• The Journal of Korean Institute for Practical Engineering Education
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• v.4 no.2
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• pp.75-83
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• 2012

Due to the proliferation of smart devices, worldwide market growth of e-book content steep, but the domestic market shows relatively low growth rate and small size. In this study, a distribution modeling of the e-book business as a way to solve the problem of the domestic market of disabled was carried out to analyze the Amazon.com and Apple's e-book content distribution structure of the active leader in the U.S. market. And we tried to suggest a solution by investigation and analysis of the college students's receptive attitude on the e-book content as the main target to enable the markets based on the interest for publication. In adoption attitude survey, mainly low-readability and lack of content problem were reasons not to accommodate. There is a need to improve the quantity and quality of content through with technological advances and market participation together. For more participation, we expect to take advantage of the results of this study to establish or improve the systematic distribution structure.

• Korea journal of population studies
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• v.34 no.1
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• pp.99-127
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• 2011

This study examines whether educational differentials in health are greater in more recent cohorts in Korea. This study utilizes latent growth-curve modeling to examine intercohort trends in health for three educational subgroups, using panel data (2003-2007) based on a national probability sample of 9,639 adults. Among young and middle adults with less than a high school diploma, the 4-year newer cohort demonstrated better health at the same age, implying a favorable trend. Middle and older adults with college level and a high school diploma also enjoyed favorable trends in health. This study suggests the possibility that the education-based overall disparity in health is increasing, but there are variations in the trend depending on age group. The increasing disparity mainly occurred among older adults.

• Composites Research
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• v.18 no.3
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• pp.21-30
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• 2005

Vacuum hot pressing has been used for the development of titanium metal matrix composites using foil-fiber-foil method. Heterogeneous microstructures prior to and following consolidation have been quantified, and the relations to densification behavior investigated. As shown by the results, dramatic variations of the microstructures including equiaxed $\alpha$, transformed $\beta$ and $ Widmanst\ddot{a}tten$ $\alpha$ are obtained during the process according to the fiber distributions. The dependence of microstructures on the consolidation then has been explained in terms of the change in mechanisms such as grain growth and recrystallization that occur with changing levels of inhomogeneity of deformation. Further, micro-mechanics based constitutive model enabling the evolution of density over time together with the evolutions of microstructure to be predicted has been developed. The mode developed is then implemented into finite element scheme so that practical process simulation has been carried out.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06b
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• pp.285-309
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• 1996

Non oxide ceramics such as nitrides of transition metals have shown significant potential for future economic impact, in diverse applications in ceramic, aerospace and electronic industries, as refractory products, abrasives and cutting tools, aircraft components, and semi-conductor substrates amid others. Combustion synthesis has become an attractive alternative to the conventional furnace technology to produce these materials cheaply, faster and at a higher level of purity. However he process os highly exothermic and manifests complex dynamics due to its strongly non-linear nature. In order to develop an understanding of this process and to study the effect of operational parameters on the final outcome, numerical modeling is necessary, which would generated essential knowledge to help scale-up the process. the model is based on a system of parabolic-hyperbolic partial differential equations representing the heat, mass and momentum conservation relations. The model also takes into account structural change due to sintering and volumetric expansion, and their effect on the transport properties of the system. The solutions of these equations exhibit steep moving spatial gradients in the form of reaction fronts, propagating in space with variable velocity, which gives rise to varying time scales. To cope with the possibility of extremely abrupt changes in the values of the solution over very short distances, adaptive mesh techniques can be applied to resolve the high activity regions by ordering grid points in appropriate places. To avoid a control volume formulation of the solution of partial differential equations, a simple orthogonal, adaptive-mesh technique is employed. This involves separate adaptation in the x and y directions. Through simple analysis and numerical examples, the adaptive mesh is shown to give significant increase in accuracy in the computations.

• Journal of Bio-Environment Control
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• v.2 no.1
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• pp.9-15
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• 1993

Chinese white cabbage, Chinese flat cabbage, lettuce, garland chrysanthemum, and green perilla were grown in nutrient solution culture to investigate the effects of various media and nutrient solutions. The culture media were sand, mixed substrate(peatmoss : sand= 1 : 1), and non-media(deep-flow culture). The nutrient solutions were Cooper's, Hoagland's, and Yamazaki's solution. Plants were grown under different treatments for three weeks. Generally, the growth was greatest in non-media culture and followed mixed substrate culture, and poorest in sand culture. In non-media culture, the growth of Chinese white cabbage, Chinese flat cabbage, lettuce, and green perilla was good in Yamazaki's solution. And regardless of nutrient solution, garland chrysanthemum was good in non-media culture. Relative chlorophyll was not different among the treatments.

