• Transactions of The Korea Fluid Power Systems Society
• /
• v.7 no.3
• /
• pp.20-27
• /
• 2010

A vehicle suspension system performs two functions, the ride quality and the stability, which conflict with each other. An active suspension system has an external energy source, from which energy is always supplied to the system for continuous control of vehicle motion. Therefore, an active suspension system can have even more improved performance. Some control laws have been proposed for active suspension system, but in this paper, an optimal variable structure control(VSC) is proposed. The VSC method is well suited for a class of nonlinear system and can address the robustness issues to constant modelling errors and disturbances. This paper develops an optimal VSC controller and compares its performance to those of a passive suspension system and an active suspension system with an optimal controller. The transient and frequency responses are analyzed respectively.

• Aerospace Engineering and Technology
• /
• v.2 no.1
• /
• pp.11-21
• /
• 2003

This paper deals with preliminary design results of autopilot for station keeping mode of airship. Linear equations of motion for the airship are derived. Basic architecture of the control laws for cruising and station keeping modes are proposed. Performance analysis results show that autopilot design for station keeping mode of airship is feasible.

• Proceedings of the IEEK Conference
• /
• 2009.05a
• /
• pp.156-158
• /
• 2009

A graphic simulator is efficient to see what will happen to the target robot. But it is not exactly same as the real world. Because there are so many physical laws to be concerned. In this paper, we propose a simulator with physics engine to create motions for quadruped robot. It is not only to show more real simulations but also to be more efficient for teaching motions to quadruped robot. To solve the quadruped robot's dynamics or inverse kinematics, It takes much times and hard effort. Using physics engine make it easy to setup motions without calculating inverse kinematics or dynamics.

• Earthquakes and Structures
• /
• v.17 no.6
• /
• pp.591-598
• /
• 2019

The most recent shaking experiences have demonstrated that the predictions of the seismic models are not always in agreement with the registered responses, especially in the face of extreme earthquakes. Records collected from 1960 to 2011 at a rock-like site are used to develop a neural network that permits to estimate peak ground accelerations via the magnitude, the focal depth, the site-source distance and a seismogenic zone. The neural model is applied to the 8th and 19th September 2017 events that hit Mexican territory and the obtained results show that the network is flexible enough to work appropriately to various conditions of intensity and sites-sources with remarkably predictive capacity. The neural-attenuation curves are compared with those obtained from Ground Motion Prediction Equations and their performance is assessed for events, in addition to the devastating Mexican events, from Japan, Taiwan, Chile and USA.

• Journal of Korean Medical classics
• /
• v.21 no.2
• /
• pp.113-124
• /
• 2008

The main characteristic of 'Idea of Uimul(宜物思想)' lies in specifically laying down rules on the subject of thought, and creating correlated measures and ways based on those grounds. Thus, 'Ui(宜)' emphasizes the pertinence of the measures and ways. By making a detailed analysis, the importance of 'Mul(物)', the subject of thought, the perception of it, the human reaction to it, and the specific principle of the action, can be seen. Ancient Chinese considered Heaven and Earth the largest frame of perception, and perceived all things through it. Heaven and Earth was differentiated from 'Gi'(氣), and the Gi of Heaven and the Gi of Earth interacted with one another in endless motion. "Hwangjenaegyeong(黃帝內經)" considered nature and all things in it through this ideology of 'Correspondence between Heaven and Humanity(天人相應)'. It considered humans to be born from the Gi of Heaven and Earth and to associate with one another under the influence of the Gi of Heaven and Earth. Therefore, in "Hwangjenaegyeong(黃帝內經)", the ideology of 'Correspondence between Heaven and Humanity(天人相應)' is the fundamental frame of Idea of Uimul(宜物思想). On the other hand, the Ui(宜) in Idea of Uimul(宜物思想) indicates the pertinent measures and ways towards a subject, that is, humans acting appropriately according to the laws of Heaven and Earth inside the ideology of 'Correspondence between Heaven and Humanity(天人相應)'. Humans are affected by nature and adapt to it, but they also recognize the laws of nature and strive to wholly protect the human life by versatilely taking adequate measures against the numerous changes of nature.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.905-912
• /
• 2009

1-g shaking table test is conducted to evaluate the dynamic behavior of a soil-structure system under seismic loading condition. A consistent similitude law between the model and prototype is needed to predict the behavior of the prototype structure, quantitatively. The natural frequency of geomaterial decreases with the increase of shaking intensity because of the non-linear property of the geomaterial. This phenomenon affects the applicability of similitude laws in 1-g shaking table tests. In this study, a simple method is suggested to determine the frequency of the input motions in 1-g tests in order to enhance the applicability of similitude laws. Modified input frequency is calculated using the frequency ratio with consideration of the variation of the natural frequency according to the intensity of input ground acceleration. To verify the applicability of the suggested method, a series of 1-g shaking table tests were performed for three different sizes of model piles having an overburden mass on their heads by varying the acceleration and the frequency of input motion. The acceleration amplification ratio on the overburden mass, the lateral displacement at the pile head and the maximum bending moment along the pile depth were measured. The projected behaviors of the virtual prototype based on the measured values of the model tests, where the input frequencies were calculated by the new method, showed good consistency, verifying the applicability of the suggested method.

