• Journal of Korean Home Economics Education Association
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• v.17 no.4 s.38
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• pp.87-100
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• 2005

The Purpose of this study is to understand on the whole trend in the home economics instructions among the middle school. The study has been achieved through observing the actual classroom activities, and stating the results as objective as possible. In as much as clarifying the objectives of observing the classroom activities, it would be deemed effective to understand the overall outline of the home economics instructions, as well as to define the elements that make up the classroom work. Hence, the classroom work has been modularized in stage, namely. planning/organization, execution, and evaluation, as well as extracting nine(9) elements of the classroom work. Video-taped classroom activities, which have been used for this research analysis, consists of twelve(12) study classes, covering the subjects in food/nutrition, clothing, household management, daily life as a consumer, and housing management. The items in the study the items of checklist have been broken down further in an effort to develop a framework for analyzing the results of observing the classroom activities. Also included, in part, is the verbatim transcription of the videotaped classroom activities in progress.

• Journal of the Korean Geotechnical Society
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• v.36 no.4
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• pp.5-15
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• 2020

This paper proposes a revised Modified Cam Clay type failure surface based on the critical state theory. In the plane of the mean effective and von Mises stresses, the original Modified Cam Clay model has an elliptic failure surface which leads the critical-state mean effective stress to be always half of the pre-consolidation mean effective stress without hardening and evolution rules. This feature does not agree with the real mechanical response of clay. In this study, the preconsolidation mean effective stress only reflects the consolidation history of the clay whereas the critical state mean effective stress only relies on the currenct void ratio of clay. Therefore, the proposed failure surface has a distorted elliptic shape without any fixed ratio between the preconsolidation and critical state mean effective stresses. Numerical simulations for various clays using failure surfaces as yield surface provide mechanical responses similar to the experimental data.

• Journal of the Korean Geosynthetics Society
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• v.12 no.1
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• pp.11-19
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• 2013

Coarse-grained soils are typical engineering materials commonly used in many civil engineering applications such as structural fills, subgrade and drainage fills for dam, railway and bridge. Various researches have been performed with related to constitutive laws for numerical analysis of such structures. This paper presents a parametric study for a constitutive model for coarse grained materials. The model is a kind of the bounding surface models based on critical state theory. A distinct feature of the model is to capture the response of coarse-grained materials with different void ratios and confining pressures using a single set of model parameters. The model behavior is defined with a set of elastic parameters, critical state parameters, and model-specific parameters. The parametric study was performed for the model-specific parameters. The result of parametric study shows that the model is capable to capture stress-dilatancy behavior and kinematic-hardening under non-associative plastic flow.

• The Journal of the Korean dental association
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• v.22 no.7 s.182
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• pp.621-633
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• 1984

The possibility of expanding the linear range of the Kinesiograph was studied using a nonferromagnetic mechanical positioning device. The magnet was moved in linear steps of 5 mm through three planes parallel to the frame work carrying the sensors within working range of a 3 cm wide by 4 cm deep by 5 cm high three dimensional lattice and a matrix of 693 data points was achieved. For each data point, the three Kinesiograph outputs were associated with the values of actual position. Once three coordinates of observed values were known, actual values could be determined. A computer program was specially written in Fortran to deal with this work. Because each dat point was 5 mm apart from each other, there would be 480 cubes with 8 data points Further refinement of the system is possible using a smaller interval between each data point. In conclusion, a theoretical model was presented which, by means of computer support, would allow the absolute measurement of jaw position over the entire range of functional jaw movements.

• Journal of the Korean Chemical Society
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• v.60 no.4
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• pp.267-275
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• 2016

Experiment is recognized as an important part in science and science education. Scientists do experiments for verifying or refuting theory and they take many forms to do experiments. One of the central goals of science education is to improve inquiry ability. So we have taken for granted that students engage in authentic inquiry and experiment which scientists carry out to research. But it is not always positive about discussions and opinions what school experiment and its role is in learning science and understanding about science. There is certainly a gap between experiments which scientists and students do even though there is a theoretical basis of school science experiment. In this study, we discussed how scientific inquiry and school inquiry are different, and what it means to use instrument in school science experiment. And as a case, we analyzed chemistry experiments in science textbook and manipulation level of instruments which were handled in chemistry experiments, we shed light on the meanings of experiments and instruments in school science inquiry based on the result of experiments and instruments analysis.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.5
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• pp.829-837
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• 1992

