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Controlled Drug Delivery: Transition to Nanosystems
권일근,박기남,Hatem Hegazy 한국생체재료학회 2006 생체재료학회지 Vol.10 No.3
Over the past few decades, drug delivery systems have advanced significantly to deliver novel drug entities, such as proteins and oligonucleotides, and a number of drug delivery technologies involving smart polymers have been developed. Polymers have been essential in the development of controlled release dosage forms, as they offer a wide range of physicochemical properties, such as aqueous solubility, biodegradability, and molecular weight. Furthermore, emergence of drug delivery techniques such as smart hydrogels, micelles, liposomes, and PEGylation has improved the bioavailability of poorly soluble drugs, protein therapeutics, and other drugs. New approaches in designing better drug delivery systems involve the use of nanotechnology to create polymer particles in the nano range and/or incorporate these nanoparticles into microdevices to allow better control of drug release and more efficient drug targeting.
차량용 블로우 모터 케이스 2축 굽힘 공정의 치수 정밀도 향상에 관한 연구
권일근,김국용,박준우 한국산업융합학회 2018 한국산업융합학회 논문집 Vol.21 No.6
In case high strength steels are applied for press-formed automotive parts, it is very difficult to secure forming accuracy due to large springback compared to moderate strength steels. In this study, a repetitive step-wise forming analyses based on secant method was proposed as the die design method for mandrel(bending tool) for the 2-axis bending equipments. A bending die with circular mandrel was designed for the DP780 blow motor case of which diameter and thickness are 70.8mm and 2.0mm respectively. Forming tests were performed to verify the validity of established die design and the results were compared with that of conventional HGI(Hot galvanized iron steel) blow motor case. For additional improvement in forming accuracy, an elliptical mandrel was proposed and its validity was verified using forming analyses based on secant method.
권일근,박홍석 한국정밀공학회 2011 International Journal of Precision Engineering and Vol. No.
Thrust shaft is one of the important components of the built-up type crankshaft for the large marine diesel engine. Conventionally, the thrust shaft has been produced by free forging process. The drawbacks of this method are the low dimensional accuracy and low productivity. In this study, a new die forging process making it possible to form the two flanges with single forging operation was devised by introducing the floating die concept. This innovative technology not only increases effectiveness of material usage but also save the time cost for forging operation and post-machining. Through the investigation of two proposed supporting methods including hydraulic force and die block for floating die using FEM simulations, the die design customized for actual application could be established. The forged product with target dimensions is obtained by applying an efficient strategy for determination of initial floating height. Finally, to verify the proposed die forging concept and simulation results, the scale-down model tests were carried out. The physical experimental results show that the strategy for determination of initial floating height and of the proposed forging process is valid.