• Journal of Korea Foundry Society
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• v.8 no.4
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• pp.429-436
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• 1988

The influences of some casting conditions on bonding ratio and state at bonding zone of stainless steel-cast iron dual tube produced by centrifugal casting process were investigated to estimate fabrication technics. 1) Bonding ratio is increasing such as increasing of inner surface temperature of outer metal(stainless steel STS 304), if pouring temperature of inner metal (cast iron) is constant. 2) The more pouring temperature of inner metal (cast iron) increase, the more bonding ratio increase when inner surface temperature of outer metal (cast iron) is constant. 3) As the mold rotary speed is increase, the hatching area of bonding map (perfect bonding area) goes down to the low pouring temperature of inner metal. 4) In order to predict bonding state of two different metal, we are able to make and use the bonding map about casting conditions such as inner surface temperature of outer metal, pouring temperature of inner metal and mold rotary speed.

• Journal of Sericultural and Entomological Science
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• v.46 no.2
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• pp.65-71
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• 2004

Long term preservation experiment through refrigeration was conducted for 2 year on 300 lines of silkworm races preserved, as one method for the development of long term safe preservation technique. Experiment with 6 treatments was conducted for 680 days from July 1 st 2000 to May 1st 2002. Embryonic development was conducted to each treatment. There are no differences among treatments and races in 400 days preservation, the stage of whole embryonic development was Eul B and condition of eggs was good. In 650 days preservation experiment, differences were reveled among races and treatment, the level of whole embryonic development was Byeong A and condition of eggs was good. The order of embryonic development is European races >Tropical, Korean races >Japanese, Chinese races, thus European races showed fast embryonic development. Control(treatment A) and treatment C showed faster development than other treatments. And treatment D and F showed stable individual stage among all treatments. The test of shape characteristics and embryo which were conducted in hatching period showed 61% of high line succession possibility in average of 6 treatments. But treatment A and B showed no hatching, 3 lines of treatment C, 48 lines of treatment D, 1 line of treatment E, and 29 lines of treatment F showed slow development. And treatments D and F which showed stable embryo condition had highest possibility. The two treatments D and F showed good result among six treatments, and the preservation period of treatment D and F are 235 days and 310 days, and exposure period in $-2.5^{\circ}C$...was longer than other treatments. Numbers of hatched lines of treatment D and F are 48 and 29, and occupied 15.6% and 9.4% of all tested lines, respectively. Average hatching ratio of treatment D and F were 54.% and 71.6%, and average dead egg ratio were 12.6% and 2.4%, respectively. These results show that average ratio of hatching dead eggs in treatment D and F are higher than general line. Thus reconsideration of hatching condition on treatment D and F is needed.

• Korean Journal of Veterinary Research
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• v.34 no.2
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• pp.375-379
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• 1994

A teratogenicity test of 'folpet' was carried out in the developing chick embryos to investigate and validate the safety of rural environmental hazardous materials. Folpet was administered to chick embryos' yolk sac at a rate of 0.1mg and 0.01mg per SPF eggs at 96 hours of incubation. The morphological changes were examined. Fertility ratio of SPF eggs used was 94.9%. Hatching rate of untreated control group was 74.4% and the group dosed with 100ul of corn oil into the yolk sac was 70.0%. The $LD_{50}$ of folpet was 0.663mg/100ul/egg. After hatching, mean body weight, body length, claw length and beak length of high and low dose administered groups were not significantly different from untreated and vehicle control group. There was no abnormal appearence in all the groups. Therefore it seems that, within the doses applied, folpet dose not induce potential teratogenicity in the developing chick embryos.

• Journal of Sericultural and Entomological Science
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• v.35 no.2
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• pp.93-99
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• 1993

Studies were carried out to investigate physiological and biochemical analysis of recessive lethal mutant "nmn" and to observe the cuticle formation and dermal gland. All nmn homozygous larvae continued to eat a few mulberry leaves, and died without entering into molt. In case of artificial hatching, eggs had a higher nmn individual segregation ratio than in hibernating eggs. The percentage of nmn individuals with the hatching days was alike during 3days period. As a result of histological observation, nmn mutants dermal gland was different from normal dermal gland in form and size. Normal was formed new cuticle in the middle of the molting, but not in nmn mutant. Total protein content in haemolymph of the normal larva was more than that of nmn smutant and there was a difference between normal and nmn mutant protein components.omponents.

