• Journal of Advanced Navigation Technology
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• v.19 no.1
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• pp.33-40
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• 2015

Advanced surface movement guidance and control system (A-SMGCS) is a system providing routing, guidance and surveillance for the control of aircraft and vehicles in order to maintain the predetermined surface movement rate under all weather conditions while maintaining the required level of safety. In the present study, system engineering was introduced to develop the compliance procedure for the A-SMGCS. At first, requirements for the level IV A-SMGCS were defined and analyzed from the concept of operations (CONOPS). Then, system architecture and specifications were constructed through the functional analysis and allocation. After that, work breakdown structure (WBS) and related integrated master schedule (IMS) were established. Lastly, compliance checklist (CCL) and test and evaluation master plan (TEMP) were developed to verify and validate the system.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.1
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• pp.21-27
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• 2002

Inspection and shape measurement of three-dimensional objects are widely needed in industries for quality monitoring and control. A number of visual or optical technologies have been successfully applied to measure three-dimensional surfaces. However, those conventional visual or optical methods have inherent shortcomings such as occlusion and variant surface reflection. X-ray vision system can be a good solution to these conventional problems, since we can extract the volume information including both the surface geometry and the inner structure of any objects. In the x-ray system, the surface condition of an object, whether it is lambertian or specular, does not affect the inherent characteristics of its x-ray images. In this paper, we propose a three-dimensional x-ray imaging method to reconstruct a three dimensional structure of an object out of two dimensional x-ray image sets. To achieve this by the proposed method, two or more x-ray images projected from different views are needed. Once these images are acquired, the simultaneous algebraic reconstruction technique(SART) is usually utilized. Since the existing SART algorithms have several shortcomings such as low performance in convergence and different convergence within the reconstruction volume of interest, an advanced SART algorithm named as USART(uniform SART) is proposed to avoid such shortcomings and improve the reconstruction performance. Because, each voxel within the volume is equally weighted to update instantaneous value of its internal density, it can achieve uniform convergence property of the reconstructed volume. The algorithm is simulated on various shapes of objects such as a pyramid, a hemisphere and a BGA model. Based on simulation results the performance of the proposed method is compared with that of the conventional SART method.

• Geomechanics and Engineering
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• v.38 no.3
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• pp.215-229
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• 2024

Because of the various patterns of deep-water inrush and complicated mechanisms, accurately predicting mine water inflows is always a difficult problem for coal mine geologists. In study presented in this paper, the water inrush channels were divided into four basic water diversion structures: aquifer, rock fracture zone, fracture zone and goaf. The fluid flow characteristics in each water-conducting structure were investigated by laboratory tests, and multistructure and multisystem coupling flow analysis models of different water-conducting structures were established to describe the entire water inrush process. Based on the research of the water inrush flow paths, the analysis model of different water inrush space structures was established and applied to the prediction of mine water inrush inflow. The results prove that the conduction sequence of different water-conducting structures and the changing rule of permeability caused by stress changes before and after the peak have important influences on the characteristics of mine water-gushing. Influenced by the differences in geological structure and combined with rock mass RQD and fault conductivity characteristics and other mine exploration data, the prediction of mine water inflow can be realized accurately. Taking the water transmitting path in the multistructure as the research object of water inrush, breaking through the limitation of traditional stratigraphic structure division, the prediction of water inflow and the estimation of potentially flooded area was realized, and water bursting intensity was predicted. It is of great significance in making reasonable emergency plans.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.1
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• pp.148-157
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• 2017

Miniature guided-bullet is an advanced military technology of developing guided missile which is designed to hit a target precisely while having easily carriable miniature size. A key issue of developing such system involves size reduction of the original guided missile system, and this in turn arouses stiffness issue regarding small and thin sized control surface. In this study, procedures on how to calculate the critical flutter speed of special type of control surface with the change of its dimension or material property is arranged. During this procedure, design parameters related to critical flutter speed are abridged to help preliminary design of similar structure even faster than time-consuming, and cumbersome computer analysis.

