SLS 3D 프린터를 이용하여 제작된 PA2200의 단축 반복 인장하중에 따른 피로 특성에 관한 연구

박준수,정의철,최한솔,김미애,윤언경,김용대,원시태,이성희,Park, Jun-Soo,Jeong, Eui-Chul,Choi, Han-Sol,Kim, Mi-Ae,Yun, Eon-Gyeong,Kim, Yong-Dae,Won, Si-Tae,Lee, Sung-Hee 한국금형공학회 2020 한국금형공학회지 Vol.14 No.1

In this study, the fatigue behavior and fatigue life characteristics of PA2200 specimens fabricated by SLS 3D printer were studied. Fatigue tests were performed according to the standard specification (ASTM E468) and fatigue life curves were obtained. In order to perform the fatigue test, mechanical properties were measured according to the test speed of the simple tensile test, and the self-heating temperature of the specimen according to the test speed was measured using an infrared temperature measuring camera in consideration of heat generation due to plastic deformation. There was no significant difference within the set test speed range and the average self-heating temperature was measured at 38.5 ℃. The mechanical strength at the measured temperature showed a relatively small difference from the mechanical strength at room temperature. Fatigue test conditions were established through the preceding experiments, and the loading conditions below the tensile strength at room temperature 23 ℃ were set as the cyclic load. The maximum number of replicates was less than 100,000 cycles, and the fracture behavior of the specimens with the repeated loads showed the characteristics of Racheting. It was confirmed that SLS 3D printing PA2200 material could be applied to the Basquin's S-N diagram for the fatigue life curve of metal materials. SEM images of the fracture surface was obtained to analyze the relationship between the characteristics of the fracture surface and the number of repetitions until failure. Brittle fracture, crazing fracture, grain melting, and porous fracture surface were observed. It was shown that the larger the area of crazing damage, the longer the number of repetitions until fracture.

폴리머코어 게이트 크기 변화가 두께 방향 수축률에 미치는 영향에 대한 연구

최한솔,정의철,박준수,김미애,채보혜,김상윤,김용대,윤경환,이성희,Choi, Han-Sol,Jeong, Eui-Chul,Park, Jun-Soo,Kim, Mi-Ae,Chae, Bo-Hye,Kim, Sang-Yun,Kim, Yong-Dae,Yoon, Kyung-Hwan,Lee, Sung-Hee 한국금형공학회 2020 한국금형공학회지 Vol.14 No.1

In this study, the variation of the shrinkage in the thickness direction of the molded parts according to the gate size of the polymer core fabricated through the 3D printer using the SLS method was studied. The polymer cores are laser sintered and the powder material is nylon base PA2200. The polymer cores have lower heat transfer rate and rigidity than the metal core due to the characteristics of the material. Therefore, the injection molding test conditions are set to minimize the deformation of the core during the injection process. The resin used in the injection molding test is a PP material. The packing condition was set to 80, 90 and 100% of the maximum injection pressure for each gate size. The runner diameter used was ∅3mm, and the gates were fabricated in semicircle shapes with cross sections 1, 2, and 3 ㎟, respectively. Thickness measurement was performed for 10 points at 2.5 mm intervals from the point 2.5 mm away from the gate, and the shrinkage to thickness was measured for each point. The shrinkage rate according to the gate size tends to decrease as the cross-sectional area decreases as the maximum injection pressure increases. The average thickness shrinkage rate was close to 0% when the packing pressure was 90% for the gate area of 1mm2. When the holding pressure was set to 100%, the shrinkage was found to decrease by 3% from the standard dimension due to the over-packing phenomenon. Therefore, the smaller the gate, the more closely the molded dimensions can be molded due to the high pressure generation. It was confirmed that precise packing process control is necessary because over-packing phenomenon may occur.

