• Journal of Magnetics
• /
• v.16 no.4
• /
• pp.427-430
• /
• 2011

The rolled steels for welded structure applied tensile stress have been examined by means of magnetic Barkhausen noise (MBN) method and of a physical parameter obtained from a hysteresis loop. The behaviors of MBN parameters and coercive force with tensile stress were discussed in relation to microstructure changes. There is no change in MBN parameters and coercive force below yield strength. The coercive force rises rapidly with tensile stress above yield strength. On the other hand, the rms voltage and the peak in averaged rms voltage take a maximum around yield strength and then decreases. The magnetomotive force at peak in the averaged rms voltage shows a minimum around yield strength. These phenomena are attributed to the combined effects of cell texture and dislocation density. In addition, the behaviors of MBN parameters around yield strength may be reflected by the localized changes in strain field due to the formation of dislocation tangles.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.12
• /
• pp.2915-2925
• /
• 1993

A finite element program using degenerated shell element was developed to solve the geometric, material and combined nonlinear behaviors of composite laminated plates. The total Lagrangian method was implemented for geometric nonlinear analysis. The material nonlinear behavior was analyzed by considering the matrix degradation due to the progressive failure in the matrix and matrix-fiber interface after initial failure. The results of the geometric nonlinear analyses showed good agreements with the other exact and numerical solutions. The results of the combined nonlinear analyses considered both geometric and material nonlinear behaviors were compared to the experiments in which a concentrated force was applied to the center of the square laminated plate with clamped four edges.

• Journal of Advanced Marine Engineering and Technology
• /
• v.23 no.4
• /
• pp.514-522
• /
• 1999

The laser-induced plasma affects greatly on the results of welding process. moreover selective evaporation loss of alloying elements leads to change in chemical composition of weld metal as well as the mechanical properties of welded joint. this study was undertaken to obtain a fundamental knowledge of pulsed laser welding phenomena especially evaporation mechanism of different aluminum alloys. The intensities of molecular spectra of AlO and MgO were different each other depeding on the power density of a laser beam Under the low power density condition the MgO band spectrum was predominant in intensity while the AlO spectra became much stronger with an increase in the power density. These behaviors have been attributed to the difference in evaporation phenomena of Al and Mg metals with different boiling points and latent heats of vaporization. The time-averaged plasma temperature and electron number density were determined by spectroscopic methods and consequently the obtained temperature was $3,280{\pm}150K$ and the electron number density was $1.85{\times}10^{19}\;l/m^3$.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.10b
• /
• pp.1313-1318
• /
• 2000

Crack behaviors at the downstream face of the concrete gravity dam were studied considering influence of the wintertime air temperature. It is assumed that inside area of 15m away from the dam surface in which temperature is presumed to be $15^{\circ}C$ is not affected from the annual air temperature variation. Water temperature at the upstream face and air temperature at the other faces were considered as outer boundary conditions to get temperature distribution inside of the dam using ADINA-T. These temperature distributions were transferred to FRANC2D to obtain equivalent stress intensity factors and crack propagation paths. Results obtained from changing initial crack locations and direction, air temperatures, and water levels were discussed. And crack behaviors at the upstream face were studied partly.

• Proceedings of the KIEE Conference
• /
• 2001.07d
• /
• pp.2464-2466
• /
• 2001

In this paper, a behavior-based fuzzy control of mobile robots for autonomous navigation is presented. Behaviors of mobile robots are divided into two categories: reactive behavior and purposeful behavior, which are incompatible with each other. The former is reaction performed in terms of the sensory data and the latter is action for achieving the goal. The presented method generates appropriate control inputs to the robot to trade-off between the reactive and purposeful behaviors using fuzzy inferences. The method is applied to an synchro-drive type mobile robot and shown to be useful for autonomous robot navigation by providing simulation results.

• Journal of the Korean Home Economics Association
• /
• v.41 no.7
• /
• pp.91-106
• /
• 2003

Multiple features of infant day-care are explored, including age of entry, quantity, quality and stability of day-care. And relative contribution of day-care and family factors on maternal behaviors are examined. Data were gathered from 299 mothers who have infants aged under 36 months using self-report questionnaires. Results show that more than 40% infants enter day-care before 6 months of their life and about 85% of infants have far more than 30 hours of care a week. Half of the infants experience different day-care arrangements more than once. Compared to the other types of day-care, frequency of day-care arrangement change and quality of care are highest in private child-care centers. A series of Hierarchical regression results reveal that quality of day care is negatively related to mothers' control behavior whereas positively related to mothers' responsive behavior. But in general, family and child characteristics play a greater role in mothers' parenting behaviors than infant day-care characteristics.

• Proceedings of the KIEE Conference
• /
• 1999.07g
• /
• pp.3030-3032
• /
• 1999

This Paper proposes a fuzzy algorithm for cooperative behaviors of multiple autonomous mobile robots. Each robot makes decision of his behavior based on the information obtained by infrared sensors to measure the position and velocities of other robots. The effectiveness of the proposed algorithm is shown by some computer simulation where a group of mobile robots encircles with equi-interval.

• The Pure and Applied Mathematics
• /
• v.16 no.4
• /
• pp.427-441
• /
• 2009

The method of Lattice Dynamical System is used to establish a global model on an infinite chain of many local markets interacting each other through a diffusion of prices between them. This global model extends the Walrasian evolutionary cobweb model in an independent single local market to the global market evolution. We assume that each local market has linear decreasing demands and quadratic supplies with naive predictors, and investigate the stationary behaviors of global price dynamics and show that their dynamics are conjugate to those of $H{\acute{e}}non$ maps and hence can exhibit complicated behaviors such as period-doubling bifurcations, chaos, and homoclic orbits etc.

• The Pure and Applied Mathematics
• /
• v.17 no.1
• /
• pp.93-106
• /
• 2010

We employ the methods of Lattice Dynamical System to establish a global model extending the Walrasian evolutionary cobweb model in an independent single local market to the global market evolution over an infinite chain of many local markets with interaction of each other through a diffusion of prices between them. For brevity of the model, we assume linear decreasing demands and logistic supplies with naive predictors, and investigate the traveling wave behaviors of global price dynamics and show that their dynamics are conjugate to those of H$\acute{e}$non maps and hence can exhibit complicated behaviors such as period-doubling bifurcations, chaos, and homoclic orbits etc.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.4
• /
• pp.394-401
• /
• 2004

In this study the mechanical behaviors of fiber metal laminates(FMLs) such as ARALL, GLARE and CARE which are recently developed as new structural materials and known to have excellent fatigue resistant characteristics while with relatively low densities compared to the conventional aluminum materials, are considered through the classical lamination theory. The mechanical properties such as elastic moduli, thermal expansion coefficients and hygro-thermally induced residual stresses in the fiber metal laminates are obtained and compared each other. Also, carpet plots of effective elastic moduli, Poisson's ratio and the thermal expansion coefficient for GLARE FML are plotted.