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        검색결과 25

        1.
        2018.11 구독 인증기관·개인회원 무료
        To preserve the superior genetic resources and restore the endangered species, Somatic cell nuclear transfer (SCNT) has been used widely. In Korea, the research of dog cloning has made outstanding achievements including the production of the world`s first cloned dog. Sapsaree (Sapsalgae), the representative dog of Gyeongsan-si was designated as a Korea natural monument (No. 368). This male dog used in this study has azoospermia due to unknown cause. In this study, the aim was to confirm the cause of infertility in the cell donor dog and to evaluate the reproduction potential of dog cloning using infertile male dog by SCNT. First, to confirm the infertility of the cell donor dog, the reproductive history and the testis were evaluated. The breeding histology was not recorded in individual document. In histopathology, the Sertoli cell tumor was confirmed in biopsy of the cell donor dog after death. But, these tumors are predominantly in older dogs. Second, we produced the cloned dogs with the somatic cells of the infertile dog and the appearance was similar with the cell donor dog. Also, microsatellite analysis confirmed the genetic relationship between the cell donor and clone dogs. Third, the potential breeding capacity of the cloned dog was confirmed. In T4 assay, the normal dog (same age with cloned dogs), cell donor dog, and cloned dogs was investigated. The cell donor dog with azoospermia had very low T4 level, and cloned dogs showed higher level of T4 than normal dogs. In CASA, There was no significant difference in sperm motor ability between normal dogs and cloned dogs. As a result, cloned dogs produced by SCNT had no problem regarding the reproductive function of the testis. In AI experiment, the semen of clone dogs was used to fertilize a natural female bitch and was diagnosed pregnancy by ultrasonography. In total, 7 puppies were born by normal delivery (male: 3, female: 4). In conclusion, this study confirmed that the reproduction problem of non-genetic infertility can generate a normal descendant by SCNT. Also, the first successful research to restore infertile dogs was completed. Furthermore, SCNT would be useful for the restoration of endangered species and application of superior traits.
        4.
        2014.02 구독 인증기관 무료, 개인회원 유료
        Recently, the automobile industry need environmental standards and demands decrease of vehicle weight to reduce the environmental pollution. magnesium-Aluminum cast alloys are of commercial importance because of their various applications in the automotive industry. These alloys offer a combination of a high degree of achievable strength with excellent castability, light weight and good machinability with regard to both permanent molds and die castings forming. This paper show oxide distribution and deformation on casting condition of Mg elbow support. Moreover the microstructure of Mg elbow support is observed in the integrity assessment of porosity for nondestructive radiation x-ray.
        3,000원
        5.
        2013.08 구독 인증기관 무료, 개인회원 유료
        Materials design and processing development proposed in this study, aims at contributing to high wear resistant and friction characteristics. To find wear resistant and friction with inner elbow pipe, it is needed hardness and frictional condition test to be capable of supplying with high Cr casting steel. The result of HTV(heat treatment in vacuum) shows that hardness increased with increasing Cr content in % carbide phase. It was about 7∼10% of hardness improvement compared to original casting elbow pipe. This behavior of the hardness of Cr casting steel was explained by the types of chemical bonds that hold atoms together in Cr carbide phase. Through the friction coefficient and wear loss test, with the increasing of Cr wt% reduction in the coefficient of friction and wear loss.
        4,000원
        6.
        2013.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The smoke emission of biodiesel fuel was reduced remarkably in comparison with diesel fuel, that is, it was reduced approximately 36% at 2000rpm, full load condition. And, power, torque and brake specific energy consumption showed no significant differences. However, NOx emission of biodiesel fuel was increased compared with commercial diesel fuel. Also, the effects of exhaust gas recirculation(EGR) to reduce the NOx emission has been investigated. It was found that simultaneous reduction of smoke and NOx was achieved with biodiesel fuel(20vol-%) and cooled EGR method(10∼15%).
        3,000원
        7.
