• Restorative Dentistry and Endodontics
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• v.45 no.2
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• pp.22.1-22.10
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• 2020

Objectives: This study investigated the influence of glide path size and operating kinetics on the time to reach the working length and the fracture resistance of Twisted File (TF) and Endostar E3 files. Materials and Methods: A total of 120 mandibular single-rooted premolars were selected. Two methods of kinetic motion (TF adaptive and continuous rotary motion) and file systems (TF and Endostar E3) were employed. The files were used in root canals prepared to apical glide path sizes of 15, 20, and 25. The time taken to reach the working length and the number of canals used before the instrument deformed or fractured were noted. Fractured instruments were examined with scanning electron microscopy. Results: The TF system took significantly more time to reach the working length than the Endostar E3 system. Both systems required significantly more time to reach the working length at the size 15 glide path than at sizes 20 and 25. A greater number of TFs than Endostar E3 files exhibited deformation, and a higher incidence of instrument deformation was observed in adaptive than in continuous rotary motion; more deformation was also observed with the size 15 glide path. One TF was fractured while undergoing adaptive motion. Conclusions: No significant difference was observed between continuous rotary and adaptive motion. The TF system and adaptive motion were associated with a higher incidence of deformation and fracture. Apical glide path sizes of 20 and 25 required significantly less time to reach the working length than size 15.

• Wind and Structures
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• v.5 no.2_3_4
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• pp.379-392
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• 2002

Numerical flow computations around an aeroelastic 3D square cylinder immersed in the turbulent boundary layer are shown. Present computational code can be characterized by three numerical aspects which are 1) the method of artificial compressibility is adopted for the incompressible flow computations, 2) the domain decomposition technique is used to get better grid point distributions, and 3) to achieve the conservation law both in time and space when the flow is computed a with moving and transformed grid, the time derivatives of metrics are evaluated using the time-and-space volume. To provide time-dependant inflow boundary conditions satisfying prescribed time-averaged velocity profiles, a convenient way for generating inflow turbulence is proposed. The square cylinder is modeled as a 4-lumped-mass system and it vibrates with two-degree of freedom of heaving motion. Those blocks which surround the cylinder are deformed according to the cylinder's motion. Vigorous oscillations occur as the vortex shedding frequency approaches cylinder's natural frequencies.

• Selected Papers of The Society of Naval Architects of Korea
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• v.2 no.1
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• pp.29-46
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• 1994

In this paper, the effect of a skirt deformation on the responses of an Air Cushion Vehicle in waves is investigated. The air in the bag and plenum chamber is assumed to be compressible and to have a uniform pressure distribution in each volume. The free surface deformation is determined in the framework of a linear potential theory by replacing the cushion pressure with the pressure patch which is oscillating and translating uniformly. And the bag-finger skirt assumed to be deformed due to the pressure disturbance while its surface area remained constant. The restoring force and moment due to the deformation of bag-finger skirt from equilibrium shape is incorporated with the equations of heave and pitch motions. The numerical results of motion responses due to various ratios of the bag and cushion pressure or bag-to-finger depth ratios are shown.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.83-90
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• 1999

This paper presents a method of seismic analysis for a cylindrical liquid storage structure on horizontally layered half-space considering the effects of the interior fluid and exterior soil medium in the frequency domain. the horizontal and rocking motions of the structures are included in this study. The fluid motion is expressed in terms of analytical velocity potential function which can be obtained by solving the boundary value problem including the sloshing behavior of the fluid as well as deformed configuration of the structure. The effect of the fluid is included in the equation of motion as the impulsive added mass and a frequency-dependent convective added mass along the nodes on the wetted boundary with structure. The soil medium is presented using the 3-D axisymmetric finite elements and dynamic infinite elements. The present method can be applied to the structures embedded in ground as well as on ground since it models the soil medium directly as well as the structure. For the purpose of vertification dynamci characteristics of a tank on homogeneous half-space is analyzed. Comparison of the present results with those by others shows good agreement.

• Structural Engineering and Mechanics
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• v.41 no.6
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• pp.735-750
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• 2012

This paper presents a comparison between two different procedures to deal with the geometric nonlinear analysis of space trusses, considering its structural stability aspects. The first nonlinear formulation, called positional, uses nodal positions rather than nodal displacements to describe the finite elements kinematics. The strains are computed directly from the proposed position concept, using a Cartesian coordinate system fixed in space. The second formulation, called corotational, is based on the explicit separation between rigid body motion and deformed motion. The numerical examples demonstrate the performances and the convergence of the responses for both analyzed formulations. Two numerical examples were compared, including a lattice beam with postcritical behavior. Despite the two completely different approaches to deal with the geometrical nonlinear problem, the results present good agreement.

