• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.12
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• pp.997-1004
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• 2020

A synchropter is a type of rotorcraft in which a pair of blades inclined with each other rotates in synchronization. Removing the tail rotor enables an efficient and compact configuration similar to a coaxial-rotor helicopter. This paper describes the design and flight test results of a small synchropter to examine the suitability of a drone system for the army. The synchropter in this paper is a small vehicle with a rotor diameter of 1.4m and a weight of 7kg and was assembled based on commercial parts to examine flight characteristics effectively. The flight control system adopted Pixhawk, which is designed based on an open-architecture. The model-based design technique is applied to develop the control law of the synchropter and a new firmware embedded on the Pixhawk. Through qualitative flight tests, we analyzed the flight characteristics. As a result of the analysis, we confirmed the possibility of application as a drone system of the synchropter.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.4
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• pp.284-291
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• 2021

In this paper, we study the consensus problem for multi-agent systems with input saturations. The goal of consensus is to achieve a swarming behavior of multi-agent systems by reaching the agreement through information exchange. This paper considers agents modeled by first-order dynamics with input saturations. In order to guarantee the global convergence of the agents, it is assumed that the agents are stable. Moreover, considering the disturbances, we propose the PI based duplex control method to achieve the consensus. The proposed P controller and I controller are composed of different information network. Then, we investigate the conditions of the information networks and the control gains of P, I controllers to achieve the consensus applying the Lyapunov stability theorem and the Lasalle's Invariance Principle. Finally, we conduct the simulations to validate the theoretical results.

• The Journal of the Korea Contents Association
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• v.7 no.5
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• pp.102-109
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• 2007

This is an analysis study about the pictorial frame of Georges Schwizgebel's animation "The Subject of Picture", focusing on Deleuze's frame theory. First of all, the shapes in the frame of the animation is the representation of the tactile sensation from the erased vestiges of the characters. It shows the metamorphosis of the erased vestiges of the shapes by Deleuze's sensibility theory. Besides, the layout of the animation's background has similar property with the aplat which was mentioned by Deleuze. It means that the background of the animation correspond to the aplat which is other boundary different from reality, and the character which has the minimum embodiment about the object makes the shape newly through the distortion of the shape. Secondly, as the problem of frames in terms of the continuity of time, the meaning in Schwizgebel's animation is created by the relation between each frame. It means that the depiction of the shape itself by the composition between each frame is composed of the frame. Eventually, Schwizgebel's work is the animation which has the characteristic of the modem cinema and is the crystal depiction that deviates from rules and logics of the object which was mentioned by Deleuze.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.21-32
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• 2013

This is a preliminary study for the real-time feedback vibration control of building structures. The study developed a wireless acceleration sensor system based on authentic technology capacities, to integrate with the Prototype AMD system and ultimately construct the feedback vibration control system. These systems were used to evaluate the basic performance levels of the control systems within model building structures. For this purpose, the study first developed a wireless acceleration sensor unit that integrates an MEMS sensor device and bluetooth communication module. Also, the study developed an operating program that enables control output based on real-time acceleration response measurement and control law. Furthermore, the Prototype AMD and motor driver system were constructed to be maneuvered by the AC servo-motor. Eventually, all these compositions were used to evaluate the real-time feedback vibration control system of a 2-story model building, and qualitatively measure the extent of vibrational reduction of the target structure within the laboratory validation tests. As a result of the tests, there was a definite vibrational reduction effect within the laboratory validation tests. As a result of the tests, there was a definite vibrational reduction effect within 1st and 2nd resonance frequency as well as the random frequency of the model building structure. Ultimately, this study confirmed the potential of its wireless acceleration sensor system and AMD system as an effective tool that can be applied to the active vibration control of other structures.

• Journal of The Korean Association For Science Education
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• v.34 no.2
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• pp.79-92
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• 2014

The purpose of this study is to develop an inquiry-based argumentation task for use in science teachers' professional development by providing them with the substantial experience of argumentation. To do so, the study has developed an argumentation task by utilizing the experiment on the Charles' Law of gas and revised by applying to eight teachers three times. We have revised the questions by analyzing three issues that have been revealed throughout this process in ways that facilitated teachers' argumentation. The effects of revision have been confirmed by the improvements in teachers' argumentation pattern. Three issues have been identified in developing argumentation tasks for science teachers' professional development and they are as follows: determining the openness of the structure of a question, achieving cognitive conflict and convergence of opinions at the same time, and ways of utilizing various evidence. As the task has been revised in ways that enabled scientific approach to the inquiry topic and facilitated the convergence of various opinions, the participants' argumentation patterns have improved both quantitatively and qualitatively. Meanwhile, the inclusion of an actual experiment has not influence their argumentation, while the observation of experimental data has been used as the core evidence according to the character of the problem. Based on the study's result, we suggest practical implications for developing argumentation tasks for science teachers in more varying contexts.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.358-367
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• 2013

