• Journal of Embryo Transfer
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• v.32 no.3
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• pp.183-192
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• 2017

The mammary gland tumor (MGT) is the most common neoplasia in intact female dogs. Of these, 50% are malignant and metastasis to the other sites are often occurred. Therefore, it is very important for decision of treatment plan and prognosis to differentiate benign tumor from malignancies. Calcification of MGT is a very important imaging finding. The purpose of this study was to investigate the radiological and computed tomographic images of the MGT and the morphology and distribution of calcifications in the MGT using the Breast Imaging Reporting and Data System classification. A total of 42 dogs with MGT were included in this study. The dogs were divided into two groups into benign and malignant groups based upon histologic or cytologic results. The appearance of calcification in the tumor on radiographs and CT images was analyzed for the HU value of pre- and post-contrast injection, margin, surface, and shape of the tumor and the lymph node abnormalities. On radiographs, the positive predictive value of malignant and benign tumors was 72.72 and 85.71%, respectively. On CT examinations, the positive predictive value of malignant and benign tumors was the same value of 83.33%. The maximum diameter of the tumor and the presence of abnormal lymph nodes on CT images showed a strong correlation with malignancies. Therefore, it is thought that radiographs and CT provide useful information for evaluating MGT in dogs.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.2
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• pp.1-10
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• 2018

This study investigated the acoustic forcing effects on the liquid column breakup length and the trajectory of liquid jets in crossflows. Cold-flow tests with a single hole circular nozzle injector were carried out by changing the injection pressure and acoustic forcing amplitude. Additionally, spray images were obtained at 12 phase angles to investigate the influence of the phage angle. The results revealed that the liquid column breakup lengths generally decreased under the acoustic forcing conditions, in comparison to those under the non-acoustic forcing conditions. However, they were not affected by the variation in the phase angles. On the contrary, it was found that the acoustic forcing hardly influenced the liquid column trajectories.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.1-2
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• 2011

Hybrid rockets have lately attracted attention as a strong candidate of small, low cost, safe and reliable launch vehicles. A significant topic is that the first commercially sponsored space ship, SpaceShipOne vehicle chose a hybrid rocket. The main factors for the choice were safety of operation, system cost, quick turnaround, and thrust termination. In Japan, five universities including Hokkaido University and three private companies organized "Hybrid Rocket Research Group" from 1998 to 2002. Their main purpose was to downsize the cost and scale of rocket experiments. In 2002, UNISEC (University Space Engineering Consortium) and HASTIC (Hokkaido Aerospace Science and Technology Incubation Center) took over the educational and R&D rocket activities respectively and the research group dissolved. In 2008, JAXA/ISAS and eleven universities formed "Hybrid Rocket Research Working Group" as a subcommittee of the Steering Committee for Space Engineering in ISAS. Their goal is to demonstrate technical feasibility of lowcost and high frequency launches of nano/micro satellites into sun-synchronous orbits. Hybrid rockets use a combination of solid and liquid propellants. Usually the fuel is in a solid phase. A serious problem of hybrid rockets is the low regression rate of the solid fuel. In single port hybrids the low regression rate below 1 mm/s causes large L/D exceeding a hundred and small fuel loading ratio falling below 0.3. Multi-port hybrids are a typical solution to solve this problem. However, this solution is not the mainstream in Japan. Another approach is to use high regression rate fuels. For example, a fuel regression rate of 4 mm/s decreases L/D to around 10 and increases the loading ratio to around 0.75. Liquefying fuels such as paraffins are strong candidates for high regression fuels and subject of active research in Japan too. Nakagawa et al. in Tokai University employed EVA (Ethylene Vinyl Acetate) to modify viscosity of paraffin based fuels and investigated the effect of viscosity on regression rates. Wada et al. in Akita University employed LTP (Low melting ThermoPlastic) as another candidate of liquefying fuels and demonstrated high regression rates comparable to paraffin fuels. Hori et al. in JAXA/ISAS employed glycidylazide-poly(ethylene glycol) (GAP-PEG) copolymers as high regression rate fuels and modified the combustion characteristics by changing the PEG mixing ratio. Regression rate improvement by changing internal ballistics is another stream of research. The author proposed a new fuel configuration named "CAMUI" in 1998. CAMUI comes from an abbreviation of "cascaded multistage impinging-jet" meaning the distinctive flow field. A CAMUI type fuel grain consists of several cylindrical fuel blocks with two ports in axial direction. The port alignment shifts 90 degrees with each other to make jets out of ports impinge on the upstream end face of the downstream fuel block, resulting in intense heat transfer to the fuel. Yuasa et al. in Tokyo Metropolitan University employed swirling injection method and improved regression rates more than three times higher. However, regression rate distribution along the axis is not uniform due to the decay of the swirl strength. Aso et al. in Kyushu University employed multi-swirl injection to solve this problem. Combinations of swirling injection and paraffin based fuel have been tried and some results show very high regression rates exceeding ten times of conventional one. High fuel regression rates by new fuel, new internal ballistics, or combination of them require faster fuel-oxidizer mixing to maintain combustion efficiency. Nakagawa et al. succeeded to improve combustion efficiency of a paraffin-based fuel from 77% to 96% by a baffle plate. Another effective approach some researchers are trying is to use an aft-chamber to increase residence time. Better understanding of the new flow fields is necessary to reveal basic mechanisms of regression enhancement. Yuasa et al. visualized the combustion field in a swirling injection type motor. Nakagawa et al. observed boundary layer combustion of wax-based fuels. To understand detailed flow structures in swirling flow type hybrids, Sawada et al. (Tohoku Univ.), Teramoto et al. (Univ. of Tokyo), Shimada et al. (ISAS), and Tsuboi et al. (Kyushu Inst. Tech.) are trying to simulate the flow field numerically. Main challenges are turbulent reaction, stiffness due to low Mach number flow, fuel regression model, and other non-steady phenomena. Oshima et al. in Hokkaido University simulated CAMUI type flow fields and discussed correspondence relation between regression distribution of a burning surface and the vortex structure over the surface.

