• Tribology and Lubricants
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• 제35권2호
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• pp.139-147
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• 2019

This study investigates the effects of corrosion resistance characteristics of opponent materials in relative motion on the sliding wear behavior of mild carbon steel. Pin specimens made of mild carbon steel are tested at several sliding speeds against mating discs made of two types of alloyed steels, such as type D2 tool steel (STD11) and type 420 stainless steel (STS420J2), with different corrosion resistance characteristics in a pin-on-disc type sliding wear test machine. The results clearly show that the sliding wear behavior of mild carbon steel is influenced by the corrosion resistance characteristics of the mating disc materials at low sliding speeds. However, the sliding wear behavior at high sliding speeds is irrelevant to the characteristics because of the rising temperature. During the steady state wear period, the sliding wear rate of mild carbon steel against the type 420 stainless steel at a sliding speed of 0.5 m/s increases considerably unlike against the type D2 tool steel. This may be because the better corrosion resistance characteristics achieve a worse tribochemical reactivity. However, during the running-in wear period at low sliding speeds, the wear behavior of mild carbon steel is influenced by the microstructure after heat treatment of the mating disc materials rather than by their corrosion resistance characteristics.

• 농업과학연구
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• 제44권4호
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• pp.519-524
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• 2017

The present study investigated the impacts of mating age of gilts (A1, < 230 days; A2, 230 - 249 days and A3, $250{\leq}days$) on reproductive performance and litter size of sows at farrowing to weaning. A total of 102 crossbred gilts ($Yorkshire{\times}Landrace$; average days old, 90 days) were purchased from a commercial breeding company. After identification of third estrus, the gilts were artificially inseminated using semen of Duroc boars. Pregnant pigs were allotted to one of three groups including A1, A2, and A3. Experimental diets and water were fed ad libitum during each experimental period which included the first, second, and third parities. Backfat thickness (BFT) of sows was higher in A3 at farrowing in the first parity than in others. At weaning time in the second parity, sows in A3 group showed a numerically higher BFT than those in A1. There was no effect of mating age on the total number of piglets born and total weaned piglets. There was a tendency to decrease the wean-to estrus-interval in the first parity as age increased at mating. Results obtained in the present study indicate that the first mating age does not affect the subsequent parites' reproductive performance; however, weaned to estrus interval tended to decrease in A2 at the first parity.

• Asian-Australasian Journal of Animal Sciences
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• 제16권12호
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• pp.1725-1731
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• 2003

Effect of strategically supplemented pregnancy allowance was ascertained during different phases of gestation on the reproductive performance of does. Gravid does (18) were allotted to 3 dietary treatments HH, HL and LH in a completely randomized block design. All does were provided wheat straw ad libitum and supplemented with concentrate mixture at the rate of $20g/kgW^{0.75}$ from 0-60 days post-mating. Subsequently, HH group was given concentrate at the rate of $40g/kgW^{0.75}$ from 61 d post-mating to term. HL group was offered concentrate from 61-90 d post-mating and 121d post mating to term at the rate of $20g/kgW^{0.75}$ and from 91-120 d post-mating at the rate of $40g/kgW^{0.75}$. LH group was provided with concentrate from 61 to 120 d post-mating and 121 to term at the rate of 20 g and $40g/kgW^{0.75}$, respectively. Mean total dry matter and concentrate intake ($g/kgW^{0.75}$) was significantly higher on HH in comparison to comparable intake of HL and LH treatments, however, wheat straw followed the reverse trend. Haematological and biochemical parameters except serum glucose, total serum protein and A:G ratio did not differ significantly among dietary treatments. The gross gain in weight, products of pregnancy at 21 weeks of gestation, pregnant does average daily gain, birth weight of kids and survivability of kids were significantly lower in treatment HL in comparison to comparable values for HH and LH treatments. The net gain in gravid does was significantly higher in treatment HH than the comparable values obtained in HL and LH treatments. The last month of pregnancy was found to be nutritionally most sensitive period of gestation for native goats.