• Journal of Animal Reproduction and Biotechnology
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• v.36 no.1
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• pp.2-8
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• 2021

Dimethachlor is a synthetic herbicide, belonging to the chloroacetanilide group, that inhibits the undesirable growth of weeds via the suppression of very long-chain fatty acid synthesis. Although dimethachlor has been shown to run off from agricultural fields into aquatic ecosystems, the toxicity of dimethachlor on aquatic invertebrates and vertebrates is unknown. In our study, we assessed the toxicity of dimethachlor on developing zebrafish embryos by analyzing viability, hatching ability, and phenotypic changes. Embryonic viability decreased from 48 h post-fertilization (hpf) at the highest concentration of dimethachlor. Decreased hatching ratio, shortened body length, and pathological changes in the eye, heart, and yolk sac were observed at sub-lethal concentrations. Additionally, dimethachlor increased the number of apoptotic cells and level of reactive oxygen species 120 hpf. Our results indicate that dimethachlor may act as an anti-developmental toxicant when accumulated in an aquatic environment.

• Korean Journal of Poultry Science
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• v.24 no.3
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• pp.117-126
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• 1997

This study was conducted to estimate the hatching and growing performance, and heterosis of Korean Native Chicken(KNC), Rhode Island Red(RIR) and KNC XRIR crossbred. A total of 1,274 female pullets were produced from KNC, RIR and KNC x RIR crossbred kept in National Live-stock Research Institute, Korea. The experiment was conducted for 20 weeks from Sep. 2, 1995 to Jan. 20,1996. Hatchabilities of KNC dark brown strain x RlR(DR), KNC light brown strain x RlR (LR) and KNC dark black strain x RlR(BR) were 77.3%, 73.6% and 72.5%, respectively. Viabilities up to 20 weeks of age were not significantly (P>0.05) different among purebreds and crossbred. Body weights of DR, LR and BR were 1,890 g, 1,849 g and 1,967 g, respectively, at 20 weeks of age. The feed conversion ratio(feed /gain) of DR, LR, and BR were 5.88, 6.07 and 5.87, respectively, up to 20 weeks of age. Average shank lengths of DR, LR and BR were 97.1 mm, 98.9 mm and 99.4 mm, respectively, at 20 weeks of age. The heterosis effects were estimated to be -0. 48%, and 12.58%, respectively, in fertility and hatchability. Up to 20 weeks of age, the heterosis effects were estimated to be 0.07%, 13.49%, -5.77%, and 3.52% in viability, body weight, feed conversion ratio, and shank length, respectively.

• Journal of Aquaculture
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• v.9 no.4
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• pp.429-435
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• 1996

We investigated the effects of rearing water temperatures during sex differentiation period on sex ratios in olive flounder, Paralichthys olivaceus. Control and gynogenetic diploid juvenile flounder reared at water temperature of 18, 21, 24 and $27^{\circ}C$ for 65 days from 35 to 100 days after hatching. Fish were sampled to examine sex ratios at 195 or 260 days after hatching. Female ratios of control and gynogenetic diploid flounder declined rapidly as water temperature increased. Sex ratio of gynogenetic diploid reared at $27^{\circ}C$ was very close to 1 : 1 ratio (P<0.01), The survival rates of control and gynogenetic diploid reared at $27^{\circ}C$ were different from other water temperature groups. The growth of body weight of control and gynogenetic diploid reared at $18^{\circ}C$ were different from other water temperature groups.

