http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
교육효율화를 위한 교육공학의 적용에 관한 연구 - 체제적 수업을 중심으로 -
김경애(K . A . Kim),강춘식(C . S . Kang),라형용(H . Y . Ra) 대한공업교육학회 1983 대한공업교육학회지 Vol.8 No.2
The purpose of this study was to compare the effect of the traditional instruction with that of the systematic instruction upon the concepts and principles learning in engineering students. Mainly the traditional instruction was sequenced according to the "logic" of the content. The traditional instruction groups were divided into two groups-lecture group and sound slides group which have proceeded the same insttuctional events. The systematic instruction was sequenced according to the learner characteristics, learning tasks, and media characteristics. The results of the present study showed that the research hypotheses were generally accepted. The systematic instruction group scored significantly greater than the traditional instruction groups (lecture group and sound slilds group) in the achievement test. Through the attitude and response test, it showed that the systematic instruction was more effective than the traditional instruction on the short-term memory and understanding and applying the concepts and principles. Almost every student attended this experiment wanted to use of instructional media on other units of foundary engineering and other subjects.
7075 Al 합금/SiCP 복합재료의 마멸특성 (1) : 상온 및 고온 마멸거동 Wear behaviour at room and elevated temperature
라형용,오창선,이영근 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.2
Wear characteristics of 7075 Al/SiC_p composites fabricated by spray forming and extrusion process are studied. This study shows a wear transition from mild to severe wear as a function of applied load, sliding velocity and friction temperature with wear mapping approach. 7075 Al/SiC_p composites exhibit the transition from mild to severe wear when a load, sliding velocity or temperature reaches a critical value respectively. In mild wear regime; wear rate increases with increasing applied load. But wear rate decreases with increasing sliding velocity. At constant load and velocity in mild wear conditions, wear rate decreases with increasing friction temperature. The reasons are that the worn surface of disk was covered with much more iron oxides at elevated temperatures than at room temperature which played a role as solid lubricant. But in severe wean regime, this oxide layer is not stable and fractured, leading to increase wear rate and friction coefficient. Wear transition map of 7075 Al/SiC_p composites is constructed on applied load and sliding velocity axes with elevated temperatures. Severe wear regime is enlarged with increasing temperature on the wear transition map and wear transition conditions move to lower load and velocity at elevated temperatures than at room temperature. Therefore safe operating range of aluminum metal matrix composite parts is reduced at elevated temperatures.
과공정 Al-Si 합금의 분무성형-압출에 따른 미세조직 변화
라형용,이호인,김상균,석현광,이재철,신돈수 대한금속재료학회(대한금속학회) 1998 대한금속·재료학회지 Vol.36 No.10
Microstructural evolutions of both Si particles and matrix grains of hypereutectic Al-Si alloy were investigated by calculating temperature profiles within the preform during spray forming. Based on calculations, the cooling rates were observed to be relatively higher both at the bottom and the top than the inner regions of the preform along the rotation axis of rod. Such trends in temperatures resulted in size variations of Si particles within the preform. The size of Si particles varies from 3㎛ to 13.5㎛ with distance from the surface to the inner of the preform along the rotation axis of rod. Larger Si particles observed from the inner regions of the preform were found to be poly-crystals having irregular surface boundaries. However, such Si particles were fractured after extrusion, indicating a possibile means for fabricating hypereutectic Al-Si alloys with fine Si particles. In addition, the methodology for predicting the matrix grain size in the presence of small Si particles was also demonstrated.