• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.1
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• pp.56-64
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• 2002

Thermally induced vibration response of composite thin-walled beams is investigated in this paper. The flexible spacecraft appendages modeled as thin-walled beam incorporates a number of nonclassical effects of transverse shear, primary and secondary warping, rotary inertia and anisotropy of constitute materials. Thermally induced vibration responds characteristics of a composite thin walled beam exhibiting the circumferantially uniform system(CUS) configuration are exploited in connection with the structural flapwise bending lagwise bending coupling resulting from directioal properties of fiber reinforced composite materials and ply stacking sequence. A coupled thermal structure gradient is investigated.

• International Journal of Aeronautical and Space Sciences
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• v.4 no.1
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• pp.75-87
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• 2003

The primary objective of this study is to demonstrate ground-based experiment for the attitude control of spacecraft. A two-axis rotational simulator with a flexible ann is constructed with on-off air thrusters as actuators. The simulator is also equipped with payload pointing capability by simultaneous thruster and DC servo motor actuation. The azimuth angle is controlled by on-off thruster command while the payload elevation angle is controlled by a servo-motor. A thruster modulation technique PWM(Pulse Width Modulation) employing a time-optimal switching function plus integral error control is proposed. An optical camera is used for the purpose of pointing as well as on-board rate sensor calibration. Attitude control performance based upon the new closed-loop control law is demonstrated by ground experiment. The modified switching function turns out to be effective with improved pointing performance under external disturbance. The rate sensor calibration technique by Kalman Filter algorithm led to reduction of attitude error caused by the bias in the rate sensor output.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.562-567
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• 2016

Morphing wing which has a configuration optimized to flight speed and condition is faced to a lot of barriers to be overcome such as actuator technique, structural mechanization technique, flexible skin material, control law, and so on. As the first step for developing a morphing wing with rapid response, we designed and fabricated the morphing airfoil using a SMA(shape memory alloy) wire actuator and torsional bias springs. The design concept of the morphing airfoil was verified through operation test. The measured results show that the flap deflects smoothly and fast.

• Journal of Integrative Natural Science
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• v.2 no.2
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• pp.55-58
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• 2009

A ligand-receptor docking program is an indispensible tool in modern pharmaceutical design. An accurate prediction of small molecular docking pose to a receptor is essential in drug design as well as molecular recognition. An effective docking program requires the ability to locate a correct binding pose in a surprisingly complex conformational space. However, there is an inherent difficulty to predict correct binding pose. The odds are more demanding than finding a needle in a haystack. This mainly comes from the flexibility of both ligand and receptor. Because the searching space to consider is so vast, receptor rigidity has been often applied in docking programs. Even nowadays the receptor may not be considered to be fully flexible although there have been some progress in search algorithm. Improving the efficiency of searching algorithm is still in great demand to explore other applications areas with inherently flexible ligand and/or receptor. In addition to classical search algorithms such as molecular dynamics, Monte Carlo, genetic algorithm and simulated annealing, rather recent algorithms such as tabu search, stochastic tunneling, particle swarm optimizations were also found to be effective. A good search algorithm would require a good balance between exploration and exploitation. It would be a good strategy to combine algorithms already developed. This composite algorithms can be more effective than an individual search algorithms.

• Structural Engineering and Mechanics
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• v.55 no.4
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• pp.719-742
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• 2015

This paper dealt the free vibration analysis of thick truncated conical composite sandwich shells with transversely flexible cores and simply supported boundary conditions based on a new improved and enhanced higher order sandwich shell theory. Geometries were used in the present work for the consideration of different radii curvatures of the face sheets and the core was unique. The coupled governing partial differential equations were derived by the Hamilton's principle. The in-plane circumferential and axial stresses of the core were considered in the new enhanced model. The first order shear deformation theory was used for the inner and outer composite face sheets and for the core, a polynomial description of the displacement fields was assumed based on the second Frostig's model. The effects of types of boundary conditions, conical angles, length to radius ratio, core to shell thickness ratio and core radius to shell thickness ratio on the free vibration analysis of truncated conical composite sandwich shells were also studied. Numerical results are presented and compared with the latest results found in literature. Also, the results were validated with those derived by ABAQUS FE code.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.1
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• pp.128-134
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• 2014

With the development of Information Communication Technology and a way of solving problems such as productivity improvement, advanced working attitude, greenhouse gas reduction, low birth rate, aged problem, etc., the need of smart work is increasing. Getting out of legacy working types that are limited in time and space, the flexible seat system at a smart work center that supports the smart working environment is proposed. However, the seat choice based on employee's emotional judgement may cause the decline of forming cooperative space and mutual communication because of the scattered seat arrangement between employees. This paper proposed a seat recommendation method for the mutual cooperation at a smart work center. The method is based on a work similarity of employees. A prototype system also implemented to show the feasibility.

