• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.1
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• pp.17-23
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• 2017

This study is about the development and revision of a blower design for a ventilation system. In this study, to describe the flow in the 4000CMM grade blower, 3-dimensional steady-state turbulence was assumed to govern the flow equation. The flow field with velocity distribution according to the elbow duct of the ventilation system is also compared. Finally, vibration was observed in the blower at the installation to ventilation system. The cause was due to a problem in the manufacturing process of the airfoil type impeller.

• Journal of Korean Library and Information Science Society
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• v.47 no.3
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• pp.1-20
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• 2016

The purpose of this study is to analyze inquiry tasks of social studies textbooks of the first term focused on the information literacy process and find out teacher librarians' educational information services in elementary schools. Results of the analysis show that there are 69 inquiry tasks. Among them 60 tasks are individual tasks. Within the information literacy process, the 4th grade students seem to resolve their tasks by researching or investigating resources, arranging and presenting the results of inquiry individually. The 5th and 6th grade students could read visual materials written in the text books to perform the individual inquiry tasks and present their results orally. So teacher librarian can help students judge proper information resources of the second step, order the found information of the 3rd step and evaluate the results and process of 4th step under the information literacy process.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.429-434
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• 2001

Rail crossings pose special safety concerns for modern railroad operation with faster trains. More than ninety percent of train operation-related accidents occurs on at-grade crossings. Surest countermeasure for this safety hazard is to eliminate at-grade crossings by constructing over/under pass or by closing them. These eliminations usually require substantial amount of investment and/or heavy public protest from those affected by them. Thorough and objective analysis are usually required, and valid accident prediction models are essential to the process. This paper developed an accident prediction model for Korean at-grade crossings. The model utilized many important factors such as guide personnel, highway traffic, train frequency, train sight distance, and number of tracks. Developed model was validated with actual accident data.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.5
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• pp.773-781
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• 2004

This research was Performed to raise grade efficiency of Sturtevant type air classifier. to treat powder less than $74\mu\textrm{m}$ particle produced at the crushing process of the dry aggregates manufacturing system or concrete wastes recycling system. The experimental conditions were in the ranges. 0.85 to 5.15 $m^3$/s of primary air flow rate. 0.005 to 0.015 $m^3$/s of secondary air flow rate $30^{\circ}$ to $70^{\circ}$ of auxiliary blades angle. respectively. for 1.7~3.3 kg/min of the powder feed rate. It was found that the grade efficiency of the air classifier was increased as the baffle plate was attached at the expansion region. and the optimal operating conditions of the air flow rates and the blade angle were obtained. The fractional recovery curves from the experiments were well agreement with the theoretical one of Molerus model.

• Journal of Industrial Technology
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• v.27 no.A
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• pp.31-38
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• 2007

Recently produced concrete has a tendency to overcome environmental defects. Porous and planting Eco-concrete requires the neutralization process and enough void in concrete to contain water, to pass air freely, and provides necessary nutrients to vegetation roots. The biological environment in concrete is not suitable for planting because the concrete possesses strong alkali constituent of pH 11-13. This study evaluated the strength and serviceability of concrete as well as the chemical characteristics of concrete mixed by low-grade iron ore left in the abandoned mine and treated by Ammonium monohydrogen phosphate, $(NH_4)_2HPO_4$. Test variables include two kinds of coarse aggregates such as crushed stones and low-grade iron ore, the duration time and the period for neutralization treatment by Ammonium monohydrogen phosphate, $(NH_4)_2HPO_4$, and the proportion ratio of cement, blast furnace slag and silica fume.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2004.11a
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• pp.212-220
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• 2004

In this work the Dynamic Matrix Control method is applied to control the grade change operations in paper mills. Paper process trained by neural network regards a real-plant. The model obtained with operation data is used to achieve DMC. Results of simulations for DMC control of grade change operations are compared with plant operation data response. From the comparison, we can see that the proposed DMC method exhibits faster response for the grade change of paper and achieves stable steady-state.

• International Journal of Highway Engineering
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• v.15 no.4
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• pp.177-186
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• 2013

PURPOSES: The purpose of this study theoretically reviews vertical grade deriving process in super high speed environment and compares overseas design criteria with Domestic Standardization also draws suitable vertical grade design criteria of high standard for Domestic Circumstances in Korea. METHODS : By researching domestic vehicle registration status, calculating typical vehicle, using Vissim which is traffic simulation program, Speed-distance curve of the vehicle is derived under each design speed condition. Through Speed-distance curve, estimating critical length of grade and considering critical length of grade, maximum longitudinal incline is proposed. RESULTS : The result of domestic vehicle registration status, the typical vehicle for deriving vertical grade is calculated based on gravity horsepower ratio 200 lb/hp. For calculating critical length of grade, according to change speed of uphill entry, speed-distance curve is derived by using Vissim. Critical length of grade is calculated based on design speed 20 km/h criteria which is point of retardation. Estimated critical length of grade is 808 m and based on this result, maximum longitudinal incline was confirmed in the design speed between 130km/h to 140km/h. CONCLUSIONS: The case of the typical vehicle(truck) which is gravity horsepower ratio 200 lb/hp, maximum longitudinal incline 2% is desirable at the super high speed environment in the design speed between 130km/h to 140km/h.

• The Journal of Korean Association of Computer Education
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• v.16 no.4
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• pp.13-21
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• 2013

Recently, programming education is being actively performed in education field with development of educational programming language and teaching and learning methods for elementary students. However, programming education have limit to apply to the overall computer science curriculum, because it is performed by more than 5th grade and focused on the utilization of programming tools than problem-solving process. It is necessary to expand the range of students and educational content considered with problem-solving process for encouraging programming education in computer science. In this study, we suggest the easy-to-use programming tool for lower grade(1st grade) and robot programming task based on improvement of student's thinking ability. We use Tangible User Interface(TUI) for elementary student's(1st grade) convenience of programming and developed the robot programming task for improvement of logical thinking. As a result of this experiment, tangible programming tool can be used easily in elementary students(1st grade) and developed robot programming task is effective in improvement of logical thinking.

• Proceedings of the KWS Conference
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• 1997.05a
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• pp.57-59
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• 1997

• Hwankyungkyoyuk
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• v.20 no.4
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• pp.84-96
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• 2007

The purpose of this study is to develop instruction model of environmental problem process focused with environmental justice. This study has analyzed environmental problem solution process in social studies of elementary school from 4th grade to 6th grade with it. The results of this study are as follows. First, social studies of elementary school didn't show distributive justice in environmental problem solving process. Second, procedural justice existed, but offered information is lacking to each main group. Third, substantive justice was emphasized personal viewpoint. We developed instruction model of environmental problem solving process based upon the results. Component of instruction model is problem analysis, distributive justice, procedural justice, substantive justice and evaluating a solution. Timely, teachers can use and can apply it in social studies class. In conclusion, it is strongly recommend to teach environmental education linked with environmental justice. It enables us enhance a new awareness and attitudes towards sustainable development.