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폐실리콘의 고에너지 밀링 과정에서 초기 입자 크기가 분말의 미세화에 미치는 효과
송준우,김효섭,김성신,구자명,홍순직,Song, Joon-Woo,Kim, Hyo-Seob,Kim, Sung-Shin,Koo, Jar-Myung,Hong, Soon-Jik 한국분말야금학회 2010 한국분말재료학회지 (KPMI) Vol.17 No.3
In this research, the optimal manufacturing conditions of fine Si powders from Si scrap were investigated as a function of different initial powder size using the high-energy ball milling equipment, which produces the fine powder by means of an ultra high-energy within a short duration. The morphological change of the powders according to the milling time was observed by Scanning electron microscopy (SEM). With the increasing milling time, the size of Si powder was decreased. In addition, more energy and stress for milling were required with the decreasing initial powder size. The refinement of Si scrap was rapidly carried out at 10min ball milling time. However, the refined powder started to agglomerate at 30 min milling time, while the powder size became uniform at 60 min milling time.
Beacon System과 Encoder를 이용한 Omniwheel 연마 로봇의 주행 제어
송준우,최병찬,김태언,스리지드,이장명,Song, Jun-Woo,Choi, Byeong-Chan,Kim, Tae-Eon,Sreenivasan, Sreejith Manalipadam,Lee, Jang-Myung 대한임베디드공학회 2017 대한임베디드공학회논문지 Vol.12 No.4
Utilizing the existing polishing robot prevents unrestricted change of direction, driving, and identification of driving pathway. To overcome this barrier, driving mechaism has been designed with Omniwheels with encoders and RSSI method of beacon system has been utilized to identify the driving path by position recognition. Due to the wheel characteristics, the Omniwheel mobile robot generates greater slip than the conventional mobile robot, which reduces its driving accuracy. Therefore, to improve the driving accuracy, the localization is conducted through the fusion of encoder and RSSI of beacon data to compensate for the errors caused by Dead Reckoning and inaccuracy of sensors. Finally, the localization accuracies of the proposed and conventional indoor localization method are compared to show effectiveness of the proposed driving control for a polishing robot.
기계적 합금화 공정에 의한 Fe가 코팅된 Mg 탈황 분말 제조 연구
송준우,천병선,홍순직,Song, Joon-Woo,Guillermo, Otaduy,Chun, Byong-Sun,Hong, Soon-Jik 한국분말야금학회 2012 한국분말재료학회지 (KPMI) Vol.19 No.3
In this research, the coating behavior of Mg and Fe desulfurization powder fabricated by low energy and conventional planetary mill equipment was investigated as a function of milling time, which produces uniform Fe coated powders due to milling energy. Since high energy ball milling results in breaking the Fe coated Mg powders into coarse particles, low energy ball milling was considered appropriate for this study, and can be implemented in desulfurization industry widely. XRD and FE-SEM analyses were carried out to investigate the microstructure and distribution of the coating material. The thickness of the Fe coating layer reaches a maximum of 14 ${\mu}m$ at 20 milling hours. The BCC structures of Fe particles are deformed due to the slip system of Fe coated Mg particles.
초고에너지 볼 밀링공정에 의한 (Hf-Ti-Ta-Zr-Nb)C 고엔트로피 카바이드 분말 제조 및 미세화 거동
송준우,한준희,김송이,석진우,김효섭 한국분말재료학회 2022 한국분말재료학회지 (KPMI) Vol.29 No.1
Recently, high-entropy carbides have attracted considerable attention owing to their excellent physical and chemical properties such as high hardness, fracture toughness, and conductivity. However, as an emerging class of novel materials, the synthesis methods, performance, and applications of high-entropy carbides have ample scope for further development. In this study, equiatomic (Hf-Ti-Ta-Zr-Nb)C high-entropy carbide powders have been prepared by an ultrahigh- energy ball-milling (UHEBM) process with different milling times (1, 5, 15, 30, and 60 min). Further, their refinement behavior and high-entropy synthesis potential have been investigated. With an increase in the milling time, the particle size rapidly reduces (under sub-micrometer size) and homogeneous mixing of the prepared powder is observed. The distortions in the crystal lattice, which occur as a result of the refinement process and the multicomponent effect, are found to improve the sintering, thereby notably enhancing the formation of a single-phase solid solution (high-entropy). Herein, we present a procedure for the bulk synthesis of highly pure, dense, and uniform FCC single-phase (Fm3m crystal structure) (Hf-Ti-Ta-Zr-Nb)C high-entropy carbide using a milling time of 60 min and a sintering temperature of 1,600oC.
고에너지 밀링공정을 이용한 조대 마그네슘 분말의 미세화 거동
송준우,김효섭,김홍물,김택수,홍순직,Song, Joon-Woo,Kim, Hyo-Seob,Kim, Hong-Moule,Kim, Taek-Soo,Hong, Soon-Jik 한국분말야금학회 2010 한국분말재료학회지 (KPMI) Vol.17 No.4
In this research, the refinement behavior of the coarse magnesium powders fabricated by gas atomization was investigated as a function of milling time using a short duration high-energy ball milling equipment, which produces fine powders by means of an ultra high-energy within a short duration. The microstructure, hardness, and formability of the powders were investigated as a function of milling time using X-ray diffraction, scanning electron microscopy, Vickers micro-hardness tester and magnetic pulsed compaction. The particle morphology of Mg powders changed from spherical particles of feed metals to irregular oval particles, then platetype particles, with increasing milling time. Due to having HCP structure, deformation occurs due to the existence of the easily breakable C-axis perpendicular to the base, resulting in producing plate-type powders. With increasing milling time, the particle size increased until 5 minutes, then decreased gradually reaching a uniform size of about 50 micrometer after 20 minutes. The relative density of the initial power was 98% before milling, and mechanically milled powder was 92~94% with increase milling time (1~5 min) then it increased to 99% after milling for 20 minutes because of the change in particle shapes.
허리 장착 기반의 IMU 센서를 이용한 3D 보행자 위치 추정 알고리즘 연구
송준우(Jun-Woo Song),류양(Yang Liu),양회성(Hoe-Sung Yang),이강복(Kang-Bok Lee),이장명(Jang-Myung Lee) 제어로봇시스템학회 2018 제어·로봇·시스템학회 논문지 Vol.24 No.5
This paper proposes a three-dimensional pedestrian position estimation algorithm using a waist-mounted Inertial Measurement Unit (IMU) sensor. A Pedestrian Dead Reckoning (PDR) system has been implemented using a single IMU sensor to locate a pedestrian who is carrying the PDR system on his waist in a building in which GPS signals are too weak to be utilized for localization. The position estimation system using IMU data suffers from degraded accuracy caused by the bias drift of gyroscope values. This approach adopts the quaternion to reduce the bias drift and obtain the precise Euler angles to localize the pedestrian in two-dimensional space with the step length estimation. To extend the localization into three-dimensional space to incorporate situations in which the pedestrian is ascending or descending the stairs, Zero-Velocity UpdaTe (ZUPT) scheme has been applied for processing gyroscope data from the IMU sensor. Real experiments have been performed to show the proposed algorithm’s effectiveness in both two- and three-dimensional spaces.