• Proceedings of the KIEE Conference
• /
• 1989.07a
• /
• pp.44-47
• /
• 1989

In this paper, We analyzed the End Effect of Single-sided Linear Induction Motor by combination of Finite Element Method in Active region and 0- 1 order Boundary Element Method in Entry, Exit region.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1997.04a
• /
• pp.423-427
• /
• 1997

Recently, distributed piezoelectric actuators have drawn attention due to their potential applicability within smart structures. Because they serve not only as active components but also passive components, it is difficult to estimate their characteristics accurately. In this study a finite element method based on layerwise theory has been formulated to analyze the characteristics of the distributed piezoelectric actuators. The present method has the capability to describe more refined strain distribution and more realistic boundary conditions.

• Structural Engineering and Mechanics
• /
• v.39 no.3
• /
• pp.339-360
• /
• 2011

In the h-type adaptive analysis, when an element is refined or subdivided, new nodes are added. Among them are the transition nodes which are the corner nodes of the new elements formed by subdivision and, simultaneously, the mid-side nodes of the adjacent non-subdivided elements. To secure displacement compatibility, the slave-node approach in which the DOFs of a transition node are constrained by those of the adjacent nodes had been used. Alternatively, transition elements which possess the transition nodes as active mid-side/-face nodes can be used. For C0 plate analyses, the conventional slave-node constraints and the previously derived ANS transition elements are implemented. In both implementations, the four-node element is the ANS element. With reference to the predictions of the transition elements, the slave-node approach not only delivers erroneous results but also fails the patch test. In this paper, the patch test failure is resolved by developing a set of new constraints with which the slave-node approach surpasses the transition-element approach. The accuracy of the slave-node approach is further improved by developing a hybrid four-node element in which the assumed moment and shear force modes are in strict equilibrium.

• Journal of KSNVE
• /
• v.10 no.2
• /
• pp.361-366
• /
• 2000

In this paper, a new finite annular plate element is developed, which considers the effects of the slight deviation from a perfect axisymmetry. It is assumed that, when a local deviation is introduced to an axisymmetric plate, the natural modes are separated into the symmetric and asymmetric modes. The proposed method is very efficient because a few elements are demanded and lots of active degrees of freedom are reduced in comparison with commercial numerical analysis programs. In addition, when the deviation is small enough. It is more accurate than the result of using usual plate elements of commercial FEM programs.

• Journal of Environmental Science International
• /
• v.25 no.9
• /
• pp.1213-1222
• /
• 2016

Given the growing attention to nature and health in modern society, this study considered the role of a waterscape facility as a key element in a landscape's influence on users' physiological and psychological responses. The subjects were 28 university students, and the collected data included systolic and diastolic blood pressure, salivary amylase concentration, semantic differential (SD) scales, and profile of mood states (POMS). As compared to a space without any waterscape element (Type G), relaxation in a space with a waterscape element (Type W) was found to significantly reduce of systolic and diastolic blood pressure and salivary amylase concentration. The SD scale and POMS findings showed that Type W evoked active, bright, dynamic, free, vital, interesting, and cheerful images and improved mood states by enhancing vigor while inhibiting depressive feelings. These findings indicate waterscape facilities can improves users' mood states and may enhance their health.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.6 no.6
• /
• pp.891-896
• /
• 2002

In this paper, a new voltage-controlled tunable integrator for low-voltage applications is proposed. The proposed active element is composed of the CMOS complementary cascode circuit which can extend transconductance of an element. Therefore, the unity gain frequency which is determined transcon-ductance is increased than that of the conventional element. And then these results are verified by the $0.25{\mu}m$ CMOS n-well parameter HSPICE simulation. As a result, the gain and the unity gain frequency are 42dB and 200MHz respectively in the element on 2V supply voltage. And power dissipation of the designed circuit is 0.32mW.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.446-451
• /
• 2003

