• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.41-42
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• 2011

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2001년도 춘계학술발표대회 개요집
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• pp.55-58
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• 2001

• 대한기계학회논문집
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• 제16권4호
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• pp.658-666
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• 1992

본 연구에서는 고속, 연속장업으로 이루어지고 있는 스템핑 공정에서 금형과 강판간의 접촉-슬립에 따른 마찰 및 윤활특성의 성능을 평가할 수 있도록 한 원형단면 형상의 드로오비드 마찰실험장치를 활용하여 가압력, 윤활유 특성, 드로잉 속도와 강 판의 표면특성 등에 따른 자동차용 냉연강판과 도금강판의 마찰계수와 드로오비드 저 항력에 대한 테이터 베이스를 구축하고자 한다.

• 한국항공우주학회지
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• 제44권3호
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• pp.274-280
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• 2016

2015년 발사예정인 우주기반기술 검증용 큐브위성 STEP Cube Lab.의 주요 탑재체인 열선절단방식 힌지구동형 구속분리장치는 높은 체결력 및 저충격 구현의 장점으로 초소형위성 전개구조물의 구속/분리에 적용이 용이하며, 기존 나일론선 절단방식의 낮은 체결력 및 복수구조물 적용에 따른 시스템 복잡화의 단점을 극복가능하다. 본 논문에서는 인증모델 검증시험이 완료된 구속분리장치의 궤도검증 임무수행을 목적으로 체결력 검증 및 전개 확인 신호 획득이 가능한 비행모델을 설계/제작하였으며, 탑재체 레벨에서의 발사 및 궤도환경 검증시험을 수행하여 설계 유효성을 입증하였다.

• 대한기계학회논문집A
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• 제37권7호
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• pp.899-903
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• 2013

셀프베어링 모터는 하나의 자기 구동기(magnetic actuator)로 회전 구동과 자기부상을 동시에 구현한 전동기로 베어링리스모터 혹은 베어링 내장 모터로 불리기도 한다. 셀프베어링 모터에서 자기부상제어를 구현하기 위해 부상력과 제어전류 간의 모델을 역변환하여야 하는데, 힘-전류 간의 모델을 결정하는 변환행렬이 정방행렬이 아니며, 의사역행렬(pseudo-inverse) 또한 회전자의 각도에 따라 특이점을 가지게 된다. 본 논문에서는 힘-전류 모델에 제한조건을 추가하여 연속적 역변환이 가능한 새로운 방법을 제시하고, 역변환 행렬을 해석적으로 구하였다. 연속적 역변환을 이용한 부상제어기를 구현하여 안정적 부상제어가 이루어짐을 확인하였다. 힘-전류 모델에 추가한 제한조건으로 상전류의 총합이 0 을 유지하여 전류에 의한 고정자 자속밀도를 제거함으로써, 이전 연구에서의 자기포화 문제를 근본적으로 해결하였다.

• International Journal of Precision Engineering and Manufacturing
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• 제2권4호
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• pp.61-68
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• 2001

A new approach for motion control of constrained mechanical systems is proposed in this paper. The approach uses a new equations of motion which is proposed by Udwadia and Kalaba and named Udwadia-Kalaba's equations of motion in this paper. This paper reveals that the Udwadia-Kalaba's equations of motion is more adequate to model constrained mechanical systems rather than the famous Lagrange's equations of motion at least for control purpose. The proposed approach coverts most of constraints including holonomic and nonholonomic constraints. Comparison of simulation results of two systems which are well-known in the literature show the superiority of the proposed approach. Furthermore, a special constrained mechanical system which includes nonlinear generalized velocities in its constraint equations, which has been considered to be difficult to control, can be controlled easily. It shows the possibility of the proposed approach to being a general framework for motion control of constrained mechanical systems with various kinds of constraints.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.191-196
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• 2005

In this study, to describe vehicle-track-bridge dynamic interaction phenomena with 1/4 vehicle model, nonlinear Hertzian contact spring and nonlinear contact damper are introduced. In this approach external loads acting on 1/4 vehicle model are self weight of vehicle and geometry information of running surface. The constraint equation on contact surface is implemented by Penalty method. Also, to improve the numerical stability and to maintain accuracy of solution, the artificial damper and the reaction from constraint violation are introduced. A nonlinear time integration method, in this study, Newmark method is adopted for both equations of vehicles and structure. And to reduce the error caused by inadequate time step size, adaptive time-stepping technique is partially introduced. As the nonlinear Hertzian contact spring has no resistance to tensile force, the bouncing phenomena of wheelset can be described. Thus, it is expected that more versatile dynamic interaction phenomena can be described by this approach and it can be applied to various railway dynamic problems.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.130-134
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• 1992

The ability of a robot system to comply to an environment via the control of tool-environment interaction force is of vital for the successful task accomplishment in many robot application. This paper presents the implementation of external force control for two dimensional contour following task using a commercial robot system. Force accommodation is used since a constraint imposed in our work is not to modify the commercial robot system. A linear, decoupled model of two dimensional contour following system in the discrete time domain is derived first. Then the experimental verification of linear control is obtained using a PUMA 560 manipulator with standard Unimation controller, Astek FS6-120A six axis wrist force sensor attached externally to the arm and LSI-11173 microcomputer. Experimentally obtained data shows that the RMS contact force error is 0.8246 N when following the straight edge and 2.3768 N when following 40 mm radius curved contour.

• Structural Engineering and Mechanics
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• 제83권6호
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• pp.789-798
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• 2022

The stud shear connector is the main force transfer member in the steel-concrete composite member, and the mechanical behavior is very complicated in the concrete. The concrete around the stud is subjected to the pry-out local pressure concentration of the stud, which can easily produce splitting mirco-cracks. In order to solve the problem of pry-out local splitting of stud shear connector, a kind of stud shear connector with constraint measure is proposed in this paper. Through the push-out test, the interface shear behavior of the new stud shear connector between steel and concrete flange plate was studied, and the difference between the new stud shear connector and the traditional stud connector was compared. The results show that the stud shear connector with constraint measure can effectively avoid the adverse effect of local pressure splitting by relying on its own constraint measure. The shear stiffness of the interface between steel and concrete flange plates is greatly improved, which provides a theoretical basis for the design of strong connection coefficient of steel-concrete composite structures.

• Journal of Mechanical Science and Technology
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• 제19권3호
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• pp.731-742
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• 2005

A magnetic bearing even with multiple coil failure can produce the same decoupled magnetic forces as those before failure if the remaining coil currents are properly redistributed. This fault-tolerant, force invariance control can be achieved with simply replacing the distribution matrix with the appropriate one shortly after coils fail, without modifying feedback control law. The distribution gain matrix that satisfies the necessary constraint conditions of decoupling linearized magnetic forces is determined with the Lagrange Multiplier optimization method.