• Transactions on Electrical and Electronic Materials
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• v.7 no.5
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• pp.230-234
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• 2006

One of the methods currently being investigated as a possible non-intrusive diagnostic tool for condition monitoring of power transformer and cable is the recovery voltage measurement, which will be improving the ability to detect the content of water concentration and the ageing process in the insulation system and may thus be an indicator of insulation quality and its ageing status. The polarization phenomenon was studied using RVM with oil-paper samples. In order to interpret its mechanism, the Extended Debye model was introduced. With different circuit parameters, various simulation results were gotten. Furthermore, with the test samples of different ageing condition, measurements are accomplished in the lab. On the basis of this experiment as well as theoretical analysis, correlations between polarizations and ageing were analyzed.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.140.2-140.2
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• 2016

Despite the growing interest in GeTe as a archetypal displacive ferroelectric material as well as the basis of related materials used in data-storage applications, atom-resolved study of single crystalline GeTe surface been lacking. Using low temperature scanning tunneling microscopy (STM) and spectroscopy (STS), we investigated as-cleaved and annealed surfaces of GeTe. We found that as-cleaved GeTe(111) surface is composed of at least two kinds of terraces at 78 K. While two terraces show metallic characteristics, they also exhibit distinctive I-V spectra and imaging conditions, with each being attributed to Ge-terminated, and Te-terminated surfaces respectively. GeTe(111) surfaces annealed at moderately elevated temperature introduces intricate networks of extended defect structures. We will present these data and discuss the role of vacancies in the formation of these structures.

• The Journal of the Korean dental association
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• v.49 no.5
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• pp.279-285
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• 2011

Currently there is no dental ceramic material can be used in all dental situations need to be restored. However, in view of recent clinical reports, the most viable alternative is zirconia ceramic. Clinical success of dental zirconia restorations strongly depends on proper selection of materials, accurate laboratory procedure and final cementation, which can be achievable with the correct understanding of zirconia. As dental materials, zirconia ceramics have a very bright future, because they are being used increasingly in the anterior region as implant fixtures, as well as crown and bridge restorations and implant abutments. Many dental ceramics showing poor clinical performance have been gone from the dental market. However, in terms of outstanding mechanical properties and esthetic nature, new dental materials can replace zirconia ceramics will not be available in the foreseeable future.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.2
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• pp.131-141
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• 2012

A field theoretical approach to deformation and fracture of solid-state material is outlined, and its application to diagnosis of deformational status of metal specimens is discussed. Being based on a fundamental physical principle known as local symmetry, this approach is intrinsically scale independent, and capable of describing all stages of deformation on the same theoretical foundation. This capability enables us to derive criteria that can be used to diagnose transitions from the elastic to plastic regime, and the plastic to fracturing regime. For practical applications of these criteria, an optical interferometric technique known as electronic speckle-pattern interferometry is proved to be quite powerful; it is able to visualize the criteria as a whole image of the object on a real-time basis without numerical processing. It is demonstrated that this method is able to reveal loading hysteresis as well.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.198-203
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• 1998

This study, a sub-one of comprehensive research works titled under “Rural Resources Evaluation System”, tried to verify utility/applicability of the developed model system through the case study works on 3 sample villages, Backya, Uyan and Suyu, representing the lowland, upland and seashore villages respectively. From the various surveying and collecting works including the official/statistical data collection, map analysis, insitu investigation, field survey and written material review, the original data set were obtained and manipulated into final input data for resources grading. After then, by the automatized calculation procedure of “Rural Resources Evaluation System”, score results for resources evaluation were finally produced with the total maximum score being 1,000. Through comparing works among score results of 3 case villages and between score results and areal characteristics of each case village, the applicability of the system developed in this study was well confirmed.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.11a
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• pp.170-174
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• 2003

While related with electronic commerce and supply chain management, the concept of ERP is more extended. Even information technology makes it more important to achieve company competence Automobile material industry in which there are the variety of suppliers and materials, has to relate with external information such as supply chain information in order to induct efficient ERP system. This study focuses on the induction policies of ERP system through data sharing within supply chain, and performed both case study and statistical analysis through the interviews to the suppliers of automobile materials. To the better induction of ERP through information sharing of SCM, we have to consider the needs of partner of which information sharing is being done well. This study suggests that organizational change management, business process, information technology are orderly taken into account as the analytical results.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2003.05a
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• pp.196-199
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• 2003

In a modern society, as the architectural materials have become main subject of the interior design expression, their influence on architecture is becoming substantial. There are multiple ways of using architectural materials. The aesthetic value is greatly enhanced by the fact that the architectural materials can be used to create unrestricted and new expression. The modern time is uncertain and rapidly changing. In this era of chaos and diversity, the materialism is being superseded by idealism. Speedy exchange of information among the countries with development of new technology and materials increases the possibility of new expressions. Each new material that adds new value influences on the other art as well as the architecture. These characteristics of new expressions could be viewed as having close relationship with current idealism. Therefore, the study on the expressive trend of architectural materials will provide better understanding and translation on expression of interior design. At this point, this study has a purpose in not only understanding architectural materials but also researching for the characteristics of expression on interior design with consideration of paradigmatic variation in modern times.

• Journal of the Korean Professional Engineers Association
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• v.14 no.4
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• pp.15-25
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• 1981

Electrical behaviors of the divalent silver oxide-zinc cell were analyzed for imporving capacity and keeping electrodes from passivation or sharp increases of cell internal resistance in the course of discharge. One of primary factors in relation to lowering performance can be depicted by cell internal resistance increase being created by various routes, first by insufficiency and/or the carbonation of the electrolyte, secondly by barrier blockage, thirdly by electrode passivation which are due to improper material use of wrong processing, and by gassing as fourth cause. The carbonation causes electrobyte to have impedance up as well as poor amalgamation, resulting in vigorous corrosion reaction of copper plated inner top, evolving hydrogen gas. Electrical characteristics of the cell was reviewed to elucidate relationships between the discharge capacity and the cell internal resistance.

• Tribology and Lubricants
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• v.29 no.1
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• pp.39-45
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• 2013

Magnetorheological (MR) fluid belongs to the group of smart materials. In MR fluid, iron particles in base oil form chains in the direction of the applied magnetic field, thus resulting in a variation in the stiffness and damping characteristics of the fluid. Research is being carried out on controlling the stiffness and damping characteristics as well as the tribological characteristics of the MR fluid. In this study, the friction characteristics of MR fluid have been evaluated using three types of materials and magnetic fields of different strengths. The coefficients of friction of the three types of MR fluid are measured, and the relationship between the coefficient of friction and the strength of the applied magnetic field is obtained.

• Transactions of Materials Processing
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• v.23 no.8
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• pp.475-481
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• 2014

Water quenching is one method of cooling after hot forming, which is presently being used for the manufacturing of automobile parts. The formed parts at room temperature are heated and then cooled rapidly in a water bath to produce high strength. The formed parts may undergo excessive thermal distortion during the water quench. In order to predict the distortion during water quenching, a coupled thermo-mechanical simulation is needed. In the current study, the simulation of heating and cooling of boron steel cylinders was performed. The material properties for the simulation were calculated from JMatPro, and the convective heat transfer coefficient was obtained from experimental tests. The results show that the thermal distortion and the residual stresses are well predicted by the coupled simulation.