• 소성∙가공
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• 제31권3호
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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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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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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• 제30권7호
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• pp.733-738
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• 1997

순차적 양측 폐이식수술은 수술시 및 수술후 합병증이 매우 다양하며 수술후 결과가 매우 불량하다. 저자 등은 양측 폐 이식수술후의 혈역학적 변화를 연구관찰하고자 하였으며 수술후 발생할 수 있는 거부반 응을 예방하기 위하여 양측 폐재식수술을 선택,시행하였으며 폐동맥의 뒤틀림이나 협착, 좌심방내의 혈전발 생 등을 예방하기 위하여 폐동맥 및 좌심방 부위를 혈관감자로 폐쇄시킨 후 폐측 폐동맥의 전면을 절단하였고, 폐측 상하 폐정맥부위 좌심방 전면을 절단한 후 1시간동안 폐동맥 절단부위를 통해 PGEI이 함유된 I-C 용액을 주입하였고 1시간동안 I-C용액이 함유된 거즈를 이용하여 냉각을 유지하였다. 다시 5-0 prolene을 이 용하여 봉합하였다. 좌심방을 봉합할 때 내면이 외 전되게끔 everted suture 방법으로 봉합하였다. 주기관지는 완전 절단후 telescope방법으코 단단문합하였으며 폐재식 수술전후의 동맥혈 산소가스치, 대퇴동맥 및 폐동맥 압을 측정하여 비교하였으며 수술전후의 뚜렷한 혈역학적 변화는 없었다. 절단 결찰된 폐는 PcEl이 함유된 I-c용액을 폐동맥으로 4o cmHlo 압력으로 Is ~h입분의 속도로 총량이 70 mfg되도록 주입하\ulcorner으며 그후 1시간동안 냉각된 I-C용액이 함유된 거즈를 이용하여 절단된 폐를 감싸서 냉각저류보관하여 허혈성 손상을 예방함으로써 수술수기에 대한 합병증이 없는한 양측 폐 이식수술후 성 적은 양호할 것으로 생각된다.