This paper presents a new approach for the analysis of hot strip rolling processes. The approach is based on the finite element method and capable of predicting velocity field in the strip, temperature field in the strip, temperature field in the roll, and roll pressure. Basic finite element formulations for heat transfer analysis are described with emphasis on the treatment of numerical instability resulting from a standard Galerkin formulation. Comparison with the theoretical solutions found in the literature is made for the evaluation of the accuracy of the temperature solutions. An iterative scheme is developed for dealing with strong correlations between the metal flow characteristics and the thermal behavior of the roll-strip system. A series of process simulations are carried out to investigate the effect of various process parameters including interface friction, interface heat transfer coefficient, roll speed, reduction in thickness, and spray zone. The results are shown and discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5412-5419
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• 2011

The need is growing for high-speed spindle because various equipment are becoming more precise, miniaturization and high speed with the development of industries. Air-lubricated dynamic bearings are widely used in the optical lithographic manufacturing of wafers to realize nearly zero friction for the motion of the stage. Air-lubricated dynamic bearing can be used in high-speed, high-precision spindle system and hard disk drive(HDD) because of its advantages such as low frictional loss, low heat generation, averaging effect leading better running accuracy. In the paper, numerical analysis is undertaken to calculate the performance of air-lubricated dynamic bearing with herringbone groove. The static performances of herringbone groove bearings which can be used to support the thrust load are calculated. Electrochemical micro machining($EC{\mu}M$) which is non-contact ultra precision machining method has been developed to fabricate the air-lubricated dynamic bearing and optimum parameters which are inter electrode gap size, concentration of electrolyte, machining time are simulated using numerical analysis program.

• Journal of the Korean Institute of Gas
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• v.19 no.6
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• pp.47-53
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• 2015

This paper is to study applying for numerical analysis method for flow field, velocity and pressure of fuel on the low pressure pump using excavator. The pressure distribution of fuel pump certified the linear variation according to rotation angle of rotor. Especially, it knew the fact that the pressure in rotation angle $40^{\circ}$ appeared high outlet and low inlet of fuel pump. Also, this range angle can seek the fact that the leakage flow and velocity are the most increasing. And the more rotor rotation of fuel pump, the more mean outlet flow rate increased in linear. Whenever the gap size decrease with rotor and housing, the discharge flow rate could seek the approaching 0.0712kg/s that consider with theory discharge flow rate calculated from displacement between rotor gear and idle gear.

• Journal of the Korean Geotechnical Society
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• v.22 no.4
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• pp.73-83
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• 2006

Seepage analysis through unsaturated zone based on the theory of unsaturated flow is commonly performed to evaluate dam safety. However, the concepts of unsaturated soil behavior have not been transferred into the hands of practicing geotechnical engineers since the problems involving unsaturated soils often have the appearances of being extremely complex. There is variability and uncertainty associated with the unsaturated hydraulic properties that in turn will lead to variability in predicting unsaturated soil behavior such as seepage rate and the pore water pressure distribution. In this paper, measurements of the soil-water characteristic curve and saturated hydraulic conductivity for the core material of dam were conducted. Then, finite element stochastic analysis was used to capture the effect of unsaturated hydraulic properties on the seepage behavior of dam. It is observed that the amount of seepage increases, as the values of unsaturated soil parameters a and n increase. The values of m and p showed opposite trend.

• Journal of the Korean GEO-environmental Society
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• v.25 no.5
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• pp.15-19
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• 2024

This study aimed to develop high-efficiency grouting techniques under deep-depth conditions by experimentally verifying the applicability of various injection materials. Particle size analysis and injection model experiments were conducted with Ordinary Portland Cement (OPC) and Micro Cement (MC) to evaluate the injection performance of each material. Using Barton's Cubic Network theory, the rock fracture spacing was calculated for domestic deep-depth standards, specifically below 40 meters underground. The analysis of particle size passability under selected conditions showed that MC could pass through the rock fracture gaps, while OPC could not. According to the results of the injection model experiments using experimental devices and area calculation software, OPC failed in injection due to its larger particle size, whereas MC was capable of injection even under high-viscosity conditions. Based on these findings, the study quantitatively and visually derived the applicability of grouting materials under deep-depth conditions, and high-viscosity MC material is expected to be effective for waterproofing enhancement in deep-depth rock fracture surfaces.