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3D 프린터 출력물의 적층 두께에 따른 초음파 속도 상관관계 연구
최선호(Sunho Choi),박준필(Junpil Park),이재선(Jaesun Lee) 한국비파괴검사학회 2021 한국비파괴검사학회지 Vol.41 No.2
3D 프린터는 소재를 겹겹이 쌓아 올려 적층하는 방식으로 기존의 공작기계와 같은 절삭 방식 대비 저렴한 비용과 시간으로 정교하고 복잡한 제품을 생산할 수 있다. 3D 프린터의 발전으로 생산 제조 방식에 새로운 패러다임을 제시했으나 적층 제조품에 대한 신뢰성 평가 방법과 기준이 명확하지 않다. 본 논문에서는 SLA(Stereo Lithography Apparatus) 방식을 이용하여 ABS Resin 소재로 적층 두께 및 적층 조건에 따른 초음파 전파 특성 평가를 위한 시험편을 제작하였다. 이를 바탕으로 크기가 다른 임의의 결함을 추가한 결함 시편을 제작하여 3D 프린터 출력물에 초음파 기법을 이용한 비파괴 평가와 적층 조건에 따른 상관 관계에 대해 연구하였다. 적층 두께 1 ~ 4 mm 까지는 초음파 전파 시간이 급격하게 변화하는 것을 확인하였으며, 적층두께 6mm 초과 영역에서는 초음파 전파 속도가 오차범위로 수렴하는 것을 확인할 수 있다. 이러한 결과를 바탕으로 적층제조품의 상태 및 신뢰성 확보를 통해 산업현장으로 확대 적용할 수 있을 것이다. 3D printing is a method of stacking materials in layers, enabling the production of sophisticated and complex products at a lower cost while consuming a smaller amount of time compared to cutting methods such as those that employ conventional machine tools. The development of 3D printers has suggested a new paradigm for production and manufacturing methods; however, the method and criteria for structural diagnosis for additive manufacturing are unclear. In this study, a test piece for the evaluation of ultrasonic propagation characteristics according to the lamination thickness and lamination conditions was fabricated with ABS resin using the stereolithography apparatus (SLA) method. Based on this, a defect specimen was prepared with additional defects of different sizes; non-destructive evaluation of the 3D printer output was performed using an ultrasonic technique, and its correlation with the stacking conditions was studied. It was confirmed that the ultrasonic propagation time rapidly changes up to a stacking thickness of 1 to 4 mm, and it can be seen that the ultrasonic propagation speed converges to an error range in the region where stacking thickness exceeds 6 mm. Based on these results, it will be possible to expand the application of 3D printing to industrial sites by securing the state and reliability of the laminated product.
최선호(Sunho Choi),이재선(Jaesun Lee),박준필(Junpil Park) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.05
With the development of 3D printing technology, various products are produced and used in industrial sites. While 3D printers have the advantage of complex shape production, there are still many points to be improved in terms of strength and quality. The nondestructively material properties measurements technology using ultrasonic waves has been applied in various ways to metallic and non-metallic materials. However, studies conducted on 3D printing products are insufficient, and studies on changes in material properties according to additive manufacturing conditions are also relatively insufficient. In this study, the state of the material according to the additive manufacturing conditions was measured in a non-destructive method using ultrasonic waves, and the correlation between the state of the material and the ultrasonic properties was studied. It was confirmed that the characteristics of ultrasonic waves change according to the lamination conditions, and based on these results, it is expected that the state and reliability of 3D printing products can be secured and applied to industrial sites.
