• 한국정밀공학회지
• /
• 제15권5호
• /
• pp.93-99
• /
• 1998

Although laser interferometer measurement system has advantages of measurement range and accuracy, it has some disadvantages when measurement of multi degrees of freedom of motion are required. Because the traditional error measurement methods for geometric errors (two straightness and three angular errors) of a slide of machine tools measures error components one at a time. It may also create an optical path difference and affect the measurement accuracy. In order to identify and compensate for geometric errors of a moving rigid body in real time processes, an on-line error measurement system for simultaneous detection of the five error components of a moving object is required. Using laser alignment technique and some optoelectronic components, an on-line measurement system with 5 degrees of freedom was developed for the geometric error detection in this study Performance verification of the system has been performed on an error generating mechanism. Experimental results show the feasibility of this system for identifying geometric errors of a slide of machine tools.

• Earthquakes and Structures
• /
• 제7권6호
• /
• pp.1071-1091
• /
• 2014

Pounding of adjacent structures are always a notable reason for damages after strong ground motions, but it is already unforeseen detail in newly constructed structures. Thus, several approaches have been proposed in order to prevent the pounding of structures. By using optimally tuned mass dampers, it is possible to decrease the displacement vibrations of structures. But in adjacent structures, the response of both structures must be considered in the objective function of optimization process. In this paper, two different designs of Tuned Mass Dampers (TMD) are investigated. The first design covers independent TMDs on both structures. In the second design, adjacent structures are coupled by a TMD on the top of the structures. Optimum TMD parameters are found by using the developed optimization methodology employing harmony search algorithm. The proposed method is presented with single degree of freedom and multiple degree of freedom structures. Results show that the coupled design is not effective on multiple degree of freedom adjacent structures. The coupled design is only effective for rigid structures with a single degree of freedom while the use of independent TMDs are effective on both rigid and flexural structures.

• Computers and Concrete
• /
• 제4권2호
• /
• pp.135-156
• /
• 2007

Three 3D nonlinear finite-element models are developed to study the behavior of concrete beams and plates with and without external reinforcement by fibre-reinforced plastic (FRP). All three models are formulated based upon the 3D theory of elasticity. The stress model is modified from the element developed by Ramtekkar, et al. (2002) to incorporate material nonlinearity in the formulation. Both transverse stress and displacement components are used as nodal degrees-of-freedom to ensure the continuity of both stress and displacement components between the elements. The displacement model uses only displacement components as nodal degrees-of-freedom. The transition model has both stress and displacement components as nodal degrees-of-freedom on one surface, and only displacement components as nodal degrees-of-freedom on the opposite surface. The transition model serves as a connector between the stress and the displacement models. The developed models are validated by comparing the results of the analyses with an existing experimental result. Parametric studies of the effects of the externally reinforced FRP on the load capacity of reinforced concrete (RC) beams and concrete plates are performed to demonstrate the practicality and the efficiency of the proposed models.

• 한국기계가공학회지
• /
• 제2권4호
• /
• pp.33-39
• /
• 2003

The stiffness of multi-articulated industrial robots is very weak, because their structure is an articulated type with some links and joints. Thus it is known that cutting processes for metals are not accepted in machine shop well, but they have a lot of merits for cutting processes, for example, drilling, tapping, and engraving etc, because of the characteristics of their high degree of freedom. The temptation of cutting aluminium was carried out to investigate the feasibility and the limitations or constraints for cutting metals on them. First the mode shapes of 6 degree of freedom welding robot were taken and analysed, and next the cutting processes were practically carried out on it. The results of study were found out to show the feasibility of cutting processes at drilling under 6mm of tool diameter, as well as to have some limitations and constraints, for examples, feed rate, depth of cut and cutting force etc.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
• /
• pp.411-416
• /
• 2000

Cutting process has been automated by progress of CNC and CAD/CAM, but polishing process has been depended on only experiential knowledge of expert. To automate the polishing process, a polishing robot with w degrees of freedom which is attached to a machining center with 3 degrees of freedom has been developed. This automatic polishing robot is able to keep the polishing tool normal on the curved surface of die to improve a performance of polishing. Polishing task for a curved surface die demands repetitive operation and high precision, but conventional control algorithm can not cope with the problem of disturbance such as a change of load. In this research, a new sliding mode control algorithm is applied to the robot. The signal compression method is used to identify polishing robot system. to obtain an effect of 5 degrees of freedom motion, a synchronization between the machining center and polishing robot is accomplished by using M code of machining center. And also a trajectory for polishing the curved surface die by 5 degrees of freedom motion, a synchronization between the machining center and polishing robot is accomplished by using M code of machining center. And also a trajectory for polishing the curved surface die by 5 axes machining center is divided into data of two types for 3 axes machining center and 2 axes polishing robot. To evaluate polishing performance of the robot. various experiments are carried out.

