• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.413-418
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• 2012

A modified VIStA (Vortex Inertial Staged Air) burner has been developed and applied to a once-through type boiler. The secondary air is supplied through a swirler instead of nozzles, which stabilizes the flame and reduces carbon monoxide (CO) emissions. However, the modification increases the emission of nitrogen oxides (NOx). To balance emissions of the two pollutants, a divided flame was adopted. An air damper was installed to control the distribution of air to each combustion chamber, and three types of flame dividers were studied. The effects of the air-fuel ratio and combustion load on the NOx formation were investigated. The divided flame was found to reduce the NOx emission up to 25%, while keeping the CO to less than 10 ppm.

• Steel and Composite Structures
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• v.20 no.4
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• pp.801-812
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• 2016

In an actual design, none of the structures with shear behaviors will be designed for torsional moments. Any failure or damages to roofs, infills, shear walls, and braces caused by an earthquake, will inevitably result in relocation of center of mass and rigidity of the structure. With these changes, the dynamic characteristics of structure could be changed during an earthquake at any moment. The main objective of this paper is to obtain the relationship between time-varying eccentricity of load and corner lateral displacement. In this study, various methods have been used to determine the structural response for time-varying lateral corner displacement. As will be seen below, some of the structural calculation methods result in a significant deviation from the actual results, although these methods include the interaction effects of modes. Controlling the lateral displacement of structure can be performed in different ways such as, passive dampers, friction dampers, semi-active systems including the MR damper and active Systems. Selecting and locating these control systems is very important to bring the maximum safety with minimum cost into the structure. According to this study will be show the relation between the corner lateral displacements of structure and time-varying eccentricity by different kind of methods during an earthquake. This study will show that the response of the structure at the corners due to an earthquake can be very destructive and because of changing the eccentricity of load, calculating the maximum possible response of system can be carried out by this method. Finally, some kind of systems must be used for controlling these displacements. The results shows that, the CQC, DSC and exact methods is comply each other but the results of Vanmark method is not comfortable for these kind of buildings.

• Journal of KIISE:Software and Applications
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• v.32 no.8
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• pp.769-780
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• 2005

This paper addresses a novel application of meshes to analyzing the deformation patterns of 2D signals. The proposed mesh is distinguished form the previous models in that it includes simulated charges in each node that interact with external charges comprising an input pattern. Therelaxation of the mesh given an input is carried out by any of the well-known numerical integration techniques. The result of the relaxation is a deformed mesh. This Paper provides four criterion functions for measuring the pattern deformation. A set of trained meshes was created from the simple average of target patterns. Experimental results show that these measures, although highly intuitive, are not good enough to capture the amount and characteristics of pattern deformation. If more sophisticated measures are found and incorporated into the relaxation process, we expect that a better and high-performance mesh framework is realized.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.6
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• pp.65-71
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• 2008

A one-dimensional site response analysis program (KODSAP) was developed using cyclic soil behavior model by using the modified parallel IWAN model. The model is able to predict the cyclic hardening and degradation of soil through the adjustment of the internal slip stresses of its elements beyond the cyclic threshold, and satisfies Bauschinger's effect and the Masing rule in terms of its own behavior characteristics. The program (KODSAP) used the direct integration method in the time domain. The elasticity of the base rock was considered as a viscous damper boundary condition. The effects of cyclic hardening or degradation of soil on site response analysis were evaluated through parametric studies. Three types of analyses were performed to compare the effect of analysis and cyclic parameter on site response. The first type was equivalent linear analysis, the second was nonlinear analysis, and a third was nonlinear analysis using the cyclic hardening or degradation model.

• Journal of Korean Association for Spatial Structures
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• v.8 no.4
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• pp.91-100
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• 2008

In this study, the vibration control performance of high-rise building structures connected by a sky-bridge has been investigated. The philosophy of vibration control using sky-bridges is to allow structures with different dynamic characteristics to exert control forces upon one another through sky-bridges to reduce the overall responses of the system. The the high-rise building structure connected by sky-bridge with 49 and 42 stories was used in this study to investigate the displacement, acceleration, reaction of bearings and stress of sky-bridge by analytical methods. To this end, historical earthquakes, an artificial earthquake and wind force time histories obtained from wind tunnel tests were used. Based on the analytial results, the use of sky-bridge can be effective in reducing the structural responses of high-rise buildings against wind and seismic loads.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.399-404
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• 2005