• Korean Institute of Interior Design Journal
• /
• v.19 no.1
• /
• pp.236-244
• /
• 2010

The objective of this study is to investigate the difference between the standard 'design guideline' in barrier free laws for the disabled and the disabled's real experience in public convenient facilities. It is mainly focused on accessibility by the disabled people who use an electric motion wheel chair, a wheel chair and crutches as well as a visual impaired person in the public resident centers. For this purpose, four resident centers in Busan have been selected as the objects of investigation. We observed and video recorded the disabled people with various handicaps to access and use facilities in four resident centers, and interviewed them afterwards. We found out problems from the perspective of the disabled and figured out the difference between barrier free laws and the disabled's real experience. The research result is as follows. First, it is important to make the arrangement of public convenient facilities according to the flow of the user's movements. Second, it is necessary to provide better conditions for the disabled to access the public toilet easily and conveniently. Third, it is essential for public convenient facilities to be more strictly controlled by regulations. Fourth, we need to make better standards that could reflect real experiences of various disabled users. Fifth, we need to keep providing the best follow-up service for the disabled in terms of using public convenient facilities safely. This study can contribute for designers to understand specific users through their experiences and suggest improvement ideas for better public convenient Facilities.

• International Journal of Aeronautical and Space Sciences
• /
• v.18 no.4
• /
• pp.623-640
• /
• 2017

The full nonlinear equations of an unmanned aerial vehicle ground taxiing mathematical dynamic model are built based on a type of unmanned aerial vehicle data in LMS Virtual.Lab Motion. The flexible landing gear model is considered to make the aircraft ground motion more accurate. The electric braking control system is established in MATLAB/Simulink and the experiment of it verifies that the electric braking model with the pressure sensor is fitted well with the actual braking mechanism and it ensures the braking response speediness. The direction rectification control law combining the differential brake and the rudder with 30% anti-skid brake is built to improve the directional stability. Two other rectifying control laws are demonstrated to compare with the designed control law to verify that the designed control is of high directional stability and high braking efficiency. The lateral displacement increases by 445.45% with poor rectification performance under the only rudder rectifying control relative to the designed control law. The braking distance rises by 36m and the braking frequency increases by 85.71% under the control law without anti-skid brake. Different landing conditions are simulated to verify the good robustness of the designed rectifying control.

• Journal of Korean Philosophical Society
• /
• v.148
• /
• pp.157-181
• /
• 2018

The aim of this essay is to identify elements of methodologies to investigate the development of Newtonian dynamics. This methodology involves the transformation and synthesis of preceding theories. My essay attempts to confirm my assertion by analyzing historical case of Newton's discovery of his dynamics. While discovering his mechanistic theory, Newton reconstructed theoretical concepts and structures of intellectual predecessors, such as Aristotle, Descartes, Galileo, and Kepler. Newton's synthesis was possible only after carefully reconstructing the appropriate and useful ideas of previous natural philosophers' ideas. As a result, Newtonian dynamics are completed with these modified and integrated concepts incorporated into Newton's law of motion and space-time concepts. This study consists of two parts. First, Lakatos' research program has been applied in order to analyze the structure of Newtonian dynamics. Second, the aforementioned methodologies of discovery are distilled from the case study.

• The Journal of Korean Philosophical History
• /
• no.29
• /
• pp.203-230
• /
• 2010

This article is aimed for to state the rationality of Mojia and reveal the scientific meaning in the theories related to the motion of objects in Mojing: the basic approach to the principle of gravitation in building castle, and comprehension and application of the principle in the lever devised for improving productivity as well as in an inclined plane. It is denied in this article that the technical advance and the positive influence on the people is achieved by Mojias only because they were occupied in the filed of craft. Mojia was one of the schools of Qin in the early stage who realized how important science wass for the better society focused on humanity. Furthermore, they were the frontiers who pursued the proper society through science. Therefore, the scientific theories claimed by Mojia is not emphasized only on the deducting regularity of nature. Instead, it could be theorized only by guaranteeing the welfare for common people and having close relation to it. The Chinese philosophy in the early Twentieth century had vigorous interest in the Mojia's opinions in science and set about conducting study in this part. Based on the study, it was revealed that the Mojia's opinion toward motion is superior to that of the West. Furthermore, it was proved to reflect the main idea in Mojia: the love for common people. Particularly, the theories from Mojia can be so applicable to today's life that some scholars regret the lack of interest in Mojia for the time and even scold themselves for the retarded progress in science of China.