• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06a
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• pp.139-156
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• 1996

The phase field model is becoming the model of choice for the theoretical study of the morphologies of crystals growth from the melt. This model provides an alternative approach to the solution of the classical (sharp interface) model of solidification by introducing a new variable, the phase field, Ø, to identify the phase. The variable Ø takes on constant values in the bulk phases and makes a continuous transition between these values over a thin transition layer that plays the role of the classically sharp interface. This results in Ø being governed by a new partial differential equation(in addition to the PDE's that govern the classical fields, such as temperature and composition) that guarantees (in the asymptotic limit of a suitably thin transition layer) that the appropriate boundary conditions at the crystal-melt interface are satisfied. Thus, one can proceed to solve coupled PDE's without the necessity of explicitly tracking the interface (free boundary) that would be necessary to solve the classical (sharp interface) model. Recent advances in supercomputing and algorithms now enable generation of interesting and valuable results that display most of the fundamental solidification phenomena and processes that are observed experimentally. These include morphological instability, solute trapping, cellular growth, dendritic growth (with anisotropic sidebranching, tip splitting, and coupling to periodic forcing), coarsening, recalescence, eutectic growth, faceting, and texture development. This talk will focus on the fundamental basis of the phase field model in terms of irreversible thermodynamics as well as it computational limitations and prognosis for future improvement. This work is supported by the National Science Foundation under grant DMR 9211276

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.121-126
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• 2000

Metal/Ceramic structures have many attractive properties, with great potential for applications that demand high stiffness, as well as chemical and biological stability, thermal and electrical insulation. They are currently in use for mechanical and thermal protection in cutting tool and engine parts. With all their great advantage, ceramics suffer from one major problem they are brittle, and are especially susceptible to cracking from surface contacts. Delamination at the interfaces with adjacent layers is a particularly disturbing problem, and can cause premature failure of a composite system. so determination of adhesive properties of coating is one of the most important problems for the extension of the use of coated materials. In this work, mechanical characteristics of Interface of ceramic/Metal composites are evaluated by means of hardness test, indentation test apparent interfacial toughness and bonding strength test. The interface indentation test provides a relation between the applied load(P) and the length of the crack(a) created at the interface between the coating and the substrate.

• Advanced Composite Materials
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• v.17 no.1
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• pp.75-87
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• 2008

Aerospace structural applications, along with high performance marine and automotive applications, require high-strength efficiency, which can be achieved using metal matrix composites (MMCs). Rotating components, such as jet-engine blades and gas turbine parts, require materials that maximize strength efficiency and metallurgical stability at elevated temperatures. Titanium matrix composites (TMCs) are well suited in such applications, since they offer an enhanced resistance to temperature effects as well as corrosion resistance, in addition to optimum strength efficiency. The overall behavior of the composite system largly depends on the properties of the interface between fiber and matrix. Characterization of the fiber.matrix interface at operating temperatures is therefore essential for the developemt of these materials. The fiber fragmentation test shows good reproducibility of results in determining interface properties. This paper deals with the evaluation of fiber fragmentation characteristics in TMCs at elevated temperature and the results are compared with tests at ambient temperature. It was observed that tensile testing at $650^{\circ}C$ of single-fiber TMCs led to limited fiber fragmentation behavior. This indicates that the load transfer from the matrix to the fiber occurs due to interfacial friction, arising predominantly from mechanical clamping of the fiber by radial compressive residual and Poisson stresses. The present work also demonstrates that composite processing conditions can significantly affect the nature of the fiber.matrix interface and the resulting fragmentation of the fiber.

• JSTS:Journal of Semiconductor Technology and Science
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• v.10 no.3
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• pp.203-212
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• 2010

In this paper, we present an analytical model for the first eigen energy level ($E_0$) of the carriers in the inversion layer in present generation MOSFETs, having ultrathin gate oxides and high substrate doping concentrations. Commonly used approaches to evaluate $E_0$ make either or both of the following two assumptions: one is that the barrier height at the oxide-semiconductor interface is infinite (with the consequence that the wave function at this interface is forced to zero), while the other is the triangular potential well approximation within the semiconductor (resulting in a constant electric field throughout the semiconductor, equal to the surface electric field). Obviously, both these assumptions are wrong, however, in order to correctly account for these two effects, one needs to solve Schrodinger and Poisson equations simultaneously, with the approach turning numerical and computationally intensive. In this work, we have derived a closed-form analytical expression for $E_0$, with due considerations for both the assumptions mentioned above. In order to account for the finite barrier height at the oxide-semiconductor interface, we have used the asymptotic approximations of the Airy function integrals to find the wave functions at the oxide and the semiconductor. Then, by applying the boundary condition at the oxide-semiconductor interface, we developed the model for $E_0$. With regard to the second assumption, we proposed the inclusion of a fitting parameter in the wellknown effective electric field model. The results matched very well with those obtained from Li's model. Another unique contribution of this work is to explicitly account for the finite oxide-semiconductor barrier height, which none of the reported works considered.

