In this study, based on the saturation magnetic flux density experimental values (Bs) of 622 Fe-based bulk metallic glasses (BMGs), regression models were applied to predict Bs using artificial neural networks (ANN), and prediction performance was evaluated. Model performance evaluation was investigated by using the F1 score together with the coefficient of determination (R2 score), which is mainly used in regression models. The coefficient of determination can be used as a performance indicator, since it shows the predicted results of the saturation magnetic flux density of full material datasets in a balanced way. However, the BMG alloy contains iron and requires a high saturation magnetic flux density to have excellent applicability as a soft magnetic material, and in this study F1 score was used as a performance indicator to better predict Bs above the threshold value of Bs (1.4 T). After obtaining two ANN models optimized for the R2 and F1 score conditions, respectively, their prediction performance was compared for the test data. As a case study to evaluate the prediction performance, new Fe-based BMG datasets that were not included in the training and test datasets were predicted using the two ANN models. The results showed that the model with an excellent F1 score achieved a more accurate prediction for a material with a high saturation magnetic flux density.

Hexagonal bolt, nut, fittings, and high-pressure valves with special alloy play an important role in many industrial products, for instance, such as semiconductor facilities, hydrogen stations and fuel cell electric vehicles. The purpose of this study is to predict the reaction force of roller in drawing system. Numerical analysis was conducted to obtain data for designing the turning wheel, which is key parts in drawing system, using the reaction force of roller. As the results, the reaction force of X axis direction was about 9~20 times larger than that of Z axis direction and the reaction force of Y axis direction was negligible. The maximum reaction force of roller was the case of 4 stage and the numerical results in this study could be helped for designing the mechanical parts of variable hexagonal rolling die.

To develop a high capacity lithium secondary battery, a new approach to anode material synthesis is required, capable of producing an anode that exceeds the energy density limit of a carbon-based anode. This research synthesized carbon nano silicon composites as an anode material for a secondary battery using the RF thermal plasma method, which is an ecofriendly dry synthesis method. Prior to material synthesis, a silicon raw material was mixed at 10, 20, 30, 40, and 50 wt% based on the carbon raw material in a powder form, and the temperature change inside the reaction field depending on the applied plasma power was calculated. Information about the materials in the synthesized carbon nano silicon composites were confirmed through XRD analysis, showing carbon (86.7~52.6 %), silicon (7.2~36.2 %), and silicon carbide (6.1~11.2 %). Through FE-SEM analysis, it was confirmed that the silicon bonded to carbon was distributed at sizes of 100 nm or less. The bonding shape of the silicon nano particles bonded to carbon was observed through TEM analysis. The initial electrochemical charging/ discharging test for the 40 wt% silicon mixture showed excellent electrical characteristics of 1,517 mAh/g (91.9 %) and an irreversible capacity of 133 mAh/g (8.1 %).

The Ag/WC electrical contacts were prepared via powder metallurgy using 60 wt% Ag, 40 wt% WC, and small amounts of Co3O4 with varying WC particle sizes. After the fabrication of the contact materials, microstructure observations confirmed that WC-1 had an average grain size (AGS) of 0.27 μm, and WC-2 had an AGS of 0.35 μm. The Ag matrix in WC-1 formed fine grains, whereas a significantly larger and continuous growth of the Ag matrix was observed in WC-2. This indicates the different flow behaviors of liquid Ag during the sintering process owing to the different WC sizes. The electrical conductivities of WC-1 and WC-2 were 47.8% and 60.4%, respectively, and had a significant influence on the Ag matrix. In particular, WC-2 exhibited extremely high electrical conductivity owing to its large and continuous Ag-grain matrix. The yield strengths of WC-1 and WC-2 after compression tests were 349.9 MPa and 280.7 MPa, respectively. The high yield strength of WC-1 can be attributed to the Hall–Petch effect, whereas the low yield strength of WC-2 can be explained by the high fraction of high-angle boundaries (HAB) between the WC grains. Furthermore, the relationships between the microstructure, electrical/mechanical properties, and deformation mechanisms were evaluated.

