• Journal of Embryo Transfer
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• v.13 no.1
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• pp.69-76
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• 1998

This study was carried out to establish an effective system for embryo transfer techniques by analyzing several factors affecting in-vivo embryo transfer in Korean cattle Embryos were transferred into a toral of 301 recipients. The results obtained in studies on the factors affecting pregnancy rate after embryo transfer by condition of transfer time were as follows ; 1. The pregnancy rate by the seasons of transferred fresh and frozen embryos were not different, but the pregnancy rate was slightly higher in summer(80.8%). 2. The pregnancy rate by the days of embryo transfer after estrus were not different when fresh embryos were transferred, but the pregnancy rate was highest at 8 days when frozen embryos were transferred(P<0.01, 40.0%). 3. The pregnancy rate at estrus synchronization was remarkably higher with PGF$_2$$\alpha$ treated than natural (P<0.05, 70.4%, 43.4%). 4. The pragnancy rate by the degree of estrus synchronization was best when the estrus was synchronized in both fresh and frozen embryos (83.3% and 29.7%, respectively), but the pregnancy rate was not different among $\pm$2 days. But the pregnancy rate of frozen embryos were slightly higher when the recipients exhibited estrus earlier than donors.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2004.10a
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• pp.117-117
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• 2004

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.5
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• pp.470-474
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• 2014

This study proposes an improved synchronization control scheme for a low-cost 400Hz power supply for a no-break power transfer system. In the case of aircraft applications, the 400Hz power supply called ground power units is accepted and used as the external electrical power system during stopovers on ground. A momentary break in the supply occurs when shifting from one power source to another. To allow shifting without a break in the supply, the two power sources are momentarily connected in parallel. The proposed synchronization control is achieved by connecting an existing synchronization bus to the voltage zero-crossing signal of a generator power with discrete logic ICs and analog circuits. Therefore, unlike expensive controllers, such as DSP and CAN, the proposed control scheme is rather simple and may decrease operational cost. The practical feasibility of the proposed control scheme is proven by experimental results.

• Journal of Embryo Transfer
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• v.27 no.2
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• pp.87-92
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• 2012

A study on estrus synchronized dairy cows using progesterone intravaginal device was done to classify each cow's reproductive status from calving to synchronization and to evaluate the reproductive performance according to ovarian and uterine status, and calving season. From calving to estrus synchronization, silent heat or error of estrus detection among ovarian status and endometritis among uterine disorders were exposed in the most distribution (75.4% and 48.3%, respectively). The pregnancy rate of cows with inactive ovaries was lower than those in the follicular and luteal phase. And according to the uterine status before estrus synchronization, the pregnancy rate was similar in three groups; normal, endometritis, and pyometra (70.9, 69.1 and 100%, respectively). The interval from calving to conception was shorter (p<0.05) in cows calved during autumn than in cows calved during spring and winter.

• Journal of Embryo Transfer
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• v.26 no.2
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• pp.91-96
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• 2011

The purpose of this study was to evaluate the effects of days open on subsequent reproductive performance following to estrus synchronization in the 114 lactating dairy cows. The animals were divided into two groups according to the time of estrus synchronization; viz, ${\leq}$ 85 days, and > 85 days postpartum, respectively. The estrus synchronization protocol consisted of insertion of a controlled internal drug release (CIDR) device containing 1.9 g progesterone with an injection of 250 ${\mu}g$ gonadorelin (Day 0), an injection of $PGF_2{\alpha}$ and removal of the device on Day 7, an injection of 250 ${\mu}g$ GnRH on Day 9, and TAI 17 h later. Pregnancy diagnosis was determined at 30 to 60 days after TAI using both ultrasonography and rectal palpation. The body condition score (BCS) gradually increased over the postpartum period. In estrus synchronized cows until 85 days, conception rate on first service, number of service per conception, interval from estrus synchronization to conception, and interval from calving to conception were not significantly different among two farms (P>0.05). In estrus synchronized cows after 85 days postpartum, conception rate on first service, number of service per conception and interval from calving to conception were significantly different ($P{\leq}0.05$) between herds A and B (26.8 vs 50.0%; $2.1{\pm}1.35$ vs $1.37{\pm}0.54$ times, $237.3{\pm}97.8$ vs $164.7{\pm}69.3$ days, respectively). In estrus synchronized cows after 85 days postpartum interval from estrus synchronization to conception was greater (P<0.01) in herd B than in herd A ($63.6{\pm}57.4$ vs $26.1{\pm}24.9$). These results indicate that the time of estrus synchronization for maximized the reproductive performance is before 85 days postpartum and feeding and management is important factor for high reproductive performance.

