• 한국항공우주학회지
• /
• 제44권10호
• /
• pp.895-903
• /
• 2016

우주용 영상센서의 비균일 출력특성 교정을 통한 영상품질향상을 목적으로 탑재교정장치가 요구된다. 탑재교정장치는 균일한 온도정보 제공을 위한 흑체를 비롯하여, 흑체로의 지향성 확보를 위하여 전개/수납 기능이 포함되는 교정 메커니즘으로 구성된다. 이 중, 교정 메커니즘은 궤도상에서 구동장치의 결함 발생 시 주광경로 확보를 위한 결함안전 기능이 요구된다. 추가적으로, 구동부에 대한 발사환경에서의 구조건전성 확보가 필수적이다. 본 논문에서는 단일장치로 발사환경 구속 및 결함안전 기능 구현이 가능한 전개수납형 교정 메커니즘을 제안하였다. 상기 제안한 메커니즘의 기능모델을 통한 동작 기능시험을 수행하여 설계의 유효성을 입증하였다.

• 한국항공우주학회지
• /
• 제39권7호
• /
• pp.682-687
• /
• 2011

일반적으로 탑재 교정을 위한 교정 반사경 구동장치는 교정임무 수행 시에는 주광경로 상의 전개위치로 반사경을 구동하며, 교정 후에는 주광경로와 이격된 수납위치로 반사경을 구동한다. 교정 반사경 구동장치의 결함 발생 시에는 반사경이 전개된 상태로 남아 주광경로를 차단하지 않도록 반사경을 강제 수납한다. 본 논문에서 제안한 결함 안전장치를 가지는 교정용 반사경 구동장치는 구동을 위한 스텝모터, 전개 및 수납 상태확인을 위한 마이크로 스위치, 베어링과 스프링의 기능을 동시에 갖는 피봇베어링 등으로 구성된다. 본 논문에서는 상기의 기능을 갖는 교정 반사경 구동장치 구현을 위한 구동장치 구성을 제안하였으며, 구성요소의 최적화 설계치를 도출하고 기능시험을 통해 결함안전 기능을 갖는 교정 반사경 구동장치의 유효성을 검증하였다.

• 한국지진공학회논문집
• /
• 제11권4호
• /
• pp.1-11
• /
• 2007

This paper verifies the difference of the seismic behavior and seismic damage of the neighboring two reinforced concrete piers damaged by the 1995 Hyogoken Nanbu earthquake. The two piers were almost the same size, carrying slightly different dead load, and were provided with the same reinforcement arrangement except the amount of longitudinal reinforcement at the bottom portion of the piers. The pier with more reinforcement was completely collapsed due to this near field earthquake by shear failure at the longitudinal reinforcement cut-off while the other was only damaged at the bottom by flexure even though the longitudinal reinforcement cut-off was also existed at the mid height of the pier. According to the results of the pseudo dynamic test, the seismic damage was recognized to be greatly dependent on the ground motion characteristics even though the employed ground motions had the same peak acceleration. The severe damage was observed when the test employed the seismic wave that had strong influence to the longer period range compared to the initial natural period of the pier. On the other hand, based on the similar model experiment, the defect of gas-pressure welded splice of longitudinal reinforcement was revealed to save the piers against collapse due to the so-called fail-safe mechanism contrary to the intuitive opinion of some researchers. It was concluded that the primary cause of the collapse of the pier was the extremely strong intensity and peculiar characteristics of the earthquake motion according to both the site-specific and the structure-specific effects.

• 한국철도학회논문집
• /
• 제10권6호
• /
• pp.709-716
• /
• 2007

철도차량의 주행안정성과 곡선추종성능을 동시에 획기적으로 개선하기 위한 능동조향대차의 가능성은 이론적으로는 계속적으로 검증되어 왔지만 능동제어를 위한 정보획득 문제, 부수적인 기계요소, 높은 에너지 소비, 고장에 대비한 안전기능 등과 같이 해결해야할 기술적 난제 때문에 많은 노력에도 불구하고 아직까지 상용화되지 못하고 있다. 이러한 문제점을 해결하고자, 본 논문에서는 보다 진보된 능동조향 메커니즘을 제안하고자 한다. 본 논문의 메커니즘을 이용하면 적은 제어력만 필요하기 때문에 기어와 같은 동력 전달장치가 필요 없고, 그 결과 추가되는 기계요소의 개수를 최소화 할 수 있으며 안전장치 또한 쉽게 구축이 가능하다. 본 논문에서는 제안된 능동조향대차의 개념에 관하여 소개하고 선형동적모델을 이용한 컴퓨터 모의실험을 통해 가능성을 검증하고자 한다.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2003년도 춘계 학술발표회논문집
• /
• pp.465-472
• /
• 2003

The main concept of base isolation system is to reduce the member forces by decreasing the earthquake forces transmitted to superstructure instead of the conventional techniques of strengthening the structural members. There are two important advantages in friction pendulum systems. The functions of carrying the vertical load and of providing horizontal stiffness are effectively separated. This results in a more stable system that eliminates the need of a fail-safe mechanism. Friction pendulum systems are less sensitive to variations in the frequency content of ground excitation and tend to limit the intensity of the farce imparted to the superstructure. This study investigates the friction coefficients on the FPS test specimens according to the velocity, bearing pressure and test waveform.

• 한국자동차공학회논문집
• /
• 제20권6호
• /
• pp.33-38
• /
• 2012

EMB is considered as the next generation braking mechanism because it has simple structure and is environment friendly. However, as other brake mechanisms, EMB should be operated reliably for any operating conditions. EMB should be designed with fail-safe and fault-tolerant control concepts which require robust fault detection algorithms for various possible faults. In the design of fault detection algorithms, it is very difficult to construct faulty conditions in real EMB and thus, simulations are often used to emulate the faulty conditions. In this paper, a simulation tool is developed using the commercial software to emulate gear faults in the EMB mechanism. A backlash compensation algorithm is introduced based on contact point detection because screw backlash causes a delay in clamping force response time.

• Earthquakes and Structures
• /
• 제8권5호
• /
• pp.1215-1240
• /
• 2015

In this paper, the Theory of Plastic Mechanism Control (TPMC) is applied to the seismic design of dual systems composed by moment-resisting frames and Chevron braced frames. The application of TPMC is aimed at the design of dual systems able to guarantee, under seismic horizontal forces, the development of a collapse mechanism of global type. This design goal is of primary importance in seismic design of structures, because partial failure modes and soft-storey mechanisms have to be absolutely prevented due to the worsening of the energy dissipation capacity of structures and the resulting increase of the probability of failure during severe ground motions. With reference to the examined structural typology, diagonal and beam sections are assumed to be known quantities, because they are, respectively, designed to withstand the whole seismic actions and to withstand vertical loads and the net downward force resulting from the unbalanced axial forces acting in the diagonals. Conversely column sections are designed to assure the yielding of all the beam ends of moment-frames and the yielding and the buckling of tensile and compressed diagonals of the V-Braced part, respectively. In this work, a detailed designed example dealing with the application of TPMC to moment frame-chevron brace dual systems is provided with reference to an eight storey scheme and the design procedure is validated by means of non-linear static analyses aimed to check the actual pattern of yielding. The results of push-over analyses are compared with those obtained for the dual system designed according to Eurocode 8 provisions.