• Journal of KSNVE
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• v.9 no.3
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• pp.593-599
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• 1999

A rotordynamic analysis is performed with a motor-bull gear rotor system supported on two partial bearings, which is intended to drive a high-speed turbo-chiller compressor impeller shaft through its built-in pinion gear. The motor-bull gear rotor system has a rated speed of 3,600 rpm, and is modeled utilizing the finite element method for analysis. As loadings on the bearings due to the gear action are significant in the system considered, each resultant bearing load is calculated statically by considering the generalized forces of the gear action as well as the rotor itself. The two support partial bearings are designed to take their varying loads along with their varying load angles, and they are also analyzed to give their rotordynamic coefficients. Then, a complex rotordynamic analysis of the motor-bull gear rotor-bearing system is carried out to evaluate its whirl natural frequencies and mode shapes and unbalance responses under various loading conditions. Results show that the bearings and entire rotor system are well designed regradless of operating conditions, i.e., loads and operating speeds.

• Korean Journal of Veterinary Research
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• v.33 no.4
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• pp.591-596
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• 1993

The smear preparations of the semen from Korean native bull and the tissue preparations of the organs from male and female mice were performed by fluorescent staining method. More than 600 spermatozoa per straw from two semen straw groups and more than 300 cells per mouse organ from two mice per sex were observed and then the ratio of spermatozoa bearing B-body and the cells bearing F-body were assessed, respectively. 1. The ratios of spermatozoa bearing B-body in semen of Korean native bull were $37.3{\pm}3.1%$. 2. The ratios of cells bearing F-body in the organs of mice were $63.5{\pm}4.5%$ in male tissues and $7.5{\pm}3.2%$ in female tissues. 3. The organs with higher appearance frequency of F-body were ordered as brain, kidney, stomach, lung, testis, liver, small intestine, spleen and pancreas in male mice and pancreas, small intestine, liver, brain, kidney, lung, spleen and stomach in female mice.

• Journal of Embryo Transfer
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• v.32 no.3
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• pp.243-248
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• 2017

Antioxidants have been added to cryoprotectant or in vitro culture medium for sperm to reduce the detrimental damage, such as reactive oxygen species. However, curcumin, an antioxidant, shows dual effect on the viability and progressive motility of bovine sperm exposed to hydrogen peroxide. Low concentration of curcumin increases sperm viability and progressive motility, whereas high concentration of curcumin reduces them. This study was performed to identify whether TREK-1 channel is related to low sperm viability and motility induced by high concentration of curcumin. Curcumin reduced TREK-1 channel activity in a dose-dependent manner. TREK-1 channel was expressed in sperm obtained from Korean native bull. Treatment with TREK-1 channel blockers, such as curcumin, fluoxetine, $GdCl_3$, and spadin, significantly reduced sperm viability and motility (p < 0.05). However, TREK-1 channel activators showed different effect; linoleic acid showed an increase in sperm viability and motility, and wogonin did not affect them. These results show that TREK-1 channel is involved in the regulation of sperm viability and motility. In particular, high concentration of curcumin might reduce sperm viability and progressive motility of Korean native bull through blockage of TREK-1 channel.

• Journal of Veterinary Clinics
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• v.40 no.1
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• pp.73-77
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• 2023

Rectal prolapse is encountered in all domestic animal species but clinical report regarding the condition in the elk is limited. A 10-year-old elk bull weighing 400 kg was referred to the Large Animal Hospital of Kyungpook National University with clinical signs including intermittent tenesmus related to rectal prolapse and anorexia for the previous 5 days. Type II rectal prolapse was diagnosed based on the history and clinical signs. An emergency resection and anastomosis including a purse string suture was performed under general intravenous (IV) anesthesia in field to prevent injury of the patient and the staff. The patient recovered uneventfully after the surgery without excitement. A systemic antibiotic and an anti-inflammatory drug were given to prevent postoperative complication and relieve pain. The follow up on the patient after 4 weeks of the surgery showed that the prolapse recurred due to intermittent straining after 2 weeks of the surgery. The patient was on the glucocorticoid for the following 3 days but was finally euthanized owing to the exacerbation of the prolapse 1 week after the recurrence. This report describes a rare case of rectal prolapse in an elk bull and the clinical outcome of the surgical repair in detail.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.1
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• pp.10-18
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• 2000

This paper describes the magnetic orientation of the intact and demembranated bull sperm treated by DTT or heparin in a 5,400 G static field. Semen samples collected from four bulls (Japanese Black) were mixed to the same sperm density. One percentage triton X-100 was used to extract the plasma membrane. The intact and demembranated sperm suspensions were treated with 20, 200, 2,000 mM DTT, 100, 1,000 or 10,000 units heparin solutions at $4{^{\circ}C}$ for 6 days. The decondensation of the sperm nuclei treated by DTT or heparin was examined by measuring the sperm head area at 1, 3, and 6 days. After measuring the area, each sperm sample was exposed to a 5,400 G static magnetic field generated by Nd-Fe-B permanent magnets for 24 hours at room temperature. Results showed that the decondensation of bull sperm nuclei was not induced by the heparin treatment, however, incomplete decondensation was induced by the DTT treatment. During the magnetic orientation, bull sperms treated by DTT or heparin had low percentages of long axis perpendicular to the magnetic lines of force. However, different aspects were obtained for long axis perpendicular orientations following treatment of DTT or heparin. Through the DTT treatment, the decline of long axis perpendicularly oriented percentages was due to the increase of long axis parallel orientation with the head of the flat plane perpendicular to the magnetic lines of force, whereas, using the heparin treatment, the decline of long axis perpendicular orientation was due to the increment of long axis parallel orientation with the head of the flat plane parallel to the magnetic lines of force. Also, percentages of the head of the flat plane perpendicular were decreased by the heparin treatment. These findings suggest that maintaining the structure of protamine in the chromatin is necessary for the sperm head to orient with its flat plane perpendicular, and maintaining the disulfide bond in the chromatin is necessary for the long axis of sperm to orient perpendicularly.

