• Transactions of Materials Processing
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• v.31 no.3
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• pp.124-128
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• 2022

NdFeB magnets have been positioned as the core materials in advanced technologies such as MRI (magnetic resonance imaging), FA (factory automation system), robot, motors, and so on based on the highest magnetic properties. To effectively improve the refined microstructure, the plastic deformation has been known as the good alternatives by the recrystallization. However, it has been regarded as being impossible because of the few slip systems in the RE-Fe-B magnets at room temperature. The purpose of this study was to investigate the possibility of control of grain refinement and magnetic anisotropy of NdFeB alloy powder by the severe plastic deformation. The NdFeB magnet powder was fabricated by gas atomization process, and the powder was pre-compacted at high temperature. The pre-compacted billets were deformed by HPT (high pressure torsion), and then the deformed billets were observed microstructure and magnetic properties. After the HPT process at room temperature, the grain size decreased with increasing because of the melted Nd-rich phase, and the anisotropy of Nd₂Fe₁₄B phase was formed after the HPT process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.131-136
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• 2004

The limited slip differential(LSD) is a device which enables the driving force to be transmitted from one slipping wheel to another wheel in such case that the car is stuck in clay or snow. When the unwanted slipping occurs on one wheel, the LSD temporarily restraints the differential motion to transmit the driving force in the other wheel. So far, many types of LSD were developed such as mechanical lock type, disk clutch type, viscous coupling type, torsion type and multiple clutch type. However these types of LSD is too complicated and expensive, so it is used only for 4WD outdoor vehicles, military vehicles, and a portion of deluxe car. So, many studies has been devoted to improve new types of LSD to cover those demerits of existing LSDs that the hydraulic LSD is developed as arepresentative result of that. The hydraulic LSD which uses the principle of gear pump is packed with viscous oil in tight container. When a slip occurs on one wheel, the hydraulic LSD generates torque caused by high oil pressure in the container. This study has been devoted to suggest an improved hydraulic LSD. In order to achieve it, we designed a new type of hydraulic LSD, produced it and did a rig test with it on real vehicle. From the rig test, it has been confirmed that the new type of hydraulic LSD can be directly applied to exiting vehicles without changing the design criteria

• Journal of Chest Surgery
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• v.30 no.7
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• pp.733-738
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• 1997

Sequential bilateral lung transplantation may result in a variety of perioperative and postoperative complications, showing high perioperative morbidity and mortality rates. This research was performed to investigate the hemodynamic changes in adult mongrel dogs after bilateral reimplantation, two methods preferred for avoiding or minimizing graft rejection. The anterior portion of the pulmonary artery and the left atrium proximal to the superior and the inferior pulmonary veins were resected out and then re-anastomosed one hour later to prevent torsion or stenosis of the anastomotic site and the formation of a thrombosis in the left atrium. An everted suture technique was employed for the left atrium; An hour after the division, however, the main bronchus was tightly anastomose by interrupted sutures of No. 4-0 prolene in a telescope method. A modified I-C solution mixed with PGEI was infused into the cut portion of the pulmonary artery at the rate of 15 mllkglmin and at a pressure of 40 cmH20 for a total dosage of 70 mlfkg in order to preserve the transected lung. Topical cooling using wet gauzes soaked with cold I-C solution was performed for one hour to prevent ischemic lung injury. The above procedures are considered to be beneficial for achieving a satisfactory outcome for bilateral lung reimplantation.