        2013.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The SMC(Sheet molding compound) process is widely used in the automotive industry to produce parts that are large, thin, lightweight, strong and stiff. Compression molded parts are formed by squeezing a glass fiber reinforced UP(Unsaturated Polyester) sheet, known as sheet mold compound(SMC), between two heated cavity surfaces. This paper has performed flow analysis to predict optimization process of low density SMC. After five types of design variables and six types of response variables were defined, DOE(Design of Experiment) and RSM (Response Surface Method) were applied in order to measure sensitivity of design variables and realize optimization through regression model. After design optimization, the total warpage of the SMC is reduced by about 12% compared to the initial design of SMC and cure time, cure temperature, clamping force and flow pressure are decreased by 0.6∼27% in comparison with the initial design. By doing this, the production costs could be diminished.
        4,000원
        8.
        2012.06 구독 인증기관·개인회원 무료
        Cryopreservation of canine spermatozoa affords potential exchange of genetic material, and thus may lead to improvement in the breeding management. However, canine spermatozoa undergo many damages such as, cold shock, ice crystal formation, oxidative stress during cryopreservation. In this study used the CASA for investigating the effect of various trehalose concentrations and thawing temperatures on the sperm viability. In addition, the efficacy of the most optimal of the tested cryopreservation protocols in this study was verified by AI as the in vivo test. Also, this study evaluates the variation of frozen- thawed canine spermatozoa during different incubation condition. The addition of trehalose 25 mM was optimal concentration and frozen-thawed semen quality was significantly higher better than control (Glucose) and other concentration groups. In effect of thawing temperature on frozen-thawed sperm movement and intact acrosome evaluations, which result enhance the sperm motility and movement value depending on increase temperature condition at 36, 54 and 72℃. Also, in the effect of different incubation condition on frozen-thawed sperm after thawing at 36℃ for 60 sec, that the results trehalose 25 mM was significantly better (p<0.05) than glucose in general as well as, the post-thawed sperm motility and intact acrosome was reduced depending on increase the incubation time. Especially, incubation at 4 to 8 hour was rapidly depreciation of movement value and the rate of intact acrosome was dropped similar tendency. Thus, incubation 17℃ was better than other incubation groups on sperm motility and acrosome integrity. For the in vivo evaluate of spermatozoa survival and is the most definitive test of sperm function, we performed artificial insemination in estrous bitch. The semen was prepared for intrauterine insemination using the 25 mM trehalose freezing extender and thawing at 36℃, and 2 bitches were inseminated with 1×106 motile spermatozoa by surgical method. The results of AI, the pregnancy rates, mean litter size and oocyte fertilization rate were 16.6% (1/6), and 50% (2/4), respectively. In conclusion, based on the results of these experiments, the effect of addition of trehalose on extender improves the movement and intact acrosome of frozen-thawed semen. In particular, trehalose 25 mM groups was higher than other different concentration group on movement value and acrosome integrity of frozen-thawed sperm. Also, through incubation condition, this study identify the optimal incubation temperature after thawing was 17℃. Furthermore, the information will be contributed to develop the canine ART including AI, IVF and canine ICSI. * This research was supported by iPET (Grants 110056-3), Ministry for Food, Agriculture, Forestry and Fisheries, Republic of Korea.
        9.
        2011.10 구독 인증기관·개인회원 무료
        Cell transplantation therapy using adult stem cells has recently been identified as a potential treatment for spinal cord injury (SCI). But, recovery after traumatic SCI is very limited. As dogs are physiologically much more similar to human compared with other traditional mammalian models in disease presentation and clinical responses, a number of researches demonstrated canis familiaris is a suitable model for human diseases. This study investigated the effect of transplantation of canine Mesenchymal Stem Cells (cMSC) and neural-induced cMSC (nMSC) to understand how these cells improve neurological function in canine SCI model. The differentiation of cMSC into neural precursor cells was induced in dulbecco’s modified eagle’s medium supplemented with N2-supplement, dibutyryl cyclic adenosine monophosphate, and butylated hydroxyanisole. SCI was induced between T1 and T2 by surgical hemi-section in adult dogs, and then assigned to two groups according to the applied cell types (cMSC vs nMSC). Pelleted cMSC or nMSC were transplanted directly into the injured site after SCI, respectively. Analysis of motor function after transplantation was evaluated by modified Olby score. Magnetic resonance imaging (MRI), histological and immunohistichemical analysis were also performed. Functional recovery in group of cMSC was increasing gradually after transplantation and was higher than nMSC. In MRI, we could not confirm any difference between the cMSC and nMSC experimental groups. Immunohistochemically, beta3-tubuline and nestin were observed in injury site of two experimental groups with the expression level close to non-injured groups. Transplantation of mesenchymal stem cells could promote neuronal reconstruction and repair motor function in SCI. These showed mesenchymal stem cells could be a great candidate as a therapeutic tools in degeneration disease, and dogs could be used to explore human regenerative medicine as a promising animal model. This research was supported by iPET (Grants 110056032CG000), Ministry for Food, Agriculture, Forestry and Fisheries, Republic of Korea.
