38 research outputs found
Study on the arc stability and the weld quality based on the statistical analysis of the arc power and the dynamic resistance
Welding techniques are applied as a major process in the manufacture of most metal structures. In particular, the automotive, shipbuilding and plant industries have been partially automated and are still heavily equipped with manual and semi-automatic welding. In terms of weld quality, the quality and stability of the arc can be considered an important factor in order to produce a designer or a result of a weld meeting specific criteria. However, there is a possibility of weld defects even if these factors fall into the normal category, and when assessing weld quality, they rely on the visual assessments and manual testing through non-destructive testing.
This study performed more than 80 welding times and detected welding current and welding voltage using a welding signal detector during the welding process. After converting the detected signals into data, power and dynamic resistance related to the arc energy intensity were calculated. It is like the energy to melt wires and parent metal, and the arc dynamic resistance is generally associated with arc length and at the same time a constant power is required to meet the desired weld quality, making it an evaluation on weld quality and arc stability. Probability and graph analysis based on the statistical method were then performed by projecting the calculated values onto the current-voltage plane trajectory. The relationship between these results and the results of welding by visual and non-destructive testing was investigated to establish objective and quantitative criteria to assess how the quality and stability of arcs alone affect weld quality. It is judged that this can be easily evaluated by a person who is not a high-function or a non-destructive examination.| μ©μ κΈ°μ μ λλΆλΆμ κΈμꡬ쑰물 μ μ‘°μμ μ£Όμ 곡μ μΌλ‘ μ μ©λλ€. νΉν μλμ°¨, μ‘°μ ν΄μ, νλνΈ μ°μ
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User Experience Design Key Factors of Digital Device for Edutainment - An Analysis on Preschool Childrenβs Behavioral Patterns and Parenting Behavior -
Effect of Mental Model Based Instruction on Student's Conceptual Changes in Circular Motion
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The purpose of this research was to verify the effect of Mental Model based instruction on the student's conceptual changes in circular motion. The Mental Model based instruction was specifically designed to change the student's ontological presupposition and epistemological presupposition. One hundred and nine high school students were randomly assigned to either the treatment group or control group. In the treatment group, the Mental Model based instruction was given. For the control group, traditional lecture type instruction was given. The concepts of circular motion in physics were covered in both instructions. Pretests and Posttests on the concept of circular motion were administered to both groups. In addition, data on the students' cognitive abilities and achievement were collected. The results showed that the students in Mental Model based instruction had more scientific conceptual changes than the ones in the traditional instruction. For the Mental Model based instruction group, the students with most scientific conceptual changes did not differ from the ones without any scientific conceptual changes in terms of their cognitive abilities and achievement. However, for the traditional instruction groups, the students with most scientific conceptual changes showed higher motivation and achievement than the ones without any scientific conceptual changes. The implication of the results were discussed in terms of the application of Mental Model theory in practice