• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.19 no.9
• /
• pp.950-959
• /
• 2009

Liquid fluctuation called sloshing within liquid-storage tank gives rise to the significant effect on the dynamic stability of tank. This liquid sloshing can be effectively suppressed by installing baffles within the tank, and the suppression effect depends strongly on the design parameters of baffle like the baffle configuration. The present study is concerned with the parametric evaluation of the sloshing suppression effect for the CNG-storage tank, a next generation liquefied fuel for vehicles, to the major design parameters of baffle, such as the baffle configuration, the installation angle and height, the hole size of baffle. The coupled FEM-FVM analysis was employed to effectively reflect the interaction between the interior liquid flow and the tank elastic deformation.

• Journal of architectural history
• /
• v.14 no.1 s.41
• /
• pp.7-19
• /
• 2005

The purpose of this paper is the study on the piazza plan of basilica S. Pietro. The results of study are as follows: 1. The piazza of the basilica S. Pietro was planned in relation to building-piazza-symbol of interior piazza-street as city planning characteristic of Baroque and architectural characteristic of elliptical piazza form. 2. The function of piazza of basilica S. Pietro was planned for religious meeting of a grand scale than a piazza for the common run of people. 3. In general, the disposition, ground, elevation and section plan of the piazza of basilica S. Pietro was planned by principle of spatial and formal composition, according to axis, symmetry, proportion, division and contrast. 4. The location, scale, shape of piazza for disposition and ground plan of the piazza of basilica S. Pietro was basically decided by not only elements of Basilica building, Vatican Palace, Street and Walls of surroundings with axis of the Basilica building, but Fountain and Obelisk as existing constituent elements. 5. The elevation of the piazza of basilica S. Pietro was composed of boundary that was enclosed from wall of trapezoid piazza and gallery of elliptical piazza with equal height as symmetry. And the section plan was planned to approach into the Basilica through slope and stairs of gentle angle, utilizing of existing land form.

• Journal of Power Electronics
• /
• v.2 no.3
• /
• pp.220-229
• /
• 2002

In this paper, maximum efficiency operation of two types of permanent magnet synchronous motor drives, namely; surface type permanent magnet synchronous machine (SPMSM) and interior type permanent magnet synchronous motor(IPMSM), are investigated. The efficiency of both drives is maximized by minimizing copper and iron losses. Loss minimization is implemented using flux weakening. A neural network controller (NNC) is designed for each drive, to achieve loss minimization at difffrent speeds and load torque values. Data for training the NNC are obtained through off-line simulations of SPMSM and IPMSM at difffrent operating conditions. Accuracy and fast response of each NNC is proved by applying sudden changes in speed and load and tracking the UC output. The drives'efHciency obtained by flux weakening is compared with the efficiency obtained when setting the d-axis current component to zero, while varying the angle of advance "$\vartheta$" of the PWM inverter supplying the PMSM drive. Equal efficiencies are obtained at diffErent values of $\vartheta$, derived to be function of speed and load torque. A NN is also designed, and trained to vary $\vartheta$ following the derived control law. The accuracy and fast response of the NN controller is also proved.so proved.

• KIEAE Journal
• /
• v.8 no.1
• /
• pp.37-44
• /
• 2008

Though they have advantages in terms of aesthetic in modern architecture, however, rectangular-shaped towers causes being short of natural light due to deep interior space. There are compromised attempts to take advantages of each building shape selectively. As a result, we now witness the advent of Y-shaped, T-shaped, V-shaped and ㅈ-shaped buildings on the market. The mutative type of apartment houses usually faces southwest or southeast, which has lot of daylighting availability but anyhow, the proportion of the apartment houses which have a full south aspect. The need to verify the potential of daylighting in new building-block shapes exists. At the same time, the expansion of balcony area was legalized and thus, a visual buffer area does not exist any more. All-glass window wall on apartment houses without a balcony produces pretty harmful area with direct sunbeam. Recently, the refurbished version of conventional windows has been developed for the purposed of minimizing energy loss occurred around windows. This research initialized a series of research to deal with almost all on window wall for apartment houses. First of all, huge amount of already-designed examples of apartment houses have been analyzed in terms of floor plan, elevation, orientation and glazing materials.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.20 no.5
• /
• pp.402-409
• /
• 2015

This paper proposes a novel rotor position error calculation method for high-frequency signal-injected sensorless control. The rotor position error using the conventional modulation method can be only measured up to ${\pm}45^{\circ}$. In addition, when the rotor position estimation error is not sufficiently small, the small angle approximation in no longer valid. To overcome these problems, this study introduces a new rotor position error calculation method using the rotating matrix. In this study, the position error measurement range of the proposed method is extended from ${\pm}45^{\circ}$ to ${\pm}90^{\circ}$. The linearity between the real rotor position error and the estimated error is maintained by nearly $90^{\circ}$. These features of the proposed method improve the performance of the sensorless control. The validity of the proposed method is verified by simulations and experiments.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.7 no.4
• /
• pp.566-576
• /
• 1995