근전도 신호기반 손목 움직임의 추정을 위한 다중 특징점 추출 기법 알고리즘

김서준(Seo-Jun Kim),정의철(Eui-Chul Jeong),이상민(Sang-Min Lee),송영록(Young-Rok Song) 대한전기학회 2012 전기학회논문지 Vol.61 No.5

In this paper, the multi feature extraction algorithm for estimation of wrist movements based on Electromyogram(EMG) is proposed. For the extraction of precise features from the EMG signals, the difference absolute mean value(DAMV), the mean absolute value(MAV), the root mean square(RMS) and the difference absolute standard deviation value(DASDV) to consider amplitude characteristic of EMG signals are used. We figure out a more accurate feature-set by combination of two features out of these, because of multi feature extraction algorithm is more precise than single feature method. Also, for the motion classification based on EMG, the linear discriminant analysis(LDA), the quadratic discriminant analysis(QDA) and k-nearest neighbor(k-NN) are used. We implemented a test targeting twenty adult male to identify the accuracy of EMG pattern classification of wrist movements such as up, down, right, left and rest. As a result of our study, the LDA, QDA and k-NN classification method using feature-set with MAV and DASDV showed respectively 87.59%, 89.06%, 91.75% accuracy.

Shybot: 친밀도에 따라 애착을 형성하는 로봇

조연준(Yun Jun Cho),정의철(Eui Chul Jung) 한국HCI학회 2022 한국HCI학회 학술대회 Vol.2022 No.2

다양한 가정용 로봇이 등장하고 있는 요즘 사용자가 본인의 집에서 로봇과 함께 생활하는 데 있어 로봇과 애착을 형성할 수 있다면 보다 긍정적인 사용 경험을 얻을 수 있을 것이다. Shybot 은 타인과 주인의 얼굴을 구분하고 교류한 시간에 따라 자신을 드러내는 정도를 달리하여 친밀함을 나타내는 로봇이며, 주인의 애착 형성에 도움이 되는지에 대한 가능성을 탐색하고자 진행한 인터랙션 디자인이다.

소재와 문양분석을 통한 사이버쇼핑몰의 전통문화상품 디자인 특성 고찰

신준용 ( Shin Jun Yong ),박영순 ( Park Young Soon ),정의철 ( Jung Eui-chul ) 한국디자인트렌드학회 2011 한국디자인포럼 Vol.31 No.-

본 연구는 구매자가 상품을 구매하는데 있어 가장 대중적이고 일반적인 상품판매처인 사이버쇼핑몰을 대상으로 대표적인 전통문화상품의 현황을 파악하고 상품의 소재와 문양의 표현방식에 있어 전통문화상품의 디자인 특성분석을 목적으로 한다. 과거에는 장식위주의 상품과 목재, 섬유재, 지재, 금속재, 초재, 석재, 토재에 이르는 다양한 소재들이 활용되었다면 현재의 상품들은 온라인의 특성상 휴대가 용이하고 트렌드 반영이 쉬운 실용적 상품위주로 변화되었는데 소재와 문양표현이 한정된 상품들이 주종을 이룬다. 사이버쇼핑몰의 특성상 구매자가 선호하는 검증된 상품들에 한해서는 구색을 갖출 필요성이 있으므로 다변화·다양화를 위해 전통소재와 전통문양을 분석·응용한 현대적인 디자인 시도가 이뤄져야 한다. 특히, 소프트한 구조재를 가진 상품과 패션악세사리, 사이즈가 작은 상품의 경우는 트렌드를 적용한 상품개발이 용이한 품목이므로 시대적 요구를 바로 구현하는 사이버쇼핑몰의 특성을 이용하여 실용적· 감각적인 전통 상품군을 개발, 발전시켜야 한다. This study aims to describe how classes of traditional cultural goods have changed over the last ten years and to analyze the design characteristics of those goods, especially based upon the data collected from the online shopping malls because they are the most popular and common shopping attractions for purchasers. A study conducted in 2001 had focused on decoration products traded in offline markets and varied in raw materials: wood, textile, paper, metal, grass, and soil. On the contrary, this paper is dedicated to commodities which, as traded online, become to have portable and practical characteristics reflecting the current fashion, and most of them turn out to be limited in materials and patterns. The comparison shows that a modern type of design should be attempted to satisfy the needs of differentiation and variation by analyzing and applying the traditional materials and patterns because online shopping malls need to provide assortment to customers with regard to goods preferred and selected with care. Specifically, the goods that are small-sized ones, fashion accessories, and products with soft materials need to be developed in the practical and sensual ways, because they are easy to be crafted to reflect the trends and the operational features of online shopping malls which are good at realizing the trends.

