Metal additive manufacturing (AM) has transformed conventional manufacturing processes by offering unprecedented opportunities for design innovation, reduced lead times, and cost-effective production. Aluminum alloy, a material used in metal 3D printing, is a representative lightweight structural material known for its high specific strength and corrosion resistance. Consequently, there is an increasing demand for 3D printed aluminum alloy components across industries, including aerospace, transportation, and consumer goods. To meet this demand, research on alloys and process conditions that satisfy the specific requirement of each industry is necessary. However, 3D printing processes exhibit different behaviors of alloy elements owing to rapid thermal dynamics, making it challenging to predict the microstructure and properties. In this study, we gathered published data on the relationship between alloy composition, processing conditions, and properties. Furthermore, we conducted a sensitivity analysis on the effects of the process variables on the density and hardness of aluminum alloys used in additive manufacturing.

Alane(aluminum trihydride, AlH3)으로 명명되는 고에너지 물질인 삼수소알루미늄은 수소저장 물질로서 뿐만 아니라 우주항공분야의 고체 추진제나 방위산업의 화약제조용으로도 사용될 수 있다. 본 연구는 습식공정을 통하여 합성하고, 에테르를 세밀하게 분리하는 결정화 공정을 통하여 최종 수소화물을 추출하였다. 결정화 공정에서 삼수소알루미늄-에테레이트(AlH3·(C2H5)2O)가 alane으로 상변이하면서 입자가 성장하고, 85℃에서 2 시간의 결정화 시간이 이루어졌을 때 가장 안정된 결정상이 나타나는 모습을 확인하였다. 최종적으로 추출된 고체상 삼수소알루미늄은 막대모양의 γ-형태가 가장 많은 양을 차지하는 것으로 나타났으며, 크기는 50-100 μm 수준이었다

This study aims to investigate the physicochemical properties of extruded Biji. As the extrusion process variables, the barrel temperature and the moisture content were adjusted at barrel temperatures of 120, 140, and 160°C and 35, 45% respectively. L-value (lightness) increased as the moisture content and barrel temperature increased from 35% to 45% and 120°C to 160°C. In contrast, decreasing a-value and b-value resulted in increasing moisture content and barrel temperature. Total sugar, DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging activity, ABTS (2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)) radical scavenging activity, and total phenolic compound were increased by the extrusion process. The water solubility index (WSI) and dietary fiber of the extruded biji decreased to 3.9% and 592.6 mg/g compared to the non-extruded biji of 12.3% and 592.6 mg/g. According to the result of this study, the extruded biji could be used in various kinds of food processing, and future study is needed to find the optimum condition of the extrusion.

The objective of this study was to determine the effect of moisture content(45, 50, 55%), barrel temperature(140, 150°C), screw speed(150, 250 rpm) and two die configurations on the physical properties of extruded soy protein isolate(SPI). Water holding capacity(WHC), texture, integrity index and nitrogen solubility index(NSI) of extruded SPI were analyzed. The texture of extruded SPI was affected by the die configuration. The physical properties of extruded SPI was significantly influenced by barrel temperature, moisture content and die configuration. The increase in water injection rate and barrel temperature led to increase WHC and NSI. The higher water injection rate led to increase integrity index and texture(elasticity, cohesiveness, chewiness, cutting strength). The extruded SPI at 8 cm die configuration had higher integrity index than those of the 5 cm die configuration. Integrity index and NSI were negatively correlated. Thus, the die configuration can be useful to control quality of extruded SPI.

This study describes how Korean college students perceive reviewing their peers’ drafts over the course of one semester and what variables might affect their review process. Twenty-six students enrolled in the teacher researcher’s two writing courses participated in this study. The data came from the students’ reflections on their peer reviews and the researcher’s observations/descriptions of the review process, and informal interviews with several students. The findings indicated that the students in this study valued peer reviews, but they were reluctant to write comments on peers’ drafts, especially at the beginning of the semester. However, toward the end of the semester, they felt more comfortable in providing written comments on peers’ drafts, particularly when they developed positive relationships with their peers. Suggestions for effective peer activity have also been provided.

