• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.39 no.5
• /
• pp.425-433
• /
• 2015

In this paper, we have numerically investigated two-dimensional dielectrophoretic (DEP) motions of a single particle suspended freely in a viscous fluid, interacting with a nearby nonconducting planar wall, under an externally applied uniform direct-current electric field. Particularly, we solve the Maxwell equation with a large sharp jump in the electric conductivity at the particle-fluid interface and then integrate the Maxwell stress tensor to compute the DEP force on the particle. Results show that, under an electric field parallel to the wall, one particle is always repelled to move far away from the wall and the motion depends strongly on the particle-wall spacing and the particle conductivity. The motion strength vanishes when the particle is as conductive as the fluid and increases as the conductivity deviates further from that of the fluid.

• Journal of the Korean School Mathematics Society
• /
• v.17 no.2
• /
• pp.235-249
• /
• 2014

In this paper, teaching contents in area between Korea and Japan's first grade math textbooks are compared. Based on the results of this comparison, implications for improving our grade 1 math textbooks are obtained as follows. Firstly, when describing the configuration of two-digit numbers, it needs to be considered that, after the mathematical description of a concrete material representing two-digit numbers, then it should be processed mathematically. Secondly, with respect to the composition and decomposition of numbers, use of the expression of 'some number and some number' needs to be considered. Thirdly, when reading addition expression and subtraction expression with an equal sign, the way of reading them with terms 'sum' and 'difference' respectively needs to be reconsidered. Fourthly, use of the distinct expression for the supplementing situation and the merging situation respectively and use of the distinct expression for the removing situation and the comparing situation respectively need to be considered. Fifthly, the jump in representing the expression of subtraction of two numbers as the expression of the subtraction or mixed operation of three numbers to explain (some number)-(some number) with borrowing need to be resolved.

• The Journal of Fisheries Business Administration
• /
• v.36 no.3 s.69
• /
• pp.65-88
• /
• 2005

The fisheries industry has been changed drastically during the so - called Golden Growth Era of Korea. Recently, WTO/DDA agenda drove industries out of their safe refuges toward infinite competitions in the world. This paper aims at finding out distinguished features in the structural changes of fisheries since 70s. Furthermore, policy implications are investigated in order for the fisheries to survive in the outdoors. The paper consists of the following sections. First, we consider why and for what the structural change of fisheries in historical perspective should be investigated. And we introduce how we can approach to the goal in various aspects in the second section. In the third section, we examine the historical change of Korean fisheries in respect of national economy, resource allocation mechanism, industrial structure, and fisheries society. In the fourth section, we extract the development steps in fisheries from the periodic characteristics, using various methods of the above approaches. And we deduce the next step for Korean fisheries in the future. Finally, we conclude that there needs some turning point of fisheries policies in Korea, striving to foster the fisheries industry in the future. As results of empirical analysis in this paper, we find that fisheries industry in Korea has experienced some momentous changes during 30 years, using I/O data of B.O.K. The weight of fisheries sector in the whole economy of Korea increased during early 70s, initially leading the national economy to export - oriented engine for growth. But fisheries sector has shrunk rapidly since late 70s. Almost resources in Korea were allocated to expanding manufacturing industries. Further, fisheries industry has encountered perfect international competitions since the late 90s. This paper draws that fisheries industry in Korea will jump across to next step of qualitative growth in the future. Therefore, we recommend that the policies should be focused on enhancing the industrial competitiveness, switching quantitative growth to qualitative advance in fisheries.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.20 no.6
• /
• pp.779-787
• /
• 2007

This paper presents a highly efficient moving least squares finite difference method (MLS FDM) for a heat transfer problem of bi-material with interfacial boundary. The MLS FDM directly discretizes governing differential equations based on a node set without a grid structure. In the method, difference equations are constructed by the Taylor polynomial expanded by moving least squares method. The wedge function is designed on the concept of hyperplane function and is embedded in the derivative approximation formula on the moving least squares sense. Thus interfacial singular behavior like normal derivative jump is naturally modeled and the merit of MLS FDM in fast derivative computation is assured. Numerical experiments for heat transfer problem of bi-material with different heat conductivities show that the developed method achieves high efficiency as well as good accuracy in interface problems.

• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.47-51
• /
• 2015

Ground Level Enhancements (GLEs) in cosmic ray intensity observed during the period of 1997-2012 have been studied with energetic solar features and disturbances in solar wind plasma parameters and it is seen that all the GLEs have been found to be associated with coronal mass ejections, hard X-ray solar flares and solar radio bursts. All the GLEs have also been found to be associated with sudden jumps in solar proton flux of energy of ${\geq}60Mev$. A positive correlation with correlation coefficient of 0.48 has been found between the maximum percentage intensity (Imax%) of Ground Level Enhancements and the peak value of solar proton flux of energy (${\geq}60Mev$). All the Ground Level Enhancements have been found to be associated with jumps in solar wind plasma velocity (JSWV) events. A positive correlation with correlation coefficient of 0.43 has been found between the maximum percentage intensity (Imax %) of Ground Level Enhancements and the peak value of solar wind plasma velocity of associated (JSWV) events. All the Ground Level Enhancements have been found to be associated with jumps in solar wind plasma pressure (JSWP) events. A positive correlation with correlation coefficient of 0.67 has been found between the maximum percentage intensity (Imax %) of Ground Level Enhancements and the peak value of solar wind plasma pressure of associated (JSWP) events and of 0.68 between the maximum percentage intensity (Imax %) of Ground Level Enhancements and the magnitude of the jump in solar wind plasma pressure of associated (JSWP) events.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.2
• /
• pp.101.2-101.2
• /
• 2012

Shocks are ubiquitous in astrophysical plasmas: bow shocks are formed by the interaction of solar wind with planetary magnetic fields, and supernova explosions and jets produce shocks in interstellar and intergalactic spaces. The global morphologies of these shocks are usually described by a set of magnetohydrodynamic (MHD) equations which tacitly assumes local thermal equilibrium, and the resulting Rankine-Hugoniot shock jump conditions are applied to obtain the relationship between the upstream and downstream physical quantities. While thermal equilibrium can be achieved easily in collisional fluids, it is generally believed that collisions are infrequent in astrophysical settings. In fact, shock widths are much smaller than collisional mean free paths and a variety of kinetic phenomena are seen at the shock fronts according to in situ observations of planetary shocks. Hence, both the MHD and kinetic equations have been adopted in theoretical and numerical studies to describe different aspects of the physical phenomena associated with astrophysical shocks. In this paper, we present the results of 3D relativistic particle-in-cell (PIC) simulations for ion-electron plasmas, with focus on the shock structures: when a jet propagates into an unmagnetized ambient plasma, a shock forms in the nonlinear stage of the Weibel instability. As the shock shows the structures that resemble those predicted in MHD systems, we compare the results with those predicted in the MHD shocks. We also discuss the thermalization processes of the upstream flows based on the time evolutions of the phase space and the velocity distribution, as well as the wave spectra analyses.

• Physical Therapy Rehabilitation Science
• /
• v.7 no.1
• /
• pp.13-17
• /
• 2018

Objective: This was a correlation study for predicting the power to improve the distance of golf players and developing an effective power program. Design: Cross-sectional study. Methods: The subjects of this study were 24 healthy males and females in their 20s and 30s who were golf athletes living in Seoul and Gyeonggi-do. In the Titleist Performance Institute (TPI) Level 1 test, the twelve swing characteristics include components of stability, mobility, body conditioning ability, and balance. The power test consisted of a vertical jump (VJ) in order to examine the power of the lower body, the seated chest pass (SCP) was used to examine upper body power, and the sit up and throw (SUAT) was used to examine the power of the upper body and core for the TPI Level 2 test. Results: The results of this study showed that the 90/90 was correlated with VJ, SUAT, and SCP scores (p<0.05). Single leg stance was correlated with VJ, SUAT, over head deep squat, and bridge with leg extension were correlated with VJ (p<0.05). The toe touch was correlated with SUAT results (p<0.05). Conclusions: The results of this study showed that the TPI Level 1 test and power test were correlated with the performance of the golf players. Future studies have shown that fitness program development and further research are needed.