• The KIPS Transactions:PartD
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• v.15D no.5
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• pp.691-698
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• 2008

Web designers generally use a story board, a site map, a flow chart or the combination of these for representing web sites. But these methods are difficult to represent the entire architecture of a web site, and may be not adaptive for describing the detail flow of web pages. To solve these problems to some degree, there were works using EMFG(Extended Mark Flow Graph) recently. However the conventional EMFG representation method is not adaptive to represent the dynamic interface of web sites because that cover only the static parts of a web site. Internet utilization is rapidly growing in our life and we cannot imagine the worlds of work, study and business without internet. And web sites recently have not only more complex and various architecture but also web pages containing the dynamic interface. Therefore we propose the representation method of these web sites - for example, a web site containing varying pages with time and varying page status or contents with mouse operations - using EMFG. We expect our work to be help the design and maintenance of web sites.

• Design Convergence Study
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• v.16 no.5
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• pp.177-190
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• 2017

This research aims to suggest a multimodal non-touch gesture interface design to improve the usability of 3D sculpting task. The task and procedure of design sculpting of users were analyzed across multiple circumstances from the physical sculpting to computer software. The optimal body posture, design process, work environment, gesture-task relationship, the combination of natural hand gesture and arm movement of designers were defined. The preliminary non-touch 3D S/W were also observed and natural gesture interaction, visual metaphor of UI and affordance for behavior guide were also designed. The prototype of gesture based 3D sculpting system were developed for validation of intuitiveness and learnability in comparison to the current S/W. The suggested gestures were proved with higher performance as a result in terms of understandability, memorability and error rate. Result of the research showed that the gesture interface design for productivity system should reflect the natural experience of users in previous work domain and provide appropriate visual - behavioral metaphor.

• Proceedings of the ESK Conference
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• 1995.10a
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• pp.46-55
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• 1995

The multimedia documents becomes the most natural user interface for CSCW(Conputer Supported Cooperative Work) in distributed environment. The objective of this study is to propose a multimedia document architecture and to develop a system that can manage it well. The new architecture is for revisable documents and is the basic layer for hypermedia documents. A good document architecture for CSCW must support pointing, marking, and editing over a part of documents. The user views, version control, and full- content search are also desirable features. In this paper, we discuss the basic concept of a new document architecture for CSCW. We also present the user interfaces for spatio-temporal compositions of multimedia documents.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.640-642
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• 1999

Recent work within the DNP work group has resulted in the proposal, DNP 3.0, as the informative interface for distribution automation systems. This proposed standard embodies the generic principles developed and used within generic protocol. This paper describes a compliance test procedure specifically for Distribution Automation System, practical experience.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.182-187
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• 2001

This study deals with CARS (Computer Aided ROMUM System) which is a computer version of ROMUM (RObot Modularization of the Unit Motion). ROMUM was a method developed by the concept of modularization of the unit motion of robots. Because CARS is a computer assisted method of menu-driven type for human interface, this method can be easily applied for analyzing the work motion and measuring the execution time of robots. Therefore, it will be helpful for reducing the analysis effort and time of robot work.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.677-685
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• 2012

Recently, wireless multi-networking technology has been studied for supporting multi-interface in mobile node. As the related work, in the IETF NetExt WG, the extension of Proxy Mobile IPv6 protocol for supporting flow mobility is actively on going in discussion. PMIPv6 protocol supports simultaneous access through the multi-interface in a mobile node and inter-technology handover between multiple interfaces. However, this protocol can not support flow mobility. Thus, in this paper, when a mobile node connects to PMIPv6 domain through multi-interface, as a way to support flow mobility, the design of logical interface and Home Network Prefix change scheme based on logical interface are proposed, We show that the proposed scheme can perform flow mobility service without end-to-end disconnection in PMIPv6 domain.