• 한국초등과학교육학회지:초등과학교육
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• 제35권2호
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• pp.243-252
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• 2016

The purpose of this study was to analyze affective characteristics and the demands of elementary science gifted students on gifted educations in urban and rural areas. The subjects were 196 science gifted students. The survey questionnaires were consisted of self-esteem, interests in science, scientific attitudes, and demands regarding gifted classes. The results of this study were as follows. First, self-esteem and interests in science, particularly interests toward science, toward science learning, toward science related careers, in urban gifted students were higher than those in rural areas. Whereas interests toward science activities and science anxiety of science gifted students in rural areas were significantly higher than those in urban area. Furthermore, scientific attitudes of science gifted students in urban area were higher than rural those in open-mindedness, critical-mindedness, voluntariness, creativity, whereas science gifted students in rural areas were higher than urban those in cooperation. Second, for the analysis on demands regarding class contents and methods, 'teaching content that challenges and exciting stimuli' of science gifted students in rural areas were significantly higher than those in urban area. Third, for the analysis on demands regarding educational environments, 'satisfaction with class materials provided by gifted classes' of gifted students in urban area were higher than those in rural area.

• 제어로봇시스템학회논문지
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• 제2권4호
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• pp.306-311
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• 1996

This paper discusses the maintenance of the water level of steam generators at its programmed value. The process, the water level of a steam generator, has the nonminimum phase property. So, it causes a reverse dynamics called a swell and shrink phenomenon. This phenomenon is severe in a low power condition below 15 %, in turn makes the start-up of the power plant too difficult. The control algorithm used here incorporates a pole-assignment scheme into the minimum variance strategy and we use a parallel adaptation algorithm for the parameter estimation, which is robust to noises. As a result, the total control system can keep the water level constant during full power by locating closed-loop poles appropriately, although the process has the characteristics of high complexity and nonlinearity. Also, the extra perturbation signals are added to the input signal such that the control system guarantee persistently exciting. In order to confirm the control performance of a proposed pole-assignment self-tuning controller we perform a computer simulation in full power range.

• 전기의세계
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• 제18권3호
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• pp.34-39
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• 1969

종래 사용되어온 교류발전기의 자동전압조정기는 직류여자기의 계자전류를 제어함으로써 교류 발전기의 단자전압을 일정하게 유지하는 방식이었다. 이경우 정정시의 전압변동을 적게하는 것은 비교적 용이하지만 급격한 부하변동에 대해서는 불경하였다. 즉 발전기에 급히 부하가 걸리면 발전기의 특성에 의하여 결정되는 전압이 순간적으로 떨어지고 또 발전기에는 복권작용이 없고 직류여자기및 제어장치의 시정수에 의한 조정작용의 시간적 늦음이 있기때문에 발전기의 전압은 더욱 강하한다. 이 전압강하의 방지책으로 발전기를 필요이상 크게하여 단종비를 크게하고 또 속응여자를 행하고 있다. 그리고 발전기의 부하가 유도전동기이 가능한 것은 소용량에 한하고 거의 모두 감압기동을 하고 있었다. 이 난점을 보상하기 위해 주회로전류에 의한 복권특성을 갖는 자여자교류발전기가 개발되어 왔으며 근래에는 S.C.R (Silicon Controlled Rectifier)의 발달에 따라 자기증폭기식에서 Transistor-Thyristor식으로 변천하고 있다. 여기서는 자여자발전기를 이용한 정전압장치부 자려자교류벌전기 75KVA에 대한 특성을 소개하고자 한다.

• 대한공업교육학회지
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• 제30권1호
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• pp.120-132
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• 2005

The major purpose of this study was to provide a basic model of mobile guide system for visitor's individual learning, self-regulated learning in a museum. System model realized by this study was as follows; 1) This system distributed exhibit information to tourists in place of existing audio guides or curators. Using wireless communications, the PDA automatically delivered information about the exhibit. The artistic and visual displays maximized effective and quick transmission of information to the user. 2) It made visiting a museum fun, exciting and entertaining. With the PDA guide the museum visitor can interact with detailed descriptions of exhibits, videos and images. The museum visitor, can also play a quiz game, take photos, record voices and send e-mail.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.602-603
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• 2014

A gearbox can be regarded as a self-exciting dynamic system, which has a vibration source. Transmission error (TE) is considered to be an main excitation source for gear noise and vibration. The TE excitation is transmitted through the gears, shafts, bearings, and housings. Thus, an experimental approach to each mechanical parts is useful in order to understand and evaluate the dynamic behaviour of a gearbox. This study is focused on the transmission and vibration characteristics of a helical gear system in development stage. In addition, by considering the tolerance factors and resonance characteristics, the vibration response of actual dynamic system is analysed.

