• Journal of The Korean Association For Science Education
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• v.21 no.5
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• pp.893-905
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• 2001

Korean students ranked the 3rd out of 32 participating countries in the first cycle of PISA(Programme for International Student Assessment) science field, which assessed 15-years-old students' scientific literacy. PISA developed several variables such as parents' socio-economic status, parents' educational attainment, family wealth, and cultural possession, to investigate the effects of background variables on scientific literacy. On the other hand, motivation and engagement in science study were not given much attention, partly because science was the minor area in the first cycle of PISA. Therefore, PISA Korea developed a series of variables to collect data on students' learning motives and out-of-school activities in science as a national option. The results are as followings. First, Korea was found to be one of the PISA participating countries with the scientific literacy achievement least influenced by parents' socio-economic status, family wealth, and parents' cultural possession. Second, the degree of achievement in scientific literacy according to parents' educational attainment was in a positive correlation, similar to the overall tendency of PISA. Third, the most crucial learning motive for Korean students was their desire to develop scientific thinking abilities or obtain science knowledge. On the other hand, choosing jobs in the field of science or parental expectation was the least important learning motive. In particular, the motive for scientific learning was found to have a positive relationship with the degree of scientific literacy achievement. Therefore, the higher the students achievement, the stronger the motive for scientific learning in order to develop their ability to think scientifically or acquire science knowledge. Fourth, Korean students were shown to participate very little in out-of-school scientific activities other than watching TV programs related to science. Whatever the activities may be, the more actively involved students are in out-of-school scientific activities, the higher their scientific literacy achievement. Fifth, Korean girls were rather passive compared to boys in all areas, including science learning motive and out-of-school scientific activities. The gender difference was especially more pronounced in out-of-school scientific activities with wider gaps in such activities as reading scientific books or articles and visiting science-related web sites.

• Journal of Korean Society of Rural Planning
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• v.21 no.4
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• pp.13-26
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• 2015

This study was conducted to analyze the policy impacts of the '2014 Rural Field Forum'. From 2013, Ministry of Agriculture, Food and Rural Affairs implemented Rural Field Forum to push forward rural development of inhabitants' initiative. In this study, we have evaluated that Rural Field Forum has crucial impacts on residents' competence, region capability and driving force of project by targeting the 374 residents of 350 villages in 9 states who participated in 2014 Rural Field Forum. We also sought for the solution to institutional improvement. Futhermore we analyzed each of leader group and normal residents for departmentalization of policy effects. Taken together, the analysis reveals that: 1)Rural field forum is demonstrated to have a positive effect on the establishment and execution of village development plan and all of its necessary components. 2)Regarding the effect on the village capabilities, the understanding and recognition of village organization was shown to be improved. 3)About regional capabilities, the interest in village project was advanced. 4)In terms of the project execution, Rural field forum turned out to affect the village council processes positively. 5)lastly, between the leader and the residents, the difference effectiveness between them revealed, with the same directivity and considerably bigger effect felt by the leader than by the residents overall.

• Journal of radiological science and technology
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• v.33 no.3
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• pp.253-260
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• 2010

The primary focus of this study was to explore the variation in dose distributions of electron beams between different types of construction structure of cut-out blocks embodied in electron cones, given that the structure is considered one of the causes of multiple scattered radiation from electrons which may affect dose distributions. For evaluation, two types of cut-out blocks, divergency and straight, manufactured for this study, were compared in terms of area of interval in distribution of dose, and flatness and symmetric state of surface being radiated. The results showed that divergency cut-out blocks reduced the lateral scattering effects on the thickness of cut-out blocks more substantially than straight ones, leading to more uniform dose distribution at baseline depth. Notably in divergency cut-out blocks, the high dose area decreased more significantly, and more uniform dose distribution was observed at the edge of the irradiated field. This points to a need to consider the characteristics of dose distribution of electron beams when setting up radiotherapy planing at the venues. Therefore, this study is significant as an exploratory work for ensuring high accuracy in dose delivery for patients.

• Journal of Biosystems Engineering
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• v.29 no.2
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• pp.109-120
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• 2004

To obtain basic information for precision agriculture, spatial variability of rice growth condition was evaluated in 100m ${\times}$100m paddy field. The rice growth condition of four hundred locations in the field were investigated to analyze the spatial variability of their properties ; SPAD, plant length and tiller number. Geostatistical analysis was carried out to examine within-field spatial variability using semivariograms and kriged maps as well as descriptive statistics. Descriptive statistics showed that the coefficient of variation for SPAD, plant length, and tiller number exceeded 5.70 %, suggesting a relatively high variability. Geostatistical analysis indicated a high spatial dependence for all the properties except for the second tiller number. The range of spatial dependence was about 20 m for SPAD, plant length, and tiller number. Based on the results of spatial dependence, kriged maps were prepared for the properties to analyse their spatial distribution in the field. The results reflected the history of field management. In conclusion, the need for site-specific field management and possibility of precision agriculture were demonstrated even in an almost flat paddy field.