최선호(Sunho Choi) 세계환단학회 2021 세계환단학회지 Vol.8 No.2
오늘날에는 홍익인간이라는 개념을 서구적이고 현대적인 사유체계 속에서 해석함에 따라, 홍익인간의 의미가 크게 왜곡되어 있다. 본 논문에서는 홍익인간이라는 개념이 만들어졌던 당시 우리의 고유한 사유체계를 통해 홍익인간의 개념을 해석해보았으며, 이에 따라 홍익인간의 올바른 의미가 ‘도道로써 널리 또 크게 중衆을 깨우쳐서, 사람과 사람 사이 삶의 도리를 실천하며 살아가게 하다, 또는 그렇게 살아가는 세상’으로 해석하고 있다. 이는 ‘깨우침’과 ‘공존 상생’을 강조하는 개념으로, 오늘날 우리가 일반적으로 이해하고 있는 홍익인간의 의미와는 크게 다름을 보여주고 있다, 즉 홍익인간이 ‘이타적인 사람의 모습’을 강조한, ‘널리 사람 또는 세상을 이롭게 하다’라는 의미가 아님을 강조하고 있다. 본 논문에서는 ‘고문헌에 기록된 한문 해석에 대한 접근법’과 ‘기존 역사연구방법에 대한 비판’을 통해, 홍익인간의 의미를 원래대로 복원하여 제대로 해석하기 위한 방법론을 제시하고 있다. 또한 ‘홍익弘益’은 ‘홍도익중弘道益衆’에서, ‘인간人間’은 ‘인재기간人在其間’에서 온 표현임을 보여주고 있다. 이를 통해 우리는 홍익인간이라는 개념이 삶에 대한 깊은 통찰력과 원대한 이상에서 나온 것임을 알 수 있다. In modern days, the Korean traditional concept of 'Hong-Ik-In-Gan' has been grossly misinterpreted and misunderstood, mainly due to the Westernized, modern way of life and thinking. In this article, we use the Korea's own traditional philosophy which dates back to approximately 9,000 years ago to reinterpret and restore the original concept of 'Hong-Ik-In-Gan'. The Korea's own traditional philosophy is unique and different from other Asian philosophies such as Confucianism, Taoism, Buddhism, etc. The origin of the Korea's own traditional philosophy can be traced back to two ancient Korean writings, Cheonbugyeong and Samilsingo, which have been passed on to today's Koreans for over 9,000 years. Cheonbugyeong and Samilsingo are very short, consisting of only 81 and 366 ideographic characters (known as Chinese characters today), respectively, but contain limitless implications to our lives and the universe well beyond imagination. The backbone of Korea's traditional philosophy laid down by Cheonbugyeong and Samilsingo has been further explained in detail in five old Korean books such as Samseong-gi I, Samseong-gi II, Dangun-Segi, Bukbuyeo-gi, and Taebaek-Ilsa, and these five old Korean books are put together in one book, known as Hwandan Gogi. According to the Korea's traditional philosophy, the meaning of 'Hong-Ik-In-Gan' is 'Enlighten (and/or brighten and/or civilize) the people by having them understand Do (道) so that they can live in accordance with Do(道), i.e., live together in mutual understanding and mutual prosperity‘. The meaning of Do(道) in the context of Korea's traditional philosophy is also different from other Asian philosophies in that it is very much scientific and practical. In such context, the concept of 'Hong-Ik-In-Gan' implies that no one can exist/live alone and that everyone needs everyone else. 'Hong-Ik-In-Gan' emphasizes 1) people should be enlightened (and/or brightened and/or civilized), and 2) they can only exist and should live together with mutual understanding and mutural prosperity. Unfortunately, the meaning of 'Hong-Ik-In-Gan' has been misinterpreted and misunderstood in modern days as one meaning 'Benefit and/or contribute to the wellbeing of other people so that all human beings can live together in peace and harmony'. That is, 'Hong-Ik-In-Gan' is misunderstood as a concept that emphasizes being altruistic as opposed to being selfish, which is the outcome of wrongly interpreting the unique Korean philosophical concept in a non-Korean philosophical context. Though most people praise being altruistic is more ethical and better to a society than being selfish, being altruistic is as troublesome as being selfish in that it is an unstable and incomplete concept as well. In this article, we also propose new methodology for interpreting the meaning of the ancient Korean writings in a more adequate way. We also show the origin of the expression, 'Hong-Ik-In-Gan'. In sum, we can say that the concept of 'Hong-Ik-In-Gan' truly reveals the deep insight and understanding about our life and the grandiose vision to our future.