• 문화기술의 융합
• /
• 제2권1호
• /
• pp.45-51
• /
• 2016

아리스토텔레스는 시란 독자로 하여금 행복을 줄 수 있고, 치료적 효과를 안겨줄 수 있는 것으로 말한다. 그는 이것을 고유한 형상을 복원한다는 의미로 재현再現이라고 하였다. 이에 칸트는 재현뿐 아니라 미학으로 표현되는 시에는 자유가 있어야 더 격상된 것이라고 보았다. 그의 미감적 판단의 독특성을 '지성과 상상력의 자유로운 유희의 결과'라고 하였다. 칸트의 말은 예술적 창조의 정신이 사람이 행할 수 있는 도덕적 이념과 결합하는 데서 최고의 즐거움을 맛볼 수 있다고 한 것이다. 필자는 이에 독자의 입장에서 소통과 유희를 더해야 한다고 여긴다. 왜냐하면 시는 행복과 자유를 위해서 그 밑바탕에 소통과 유희가 어우러져야하기 때문이다.

• 융합신호처리학회논문지
• /
• 제11권1호
• /
• pp.74-79
• /
• 2010

많은 제어기법들이 제어계의 제어성능을 개선하기 위해 제안되고 있다. 제어계에서 제어에 대한 자유도는 독립적으로 조정할 수 있는 폐루프 전달함수의 수로 결정된다. 목표치 추종 및 외란억제에 대해 2자유도 제어기법이 많이 이용되고 있다. 본 논문에서는 외란을 제거하기 위해 외란관측기를 갖는 제어계를 2자유도 제어계로 변환시켰으며, 기동 및 부하변동 시 과도응답의 제거를 용이하게 하였다. 그리고 외란관측기의 설계법이 주파수 영역으로 제안하였으며, 이 방법으로 설계된 외란관측기를 이용하여 2자유도 제어계를 구성하였다. 시뮬레이션 결과를 통하여 제안한 알고리즘의 유효성을 확인 하였다.

• 한국컴퓨터정보학회논문지
• /
• 제22권10호
• /
• pp.151-157
• /
• 2017

In the case of uploading privacy information of an information owner in the Internet, the information owner may want to deliver the privacy information itself or remove such information from the search list in order to prevent third parties from accessing the privacy information of the information owner. Such a right to be forgotten may collide with the freedom of expression of a third party. The right to be forgotten, which originates from the self-determination right on privacy information based on Article 10 and 17 of the Constitution and the freedom of expression, which is based on Article 21 thereof are all relative basic rights and are both limited by Item 2 under Article 37 of the same law, which is the general limitation provision for the basic rights. Therefore, when the right to be forgotten and the freedom of expression collides, it is not possible to give priority to one of the those unilaterally. It depends on the nature of the case at hand to find a natural balance for the harmonious solution for both parties. The criteria can be the sensitivity to the privacy of the information owner caused by the disclose of the privacy information, the public benefits such information may serve, the social common good that could be expected by the disclosure of the privacy information and the damages suffered in terms of the personal interest caused by the disclosure of the information, in a comprehensive manner.

• Journal of Electrical Engineering and Technology
• /
• 제12권3호
• /
• pp.1227-1234
• /
• 2017

The two-degree-of-freedom direct drive induction motor, which is capable of linear, rotary and helical motion, has a wide application in special industry such as industrial robot arms. It is inevitable that the linear motion and rotary motion generate coupling effect on each other on account of the high integration. The analysis of this effect has great significance in the research of two-degree-of-freedom motors, which is also crucial to realize precision control of them. The coupling factor considering the coupling effect is proposed and addressed by 3D finite element method. Then the corrected mathematical model is presented by importing the coupling factor. The results from it are verified by 3D finite element model and prototype test, which validates the corrected mathematical model.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제49권9호
• /
• pp.495-503
• /
• 2000

In this paper we propose a design procedure of loop-shaping two-degree-of-freedom H$\infty$ digital controller for sampled-data system. We extend the continuous time loop-shaping two-degree-of-freedom H$\infty$ control problem to sampled-data system. The configuration of generalized plant is modified for sampled-data system. And then using continuous lifting we obtain the digital controller. In the final stage of loop-shaping procedure the problem of absorbing weighting functions is discussed. We summarize this study to the design procedure and illustrate the application for an inverted pendulum on the cart.