북청사자놀음의 벽사진경(辟邪進慶)을 재구성한 인터랙션 디자인

김민준(Min-Jun Kim),정의철(Eui-Chul Jung) 한국HCI학회 2022 한국HCI학회 학술대회 Vol.2022 No.2

우리나라의 문화적 위상이 높아지는 가운데 예술과 디자인 분야에서 전통의 요소를 기반으로한 시도의 필요성을 느꼈다. 이에 따라 우리나라의 대표적 민속놀이 중 하나인 북청사자놀음을 재구성하고자 하였다. 북청사자놀음의 가장 주된 목적인 벽사진경(辟邪進慶)(나쁜 기운을 내쫓고, 좋은 기운을 불러옴)을 전시공간에 재구성하여 관람객들에게 최근 코로나19로 인한 펜데믹의 악재를 물리치고 길운을 불러온다는 의미를 전달하고자 의도하였다.

오픈 시스템을 적용한 프로젝트 아이덴티티 프로그램의 개발 - 멸종위기종 복원사업의 사례를 중심으로

이현주 ( Lee Hyunju ),박영순 ( Park Youngsoon ),정의철 ( Jun Eui-chul ),이성식 ( Lee Sungsik ),이지현 ( Lee Jeehyun ),주혜영 ( Chu Hyeyoung ),김소연 ( Kim Soyoun ),박영진 ( Park Youngjin ),홍자경 ( Hong Jakyung ) 한국디자인트렌드학회 2009 한국디자인포럼 Vol.23 No.-

최근 들어 환경에 대한 온 인류의 관심과 중요성이 증가됨에 따라 환경보존과 관련된 많은 프로젝트가 진행되고 그에 따라 많은 디자인 결과물들이 제시되고 있다. 그러나 많은 프로젝트들이 단발성으로 끝남으로 인해서 경제적인 측면에서도 많은 손실을 주는 경우가 있다. 환경부의 멸종위기종 복원사업은 멸종위기종의 대상이 계속적으로 바뀌면서도 일관성 있는 프로젝트의 고지와 범국민적 의식의 전환이 필요한 장기 프로젝트이다. 이 같은 프로젝트의 경우, 단발성으로 끝나는 기존의 아이덴티티 프로그램보다는 상황에 맞추어 계속 적용 가능한 열린 구조의 프로젝트 아이덴티티의 프로그램이 절실히 필요하다고 보았다. 본 연구는 멸종위기종 복원사업을 사례로 대국민 커뮤니케이션의 툴로써 효과적인 프로젝트 아이덴티티의 방향 및 실제 적용 방안을 제안하였다. With the recent increase in mankind`s interest in the importance of the environment, many projects related to environmental preservation are being implemented and numerous design results from these projects are being presented. But many projects terminate as a one-time event and, even in economic terms, often lead to losses. In the case of endangered species restoration project, which require continued persistence and nationwide transformation of people`s awareness, there is a need to move away from a simple identity program that ends as a one-time event and to develop a project identity program based on an open system concept allowing continuous application of the system tailored to given situations. Based on examples of endangered species restoration projects, this study presents the direction and the plan for actual application of an effective project identity as a public communications tool.

간 피막하 혈종을 동반한 독사교상 1예

최상경(Sang Kyung Choi),박순태(Soon Tae Park),하우송(Woo Song Ha),홍순찬(Soon Chan Hong),한호성(Ho Seong Han),황병권(Byoung Kwon Hwang),장종연(Jong Yeon Jang),정의철(Eui Chul Jung),이영준(Young Jun Lee) 대한외과학회 1991 Annals of Surgical Treatment and Research Vol.40 No.2