A Computational code has been developed in order to design axial fans by the numerical optimization techniques incorporated with flow analysis code solving three-dimensional Navier-Stokes equation. The steepest descent method and the conjugate gradient method are used to look for the search direction in the design space, and the golden section method is used for one-dimensional search. To solve the constrained optimization problem, sequential unconstrained minimization technique, SUMT, is used with imposed quadratic extended interior penalty functions. In the optimization of two-dimensional cascade design, the ratio of drag coefficient to lift coefficient is minimized by the design variables such as maximum thickness, maximum ordinate of camber and chord wise position of maximum ordinate. In the application of this numerical optimization technique to the design of an axial fan, the efficiency is maximized by the design variables related to the sweep angle distributed by quadratic function along the hub to tip of fan.

• Journal of Korean Association for Spatial Structures
• /
• v.17 no.2
• /
• pp.43-51
• /
• 2017

The demand for skyscrapers is increasing worldwide. Until now, various lateral resistance structures have been used for lateral displacement control of high-rise buildings. An outrigger damper system has been introduced recently to improve lateral dynamic response control performance further. However, a study of outrigger damper system is yet to be sufficiently investigated. In this study, time history analysis was performed to investigate the control performance of an outrigger damper system of high-rise building under eccentric loading. To do this, an actual scale 3-dimensional tall building model with an outrigger damper system was prepared. The control performance of the outrigger damper system was evaluated by varying stiffness and damping values. On the top floor torsional angle response to the earthquake load, was greatly affected by damping value. And the displacement response was affected greatly by the stiffness value and damping value of damper system. In conclusion, it is necessary to select the proper damping and stiffness values of the outrigger damper system.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.3
• /
• pp.451-457
• /
• 2009

Most of objects in computer graphics may be represented by a form of mesh. The exact computation of vertex normal vectors is essential for user to apply a variety of geometric operations to the mesh and get more realistic rendering results. Most of the previous algorithms used a weight which resembles a local geometric property of a vertex of a mesh such as the interior angle, the area, and so on. In this paper, we propose an efficient algorithm for computing the normal vector of a vertex in meshes. Our method uses the conformal mapping which resembles synthetically the local geometric properties, and the mean value coordinates which may smoothly represent a relationship with the adjacent vertices. It may be confirmed by experiment that the normal vector of our algorithm is more exact than that of the previous methods.

• Structural Engineering and Mechanics
• /
• v.59 no.5
• /
• pp.933-950
• /
• 2016

Decks, interior beams, edge beams and girders are the parts of a steel floor system. If the deck is optimized without considering beam optimization, finding best result is simple. However, a deck with higher cost may increase the composite action of the beams and decrease the beam cost reducing the total cost. Also different number of floor divisions can improve the total floor cost. Increasing beam capacity by using castellated beams is other efficient method to save the costs. In this study, floor optimization is performed and these three issues are discussed. Floor division number and deck sections are some of the variables. Also for each beam, profile section of the beam, beam cutting depth, cutting angle, spacing between holes and number of filled holes at the ends of castellated beams are other variables. Constraints include the application of stress, stability, deflection and vibration limitations according to the load and resistance factor (LRFD) design. Objective function is the total cost of the floor consisting of the steel profile cost, cutting and welding cost, concrete cost, steel deck cost, shear stud cost and construction costs. Optimization is performed by enhanced colliding body optimization (ECBO), Results show that using castellated beams, selecting a deck with higher price and considering different number of floor divisions can decrease the total cost of the floor.

• Wind and Structures
• /
• v.32 no.3
• /
• pp.179-191
• /
• 2021

A series of wind tunnel tests, including 1:50 sectional model tests, 1:50 free-standing bridge tower tests and 1:70 full-bridge aeroelastic model tests were carried out to systematically investigate the aerodynamic performance of the Hong Kong-Zhuhai-Macao Bridge (HZMB). The test result indicates that there are three wind-resistant safety issues the HZMB encounters, including unacceptable low flutter critical wind speed, vertical vortex-induced vibration (VIV) of the main girder and galloping of the bridge tower in across-wind direction. Wind-induced vibration of HZMB can be effectively suppressed by the application of aerodynamic and mechanical measures. Acceptable flutter critical wind speed is achieved by optimizing the main girder form (before: large cantilever steel box girder, after: streamlined steel box girder) and cable type (before: central cable, after: double cable); The installations of wind fairing, guide plates and increasing structural damping are proved to be useful in suppressing the VIV of the HZMB; The galloping can be effectively suppressed by optimizing the interior angle on the windward side of the bridge tower. The present works provide scientific basis and guidance for wind resistance design of the HZMB.