• Korean Journal of Construction Engineering and Management
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• v.21 no.6
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• pp.95-102
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• 2020

The number of use cases in machinery, aviation, and other industries that manufacture precise parts is increasing, and the construction industry is also increasingly using 3D printing technology. Although various materials for 3D printing are currently being developed and utilized, 3D printing manufacturing has a problem that the mechanical properties of the product may change when compared with conventional manufacturing methods such as injection and molding. This paper verifies the effect of the printing orientation on the mechanical properties of the product in the manufacture of PA12 material and providing basic data on the practical use of the materials as building subsidiary materials and structural materials. The results of the experiment showed that the product printed in the orientation of 0° showed the lowest overall strength and elongation rate, and the product printed in the orientation of 45° showed the highest figure. Overall, tensile strength and yield strength increased between 0° and 45°, and tended to decrease somewhat at 45° to 90°.

• Journal of Embryo Transfer
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• v.33 no.3
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• pp.149-157
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• 2018

The objective of this study was to evaluate the effect of treating dairy cattle with exogenous human chorionic gonadotrophin (hCG), five (5) days post artificial insemination (AI) on serum progesterone (P4) concentration and pregnancy rate. In this experiment, five days after AI, cows were assigned randomly to two groups namely: a) treated group (67) which were administrered with 1500 IU hCG (Chorulon) and b) control group (61), which received no treatment. On day 5, 10, 15 and 20 after the artificial insemination, blood samples from a total of 8 cows (4 from each group) were collected and were analyzed for serum P4 concentration. Cows were detected for estrus according to standing heat by visual observation. Cows that were detected still in estrus after days 18-24 were re-inseminated and recorded as not pregnant (open). Pregnancy diagnosis was conducted by ultrasonographic examination and transrectal palpation of the uterus on approximately 60 days in cows that observed to be not in estrus. The conception rate in hCG treated and control groups were 52.5 and 36.1%, respectively. The results proved that there were no significant differences in conception rate between two groups (p=0.0568). However, pregnancy rates were reduced by hCG treatment. Average serum P4 concentrations did not differ between Hcg-treated and control groups on day 5 (0.377 versus 0.375 ng/ml). On day 20 serum P4 concentrations were greater in the treated group compared with the control group (3.085 versus 2.010 ng/ml). The treatment with hCG seemed to increase P4 level compared with the control. In conclusion, the results of this study showed that 1500 IU of hCG administered on 5 day post AI increased conception rate in dairy cows. This was supported by the results on serum P4 concentration which was greater in hCG treated group.