• Toxicological Research
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• 제12권1호
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• pp.93-99
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• 1996

The effect of KTC-1, a new semisynthetic rifamycin antituberculous drug, on general toxicity, reproductive capability and fetal development was investigated in Sprague-Dawley rats. Male rats were administered KTC-1 with mashed feed from 63 days before mating to the end of mating period, and female rats were given from 14 days before mating to day 7 of gestation at dose levels of 0, 375, 750, and 1,500 ppm. The females were sacrificed on day 21 of gestation for examination of their fetuses. At 1,500 ppm, a reduction in body weight gain and testis atrophy were observed in male rats. Histological examination revealed testicular atrophy, absence or decrease of germinal cells, and vacuolization of Sertoli cells in testis. A reduction in body weight gain, a decrease in food consumption were found in female rats. In addition, decreases in the number of corpora lutea, iraplantations, and the litter size of live fetuses were seen. Mating, fertility, and pregnancy performances were also affected. There were no external abnormalities observed by examination of fetuses. At 750 ppm, a reduction in the body weight gain of male and female rats and decreases in the number of implantations and litter size were found. At 375 ppm, no treatment-related effects were observed. The results suggest that the no-effect dose levels (NOELs) of KTC-1 are 375 ppm for males and females on general toxicity, 750 ppm for males and females on reproductive capability, and 375 ppm for fetuses on embryonic development.

• Biomolecules & Therapeutics
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• 제4권4호
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• pp.297-300
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• 1996

LBD-001, a recombinant human interferon $\gamma$ produced by genetically engineered yeast as a host system, was administered intraperitoneally to Sprague-Dawley male rats from premating to mating period at least for 60 days and to female rats from at least for 2 weeks before mating to early gestation period (from day 0 to 7 of gestation) at dose levels of $0.35\times10^6, 0.39\times10^6, and 1.38\times10^6$ I.U./kg/day. In the positive control group, ethynylestradiol ($EE_2$; 40 $\mu\textrm{g}$/kg/day) was subcutaneously administered only to female rats during the early gestation period. Effects of the test agents on reproductive performances of the male or female rats and embryonic development were as followings; (1) No significant changes by the treatment of LBD-001 were observed in general behaviors, body weight, food and water consumption, and necropsy of parent animals. However, significant decreases of body weight, food consumption, and water consumption were observed in ($EE_2$ -treated female rats. (2) Mating performances and fertility of parent animals were not significantly affected by the treatment of LBD-001. In ($EE_2$ -treated females, however, the fertility was completely inhibited. (3) No changes in resorption rate and external abnormality of F1 fetuses were observed by the treatment of LBD-001. The results show that LBD-001 at the dose of $1.38\times10^6$ I.U./kg/day or less does not affect general toxicity and reproductive function of parent animals and embryonic development of F1 fetuses.

• Animal cells and systems
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• 제13권1호
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• pp.71-78
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• 2009

To clarify the reproductive function of vibration signals in Hynobius, which has externally fertilized eggs, we quantitatively analyzed the body and tail undulations of male Korean salamanders (Hynobius leechii) in sixteen mating events. One large and one small male, and one female were used in each mating event. We analyzed behaviors recorded over a total of 3 hrs for each mating event; 2 hrs before and 1 hr after female's oviposition. Males touched females using their snouts or body trunk throughout the entire mating periods, but females touched males increasingly more after approximately 1 hr before oviposition. Males conducted body undulations more than 50 times per 10 minutes at a mean frequency of 0.64 Hz. Large males conducted more body undulations than small males, particularly on the tree twig where females attached their egg sacs. Males responded to other males' body undulation throughout the mating period by orienting their head towards, approaching, and touching the undulating male. Females only responded for about 10-20 min before ovipositing, and most responses were directed to the large male's body undulation. Males conducted tail undulations 3.0 times per 10 min at a mean frequency of 1.7 Hz and most tail undulations occurred after one male bit the other male. These results suggest that body undulations function in both male-female and male-male interactions, while tail undulations mainly functions in male-male competition. Also, male H. leechii appear to actively attract females, while females respond to the males only at times close to oviposition.

• 한국환경생태학회지
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• 제35권6호
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• pp.594-600
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• 2021

