• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.677-684
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• 2012

In recent years, extension of life span of buildings is becoming an important issue in our society. To improve the life span of buildings, rhamen structure construction and long-spanned structures are advantageous. And in order to achieve this goal, structural elements of buildings must be light and slender. As an alternative method, general porous slabs are used frequently domestically and internationally. But the study on the porous slabs using T-deck plate and assembly of light weight precast construction is insufficient at present. In this study, flexural and fatigue tests were performed on six specimens to verify structural performance and serviceability. The main parameters of the specimens were light weight and T-deck plate construction possibility as well as slab thickness. The test results indicated that the strength of porous slabs using T-deck plate and assembly of light weight were much better than general RC slabs and porous slabs without T-deck plate. And stiffness was much better than that of other tested slabs.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.3
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• pp.171-178
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• 2020

In this study, we develop MPI-OpenMP hybrid parallelization for multibody peridynamic simulations. Peridynamics is suitable for analyzing complicated dynamic fractures and various discontinuities. However, compared with a conventional finite element method, nonlocal interactions in peridynamics cost more time and memory. In multibody peridynamic analysis, the costs increase due to the additional interactions that occur when computing the nonlocal contact and ghost interlayer models between adjacent bodies. The costs become excessive when further refinement and smaller time steps are required in cases of high-velocity impact fracturing or similar instances. Thus, high computational efficiency and performance can be achieved by parallelization and optimization of multibody peridynamic simulations. The analytical code is developed using an Intel Fortran MPI compiler and OpenMP in NURION of the KISTI HPC center and parallelized through MPI-OpenMP hybrid parallelization. Further parallelization is conducted by hybridizing with OpenMP threads in each MPI process. We also try to minimize communication operations by model-based decomposition of MPI processes. The numerical results for the impact fracturing of multiple bodies show that the computing performance improves significantly with MPI-OpenMP hybrid parallelization.

• Journal of Gifted/Talented Education
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• v.27 no.1
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• pp.97-118
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• 2017

This paper aims to provide reference model for directions and objectives of Software(SW) gifted education. In order to achieve the goals introduced above, we conducted the research in the following steps. First, we selected the concept of ICT-based creative talented person as a base model to establish the concept of SW gifted person. The selected base model composed three core competencies which were 'knowledge and technology competencies', 'synthesizing and creativity competencies', and 'personality competencies'. Second, we developed survey tools, like questionnaires, to investigate participant's recognition of SW gifted person. The survey tools composed three components 'computational thinking', 'entrepreneurship', and 'social responsibility'. Each of the components composed seven elements. Third, after selecting the opinion poll participants as an elementary school teacher, we surveyed opinion polling. By selecting an elementary school teacher as the opinion poll participants, we wanted to identify theirs ' opinions which are thought to be the starting point for gifted education. To survey we developed on-line survey system by using Google functions. Fourth, we analyzed the collected opinion data. To identify we summarized and synthesized participant's opinions that average values and agreement level by using frequency analysis. Also, in order to compare opinions that average values and agreement level based on whether or not participant's various experiences and competencies we computed t-value, F-value, and ${\chi}^2$ verification.

• Current Research on Agriculture and Life Sciences
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• v.7
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• pp.117-125
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• 1989

This study was carried out to investigate the effect of hot water immersion treatment on the control of white tip nematode (Aphelenchoides besseyi) in rice seeds. Disease incidence and yield losses induced by white tip nematode were alos investigated in association with resistance of various rice cultivars. The hot water immersion treatment of rice seeds at $61^{\circ}C$ for 10-15 minutes was effective for the control of the white tip nematode. The stem of most Japonica-type cultivars was damaged by white tip nematode. The Tongil-type cultivars, however, were not infected by the nematode at all. Diseas incidence of Japonica-type cultivars, Odaebyeo and Bogkwangbyeo were 95.6% and 81.8%, respectively. The number of nematodes in infected rice seeds of both Japonica-type and Togil-type cultivars was over 100 per 10gr rice seeds. Although Tongil-type cultivars didn't show white tip symptoms, the yield loss was found in many cultivars. The yield was reduced by 40% Japonica-type cultivars, Odaebyeo and Bogkwangbyeo that were infected by white tip nematode. The yield loss in Japonica-type cultivars was more severe than that in Tongil-type cultiveas. The resistance of Youngdege 5 was highest than any other cultivars showing no disease symptoms and yield loss.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.181-186
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• 2011

Green manure crops are primarily used to reduce the application of chemical fertilizers. In this study, a two-year field experiment was conducted to evaluate the effects of green manure hairy vetch on rice growth and saving of irrigation water. This experiment was conducted at Sinheung series (fine loamy, mixed, nonacid, mesic family of Fluvaquentic Endoaquepts) from 2008 to 2009 at the National Institute of Crop Science (NICS), RDA, Suwon, Gyeonggi province, Korea. Hairy vetch as a green manure crop was incorporated in soil for rice cultivation. Chemical fertilizers had not been applied to hairy vetch plot. Treatments included once irrigation (OI) per week and conventional irrigation (CI). In 2008, the water use efficiency of OI increased by 46% compared to CI by hairy vetch application during rice cultivation season (water treatments were started 38 days after rice transplanting). In 2009, the water use efficiency of OI increased by 61.3% compared to CI by hairy vetch application during rice cultivation season (water treatments were started 30 days after rice transplanting). Soil physical properties such as bulk density, soil porosity ratio and glomalin contents were improved by the incorporation of hairy vetch. The rice yield of OI water management was not significantly different from those of CI water management by hairy vetch application both years. These results suggest that the OI water management with hairy vetch incorporated in soil for rice cultivation can be used in rice fields to reduce the amount of irrigation water and chemical fertilizer.