• Journal of Embryo Transfer
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• v.28 no.2
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• pp.157-162
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• 2013

Methoxychlor (MXC) was developed to be a replacement for the banned pesticide DDT. HPTE [2,2-bis (p-hydroxyphenyl)-1,1,1-trichloroethane], which is an in vivo metabolite of MXC, has strong oestrogenic and anti-androgenic effects. MXC and HPTE are thought to produce potentially adverse effects by acting through oestrogen and androgen receptors. Of the two, HPTE binds to sex-steroid receptors with greater affinity, and it inhibits testosterone biosynthesis in Leydig cells by inhibiting cholesterol side-chain cleavage enzyme activity and cholesterol utilisation. In a previous study, MXC was shown to induce Leydig cell apoptosis by decreasing testosterone concentrations. I focused on the effects of MXC on male mice that resulted from interactions with sex-steroid hormone receptors. Sex-steroid hormones affect other organs including the kidney and liver. Accordingly, I hypothesised that MXC can act through sex-steroid receptors to produce adverse effects on the testis, kidney and liver, and I designed our experiments to confirm the different effects of MXC exposure on the male reproductive system, kidney and liver. In these experiments, I used pre-pubescent ICR mice; the puberty period in ICR mice is from postnatal day (PND) 45 to PND60. I treated the experimental group with 0, 100, 200, 400 mg MXC/kg b.w. delivered by an intra-peritoneal injection with sesame oil used as vehicle for 4 weeks. At the end of the experiment, the mice were sacrificed under anaesthesia. The testes and accessory reproductive organs were collected, weighed and prepared for histological investigation. I performed a chemiluminescence immune assay to observe the serum levels of testosterone, LH and FSH. Blood biochemical determination was also performed to check for other effects. There were no significant differences in our histological observations or relative organ weights. Serum testosterone levels were decreased in a dose-dependent manner; a greater dose resulted in the production of less testosterone. Compared to the control group, testosterone concentrations differed in the 200 and 400 mg/kg dosage groups. In conclusion, I observed markedly negative effects of MXC exposure on testosterone concentrations in pre-pubescent male mice. From our biochemical determinations, I observed some changes that indicate renal and hepatic failure. Together, these data suggest that MXC produces adverse effects on the reproductive system, kidney and liver.

• Journal of Embryo Transfer
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• v.28 no.3
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• pp.185-191
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• 2013

The purpose of this study is to improve production efficiency of vitrified-thawed transgenic bovine embryos. Transgenic bovine embryos were produced by injection of FIV-GFP lentiviral vector into perivitelline space of in vitro matured MII stage oocytes, and then in vitro fertilization. EGFP-expressing transgenic bovine blastocysts were cultured in serum-containing and serum-free medium. These blsatocysts were vitrified by pull and cut (PNC) container made with 0.25 cm plastic straw. Results indicate that total developmental rates of normal IVF embryo cultured in serum-containing and-free medium into blastocyst were not significantly different (22.3 vs 21.5%) and those of GFP-expressing transgenic bovine embryo into blastocyst showed no significant difference between serum-containing (13.9%) and-free medium (13.1%). However, developmental rate of GFP transgenic embryo was significantly (P<0.05) lower than its of normal IVF embryos. In additional study, we vitrified GFP transgenic normal bovine blastocysts using PNC vitrification method. Survival rate of vitrified-thawed GFP transgenic blastocyst (23.1%) was significantly (P<0.05) lower than its of normal blastocysts (68.9%). Although, survival rate of vitrified-thawed GFP transgenic blastocyst was lower than its of normal blastocyst, our result may suggested that PNC vitrification method is feasible to cryopreserve transgenic embryos. Our next plan will be the production of GFP express transgenic bovine derived from vitrified-thawed embryos using PNC method.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1375-1381
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• 2011

Combustion processes in an optically-accessible single-cylinder heavy-duty diesel engine equipped with a highpressure common-rail injection system were investigated for JP-8 and diesel. Direct imaging and two-color thermometry were employed to verify the emission trend for both fuels. The combustion process was characterized by image analysis with focus on luminosity. The results of two-color thermometry were analyzed on the basis of the flame temperature and KL factor distribution. Analysis of the combustion process by direct imaging showed that the ignition delay was longer for JP-8 than for diesel, while the flame was extinguished rapidly. Analysis of the flame luminosity showed that the combustion intensity was higher for diesel and that the flame lasted for a longer duration in this case. Two-color thermometry results showed that the high-temperature region extended over a large area during JP-8 combustion, implying the formation of a large amount of $NO_x$. In addition, the KL factor showed low level over a large area and relatively homogeneous in the case of JP-8 combustion, which implied that less smoke was produced when using this fuel.

