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주병돈(Byeong-Don Joo),이성문(Sung-Mun Lee),손영명(Young-Myung Son),문영훈(Young-Hoon Moon) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Hydroforming technology draws attentions of automotive industries due to its advantages such as weight reduction, increased strength, improved quality and reduced tooling cost. Hydroformed automotive parts used as structural components in vehicle body frame often have to be structurally joined at some point. Therefore it is useful if the hydroformed automotive parts can be given a localized attachment flange. In this study, hydroforming process for the flanged tubular parts was proposed. Tube hydroforming experiments were conducted at various conditions. Forming characteristics at various pressure conditions were evaluated. With optimized condition flange was sucessfully formed. The results show that flanged automotive parts can be successfully produced with tube hydroforming.
주병돈(Byeong Don Joo),이혜경(Hyae Kyung Yi),장정환(Jeong Hwan Jang),권승오(Seung O Kwon),문영훈(Young Hoon Moon) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.6
Hydroforming is one of the useful processes in the automotive industry and recently for to improve the fuel efficiency, automotive industry focus on weight reduction. Aluminum alloys are light and has high structural rigidity, the need for hydroforming of aluminum alloy is increased. In this study, hydroformability and fracture criteria of FE analysis based on ductile fracture were investigated in warm hydro forming of Al 6061 tube and to evaluate the hydroformability, un i-axial tensile test and bulge test were performed at room temperature and 200℃. The measured flow stresses were used as input parameters for FE analysis, the damage values were calculated by FE analysis based on ductile fracture criteria at maximum radius of free bulged tubes, and damage values were compared of hexagonal shaped hydroformed parts.
전기-유압식 추력벡터제어 구동장치시스템의 합성공진 특성 연구
민병주(Byeong-Joo Min),최형돈(Hyung-Don Choi),강이석(E-Sok Kang) 한국항공우주연구원 2008 항공우주기술 Vol.7 No.1
본 논문에서는 발사체에 적용하는 전기-유압식 추력벡터제어 구동장치시스템의 합성공진 현상에 대한 해석 연구결과를 기술한다. 합성공진 현상은 위치서보 구동장치시스템을 유연한 발사체 기체구조체 지지부에 장착하였을 때 발생한다. 이는 관성부하를 갖는 전기유압식 위치서보 시스템의 유압공진 현상과 유연한 기체구조체 지지부의 구조공진 현상의 합성에 의하여 발생한다. 합성공진 현상은 발사체 제어시스템에 의하여 되먹임 및 증폭되어 안정성을 악화시킬 수 있다. 이와 같은 현상을 정확하게 예측 및 분석할 수 있는 비선형모델을 개발하였으며 이에 기반을 둔 합성공진 억제 특성이 우수한 동적 압력 되먹임 (dynamic pressure feedback) 제어기법을 개발하였다. In this paper, the analysis results of synthetic resonance characteristics are described for the electrohydraulic thrust vector control actuation system. The synthetic resonance is induced by integration of position servo actuation system on the flexible launch vehicle mounting structure. The new resonance mode is synthesized due to composition of hydraulic resonance for electrohydraulic position servo system with inertia load condition and structural resonance for flexible mounting structure. This synthetic resonance can make stability of control system worse by feedback and amplification of control system. The exact nonlinear analysis model of this phenomenon is developed to predict and design a control algorithm for improvement characteristics. The DPF(Dynamic Pressure Feedback) control algorithm has been designed and has excellent resonance suppression capability.
고체모터 가동노즐 추력벡터제어용 구동장치시스템의 제어특성 연구
민병주(Byeong-Joo Min),이희중(Hee-Joong Lee),박문수(Moon-Su Park),최형돈(Hyung-Don Choi) 한국항공우주학회 2005 韓國航空宇宙學會誌 Vol.33 No.1
가동노즐의 회전운동을 가능케 하는 플렉스실 베어링은 고정되어 있지 않은 회전중심과 고체모터의 연소압력에 의한 압축운동 등과 같은 고유의 비선형 운동특성을 갖는다. 이를 극복하고 발사체의 정확한 자세제어를 수행하기 위해서 플렉스실 베어링 장착 가동 노즐의 추력벡터제어용 구동장치시스템은 보상제어회로 구성을 위한 별도의 가동노즐 위치정보 궤환 센서인 카운터 포텐시오미터를 필요로 한다. 이를 반영한 고체모터 가동노즐 추력벡터제어용 구동장치시스템 시제품 및 시험평가장치, 보상제어회로에 대한 설계 및 제작, 시험이 수행되었다. 연계통합시험 결과를 바탕으로 플렉스실 베어링을 장착한 가동 노즐의 고유특성과 이의 추력벡터제어에 사용되는 구동장치시스템의 제어특성을 분석하였으며 그 결과를 본 논문에 요약하였다. The motion of flexseal bearing for movable nozzle has inherent nonlinear characteristics due to floating rotational center and compression by combustion pressure of solid motor. To perform precise attitude control in spite of these characteristics, the TVC actuation system requires counter potentiometer as an extra position feedback sensor of movable nozzle to form a compensated control loop. The prototype TVC actuation system, test equipments and compensated controller are newly designed, manufactured and tested in consideration of counter potentiometer. On the basis of integration test, the inherent characteristics of movable nozzle and control characteristics of its TVC actuation system are analyzed and summarized in this paper.
Whole genome sequence of acute hepatopancreatic necrosis (AHPND) isolated from Korea
Seong Don Hwang,Jee Youn Hwang,Byeong Chul Kang,Hae Ryeon Jeon,Won Joo Chun,Da won Lee,Sae bom Sohn,Su Mi Kim,Seok Ryel Kim,Kyoo Yeol Lee,Myung Hee Jung,Jung Soo Seo,Mun-Gyeong Kwon,Bo Young Jee 한국수산해양기술학회(구 한국어업기술학회) 2018 한국수산해양기술학회 학술발표대회 Vol.2018 No.11
Characterization of Deposited Layer Fabricated by Direct Laser Melting Process
장정환,Byeong Don Joo,Chester J. Van Tyne,문영훈 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.3
Deposition dimensions are important in the final applications of products made by direct laser melting (DLM). This investigation used a 200 W fiber laser to produce single-line beads from stainless steel 316L powder using a variety of different energy distributions. To investigate the deposited layer, deposition width, height, penetration depth, and side surface roughness were measured. In order to validate the effectiveness of the two main process parameters (laser power and scan rate), multi-layered beads were fabricated by the sequential layering of single lines. It was found that with an increase in linear energy density, the wetting angle was reduced, and the average roughness was also increased with linear energy density. An equation that predicts the deposition height for a multi-layered bead is proposed and experimentally validated in this study. For deposited layer applications, the material properties of the deposited layer, such as contact angle, interfacial contact resistance, and flexural strength are estimated. The rougher deposited layers show higher contact angle and interfacial contact resistance. The flexural strength of the DLM fabricated specimen is above 250 MPa.