• Journal of The Korean Association For Science Education
• /
• v.35 no.4
• /
• pp.773-790
• /
• 2015

Conducted as an ethnographic examination of science teaching and learning in an Innovative Middle School in Korea, this study employs sociocultural theory to examine how structures afford and limit student participation in an innovative school designed to promote student-centered learning. Data includes teacher and student interviews, student responses to a questionnaire, classroom observations, and analysis of video recordings of ten lessons in two in two 8th grade science classes. Using structure|agency dialectic theory, we identify and describe some structures that afford and limit teacher and student agency at the micro (science classrooms), meso (school), and macro (Korean society) levels to raise some questions about current reform measures, such as innovation schools, that seek to position classroom teachers as agents for change in science education reform in Korea. Findings suggest that while teachers and school administrators play an essential role in structuring learning opportunities at the meso and micro levels, they have limited agency to address structural constraints originating at the macro-level, which can negatively impact teaching and learning in the science classroom. We offer implications for policy and practice and argue the need for more qualitative research, informed by sociocultural theory, to inform science education reform efforts in Korea.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2016.11a
• /
• pp.118.1-118.1
• /
• 2016

The laser surface modification has been reported for its functional applications for improving tribological performance, wear resistance, hardness, and corrosion property. In most of these applications, continuous wave lasers and pulsed lasers were used for surface melting, cladding, alloying. Since flexibility in processing, refinement of microstructure and controlling the surface properties, technology utilizing lasers has been used in a number of fields. Especially, femtosecond laser has great benefits compared with other lasers because its pulsed width is much shorter than characteristic time of thermal diffusion, which leads to diminish heat affected zone. Moreover, laser surface engineering has been highlighted as an effective tool for micro/nano structuring of materials in the bio application field. In this study, we applied femtosecond and nanosecond pulsed laser to treat biometals, such as Mg, Mg alloy, and NiTi alloy, by heating to improve corrosion properties and functionalize their surface controlling cell response as implantable biomedical devices.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.1036-1042
• /
• 2003

The hot embossing process has been mentioned as one of major nanoreplication techniques. This is due to its simple process, low cost, high replication fidelity and relatively high throughput. As the initial step of quantitating the embossing process , simple parametric study about embossing time have been carried out using high-resolution masters which patterned by the DRIE process and laser machining. Under the various embossing time, the viscous flow of thin PMMA films into microcavities during compression force has been investigated. Also, a study about simulating the viscous flow during embossing process has planned and continuum scale FDM analysis was applied on this simulation. With currently available test data and condition, simple FDM analysis using FLOW3D was made attempt to match simulation and experiment.

• Journal of Powder Materials
• /
• v.23 no.2
• /
• pp.170-176
• /
• 2016

Lithium-ion batteries (LIBs) are rapidly improving in capacity and life cycle characteristics to meet the requirements of a wide range of applications, such as portable electronics, electric vehicles, and micro- or nanoelectro-mechanical systems. Recently, atomic layer deposition (ALD), one of the vapor deposition methods, has been explored to expand the capability of LIBs by producing near-atomically flat and uniform coatings on the shell of nanostructured electrodes and membranes for conventional LIBs. In this paper, we introduce various ALD coatings on the anode, cathode, and separator materials to protect them and improve their electrochemical and thermomechanical stability. In addition, we discuss the effects of ALD coatings on the three-dimensional structuring and conduction layer through activation of electrochemical reactions and facilitation of fluent charge collection.

• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.12
• /
• pp.1101-1106
• /
• 2014

Hybrid manufacturing technology has been advanced to overcome limitations due to traditional fabrication methods. To fabricate a micro/nano-scale structure, various manufacturing technologies such as lithography and etching were attempted. Since these manufacturing processes are limited by their materials, temperature and features, it is necessary to develop a new three-dimensional (3D) printing method. A novel nano-scale 3D printing system was developed consisting of the Nano-Particle Deposition System (NPDS) and the Focused Ion Beam (FIB) to overcome these limitations. By repeating deposition and machining processes, it was possible to fabricate micro/nano-scale 3D structures with various metals and ceramics. Since each process works in different chambers, a transfer process is required. In this research, nanoscale 3D printing system was briefly explained and an alignment algorithm for nano-scale 3D printing system was developed. Implementing the algorithm leads to an accepted error margin of 0.5% by compensating error in rotational, horizontal, and vertical axes.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.9 no.2
• /
• pp.223-228
• /
• 2016

A digital micromirror system was proposed for future smart learning. This system is the compact micro-projector with a built-in CMOS sensor modules. It can provide the various interfaces. The basis of interface is to recognize the finger tip on projected image. But the recognition rate of finger tip is very low due to various image degradations. In this paper, we propose the finger tip recognition algorithm that minimize the image degradation factors by using the Retinex transform and IR structuring light. By verifying the availability of the algorithm through experiment, the performance of finger tip recognition was confirmed. Therefore, the user interface can be able to be enhanced significantly in DMS.

