• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.34-39
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• 2001

The median barrier is one of the roadside hardware to prevent severe human and property damage from highway traffic accidents. The foreign standard of concrete median barrier was introduced and implemented without modification fitting to domestic vehicle and highway condition. In a car accident, median barrier doesn't protect vehicle effectively, especially for heavy vehicle such as bus and heavy truck. The purpose of this study is to develop the optimal performance design of concrete median barrier using the design of experiment with crash simulation analysis which is done by Pam-Crash that is one of the commercial crash simulation software. As a result of this study, an optimal design of concrete median barrier is obtained considering von Mises stress, volume and COG acceleration of truck.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.8
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• pp.730-739
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• 2015

In this paper, a wideband circular polarizer operating in the frequency range of 6~18 GHz is designed and fabricated using a multilayer structure with meanderlines. A T matrix expression for the unit structure, which consists of meanderline, dielectric substrate and spacer, was derived using the boundary value solution. A proposed meanderline structure was modeled as an array of unit meanderline cell in order to apply the waveguide model with PEC and PMC boundary conditions. The calculation procedures to obtain an equivalent susceptance of the unit meanderline cell using HFSS was also suggested. Using a hybrid method, which combines the T matrix with the HFSS results, and cut-and-try method, a wideband circular polarizer with low insertion loss and good AR performance was designed. The fabricated polarizer has the return loss less than -10 dB within 92 % bandwidth, the average insertion loss less than -0.24 dB, and the average AR below 2.6 dB for full 3:1 bandwidth.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.1-8
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• 2011

The purpose of this study is to suggest the optimized transfer algorithm of earthwork considering the precluded area such as the lake, bogs. The earthwork transfer plan in massive cutting and banking should be established because of affecting the construction cost highly. Until now, there was the study about the optimized earthwork transfer model considering the OR(Operating Research). but isn't the study about the model considering the precluded area such as the lake, bogs. In most cases, the engineer adjusts the earthwork transfer path considering the precluded area, manually. The presented model suggests to calculate various visibility paths with $A^*$algorithm after converting the precluded area to polygon topology. By using this paths, the minimum cost path to optimize the earthwork transfer can be obtained. In this study, the validity of the model was proved as implementing the system for the optimized earthwork transfer considering the precluded area.

• Journal of the Korean Society for Library and Information Science
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• v.47 no.4
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• pp.103-124
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• 2013

This study investigated how Problem-Based Learning method effects on students' Self-Regulated Learning Strategies especially for the LIS education. For this purpose, the differences in students' self-regulated learning strategies were examined as a pre and a post survey using the same questionnaire. Correlation between cognitive and motivational self-regulated learning strategies was examined, and the details of the SRL's sub-components were measured to see the effects of Problem-based learning. Statistical significance using the paired sample t-test were also conducted. The results revealed that Problem-based learning is effective in improving students' cognitive motivational self-regulated learning and found out the possibilities for a follow-up study for motivational self-regulated learning.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.240-244
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• 1999

Monolithic SiC and SiC/C functionally gradient material (FGM) layers were deposited on graphite substrates by CVD method. Temperature a profiles and thermal stress distributions in the deposited layers under the thermal shock were calculated by a commercially available software package. The designed FGM specimens were found to show an efficient relaxation of thermal stresses at the interfaces, and the specimens were intact even under a thermal shock of $\Delta$T=1600 K.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.487-492
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• 2002

In this study, designs of protection fences such as the concrete median barrier and the guardrail were performed. The foreign standard of concrete median barrier was introduced and implemented without modification fitting to domestic vehicles and highway conditions. In a car accident, median barrier doesn't protect vehicles effectively, especially for heavy vehicles such as bus and heavy truck. Guardrail doesn't protect vehicle effectively, either. The purpose of this study is to develop the optimal performance design of concrete median barrier and design of guardrail using the design of experiment as well as crashworthiness analysis which is done by Pam-Crash. As a result of this study, an optimal design of concrete median barrier was obtained considering von Mises stress, volume and COG acceleration of truck. And design of guardrail satisfying the domestic requirements was obtained.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.5
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• pp.80-90
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• 1998

The EPS construction method-one kind of the load reducing methods-utilizes the EPS blocks, ultra-light materials whose unit weight is about 1/100 of soils and has been applied to many soft ground sites. It needed 3,000 days to get the 90% degree of the consolidation for the case of 12m high soil embankments on the 30m thick soft clayey foundations. The N value of SPT at this deposit was less than 5. The pack drain was installed to promote the radial consolidations. Although staged embankments were planned, designers failed to get a sufficient stability of the foundation ground. Therefore, the EPS fill method was selected to reduce the load and the construction period. EPS blocks(D-20 model) replaced the upper part of the soil embankments. These complex embankments reduced the ground settlement and the construction period. The possibility of lateral movements of the bridge abutments was checked and the design scheme was reviewed.

• Journal of Industrial Convergence
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• v.21 no.3
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• pp.107-115
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• 2023

This study was conducted to test the effect of flipped learning on academic self-efficacy, achievement goal, cognitive engagement of nursing students. This study used a one group pre-post test design. Participants were 91 students who were taking the health and physical assessment in nursing. The flipped learning was provided for 5 times (10 hours). The data of 91 people who agreed to the study and responded to the pre and post questionnaires were analyzed. Data were collected between September 26 and November 25, 2022. Data were analyzed by frequencies, paired t-test using SPSS WIN 24.0. The results showed that self-efficacy of learning(t=-5.445, p<.001), and cognitive engagement(t=-2.120, p=.035) increased significantly. As a result of the study, it was proved that flipped learning is effective for self-efficacy of learning and cognitive engagement. But it is necessary to conduct repeated studies due to limitations in research design, and to explore ways to utilize various teaching-learning strategies to improve the learning ability and clinical performance of nursing students.

• KIISE Transactions on Computing Practices
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• v.23 no.12
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• pp.684-690
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• 2017

Researchers have suggested several methods for utilizing various kinds of services in an Internet of Things (IoT) environment. These methods require users to learn some new kinds of tools or expertise in programming. In this paper, we propose a new paradigm, which allows end-users to build IoT-service mashups based on a presentation-authoring scheme. We have also included a framework for this procedure. The design of a mashup model in this framework was based on a task-oriented service framework. Users can build a mashup of this framework in the presentation-file format, convert it into a service flow, and deploy it for running in an IoT environment. In addition, we use a case study to show how PowMash supports end-users' service mashups in an IoT environment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.26-32
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• 2016

Usually, there are many uncertainties regarding the error of an assumed load, material properties, member size, and structure analysis in a structure, and it may have a direct influence on the qualities of optimal design of structures. Probabilistic analysis has developed rapidly into a desirable process and structural reliability analysis is an increasingly important tool that assists engineers to consider uncertainties during the design, construction and life of a structure to calculate its probability of failure. This study deals with the applications of two optimization techniques to solve the reliability-based optimization problem of structures. The reliability-based optimization problem was formulated as a minimization of the structural volume subject to the constraints on the values of componential reliability index determined by the AFOSM approach. This presented method may be a useful tool for the reliability-based design optimization of structures.