• Journal of Conservation Science
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• v.32 no.2
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• pp.223-234
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• 2016

Two-component epoxy resin is widely used in the cultural heritage restoration field. However according to mixing ratio of resin and hardener, curing property, mechanical strength and chemical structure differ which have possibility to effect the stability of cultural heritage. Result of questionnaire survey shows hands-on workers in the conservation field tend to mix the epoxy resin with his or her eye measurement when the using amount is small or mix additional hardener to shorten the pot life of epoxy resin. This research aims to analyze the curing property, mechanical strength and chemical structure of rapid curing type epoxy resin and medium curing type one depending on relative ratio of 0.25~4 of hardener to resin. When the amount of hardener was 0.5~2 times more than the resin, exothermic heat and curing speed were both increased. In case of included hardener to resin was lower than official ratio, mechanical strength (tensile shear strength, tensile strength and compressive strength) became higher along with active cross-linking bonding of the epoxy resin. Medium curing type epoxy relatively had lower exothermic heat and slower reaction during curing process. It was observed to be put to definite point of mechanical strength under lower content of hardener than official ratio. While, hardener ratio more than twice the resin slowed down the curing greatly and lowered the adhesion strength also. In conclusion, under the lower mixing rate of hardener than official ratio would show relatively fast reaction with similar mechanical strength. Over the official ratio on the other hand, material property drops rapidly. Accordingly, mixing ratio of epoxy resin is expected to be influential to the stability of cultural heritage.

• Journal of Animal Science and Technology
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• v.48 no.4
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• pp.603-610
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• 2006

This study was conducted to investigate the feeding effect of selenium provided by different sources on the physico-chemical properties of M. longissimus thoracis. Twenty Hanwoo steers(20～24 months, approximately 613kg) were assigned to 4 different feeding groups of each five, depending on the sources of selenium such as inorganic selenium(sodium selenite), organic selenium(Yeast, USA Sel-Plex), Se-SMC(Se-spent mushroom compost) and the control(no selenium). The selenium level in feed was 0.9 ppm for all groups except the control. Animals were fed with different feeding treatments for 12 weeks and slaughtered at National Livestock Research Institute. The inorganic selenium group had the highest cooking loss(CL. %) and followed by the Se-SMC group and organic selenium group. No significant differences in chemical composition, WB-shear forces, water-holding capacity(WHC) and sensory properties were found among the groups(P>0.05). There were 40% frequencies of grade A in the inorganic selenium group and followed by the organic selenium group(20%). Se-SMC group had 80% of frequencies for grade 1+ and followed by the inorganic selenium group(40%), whereas the organic selenium group and the control group had the 20% frequencies for grade 1+. From the results of this study showed that the selenium sources did not affect chemical composition, WHC and tenderness of Hanwoo steers. However, the inorganic selenium group had the highest cooking loss(%) and lowest pH when compared to the other groups.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.333-341
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• 2014

Since distribution and preservation of cultural artifacts in the submarine sediments are directly affected by not only ocean currents and tides, but also their composition, it is very important to investigate geological characteristics of sediments and ocean-sediment interactions for maritime archaeological survey. Physical properties of submarine sediments, which are collected by grab sampler and vibro-corer, are analyzed in order to investigate effects of submarine environment on development of maritime archaeological survey techniques. Result of physical property analysis showed that bulk density, shear strength, and magnetic susceptibility increase with depth, while water contents and porosity decrease with depth. Since the magnetic susceptibility of bedrock is about 40 times that of submarine sediments, it might impact greatly on the response of magnetic survey. Physical properties of sediments with depth and sediment classification by Folk's ternary diagram indicate that submarine sediment mainly consists of silt, and cultural artifacts can not penetrate no deeper than 1.5 m in sediments.

• Korean Journal of Poultry Science
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• v.38 no.1
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• pp.51-57
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• 2011

This study was conducted to investigate the effects of supplementation diets of pine needle powder on performance, proximate composition, carcass characteristics, blood cholesterol concentration, TBARS (thiobarbituric acid reactive substance), WHC (water holding capacity), and shear force of chicken meat. Broiler chicks were fed diets for five weeks containing 0% pine needle powder (Control), 0.3% pine needle powder (T1), 0.6% pine needle powder (T2), and 0.9% pine needle powder (T3). Performance was no significant difference among treatment groups, but mortality was decreased in diets by the supplementation of pine needle powder than that of T1 and control. The moisture, crude protein, crude fat, and crude ash were no significant difference. The liver weight and abdominal fat was significantly decreased by the supplementation of pine needle powder compare to the T1 and control (P<0.05). The total cholesterol and LDL-cholesterol concentration of control was higher than treatment groups, and the HDL-cholesterol concentration and glucose of control was lower than treatment groups (P<0.05). The TBARS value was significantly decreased by the supplementation of pine needle compared to the control (P<0.05). In conclusion, these data indicate that 0.6% pine needle powder supplementation (T2) was most effective in decreasing mortality, total cholesterol and LDL-cholesterol and increasing HDL-cholesterol concentration.

