Earticle

WAAM(Wire Arc Additive Manufacturing) has gained attention as an innovative technology in small-batch, multi-product production due to its advantages of low production costs, rapid build rates, and design flexibility. However, challenges such as relatively low geometric accuracy, surface finish defects, residual stresses, and distortion due to high heat input persist and require improvement. This study analyzes the influence of deposition path angles on deposition performance in the WAAM process. Experiments were conducted using stainless steel (STS309MoL) wire, known for its excellent heat resistance and corrosion resistance due to its relatively high ferrite content within the austenitic structure. To mitigate residual stresses and distortion caused by high heat input, the CMT(Cold Metal Transfer) process was employed for five layers of deposition. Five different deposition path angles were selected as process variables, and the impact of deposition path angles on deposition performance was evaluated based on experimental results.

In this paper, the angle of the magnet composed of two layers waas designated as a design variables, and an analysis model for the rotor of the 100kW permanent magnet synchronous motor was selected. Compared the length of the magnetic flux barrier that changes according to the angle of the magnet, the use of the magnet, and the distance between the magnets. Through finite element analysis, we presented an improved model by comparing the characteristics of average torque, torque ripple, cogging torque, and total harmonic distortion.

2009 초등학교 교육과정에 따라 2014년에 처음으로 출간된 교과서 ≪수학 4-2≫에서는 이 전 교육과정에 따른 교과서에서는 취급하지 않았던 오목다각형을 새롭게 취급하고 있다. 그 러나 본 논문에서는 오목다각형의 취급을 재고할 필요가 있음을 보이기 위해, 먼저 다각형에 관해 논의한 후에, 2009 초등학교 교육과정은 오목다각형의 취급을 허용하고 있는가와 오목 다각형의 취급에서 논리적 비약은 없는가의 두 관점에서 오목다각형 취급과 관련한 문제점 에 관하여 논의했다. 그리고 다음과 같은 이유에서 오목다각형을 취급하는 것을 재고할 필요 가 있다는 것을 결론으로 제시했다. 첫째, 오목다각형의 취급에 관한 공론화 과정이 없었다. 둘째, 2009 초등학교 교육과정에서 오목다각형의 취급을 정당화해 주는 근거를 찾을 수 없 다. 셋째, 오목다각형의 취급에 논리적 비약이 있다. 넷째, 오목다각형의 취급에서 일관성이 없다

Elementary textbook ≪Mathematics 4-2≫ first published in 2014 according to the 2009 elementary mathematics curriculum has been dealing with concave polygons which were not treated in elementary textbooks according to the previous curriculum. However, n the present paper, to show that there is a need to reconsider the handling of the concave polygons, after discussions about the polygon, problems in handling the concave polygons were discussed in next two viewpoints: Does 2009 elementary mathematics curriculum allow handling of the concave polygons? are there any logical leaps in handling of the concave polygon? And the following reasons to reconsider the handling of the concave polygons are presented as conclusions. First, there was no process of publicizing the handling of the concave polygon. Second, the evidences that will justify the handling of the concave polygon can not be found in 2009 elementary mathematics curriculum. Third, there are logical leaps in the handling of the concave polygons. Fourth, there is no consistency in handling the concave polygons.

This paper proposes a six-step operation strategy for direct self-control (DSC) method of interior permanent magnet synchronous motor (IPMSM) based on the torque angle. Conventional DSC methods for induction motors (IMs) have been studied for railway applications since these methods are suitable for controlling high-power traction drives and for extending voltage utilization through a six-step inverter operation. However, IPMSMs controlled via conventional DSC methods for IMs cannot be properly controlled through a six-step operation since the torque angle is not considered. In addition, synchronous frame rotation causes a phase error at high speeds owing to the time delay of digital controllers. This paper presents a torque angle compensation that improves the dynamic performance. The effectiveness of the proposed DSC method was verified through experimental results.

Building design significantly influences the quality of artificial and natural lighting, particularly with the growing trend of larger glass facades. This study utilized simulation tools to analyze the distribution of illuminance and luminance in indoor spaces using high-performance LED lamps with varying reflector angles. The results demonstrated that a 50-degree reflector angle led to increased shading and glare compared to a 20- degree angle. Based on these findings, the study concluded that a 20-degree reflector angle is more appropriate for achieving an optimal indoor lighting environment.

본 연구는 삼각형의 내각, 외각의 이등분선의 성질증명에 대하여 수학영재를 위한 증명 수업모델 개발 및적용에 관한 것이다. 수학영재들은 수학 개념적인 부분과 문제풀이에서 뛰어난 실력을 갖고 있지만 증명을 많이 경험하지 않았기에 증명과정에 대한 어려움을 분석하고 유추 사고과정 모델을 기초로 브레인스토밍이 이루어질 수 있도록 수업모델을 설계하였다. 이후 수업모델을 투입함으로써 다양한 방법의 증명이 이루어짐을확인하였으며, 이는 곧 증명의 성공유무가 수학적 내용지식(정보적 지식)보다는 수학적 사고 방법(방법적 지식)의 차이에서 기인한다는 것을 의미한다고 볼 수 있다. 또한, 수학영재들끼리 자유로운 논의를 통해 증명의타당성을 검증해주며 증명의 세부적인 과정을 이해하고다른 증명방법을 고찰해보는 의미 있는 수업이 진행됨을 확인하였다.

The purpose of this study is to develop and apply a proof instructional model for mathematically gifted students to prove the properties of the triangle’s inner and outer bisections. Mathematically gifted students have excellent skills in mathematical concepts and problem solving, but they have not experienced many proofs, so they designed a teaching model to analyze the difficulties of the proof process and brainstorm based on an analogy thinking process model. Afterwards, it was confirmed that various methods of proof were made by inputting the instructional model, which means that the success or failure of the proof is due to differences in mathematical thinking methods (methodological knowledge) rather than knowledge of mathematical content (information knowledge). Additionally, it was confirmed that a meaningful class was conducted to verify the validity of the proof through free discussions among mathematically gifted students, understand the detailed process of the proof, and consider other methods of proof.