• Geomechanics and Engineering
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• v.13 no.6
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• pp.1011-1025
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• 2017

The geological conditions surrounding the Jijiapo Tunnel of the Three Gorges Fanba Highway project in Hubei Province are very complex. In this paper, a 3-D physical model was carried out to study the evolution process of filling-type fracture water inrush and mud gush based on the conditions of the section located between 16.040 km and 16.042 km of the Jijiapo Tunnel. The 3-D physical model was conducted to clarify the effect of the self-weight of the groundwater level and tunnel excavation during water inrush and mud gush. The results of the displacement, stress and seepage pressure of fracture and surrounding rock in the physical model were analyzed. In the physical model the results of the model test show that the rock displacement suddenly jumped after sustainable growth, rock stress and rock seepage suddenly decreased after continuous growth before water inrushing. Once water inrush occured, internal displacement of filler increased successively from bottom up, stress and seepage pressure of filler droped successively from bottom up, which presented as water inrush and mud gush of filling-type fracture was a evolving process from bottom up. The numerical study was compared with the model test to demonstrate the effectiveness and accuracy of the results of the model test.

• Korean Journal of Family Social Work
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• no.53
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• pp.199-234
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• 2016

This study deals with the psycho-social development of children raised by disabled parents. In particular, we are willing to examine the influence of parental factors such as social engagement and future forecast on the change of children's psycho-social development. Using the three waves of Korean Welfare Panel Study data, these predictors were examined through the Latent Growth Curve Modeling. The result shows that parent's disability has a negative influence on their children's psycho-social development. However, similar to the findings of the previous studies, the degree of this influence tends to be decreased as children grow up. Lastly, two parental factors have a direct influence on the psychological development of children. Furthermore, parent's social engagement has an indirect influence on the change of sociality of children through the psychological change of them. This result means that we should encourage disabled parents to participate actively in social activities and think positively about their future.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.199-199
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• 2017

Sustainable wheat production is of paramount importance for attaining/maintaining the food self-sufficiency status of the rapidly growing nation of Pakistan. However, the average wheat yield per unit area has been dwindling in recent years and the climate-induced variations in rainfall patterns and temperature regimes, during the wheat growth period, are believed to be the reason behind this decline. Crop growth simulation models are powerful tools capable of playing pivotal role in evaluating the climate change impacts on crop yield or productivity. This study was aimed to predict the plausible variations in the wheat yield for future climatic trends so that possible mitigation strategies could be explored. For this purpose, Aquacrop model v. 4.0 was employed to simulate the wheat yield under present and future climatology of the largest agricultural province of Punjab in Pakistan. The data related to crop phenology, management and yield were collected from the experimental plots to calibrate and validate the model. The future climate projections were statistically downscaled from five general circulation models (GCMs) and compared with the base line climate from 1980 to 2010. The model was fed with the projected climate to simulate the wheat yield based on the RCP (representative concentration pathways) 4.5 and 8.5. Under the worst, most likely future scenario of temperature rise and rainfall reduction, the crop yield decreased and water footprint, especially blue, increased, owing to the elevated irrigation demands due to accelerated evapotranspiration rates. The modeling results provided in this study are expected to provide a basic framework for devising policy responses to minimize the climate change impacts on wheat production in the area.

• Smart Structures and Systems
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• v.28 no.6
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• pp.745-760
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• 2021

Dynamic buckling of structure is one of the failure modes that needs to be considered since it may result in catastrophic failure of the structure in a short period of time. For a thin fiber-reinforced polymer (FRP) plate under compression, buckling is an inherent hazard which will be intensified by the existence of defects like holes, cracks, and delamination. On the other hand, the growth of the delamination is another prime concern for thin FRP plates. In the current paper, reinforcing the plates against buckling is realized by using SMA wires in the form of stitches. A numerical framework is proposed to simulate the dynamic instability emphasizing the effect of the SMA stitches in suppressing delamination growth. The suggested algorithm is more accurate than the other methods when considering the transformation point of the SMA wires and the modeling of the cohesive zone using simple and yet reliable technique. The computational design of the method by producing the line by line orders leads to a simple algorithm for simulating the super-elastic behavior. The Lagoudas constitutive model of the SMA material is implemented in the form of user material subroutines (VUMAT). The normal bilinear spring model is used to reproduce the cohesive zone behavior. The nonlinear finite element formulation is programmed into FORTRAN using the Newmark-beta numerical time-integration approach. The obtained results are compared with the results obtained by the finite element method using ABAQUS/Explicit solver. The obtained results by the proposed algorithm and those by ABAQUS are in good agreement.

• Knowledge Management Research
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• v.23 no.2
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• pp.37-60
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• 2022

The growth of virtual reality games and the popularization of blockchain technology are bringing significant changes to the formation of the metaverse industry ecosystem. Especially, after Meta acquired Oculus, a VR device and application company, the growth of VR-based metaverse services is accelerating. In this study, the concept that supports leisure activities in the metaverse environment is explored realting to game-like features in VR apps, which differentiates traditional mobile apps based on a smart phone device. Using exploratory text mining methods and network analysis approches, 241 apps registed in the Oculus Quest 2 App Store were analyzed. Analysis results from a quasi-network show that a leisure concept is closely related to various genre features including a game and tourism. Additionally, the anlaysis results of G & F model indicate that the leisure concept is distictive in the view of gateway brokerage role. Those results were also confirmed in LDA topic modeling analysis.