• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.141-142
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• 2009

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.6
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• pp.169-174
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• 2019

Flexure joints are recently used in the ultra-precision mechanism for a telecommunication mirror stage. Flexure joints have several advantages coming from their monolithic characteristics. They can be used to reduce the size of manipulators or to increase the precision of motion. In our research, 6 dof(degree of freedom) mechanism is suggested for micrometer repeatability using a flexure mechanism. To design the 6-dof motion, the 2-dof planar mechanism are designed and assembled to make the 6-dof motion. To achieve a certain performance, it is necessary to define the performance of mechanism that quantifies the characteristics of flexure joints. This paper addresses the analysis and design of the 6-dof parallel manipulator with a flexure joint using a finite element analysis tool. To obtain experimental result, CCD laser displacement sensor is used for the total displacement and the stiffness for the 6-dof flexure mechanism.

• Computational Structural Engineering
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• v.8 no.2
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• pp.153-161
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• 1995

The dynamic instability for snapping phenomena has been studied by many researchers. There is few paper which deal with the dynamic buckling under the load with periodic characteristics, and the behavior under periodic excitation is expected the different behavior against step excitation. In this study, the dynamic direct snapping of shallow elliptic paraboloidal shells is investigated under not only step excitation but also sinusoidal and seismic excitations, applied in the up-and-down direction. The dynamic nonlinear responses are obtained by the numerical integration of the geometrically nonlinear equations of motion, and examined by the Fourier spectral analysis in order to get the frequency-dependent characteristics of the dynamic instability for various load levels. The results show that the dynamic instability phenomenon carried out from stable to unstable region reveals considerably different mechanism depending on the characteristics of excitations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.11
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• pp.871-884
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• 2015

Fluid transport is a key issue in the development of microfluidic systems. Recently, Myong (2014) has proposed a new concept for droplet transport without external power sources, and numerically validated the results for a hypothetical 2D shape, initially having a hemicylindrical droplet shape. Myong and Kwon (2015) have also examined the transport mechanism for an actual water droplet, initially having a 3D hemispherical shape, on a horizontal hydrophilic/hydrophobic surface, based on the numerical results of the time evolution of the droplet shape, as well as the total kinetic, gravitational, pressure and surface free energies inside the droplet. In this study, a 3D numerical analysis of an initially spherical droplet is carried out to establish a new concept for droplet transport. Further, the transport mechanism of an actual water droplet is examined in detail from the viewpoint of the capillarity force imbalance through the numerical results of droplet shape and various energies inside the droplet.

• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.371-383
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• 2014

이 연구에서는 팔라듐 착물 $Pd(PPh_3)_2$을 사용한 bromotoluene과 morpholine간의 coupling reaction (Buchwald-Hartwig amination) 반응 메커니즘을 계산화학적 방법을 이용하여 연구하였다. 용매화 자유에너지를 고려한 중간체 에너지를 비교하였으며, 반응물질이 o-bromotoluene 일 때와 p-bromotoluene 일 때, 반응 중간체로 monophosphine 착물이 형성되는 경우와 bisphosphine 착물이 형성되는 경우를 비교하였으며, 반응 중간체로 bisphosphine 착물이 형성되는 경우 cis 이성질체가 중간체인 경우와 trans 이성질체가 중간체인 경우를 비교하였다. 그 결과, 반응물로 p-bromotoluene을 사용할 때 o-bromotoluene을 사용할 때보다 중간체가 상대적으로 더 안정하여 더 좋은 수득률을 얻을 수 있을 것으로 예상되었다. 또한 $Pd(PPh_3)_n(o-tolyl)(N(CH_2CH_2)_2O)$ (n=1 또는 2) 중간체를 제외하고는 모든 경우에서 bisphosphine 중간체가 형성되는 반응경로가 더 안정한 것으로 밝혀졌다. 그리고 $Pd(PPh_3)_2ArBr$의 경우 trans 이성질체가 cis 이성질체보다 안정하지만 $Pd(PPh_3)_2Ar(N(CH_2CH_2)_2O)$의 경우 반대로 cis 이성질체가 trans 이성질체보다 안정한 것으로 나타났다.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.7-10
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• 2003

