• Journal of Power System Engineering
• /
• v.11 no.2
• /
• pp.44-50
• /
• 2007

The oxidation behavior of commercial pure titanium is investigated in the temperature range of $727^{\circ}C{\sim}950^{\circ}C$ in mixed gases. The weight change is measured by TGA during oxidation in mixed gases. The oxidation behavior indicated by weight gain or the growth of oxide layer is based on the linear rate law at high temperatures. The structure of the oxide scale formed during oxidation is analysed by optical microscopy, electron probe microanalyzer, scanning electron microscope and x-ray diffraction. Oxide scales have a $TiO_2$ structure, and are constituted with multi-layered or two layered porous external one and a dense internal one. Ti-O solid solution region is formed at the interface of metal and scale layer. The formation of oxide scale is influenced by the oxidation temperature, time, crystal structure and the condition of atmosphere.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.3
• /
• pp.285-297
• /
• 2016

In this paper, a centralized mmWave-based multi-spot beam cellular system architecture having such a base station equipped with a plurality of beam-forming antennas, multi-layered dynamic cell configuration method as one of key concepts of this system operation and a mobility management method based on it are introduced. To estimate the performance of new system, system simulation was performed under the ideal environment without blockage. These results show the possibility that system capacity can be dramatically increased and mobility performance similar to the existing cellular system may be achieved.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.7C
• /
• pp.644-651
• /
• 2007

In multiple antenna systems, vertical Bell Labs Layered Space-Time (V-BLAST) systems enable very high throughput by nulling and cancelling at each layer detection. In this paper, we propose a V-BLAST system which combines with signal space diversity technique. The benefit of the signal space diversity is that we can obtain an additional gain without extra bandwidth and power expansion by applying inphase/quadrature interleaving and the constellation rotation. Through simulation results, it is shown that the performance of the proposed system is less than 0.5dB away from the ideal upper bound.

• Korean Management Science Review
• /
• v.16 no.1
• /
• pp.187-201
• /
• 1999

In this paper, we propose a multi-layered architecture of workflow management systems based on CORBA (Common Object Request Broker Architecture). The system aims to support product development processes in distributed environment. Many companies have started to adopt workflow management systems to manage and support their business processes. However, there are many problems in direct application of those systems to product development environments. These mainly resulted from the dynamic features of product development processes. It is strongly required to support dynamic processes as well as static and procedural ones in an integrated and consistent manner. To meet these requirements, a basic workflow management system has been developed as the core component of the integrated architecture. This performs the basic functions of workflow management system. Second, a dynamic workflow management system based on a bidding mechanism has been developed to manage processes that cannot be easily defined or are likely to be modified, Finally, an SGML workflow management system, which is the third layer in the architecture, has been developed to manage documents processing workflows by integration SGML documents contents and process information into the structured SGML document.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.03a
• /
• pp.533-540
• /
• 2002

Recently, geogrid reinforcement has been applied tn the subgrade of the roadway and the railway on the compressible layered soil, and the relevant reserch on the reinforcing mechanism has been performed. In this study, mechanics of geogrid reinforcement and the parameters for the improvement of bearing capacity are evaluated and presented based on the case histories of the field load test on the geogrid-reinforced layered subgrade

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2000.10a
• /
• pp.226-232
• /
• 2000

The design of agricultural facilities is the consistent activities, which systematically analyze all the actual conditions, design the unit structures, and improve the faming environment through efficient organization of the unit facility. The design of agricultural facilities is composed of site study, preliminary design, primary design, and detail design. Integrated design system can manage and process the information created by and used in all steps of design process. Formal data models of these design activities are important conceptual steps in development of integrated design system. However, most of existing models are not available for agricultural facilities. To support efficiently developing the integrated design system of agricultural facilities, we have developed the Multi-Layered Primitive-Composite mode I through object-oriented analysis of agricultural facilities. The MPC model not only satisfies the characteristics of agricultural facility, such as variety, coupling, informal data, but also improves abilities of integrated design system such as extensibility, flexibility, and granularity. The paper presents a formal definition of the MPC model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.309-313
• /
• 2000

A structural-acoustic coupling problem involving fluid in a cavity divided with flexible walls and porous materials is investigated in this paper. In many practical problems, the use of finite elements to discretize the fluid region leads to large stiffness and mass matrices. But, since the acoustic boundary element discretization requires to put elements only on the surface of structure, the size of matrices is reduced considerably. Here, we developed a numerical analysis program for the structural-acoustic coupling problems of the multi-region cavity, using boundary elements for the fluid regions and finite elements for the structure. By considering sound transmission through layered systems placed in a cavity, the accuracy of the coupled acoustical-structural finite element model has been verified by comparing its transmission loss predictions with analytical sloutions. Example problems are included to investigate the characteristics of the multi-region structural-acoustic coupling system with porous material.

• ETRI Journal
• /
• v.30 no.6
• /
• pp.807-817
• /
• 2008

We present a low-density parity-check (LDPC)-based, threaded layered space-time-frequency system with emphasis on the iterative receiver design. First, the unbiased minimum mean-squared-error iterative-tree-search (U-MMSE-ITS) detector, which is known to be one of the most efficient multi-input multi-output (MIMO) detectors available, is improved by augmentation of the partial-length paths and by the addition of one-bit complement sequences. Compared with the U-MMSE-ITS detector, the improved detector provides better detection performance with lower complexity. Furthermore, the improved detector is robust to arbitrary MIMO channels and to any antenna configurations. Second, based on the structure of the iterative receiver, we present a low-complexity belief-propagation (BP) decoding algorithm for LDPC-codes. This BP decoder not only has low computing complexity but also converges very fast (5 iterations is sufficient). With the efficient receiver employing the improved detector and the low-complexity BP decoder, the proposed system is a promising solution to high-data-rate transmission over selective-fading channels.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2002.03a
• /
• pp.117-124
• /
• 2002

The major purpose of this study is to determine the dynamic behavior of soil-pile-structure interaction system considering the underground cavity. For the analysis, a numerical method fur ground response analysis using FE-BE coupling method is developed. The total system is divided into two parts so called far field and near field. The far field is modeled by boundary element formulation using the multi-layered dynamic fundamental solution that satisfied radiational condition of wave. And this is coupled with near field modeled by finite elements. For the verification of dynamic analysis in the frequency domain, both forced vibration analysis and free-field response analysis are performed. The behavior of soil non-linearity is considered using the equivalent linear approximation method. As a result, it is shown that the developed method can be an efficient numerical method to solve the seismic response analysis considering the underground cavity in 2D problem.

• 제어로봇시스템학회:학술대회논문집
• /
• 1992.10a
• /
• pp.236-242
• /
• 1992

Multi-layered neural networks are applied to the identification and control of nonlinear dynamical system. Traditional adaptive control techniques can only deal with linear systems or some special nonlinear systems. A scheme for combining multi-layered neural networks with model reference network techniques has the capability to learn the nonlinearity and shows the great potential for adaptive control. In many interesting cases the system can be described by a nonlinear model in which the control input appears linearly. In this paper the identification of linear and nonlinear part are performed simultaneously. The projection algorithm and the new estimation method which uses the delta rule of neural network are compared throughout the simulation. The simulation results show that the identification and adaptive control schemes suggested are practically feasible and effective.