• Smart Structures and Systems
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• 제20권3호
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• pp.285-301
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• 2017

This paper presents the design and the application of a new self-powered hybrid electromagnetic damper that can harvest energy while mitigating the vibration of a structure. The damper is able to switch between an energy harvesting passive mode and a semi-active mode depending on the amount of energy harvested and stored in the battery. The energy harvested in the passive mode resulting from the suppression of vibration is employed to power up the monitoring and electronic components necessary for the semi-active control. This provides a hybrid control capability that is autonomous in terms of its power requirement. The proposed hybrid circuit design provides two possible options for the semi-active control: without energy harvesting and with energy harvesting. The device mechanism and the circuitry that can drive this self-powered electromagnetic damper are described in this paper. The parameters that determine the device feasible force-velocity region are identified and discussed. The effectiveness of this hybrid damper is evaluated through a numerical simulation study on vibration mitigation of a bridge stay cable under wind excitation. It is demonstrated that the proposed hybrid design outperforms the passive case without external power supply. It is also shown that a broader force range, facilitated by decoupled passive and semi-active modes, can improve the vibration performance of the cable.

• 한국정밀공학회지
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• 제16권1호통권94호
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• pp.253-264
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• 1999

Most autonomous mobile robots view only things in front of them, and as a result, they may collide with objects moving from the side or behind. To overcome this problem. an Active Omni-directional Range Sensor System has been built that can obtain an omni-directional range data through the use of a laser conic plane and a conic mirror. Also, mobile robot has to know its current location and heading angle by itself as accurately as possible to successfully navigate in real environments. To achieve this capability, we propose a self-localization algorithm of a mobile robot using an active omni-directional range sensor in an unknown environment. The proposed algorithm estimates the current position and head angle of a mobile robot by a registration of the range data obtained at two positions, current and previous. To show the effectiveness of the proposed algorithm, a series of simulations was conducted and the results show that the proposed algorithm is very efficient, and can be utilized for self-localization of a mobile robot in an unknown environment.

• 아동학회지
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• 제32권6호
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• pp.141-155
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• 2011

This study investigated whether middle school and high school students' coping strategies and positive thinking patterns moderate the negative effects of self-discrepancies on maladjustive emotions represented by depression and anxiety. The study participants consisted of 308 middle school students and 301 high school students from schools from metropolitan areas in Korea. The results of this study were as followed. First, the high school students reported higher scores in terms of depression, anxiety, and active coping strategies than the middle school students, while the middle school students reported higher scores in terms of positive thinking than the high school students. Second, the high school students' active coping strategies and positive thinking patterns moderated the negative effects of self-discrepancies on maladjustive emotions. These results indicate that both middle and high school students' self-discrepancies negatively affected maladjustive emotions, whereas active coping strategies and positive thinking patterns positively affected maladjustive emotions. In addition, active coping strategies and positive thinking patterns had a moderating effect only among the high school students.

• 한국직업건강간호학회지
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• 제17권1호
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• pp.34-44
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• 2008

Purpose: This study was conducted to find out the effects of self-efficacy on job stress symptoms and coping strategies depending on perceived job stress. Method: The subjects were 447 workers employed in a manufacturing company. Demographic characteristics, self-efficacy, job stress, job stress symptoms and coping strategies were assessed by a self-administered questionnaire. Each envelope to keep the secret sealed completed questionnaires. Result: Job stress and job stress symptoms in workers with a high level of self-efficacy were lower than those of a low level of self-efficacy. Active coping strategies in workers with a high level of self-efficacy group were higher than those of a low level of self-efficacy. In multiple regression analysis, job stress symptoms were significantly higher in increasing job stress, increasing self-efficacy, office workers, manager group and increasing age. Active coping strategies were significantly higher in increasing self-efficacy, increasing career, males and decreasing job stress. Whereas passive coping strategies were significantly higher in females, increasing job stress and increasing self-efficacy. Conclusion: This study suggests that self-efficacy is a significant factor on job stress, job stress symptoms and coping strategies. Therefore, developing a job stress management program to increase self-efficacy and verifying its effects are needed.

• 정신신체의학
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• 제5권1호
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• pp.63-72
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• 1997

For the purpose of examining the relationship between perceived stress, vulnerability variables, and somatization tendency, the self-report questionnaires of perceived stress, styles of stress coping(passive and active copings), self-perception, gender, and somatization tendency were administered to university entrants(n=2,024). The results were as follows: 1) Perceived stress, styles of stress coping(passive and active copings), self-perception, and gender accounted for 15.56% of the total variance in somatization tendency. As a result of comparing the relative contributions of all predictor variables to somatization tendency, the highest was perceived stress, and the next in order were passive coping style, self-perception, and gender, whereas direct effect of active coping style was not significant. 2) The two-way and three-way interaction effects of perceived stress X vulnerability variables were not significant. 3) The two-way and three-way interaction effects of gender X psychosocial variables were not significant. To conclude, perceived stress and vulnerability variables independently contribute to somatization tendency in university entrants, and furthermore it is suggested that vulnerability variables as well as perceived stress must be considered to account for somatization tendency.