뱀형 로봇은 자유도보다 액추에이터의 수가 적은 논홀로믹 구속조건(nonholonomic constraint)을 가지며, 단순한 신체구조 이지만 초-여유자유도 구속조건(hyper-redundant constraint)을 이용해서 기밀한 운동과 다양한 기능을 만들어내는 특징을 가지고 있다. 본 논문에서는 6개의 관절로 각 링크가 2차원 상에서 직렬로 연결된 뱀형 로봇의 기구설계 및 기구학과 동력학을 바탕으로 설계된 기구에 대해 해석하여 운동방정식을 유도하여 추진원리와 운동원리에 관하여 알아본다. 기본적인 운동 메커니즘을 해석하여 구현한 알고리즘을 제작한 로봇에 적용하여 추진 원리와 운동원리를 검증한다. 실험용 로봇은 링크 중앙에 법선 방향으로 마찰력이 발생할 수 있도록 수동바퀴를 가지고 있으며, PC와 RF(Radio Frequency)로 직렬통신을 하며 PC에서의 운동 명령의 조작에 의해 전진, 후진, 좌/우 방향으로 회전을 할 수 있도록 운동 알고리즘을 적용할 수 있도록 제작되었다. 특징으로는 일반적으로 토크를 입력으로 하지 않고 각도를 입력으로 하여 관절을 제어하고 있다는 점이 있으며, 운동방정식 또한 이에 대한 관계를 바탕으로 유도한 것이다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.66.2-66.2
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• 2012

프린팅공정을 이용한 패터닝 기술은 디스플레이, 태양전지, RFID 등 다양한 분야에서 각광을 받고 있다. 프린팅공정은 대면적 패터닝 공정이 가능하며, 다단계 공정인 Litho보다 공정이 단순하다는 장점이 있지만, 현재까지 원하는 크기와 두께의 패턴구현이 쉽지 않다는 단점이 있다. 프린팅 공정을 전자소자의 패터닝 기술로 사용하기 위해서는, 다양한 선폭과 선 두께를 자유자재로 구현하는 것이 가능해야 한다. 또한 미세한 선폭을 인쇄할 수 있을 수록 더 미세한 전자소자 또는 디스플레이 소자를 만들어 낼 수 있으며, 박막을 구현하는 것은 유기소자를 인쇄방식으로 하기 위해서는 필수적이다. 본 논문은 이러한 정밀한 패터닝이 가능한 롤 인쇄 공정의 기본 메커니즘을 설명하고 이를 이용한 미세 박막 인쇄 공정을 실험을 통해 검증하였다.

• The Journal of Korea Robotics Society
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• v.17 no.2
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• pp.209-215
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• 2022

In this paper, a forearm Mechanism design inspired by ligamentous structure of the human body is proposed. The proposed mechanism consists of four rigid bodies and fourteen wires without any mechanical joints. Actually, the mechanism is based on the concept of the tensegrity structure. Therefore, the proposed mechanism has inherently compliant characteristics due to the flexibility of the wires composing the structure. Rigid bodies and wires of the mechanism mimic bones and major ligaments in the forearm of the human. The proposed mechanism is classified as one of the interconnected hybrid flexure systems. The analysis method of the degree of freedom (DOF) of the proposed mechanism is also introduced through analyzing technique of the interconnected hybrid flexure systems, in this paper. Ultimately, the proposed mechanism, whose structure is complicated with rigid bodies and wires, mathematically drives that it has 3-DOFs.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.5
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• pp.405-414
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• 2015

Fluid transport is a key issue in the development of microfluidic systems. Recently, Myong (2014) has proposed a new concept for droplet transport without external power sources and numerically validated the results for a hypothetical 2D, initially having a hemicylindrical droplet. In this paper, the movement of an actual water droplet, initially having a 3D hemispherical shape, on horizontal hydrophilic/hydrophobic surfaces is simulated using a commercial computational fluid dynamics (CFD) package, Fluent, with VOF (volume of fluid) method. The results are compared with the 2D analysis of Myong (2014), and the transport mechanism for the actual water droplet is examined based on the numerical results of the time evolution of the droplet shape, as well as the total kinetic, gravitational, surface free and pressure energies inside the droplet.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.8
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• pp.81-87
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• 2020

A stable rotational-to-linear motion transformation structure using a driving mechanism with 2 degrees of freedom was developed for an orthogonal mechanism to prevent the interference of each axis in 2D motion. In this mechanism, a step motor was used for precise position control. This structure was developed to maneuver workparts in micro particle blast machining experiments. To determine the real-time performance of micro particle blast machining, the control, input, and output were operated simultaneously and precise position control was implemented, using a timer interrupt with multiple execution codes. The two step motors obtained precise position control by removing backlash with a ball-screw mechanism. The device has menu-type control codes for user-friendliness, and real-time sequence control was simultaneously adopted for user control input.