• The Korean Journal of Physiology and Pharmacology
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• v.8 no.1
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• pp.7-15
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• 2004

Nitric oxide (NO) system has been implicated in a wide range of physiological functions in the nervous system. However, the role of NO in regulating the neural activity in the gustatory zone of nucleus tractus solitarius (NTS) has not been established. The present study was aimed to investigate the role of NO in the gustatory NTS neurons. Sprague-Dawley rats, weighing about 50 g, were used. Whole cell patch recording and immunohistochemistry were done to determine the electrophysiological characteristics of the rostral gustatory nucleus of the tractus solitaries and distribution of NO synthases (NOS). Neuronal NOS (nNOS) immunoreactivity was strongly detected along the solitary tract extending from rostral to caudal medulla. Resting membrane potentials of NTS neurons were $-49.2{\pm}2\;mV$ and action potential amplitudes were $68.5{\pm}2\;mV$ with a mean duration measured at half amplitude of $1.7{\pm}0.3\;ms$. Input resistance, determined from the response to a 150 ms, -100 pA hyperpolarizing current pulse, was $385{\pm}15\;M{\Omega}$, Superfusion of SNAP or SNP, NO donors, produced either hyperpolarization (68%), depolarization (5%), or no effect (27%). The hyperpolarization was mostly accompanied by a decrease in input resistance. The hyperpolarization caused by SNAP or SNP increased the time to initiate the first action potential, and decreased the number of action potentials elicited by current injection. SNP or SNAP also markedly decreased the number of firing neural discharges of the spontaneous NTS neural activity under zero current. Superfusion of L-NAME, a NOS inhibitor, slightly depolarized the membrane potential and increased the firing rate of NTS neurons induced by current injection. ODQ, a soluble guanylate cyclase inhibitor, ameliorated the SNAP-induced changes in membrane potential, input resistance and firing rates. 8-Br-cGMP, a non-degradable cell-permeable cGMP, hyperpolarized the membrane potential and decreased the number of action potentials. It is suggested that NO in the gustatory NTS has an inhibitory role on the neural activity of NTS through activating soluble guanylate cyclase.

• Korean Journal of Mathematics
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• v.14 no.1
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• pp.113-123
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• 2006

The arches may buckle in a symmetrical snap-through mode or in an asymmetry bifurcation mode if the load reaches a certain value. Each bifurcation curve develops as pressure increases. The governing equation is derived according to the bending theory. The balance of forces provides a nonlinear equilibrium equation. Bifurcation theory near trivial solution of the equation is developed, and the buckling pressures are investigated for various spring constants and opening angles.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.1
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• pp.13-20
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• 2005

Since High Tensile Steel has been widely used to thin plate on the steel structure and marine structure, It has increased possibility of buckling. Especially, initial deflection of ship structure is mainly caused by heat processing of welding or cutting etc. This initial deflection has negative effect to thin plate, which would incur a complicated nonlinear behavior accompanied with secondary buckling. If idealized initial deflection is considered in early marine structure design of secondary buckling, accuracy and reliability will be improved considerably. The measurement data of initial deflection from experiment is applied to finite element series analysis. For FEA(ANSYS), Applied nonlinear buckling analysis is used by Newton-Raphson method & Arc-length method included in this program.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.1
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• pp.17-26
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• 1990

A solution strategy for geometric non-linear analysis for the plane frame structures subjected to conservative and non-conservative forces is presented. By making efficient combination of the load incremental method and the displacement incremental method, this strategy can find postbuckling configuration such as snap-through and turning-back phenomena which cannot be easily found by the conventional load and displacement incrementation scheme. In the case of the analysis of the framed structure subjected to circulatory non-conservative forces, the total tangent stiffness matrix becomes unsymmetric and when calculating the incremental load and unbalanced load vector components, the direction change of the non-conservative forces is considered. Several example problems to demonstrate the feasibility of the present strategy, over ranges of deformation that are well beyond those likly to occur in practical framed structures, are given and discussed.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.176-183
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• 2004

