• Journal of Ocean Engineering and Technology
• /
• v.15 no.3
• /
• pp.100-106
• /
• 2001

In this study, CT specimens were prepared from Pressure Vessel Steel which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -10$0^{\circ}C$ and -12$0^{\circ}C$ and in the range of stress ratio of 0.05 and 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ${\Delta}K_{th}$ in the early stage of fatigue crack growth (Region I) and stress intensity factor range ${\Delta}K$ in the stable of fatigue crack growth (Region II) was increased in proportion to descent temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN $-{\Delta}K$ in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It was assumed that the fatigue crack growth rate da/dN in proportion to descending temperature in Region II and the cryogenic-brittleness greatly affect a material with decreasing temperature.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2002.11b
• /
• pp.58-58
• /
• 2002

This study was excuted to decide the physiological characteristics of Pleurotus Ferulae Lanzi. P. Ferulae Lanzi. was tested to select pertinent substract, temperature and pH range for the growth. Mycelial growth of P. Ferulae Lanzi. was mostly supported on MYPA among other tested synthetic or semi-synthetic media. The temperature range for pertinent mycelial growth was about 25~32$^{\circ}C$ and mostly stimulated at $25^{\circ}C$. And the pertinent pH range of MYPA was 5.0~6.0. The required carbon and nitrogen source for mycelial growth of P. Ferulae Lanzi. was tested. The mycelial growth was mostly stimulated by soluble starch at content. The carbon sources for pertinent mycelial growth was starch or maltose. And the nitrogen source for pertinent mycelial growth was yeast extract.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2002.11b
• /
• pp.59-59
• /
• 2002

This study was excuted to decide the physiological characteristics of Lentinus lepides. L. lepides was tested to select pertinent substract, temperature and pH range for the growth. Mycelial growth of Lentinus lepides was mostly supported on MYPA among other tested synthetic or semi-synthetic media. The temperature range for pertinent mycelial growth was about 22~32$^{\circ}C$ and mostly stimulated at $25^{\circ}C$. And the pertinent pH range of MYPA was 3.0~4.0. The required carbon and nitrogen source for mycelial growth of Lentinus lepides was tested. The mycelial growth was mostly stimulated by soluble starch at content. The carbon sources for pertinent mycelial growth was maltose. And the nitrogen source for pertinent mycelial growth was peptone.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2002.11b
• /
• pp.60-60
• /
• 2002

This study was excuted to decide the physiological characteristics of Fomers fomentarius. F. fomentarius was tested to select pertinent substract, temperature and pH range for the growth. Mycelial growth of F. fomentarius was mostly supported on MYPA among other tested synthetic or semi-synthetic media. The temperature range for pertinent mycelial growth was about 22~32$^{\circ}C$ and mostly stimulated at $25^{\circ}C$. And the pertinent pH range of MYPA was 5.0~6.0. The required carbon and nitrogen source for mycelial growth of F. fomentarius was tested. The mycelial growth was mostly stimulated by soluble starch at content. The carbon sources for pertinent mycelial growth was glucose or starch. And the nitrogen source for pertinent mycelial growth was yeast

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2002.11b
• /
• pp.61-61
• /
• 2002

This study was excuted to decide the physiological characteristics of Kuehneromyces mutabilis. K. mutabilis was tested to select pertinent substract, temperature and pH range for the growth. Mycelial growth of K. mutabilis was mostly supported on MYPA among other tested synthetic or semi-synthetic media. The temperature range for pertinent mycelial growth was about 25~32$^{\circ}C$ and mostly stimulated at $25^{\circ}C$. And the pertinent pH range of MYPA was 5.0~6.0. The required carbon and nitrogen source for mycelial growth of K. mutabilis was tested. The mycelial growth was mostly stimulated by soluble starch at content. The carbon sources for pertinent mycelial growth was mannose or glucose. And the nitrogen source for pertinent mycelial growth was yeast extract or peptone.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.6
• /
• pp.775-782
• /
• 2013

In this study, as a series of studies aimed at investigating the spatial randomness of fatigue crack growth for friction stir welded (FSWed) 7075-T651 aluminum alloy joints, the fatigue crack growth behavior of FSWed 7075-T651 aluminum alloy joints was investigated for LT orientation specimens. Fatigue crack growth tests were conducted under constant stress intensity factor range (SIFR) control for 5 specimens of the FSWed 7075-T651 aluminum alloy, including base metal (BM), heat affected zone (HAZ), and weld metal (WM) specimens. The mean fatigue crack growth rate of WM specimens was found to be the highest, whereas that of HAZ and WM specimens was the lowest. Furthermore, the variability of fatigue crack growth rate was found to be the highest in WM specimens and lowest in BM specimens.

• Proceedings of the KWS Conference
• /
• 2001.05a
• /
• pp.224-227
• /
• 2001

In this study, CT specimens were prepared hem ASTM SA516 which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -8$0^{\circ}C$, -l$0^{\circ}C$ and -l2$0^{\circ}C$ and in the range of stress ratio of 0.1, 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range $\Delta K_{th}$ in the early stage of fatigue crack growth ( Region I ) and stress intensity factor range $\Delta$K in the stable of fatigue crack growth ( Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN - $\Delta$K in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It assumed that the fatigue crack growth rate da/dN is rapid in proportion to descend temperature in Region H and the cryogenic-brittleness greatly affect a material with decreasing temperature.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2001.05a
• /
• pp.320-325
• /
• 2001

In this study, CT specimen were prepared from Pressure Vessel Steel which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -8$0^{\circ}C$, -10$0^{\circ}C$ and -12$0^{\circ}C$ and in the range of stress ratio of 0.05 and 0.3 by means of opening mode displacement. At the constant street ratio, the threshold stress intensity factor range ΔK$_{th}$ in the early stage of fatigue crack growth(Region I) and stress intensity factor range ΔK in the stable of fatigue crack growth(Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm do/dN -ΔK in RegionII, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It was assumed that the fatigue crack growth rate do/dN is rapid in proportion to descending temperature in Region IIand the cryogenic-brittleness greatly affect a material with decreasing temperature.e.greatly affect a material with decreasing temperature.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.8 no.3
• /
• pp.387-387
• /
• 1998

This paper reports on a thermodynamic analysis for the GaN thick film growth by vapor phaseepitaxy method. The thermodynamic calculation was performed using a chemical stoichiometric algorism. Thesimulation variables include the growth temperature in a range 400~1500 K, the gas ratios $(GaCl_3)/(GaCl_3+NH_3)$and $(N_2)/(GaCl_3+NH_3)$. The theoretical calculation predicts that the growth temperature of GaN be in thelower range of 450~750 K than the experimental results. The difference in the growth temperature betweenthe simulation and the experiments indicates that the vapor phase epitaxy of GaN is kinetically limited,presumably, due to the high activation energy of thin film growth.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.8 no.3
• /
• pp.388-395
• /
• 1998

This paper reports on a thermodynamic analysis for the GaN thick film growth by vapor phase epitaxy method. The thermodynamic calculation was performed using a chemical stoichiometric algorism. The simulation variables include the growth temperature in a range 400~1500 K, the gas ratios $(GaCl_3)/(GaCl_3+NH_3)$ and $(N_2)/(GaCl_3+NH_3)$. The theoretical calculation predicts that the growth temperature of GaN be in the lower range of 450~750 K than the experimental results. The difference in the growth temperature between the simulation and the experiments indicates that the vapor phase epitaxy of GaN is kinetically limited, presumably, due to the high activation energy of thin film growth.