• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.679-682
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• 2008

The particle which has two different characteristics on both sides is called Janus particle which is emerging as a key material in microscale transport systems. For example, if one hemisphere has polarity and the other does not, then nonpolar sides would attract each other so that a complex cluster is formed. Thus, this fascinating material can be used as an element of twisting ball panel display, complex micro-scale clusters, drug delivery unit, and active detecting beads. The keywords in developing Janus particle are size and uniformity. Former researches solved uniformity but downsizing still remains a problem. There are three methods to generate small size particles in microchannels: co-flowing, cross-flowing, and elongational flows. In this research, we generate Janus particles smaller than 10-${\mu}$m in diameter using elongational flow in microchannels. And we use UV initiator with Hydrogen UV source to solidify micro size particles. One hemisphere of the particle is coated with rhodamin for visualization.

• 한국의류학회지
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• 제44권1호
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• pp.53-67
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• 2020

The purpose of this study is to analyze the foot shape and size specification of male high school students. 3D modeling programs such as 'Artec Studio', 'CATIA', and 'Auto CAD' measured the 3D scan data of 361 male high school students provided by KATS. Through principal factor analysis, 10 factors were extracted, including foot length, medial-lateral ratio, and foot length ratio. As the result of the cluster and ANOVA with post-hoc test (Duncan method), the differences among types were clarified. Type 1 (24.7%) represented outward medial-lateral ratio (M-L ratio) with the lowest instep, ankle and little deformed first toe. Type 2 (41.8%) was characterized by the shortest, even M-L ratio, thin ankle and heel, the highest instep and ankle. Type 3 (33.5%) showed the longest, inward M-L ratio, thick ankle and heel, and deformed first toe. As the cross-tabulation of foot length and ball circumference, 17.2 percent was not covered by KS standard; in addition, the foot length was longer than the KS standard. The correlation analysis of key dimensions showed that foot length and ball circumference were highly correlated with other items; therefore, regression equations were derived to estimate other foot measurements using these two items as independent variables.

• The Journal of Korean Physical Therapy
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• 제27권4호
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• pp.196-200
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• 2015

Purpose: The purpose of this study was to examine the muscle activity of the trunk muscles during balance exercises on a stable and unstable surface in patients with stroke. Methods: Thirteen subjects (8 males, 5 females) with stroke were enrolled in the study. Muscle activity was recorded using surface EMG electrodes from the affected side of the erector spinae, external oblique, and internal oblique muscles. The exercise was performed under three conditions. For the first condition for balance exercise, subjects were instructed to sit on an exercise mat with legs extended. The second condition was to sit with legs extended, with a balance pad under their buttocks. The third condition was to sit with legs extended, have a balance pad under the buttocks and a balance cushion under the lower legs. Results: This study showed significant differences in EMG activities during both arm lifting exercise and weight shifting exercise between conditions. This study showed that the EMG activities of the erector spinae, external oblique, and internal oblique muscles were significantly higher when the trunk exercise was performed using the balance pad with balance ball than when using the stable surface. Conclusion: In conclusion, performing balance exercises using an unstable surface is a useful method for facilitating trunk-muscle strength and hence trunk stability.

• 한국정밀공학회지
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• 제16권5호통권98호
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• pp.48-57
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• 1999

Applications of thresholding technique are based on the assumption that object and background pixels in a digital image can be distinguished by their gray level values. For the segmentation of more complex images, it is necessary to resort to multiple threshold selection techniques. This paper describes a new method for multiple threshold selection of gray level images which are not clearly distinguishable from the background. The proposed method consists of three main stages. In the first stage, a probability distribution function for a gray level histogram of an image is derived. Cluster points are defined according to the probability distribution function. In the second stage, fuzzy partition matrix of the probability distribution function is generated through the fuzzy clustering process. Finally, elements of the fuzzy partition matrix are classified as clusters according to gray level values by using max-membership method. Boundary values of classified clusters are selected as multiple threshold. In order to verify the performance of the developed algorithm, automatic inspection process of ball grid array is presented.

• 공학교육연구
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• 제25권2호
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• pp.42-56
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• 2022

This study aimed to investigate the views of STEM college students on the social responsibility of scientists and engineers. A total of 660 students in STEM majors at several Korean universities participated in the study. We assessed social responsibility among college students in STEM majors using the VSRoSE scale, which taps into eight different domains of social responsibility: Concern for human welfare and safety (HUMAN), Concern for environmental sustainability (ENVIR), Consideration of societal risks and consequences (CONSEQ), Consideration of societal risks and consequences (CONSEQ), Consideration of societal needs and demands (NEEDS), Pursuit of the common good (COMGOOD), Civic engagement and services (CIVIC), Communication with the public (COMMU), and Participation in policy decision-making (POLICY). Group differences in social responsibility by gender, majors, and years in school were examined. Mean scores in HUMAN, ENVIR, and CONSEQ were relatively higher than those in NEEDS, COMGOOD, CIVIC, COMMU, and POLICY. Cluster analysis identified five different groups with similar patterns of social responsibility scores. In addition to two groups with overall high and low scores across all eight factors of VSRoSE, three additional groups with different combinations of high and low scores in different factors were identified. The results indicated that students with low social responsibility are not homogeneous and these heterogeneous sub-groups of students will need tailored interventions highlighting different factors of social responsibility that they lack. Pedagogical implications of social responsibility for education were discussed.