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온도변화에 따른 알루미늄합금 용접부의 피로수명에 관한 연구
이동길,양승훈,김건호,정재강 朝鮮大學校 機械技術硏究所 2002 機械技術硏究 Vol.5 No.1
본 연구에서는 저온용기 등에 많이 사용되고 있는 알루미늄 합금 A15083-0재에 대한 보호가스 혼합비율과 피로수명과의 관계를 규명하고자 혼합가스 비율을 여러 가지로 달리하여 GMA 용접을 실시하였다. 시험온도는 상온에서 극저온까지 단계적으로 낮추어가며 실시하였다. 용접재의 피로수명은 모든 불활성가스 혼합비율 및 노치 가공위치에서 모재보다 높은 피로수명을 보였으며, 영향부, 용융선 및 용착금속부 순으로 피로수명이 증가하였다. 상온에서부터 -85℃까지는 온도가 낮아짐에 따라 피로수명은 모재 및 Ar33%+He67%의 경우 증가한 반면, 다른 불황성 가스혼합비에서는 감소하는 경향을 나타내었며, -196℃ 극저온에서는 피로수명 크게 증가하여 저온재료로서 유용한 성질이 나타났다. The influence of mixing shield gas ratio and test temperature on fatigue life of welding zone were examined experimentally for a AI5083-O aluminum alloy. The GMA(Gas Metal Arc) welding was carried out for weld specimen with various mixing gas ratio(Ar100% + He0%, Ar67%+He33%, Ar50%+He50%, and Ar33%+He67%). The tested temperature range was from room temperature(+25℃) to cryogenic temperature(-192℃). The welding zone was divided into four sub-zones for analysis ; weld metal, fusion line, HAZ, and base metal. In the influence of mixing gas ration, fatigue life of weld metal was decreased with higher Argon gas ration, but fusion line and HAZ specimens were not influenced greatly, The fatigue life increased at lower temperatures, particularly at -196℃. It was known availability that the A15083-O is appropriate for used low temperature material.
공작기계의 선형경로에 대한 오차모델을 이용한 제어기 설계
길형균,이건복 한국공작기계학회 2004 한국공작기계학회 춘계학술대회논문집 Vol.2004 No.-
The work presented here deals with controller desgn using error model constructed with proportional control ramp response. The design aims at the improvement of transient response, steady-state error reduction with stability presrvation, generation of the consistent contour error through the proportional gain regulation of a mismatched system. The first step is to generate tracking-error curve with proportional control only and decide the added error signal shape on the error curve. The next is to construct a table for the steady-state loop gain with step input. The table is used for selecting the proportional gain. The effectiveness of the proposed controller is confirmed through the simulation and experiment.
秋健二,李鍾吉 仁荷大學校 스포츠科學硏究所 1991 論文集 Vol.3 No.-
This study is to find out influence on the physical fitness by reducing body weight. The 24 subjects selected were Judo players attending Pyung Taek Boy's High School. The processes of degree about reducing body weight are 2%, 2.5%, 2.9%, 3.3%, 4.2%, of one's normal body weight. The method used was to reduce and increas the exorcises. The objects used for physical fitness test tore gripping power, pull-ups, vertical jump, 1,000m running, sit-ups and flexibility of waist. The influences on the physical fitness by gradual degree of reducing body weight were as follows. 1) The record of gripping power went down when one reduced his weight by 2.5% . 2) The record of pull-ups went up when one reduced his weight by 2% and 2.5%, and went down when one reduced his weight by 3.3%. 3) The record of vertical jump went up when one reduced his weight by 2%, and went down hen one reduced by 2.9% 4) The record if 100m running showed no difference until one reduced his weight by 4.2% 5) The record of 1,OOOm running went down when one reduced his weight by 2.5% . 6) The record of sit- ups went down when one reduced ruts weight by 2.9% . 7) The record of waist flexibility went up when one reduced his weight from 2.5% to 4.2%.
정재강,김건호,이동길 조선대학교 생산기술연구소 1995 生産技術硏究 Vol.17 No.2
For the purpose of the prevention of fatigue fracture in the carbon steel forging materials which are used in the marine propeller shaft, this paper was analyzed behavior, rate and life of fatigue crack propagation, and was performed fatigue test in order to investigate date. The results are as follows: Smaller the grain size and larger the pearlite rate increases the fatigue strength was increased. Initial time of fatigue crack was lag and fatigue life was long due to increase in fatigue strength. Fatigue crack propagation life from initiation of slip band to growth of small crack, 2α= 1.30㎜, was occupied the most of fatigue crack propagation life. Fatigue crack propagation rate was able to express by d(2α)/dN = B2α/N_(f) because of the possibility of differentiation in the relation between fatigue crack length and cycle ratio. Fatigue crack propagation rate was able to express by d(2α)/dN = Cδ_(α)^(m)(2α)^(m) and this equation was the possibility of application of fatigue crack propagation life prediction in the experimental materials.
이석건 ( Lee Suk Gun ),이종원 ( Lee Jong Won ),이현우 ( Lee Hyun Woo ),김길동 ( Kim Gil Dong ) 한국농공학회 2000 한국농공학회 학술대회초록집 Vol.2000 No.-
Objects of this study were to find the cooling effect of solar-heated greenhouse with rock bed storage in summer season and to suggest operation method of cooling energy saving in summer cropping greenhouse. Experiments were performed to analyze inside environment variation of solar-heated greenhouse. When we took account of different shading and ground conditions of greenhouse, we could conclude that inside average daytime temperature of the solar-heated greenhouse was 2.0∼2.4℃ lower than the general greenhouse in summer season.
이석건 ( Lee Suk Gun ),이종원 ( Lee Jong Won ),이현우 ( Lee Hyun Woo ),김길동 ( Kim Gil Dong ) 한국농공학회 1999 한국농공학회 학술대회초록집 Vol.1999 No.-
This study were performed to find the cooling effect and to provide design data during summer season for the Pad & Fan system of greenhouse. The temperature variation along the greenhouse width were analyzed. Also, the effect of the pad location and fan capacity on the cooling of the greenhouse were analyzed. While Pad & Fan systems were operating, the temperatures in greenhouse were very different along the measuring locations. It is recommended that PAD location and FAN capacity should be considered to design the Fan and Pad system in order to provide greenhouse the optimum temperature condition.