Optoelectrofluidic field separation based on light-intensity gradients     

Sanghyun Lee  Hyun Jin Park  Jin Sung Yoon    Kwan Hyoung Kang 《Biomicrofluidics》2010,4(3)

Optoelectrofluidic field separation (OEFS) of particles under light -intensity gradient (LIG) is reported, where the LIG illumination on the photoconductive layer converts the short-ranged dielectrophoresis (DEP) force to the long-ranged one. The long-ranged DEP force can compete with the hydrodynamic force by alternating current electro-osmosis (ACEO) over the entire illumination area for realizing effective field separation of particles. In the OEFS system, the codirectional illumination and observation induce the levitation effect, compensating the attenuation of the DEP force under LIG illumination by slightly floating particles from the surface. Results of the field separation and concentration of diverse particle pairs (0.82–16 μm) are well demonstrated, and conditions determining the critical radius and effective particle manipulation are discussed. The OEFS with codirectional LIG strategy could be a promising particle manipulation method in many applications where a rapid manipulation of biological cells and particles over the entire working area are of interest.  相似文献   

Education in the New Millennium: The Case for Design‐Based Learning     

Hyun‐Kyung Lee  Mark Breitenberg 《The International Journal of Art & Design Education》2010,29(1):54-60

This article focuses on current examples of project or design‐based learning at the secondary school level in the context of the increasing importance of creativity and innovative thinking in the twenty‐first century. The authors argue that students today learn more effectively in pedagogical practices that emphasise holistic thinking, active learning, visual media and problem‐solving. Design‐based learning presents new ways for realising long‐term goals and learning outcomes. The purpose of this article is to investigate best practices of design education in the community and to propose instructional resource examples on design to K‐12 school teachers. This article points out the importance of systemised process for the work of design‐based teachers and learners, addresses the study of design as a subject of investigation and a mode of inquiry that engages a variety of student learning styles and makes direct connections between subjects and problem‐solving in daily life. Our belief is that the case studies explored in this article represent the seeds of a new model of education based on creative and applied learning. The exemplar communities chosen for onsite research are the education department of the Cooper‐Hewitt National Design Museum in New York City and the Art Center College of Design in Pasadena, California, USA.  相似文献   

Advanced stability criteria for linear systems with time-varying delays     

M.J. Park  O.M. Kwon  J.H. Ryu 《Journal of The Franklin Institute》2018,355(1):520-543

This paper investigates a stability problem for linear systems with time-varying delays. By constructing suitable augmented Lyapunov–Krasovskii functionals, improved stability criteria under various conditions of time-varying delays are derived within the framework of linear matrix inequalities (LMIs). Moreover, to reduce the computational burden caused by the non-convex term including h²(t), how to deal with it is applied by estimating it to the convex term including h(t). Finally, three illustrative examples are given to show the effectiveness of the proposed criteria.  相似文献   

Guiding Attention Aids the Acquisition of Anticipatory Skill in Novice Soccer Goalkeepers     

Donghyun Ryu  Seonjin Kim  Bruce Abernethy  David L. Mann 《Research quarterly for exercise and sport》2013,84(2):252-262

Purpose: The ability to anticipate the actions of opponents can be enhanced through perceptual-skill training, though there is doubt regarding the most effective form of doing so. We sought to evaluate whether perceptual-skill learning would be enhanced when supplemented with guiding visual information. Method: Twenty-eight participants without soccer-playing experience were assigned to a guided perceptual-training group (n = 9), an unguided perceptual-training group (n = 10), or a control group (n = 9). The guided perceptual-training group received half of their trials with color cueing that highlighted either the key kinematic changes in the kicker's action or the known visual search strategy of expert goalkeepers. The unguided perceptual-training group undertook an equal number of trials of practice, but all trials were without guidance. The control group undertook no training intervention. All participants completed an anticipation test immediately before and after the 7-day training intervention, as well as a 24-hr retention test. Results: The guided perceptual-training group significantly improved their response accuracy for anticipating the direction of soccer penalty kicks from preintervention to postintervention, whereas no change in performance was evident at posttest for either the unguided perceptual-training group or the control group. The superior performance of the guided perceptual-training group was preserved in the retention test and was confirmed when relative changes in response time were controlled using a covariate analysis. Conclusions: Perceptual training supplemented with guiding information provides a level of improvement in perceptual anticipatory skill that is not seen without guidance.  相似文献   

Components of Conceptual Ecologies   总被引：1，自引：0，他引：1  

Hyun Ju Park 《Research in Science Education》2007,37(2):217-237

The theory of conceptual change is criticized because it focuses only on supposed underlying logical structures and rational process processes, and lacks attention to affective aspects as well as motivational constructs in students’ learning science. This is a vast underestimation of the complexity and diversity of one’s change of conceptions. The notion of conceptual ecology provides a context for understanding individuals’ conceptual change learning, as it is the environment through which all information is interpreted. This research investigated how high school students’ statements, made in answering questions, reflect selected components of their conceptual ecologies. Data for this study was collected from six interviews in which seven students took part. The data also include the science teacher’s profiles of each student, the students’ personal journals, their assignments, and their examinations and answers in class. The analysis presented will here include only those components that were represented in the discourse of the seven high school students who were interviewed. When students were asked questions, there was evidence of the engagement of the various components of conceptual ecologies. These components include: epistemological commitments, metaphysical beliefs, the affective domain and emotional aspects, the nature of knowledge, the nature of learning, the nature of conceptions, and past experience. Evidence from this study suggests that these components might function as constraints to learning. This study contributes to the field by expanding our knowledge of the components of high school students’ conceptual ecologies through its definition of the categories and themes associated with those components. In examining across the range of components, the study illustrates the variety and sources of science conceptions within high school students’ conceptual ecologies.  相似文献   

