• Proceedings of the KSR Conference
• /
• 1998.11a
• /
• pp.171-178
• /
• 1998

This paper proposes a new overmodulation strategy to give a better voltage utilization by tracking voltage vector along hexagon sides. This strategy enables the inverter to control both magnitude and angle of current. Therefore, the vector control using this strategy can lead to better output torque dynamics compared to the conventional slip frequency control with six-step voltage, which is widely used in the traction drive. In this strategy, the d-axis output voltage of a current controller to control the flux is conserved and the q-axis output voltage to control the torque is controlled to place the voltage vector on the hexagon boundary In case of overmodulation. The limited q-axis voltage is used for anti-windup of q-axis current controller. This paper also presents a new field weakening scheme which incorporate the proposed overmodulation strategy. In this scheme, the flux level is selected by both required current limit and the available maximum voltage along hexagon sides. The validity of the proposed overall scheme is confirmed by the computer simulations for a typical traction drive with a 210[㎾] induction motor.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.18 no.4
• /
• pp.101-116
• /
• 2016

"Athleisure" indicates a new fashion style which takes advantage of the merits of both sportswear and outdoor clothing. This fashion style produces clothing we can wear very conveniently regardless of time and place. This paper, first, surveyed the concept of athleisure and the socio-cultural background of its appearance in modern fashion, and then, analyzed the growing processes and tendencies of athleisure in various fields of fashion. The three typical characteristics of athleisure can be summarized as Non-boudary, Functionality, and Sensualirty. It is hoped that this study has provided some theoretical evidences for the athleisure which is expanding broadly but vaguely as megatrends.

• Journal of the Korean Society of Safety
• /
• v.20 no.1 s.69
• /
• pp.7-12
• /
• 2005

In heavy industrial fields such as power plant and chemical plant, it is often necessary to restore a damaged part of large machinery or structure which is installed in the hazard working place. In this paper, to evaluate the safety of plastic deformed cylindrical beam a finite element technique has been used. The variations of residual stresses on the process of damaging and restoring for surfaces and cross-sections have been examined. The results show that the maximum von Mises stresses occur outer cylinder surfaces of boundary between cylindrical beam support md cylindrical beam when deformation procedure and restoring force is applied. The maximum residual stress remains 158.6MPa in the inner wall and this value correspond to $53\%$ of yield stress then restoration procedure is finished.

• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.53-55
• /
• 2015

We study MHD wave propagation in a gravitationally stratified isothermal viscous atmosphere of the Sun, permeated by a uniform magentic field. We perform numerical simulations by launching a slow wave on the upper boundary. The driven slow wave propagates down from low-${\beta}$ to high-${\beta}$ plasma across the region where the plasma ${\beta}$ is unity. It is found that mode conversion takes place at $z{\approx}-1.8$ in the layer ${\beta}{\approx}1$. The amplitudes of horizontal and vertical velocites are smaller than those obtained in the absence of viscosity.

• Structural Engineering and Mechanics
• /
• v.15 no.1
• /
• pp.135-149
• /
• 2003

The bubble packing method is implemented for adaptive mesh generation in two and three dimensions. Bubbles on the boundary of a three-dimensional domain are controlled independently of the interior bubbles in the domain, and a modified octree technique is employed to place initial bubbles in the three-dimensional zone. Numerical comparisons are made with other mesh generation techniques to demonstrate the effectiveness of the present bubble packing scheme for two- and three-dimensional domains. It is shown that this bubble packing method provides a high quality of mesh and affordable control of mesh density as well.

• 한국연소학회:학술대회논문집
• /
• 2012.04a
• /
• pp.247-248
• /
• 2012

Unidentified self-ignitions were reported when the high-pressure hydrogen gas suddenly leaked out. This paper presents a flow visualization study to investigate the self-ignition mechanism in a test tube how the ignition process is initiated and the flame propagates with measurement of a number of pressure and light sensors installed in the tube supported the analysis of the self-ignition. The test result showed the location of the self-ignition taken place and critical static pressure at the boundary layer for self-ignition.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.2
• /
• pp.605-615
• /
• 1996

Laminar flows in which mixing and chemical reactions take place between parallel streams of reactive species are studied numerically. The governing equations for laminar flows are from two-dimensional compressible boundary-layer equations. The chemistry is a finite rate single step irreversible reaction with Arrhenius kinetics. Ignition, premixed flame, and diffusion flame regimes are found to exist in the laminar reacting mixing layer at high activation energy. At high Mach numbers, ignition occurs earlier due to the higher temperatures in the unburnt gas. In diffusion regimes, property variations affect the laminar profiles considerably and need to be included when there are large temperature differences. The maximum temperature of a laminar reacting mixing layer is almost linear with the adiabatic flame temperature at low heat release, but only weakly at high heat release.

• Proceedings of the Korean Institute of Interior Design Conference
• /
• 2001.05a
• /
• pp.82-85
• /
• 2001

The Late modem society have been changing in so complicated and diverse ways. Each unique parts of both culture and arts are interpenetrating as lowering high of u artistic boundaries lot better communication between environmental contexts in the concept of ‘intertextuality’. Contemporary Interior Design also has freed itself from a conventional boundary of field rather than stay in a single field, which is now shown to attempt a new style of design and expression style connecting itself it to other genre. So in this thesis ‘installation’does not mean a traditional field of arts but for building interior space with environmental area in extended context - place(hyper -reality ), tableau (medium) , transformation (expansion) . Contemporary Interior Design is expanding its range and enhancing its power of expression based on the installating concept and its expression style.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.11a
• /
• pp.501-508
• /
• 2000

In recent years, as lines are selected In disadvantageous region, unavoidable developments is increased. Owing to such developments. environmental problems have been occurred frequently, In excavation of tunnels especially located in close to slope, uneven stress take place to tunnel due to a topographical factor. it is used assistant methods of construction which are excavation of slope, retaining wall, ground anchor, etc for uneven stress. these assistant methods raise problems of environmental. In this study, using slit, we could make better stress state by means of inducing stress concentration in boundary of tunnel. considering a variety of slit and rock mass condition, we use numerical analysis.

• Geophysics and Geophysical Exploration
• /
• v.11 no.4
• /
• pp.318-325
• /
• 2008

Assigning an exact boundary condition is of great importance in three-dimensional (3D) magnetotelluric (MT) modeling, in which no source is considered in a computing domain. This paper presents a 3D MT modeling algorithm utilizing a Dirichlet condition for a 2D host. To compute boundary values for a model with a 2D host, we need to conduct additional 2D MT modeling. The 2D modeling consists of transverse magnetic and electric modes, which are determined from the relationship between the polarization of plane wave and the strike direction of the 2D structure. Since the 3D MT modeling algorithm solves Maxwell's equations for electric fields using the finite difference method with a staggered grid that defines electric fields along cell edges, electric fields are calculated at the same place in the 2D modeling. The algorithm developed in this study can produce reliable MT responses for a 3D model with a 2D host.