• Journal of the Korea Furniture Society
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• v.23 no.4
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• pp.342-354
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• 2012

This study aimed at acknowledging characteristics of space usage and suggesting orientation of space planning and furniture designing that meet various residents' demands correlating with residential area, furniture and family members by doing fact finding of volume of the furniture in medium/small sized apartment. The contents of the study are "experience of functional remodeling," "a number of bedrooms correlating with a number of family" and "furniture arrangement of each space and characteristics of space utilization" based on forty six cases. Followings are results of the study. 1) It was acknowledged that the function of space relating to family members largely depends on furniture arrangement correlating with age of children. It is needed that flexible planning of residential area to meets growing children and various family demands. 2) Functional remodeling requires furniture rearrangement attended with the remodeling. Thus, it is required that ideas in more simple and efficient furniture designing and consideration of construction environment embracing that ideas. 3) It can be acknowledged that the most demanding matter to enjoy satisfied and comfortable life in residential area is the matter of storage area. It is also understandable that the matter can be worse by time going by and the change of living pattern. Therefore, it is required that the consideration of enough storage area compatible with its function of the room and the planning of built-in furniture for storage.

• Korean Journal of Head & Neck Oncology
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• v.28 no.2
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• pp.114-117
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• 2012

Background and Objectives : To assure the surgical completeness of the gasless endoscopic thyroidectomy via single incision axillary approach using flexible videoscope which provide wide angle and working space, we compared single incision axillary approach and axillo-areolar approach by means of clinical, surgical outcomes. Materials and Methods : From March 2011 to July 2012, 24 patients who had underwent endoscopic thyroidectomy via transaxillary approach were enrolled. Of total, 17 patients underwent single incision axillary approach(group I) and the other 7 underwent axillo-areolar approach(group II). Results : Patient demographics, surgical indications were similar between the two groups. The operating time(group I 144.6min, group II 153.6 min ; p=.29), blood loss(group I : 55.4cc, group II : 35.7cc : p=.64), hospital stay(group I : 4.2days, group II : 4.4 days ; p=.65) were similar in the two groups. Overall, two patients in group I(2/17, 11.8%) experienced postoperative complications, including one hematoma and one seroma. Due to narrow working space, one patient was change to axillo-areolar approach during single incision axillary approach with $30^{\circ}$ rigid endoscope. Conclusion：Single incision axillary approach is safe and effective similar to other endoscopic thyroidectomy methods using flexible videoscope. Different with $30^{\circ}$ rigid endoscope, 10-mm flexible videoscope can put inside the axillary inicision site in different axis with endoscopic instruments. This difference in endoscopic axis help to prevent crash with endoscopic instrument.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.209-220
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• 1998

The stability problem of steady motion of a rigid body with multi-elastic appendages and multi-liquid-filled cavities, in the presence of no external forces or torque, is considered in this paper. The flexible appendages are modeled as the clamped -free-free-free rectangular plates, or/and as the discrete mass- spring sub-system. The motion of liquid in every single ellipsoidal cavity is modeled as the uniform vortex motion with a finite number of degrees of freedom. Assuming that stationary holonomic constraints imposed on the body allow its rotation about a spatially fixed axis, the equation of motion for such a systematic configuration can be very complex. It consists of a set of ordinary differential equations for the motion of the rigid body, the uniform rotation of the contained liquids, the motion of discrete elastic parts, and a set of partial differential equations for the elastic appendages supplemented by appropriate initial and boundary conditions. In addition, for such a hybrid system, under suitable assumptions, their equations of motion have four types of first integrals, i.e., energy and area, Helmholtz' constancy of liquid - vortexes, and the constant of the Poisson equation of motion. Chetaev's effective method for constructing Liapunov functions in the form of a set of first integrals of the equations of the perturbed motion is employed to investigate the sufficient stability conditions of steady motions of the complete system in the sense of Liapunov, i.e., with respect to the variables determining the motion of the solid body and to some quantities which define integrally the motion of flexible appendages. These sufficient conditions take into account the vortexes of the contained liquids, the vibration of the flexible components, and coupling among the liquid-elasticity solid.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.3
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• pp.185-195
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• 2021

The flapping-wing micro air vehicle (FW-MAV) in this study utilizes the cambered wings made of quite flexible material. Similar to the flying creatures, the present cambered wing uses three different materials at its leading edge, vein, and membrane. And it is constrained in various conditions. Since passive rotation uses the flexible nature of the wing, it is important to select an appropriate material for a wing. A three-dimensional fluid-structure interaction solver is developed for a realistic modeling of the cambered wing. Then a parametric study is conducted to evaluate the aerodynamic performance in terms of the elastic modulus of leading edge and vein. Consequently, the elastic modulus plays a key role in enhancing the aerodynamic performance of FW-MAVs.