• Journal of Korea Foundry Society
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• v.31 no.6
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• pp.366-370
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• 2011

The influence of aging treatment on the microstructure, mechanical and electrical properties of Cu-Be alloy for connector material applications was investigated. The properties of mechanical strength and electrical conductivity were found to increase with increasing aging temperature. By the way, SEM/EDS and TEM analysis exhibited that beryllides precipitation (CoBe and NiBe) with a size of 50 nm were distributed in grains. It was, therefore concluded that these beryllide precipitates improved the mechanical strength and also it was favor in increasing of electrical conductivity.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.1656-1660
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• 2006

Distributed coordination function(DCF) is the primary random access mechanism of IEEE 802.11, which is the basic protocol of wireless LAN based on the CSMA/CA protocol. It enables fast installation with minimal management and maintenance costs and is a very robust protocol for the best effort service in wireless medium. The current DCF, however, is known to be unsuitable for real-time applications such as voice message transmission. In this paper, we focus on the performance issues of IEEE 802.11 which accommodate the prioritized messages. Existing results use the initial window size and backoff window-increasing factor as tools to handle the priority of the messages. Instead, we introduce a novel scheme which chooses the backoff timer with arbitrary probabilities. By this, one can greatly reduce the backoff delay of the lower priority messages without degrading the performance of higher priority.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.241-245
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• 2003

In this paper, a microassembly system based on hybrid manipulation schemes is proposed and applied to the assembly of a photonic component. In order to achieve both high precision and dexterity in microassembly, we propose a hybrid microassembly system with sensory feedbacks of vision and force. This system consists of the distributed 6-DOF micromanipulation units, the stereo microscope, and haptic interface for the force feedback-based microassembly. A hybrid assembly method, which combines the vision-based microassembly and the scaled teleoperated microassembly with force feedback, is proposed. The feasibility of the proposed method is investigated via experimental studies for assembling micro opto-electrical components. Experimental results show that the hybrid microassembly system is feasible for applications to the assembly of photonic components in the commercial market with better flexibility and efficiency.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.12
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• pp.2061-2071
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• 2003

The macro-parametric approach, which is a method of CAD model exchange, has recently been proposed. CAD models can be exchanged in the form of a macro file, which is a sequence of modeling commands. As an event-driven commands set, the standard macro file can transfer design intents such as parameters, features and constraints. Moreover it is suitable for the network environment because the standard macro commands are open, explicit, and the data size is small. This paper introduces the concept of the macro-parametric method and proposes its representation using XML technology. Representing the macro-parametric data using XML allows managing vast amount of dynamic contents, Web-enabled distributed applications, and inherent characteristic of structure and validation.

• Structural Engineering and Mechanics
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• v.7 no.1
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• pp.95-110
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• 1999

An effective moment of inertia is developed for a rectangular, prismatic elastoplastic beam with elastic, linear-hardening material behavior. The particular solution for a beam with elastic, perfectly plastic material behavior is also presented with applications for beam bending in closed-form. Equations are presented for the direct application of the virtual work method for elastoplastic beams with concentrated and distributed loads. Comparisons are made between the virtual work method deflections and the deflections obtained by using an average effective moment of inertia over two lengths of the beam in the elastoplastic region.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.993-996
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• 1999

A mobile agent is a program which is capable of migrating autonomously from host to host in the heterogeneous network, to perform some computation on behalf of the user. Mobile agents have many advantages in the distributed computing environment. But they are likely to suffer many attacks on the security due to the mobility. In order to make use of a mobile agent in the real applications, the security issues must be addressed. We deal with the problem which is concerned with protecting a mobile agent in transit and detecting a mobile agent clone. In this paper we propose a trust center based secure mobile agent transfer protocol. This protocol transfers a mobile agent securely from host to host and detects a mobile agent clone. We further show the security of the protocol against many attacks.

• Proceedings of the IEEK Conference
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• 2000.11c
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• pp.169-172
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• 2000

Recently, the advent of World-Wide-Web(WWW) and the explosive popularity of the Internet gave birth to collaborative applications which were enabled by computers and networks as their primary media. And the progress of 3D computer graphics enabled collaborative application with 3D virtual environments or distributed virtual environments. In this paper, we explain our implementation of Share collaboration engine and Virtual Architectural Engineering 2000 (VAE2000) system which is our pilot application implemented with Share collaboration engine. And we explain problems presented by our experiments with VAE2000 system. For those problems, we design our new middle-ware system, SHINE(SHared INternet Environment). The SHINE proposes new concepts and approaches for collaboration with 3D objects in a virtual world.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.2
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• pp.10-20
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• 1994

This paper describes a design and implementation of the DFR(Document Filing and Retrieval) system. one of applications of DOAM(Distributed Office Application Model) which is the international standard in ISO(International Standards Organization). On the basis of the international standard, the DFR system is implemented on SUN workstation and PC/386 with C language, and its implementation is verified by tracing the association descriptor and primitives of service elements when its operation is tested between client and server. The result of this study shows that the DFR system can be implemented on the basis of the international standard, and makes a contribution toward the establishment of functional standards for the DFR system.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.1-10
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• 1996

Protocol specifications and service definitions for distributed open system applications are defined using ASN.1. Therefore, to implement an open system application likes MHS, it is necessary to have well defined encoding/decoding modules which translate ASN.1 protocol specifications into their transfer syntaxes. However, that work is usually tedius, time consuming, and error prone. In this paper, we designed and implemented a new ASN.1 tool set which includes a new ASN.1 run-time library, called HY BER/DER, and an enhanced ASN.1-to-C compiler, called HYASNC$^{+}$. HYASNC$^{+}$ automatically generates C language encoder/decoder stub files and heder files for basic ASN.1 types and subtypes defiend in X.208 recommandation, and all X400 MHS system macro definitions. And, we evaluated the performance of HYASNC$^{+}$ compiler and HY BER/DER run-tiem library, and tested the interoperability of ASN.1 run-time library.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.553-556
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• 2003

The objective of this study is to implement geological functions on the Internet such as the visualization, search and analysis of geological data. To improve their performance and reduce the cost during development, special concerns should be given to the dynamic integration and interoperability of them. XML Web Service technologies can be adopted and OpenGIS specifications should be considered for the integration of distributed GIS components and their interoperability. Because standard Internet protocols and XML Messages are used in the Web Service, it makes the integration among different hardware and software systems possible. OpenGIS specifications also enable users to get benefits from geographic information and services across any network, platform and application. A prototype of efficient Internet GIS applications has been suggested in this study.