본 논문은 2022학년도 교양 음악 과목의 현황 및 성격을 파악하기 위하여 서울 소재 12개 대 학교를 선정하여 개설 현황과 강의개요의 내용을 분석하였다. 개설 현황 분석에 있어서는 개설 과목의 수와 주제를 분석했으며, 특히 자료가 일반인에게 공개되어 있는 10개 대학의 경우에는 2008학년도 자료와 비교하여 시대적 추이를 가늠하고자 했다. 개설 과목이 현저히 증가한 대학의 경우에는 교양교육을 전담하는 기관 또는 주체가 뚜렷함을 보여 주었으며, 개설 과목의 성격 역시 담당 기관 및 주체의 운영 방식과 직접적인 연관이 있음을 알 수 있었다. 교양 음악 과목의 주제 를 분석한 결과, 서양음악이 거의 절반을 차지하는 반면, 한국음악, 대중음악, 융복합의 순서로 그 나머지를 구성하며 세계음악은 미미한 것으로 나타났다. 슐러의 ‘독립적 음악 능력’에 기초하여 과목의 성격을 분류한 결과는 현재 이론적인 측면이 76%를 차지함으로써 연주와 창조의 측면이 부족한 것으로 분석되었다. 한편, 강의 개요의 내용을 요르겐슨의 다섯 가지 음악 교육철학에 기 초하여 질적연구 소프트웨어 엔비보로 코딩 분석하였다. 이때, 강의의 성격 및 강의개요서 서술방 식에 따라 분석 결과가 상이하게 나타날 수 있으며, 실질적인 강의의 내용과 동일하지 않을 수 있 음을 한계로 밝힌다. 연구의 결과, 지식과 가치, 특히 음악적 지식과 가치를 가장 중요하게 다루 고 있으며, 다음으로 실기 능력의 전수, 개인의 경험과 표현의 증대, 사회적 기여, 다양한 문화의 유지의 순서로 중요하게 여기는 것으로 나타났다.

목적 : 최근 전자기기의 발달로 인해 근거리 작업이 증가하고 있으며, 이로 인해 안 건강에 대한 우려가 증가함 에 따라 청광 차단에 대한 관심이 증가하고 있다. 방법 : 유해 광선 차단이 가능한 기능성 콘택트렌즈 소재 개발을 위해 reactive yellow 86을 안료 중합체에, 그리고 propyl gallate를 실리콘 하이드로겔 소재에 첨가제로 각각 사용하여 안 의료용 소프트 콘택트렌즈 제조에 적용하였다. 결과 : propyl gallate의 첨가량에 따라 접촉각이 68.25~42.50˚로 측정되었으며, 습윤성이 향상되는 것으로 나타났다. 또한, 제조된 컬러 소프트 콘택트렌즈는 산소투과성 및 습윤성이 우수함과 동시에 자외선 및 청광 차단 효과를 나타내었다. 결론 : reactive yellow 86 및 propyl gallate가 적용된 컬러 콘택트렌즈의 재료의 경우, 기본적인 안 의료용 하이드로젤 렌즈의 물성을 만족시킴과 동시에 우수한 자외선 및 청광차단 효과를 가지는 것으로 판단된다.

Demand for research on the use of hydrogen, an eco-friendly fuel, is rapidly increasing in accordance with global environmental problems and IMO environmental regulations in the shipbuilding and marine industry. In the case of hydrogen, similar to liquefied natural gas, it has a characteristic that its volume decreases hundreds of times during phase transformation from gas to liquid, so it must be stored in a tank in the form of liquefied hydrogen for transport efficiency. The material of the liquid hydrogen tank is selected in consideration of mechanical properties and hydrogen embrittlement at cryogenic temperatures. In this study, welding research was conducted on STS316L material, which was most commonly used in the space industry. In this study, flux cored arc welding was performed under 4 welding conditions to derive the optimal welding conditions for STS316L material, and then mechanical properties of the welded part were compared and analyzed.

