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포스터 전시회 : 분사압력 변화에 따른 디젤-DME연료의 다단분사 특성에 관한연구
정연호 ( Yun Ho Jeong ),양지웅 ( Ji Woong Yang ),오충환 ( Chung Hwan Oh ),임옥택 ( Ock Taeck Lim ),정수진 ( Soo Jin Jeong ),오세두 ( Se Doo Oh ) 한국액체미립화학회 2013 한국액체미립화학회 학술강연회 논문집 Vol.2013 No.-
An investigation on spray characteristics of fuels which diesel and di-methyl ether(DME) with change of injection pressure used the multi-injection in constant volume combustion chamber(CVCC). Diesel was already used famous fuel which we could use. DME showed similar features with diesel like as cetane number, auto-ignition temperature. High cetane number of diesel and DME could make possible to compression ignition. DME showed different atomization from diesel due to evaporating pressures and boiling points. Experiments were carried out in CVCC equipped with Delphi solenoid 6-hole type injector and the spray characteristics of diesel and DME were tested the various pre and pilot injection. Terms of injections and a number of injections in multi-injection has been controlled. Experiments were performed in 2 types that 1500rpm , 2000rpm and under the condition of injection ranging from 100bar to 500bar. From the results of this experiment diesel showed longer spray penetration than DME. That result showed different of atomization speed DME and diesel. Result of high injection pressure condition showed similar spray characteristics diesel and DME. After this investigation, possibilities of the using the DME in fuel business would be expected.
다원계 Zr합금에서 Sn첨가가 미세조직과 부식특성에 미치는 영향
김종성,박상윤,이명호,정용환,정연호,Kim, Jong-Seong,Park, Sang-Yun,Lee, Myeong-Ho,Jeong, Yong-Hwan,Jeong, Yeon-Ho 한국재료학회 1999 한국재료학회지 Vol.9 No.10
ZrNbFeCu-xSn 합금을 진공 아크 용해법으로 제조하여 $360^{\circ}C$의 물, $400^{\circ}C$의 수증기 및 36$0^{\circ}C$의 70ppm LiOH 분위기에서 부식실험을 실시하였으며, 시편의 미세구조는 광학현미경, SEM 및 TEM으로 관찰하였다. 36$0^{\circ}C$에서 210일까지 부식 실험한 결과 대부분의 합금이 천이 전 영역에서의 부식거동을 보였다. $400^{\circ}C$ 경우, 초기에는$ 360^{\circ}C$에서의 부식거동과 비슷한 경향을 보였으나 80일 이후부터는 천이현상이 발생하여 부식속도가 급격히 증가하는 경향을 나타내었는데, Sn량이 많을수록 보다 빠른 시간에 천이현상이 발생했다. LiOH 용액에서는 전반적으로 $400^{\circ}C$에서 보다 더 늦은 시간에 천이현상이 발생했다. 석출물은 Zr(Fe,Cu)$_2$나Zr(Fe,Cu)$_3$로 추정되는 성분을 가지지만, Sn의 증가에 따라 석출물의 조성이나 크기는 거의 변화가 없는 것으로 관찰되었다.
400W, 200,000rpm 급 마이크로터빈용 회전체의 위험속도 해석
홍도관(Do-Kwan Hong),우병철(Byung-Chul Woo),정연호(Yeon-Ho Jeong),김종무(Jong-Moo Kim),조윤현(Yun-Hyun Cho) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
This paper introduces a rotor with shrink fit, its structural analysis and rotordynamic analysis by 3D FEA. First, electrical analysis is performed to develop the ultra high speed motor. The required performances of motor are 400W, 200,000rpm, 89% efficiency ultra speed motor. The rotor size is decided by electrical procedure. At second step, the stability of the rotor structure is evaluated in loading condition(220,000rpm, 210℃) by structural analysis. The final step, the critical speed of rotor is extracted by Campbell diagram. The operating speed should be smaller than critical speed and have enough separation margin. There is no separation margin because of the large size of winding end turn. The outer diameter of rotor is limited by electrical performance. Therefore, that problem is overcame by controlling the supported point of bearing. In future, The prototype will be manufactured and the simulation result will be verified by prototype test.