the reputation modeling mechanism and its components for wireless sensor networks, and can further attract more related future studies.

• 의학교육논단
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• 제24권3호
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• pp.215-230
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• 2022

The purpose of this study was to explore the psychosocial characteristics of academically maladjusted students and the College's current status regarding academic maladjustment based on 4-year medical student cohort data collected from 2018 to 2021 and through interviews with 10 medical education experts using the integrated research method. This study included 223 students who consented to inclusion in the student cohort and participated in the emotional behavior test and college adaptability test of whom 65 students experienced academic maladjustment. Academically maladjusted students had significantly higher scores for social stress, anxiety, sense of inadequacy, attention, hyperactivity, and school maladjustment, and significantly lower scores for relationships with parents, interpersonal relationships, self-esteem, self-confidence, and self-strength. Academic and social integrity, emotional stability, university satisfaction, and university service satisfaction were all significantly lower in the academically maladjusted students than in the non-maladjusted group. The expert interviews indicated that academic maladjustment was mainly recognized as a personal problem, with causes such as lack of motivation and learning methods, vulnerability to stress, lack of social relationships and alienation, lack of support from the family, and insufficient resilience. Systematic support other than counseling for academically maladjusted students is required, and an early diagnosis and preventive intervention are important.