• IEMEK Journal of Embedded Systems and Applications
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• v.15 no.1
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• pp.17-23
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• 2020

We propose a system time synchronization method between embedded Linux-based distributed control devices by using Transmission Control Protocol (TCP) communication and General Purpose Input Output (GPIO) device. The GPIO signal is used as the trigger signal for synchronization and the TCP communication is used to transfer the system time of master Linux, which serves as the reference clock, to slave Linux. Precise synchronization performance is achieved by measuring and compensating for the propagation delay of GPIO signal and the acquisition and setting latency of Linux system time. We build an experimental setup consisting of two embedded Linux systems, and perform extensive experiments to verify the performance of the proposed synchronization method.

• Journal of Power Electronics
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• v.18 no.1
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• pp.251-265
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• 2018

To enable a master-slave control independent microgrid system (MSCIMGS) to supply electricity continuously, the microgrid inverter should perform mode transfer between grid-connected and islanding operations. Transient oscillations should be reduced during transfer to effectively conduct a seamless mode transfer. This study uses a typical MSCIMGS as an example and improves the mode transfer strategy in three aspects: (1) adopts a status-tracking algorithm to improve the switching strategy of the outer loop, (2) uses the voltage magnitude and phase pre-synchronization algorithm to reduce transient shock at the time of grid connection, and (3) applies the hybrid-sensitivity $H_{\infty}$ robust controller instead of the current inner loop to improve the robustness of the controller. Simulations and experiments show that the proposed strategy is more practical than the traditional proportional-derivative control mode transfer and effective in reducing voltage and current oscillations during the transfer period.

• Journal of Embryo Transfer
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• v.24 no.4
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• pp.271-274
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• 2009

To establish a protocol of estrus induction and synchronization in European mouflon, we performed artificial insemination using frozen-thawed semen and exogenous hormones. CIDR was inserted into vaginas of four mouflons for 16 days. A day before removal of CIDR, PG 600 was injected intramuscularly. $PGF_2{\alpha}$ was injected when removing CIDR. Artificial insemination was cervically conducted with injecting LHRH 48 hours after CIDR withdrawal. Even though no pregnancy was confirmed, estrous signs were notified like open cervix, congestion of vaginal wall and discharge of cervical mucus. Further research in the wild sheep would be needed for development of artificial breeding methods and advancing sustainability of domestic zoos.

• Journal of Animal Reproduction and Biotechnology
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• v.36 no.4
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• pp.247-252
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• 2021

Embryo transfer (ET) in the animal is an important procedure to generate genetically engineered animals and conserve genetic resources. For ET experiments in mice, pseudopregnant recipients are usually prepared with proestrus stage of females and vasectomized males. However, this conventional method is inefficient because the size of female colonies should be large to select only the proestrus stage in the estrous cycle and the surgical procedures are required to generate vasectomized males. In this study, we established a simple and efficient protocol to prepare ET recipients using the estrous synchronization with hormone injection and the mating with wild male mice. The delivery rate of ET recipients tended to be increased with estrous synchronization using hormone injection (100%) compared to the conventional method (71%). Further, natural pregnancy of the recipients, induced by mating with a wild male, significantly enhanced the birth rate of ET offspring than the conventional method (33% vs. 13%). Based on the results, we concluded that our new protocol using hormone injection to ET recipients and mating with wild males could be more efficient and simpler compared to the conventional method.

• Journal of Embryo Transfer
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• v.23 no.2
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• pp.109-114
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• 2008

This study examined pregnancy and fetal loss rates according to different estrus synchronization protocols and injection of gonadotropin releasing hormone (GnRH) after transfer of Korean Native Cattle embryos to Holstein recipients. In Experiment 1, recipients received no treatment (Control, n = 119); two injections of prostaglandin$F_{2{\alpha}}$ ($PGF_{2{\alpha}}$ ) 11 days apart (PGF group, n = 120); GnRH (day 0)-$PGF_{2{\alpha}}$ (day 7)-GnRH (day 9) (Ovsynch group, n = 120); and CIDR (day 0)-$PGF_{2{\alpha}}$ and CIDR removal (day 7)-GnRH (day 9) (CIDR group, n = 110). In Experiment 2, the control group was received no treatment of GnRH. The treatment groups were received GnRH at embryo transfer (ET) (day 0), 7 days later, 14 days later, ET and 7 days later, 7 and 14 days later, or ET, 7 and 14 days later. Recipients were assigned to treatment randomly and received two in vitro produced blastocysts. Pregnancy was diagnosed at day 60 by palpation per rectum. Fetal loss to term was determined by palpation every 90 days thereafter. In Experiment 1, the pregnancy rate in the CIDR group (59.1%) were higher than in the Control group (42.0%) (p<0.01); fetal loss rates were similar for all groups (12.0 to 18.5%). In Experiment 2, the pregnancy rate in Day 0+7+14 group was higher (60.2%) than the control (40.2%) (p<0.01) and resulted in a lower fetal loss (p<0.05) than the control (4.6 vs. 11.4%). There were no significant difference between other treatment and the control (p>0.05). These results show that pregnancy rates of bovine embryos can be enhanced by CIDR insertion or GnRH $3{\times}$ treatment. Additionally, fetal loss may be reduced with GnRH treatment after ET.