The bandgap characteristics of semiconductor materials are an important factor when utilizing semiconductor materials for various applications. In this study, based on data provided by AFLOW (Automatic-FLOW for Materials Discovery), the bandgap of a semiconductor material was predicted using only the material’s compositional features. The compositional features were generated using the python module of ‘Pymatgen’ and ‘Matminer’. Pearson’s correlation coefficients (PCC) between the compositional features were calculated and those with a correlation coefficient value larger than 0.95 were removed in order to avoid overfitting. The bandgap prediction performance was compared using the metrics of R2 score and root-mean-squared error. By predicting the bandgap with randomforest and xgboost as representatives of the ensemble algorithm, it was found that xgboost gave better results after cross-validation and hyper-parameter tuning. To investigate the effect of compositional feature selection on the bandgap prediction of the machine learning model, the prediction performance was studied according to the number of features based on feature importance methods. It was found that there were no significant changes in prediction performance beyond the appropriate feature. Furthermore, artificial neural networks were employed to compare the prediction performance by adjusting the number of features guided by the PCC values, resulting in the best R2 score of 0.811. By comparing and analyzing the bandgap distribution and prediction performance according to the material group containing specific elements (F, N, Yb, Eu, Zn, B, Si, Ge, Fe Al), various information for material design was obtained.

운남 소수민족 소재 영화는 중국 영화 발전의 가장 중요한 부분 중 하나이며 중 국 영화계에서 큰 주목을 받았다. 운남에는 소수민족이 많고, 소수민족 지역은 독특 한 심미적 특징과 문화적 의미를 가지고 있기 때문에 중국 영화 발전에서 있어 가장 독특한 가치와 의미를 가진 민족적 기호가 되었다. 운남 소수민족은 중국 소수민족 문화의 보호와 전파에 중요한 의미가 있을 뿐만 아니라 운남 소수민족 소재 영화의 독특한 문화적 속성과 정치적 속성은 국가의 안정과 민족의 단결을 유지하는 등 중 요한 이데올로기적 역할을 발휘하고 있다. 그러나 중국의 영화 발전 배경에서 운남 소수민족 소재 영화의 발전은 여전히 더딘 속도로 발전하고 있다. 치열한 중국 영화 시장의 경쟁 속에서 운남 소수민족 문화의 가치와 매력을 발굴하고 현재의 영화 상 업화과 적절하게 융합하는 것은 매우 중요한 과제가 되었다. 따라서 본문은 개혁개 방 후 운남 소수민족 소재 영화의 발전 양상을 정리하고 발전 과정에 존재하는 문제 점을 분석함으로써 미래 발전 방향을 모색한다.

We attempted to provide an overview of the laws and current state of the 3D printing industry in South Korea and around the world, using the annual industry surveys and the Wohler report. Additionally, we reviewed articles relating to the potential exposure to hazards associated with 3D printing using metal materials. In South Korea, there were 406 3D printing-related businesses, employing 2,365 workers, and the market size was estimated at 455.9 billion won in 2021. Globally, the average growth rate of the 3D printing industry market over the past 10 years was 27.4%, and the market size was estimated at $11.8 billion in 2019. The United States had the highest cumulative installation ratio of industrial 3D printers, followed by China, Japan, Germany, and South Korea. A total of 6,168 patents related to 3D printing were registered in the US between 2010 and 2019. Harmful factors during metal 3D printing was mainly evaluated in the powder bed fusion and direct energy deposition printing types, and there is a case of material extrusion type with metal additive filaments. The number, mass, size distribution, and chemical composition of particles were mainly evaluated. Particle concentration increases during the opening of the chamber or post-processing. However, operating the 3D printer in a ventilated chamber can reduce particle concentration to the background level. In order to have a safe and healthy environment for 3D printing, it is necessary to accumulate and apply knowledge through various studies.