• Archives of Reconstructive Microsurgery
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• v.10 no.2
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• pp.111-117
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• 2001

Introduction : The Functional muscle transfer is used to reconstruct the injuried muscle and paralysis of the shoulder. Especially transfer of the trapezius has been the treatment of choice but it has disadvantages of inadequate function and deformed contour, and instability of humeral head in case of acromion resection. We report an operation for shoulder reconstruction after wide resection of malignant fibrous histiocytoma, using rotational latissimus dorsi flap and review the operation method and clinical outcome. Materials and Methods : A patient, 53 year old, with malignant fibrous histiocytoma in the acromioclavicular joint area had been underwent wide excision, including the deltoid, clavicular head of pectoralis major, part of trapezius, lateral 1/3 of clavicle and acromion including scapular spine. The rotational latissimus dorsi flap with its neurovascular pedicle was dissected and then placed over the resected area and transfer of muscle attached at coracoid process was done to achieve stability of the humeral head. The range of motion of the shoulder and test of muscle power were evaluated for functional outcome. Total follow-up period is 2 years 11 months. Results : At last follow-up, the range of motion of the shoulder is abduction $90^{\circ}$, flexion $90^{\circ}$, internal rotation $40^{\circ}$, external rotation $50^{\circ}$ and the muscle power is 4 grade in all direction and then we obtained good functional results. There are no complications such as instability or subluxation of the humeral head and deformed contour and he is a disease-free survival state. Conclusions : The transfered latissimus dorsi flap provides adequate lever arm and stabilization and covering of the humeral head by sufficient muscle volume and width. This procedure can be useful not only for the paralysed deltoid reconstruction but also for use in reconstructive surgery after wide resection of the shoulder for malignant tumor.

• Steel and Composite Structures
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• v.25 no.4
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• pp.403-413
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• 2017

The fabric braided braking hose that delivers the driver's braking force to brake cylinder undergoes the large deformation cyclic motion according to the steering and bump/rebound motions of vehicle. The cyclic large deformation of braking hose may give rise to two critical problems: the interference with other adjacent vehicle parts and the micro cracking stemming from the fatigue damage accumulation. Hence, both the hose deformation and the fatigue damage become the critical issue in the design of braking hose. In this context, this paper introduces a multi-objective optimization method for minimizing the both quantities. The total length of hose and the helix angles of fabric braided composite layers are chosen for the design variables, and the maximum hose deformation and the critical fatigue life cycle are defined by the individual single objective functions. The trade-off between two single objective functions is made by introducing the weighting factors. The proposed optimization method is validated and the improvement of initial hose design is examined through the benchmark simulation. Furthermore, the dependence of optimum solutions on the weighting factors is also investigated.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.791-793
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• 2016

In the development of various types of sensor technology, the general users smartphone, the environment is increased, which can be seen in contact with the movement recognition device, such as a console game machine (Nintendo Wii), an increase in the user needs of the action recognition-based input device there is a tendency to have. Mouse existing behavior recognition, attached to the outside, is mounted in the form of mouse button is deformed, the left mouse was the role of the right button and a wheel, an acceleration sensor (or a gyro sensor) inside to, plays the role of a mouse cursor, is to manufacture a compact, there is a difficulty in operating the button, to apply a motion recognition technology is used to operate recognition technology only pointing cursor is limited. Therefore, in this paper, using a MEMS-based motion-les Koguni tion sensor (Motion Recognition Sensor), to recognize the behavior of the two points of the human body (thumb and forefinger), to generate the motion data, and this to the foundation, compared to the pre-determined matching table (moving and mouse button events cursor), and generates a control signal by determining, were studied the generated control signal input device of the computer wirelessly transmitting.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11C
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• pp.940-947
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• 2010

Motion Compensated Frame Interpolation(MCFI) has been used to reduce motion jerkiness for dynamic scenes and motion blurriness for LCD-panel display as post processing for high quality display. However, MCFI that directly uses the motion information often suffers from annoying artifacts such as blockiness, ghost effects, and deformed structures. So in this paper, we propose a novel edge-based adaptively weighted vector median filter as post-processing. At first, the proposed method generates an edge direction map through a sobel mask and a weighted maximum frequent filter. And then, outlier MVs are removed by average of angle difference and replaced by a median MV of $3{\times}3$ window. Finally, weighted vector median filter adjusts the weighting values based on edge direction derived from spatial coherence between the edge direction continuity and motion vector. The results show that the performance of PSNR and SSIM are higher up to 0.5 ~ 1 dB and 0.4 ~ 0.8 %, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.1 s.178
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• pp.129-135
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• 2006

In this study, a two-axis ultra-precision stage driven by piezoelectric elements is presented. The stage has a flexure-type parallel linear guide mechanism consisting of quad-symmetric simple parallel linear springs and quad-symmetric double compound linear springs. While the simple parallel linear springs guide the linear motion of a moving plate in the stage, the double compound linear springs follow the motion of the simple parallel linear spring as well as compensate the parasitic motions caused by the simple parallel linear springs. The linear springs are designed by rectangular beam type flexures that are deformed by bending deflection rather than axial extension, because the axial extension is smaller than the bending deflection at the same force. The designed guide mechanism is analyzed by finite element method(FEM). Then two-axis parallel linear stage is implemented by the linear guide mechanism combined with piezoelectric elements and capacitance type displacement sensors. It is shown that the manufactured ultra-precision stage achieves 3 nm of resolution in x- and y-axis within 30 ${\mu}m$ of operating range.