• Structural Engineering and Mechanics
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• v.66 no.2
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• pp.161-172
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• 2018

The passive control of structures using a pendulum tuned mass damper has been extensively studied in the technical literature. As the frequency of the pendulum depends only on its length and the acceleration of gravity, to tune the frequency of the pendulum with that of the structure, the pendulum length is the only design variable. However, in many cases, the required length and the space necessary for its installation are not compatible with the design. In these cases, one can replace the classical pendulum by a virtual pendulum which consists of a mass moving over a curved surface, allowing thus for a greater flexibility in the absorber design, since the length of the pendulum becomes irrelevant and the shape of the curved surface can be optimized. A mathematical model for a building with a pendular tuned mass damper and a detailed parametric analysis is conducted to study the influence of this device on the nonlinear oscillations and stability of the main system under harmonic and seismic base excitation. In addition to the circular profiles, different curved surfaces with softening and hardening characteristics are analyzed. Also, the influence of impact on energy dissipation is considered. A detailed parametric analysis is presented showing that the proposed damper can not only reduce sharply the displacements, and consequently the internal forces in the main structure, but also the accelerations, increasing user comfort. A review of the relevant aspects is also presented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1592-1594
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• 2009

This paper presents an LMI-based method to design a reduced order output feedback sliding mode controller for a class of uncertain systems. Using LMIs we derive an existence condition of a reduced order sliding mode control law. And we give explicit formulas of the gain matrices. Finally, we give a numerical design example, together with a design algorithm.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.703-706
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• 1999

In this paper, robust vibration control of a one-link flexible robot arm based on variable structure system is discussed. We derive dynamic equations of it using a Lagragian assumed modes method based on Bernoulli-Euler beam theory. The optimal sliding surface is designed and the problem of chattering is also solved by the adoptation of a continuous control law within a small neighborhood of the switching hyperplane.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.5
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• pp.607-612
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• 2013

The effect of the flow actuator on the asymmetric vortex structure around the ogive-cylinder body with fineness ratio of 4 flying at the speed of Mach 0.1 at angle of attack of 50 degree is studied. The ogive-cylinder model is developed with the actuator placed near the nose tip and numerically simulated using the in-house CFD code named KFLOW. The numerical simulation employs two different actuator modeling: one is the boundary condition given by blowing normal to the surface and another shearing on the surface. The numerical simulation reveals that response of the vortex structure to the actuation is dependent on the type of modeling as well as the strength and direction of the actuation.

• Ceramist
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• v.22 no.3
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• pp.243-255
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• 2019

Graphene, a two-dimensional material with a single atomic layer, has recently become a major research focus in various applications such as electronic devices, sensors, energy storage, catalysts, and adsorbents, because of its large theoretical surface area, excellent electrical conductivity, outstanding chemical stability, and good mechanical properties. Recently, 3D nanoporous graphene structures have received tremendous attention to expand the application of 2D graphene. Here, we overview the synthesis of 3D nanoporous graphene network structure with two-dimensional graphite oxide sheets, the control of porous parameters such as specific surface area, pore volume and pore size etc, and the modification of electronic structure by heteroatom doping along with its various applications. The 3D nanoporous graphene shows superior performance in diverse applications as a promising key material. Consequently, 3D nanoporous graphene can lead the future for advanced nanotechnology.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.211-214
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• 2005

This research studied robust design of composite structure under combined loading of bending and torsion. DOE (Design of Experiment) technique was used to find important design factors. The results show that the beam height, beam width, layer thickness and stack angle of outer-layer are important design parameter. The $2^{nd}$ DOE and RSM (Response Surface Model) were conducted to obtain optimum design. Multi-island genetic algorithm was used to optimum design. An approximate value of 6.65 mm in deflection was expected under optimum condition. Six sigma robust design was conducted to find out guideline for control range of design parameter. To acquire six sigma level reliability, the sigma level reliability, the standard deviation of design parameter should be controlled within 2.5 % of average design value.