• Journal of Environmental Health Sciences
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• v.33 no.6
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• pp.488-492
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• 2007

The influence of additive materials including saw dust and cow manure in the ripening of leather sludge for the efficient vermisabilization was studied. The ripening characteristics of the leather sludge, the growth of earthworms in the growth bed and the by-products like cast were observed according to the mixing ratio of additive materials. When the mixed leather sludge of which the additive materials contents were over 20% were ripened for 50 days, the values of ORP and alkalinity were changed to the favorable ranges for earthworms, the positive (+) and below 1,000 mg/l as $CaCO_3$, respectively. The velocity of ripening improving the characteristics of the leather sludge was faster in the sludge mixed with cow manure than saw dust. This results could also be verified from the monitoring of the states of earthworm growth using the survival rate, the increase rate of lifeweight and the hatching rate of earthworm cocoon in the their growth bed packed with the ripened sludge. The values of CEC in cast, the vermi-stabilized sludge, were increased with the mixing ratio of additive materials, but the content of heavy metals was drcreased by the dilution effect and accumulation in the earthworm body. Above results show that the leather sludge might be efficiently stabilized by earthworms through the ripening for 50 days using additive materials. Cow manure can be used as a good additive materials for leather sludge as much as saw dust, and the optimum content of additive materials in the well-ripened leather sludge was about 30%.

• Korean Journal of Poultry Science
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• v.44 no.3
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• pp.161-172
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• 2017

This study was conducted to determine the effect of Saccharomyces cerevisiae (SC) as a dietary probiotic and evaluated the most suitable feeding interval for this probiotic on growth performance, carcass yield, and meat quality parameters in broiler chickens. In total, 1,050 one-day-old Cobb 500 chicks were randomly assigned to one of seven dietary treatment groups, in a $2{\times}3$ factorial arrangement with 3 SC dosages (0.6%, 1%, and 1.4%) and two feeding intervals [long term (LT) for 35 days and short term (ST) for 28 days after hatching], with a negative control diet (NC; 0% SC). Triplicate experiments were performed with 50 birds per cage. Broilers fed a diet including SC showed increased (p<0.01) daily gain and feed efficiency compared to the control. Further, broilers fed the 1.4% SC supplemented diet showed a significantly increased (p<0.01) average daily gain (ADG) and feed conversion ratio (FCR) compared to broilers fed the 0.6% and 1% SC incorporated diets. Similarly, broilers fed an LT SC diet showed a greater (p<0.01) increase in ADG and FCR compared to broilers fed an ST SC diet. Moreover, broilers fed an LT SC diet displayed a reduced (p<0.05) meat pH, gizzard weight, and increased (p<0.05) meat water-holding capacity compared to broilers fed an ST SC diet. Broilers fed the 1.4% SC supplemented diet showed increased (p<0.05) thigh muscle weight compared to broilers fed the 0.6% and 1% SC supplemented diets. In conclusion, broilers fed LT SC diets showed improved growth performance and carcass quality parameters compared to broilers fed ST SC diets, and the NC diet, from hatching to day 35.

• Journal of Aquaculture
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• v.10 no.2
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• pp.179-187
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• 1997

Early development growth and sexual phenomena of the hybrid between male spotted flounder (Verasper variegatus) and female olive flounder (Paralichthys olivaceus) were investigated. The hybrid produced was newly called the "Bumnupchi" in Korean name, "Mottled flounder" in English name. Fertilization rate, hatching rate and early survival rate of the mottled flounder were 56.9~72.3%, 86.7~92.5% and 89.1~96.0%, respectively. At 50th day and 240th day after hatching, they were 2.1$\pm0.2cm\;and\;22.9\pm2.1cm\;in\;total\;length, \;0.10\pm0.002g\;and\;179.0\pm38.5g$ in body weight, respectively. Eye position of the mottled flounder was mixed with both dextral (77.7%) and sinistral type (22.3%). Gonads were differentiated into ovarian type and testis type at 80th day after hatching, and its ratio was 1:1 (P>0.05). Most Gonads seemed to be sterile without having germ cell, whereas only 3.6% of investigated indiciduals turned out to have oocytes in the gonad. When the induction of sex reversal were attempted by daily oral administration of $17\beta$-methyltestosterone (0.5mg/kg fish) andestradiol-17$17\beta$(0.5mg/kg fish)from 40th to 100th day after hatching, both testis and ovary type were induced 81.9% and 87.7% of each hormone-treated fish, respectively.fish, respectively.