In this paper, An immunized PID(I-PID) controller based on cell mediated immune response is proposed to improve the control performance of the controller with PID scheme. And it is applied to the vibration of the building structure in the port with active damper systems. The immune system of organism in the real body regulates the antibody and T-cells to protect the attack from the foreign materials which are virus, germ cell, and other antigens. It has similar characteristics that are the adaptation and robustness to overcome disturbances and to control the plant of engineering application. At firstly, we build a model of the T-cell regulated immune response mechanism. We have also designed an I-PID controller focusing on the T-cell regulated immune response of biological immune system. Finally, we show that some computer simulations of the vibraton control for the building structure system with wind force excitation. These results for the proposed method also show that is has performance than other conventional controller design method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.5
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• pp.819-827
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• 1997

In this paper, a new modeling of a fine actuator for an optical pick-up has been proposed and multiobjective optimization of the actuator has been performed. The fine actuator is constituted of the bobbin which is supported by wire suspension, the coils which wind around the bobbin, and the magnets which cause the magnetic flux. If current flows in the coils, magnetic force is so produced as to be balanced with spring force of wire, so the bobbin is pisitioned. In this model the transfer function from input voltage to output displacementof bobbin has been obtained so that we can describe this integrated system with electromagnetic and mechanical parts. Wire suspension is regarded as a continuous Euler beam, damper as distributed viscous damping, and bobbin as a rigid body which can move up- and down- ward motion only. According to the model, the high frequency dynamic characteristics of the fine actuator can be known and the effect of damping can be investigated while the conventional second order model cannot. In multiobjective optimization, two objective functions have been chosen to maximize the fundamental frequency and the sensitivity with respect to the input voltage of the actuator so that Pareto's optimal solutions have been obtained using .epsilon.-constraint method. These objective functions will satisfy the trends which will enhance the access speed and reduce the tracking error in the optical pick-up technology of next generation. In the result of optimization, we obtain the designs of the optical pick-up fine actuator which has high speed, high sensitivity and low resonant peak. Furthermore, we offer the relation between two object functions so that the designer can make easy choice.

• Fire Science and Engineering
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• v.24 no.6
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• pp.153-159
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• 2010

In this study, we confirmed the fact that air egress velocity of pressure differential system installed at vestibule of smokeproof stairway in domestic high-rise building becomes back-flow to stair-lobby at upper vestibule. Rather it do not back-flow to the livingroom. when fire occur and the door opens to escape from fire zone. so we carry out actual and computational fluid dynamics measurement. In the case upward 45 gradient of supply damper's blade, The simulation results that air flow of upper vestible is steady but back-flow phenomenon occurred at the bottom. However, in the case of $4m^2$, direction of the flow was ideal to living room. If a vestibule’s area is smaller, it must be designed and built according to performance-based design.

• Journal of the Korea Concrete Institute
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• v.27 no.6
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• pp.625-632
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• 2015

In this study, a comparative analysis have been conducted to examine seismic reinforcement effect of a school building that is designed with a CBD (Channel Beam Damper) system supported by H-frame with existing non-seismic RC frame. As a result of experiment, seismic reinforcement specimen with CBD system showed hysteretic characteristics of a large ellipse with great energy dissipation ability and increased strength and stiffness, while non-seismic design specimen showed rapid reduction in strength and brittle shear failure at top and bottom of the left and right column. In addition, comparing the stiffness reduction between the two specimens, CBD system was effective in preventing the reduction of stiffness. Energy dissipation ability of specimen reinforced by CBD system was about 4.0 times higher than the non-reinforced specimen. Such enhancement in energy dissipation ability could be considered as the result of improved strength and deformation for further application in designing of seismic reinforcement.

• The Journal of the Acoustical Society of Korea
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• v.11 no.4
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• pp.5-13
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• 1992

The vibration of a vehicle, which is caused by and transmitted from the engine, has significant effect on the ride comfort and the dynamic characteristics of the engine mount system has direct influence on the vibration and noise of the vehicle. This paper examines the body shake caused by the engine excitation force on engine key-off of a jeep by experiment and computer simulation using a general purpose mechanical system program, DADS. The computer simulation model consists of the engine, body including frame, and front and rear axles and each axle has right and left tires. The force element between body and suspension is modeled as a combination of suspension spring and damper, and the unsprung mass has roll and pitch motion. The body shake obtained from experiment was compared with the result of computer simulation. Parametric study of the body shake on engine key-off is performed with changing the stiffness of engine mount rubber, the engine mount installation angle and position of engine mounts by using the verified computer simulation model.