• Molecules and Cells
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• 제42권9호
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• pp.617-627
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• 2019

Brain organoids are an exciting new technology with the potential to significantly change our understanding of the development and disorders of the human brain. With step-by-step differentiation protocols, three-dimensional neural tissues are self-organized from pluripotent stem cells, and recapitulate the major millstones of human brain development in vitro. Recent studies have shown that brain organoids can mimic the spatiotemporal dynamicity of neurogenesis, the formation of regional neural circuitry, and the integration of glial cells into a neural network. This suggests that brain organoids could serve as a representative model system to study the human brain. In this review, we will overview the development of brain organoid technology, its current progress and applications, and future prospects of this technology.

• 대한영양사협회학술지
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• 제17권2호
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• pp.130-141
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• 2011

This study was conducted to develop a nutrition education workbook to improve picky eating in children and to evaluate the effect of nutrition education using this developed workbook. The developed workbook focused on 2nd and 3rd grade students and consisted of five units. The contents included: multi-grain, vegetables (2 units), fish, and milk. The activities, including observation, and learning the roles and names of the foods, were developed mainly to increase motivation for eating a balanced diet. This workbook was developed from April to December 2008, and was applied at 15 elementary schools containing 1,674 students from April to September 2009 in Changwon City, Korea. We evaluated changes in knowledge before and after education on nutrition, eating behavior, dietary habits, and educational activities using self-administered questionnaires. The children demonstrated significant improvements in nutritional knowledge (P<0.001), eating behavior (P<0.001), and dietary habits (P<0.001). Most of the children answered that the education program was helpful and exciting. Based on these results, we believe that the developed workbook is suitable for children picky eaters, and hope it will be used in the field of child nutrition education.

• 의학교육논단
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• 제15권2호
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• pp.82-86
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• 2013

Medical students can choose to pursue any of a large number of specialties. This diversity reflects exciting opportunities, yet it also present significant challenges, such as providing medical students with adequate resources and guidance to help them to make informed career decisions. Additionally, because the medical internship will be abolished in the near future, many Korean medical schools have recently focused on implementing a career planning and advising program. This paper describes the Careers in Medicine (CiM) program offered by the Association of American Medical Colleges as a framework for other schools to adopt or adapt as they consider the best ways to address the career counseling needs of their own students. CiM is a comprehensive career planning program that provides students with the skills, information, and resources to choose a specialty and residency program that meets their career goals. CiM follows a four-year, four-step career planning process including self-understanding, exploring a variety of medical careers, and finally choosing a specialty. The CiM program has been evaluated as successful because of widespread participation and positive feedback from medical students. The information in this study can be used to develop a formal career advising program throughout the four years of medical school.

• Journal of Power Electronics
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• 제5권3호
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• pp.198-205
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• 2005

The mechanical system of a drive can often be modeled as a two- or three-mass-system. The load is coupled to the driving motor by a shaft able to perform torsion oscillations. For the automatic tuning of the control, it is necessary to know the mathematical description of the system and the corresponding parameters. As the manpower and setup-time necessary during the commissioning of electrical drives are major cost factors, the development of self-operating identification strategies is a task worth pursuing. This paper presents an identification method which can be utilized for the assisted commissioning of electrical drives. The shaft assembly can be approximated as a two-mass non-rigid mechanical system with four parameters that have to be identified. The mathematical background for an identification procedure is developed and some important implementation issues are addressed. In order to avoid the excitation of the system with its natural resonance frequency, the frequency response can be obtained by exciting the system with a Pseudo Random Binary Signal (PRBS) and using the cross correlation function (CCF) and the auto correlation function (ACF). The reference torque is used as stimulation and the response is the mechanical speed. To determine the parameters, especially in advanced control schemes, a numerical algorithm with excellent convergence characteristics has also been used that can be implemented together with the proposed measurement procedure in order to assist the drive commissioning or to achieve an automatic setting of the control parameters. Simulations and experiments validate the efficiency and reliability of the identification procedure.

• 과학교육연구지
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• 제37권1호
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• pp.68-78
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• 2013

그동안 예술활동과 과학교육을 통합하는 연구는 학생들의 예술교육에 직접적으로 관여하는 유아교육과 초등교육분야에서는 꾸준히 진행되어 왔다. 그러나 일부 과학교육자들은 STEAM 교육을 통해 디자인의 원리를 이용하여 산출물을 시각화하거나 실험결과를 표현하는데 주된 관심을 보였다. 이에 미술활동이 과학교육과 통합된 수업을 실시할 때, 학생들의 능력 변화에 대한 연구가 필요하다. 그래서 이 연구의 목적을 미술활동과 연계한 과학실험활동이 초등학생들의 자기주도학습능력과 창의적 성격에 미치는 영향을 알아보는 것으로 하였다. 이 연구는 창원에 있는 C초등학교 4학년 30명(남 16, 여 14)을 대상으로 하였다. 수업자료는 2007 개정 교육과정 초등과학교과서와 '신나는 과학을 만드는 사람들' 실험자료집에서 추출되었다. 수업처치는 5가지 주제에 대해 10차시로 진행되었으며, 사전-사후검사로 G-TAGAS가 실시되었다. 그 결과 미술활동과 연계한 과학실험활동은 자기주도학습능력과 창의적 성격에서 유의미한 향상이 있었다.