This paper presents some examples of active control of flow-induced vibration using piezoelectric actuators. The flutter phenomenon, which is the dynamic instability of structure due to mutual interaction among inertia, stiffness, and aerodynamic forces, may cause catastrophic structural failure, and therefore the active flutter suppression is one of the main objectives of the aeroelastic control. Active flutter control has been numerically and experimentally studied for swept-back lifting surfaces using piezoelectric actuation. A finite element method, a panel aerodynamic method, and the minimum state space realization are involved in the development of the governing equation, which is efficiently used for the analysis of the system and design of control laws with modern control framework. The active control suppressed flow-induced vibrations and extended the flutter speed around by 10%. Another representative flow-induced vibration phenomenon is the oscillation of blunt bodies due to the vortex shedding. In general, it is quite difficult to set up the numerical model because of the strong non-linearity of the vortex shedding structure. Therefore, we applied adaptive positive position feedback controller, which requires no pre-determined model of the plant, and successfully suppressed the flow-induced vibration.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.8
• /
• pp.665-675
• /
• 2016

With the development of active phased array radar technology in recent years, active phased array antennas, which digitally combine signals received from subarray units using dozens of digital receiver, have been developed. The beam characteristics are greatly affected by the shape of the subarray structure as well as the weight of subarray in digital beamforming. So in this paper, the method to generate subarray structures by using recursive element exchanging method and the method to optimize subarray structures that can minimize sidelobes of operating beams are proposed. Additionally it presents the result to find the optimized subarray structure to minimize the maximum sidelobe of monopulse beam and pencil multi-beam respectively or simultaneously which are commonly used for digital beamforming by applying the algorithm propsed in this paper.

• The korean journal of orthodontics
• /
• v.31 no.3 s.86
• /
• pp.335-346
• /
• 2001

The purpose of this study was to investigate the ideal clinical torque(In the SWA rectangular wire, the torque by the angle between the plane part and twisted part to move the tooth) of the orthodontic rectangular wire which produce the proper labiolingual movement of the single tooth during finishing stage of the orthodontic treatment. The clinical torque is the sum of the play and the active torque which generates the moment at the bracket. The play is calculated by the formula and the active torque is calculated by the computer aided three-dimensional finite element method. The finite element model was consist of the three brackets which formed a row and 3 kinds of orthodontic rectangular wire(stainless steel, TMA, NiTi) which inserted in brackets. Both sides of the model were twisted and the moment generated in the center bracket was calculated. The sizes of seven wires which were used commonly were .016'X.022', .017'X.022', .017'X.025', .018'X.025', .019'X.025', .020'X.025', .021'X.025'. In 018' bracket, 016'X.022', .017'X.022', .017'X.025' wires were inserted and in 022' bracket, all the sizes of wires except .016'X.022' were inserted and tested. The following conclusions could be drawn from this study. 1. The moments generated on the same size of the wires by the same active torque were equal regardless of the bracket slot size. 2. The moments were increased with the size of the wires. The moment generated on the .021'X.025' wire was about 1.75 times as large as that on the .016'X.022' wire regardless of the material. 3. The moments were increased in the order of the NiTi, TMA stainless steel. The moment of the TMA wire was 0.35 times as small as that of the stainless steel wire and the moment of the NiTi was0.16 times as small as that of the stainless steel wire. 4. The moment was decreased as the interbracket distance was increased. 5. To get a desired moment with the specific size and material of the wire on the specific bracket slot, the formula and the results were displayed.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.22 no.5
• /
• pp.87-92
• /
• 2022

In this paper, a study was conducted on the design of an array element that can be applied to the AESA radar for seeker. An antenna for application to AESA radar should choose an optimal radiation element to be applied to an array antenna in order to secure electronical beam steering characteristics, and consider beam steering characteristics when designing. In particular, in order to satisfy the wide-angle beam steering characteristics, the wide-angle impedance matching technique should be used to minimize the scan blindness region that may occur during wide-angle steering. As such, securing the stability of system operation is becoming an important design consideration for AESA radar. In this paper, WAIM is applied to the end of the radiation element to improve the characteristics of the radiation element applied to the AESA radar antenna device, and the change in the performance of the active reflection coefficient, which is a stable operation index of the system, is reviewed. The final performance result verified the validity of the proposed method by mathematically synthesizing the simulation data.