• Journal of Embryo Transfer
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• v.27 no.4
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• pp.229-235
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• 2012

This research was investigated the relationship, in high-producing Holstein donor cows, between the number of the transferable embryos and the blood serum concentrations of Blood Urea Nitrogen (BUN), glucose and cholesterol, which affect the nutritional state of cows. CIDRs were inserted into the vaginas of twenty two heads of Holstein cows, regardless of estrous cycle. Superovulation was induced using folliclar stimulating hormone (FSH). For artificial insemination, donor cows were injected with $PGF_{2{\alpha}}$ and estrus was checked about 48 hours after the injection. Then they were treated with 4 straws of semen 3 times, with 12-hour intervals. Embryos were collected by a non-surgical method 7 days after the first artificial insemination. The total numbers of ova collected from 3 experimental groups whose blood BUN concentrations were <10 mg/dl, 11~18 mg/dl and ${\geq}19$ mg/dl were 8.9, 12.5 and 19.0, respectively; whereas the numbers of transferable embryos were 5.8 + 1.9, 7.9 + 2.8 and 5.2 + 1.4, respectively. When glucose concentration was <60 mg/dl, the total number of collected ova was 9.9, which was smaller than when the concentration was 60~70 mg/dl or ${\geq}70$ mg/dl. When glucose concentration was 60~70 mg/dl, the number of transferable embryos was 7.1 + 2.4, which was slightly larger than the numbers 6.4 + 2.1 and 6.1 + 1.7 that were obtained when the concentrations were <60 mg/dl and ${\geq}70$ mg/dl, respectively ; however, the differences were not significant (p>0.05). When cholesterol concentrations were <150 mg/dl, 150~200 mg/dl and ${\geq}200$ mg/dl, the total numbers of collected ova were 11.2, 11.3 and 8.6, respectively. Whereas the numbers of transferable embryos were 7.1 + 2.1, 7.3 + 1.9 and 5.6 + 1.3, respectively ; however, the differences were again not significant (p>0.05). The result of this research showed no significant difference in ovum recovery rate and the number of transferable embryos according to major metabolite concentrations in high-producing Holstein donor cows. However, it is considered that the failure of maintaining proper nutritional status would cause the fall in in vivo embryo productivity.

• Journal of Embryo Transfer
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• v.27 no.4
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• pp.237-243
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• 2012

This research was investigated the relationship between the number of the transferable embryos and estrus expression rate, BCS (Body Condition Score), which affect the nutritional state of the cow, in Holstein donor cows. CIDRs were inserted into the vaginas of twenty two head of Holstein cows, regardless of estrous cycle. Superovulation was induced using folliclar stimulating hormone (FSH). For artificial insemination, donor cows were injected with $PGF_{2{\alpha}}$ and estrus was checked about 48 hours after the injection. Then they were treated with 4 straws of semen 3 times, with 12-hour intervals. Embryos were collected by a non-surgical method 7 days after the first artificial insemination. When BCS was $$\leq_-$$2.5, the total number of collected ova was 7.3 + 1.9, which is significantly lower (p<0.05) than the numbers 15.4 + 2.8 and 15.4 + 2.1 that were obtained when BCSs were 2.75 and $$\geq_-$$3.0, respectively. Whereas the numbers of transferable embryos were 5.2 + 1.4 when BCS was $$\leq_-$$2.5, which was smaller than the numbers 6.0 + 2.1 and 8.5 + 1.8 that were obtained when BCSs were 2.75 and $$\geq_-$$3.0, respectively; however, the differences were not significant. As for estrus induction rate, the cow groups whose BCSs were 2.75 and $$\geq_-$$3.0 showed 100.0% and 95.0%, respectively. Whereas the cow group whose BCS was $$\leq_-$$2.5 showed 57.1%, and the differences were significant (p< 0.05). As for estrous expression rate, the cow groups whose BCSs were $$\leq_-$$2.5, 2.75 and $$\geq_-$$3.0 showed 100.0%, 100.0% and 85.7%, respectively; however, the differences were not significant. According to the result of this research, it is considered that the total number of collected ova and the number of transferable embryos will be affected by the nutritional state before and after in vivo embryo production and superovulation treatment, and that although the mechanism is not clear, poor stockbreeding management and nutritional level would cause the decrease of ovum recovery rate and the number of transferable embryos in high-producing cows. On the other hand, diverse researches on the superovulation treatment method that is suitable for high-producing Holstein donor cows would contribute to preventing ovarian cyclicity disorder, as well as to the early multiplication of cows with superior genes by increasing the utilization value of donor cows.