• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.2
• /
• pp.339-341
• /
• 2012

The high Tc superconductor of YBCO system with the nominal composition of precursor was prepared from mixed powders of $Y_2O_3$, $BaCO_3$, CuO and $TiO_2$ by the thermal pyrolysis method. The effect of $TiO_2$ doping to Y based ceramics superconductors fabricated by the thermal pyrolysis reaction, to investigate the effect of the dopant on the superconductivity. The voltage appearing across the field-cooled HTS sample increased with external magnetic field. The improvement of critical current property as well as the mechanical property is important for the application. The improvement of the critical current can be achieved by forming the nano size defect working as a flux pining center inside the superconductor. We simply added $TiO_2$ to starting materials to dope $TiO_2$ and observed an increase in the trapped field and the critical current density up to at least 5 wt % $TiO_2$. The $TiO_2$ was converted to fine $BaTiO_3$ particles which were trapped in YBCO matrix during the sintering process. We observed a peak effect of Jc that can be attributed to $TiO_2$ doping and results suggest that introducing a proper amount of pinning centers can significantly enhance current density.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.3 s.174
• /
• pp.761-768
• /
• 2000

In order to investigate how the fatigue damage effects on the critical properties of superconductor, a fatigue test at room temperature and an Ic measurement test at 4.2K were carried out in this study, respectively, using a 9 strand Cu-Ni/NbTi/Cu composite cable. Through the fatigue test of a 9 strand Cu-NUNbTi/Cu composite cable, a conventional S-N curve was plotted even though there was a possibility of fretting among strands. It was found that the maximum stress corresponding to the inflection point on the S-N curve obtained was nearly the same value as the yielding strength of cable obtained from the static tensile test. However, the effect of cabling in multi-strands superconducting cable on the fatigue strength was not noticeable. The critical current(Ic) measurement was carried out at 4.2K in a NbTi strand out of the fatigued cable. It showed a degradation of lc at high stress amplitude regions over 380NTa, and the degradation became significant as the applied stress amplitude increased.

• Steel and Composite Structures
• /
• v.14 no.3
• /
• pp.295-312
• /
• 2013

In this paper, a simplified approach based on critical temperature for fire resistance design of steel-concrete composite beams is proposed. The method for determining the critical temperature and fire protection of the composite beams is developed on the basis of load-bearing limit state method employed in current Chinese Technical Code for Fire safety of Steel Structure in Buildings. Parameters affecting the critical temperature of the composite beams are analysed. The results show that at a definite load level, section shape of steel beams, material properties, effective width of concrete slab and concrete property model have little influence on the critical temperature of composite beams. However, the fire duration and depth of concrete slab have significant influence on the critical temperature. The critical temperatures for commonly used composite beams, at various depth of concrete and fire duration, are given to provide a reference for engineers. The validity of the practical approach for predicting the critical temperature of the composite beams is conducted by comparing the prediction of a composite beam with the results from some fire design codes and full scale fire resistance tests on the composite beam.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.943-944
• /
• 2006

This paper discusses the modeling of Three-Level converter according to critical characterist.

• Journal of Korean Society for Quality Management
• /
• v.32 no.3
• /
• pp.216-233
• /
• 2004

The real estate management includes not only the brokerage, property management, development, investment and consulting which are related to real estate handling, but also the human resources who deal with the real estate business. The level of management quality of Korean real estate business is rather poor. This paper deals with management innovation of real estate management using Six Sigma methodology The main focus of this Paper is to develop strategy Planning, and is to select critical success factors for each strategy to make an advanced management system for real estate business. This paper is a case study, and the target company for this innovation is ERA-Korea Company. Seven strategies are proposed, and for each strategy several critical success factors are suggested. Through this case study, the authors hope that a management quality model for real estate business is proposed, and an improved management method can be adopted in the other real estate companies.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1999.04a
• /
• pp.11-18
• /
• 1999

For the proper design of a slender compression member, the exact determination of the elastic critical load is crucial, In the cases of non-prismatic compression members, the determinations of the elastic critical load cannot be usually expressed in closed forms. h this paper, the non-symmetrically tapered compression members with arbitrary boundary conditions me analysed by using the finite element method to determine the elastic critical load. The main parameters considered in the numerical analysis are the In Parameter, $\alpha$ and the sectional property parameter, m. To generaliza the unmerical analysis, of the computed results for each sectional parameter, m are presented in algebraic equations, which agrees fairy well with those by F.E.M in most cases.