• Journal of Animal Science and Technology
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• v.49 no.4
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• pp.509-514
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• 2007

This study was conducted to investigate the optimal energy level at growing Korean black goat from April 20 to November 6, 2006. Forty male Korean black goat were divided into four treatments and were fed with concentrate feed containing ME 2.4, 2.6, 2.8 and 3.0 Mcal/kg with CP 15% and rice straw. Average daily gains of were 59.8, 65.4, 73.2 and 77.2 g/day in groups fed with ME 2.4, 2.6, 2.8 and 3.0 Mcal/kg diet, respectively. There was a tendency to increase ADG as the ME level of concentrate feed grew. Dressing percentage were 49.73, 48.64, 50.19 and 51.36% in each group, and were increased as the ME level grew. Meat percentage ranged between 53.1 and 55.3%, and were almost constant. Ranges of crude fat contents and water holding capacity were and 57.9~59.0%, which were increased as the ME level grew. On the other hand, shear force were between 2.8 and 3.1 kg/cm2, which were decreased as the ME level grew. These results suggest that the optimal energy level at growing goat's concentrate is ME 3.0 Mcal/kg.

• Journal of Embryo Transfer
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• v.16 no.3
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• pp.193-201
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• 2001

This study was designed to examine the factors affecting in fertilization and development of embryos in vitro, and to examine whether zone drilling by laser irradiation can improve the hatching rate of IVF embryos from DNA marker-proved Hanwoo. DNA markers related to marbling score were identified using DNA fingerprinting with Ml3 probe and restriction enzyme Hae III. Oocytes were aspirated from immature ovarian follicles using a combined method of rectal ovarian-palpation and transvaginal ultrasound-guidance(6.5MHz) under local anesthesia. The aspirated oocytes were washed twice with fresh D-PBS containing 5% FBS and were rewashed 4 to 5 times with TCM-199 containing 5% FBS. A morphological grade of I to IV was assigned to each oocyte. Data were analyzed using the GLM procedure of SAS. Sperm separation methods did not have any significant effect on cleavage or developmental abilities of IVF embryos. Significantly(P<0.05) higher cleavage rate was observed in embryos from GI(60.0%, 3/5), GII(69.2%, 18/26) and GIII(62.1%, 59/95) compared to embryos from GIV oocytes(36.2%, 25/69). And the developmental rate to blastocyst stage was higher(P<0.05) in embryos from GI(33.3%, 1/3) and GII oocytes(38.9%, 7/18) than those from GIII(16.9%,10/59) and GIV oocytes(4.0%, 1/25). There was no significant difference in development of IVF embryos to blastocyst by media for in vitro culture. Proportion of hatched blastocyst was significantly(P<0.05) higher in embryos received zona drilling by laser than those of non-drilled.

• Geotechnical Engineering
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• v.10 no.4
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• pp.119-132
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• 1994

Undrained cyclic triaxial tests were performed on silt contained in the sand in order to investigate the effect of silt contents on the liquefaction strength and shear characterist ifs of the sand. As the result of this experiment, the weakest percentage of silt contained in the sand was 30% for all the relative density considered in the test. Also, the same bests were performed to find the effect of cyclic speed applied ranging from 0.1Hz to 5Hz on the liquefaction strength. The more the silt is contained in the sand, the greater the liquefaction strength was affected by cyclic speed, While the silt -containing sand was far less influenced by the cyclic speed than clay containing sand. These results are believed to be caused by the change of pore water pressure of the effective stress path.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.9
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• pp.1452-1461
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• 1997

The hot press apparatus to obtain the solidified rocks with 60mm of diameter against rock waste was developed, and the optimum conditions for solidification were founded out, of which were 300.deg. C of temperature and 1hr of holding time. The solidified rocks reinforced with the fibers (carbon, steel) were made by means of a hydrothermal hot press method. Fracture toughness of those was obtained using the round compact tension(RCT) specimens. Load and displacement behaviours of the solidified rocks reinforced with the fibers were dependent upon the fiber volume fraction and kind of the fibers. Strength and fracture energy of the solidified rocks with steel were much larger than those of the solidified ones with carbon because of the Bridge's effect, multiple cracking and crack branching phenomena.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05a
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• pp.57-61
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• 2010

In this study, many concrete specimens were tested to investigate the variations of strength characteristics of high-strength concrete due to amount of recycled coarse aggregates, and to investigate the effect of steel-fiber reinforcement on concrete using recycled coarse aggregates. Test results showed that all of the variations of compressive, tensile and flexural strength appeared in linear reduction according to icrease the amount of recycled coarse aggregates, and steel-fiber reinforcement of 0.75% volumn of concrete recovered completely spliting tensile strength and flexual strength and recovered greatly compressive strength of concrete using recycled coarse aggregates of 100% displacement. And test results showed that the shear strength falled rapidly at 30% of replacement ratio so far as 34% of strength reduction ratio, but after that it falled a little within 3% up to the replacement ratio 100%, and steel-fiber reinforcement of 0.75% of concrete volumn recovered completely the deteriorated shear strength, moreover improved the shear strength above 50% rather than that of concrete using natural coarse aggregates.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1039-1046
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• 2005

After clay particles have been sediment isotropically, the clay deposits have been consolidated under $K_0$-stress system. Therefore, in order to predict the behavior in-situ of normally consolidated clays, the laboratory test should be enforced under $K_0$-stress system and should obtain the characteristics of normally consolidated clays. And relationship of stress-strain on clay is effected on not only method of consolidation but also characteristic of visco-plastic behavior. Saturated clay is effected more this trend. So, rate of strain is considered to understand exact stress-strain relationship. In this study, the series of undrained triaxial compression tests were preformed on remolded specimens which was made by slurry of clay, consolidated under $K_0$-stress systems. And the undrained triaxial compression test were preformed to examine behavior of stress-strain relationship due to rate of shear strain relationship due to rate of shear strain.