• Title/Summary/Keyword: M-G 변형

Search Result 187, Processing Time 0.028 seconds

The friction effects at high strain rates of materials under dynamic compression loads (동압축 하중을 받는 재료의 고변형도율에서의 마찰영향)

  • 김문생
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.11 no.3
    • /
    • pp.454-464
    • /
    • 1987

  • The objective of this research is to analyze and evaluate the dynamic flow curve of metals under impact loading at both high strain rate (.epsilon.=1/h dh/dt > 10$\^$3/m/s/m) and large strain (.epsilon.=In h/h$\_$0/ > 1.0). A test method for dynamic compression of metal disc is described. The velocity of the striker face and the force on the anvil are measured during the impact period. From these primitive data the axial stress, strain, and strain rate of the disc are obtained. The Strain rate is determined by the striker velocity divided by the specimen height. This gives a slightly increasing strain rate over most of the deformation period. Strain rates of 100 to 10,000 per second are achieved. Attainable final strains are 150%. A discussion of several problem areas is presented. The friction on the specimen surfaces, the determination of the frictional coefficient, the influence of the specimen geometry (h$\_$0//d$\_$0/ ratio) on the friction effect, the lock-up condition for a given configuration, the friction correction factor, and the evaluation of several lubricants are given. The flow function(stress verus strain) is dependent on the material condition(e.g., prior cold work), specimen geometry, strain rate, and temperature.

  • https://doi.org/10.22634/KSME.1987.11.3.454 인용 PDF

Dynamic deformation behavior of aluminum alloys under high strain rate compressive/tensile loading (상용 알루미늄 합금의 고속 인장/압축 변형거동 규명)

  • Lee, O.S.;Kim, G.H.;Kim, M.S.;Hwang, S.W.
    • Proceedings of the KSME Conference
    • /
    • 2000.11a
    • /
    • pp.268-273
    • /
    • 2000

  • Mechanical properties of the materials used for transportations and industrial machinery under high strain rate loading conditions are required to provide appropriate safety assessment to these mechanical structures. The Split Hopkinson Pressure Bar(SHPB) technique, a special experimental apparatus, can be used to obtain the material behavior under high strain rate loading condition. In this paper, dynamic deformation behaviors of the aluminum alloys, Al2024-T4, Al6061-T6 and Al7075-T6, under high strain rate compressive and tensile loading are determined using SHPB technique.

  • PDF

Effect of Modified Cyclone Dust Collector in Windowless Broiler Building (변형된 사이클론 먼지포집기의 이용이 무창계사의 먼지농도에 미치는 영향)

  • Choi, H.C.;Yeong, G.Y.;Song, J.I.;Kang, H.S.;Kwon, D.J.;Yoo, Y.H.;Yang, C.B.;Chun, S.S.;Kim, Y.K.
    • Journal of Animal Environmental Science
    • /
    • v.13 no.2
    • /
    • pp.97-104
    • /
    • 2007

  • This study was carried out to develop the modified cyclone dust collector in windowless broiler building measuring 12 m wide, 46 m long, with a side wall height of 3 m and a capacity of 12,800 birds. Ventilation rate in windowless broiler building was $0.014{\sim}0.015\;and\;0.158{\sim}0.181cmm$ in second weeks and fifth weeks of age, respectively. Ammonia concentration was $13{\sim}16\;and\;20{\sim}24\;ppm$ in first and second weeks of age, respectively. Amount of dust collected in dust collector each week was 104.1, 274.7 and 388.6g in first, second and third weeks of age. But it was decreased from fourth weeks of age because of the increased ventilation rate. Total suspended particulate(TSP) of polluted air was $3,111.7{\sim}8,745.2{\mu}g/m^3$, but it was decreased to $530.8{\sim}2,264.4{\mu}g/m^3$ when it passed through the dust collector. Collecting efficiency was $54.2{\sim}82.9%$ in TSP. But collecting efficiency of Particulate matter smaller than $1{\mu}g$ (PM1.0) was $7.6{\sim}33.8%$, and lower than TSP. TSP concentration in control broiler house was 1,387.6 and $4,210.1{\mu}g/m^3$ in first and fourth weeks of age, respectively. But it was decreased to 876.3 and $2,535.3{\mu}g/m^3$ in broiler house operated dust collector in first and fourth weeks of age, respectively. Dust collecting efficiency for TSP was $36.8{\sim}39.8%$, and it was decreased to $11.4{\sim}39.8%$ in smaller dust size.

  • PDF

Effects of Fermented Mulberry Leaves (Morus alba L.) on Oxidative Modification of Antioxidnat Enzymes (항산화 효소의 산화적 변형에 뽕잎 발효물이 미치는 영향)

  • Kang, Jung Hoon
    • Journal of the Korean Applied Science and Technology
    • /
    • v.36 no.3
    • /
    • pp.985-994
    • /
    • 2019

  • Muberry (Morus alba L.) leaves fermented with Hericium erinaceum mycelium (MA-HE) were assessed for the protection against oxidative modification of antioxidant enzymes, Cu,Zn-superoxide dismutase(SOD) and ceruloplasmin(CP). MA-HE were shown to significantly inhibited oxidative modifications and inactivations of Cu,Zn-SOD and CP induced by peroxyl radical. Antioxidant activity of MA-HE evaluated using peroxyl radical scavenging assays. MA-HE showed 44.03% of peroxyl radical scavenging activity at $100{\mu}g/mL$. Thus, MA-HE protect the antioxidant enzymes from oxidative damage by the scavenging peroxyl radicals. The results suggested that MA-HE was effectively removed reactive oxygen species in cells, thereby protecting cytotoxicity caused by oxidative stress.

  • https://doi.org/10.12925/jkocs.2019.36.3.985 인용 PDF KSCI

Investigation on the Heating Patterns Depending on the Packaging Materials During Microwave Cooking (포장 소재에 따른 전자레인지 가열 조리 패턴 조사)

  • Lee, Hwa Shin;Cho, Ah Reum;Moon, Sang Kwon;Yoon, Chan Suk;Lee, Keun Taik
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
    • /
    • v.21 no.1
    • /
    • pp.27-34
    • /
    • 2015

  • Heating patterns depending on the packaging materials were examined in order to investigate the causes of thermal deformation of packages used for ready-to-eat foods for microwave heating due to the non-uniformity of microwaves. Physical properties including tensile strength, heat-resistance and elongation of four different CPP grades were compared. High retortable CPP had higher sealing strength and heat resistance compared to the conventional CPPs. All CPP samples tested were proved to have melting temperatures around $160^{\circ}C$. However, they were all thermally deformed by microwave heating due to a limited penetration of microwave and non-uniform heating within the spicy sauce of high viscosity contained high salt, especially on the above the filling line and sealing edge of pouches. When the laminated stand-up pouches composed of G-PET/PET/PET/CPP and G-PET/PET/NY/CPP were retorted and microwaved, significant deformations were noticed in both samples after retorting. Besides, pouches contained titanium dioxide showed more intense thermal deformation than the control. When the $10{\mu}m$ aluminium foil was affixed on the pouch, small thermal deformation was observed only in the bottom layer. More studies are required to prevent the thermal deformation of packaging materials used for RTE foods during microwave heating by developing the technologies to increase the thermal stability of CPP layer and the modification of packaging design to modify the microwave access into the package.

  • PDF