• Journal of Animal Science and Technology
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• v.44 no.5
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• pp.519-522
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• 2002

Body weight-age data from 60 bulls and 60 steer of Hanwoo in the Korean Native Cattle Improvement Center was used to determine the growth curve parameters with Gompertz equation. Estimated growth curve functions were as follows; Bul l : $W_t$ = 906.1.exp{－3.956.exp(－0.0034t)} Steer : $W_t$ = 823.1.exp{－3.301.exp(－0.0027t} Mature weight estimated with Gompertz equation of bull is higher than earlier studies. And the major factor raising differences from the other is feeding level. Relative body weights of steer to bull were rapidly decreased to 79.2% until 19.5 months of age, and then increased slowly. The ratio was 90.8% at mature state. Body weight was under-estimated for bull at birth, but over-estimated for steer, and the body weight variations of bull were larger than the steer.

• Korean Journal of Veterinary Research
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• v.31 no.1
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• pp.123-130
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• 1991

The present study was performed to investigate the effect of Ca ion concentration on sperm viability and acrosome reaction rate and to evaluate the effect of treatments using caffeine and Ca-ionophore A23187 on acrosome reaction rate in frozen-thawed bull spermatozoa. Viabilities of in vitro capacitated bull spermatozoa at 0, 2.25 and 4.5 mM Ca ion concenrations were 21.00, 26.00 and 22.59%, respectively and significantly higher in Ca ion 2.25mM added group than Ca ion free group (p<0.05) and acrosome reaction rates of in vitro capacitated bull spermatozoa were 17.09, 52.15 and 47.92%, respectively and significantly high in Ca ion added groups(p<0.05). Viabilities in vitro capacitation by caffeine and Ca-ionophore A23187 in control, caffeine treated group, Ca-ionophore A23187 treated group and caffeine+Ca-ionophore A23187 treated group were 37.91, 27.67, 22.33 and 25.59%, respectively and significantly higher in control than treated groups(p<0.05), there were no significant differences among the treated groups, and acrosome reaction rates were 10.33, 37.92, 48.09 and 57.17%, respectively and there were significant differences among the groups(p<0.05), especially higher in caffeine+Ca-ionophore A23187 treated group than others.

• Journal of Veterinary Clinics
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• v.16 no.2
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• pp.448-453
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• 1999

The three-dimensional structure of the Sertoli cell in the Korean native bull was investigated by scanning electron microscopy. Morphologically, four types of Sertoli cell processes were evident: 1) sheet-like processes, 2) sleeve-like processes, 3) bough-like processes and 4) finger-like processes. The sheet-like processes rested upon more than half of the surface of each spermatogonia, spermatocyte and spermatid. Sleeve-like processes, bough-like processes and finger-like processes are observed in the middle and apical portion of seminiferous tubule. All Sertoli cell processes are originated from Sertoli cell column. Just before spermiation, the apical sheet-like processes are shifted from their position at the spermatid head, and bough-like processes covered the disengaged residual body, after which the residual body was no longer evident in the tubule. Though the mechanism for this elimination is not known, the process suggests a reciprocity between the Sertoli and germ cells.

• Journal of Korea Foundry Society
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• v.8 no.4
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• pp.422-428
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• 1988

In this study we have investigated the effects of Mm, MmH and $MmH_2$ on the matrix development in cast iron, The conclusive summary is as follows: The spheroidal graphite was observed when 0.5wt.% or more of mischmetal was added and the matrix was of ledeburite structure, but bull's eye structure was not observed. On the other hand, the bull's eye structure was observed when 0.25wt.% of MmH, or 0.25wt.% to 0.5wt.% of $MmH_2$ was added. Above limit of the additives, the matrix changed into ledeburite structure. As the hydrogen content of mischmetal compound increased from MmH, the range of additives to obtain bull's eye structure expanded. This reveals the significant effect of mischmetal hydride on matrix development in cast iron and the possibility of practical use of the additives.

• Korean Journal of Veterinary Research
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• v.31 no.4
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• pp.485-490
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• 1991

A 7-year old Holstein bull showing marked thickening of left forelimb was diagnosed as pulmonary hypertrophic osteoarthropathy on the histological basis of the exostotic bone of left metacarphus. Thickening of the bone was due to apposition of excessive cancerous bone beneath the periosteum on the shaft. The lung lesion of the bull, chronic suppurative bronchopneumonia was possibly related to pathogenesis of the bone thickening.