• Nuclear Engineering and Technology
• /
• v.52 no.3
• /
• pp.560-567
• /
• 2020

The complexity of safety critical systems of Nuclear Power Plant continues to increase rapidly due its transition from analog to digital systems. It has thus become progressively more imperative to model these systems prior to their implementation in order to meet the high performance, safety and reliability requirements. Timed Petri Nets (TPNs) have been widely used to model such systems for non-functional analysis. The paper presents a novel methodology for the analysis of the performance metrics using PN modeling. The paper uses the isomorphism property of the TPNs and the Markov chains for the performance analysis of the safety critical systems. The presented methodology has been validated on a Shutdown System of a Nuclear Power Plant.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1999.10a
• /
• pp.421-428
• /
• 1999

The elastic critical load of a slender compression member plays an important role when the proper design of that member is required. For the tapered compression members, however, there are cases when the conventional neutral equililbrium or energy method can't be applied to the determination of critical loads of those members. In this paper, finite element method is applied to the approximate determination of the symmetrically tapered bars. Here in this paper, the bars are assumed to take sinusoidally changing shapes along their axes. The parameters considered in this study are taper parameter, $\alpha$ and the sectional property parameter, m. The computed results by finite element method are represented in the forms of algebraic equations. Regression technique is employed to determine the coefficients of algebraic equations. The critical loads estimated by the proposed algebraic equations coincide fairly well with those of finite element method.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2000.10a
• /
• pp.299-306
• /
• 2000

The elastic critical load of a slender compression member plays an important role when the proper design of that member is required. For tapered compression members, however, there are cases when the conventional neutral equilibrium or energy method can't be applied to the determination of critical loads. In this paper, the finite element method is applied to the approximate determination of the linearly tapered members. In this paper, the bars are assumed to be tapered linearly along their axes. The parameters considered in this study are taper parameter, α and the sectional property parameter, m. The member ends are either hinged or fixed. The computed results using the finite element method are represented in the forms of algebraic equations. The regression technique is employed to determine the coefficients of the algebraic equations. Critical loads estimated by the proposed algebraic equations coincide flirty well with those employing the finite element method.

• Journal of Korean Library and Information Science Society
• /
• v.20
• /
• pp.455-470
• /
• 1993

In recent years, the intellectual property rights (IPR) are increasingly becoming trade goods and the subject of international trade negotiations. During the past decades, intellectual properties earned critical importance for economic development in both developed and developing countries. Developed countries, headed by the United States, that recognize the economic value of the IPR in the world market are aggressively seeking for universal protection of IPR throughout the world. Intellectual properties have unique qualities that distinguish them from other tangible goods. Most importantly, they are public goods created on the basis of knowledge and information accumulated throughout human history and shared by different cultures. However, there is a growing tendency that the quality of public goods are being etched away as the property concept in IPR expands. In this paper, I discuss how copyright and patent laws incorporated the concept of property right as natural right to one's intellectual creations in early formation of the laws in Europe. I argue that copyright law and patent law are the historical products resulting from political, economic, and ideological factors interacting in a certain society. A history of copyright and patent points to that the intellectual property rights as natural lights of authors and inventors as argued by developed countries in international disputes, are not universal, but unique historical products. Copyright and patent laws have been shaped and developed as regulatory measures by governments to promote and control industries by providing authors and inventors with monopoly incentives. Since property right was used as a regulatory device it was restricted. This is to enhance the distribution of knowledge and information rather than to ensure the property right as an absolute right.