• The Journal of the Korea institute of electronic communication sciences
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• v.1 no.1
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• pp.56-62
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• 2006

Currently, Most of the Backhual and Submarine's networks are being installed using DWDM and EDFA to deal with dramatically increasing internet traffic. In a conventional type optical system, the so-called 3R repeater, fiber non- linearity was not significant factor but it is one of the most important consideration when designing new DWDM network based on the EDFAs. To minimize the signal pulse distortion in long-haul optical network, Zero-dispersion fiber is indispensable but causes the fiber non-linearity. Therefore this conflicting problems should be managed to transmit a high-speed capacity traffic. In this paper, key technologies in DWDM submarine optic network were found out for a high capacity traffic and introduced the dispersion management way for solving the conflicting problems between Zero-dispersion and non-linearity. Lastly designed a dispersion map in section between Korea and Hong-kong.

• Journal of the HCI Society of Korea
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• v.1 no.1
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• pp.81-88
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• 2006

With the introduction of the digital technology in the exhibition environment, the information of the exhibit has come to be transmitted through diverse media. The visitors desire has been increased from the simple viewing of the exhibition to the active participation in the exhibition viewing and the utilization of the exhibit information. Subsequently, the study on the service to effectively support the viewing experience and provide the information by utilizing the internet and mobile device for visitors in movement has become important in terms of the exhibition environment. Accordingly, in this study, the current condition in studying the service supporting the exhibition environment and the exhibition viewing, which are being changed into a digital network environment, was examined through the literature and case studies. In order to find out the viewing situation and viewing type of visitors, the visitors behaviors of viewing the exhibition were observed. By analyzing the contents observed, the viewing type and keyword were drawn in accordance with the visitors behaviors of viewing. On the basis of this, visitors needs and problems occurring in case of the exhibition viewing were found out via in-depth interview. The service factors of supporting the exhibition viewing were proposed on the basis of the factors by which visitors needs and problems could be solved via interface in the circumstance when visitors would move round the exhibition hall and view the exhibition. In terms of the service factors, the method to resolve was presented on the basis of the relationship between the exhibit and the space in case of selecting and viewing the exhibit. This was applied into the mobile PDA with the example of the exhibition environment in the national museum. Through the scenario of using, the usefulness of the service proposed and the relevant possibility of utilization were reviewed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.4
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• pp.353-358
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• 2011

In this paper, we describe a process for optimally designing a ring-type permanent magnet thrust bearing. The bearing consists of two sets of permanent magnet rings. One set is located inside the other set. An axial offset between the two sets creates axial force, which results in a thrust bearing function. In order to realize an optimal design of the bearing where the required load capacity of the bearing is achieved with the least magnet volume, we derived analytical design equations by adopting the equivalent current sheet (ECS) method. We considered the following two types of magnet arrays: axial arrays and Halbach arrays. These two types of arrays are optimized using the analytical design equations. The results of the optimization are verified using three dimensional (3D) finite element analyses (FEA). The results show that the Halbach array can achieve the required load capacity with less amount of permanent magnet than the axial array does. The efficacy of the ECS method is also verified by using 3D FEA. It is found that the accuracy of ECS method is more sensitive to the underlying assumptions for the Halbach array than for the axial array.

• The Journal of the Korea Contents Association
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• v.5 no.5
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• pp.316-324
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• 2005

e-Learning has been mushrooming with wide range of teaming groups from pedagogy to andragogy As e-teaming opportunities increase, many people raise question about whether e-teaming show positive teaming effects. The related research emphasized that e-learning would be a failure in terms of understanding of e-Learners and activating intuitive teaming activities from learner's long-term memory span. The e-teaming strategies based on the traditional classroom and resulted boring and ineffective teaming outcomes, should be changed to provide authentic and effective teaming results. This paper analyzed that how learners have received e-Learning for the last few years from the research and explained what could be the failing aspects in e-Learning. To be successful, e-loaming should consider the e-learner's individualized teaming style and thinking patterns. When considering of various e-Learning components, the quality of e-teaming should not be focused on any specific single factor, but develop every individual factor to be integrated into high level of quality. In conclusion, this paper suggest that it is needed new understandings of e-Loaming and e-Learner. Also the e-Learning strategies should be examined throughly whether they are on the side of learners and realized how they learn from e-Learning. Finally, we should add enormous imagination into e-loaming for next generation because new generation's teaming patterns significantly differ from their parent's generation.

• Information Systems Review
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• v.18 no.2
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• pp.59-77
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• 2016

Although various recommendation techniques have been applied to the e-commerce market, few studies compare the intent to use these techniques from the customer's perspective. In this paper, we conduct a comparative analysis of customers' intention to use five recommendation techniques widely adapted by online shopping malls and focus on the differences in purchasing electronic goods and apparel products. The recommendation techniques are as follows: best-seller recommendation, merchandiser recommendation, content-based recommendation, collaborative filtering recommendation, and social recommendation. Additionally, we examine which factors influence customer intent to use the recommendation services. Data were collected through a survey administered to 220 e-commerce users with prior experience with recommendation services. Collected data were examined using analysis of variance and regression analysis. Results indicate statistically significant differences in customers' intention to use recommendation services according to the recommendation technique. In particular, the best-seller recommendation technique is preferred when purchasing electronic goods, whereas the content-based recommendation technique is preferred for apparel purchases. Factors such as personal characteristics and personality, purchasing tendency, as well as perception of the product or recommendation service affect a customer's intention to use a recommendation service. However, the influence of these factors varies depending on the recommendation technique. This study provides guidelines for companies to adopt appropriate recommendation techniques according to product categories and personal characteristics of customers.