기존의 재래식 유탕팽화유과의 문제점을 개선하기 위하여 진공을 이용한 진공팽화기를 설계 제작하였다. 공정변수에 따른 진공팽화유과의 특성을 비교 분석하기 위하여 부피팽화율, 밀도, 절단강도, 색도, 미세구조를 측정하였다. 진공팽화기의 공정변수는 가열온도(100, 120, 140, 160, 180oC), 예열시간(0, 2, 4, 6, 8분), 진공팽화시간(5, 10, 15, 20분)이며, 가열온도 100oC, 예열시간 6분, 진공팽화시간 10분에서 진공팽화유과의 부피팽화율은 10.04로 가장 높게 측정되었고, 밀도는 0.15 g/cm3로 가장 낮게 측정되었지만, 부피팽화율 9.47, 밀도 0.16 g/cm3으로 측정된 가열온도 120oC, 예열시간 4분, 진공팽화시간 5분에서의 진공팽화유과가 유탕유과의 외관 및 조직과 가장 유사하였다. 절단강도는 가열온도 100oC, 예열시간 6분, 진공팽화시간 15분에서 140 g/cm2로 가장 낮게 측정되었다. 색도는 예열시간과 진공팽화시간이 증가함에 따라 백색도가 증가하는 경향을 보였고, 황색도는 감소하는 경향을 보였으며, 적색도는 유의적 차이가 없었다. 진공팽화유과의 백색도(L값)가 유탕팽화유과보다 25정도 높았으며, 적색도(a값)와 황색도(b값)는 유의적 차이는 보이지 않았으며, 진공팽화유과의 미세구조는 가열온도 120oC, 예열시간 4분, 진공팽화시간 5분에서 기공이 작고 균일하였다. 유탕팽화유과와 비교 시 절단강도는 유사하였으나, 부피팽화율은 낮았고, 밀도는 높았다. 셀이 균일하게 형성된 진공팽화의 미세구조와는 달리 유탕팽화유과의 미세구조는 표면과 내부층의 차이가 확인되었다. 진공팽화기의 최적 공정조건은 진공팽화유과의 품질을 고려 할 때, 가열온도 120oC, 예열시간 4분, 진공팽화시간 5분으로 판단되었다.

The objectives of this study were the development of a synthesis technique for highly active nanosized ITO powder and the understanding of the reaction mechanisms of the ITO precursors. The precipitation and agglomeration phenomena in ITO and precursors are very sensitive to reaction temperature, pH, and coexisting ion species. Excessive ion and ions had a negative effect an synthesizing highly active powders. However, with a relevant stabilizing treatment the shape and size of ITO and precursors could be controlled and high density sintered products of ITO were obtained. By applying the reprecipitation process (or stabilization technique), highly active ITO and powders were synthesized. Sintering these powders at for 5 hours produced 97% dense ITO bodies.

Copper infiltration is demonstrated as a viable solution to achieve higher mechanical properties by filling the interconnected porosities of a ferrous structure with copper infiltrant. This paper will present the results of a design of experiments study based on the selected processing variables in the copper infiltration process. The variables are the following: Infiltrating temperatures, infiltrating time at pre-heat zone and hot zone, the green density of iron part, the migration of copper into the iron part at different processing conditions. The results show the flexibility of the infiltration process to attain certain mechanical properties by changing the processing conditions.

This paper uses a data mining methodologies to improve and predict cause of defect process variables in manufacturing process. Traditional statistical process control (SPC) techniques of control charting are not applicable in many process industries because it is difficult to analyze the cause of many process variables. The paper suggests that data mining methodologies useful when sequence rule, SVM (classification) methods are find out cause of defect process variables and SVM (prediction) methods used to predict process variables in manufacturing process. Therefore, it is allowing improved control in manufacturing process.

With development of the database, there are too many data on process variables and the manufacturing process for the traditional statistical process control methods to identify the process variables related with assignable causes. Data mining is useful in

This paper uses a data mining methodologies to improve and predict cause of defect process variables in manufacturing process. Traditional statistical process control (SPC) techniques of control charting are not applicable in many process industries because it is difficult to analyze the cause of many process variables. The paper suggests that data mining methodologies useful when sequence rule, SVM (classification) methods are find out cause of defect process variables and SVM (prediction) methods used to predict process variables in manufacturing process. Therefore, it is allowing improved control in manufacturing process.

마그네트론 스퍼터로 알루미나 기판위에 SnO2박막을 증착하여 증착온도, rf 전력, 공정기체 중 산소분율(O2/Ar)등 공정변수에 따른 박막의 미세구조와 가스검지 특성을 조사하였다. 증착된 박막의 미세구조는 결정성이 없는 비정질 구조(A), 비정질 기지 중에 결정이 분산된 구조(A=P), 방향성이 거의 없는 다결정 구조(P), 미세 기둥구조(FC), 조대한 기둥구조(CC), 고밀도 특성을 보이는 섬유상 구조(Zone T)의 6가지로 분류되었다. 공정 중 산소를 첨가하지 않았을 때, 저온, 낮은 rf 전력에서 A 구조가, 저온, 높은 rf 전력에서 A+P 구조가, 고온, 높은 rf 전력에서 P 구조가 형성되었고, 산소 첨가 시는 낮은 rf 전력, 저온에서 FC 구조가, 낮은 rf 전력, 고온에서 CC 구조, 높은 rf 전력, 저온에서 Zone T 구조가 형성되었다. 위의 미세구조를 가진 박막들을 센서로 제작하여 200˚C, 300˚C, 400˚C에서 CO 가스에 대한 민감도를 측정한 결과200˚C에서는 감도가 나타나지 않으며, 300˚C, 400˚C에서는 FC 구조를 가진 센서가 다른 미세구조를 가진 센서에 비해 우수한 감도를 나타냈다. 이는 미세한 column 들로 이루어진 FC 구조의 높은 비표면적으로 인해 산소와 피검가스의 흡착이 많아지게 되고, 가스흡착에 의한 저항변화, 즉 감도가 높게 나타나는 것으로 판단된다.