• Journal of Magnetics
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• v.18 no.1
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• pp.14-20
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• 2013

For the treatment of osteoarthritis, pulsed electromagnetic field stimulus has been suggested as a useful therapeutic method in rehabilitative medicine. Most studies have been performed under low-frequency and low-energy to find out biological properties for stimulating chondrocyte with pulsed magnetic field. In this study, the effect of strong pulse magnetic field on the human chondrosarcoma cells (SW-1353) has been investigated by means of cell counting, morphologies, and gene expression of cartilage extracellular matrix genes. The SW-1353 cells were exposed under the field intensities of 270, 100, 55, 36, and 26 mTesla during 6 hours a day in 5 consecutive days. The pulse magnetic field with an LRC oscillating signal has the pulse width of 0.126 msec and stimulation period of 1 sec. For the 270 and 100 mTesla stimulation, the cell proliferation significantly increased in 21-24% as compared with the non-stimulated cells. Gene expression of cartilage extracellular matrix genes (ACAN, COMP and COL2A1) was assayed by quantitative real time-PCR method. The ACAN gene expression showed a significant brightness, which means the increase on gene expression, compared with the non-stimulated cells. Our results suggest that the strong pulse magnetic field stimulation can be utilized to accelerate cell proliferation and gene expression on human chondrosarcoma cells.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.4
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• pp.570-577
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• 2002

Charged liquid particle's behavior in electric and flow field was simulated to define the effect of electric field on the contact area and its dispersion. For the simulation of flow and electric field finite volume method was applied. To find out the particle's moving path in that field lagrangian equation of motion was solved by Runge-Kutta methods. We assumed that the particle was charged 10% of Rayleigh limit while the particle passing through the electrode and the particle does not have an effect on the electric field. In case of 30[Kv] of voltage charging the particles injected from the central 60% of the nozzle injection area adhere to the grounded moving plate and no dispersion occurred. Increasing the charged voltage to 40[Kv], it brought about the same phenomena as that of 30[Kv] charging except the dispersion. Voltage increasing from 30[Kv] to 40 [Kv] caused higher Coulomb force acts on the particle and it made the particle dispersion.

• Journal of Digital Convergence
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• v.8 no.3
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• pp.79-93
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• 2010

This study aims to verify whether field-dependence and field-independence cognitive style have regulatory effect or not on information quality and system quality of digital textbooks in learning satisfaction. In order to accomplish the purpose, the research was carried out with 325 students of digital textbook research school who are fifth and sixth grade at a primary school living in Seoul metropolitan city. Results from the verification of hypotheses are as follows: when learning satisfaction of digital textbooks is affected by information quality and system quality influence satisfaction, it is given a positive moderating effect by the variables of field-dependence and field-independence cognitive style.

• Progress in Superconductivity and Cryogenics
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• v.4 no.1
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• pp.55-60
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• 2002

$100 A/mm^2$ class Bi-2223 tapes have recently become commercially available. Some important characteristics of the tapes, e .g. critical current, ac loss, characteristics at joint, fault current characteristics, are required for an application such as a power cable or a power transformer. In this paper they have been investigated experimentally. The results indicate that the self-field loss of the high current density tapes is not negligible, compared to resistive loss in a copper wire for the same currents. In a cable, the self-field loss for relatively large currents is much larger than the magnetization loss due to an external field. But in a transformer, the magnetization loss is dominant, compared to the self-field loss. Finally the fault current characteristics show that the high current density tapes are never safe from burn-out even for fault currents with a few cycles.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.70-75
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• 2014

Super-resolution near-field structure (super-RENS) read-out samples are affected by a nonlinear and noncausal channel, which results in inter-symbol interference (ISI). In this study, we investigate asymmetry or domain bloom in super-RENS in terms of equalization. Domain bloom is caused by writing process in optical recording. We assume in this work that the asymmetry symbol conversion scheme is to generate asymmetric symbols, and then a linear finite impulse response filter can model the read-out channel. For equalizing this overall nonlinear channel, the read-out signals are deconvolved with the finite impulse response filter and its output is decided based on the decision rule table that is developed from the asymmetry symbol conversion scheme. The proposed equalizer is investigated with the simulations and the real super-RENS samples in terms of raw bit error rate.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1673-1678
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• 2015

This paper describes magnetic field on power cable in underground transmission systems. Based on specification which is being used in domestic power utility, magnetic field was analyzed in accordance with line arrangement, line burial depth and phase spacing. Magnetic field magnitude and its trend were understood in each circuit type such as double circuits, triple circuits and quadruple circuits of underground transmission systems. In addition, magnetic field was analyzed according to phase arrangement changing in each circuit. Finally, the proper phase arrangement configuration type was suggested by the evaluation of analysis result. Magnetic field was calculated by using Biot-Savart's law. According to the evaluated magnetic fields based on phase layout configuration in each circuit, it figured out that each of magnetic fields was different. As a result, this paper proposes a proper phase layout configuration for generating minimum magnetic field. It is evaluated that the phase layout configuration in each circuit proposed in this paper can be used at actual underground transmission systems.