        10.
        2011.10 구독 인증기관·개인회원 무료
        Acteoside (verbascoside) is a typical phenylethanoid glycoside, extracted from various plants. It has various biological functions such as anti-oxidant, anti-inflammation, and anti-hypertension. Specially, it was powerful anti-oxidants either by direct scavenging of reactive oxygen and nitrogen species, or by acting as chain-breaking peroxyl radical scavengers. We examined the role of acteoside in IVM medium on the morphological progress of meiosis, developmental competence, and ROS in porcine oocytes. And we investigated effect of acteoside on the oocytes condition represented by cytoplasmic maturation by homogeneous distribution and formation of cytoplasmic organelles and regulation of apoptosis-related genes. The selected COCs were cultured in TCM-199 with various concentration of acteoside: 0 (control), 10, 30, and 50 μM. After 22 h of maturation with hormones, the oocytes were washed twice in a fresh maturation medium before being cultured in hormone-free medium for additional 22 h. The oocytes maturation rates of supplemented with acteoside were no significantly different compared with control group (71.13, 75.96, 72.95 and 73.68%, respectively). Level of ROS was significantly decreased in acteoside treated group. Furthermore, the parthenogenetic blastocyst rate was significantly improved in 10 μM acteoside treated group compared with control group (40.03 vs. 22.95%). During IVM, 10 μM acteoside treated oocytes showed that the mitochondria and lipid droplet were smaller and homogeneous distribution in cytoplasm compare with non-treated control oocytes. And reverse transcription polymerase chain reaction (RT-PCR) witarthenogenetic blstocysts revealed that acteoside increased the anti-apoptoticgenes, otherwise reibued pro-apoptotic genes. In conclusion, our results represents that addition of acteoside to the IVM medium has a beneficial effect in physiology of porcine oocytes such as viability and activation, providing a improved method for porcine oocytes in vitro.
        17.
        2005.12 구독 인증기관 무료, 개인회원 유료
        This study was carried out to evaluate the effects of washing medium, breed and washing temperature of fresh and frozen-thawed boar sperm on mitochondrial activity and membrane integrity by flow cytometry. More than 80% of fresh sperm washed with mTLP-PVA medium at 20℃ exhibited an intact membrane and a functional mitochondrion. With frozen-thawed samples, a large number of sperm showed both damaged membrane (36.4~46.9%) and nonfunctional mitochondrion (55.1~71.1%) in the mTLP-PVA and BTS washing media at 20℃. There were no breed effects of fresh and frozen-thawed sperm on mitochondrial activity and membrane integrity. The percentages of damaged membrane of fresh and frozen sperm, respectively, were higher at 4℃ washing temperature than at 20℃ washing temperature in the mTLP-PVA medium. We found that washing medium and washing temperature of fresh and frozen-thawed boar sperm were important for the analyses of mitochondrial activity and membrane integrity by flow cytometry.
        4,000원
        20.
        2011.12 KCI 등재 서비스 종료(열람 제한)
        An Intergenerational Horticultural Program in a rural community in Korea was tried out to enhance social interaction between elderly citizens and children, to promote the positive self-esteem of the elderly in a rural community, to change the attitude of children towards the elderly, and to create a rural community full of vitality. The clients were 20 elderly (60-80 years old) and 40 preschool children (6-7 years old). The activities in this program included seed of hope, round autumn garden, dish garden, in the vegetable patch, flower decoration for the Chuseok Festival, rainbow flower basket, heart card, fragrance of love, and a kimchi party. The results were a decrease in depression among the elderly from 44.0% to 33.7%. General satisfaction among the elderly was 100%. The desire to rejoin among the elderly was 100%. General satisfaction among the children was 100%. The desire to rejoin among the children was 93.5%.
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