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임재곤(Jae-Gon Lim),김만달(Man-Dal Kim),범희락(Hee-Rak Beom),홍성욱(Seong-Wook Hong) 한국생산제조학회 2010 한국공작기계학회 추계학술대회논문집 Vol.2010 No.-
This paper presents a result of dynamic modeling and simulation for deploying beams. When a beam is axially deploying, lateral vibration is often observed. This paper proposes a finite element modeling technique to cope with time-varying properties of this kind of deploying beams. The simulated result from the proposed model is compared with that from a reference. Two-stage deploying beams are also investigated with the proposed dynamic modeling method.
위치결정 스테이지 베이스 진동 모델링 및 저감기법 개발
박아영,임재곤,홍성욱,Park, Ah-Yeong,Lim, Jae-Gon,Hong, Seong-Wook 한국생산제조학회 2010 한국생산제조학회지 Vol.25 No.6
Precise positioning stages are often employed for precise machinery. For the purpose of vibration isolation, these precise positioning stages are mounted on a heavy base structure which is supported by compliant springs. Then the base structure is subjected to residual vibration due to the reactive force and vertical moving load induced by the stage motion. This paper investigates the vibration behavior of a positioning stage base and the associated vibration suppression technique. A dynamic model is developed to investigate the base vibration due to the reactive force and moving load effects by the moving stage. An input shaping technique is also developed to suppress the residual vibrations in base structures. Simulations and experiments show that the developed dynamic model adequately represents the base vibration and that the proposed input shaping technique effectively removes the residual vibrations from the positioning stage base.
PP의 분자량 분포 및 충격보강제 종류에 따른 TPOs의 특성
이용희 ( Yong Hee Lee ),남병욱 ( Byeong Uk Nam ),임재곤 ( Jae Gon Lim ),홍채환 ( Chae Hwan Hong ) 한국공업화학회 2009 응용화학 Vol.13 No.1
In this work, we have tried to find out the important factors to affect the flowability and mechanical properties of Themoplastic olefins(TPOs). TPOs of our work were composed of Polypropylene(PP), impact modifier, Talc, and trace amount of additives. PPs were four types which were differnt Molecular weight distributions(MWD) and Melt indexes(MI). Also, impact modifiers were two types of Polyethylene copolymer elastomers and an appropriate Styrene ethylene butylene styrene block copolymer(SEBS) elastomer. In case of broad MWD PP, spiral flow length showed longer than that of higher MI PP in some cases. Namely, MWD parameter is more effective than MI parameter to improve the flowability in range of high shear rate. Also, we could find out SEBS used in this study improves the performance such as impact strength and flowability. of TPOs which can be widely used in automotive parts.
PDMS계 첨가제와 Grain pattern에 따른 PP Compound의 내스크래치성 연구
이용희 ( Yong Hee Lee ),남병욱 ( Byeong Uk Nam ),임재곤 ( Jae Gon Lim ),최치훈 ( Chi Joon Choi ) 한국고무학회 2008 엘라스토머 및 콤포지트 Vol.43 No.3
본 연구에서는 polypropylene 복합재료의 내스크래치성을 향상 시키기 위한 연구를 수행하였다. 내스크래치성 개선을 위하여 PP의 분자량이 다른 두 종류의 PDMS계 M/B를 제조하여 각각의 함량에 따른 기계적 물성과 내스크래치성을 평가 하였다. 더 좋은 물성을 보인 마스터배치를 선택하여 grain pattern에 따른 내스크래치성을 평가 하였다. UTM과 편광현미경을 통하여 기계적 물성과 스크래치성을 평가 하였다. Color 3D laser Scanning microscope로 표면 grain pattern 형상을 관찰하였다. 마스터배치의 분자량과 함량에 따른 기계적 물성의 차이는 비교적 적은것으로 평가 되었으며 내스크래치 평가에서는 고분자량의 M/B를 첨가함에 따라 내스크래치성이 향상 되는 것으로 나타났다. Grain pattern에 따른 스크래치 평가에서는 grain pattern이 깊이가 깊고 불규칙하며 그 형태도 크고, 둥근형일 때 내스크래치성이 우수한 것으로 나타났다. In this study, we have investigated mechanical properties and scratch resistance of polypropylene compounds by two types of masterbatch with different molecular weight of PP. Masterbatches were prepared with polypropylene(PP) and polydimethylsiloxane(PDMS) by melt mixing. Mechanical properties and scratch behavior were examined with UTM and polarizing microscope. The morphology surface of grain pattern was investigated Color 3D Laser Scanning Microscope. Mechanical properties of two masterbatches containing PP compounds showed a little bit difference in accordance with amount of M/B. Scratch resistance was much improved by adding masterbatches used high-molecular weight PP. Scratch resistance was excellent when grain pattern of the surface is deep, large, round and irregular.
흐름자국이 없는 PP 복합소재 제조를 위한 유변학적 특성 연구
이용희 ( Yong Hee Lee ),남병욱 ( Byeong Uk Nam ),임재곤 ( Jae Gon Lim ),최치훈 ( Chi Hoon Choi ) 한국고무학회 2009 엘라스토머 및 콤포지트 Vol.44 No.2
사출성형 시 흐름자국이 생기지 않는 흐름성이 향상된 PP(Polypropylene) 복합재료를 제조하기 위한 연구를 진행하였다. PP는 분자량 분포와 용융지수(MI)가 다른 4종류의 PP를 사용하였으며, PP, 탈크, 고무와 약간의 첨가제로 구성된 PP컴파운드의 유변학적 특성은 Spiral Flow(SF), MI, 전단점도를 측정함으로써 평가하였다. 분자량 분포가 넓은 PP를 사용한 경우 MI가 상대적으로 낮다 하더라도 SF는 MI가 높은 PP보다 높게 관찰되는 경우도 있었다. 사출성형시 표면에 흐름자국이 발생하지 않도록 하기 위해서는 분자량 분포가 넓은 PP를 사용하는 것이 바람직함을 확인하였다. Our objective is to increase the flowability of Polypropylene(PP) compounds and achieve flow mark free surface in injection molded specimen. We have investigated flowabilities of PP compounds which were composed of PP, rubber, talc, and trace amount of additives. Flowability measurement was performed with four types PPs of which molecular weight distributions(MWD) and melt indexes(MI) were different. Rheological properties of the PP compounding materials, such as spiral flow(SF) length, MI, and shear viscosity, were evaluated. When PP with the broad MWD was used, there were remarkable cases where the spiral flow length of low MI PP compound was longer than that of higher MI PP compound. The PP compound having low MI but broad MWD PP has more flowability than the compound with only high MI.