• 한국보육지원학회지
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• 제19권3호
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• pp.41-57
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• 2023

Objective: The objective of this study is to classify the personality types of early childhood teachers and examine the variations in teacher self-efficacy and play support based on these personality types. Methods: The subjects of this study consisted of 302 early childhood teachers responsible for children aged 3 to 5 years old. The collected data were analyzed using cluster analysis and analysis of covariance. Results: Early childhood teachers were categorized into four types: the "sensitive group" (29%), the "conservative group" (10%), the "passive group" (28%), and the "active group" (34%). Significant differences in mean scores were observed for teacher self-efficacy and play support across these personality types. Notably, the active group demonstrated the highest levels of both teacher self-efficacy and play support. Consequently, the active group emerged as the most effective and functional personality type among early childhood teachers. Conclusion/Implications: This study emphasized the significance of early childhood teachers' personality types in their teaching practices, underscoring the importance of developing in-service and pre-service teacher education programs that take into account these personality types.

• 한국기계가공학회지
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• 제10권5호
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• pp.13-19
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• 2011

In this paper, the active monitoring and control system is developed. This system can monitor the status of high the speed spindle in real time during its processing, and can analyze its influence of dimensional accuracy and processing if any, and can control the machining condition to realize the machining system equipped with active monitoring and self-diagnostic features. Machining experiment was performed on 3 materials Al, Brass and S45C in order to derive the relation between active monitoring and control algorithm by the machining load. In addition, we measured surface roughness of processing specimen along with the data change of spindle rotating speed and conveying speed according to variation of machining load. Based on these experiments, we derived relations for each material that can be applied to the control algorithm to allow self control of the rotating speed and conveying speed according to the machining load.

• 대한수학교육학회지:학교수학
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• 제1권1호
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• pp.123-133
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• 1999

For an appropriate assessment in mathematics, students should play an active role in their learning by becoming aware of what they have learned in mathematics and by being able to assess their attainment of mathematical knowledge. The process of actively examining and monitoring students' own progress in learning and understanding of their mathematical knowledge, process, and attitude is called self-assessment, Researchers in mathematics education have found some important facts about the meta-cognitive process which is related to self-assessment : i. e. meta-cognition progress is composed of being aware of ones' own personal thinking of content knowledge and cognitive process(self-awareness) and engagement in self-evaluation. Tipical method for self-assessment in mathematics developed upon above finding about meta-cognitive progress is describing about students' knowledge and their problem solving strategies. In the beginning of the description in mathematics about themselves, students are required to answer which part they know and which part they don't know. Self-assessment of students' attitudes and dispositions can be just as important as assessment of their specific mathematical abilities. To make the self-assessment method a success, teachers should let students' have confidence and earn their cooperation by let them overcoming fear to be known the their ability to other students. In conclusion, self-assessment encourages students to assume an active role in development of mathematical power. For teachers, student self-assessment activities can provide a prism through which the development of students' mathematical power can be viewed.

• 한국간호교육학회지
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• 제9권1호
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• pp.103-114
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• 2003

The purpose of this study is to test the motivation, attitude of voluntary service and self-esteem of college students. Therefore it can give the fundamental data of the institutionalization plan and to find the activative methods of voluntary system. This study is based on the questionaire, that was consisted of motivation, attitude of voluntary service and self-esteem. For this study, 223 college students were answered. The data was collected from 10th to 30th September 2002. The results of this study are as follows : 1. $\cdot$The mean score on the motivations scale of voluntary service was $3.221{\pm}0.42$. $\cdot$The mean score on the attitudes scale of voluntary service was $3.28{\pm}0.49$. $\cdot$The mean score on the self-esteem was $2.56{\pm}0.46$. 2. There were significant differences between voluntary service was self motivated(F= 11.12, p= 0.000), the students who will participate very active in voluntary service aftergraduation(F= 11.12, p= 0.000), and the motivations of voluntary service. 3. There were significant differences between the students who will participate very active in voluntary service after graduation (F= 8.23, p= 0.000) and the attitudes of voluntary service. 4. There were significant differences between voluntary service was self motivated (F=4.69, p= 0.004), the students who will participate very active in voluntary service after graduation(F=2.49, p=0.045), the parents who have the experience of voluntary service(F= 5.03, p= 0.026), the students who have the experience of voluntary service before college entrance. 5. There was positively significant correlation between the motivations of voluntary service and the attitudes (r= .693, P=0.01), the attitudes and self-esteem (r= .326, p=0.01), and the motivations of voluntary service and self-esteem (r= .305, p=0.01).

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.114-114
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• 2000

In this paper a self-tuning modified skyhook control for the semi-active suspension systems is investigated. The damping force generation mechanism is modeled We consider a 2 DOF time-varying quarter car model that permits parameter variations of the sprung mass and suspension spring coefficient. The modified skyhook control algorithm proposed in this paper requires only the measurement of body acceleration. The absolute velocity of the sprung mass and the relative velocity of the suspension deflection are estimated by using integral filters, according to parameter variations. The skyhook gains are designed in such a way that the body acceleration and the dynamic tire force are optimized. An ECU prototype will be discussed