Cultivating divergent thinking in mathematics through an open-ended approach     

Oh Nam Kwon  Jee Hyun Park  Jung Sook Park 《Asia Pacific Education Review》2006,7(1):51-61

The purpose of this study was to develop a program to help cultivate divergent thinking in mathematics based on open-ended problems and to investigate its effect. The participants were 398 seventh grade students attending middle schools in Seoul. A method of pre- and post-testing was used to measure mainly divergent thinking skills through open-ended problems. The results indicated that the treatment group students performed better than the comparison students overall on each component of divergent thinking skills, which includes fluency, flexibility, and originality. The developed program can be a useful resource for teachers to use in enhancing their students’ creative thinking skills. An open-ended approach in teaching mathematics suggested in this paper may provide a possible arena for exploring the prospects and possibilities of improving mathematical creativity.  相似文献   

Factors Affecting Student Choice of Career in Science and Engineering: parallel studies in Australia,Canada, China,England, Japan and Portugal   总被引：1，自引：1，他引：0  

Brian E. Woolnough  Yuying Guo  Maria Salete Leite  Maria Jose de Almeida  Tae Ryu  Zhen Wang 《Research in Science & Technological Education》2013,31(1):105-121

This paper describes parallel studies carried out in six countries which investigated the factors which influence school students towards careers and higher educational studies in the physical sciences or technology. The studies consisted of a common questionnaire survey, supplemented by student interviews. It reveals differences between scientists and non scientists in regard to their preferred learning styles, to the broad factors which were influential in their career choice and to their self perception against different personality types. Many factors are common across a wide range of countries. Implications of these findings for schools, higher education and government are discussed.  相似文献   

Does exercise have a protective effect on cognitive function under hypoxia? A systematic review with meta-analysis     

Myungjin Jung  Liye Zou  Jane Jie Yu  Seungho Ryu  Zhaowei Kong  Lin Yang  Minsoo Kang  Jingyuan Lin  Hong Li  Lee Smith  Paul D. Loprinzi 《运动与健康科学(英文)》2020,9(6):562-577

ObjectiveThis study aimed to examine (1) the independent effects of hypoxia on cognitive function and (2) the effects of exercise on cognition while under hypoxia.MethodsDesign: Systematic review with meta-analysis. Data sources: PubMed, Scopus, Web of Science, PsychInfo, and SPORTDiscus were searched. Eligibility criteria for selecting studies: randomized controlled trials and nonrandomized controlled studies that investigated the effects of chronic or acute exercise on cognition under hypoxia were considered (Aim 2), as were studies investigating the effects of hypoxia on cognition (Aim 1).ResultsIn total, 18 studies met our inclusionary criteria for the systematic review, and 12 studies were meta-analyzed. Exposure to hypoxia impaired attentional ability (standardized mean difference (SMD) = –0.4), executive function (SMD = –0.18), and memory function (SMD = –0.26), but not information processing (SMD = 0.27). Aggregated results indicated that performing exercise under a hypoxia setting had a significant effect on cognitive improvement (SMD = 0.3, 95% confidence interval: 0.14 – 0.45, I² = 54%, p < 0.001). Various characteristics (e.g., age, cognitive task type, exercise type, exercise intensity, training type, and hypoxia level) moderated the effects of hypoxia and exercise on cognitive function.ConclusionExercise during exposure to hypoxia improves cognitive function. This association appears to be moderated by individual and exercise/hypoxia-related characteristics.  相似文献   

The Effects of Work Intensity on Adolescent Mental Health, Achievement, and Behavioral Adjustment: New Evidence from a Prospective Study   总被引：3，自引：0，他引：3  

Jeylan T. Mortimer  Michael D. Finch  Seongryeol Ryu  Michael J. Shanahan  Kathleen T. Call 《Child development》1996,67(3):1243-1261

This article examines the effects of work intensity on adolescent mental health, academic achievement, and behavioral adjustment. Questionnaire data were collected yearly from an initial panel of 1,000 randomly selected ninth graders (14-15 years old). Consistent with other studies, students who worked at higher intensity engaged in more alcohol use. The methodological strengths of this research (a representative panel studied prospectively over a 4-year period with minimal attrition and an analysis incorporating key control and lagged variables) provide strong evidence that adolescent work fosters alcohol use. The contention that work of high intensity has deleterious effects on mental health, academic achievement, and 2 other indicators of behavioral adjustment did not withstand our stringent tests. However, high school seniors who worked at moderate intensity (1-20 hours per week) had higher grades than both nonworkers and students who worked more hours per week.  相似文献   

The Influence of James C. McCroskey’s Research in South Korea   总被引：1，自引：1，他引：0  

Hee Sun Park  Yoo Jung Oh  Ji Youn Ryu 《Communication Research Reports》2018,35(2):190-194

In honor and remembrance of Dr. James C. McCroskey, this article looks at McCroskey’s influence in Korean academic fields. We find that McCroskey’s scholarly articles and books were increasingly cited from 2001 to 2016 and that his work has been cited in Korean journals across diverse fields. In addition to the communication and education fields, McCroskey was cited also in the fields of science and medicine in South Korea. The findings document the international and interdisciplinary impact of McCroskey’s scholarship.  相似文献