• Journal of Preventive Medicine and Public Health
• /
• v.27 no.3 s.47
• /
• pp.531-545
• /
• 1994

In a TV component manufacturing factory, 102 male workers aged $20{\sim}39$ years old were participated in testing for physical fitness. At the same time, worker's periodic health examination was done. Test battery for physical fitness include grip strength, trunk flexion, standing long jump, side step, single leg balance with eye close, push ups and Harvard step test. As a result of testing for physical fitness, synthetically, there is no difference between manufacturing workers and officers. By bioelectrical impedance test, it means a declining tendency to all 7 factors in the obese workers, and so, it is important for obese workers not only to promote physical fitness but also to promote health. Excluding grip strength and single leg balance with eye close, 5 fitness factors are negatively associated with degree of diastolic Blood pressure, but it is statistically not significant. And levels of sGOT & sGPT have no association with physical fitness factors.

• Journal of Families and Better Life
• /
• v.34 no.5
• /
• pp.83-98
• /
• 2016

The purpose of this study was to investigate the relationship among toddler's symbolic play level, mother's responsiveness and verbal interaction. The subjects were 56 pairs of 24-29 months old toddlers and their mothers. The toddler's symbolic play level was classified using categories by Gowen(1995). The mother's verbal interaction was coded during a 10-minute-free play session with her toddler using Caldera, Huston, and O'Brien's(1989) categories. PICCOLO(The Parenting Interactions with Child Checklist of Observations Linked to Outcomes) by Roggman, Cook, Innocenti, Jump, Norman, & Christiansen(2009) was used to investigate the mother's responsiveness. While the mothers played with their toddlers during a 10-minute-free play session, their interaction were videotaped. The data were analyzed by means, t-test, and correlations. The results of the study were as follows: First, the mean levels of the toddler's symbolic play were in level 3, 'the pretending others'. Also girls spent more symbolic play time with mothers than boys. Second, mothers' responsiveness was generally high in free play with their toddlers. Mothers frequently used 'questions' 'comments' and 'fantasy statements'. Mothers with girls used more 'questions' than mothers with boys. Third, there was a significant relationship among toddler's symbolic play level, mother's responsiveness and verbal interaction. Maternal responsiveness and 'fantasy statements' were positively related with the mean level, and the frequency of play. The 'questions' and 'answers' were also related with symbolic play level and frequency. But 'praise' was negatively related with symbolic play frequency. In conclusion, this study suggested that toddler's symbolic play level was related with mother's responsiveness and verbal interaction during free play.

• Journal of the Korea Computer Graphics Society
• /
• v.21 no.1
• /
• pp.23-31
• /
• 2015

We present a method for creating realistic 2D stick figure animations easily and rapidly using captured motion data. Stick figure animations are typically created by drawing a single pose for each frame manually for the entire time interval. In contrast, our method allows the user to summarize an action (e.g. kick, jump) for an extended period of time into a single image in which one or more action lines are drawn over a stick figure to represent the moving directions of body parts. In order to synthesize a series of time-varying poses automatically from the given image, our system first builds a deformable character model that can make arbitrary deformations of the user's stick figure drawing in 2D plane. Then, the system searches for an optimal motion segment that best fits the given pose and action lines from pre-recorded motion database. Deforming the character model to imitate the retrieved motion segment produces the final stick figure animation. We demonstrate the usefulness of our method in creating interesting stick figure animations with little effort through experiments using a variety of stick figure styles and captured motion data.