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압전 구동기와 레버 링키지를 이용한 6 자유도 스테이지의 비선형성 평가에 기초한 정밀 위치 제어기의 설계
문준희(Jun Hee Moon),이봉구(Bong-Gu Lee) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.10
Precision stages for 6-DOF positioning, actuated by PZT stacks, which are fed back by gap sensors and guided by flexure hinges, have enlarged their application territory in micro/nano manufacturing and measurement area. The precision stages inherently have such limitations as the nonlinearity between input and output in piezoelectric stacks, feedback signal noise in precision capacitive gap sensors and low material damping in precision kinematic linkages of mechanical flexures. To surmount these limitations, the precision stage is modeled with physics-based variables, which are identified by transient response correspondence, and a gain margin calculation algorithm using the Prandtl-Ishlinskii model and describing function is newly developed to assess system performance more precisely than linear controller design schemes. Based on such analyses, a precision positioning controller is designed. Excellent positioning accuracy with rapid settlement accomplished by the controller is shown in step responses of the closed-loop system.
회전체의 진동 측정과 분석을 통한 이상 진단 시스템 개발
문준희(Jun Hee Moon),강성범(Sung Bum Kang),박희재(Heui Jae Park) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
Rotating machinery's faults such as unbalanced mass, eccentricity, and bearing fracture make the characteristic features of vibration different from that of normal operating condition. Fault diagnosis of the rotating machinery is achieved by the following ways: Firstly, identify the system in normal condition with a linear model. Secondly, assess the stochastic characteristic of the system in order to define the threshold of abnormal condition and to design a digital filter appropriate for the system. Finally, diagnose the system fault by error difference evaluation and by STFT analysis. The developed algorithm is experimentally verified for a CD-ROM drive.
Canola Oil로부터 코코아버터와 유사한 Triacylglycerol 조성을 가진 재구성지질의 효소적 합성 최적화 연구
문준희(Jun-Hee Moon),이정희(Jeung-Hee Lee),신정아(Jung-Ah Shin),홍순택(Soon-Taek Hong),이기택(Ki-Teak Lee) 한국식품영양과학회 2011 한국식품영양과학회지 Vol.40 No.10
본 연구에서는 카놀라유(canola oil)를 이용하여 코코아버터 유사 재구성지질 합성의 최적조건을 연구하였다. 반응기질로는 카놀라유와 palmitic ethyl ester와 stearic ethyl ester를 이용하였으며, 효소는 Lipozyme TLIM을 사용하여 반응기질의 몰비율과 반응효소의 양, 반응시간을 독립변수로 하고, D-optimal 계획에 의한 반응표면분석에 따라 합성을 실시하였다. 반응을 통해 acyl-migration은 최소로 일어나며, POS 및 SOS, POP의 함량은 최대로 합성되는 조건을 최적화 조건으로 결정하였다. D-optimal 계획에 의한 반응 표면분석을 실행한 결과, sn-2 위치 지방산 조성의 변화를 일으키는 acyl-migration(Y<sub>1</sub>)은 최소로 일어나고 POS(Y<sub>2</sub>)와 SOS(Y<sub>3</sub>), POP(Y<sub>4</sub>)는 최대로 일어나는 조건은 기질의 몰 비율은 canola oil : palmitic ethyl ester : stearic ethyl ester=1:3:9이며, 반응효소의 양은 6%이고, 반응시간은 40 min이었다. 이와 같은 반응조건으로 합성된 재구성지질의 acylmigration(% of palmitic acid+rstearic acid, Y<sub>1</sub>)은 10.43%, POS(Y<sub>2</sub>)의 함량은 25.31%, SOS(Y<sub>3</sub>)는 19.79%, 그리고 POP(Y<sub>4</sub>)는 11.22%로 측정되었다. Synthesis conditions of cocoa butter equivalents were optimized using the response surface method (RSM) by interesterification of canola oil (Ca), palmitic ethyl ester (PEE), and stearic ethyl ester (StEE). The reaction was catalyzed by immobilized lipase (Lipozyme TLIM) from Thermomyces lanuginosa to produce structured lipids containing a composition of triacylglycerols similar to cocoa butter. Reaction conditions were optimized using D-optimal design with the three reaction factors of the substrate molar ratio of canola oil to palmitic ethyl ester and stearic ethyl ester (Ca : PEE : StEE=1:1:3, 1:1.66:5, 1:2:6, 1:2.33:7, 1:3:9, X<sub>1</sub>), enzyme ratio (2∼6%, X<sub>2</sub>), and reaction time (30∼270 min, X<sub>3</sub>). The optimal conditions that minimized acyl-migration while maximizing 1-palmitoyl-2-oleoyl-3-stearoyl glycerol (POS), 1,3-distearoyl-2-oleoyl glycerol (SOS), and 1,3-dipalmitoyl-2-oleoyl glycerol (POP) were predicted, resulting in Ca : PEE : StEE=1:3:9, 6% of enzyme ratio, and 40 min of reaction time. The reaction product of structured lipids was synthesized again under the same conditions, showing 10.43 area% of acyl-migration, 25.31 area% of POS/PSO, 19.79 area% of SOS, and 11.22 area% of POP.