• Journal of Animal Science and Technology
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• v.44 no.6
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• pp.661-668
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• 2002

This study was conducted to investigate the effect of environmental factor on milk yield and to estimate lactation curve in Korean cattle. The data for milk yields were collected from 118 cows from 1997 to 2000 at National Livestock Research Institute in Daekwanryoung, Kangwon-do. Average daily milk yields for 1st, 2nd, 3rd and 4th month after calving were 3.74kg, 3.64kg, 3.26kg and 2.99kg. Average daily milk yield for the four months was 3.52kg. The milk yields for cows calved in spring were larger than those calved in fall. Lactation curve of Korean cattle was $y_n$=$2.4845n^{0.1734}e^{－0.0060n}$. Peak milk yield was 3.75kg on 29.03 day after calving. The peak milk yields for multi-parous cows were larger than those of primiparous cows. The peak milk yields for multi-parous cows reached later than those for primiparous cows. The cows calved in spring had higher and earlier peak milk yields than those calved in fall had.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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• pp.1451-1459
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• 1995

The objective of this paper is to evaluate the material properties of SA312 TP316 and SA312 TP304 stainless steels and their associated welds manufactured for safety injection system of Yonggwang 3,4 nuclear generating stations. A total of 62 tensile tests and 46 fracture toughness tests were conducted and the effects of various parameters such as pipe size, crack plane orientation, tests were conducted and the effects of various parameters such as pipe size, crack plane orientation, test temperature, welding on material properties were discussed. Test results show that the effect of test temperature on fracture toughness was significant while the effects of pipe size and crack plane orientation on fracture toughness were negligible. Fracture toughness of the weld metal was in general higher than that of the base metal.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.853-854
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1175-1176
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• 2010

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1063-1066
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• 2006

We report the transparent getter performance of $POCl_3$ and amine based system by using the acid-base reaction in the fastest chemical reaction for top emitting OLEDs. OLED device including synthesized getter component exhibited stable current-voltage curve after 500 hours under $60^{\circ}C$, 90% RH storage condition and showed stable surface performance until 520 hours.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.24-24
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• 2003

We present preliminary results about the quasi-simultaneous near-infrared light curves of the long-period eclipsing polar V1309 Ori in the J, H, K', and K bands with almost complete orbital phase coverage using the CFHT-IR camera. The optical light curve in the V and R bands, obtained by 1.8m Telescope at BOAO, will be also presented. The shape and the amplitude of the orbital light curve change significantly from optical to near-infrared wavelengths.

• Transactions of Materials Processing
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• v.16 no.5 s.95
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• pp.348-353
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• 2007

The propagation of a macro-scale crack and the accompanying transformation zone around it was visualized in an Y-TZP ceramic using a mechano-luminescence (ML) technique. The technique allows realistic fractures that take place catastrophically in actual applications to be realistically stimulated. Unlike conventional quasi-static R-curves, the ML technique on a relatively fast time frame permitted a so-called quasi-dynamic R-curve in the crack speed range from 50 to 140 m/sec. to be measured. Effective toughening then commenced and the applied stress intensity factor increased to 27 $MPa{\sqrt{m}}$. The transformation zone height obtained from the ML observations was in good agreement with that predicted by the Marshall model, and coincided with previously observed results for quasi-static conditions by Raman spectorscopy and x-ray analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.729-732
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• 2003

The K-R design curve is an engineering method of linear-elastic fracture analysis under plane-stress loading conditions. By the way, linear-elastic fracture mechanics (LEFM) is valid only as long as nonlinear material deformation is confined to a small region surrounding the crack tip. Like general steels, it is virtually impossible to characterize the fracture behavior with LEFM, in many materials. Critical values of J contour integral or crack tip opening displacement (CTOD) give nearly size independent measures of fracture toughness, even for relatively large amounts of crack tip plasticity. Furthermore, the crack tip opening displacement is the only parameter that can be directly measured in the fracture test. On the other. the crack tip opening angle (CTOA) test is similar to CTOD experimentally. Moreover, the test is easier to measure the fracture toughness than other method. The shape of the CTOA curve depends on material fracture behavior and, on the opening configuration of the cracked structure. CTOA parameter describes crack tip conditions in elastic-plastic materials, and it can be used as a fracture criterion effectively. In this paper, CTOA test is performed for steel JS-SS400 hot-rolled thin plates under plane-stress loading conditions. Special experimental apparatuses are used to prevent specimens from buckling and to measure crack tip opening angle for thin compact tension (CT) specimens.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.345-350
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• 2001

In order to perform elastic-plastic fracture mechanical analyses, fracture resistance curves for concerned materials are required. 1T-CT specimen was used to obtain fracture resistance curves. But the fracture resistance curve by the 1T-CT specimen was very conservative to evaluate the integrity of the structure. And fracture resistance curve was affected by the specimen geometry and crack plane orientation. The objective of this paper is to be certain the conservativeness of the fracture resistance curve by the 1T-CT specimen and to provide the additional safety margin. For these, the fracture tests using the real pipe specimen and standard 1T-CT specimen test were performed. 4-point bending jig was manufactured for pipe test and direct current potential drop method was used to measure the crack extension and length for pipe test. From the pipe and the 1T-CT specimen test results, it was observed that the J-integral of the 1T-CT specimen test at the crack initiation point was very small compare to that of the pipe specimen test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1829-1834
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• 2001

The aim of this study is to investigate the ductile fracture behavior under mixed mode (I/II) loading using SA533B pressure vessel steel. Anti-symmetric 4-point (AS4P) bonding tests were performed to obtain the J-R curves under two different mixed mode (I/II) loadings. In addition, the fractographic examination of fracture surfaces was carried out to compare with those of pure Mode I and Mode II. In conclusions, the J-R curves under Mixed Mode (I/II) loading were located between those of Mode I and Mode II loadings. When the mixture ratio of mixed mode (I/II) loading was high, the J-R currie of mixed mode (I/II) loading approached that of pure mode I loading after some amount of crack propagation. In contrast with the above fact, if the mixture ratio was low, the J-R curve looked after that of pure mode II loading. The fractographic evidences such as the shape of dimples under different loading conditions supported these conclusions.