• Nuclear Engineering and Technology
• /
• v.56 no.6
• /
• pp.2367-2374
• /
• 2024

In this paper, based on the need for high-strength connections between all-tungsten-oriented plasma materials and thermal sinking materials of copper and its alloys in nuclear fusion devices, a study on the effect of tungsten surface laser micro structuring on the interfacial bonding properties of W/Cu joints was carried out. In the experiment, the connectors were prepared by vacuum fusion infiltration technology, and the effects of microgroove structure on the mechanical and thermal conductivity of W/Cu connectors were investigated under different parameters (including microgroove pitch, microgroove depth, and microgroove taper). The maximum shear strength is 126.0 MPa when the pitch is 0.15 mm and the depth is 34 ㎛. In addition, the negative taper structure, i.e., the width of the entrance of the microstructure is smaller than the width of the interior of the microstructure, is also investigated. The shear tests show that there is an approximately linear relationship between the shear strength of W/Cu and taper. Compared with the positive taper, the shear strength of the samples with the same morphological density and depth of the tungsten surface is significantly higher.

• Journal of Species Research
• /
• v.1 no.1
• /
• pp.4-34
• /
• 2012

Parastenocaris koreana sp. nov. is described based on examination of numerous adult specimens of both sexes from several localities in Korea. Scanning electron micrographs are used to examine intra- and interpopulation variability of micro-characters, in addition to light microscopy. The new species is most closely related to the Japanese P. biwae Miura, 1969, which we redescribe based on newly collected material from the Lake Biwa drainage area. The two species differ in size, relative length of the caudal rami, shape of the anal operculum, shape of the genital double somite, relative length of the inner distal process on the female fifth leg, as well as relative length of the apical setae on the second, third, and fourth legs exopods in both sexes. Detailed examinations of three disjunct populations of P. koreana reveal also some geographical variation, especially in the surface ornamentation of somites, which may indicate some population structuring or even cryptic speciation. Lack of intraspecific variability in the number and position of sensilla on somites, as well as their potential phylogenetic significance, is a novel discovery. Both species examined here belong to the brevipes group, which we redefine to include 20 species from India (including Sri Lanka), Australia, East Asia, Northern Europe, and North America. A key to species of this group is also provided. In order to test the monophyly of the redefined brevipes group with highly disjunct distribution, as well as relationship between different species, a cladistics analysis is performed based on 39 morphological characters and with help of three outgroup taxa. Six equally parsimonious cladograms are generated, all of which show that the ingroup is well defined by at least three synapomorphies. Reconstructed phylogeny questions the previously suggested hypothesis about the origin of this group in South East Asia, with one Australian species showing the most basal position. We speculate that the present distribution of this group may be a combination of ancient vicariance and subsequent dispersal, with a possible origin in the Gondwanaland, in the rift valley between Australia and India.

• International Journal of Human Ecology
• /
• v.12 no.2
• /
• pp.95-107
• /
• 2011

Recent intervention studies document that mother-child dyads with higher levels of Emotional Availability (EA) report fewer child behavior problems than dyads with lower EA. This study examines possible mechanisms that lead to this result by looking at the parent-child micro-system as a whole, with multi-dimensional relationships that include individual differences in the child's cognitive level, parental stress and parent-child interaction. A total 67 children ($1{\frac{1}{2}}$ to $5\;{\frac{1}{2}}$ years of age) and their mothers were videotaped during 30-min play interactions. Interactions were coded using the Emotional Availability (EA) Scales (Biringen, Robinson, & Emde, 1998). Mothers completed Parenting Stress Index-Short Form, Child Behavior Checklist/$1\;{\frac{1}{2}}$ - 5, and the Ages Stages Questionnaire. The findings showed that mothers with higher levels of parenting stress were more likely to be intrusive, hostile, insensitive, and had a tendency to do less structuring in play. The children of stressed and depressed mothers demonstrated less involvement and responsiveness towards their mothers. Children who have higher dyadic EA scores experienced fewer externalizing and internalizing problems. SEM analyses results showed a mediation effect of EA on the association between maternal psychological well-being and child behavior problems. Fewer deficits in child communication skills and problem solving skills that were related with lower parenting stress and depression were associated with higher maternal non-intrusiveness. Higher non-intrusiveness was related to less internalizing and externalizing problems that indicated the indirect effect of child cognitive competence. Possible interpretations and implications of the study findings are discussed.

• Journal of the Korean Institute of Navigation
• /
• v.4 no.2
• /
• pp.7-38
• /
• 1980

Nowadays researchers attach a great importance to the problems concerned with scientific information in the field of science and engineering. There are some reasons for it, that is, ⅰ) the amount of scientific information increases in proportion to the activities of scientists and engineers, so it is difficult to pick up a real valuable information ⅱ) it becomes more important to use a variety of information in proportion to the spread ofthe branch of science ⅲ) since the medium of scientific information is mostly technical papers, it is very difficult to mechanically transact these papers and to keep all documents and scientific informations for a long time. To cope with these difficult situations, many technical skills have been developed, for example, data-base, automatic information retrieval, micro-film and so on. But there are comparatively few investigation on the matter how the researchers who are users and producers think about the systematization of scientific information usage, so this paper investigates the thought and information needs of researchers, and proposes a basis of a method for systematization of scientific information usage. The author inspects the actual conditions of scientific information, reconsider the method which has been used and investigates the matter of how researchers whose interest is closely related to the study of marine affairs think about problems of scientific information usage by thequestionarie of Fuzzy-DEMATEL method. Also, FSM which is method for structuring hierarchy for the several complex problems on the basis of fuzzy sets theory is adopted as a tool of analysis. We can understand the key problems and make a story to solve the systematization of scientific information usage from the results of the analysis and those results will be directly applicable to construct a new system for scientific information usage.