본 연구는 국내 매미아과를 대상으로 번식울음 시기를 전국적으로 관측하여 종별 출현 시기 및 서식지 분포 특성을 밝히는데 그 목적이 있다. 연구대상지는 전국 보호지역 19개소이었다. 매미 번식울음 수집기간은 2019년 12개월간이었다. 매미 번식울음 녹음은 매시간당 1분씩 WAV, 44,100Hz 포맷으로 생물음향 측정장비를 설치하여 녹음하였다. 온도는 미기상 측정장비를 이용하여 시간당 1~2회씩 기록하였다. 연구대상종은 국내 매미아과 9종이었다. 번식울음 분석은 매미종별 번식울음 시종점을 기록하였다. 분석 결과, 연구대상지 19개소에서 출현한 매미는 9종이었다. 종별 번식울음 시기는 말매미(7/12~9/30), 애매미(7/27~10/20), 참매미(7/25~10/9), 유지매미(7/28~9/5), 털매미(7/3~9/29), 늦털매미(9/14~10/30), 소요산매미(6/26~8/2), 참깽깽매미(7/27~9/28), 쓰름매미(8/8~9/11) 순이었다. 종별 번식울음 기간은 35일(쓰름매미)~89일(털매미) 사이었고 평균 62일이었다. 종별 서식지 해발고도는 말매미(5~386m), 애매미(7~759m), 참매미(7~967m), 유지매미(42~700m), 털매미(7~700m), 늦털매미(5~759m), 소요산매미(7~759m), 참깽깽매미(397~967m), 쓰름매미(7~42m) 순이었다. 종별 서식지 평균온도는 말매미(23.9℃), 애매미(21.8℃), 참매미(22℃), 유지매미(23℃), 털매미(22.9℃), 늦털매미(14.6℃), 소요산매미(20.6℃), 참깽깽매미(19.3℃), 쓰름매미(24.4℃) 순이었다. 종별 서식지 분포는 애매미, 참매미, 털매미는 전국 15개소 이상 분포하였다. 말매미는 서남부 저지대에 분포하였다. 유지매미는 한반도 서부 지역에 분포하였다. 늦털매미는 고산지대와 동남부 일부를 제외한 지역에 분포하였다. 소요산매미는 산지에 가까운 지역에 분포하였다. 참깽깽매미는 고산지대에 국지적으로 분포하였다. 쓰름매미는 평지형 습지에 국지적으로 분포하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제7권4호
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• pp.563-570
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• 1994

Fifty-one Thai Native (TN) and Anglo-Nubian (AN) $\times$ TN does were studied. The purpose of the study was to investigate the reproductive performances of different goat genotypes grazing improved pasture with or without supplementary feeding. The feeding regimes were: 1. no concentrate supplement (T1), 2. supplemented for 15 days before mating and 45 days during mating period (T2), 3. supplemented from 15 days before mating to 42 days after kidding (T3) and 4. supplemented for 30 days before kidding, followed by 42 days after kidding. Cross-bred does tended to have higher conception rates, kidding opportunities and higher multiple birth rates than TN does. However, these differences were not statistically significant (p>0.05), and concentrate supplementation under the various regimes did not increase reproductive performance. TN kids had significantly (p<0.01) lower birth weights and lower weights at 3, 6 and 12 weeks of age than those of the cross-bred kids. However, there was no significant difference between the genotypes in growth rate (g/d or $g/kg^{75}/d$) of kids during these periods. Supplementary feeding did not significantly affect either kid birth weight or weight gain in the first 6 weeks after birth and during this period supplementary adequate in both quantity and quality, substantial reproductive performances were achieved from both TN and AN $\times$ TN does without concentrate supplementation.

• Biomolecules & Therapeutics
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• 제2권1호
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• pp.94-101
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• 1994

DA-125, a new anthracycline antitumor antibiotic, was at dose levels of 0, 0.03, 0.1 and 0.3 mg/kg/day administered intravenously to Sprague-Dawley male rats from premating to mating period and to females from premating to early gestation period. Effects of test agent on general findings and reproductive performance of parent animals and embryonic development were examined. No treatment-related changes in clinical signs, body weight, food consumption and necropsy findings were observed in all groups of both sexes. At 0.3 mg/kg, a decrease in the weight of spleen was found only in male rats. Mating performance and fertility of parent animals were not adversely affected by all doses tested. Fl fetuses showed no changes related to treatment of DA-125, except that at 0.3 mg/kg, an increase in the resorption rate was seen. The results show that the no effect dose levels (NOELS) for general toxicity of parent animals and fetal development are 0.1 mg/kg/day and NOELS for reproductive capability are over 0.3 mg/kg/day.

• Biomolecules & Therapeutics
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• 제4권1호
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• pp.51-58
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• 1996

A new composite antibiotic, SM-101(sulbactam.metampicillin), was at dose levels of 0, 250, 500 and 1000 mg/kg/day administered intravenously to Sprague-Dawley male rats from predating to mating period and to females from premating to early gestation period. Effects of test agent on general findings and reproductive performance of parent animals and embryonic development were examined. In male parents, two deaths occurred at 1000 mg/kg. The increase in kidney weight of the 1000 mg/kg group were also observed. The decrease in body weight and food consumption were found at 500 and 1000 mg/kg. The decrease in spleen weight were seen at 250, 500 and 1000 mg/kg. In female parents, three deaths were found at 1000 mg/kg. Mating performance and fertility of parent animals were not adversely affected by all doses tested. F1 fetuses showed no changes related to treatment of SM-101. The results show that the no effect dose level(NOEL) for general toxicity of parent animals is under 250 mg/kg/day and NOELS for reproductive capability and fatal development are over 1000 mg/kg/day.