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LIPCA 작동기로 구동되는 날갯짓 기구의 설계 및 성능평가
이승식(Seungsik Lee),모 시아푸딘(Moh. Syaifuddin),박훈철(Hoon Cheol Park),윤광준(Kwang Joon Yoon),구남서(Nam Seo Goo) 한국항공우주학회 2005 韓國航空宇宙學會誌 Vol.33 No.12
본 논문에서 LIPCA(Lightweight Piezoceramic Composite Actuator)를 이용한 날갯짓(flapping) 기구의 개발에 관한 최근의 연구진척 사항을 제시하였다. 날갯짓 기구는 여러개의 연결막대를 이용하여 LIPCA의 제한된 작동변위를 커다란 날갯짓 각(flapping angle)이 발생하도록 증폭시켰으며, 패더링 메커니즘(feathering mechanism)을 적용하여 날갯짓과 동시에 날개에 비틀림이 발생하도록 설계되었다. 이 날갯짓 기구의 고유 날갯짓 주파수는 약 9㎐로, 이때 최대의 날갯짓 각이 발생하였다. 제작된 날갯짓 기구의 작동성능을 평가하기 위하여 날갯짓 주파수를 4㎐에서 15㎐까지 변화시키면서 발생되는 양력과 추력을 측정하였으며, 최대 양력과 최대 추력은 고유 날갯짓 주파수 부근에서 계측되었다. In this paper, we present our recent progress in the LIPCA (Lightweight Piezo-Composite Actuator) application for actuation of a flapping wing device. The flapping device uses linkage system that can amplify the actuation displacement of LIPCA. The feathering mechanism is also designed and implemented such that the wing can rotate during flapping. The natural flapping-frequency of the device was about 9 ㎐, where the maximum flapping angle was achieved. The flapping test under 4 ㎐ to 15 ㎐ flapping frequency was performed to investigate the flapping performance by measuring the produced lift and thrust. Maximum Lift and thrust were produced when the flapping device was actuated at about the natural flapping-frequency.
이승식(Lee Seungsik) 대한토목학회 2006 대한토목학회논문집 A Vol.26 No.1A
일축대칭의 단면특성을 갖는 T형 부재는 단변의 특성상 축방향 압축력으로 인하여 전체좌굴이 발생할 경우 휨-비틀림 좌굴이 지배모드가 된다. 인발성형 T형 부재의 휨-비틀림 좌굴거동을 실험적 연구를 통하여 알아보았다. E-glass/vinylester와 E-glass/polyester로 만들어진 2종류의 인발성형 부재가 사용되었으며, 보강층의 배치, 보강층의 두께, 구성물질의 부피비, 역학적 성질 등을 실험적으로 규명하였다. 좌굴실험에서 휨 및 비틀림에 대한 단순지지 조건을 만족시키기 위해서 knife edge를 시용하였으며, 3개의 potentiometer를 시용하여 실험체의 횡변위와 비틀림각을 측정하였다. 모든 실험체에 휨-비틀림 좌굴이 발행하였으며, 대부분의 실험체가 후좌굴 강도를 가지고 있음을 알 수 있었다. Due to single symmetry of cross section, T-shaped members are likely to buckle in a flexural-torsional mode when they are subjected to axial compression. Therefore, the flexural-torsional buckling can be regarded as a governing mode of global buckling. An experimental program has been carried out to investigate the flexural-torsional buckling behavior of pultruded T-shaped members. Two types of pultruded members were tested in the experiment, and they were made of either E-glass/viny-lester or E-glass/polyester. Lay-up and thickness of reinforcing layers, volume fractions of each constituents in layers, mechanical properties were experimentally determined. Two sets of knife edge fixure were used to simulate simple support condition for flexure and twisting, and the lateral displacements and the angle of twist were measured using three potentiometers. Every specimen buckled in a flexural-torsional mode, and most of the specimens showed post-buckling strength.
박소영(Park, So-Young),최훈(Choi, Hoon),이승식(Lee, Seungsik),박훈(Park, Hoon),윤순종(Yoon, Soon-Jong) 한국구조물진단유지관리학회 2009 한국구조물진단학회 학술발표회논문집 Vol.2009 No.2
Recently the demand of demolition for the unnecessary cylindrical silo structure is increasing due to the deterioration and malfunctional conditions and the issue of demolition is becoming a major highlight. This study present the pre-weakening of explosive demolition of the cylindrical silo structure by felling method. Pre-weakening for the blast demolition of the structure is usually conducted by the field experience in order to absent standard of pre-weakening. Design of pre-weakening extent and safety in a pre-weakened structure are discussed briefly as a part of the continuous research.
박소영 ( Park So-young ),최훈 ( Choi Hoon ),이승식 ( Lee Seungsik ),박훈 ( Park Hoon ),윤순종 ( Yoon Soon-jong ) 한국구조물진단유지관리공학회 2009 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.13 No.2
Recently the demand of demolition for the unnecessary cylindrical silo structure is increasing due to the deterioration and malfunctional conditions and the issue of demolition is becoming a major highlight. This study present the pre-weakening of explosive demolition of the cylindrical silo structure by felling method Pre-weakening for the blast demolition of the structure is usually conducted by the field experience in order to absent standard of pre-weakening. Design of pre-weakening extent and safety in a pre-weakened structure are discussed briefly as a part of the continuous research.