In the present paper, we apply a porous modelling technique to accurately predict the pressure drop through the strainer by replacing all or some of the filter composed of perforated plates with porous media and there imposing the streamwise and transverse loss coefficients required according to the Forchheimer law and then confirm its effectiveness. At first, the streamwise coefficient is obtained by performing a simple simulation on the pipe flow mimicking the hole flow. Subsequently, the transverse coefficient is obtained by setting a unit pattern to have common flow loss characteristics with the repeated shape patterns in the filter, then performing numerical simulations on the prototype and porous model of the unit shape pattern, and finally comparing their results of pressure drop. To validate the applied modeling technique, we perform the numerical simulation with the two specified loss coefficients on a whole shape of strainer and compare the modeling results with those of the corresponding prototype numerical simulation. Comparison indicates that the modeling technique can predict the pressure drop and flow characteristics comparatively accurately and save the number of nodes closely related to the computational cost (CPU and memory) by about 3~4 times compared with the prototype simulation.

• Journal of the Korean Society for Library and Information Science
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• v.49 no.1
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• pp.201-221
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• 2015

The purpose of this study is to suggest the usability of collection evaluation methods for collection development policy in public libraries. To achieve this purpose, this study applied Bonn's Use Factor, Turnover Rate of Collection, and Trueswell's 80/20 Rule to actual circulation data of the Gwangjin District Public Library in Seoul during last ten years. This study added practical meanings and values in collection evaluation through the analysis of total holdings and subject classes. Main items of analysis are the rate of use to total holdings and to holdings in specific subject classes by year, and the rate of core collection circulation by year. The results show relations between the rate of use and library's performance through the analysis of the rate of use both total holdings and subject classes. The results also figure out user's patterns and library appraisal of community users through the analysis of circulation data. In addition, the analysis of core collection gives a good basis for an effective collection development policy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5827-5833
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• 2013

Due to science and technology evolutions, modern systems are becoming larger and more complex. In developing complex systems, Model-Based Systems Engineering (MBSE), which is approach to reduce complexity, is being introduced and applied to various system domains. However, because of the modeling being made through a variety of languages, there is a problem with communication within the stakeholders and a lack of consistency in the models. In this paper, by investigating the rule explaining the transformation of one of the only traditional diagrams, DFD, to SysML and reusing the formerly built models, we attempt to implement by SysML. Analyzing each diagram's Metamodel and validating the connection of each component through bipartite graph especially suggest an effective transformation rule. Also, by applying to naval-combat system, we confirm efficiency of this study. Establishing the results of this study as basis for conducting further study, we will be able to transform other previous models gained from formerly built system to SysML. In this way, the stakeholder's communication can be improved and we anticipate that the application of SysML will be beneficial to the much efficient MBSE.

• Archives of design research
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• v.11
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• pp.22-29
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• 1995

I have to find standpoint of sight moulding of Chi I Sung Hwa(seven stars picture) analysis of graphic systems of a symbol sight native to our nation. And I will comprehend emotion of folkways by simple and graphic lines and colors in mathematical Grid of which ancestor had expressed in gauge moulding consciousness. This papers aim is to make a contribution to lead by on part of communication design. About structural analysis of pictorial graphic side. I) Mathematical thought of the Orient and space constitution are first basically the Orient expressed number notion of mathematics of unlimitedness and notion of zero so called space and empty second can analigize a diagonal expansion method by development of symmetry notion to basic the dual principle of the negative and positive by degrees development expressed space division method by direction notion. 2) About the proportion analysis it based the golden section globularity and in modern layout it takes vision center of position, after appointing the brow of sacred image of Chil Sung Hwa as center point of proportion and applied to the point proportion and so analigized the posibility of established. Rule in union of each elements and rule of forms about picture image. 3) Mathematical structure analysis to search a unified principle at the balanced arrangement and rule of forms it analigized the standard the rule of forms. it analigized the standard the rule of forms to body module of basic movement of protagonist and follower above basic forms of grid that is the basis of design system.

• Geotechnical Engineering
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• v.13 no.1
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• pp.35-46
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• 1997

The isotropic single-hardening constitutive model has been applied to predict the behavior of soils during reorientation of principal stresses in the field. The predicted response by the model agrees well with the measured behavior for a series of torsion shear tests performed on hollow cylinder specimens of Ko consoildated clay along various stress -paths. This indicates that the soil behavior during reorientation of principal stresses can be predicted by using the model with application of simple informations given by isotropic compression tests and conventional consolidated-undxained triaxial compression tests. Isotropic elasto-plastic soil behavior has been served during primary loading from both the torsion shear tests and the predictions by the model. However, the directions of maj or principal strain increment given by the model have not coincided with the directions for tests during stress reversal, such as unloading and reloading, within isotropic yield surface for Ko consolidated stress. This indicates that kinematic hardening model instead of isotropic hardening model should be developed to predict the soil behavior during stress reversal. The experimental strain increment vectors in the work-space have been compared with the directions expected for associated and nonassociated flow rules.