Deployable structures are space frames consisting of straight bars that are linked together into bundle and can be deployed large, load bearing structures. Deployable structures are easy to set up, to assemble, to disassemble, to transport and to keep for the use. Also, reusability and flexibility are another important advantages for environmental matter. Since deployable structures have various advantages, they offer viable alternatives for a wide range of potential applications in the temporary construction industry as well as in the aerospace industry. The purpose of this thesis is to decide on geometrical parameters of the design through the numerical analysis and create a final configuration of deployable structures using the geometrical parameters. The Multibody Dynamic Analysis that is dealt with mechanics and aeronautics is used for the method of analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.378-385
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• 2017

This study investigated the design of a snap fit, which is widely used for fastening plastic parts. We analyzed the assembly mechanism of a lock snapfit, measured the assembly force and separation force based on the design of experiments, and derived a regression equation through an analysis of variance. The response surface methodology was also used. Polybutylene terephthalate was used to fabricate specimens, and the assembly force and separation force were measured using a micro-tensile tester. The length, width, thickness, and interference were considered as factors. A second-order regression model was used to derive the regression equation. The assembly force decreased with increasing length and width, but it increased with increasing thickness and interference. The finite element method was used to analyze the assembly mechanics. The width decreased the assembly force by increasing the ductility. The influences of the factors for low assembly force and high release force were shown to be opposite to each other. It was necessary to design a structure that minimized the assembly force while maintaining an appropriate level of separation force.

• Journal of Korean Association for Spatial Structures
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• v.23 no.2
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• pp.19-28
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• 2023

Timber structures are susceptible to moisture, contamination, and pest infestation, which can compromise their integrity and pose a significant fire hazard. Despite these drawbacks, timber's lightweight properties, eco-friendliness, and alignment with current architectural trends emphasizing sustainability make it an attractive option for construction. Moreover, timber structures offer economic benefits and provide a natural aesthetic that regulates building temperature and humidity. In recent years, timber domes have gained popularity due to their high recyclability, lightness, and improved fire resistance. Researchers are exploring hybrid timber and steel domes to enhance stability and rigidity. However, shallow dome structures still face challenges related to structural instability. This study investigates stability problems associated with timber domes, the behavior of timber and steel hybrid domes, and the impact of timber member positioning on dome stability and critical load levels. The paper analyzes unstable buckling in single-layer lattice domes using an incremental analysis method. The critical buckling load of the domes is examined based on the arrangement of timber members in the inclined and horizontal directions. The analysis shows that nodal snapping is observed in the case of a concentrated load, whereas snap-back is also observed in the case of a uniform load. Furthermore, the use of inclined timber and horizontal steel members in the lattice dome design provides adequate stability.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.272-275
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• 2005

The postbuckling analysis of composite curved panels subjected to lateral loading was conducted by a nonlinear finite clement program, ACOS. Two kinds of graphite/epoxy composite materials, URN300 and USN 125 were tested to verify the finite element analysis. High stiffness composite material, URN300 curved panels showed the critical failure prior to initial buckling. On the contrary USN 125 curved panels showd no severe damage after snap-through. In both panels, the finite element and experimental results showed good agreement.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.471-476
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• 2001

The main object of this study is to develop a reliable FEM simulation technique for stability test using ABAQUS software and to clarify the effect of base profile of a steel D&I(drawn and ironed) can on the dome reversal pressure. For the can after body making simulation, two kind of stability test, dome buckle test and axial crush test are performed. The factors studied in the base profile on the dome reversal pressure are the base diameter, the rim radius, the dome shoulder radius, the dome radius and the dome depth. Within the limits before the occurrence of normal snap-through buckling of dome, the dome reversal pressure is improved by decreasing the base diameter, increasing the dome depth or increasing the dome shoulder depth.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.10
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• pp.997-1005
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• 2010

Most motion control systems consist of a desired trajectory generator, a motion controller such as a conventional PID controller, and a plant to be controlled. The desired trajectory generator as well as the motion controller is very important to achieve a good tracking performance. Especially, if the desired trajectory is generated actively utilizing the maximum velocity, acceleration, jerk and snap as given system specifications, the tracking performance would be better. For this, we make use of the properties of convolution operator in order to generate a smooth (S-curve) trajectory satisfying the system specifications. Also, the proposed trajectory generation method is extended to more general cases with arbitrary initial and terminal conditions. In addition, the suggested trajectory generator can be easily realized for real-time implementation. Finally, the effectiveness of the suggested method is shown through numerical simulations.