고정밀 회전 및 축방향 이송을 위한 신개념 원통형 자기부상 스테이지

The KIPS Transactions:PartD, 2008

In spite of the various techniques on the testing of embedded software, operation failures of embedded systems such as robot or satellite applications, are occurred frequently. The critical reason of these failures is due to the fact that software is embedded into a target system with inherent faults. Therefore, in order to prevent the failure owing to such faults, it needs a technique to test the embedded software which operates in real environment. In this paper, we propose a testing technique, aspect-based On-the-Fly testing that is to test the functionality and performance at real operation time. Our proposed technique gives some benefits of real test of unexpected input conditions, prevention of software malfunction, and reusability of aspect components for the testing.

Journal of the Korean Society of Precision Engineering, 2013

In Projection Stereolithography Apparatus (PSLA), Digital Micromirror Device (DMD) and Liquid Crystal Display (LCD) are used as a beam pattern generator. The DMD shows high resolution, but it is mostly applied in micro stereolithography due to high cost and fabricable area. In LCD, the size of pattern beam is freely controlled due to various panel sizes. The LCD, however, has some limitations such as short life time by the high power light source, non-uniform light intensity of pattern beam and low transmittance of UV-light. To solve these problems in LCD-based PSLA, a Scanbeam-SLA with LCD of 19 inches and visible LED-array is developed. In this system, the light module works like a scanner for uniform illumination. The system configuration, working principle and fabrication examples are addressed in this study.

A paired many-to-many -disjoint path cover (-DPC for short) of a graph is a set of  disjoint paths joining  distinct source-sink pairs in which each vertex of the graph is covered by a path. A two-dimensional  ×  torus is a graph defined as the product of two cycles   and   of length  and  , respectively. In this paper, we deal with an  ×  bipartite torus, even   ≥ , with a single faulty vertex, and present a necessary and sufficient condition for the torus to have a paired many-to-many 2-DPC connecting given two source-sink pairs as follows: Out of the four sources and sinks, exactly one of them has the same color as the faulty vertex. 1. 서 론 상호 연결망(interconnection networks)에서 노드들 사이의 라우팅이나 선형 배열의 임베딩 등과 관련하여 다루는 중요한 문제 중의 하나는 노드가 서로소인 경로 (node-disjoint paths)를 찾는 것이다. 노드가 서로소인 경로는 노드들 사이에 효율적인 데이터 라우팅을 위한 병렬 경로로 사용될 수 있다. 또한 노드가 서로소인 경 로에서 각 경로는 파이프라인 계산에 이용될 수 있다. 상호연결망은 자주 그래프로 모델 되는데, 정점과 에지 는 각각 노드와 통신 링크에 대응한다. 이 논문에서는 노드가 서로소인 경로를 간단히 서로소인 경로라고 부 르기로 한다. 서로...

Transactions of the KSME C: Industrial Technology and Innovation, 2015

In this study, the finite element analysis was carried out to investigate dynamic characteristics of the AGF(Active Gurney Flap) which is under development for reducing vibration and noise of the helicopter rotor system. The Gurney flap is a kind of small flat plate, mounted normal to the lower surface of the airfoil near to the trailing edge. An electric motor, L-shaped linkages and flap parts were integrated into a rotor bade, and 3~5/rev control was given to the AGF to reduce the vibration in the fixed frame. Thus, an explicit time integration method was adopted to investigate the dynamic response of the AGF with considering both centrifugal force due to the rotor rotation and active control input, and it can be seen that the vertical displacement of the AGF was satisfied to meet the design requirement.

Transactions of the Korean Society of Mechanical Engineers A, 2010

Journal of the Korean Society for Aeronautical & Space Sciences, 2011

In this study, the aeroelastic analysis of rotorcraft in forward flight has been performed using dynamic inflow model to handle unsteady aerodynamics. The quasi-steady airload model based on the blade element method has been coupled with dynamic inflow model developed by Peters and He. The nonlinear steady response to periodic motion is obtained by integrating the full finite element equation in time through a coupled trim procedure with a vehicle trim for stability analysis. The aerodynamic and structural characteristics of dynamic inflow model are validated against other numerical analysis results by comparing induced inflow and blade tip deflections(flap, lag). In order to validate aeroelastic stability of dynamic inflow model, lag damping are also compared with those of linear inflow model.

Journal of the Society of Naval Architects of Korea, 2021

Korean coastal fishery suffers from profitability degradation due to a decrease in fisheries resources, pollution in coastal waters, fuel coast increase, and market opening for aquaculture products. The next generation Korean fishing vessel aims at the improvement of energy efficiency, enhancement of crew welfare, and safety. These purposes can be accomplished by adopting a new standard hull form with improved resistance performance and a modernized residence facility on the deck. In order to improve resistance performance, this study attempts to optimize design variables for stern flaps for three kinds of fishing vesselscoastal multipurpose , coastal trap, and dredged nets. A series of model tests for these fishing vessels was carried out in the towing tank of Pusan National University. The results indicate that for some cases, the stern flap caused the stern trim of the vessel to decrease, leading to the resistance reduction.

Journal of the Korean Society of Marine Engineering, 2010

In this paper, we propose a method for swing-up and stabilization of a SESIP(Self-Erecting Single Inverted Pendulum) system which is one of the typical nonlinear systems. We use PV(Proportional velocity) controller for swinging up the pendulum and employ a PI-type state-feedback controller for stabilizing the pendulum. Control is switched to a stabilizing controller, which is designed to balance the inverted position of pendulum and the cart position to the near vertical position. Computer simulations are performed to illustrate the control performance of the proposed scheme.

Journal of the Korean Society for Aeronautical & Space Sciences, 2012

Aerodynamic analysis(DATCOM) and radar cross section(RCS) analysis(POFACETS) were integrated for the air-to-surface missile concept design using a design framework. The missile geometry was defined based on the CAD(CATIA) for synchronizing the manufacturing with design processes. Aero/RCS analyses were linked with the CAD process under the ModelCenter framework in order to receive the geometry data automatically. The missile design baseline configuration was selected from ROC(requirement of capability). Then the RCS minimization was performed subject to thelargerthebetter constraint of the missile lift-to-drag ratio. This study demonstrated that various design strategies can be performed efficiently about many missile configurations using this design framework in the missile conceptual design phase.

Journal of the Korea institute for structural maintenance and inspection, 2013

Probabilistic nonlinear first ply failure loads of flat composite panels and nonlinear buckling loads of curved composite panels with cutouts are estimated to provide the more reliable main load carrying structure in the renewable energy industry and offshore structures. The response surface method approximates limit state surface to a second order polynomial form of random variables with the results of deterministic finite element analyses at given sampling design points. Furthermore, the iterative linear interpolation scheme is used to obtain a more accurate approximation of the limit state surface near the most probable failure point (MPFP). The advanced first order second moment method and the Monte Carlo method are performed on an approximated limit state surface to evaluate the probability of failure. Finally, the sensitivity of the reliability index with respect to transformed random variables is investigated to figure out the main random variables that have an effect on failures.