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Double Step Sintering Behavior Of 316L Nanoparticle Dispersed Micro-Sphere Powder
Jeon, Byoungjun,Sohn, Seong Ho,Lee, Wonsik,Han, Chulwoong,Kim, Young Do,Choi, Hanshin Walter de Gruyter GmbH 2015 Archives of metallurgy and materials Vol.60 No.2
<B>Abstract</B><P>316L stainless steel is a well-established engineering material and lots of components are fabricated by either ingot metallurgy or powder metallurgy. From the viewpoints of material properties and process versatility, powder metallurgy has been widely applied in industries. Generally, stainless steel powders are prepared by atomization processes and powder characteristics, compaction ability, and sinterability are quite different according to the powder preparation process. In the present study, a nanoparticle dispersed micro-sphere powder is synthesized by pulse wire explosion of 316L stainless steel wire in order to facilitate compaction ability and sintering ability. Nanoparticles which are deposited on the surface of micro-powder are advantageous for a rigid die compaction while spherical micro-powder is not to be compacted. Additionally, double step sintering behavior is observed for the powder in the dilatometry of cylindrical compact body. Earlier shrinkage peak comes from the sintering of nanoparticle and later one results from the micro-powder sintering. Microstructure as well as phase composition of the sintered body is investigated.</P>
Fabrication of three-dimensional scan-to-print ear model for microtia reconstruction
Jeon, Byoungjun,Lee, Chiwon,Kim, Myungjoon,Choi, Tae Hyun,Kim, Sungwan,Kim, Sukwha Elsevier 2016 Journal of Surgical Research Vol.206 No.2
<P><B>Abstract</B></P> <P><B>Background</B></P> <P>Microtia is a congenital deformity of the external ear that occurs in 1 of every 5000 births. Microtia reconstruction using traditional two-dimensional templates does not provide highly detailed ear shapes. Here, we describe the feasibility of using a three-dimensional (3D) ear model as a reference.</P> <P><B>Materials and methods</B></P> <P>Seven children aged from 11 to 16 (6 grade III and 1 grade II microtia) were recruited from Seoul National University Children's Hospital, Korea. We generated 3D–computer-aided design models of each patient's ear by performing 3D laser scanning for a mirror-transformed cast of their normal ear. The 3D-printed ear model was used in microtia reconstruction surgery following the Nagata technique, and its shape was compared with the casted ear model.</P> <P><B>Results</B></P> <P>One patient experienced irritation caused by accidently pouring resin into the external auditory meatus, and another had minor skin necrosis; both complications were successfully treated. The average percentage differences of the superior, inferior, anterior, posterior, and lateral views between the casted and 3D-printed ear models were 1.17%, 1.48%, 1.64%, 1.80%, and 5.44%, respectively (average: 2.31%), where the difference between the casted ear models and traditional two-dimensional templates were 16.03% in average.</P> <P><B>Conclusions</B></P> <P>Our results show that simple microtia reconstruction can be performed using 3D ear models. The 3D-printed ear models of each patient were consistent and accurately represented the thickness, depth, and height of the normal ear. The availability of the 3D-printed ear model in the operating room reduced the amount of unnecessary work during surgery.</P>
김윤재,Min Hyuk Lim,Byoungjun Jeon,최동현,Haeri Lee,정애진,Min Jung Kim,Ji Won Park,Ja-Lok Ku,Seung-Yong Jeong,Sang-Kyu Ye,Youdan Kim,KIMSUNGWAN 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.1
Gravity is omnipresent for all objects on Earth. However, in an environment of different gravitational stress (e.g., microgravity or partial gravity), cells and organs show different biological responses. So, researchers have attempted to achieve micro- or partial gravity on Earth through various approaches, such as parabolic flight or free fall. However, the duration of such ground experiments is highly limited, making it very difficult to conduct time-consuming tasks, such as cell culture. Thus, a three-dimensional (3D) clinostat is utilized as an alternative for experiments on the International Space Station. It provides time-averaged simulated micro- and partial gravity by using mechanical frames with two rotating actuators. This study proposes novel control algorithms for simulating micro- and partial gravity and validates them by applying it to the control of a manufactured 3D clinostat. First, the novel algorithm for time-averaged simulated microgravity (taSMG) provided a more uniformly distributed gravity field by reducing two poles the gravity-concentrated areas. The taSMG with reduced poles provides isotropic gravitational patterns, from which it is possible to minimize the unnecessary effect due to nonuniformity of the gravity vector direction. Second, the other suggested novel algorithm for time-averaged simulated partial gravity (taSPG) controls the pole sizes asymmetrically to generate the intended size of partial gravity. The suggested algorithms are based on mathematical models rather than totally randomized motions. Therefore, the convergence of gravity values, in the rotating frame over time, can be analytically predicted with improved accuracy compared with previously reported algorithms. The developed 3D clinostat hardware and algorithms will effectively provide well-validated taSMG and taSPG for cell growth experiments in future studies for space medicine.
A Study on the VR Goggle-based Vision System for Robotic Surgery
Young Gyun Kim,Gyeongbin Mun,Byoungjun Jeon,Jong Hyeon Lee,Dan Yoon,Byeong Soo Kim,Myungjoon Kim,Seong-Ho Kong,Kyu Eun Lee,Chang Wook Jeong,Minwoo Cho,Sungwan Kim 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.9
Robot-assisted surgery (RAS) using the da Vinci surgical system (dVSS) has been widely performed owing to its high-definition stereoscopic visualization and improved maneuverability, which has been developed from minimally invasive surgery. However, there was motivation to resolve the chronic fatigue suffered by surgeons because of stereo viewer, the vision system of the dVSS. Reflecting the clinical opinions, a virtual reality (VR) goggle was proposed to enhance the convenience by replacing the stereo viewer, and its applicability was investigated. Based on the da Vinci research kit, validation of the VR goggle was performed by analyzing the condition of its use and implementing the performance assessment. In addition, user evaluations, such as performance analysis, questionnaire surveys, and ergonomic analysis, were conducted to determine the difference in the performance and satisfaction between the stereo viewer and VR goggle. Following the IRB approval, a retrospective analysis of the results was performed. Based on the comparison between the vision systems, the VR goggle was evaluated positively by the surgeons and novices. Satisfaction with the ergonomic properties of the VR goggle averaged 3.9 on a five-point Likert scale, and there was no significant difference in the performance when using the VR goggle and stereo viewer in both groups. Adopting the VR goggle, the volume of the vision system could be decreased by 87.6%. Considering that the VR goggle was better than the stereo viewer in terms of satisfaction and ergonomic analysis with analogous performance, it has the main contribution that the VR goggle can be a promising candidate. as a new vision baseline to research the enhancements of the RAS platform in further studies.