• Korean Journal of Computational Design and Engineering
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• v.17 no.2
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• pp.91-96
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• 2012

Use of casting simulation software, analyzing the reason for defect became easy. However, to create a practical solution, experienced casting expert's knowledge is always indispensable. In this study, we develop casting design automation system and the algorithm based on casting expert's knowledge, so that faster and more accurate design is enabled. Especially, to generate runner which can be shaped in numerous ways, we suggest the 'nexus' method to shape runner system.

• ETRI Journal
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• v.30 no.1
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• pp.81-88
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• 2008

The security threat posed by worms has steadily increased in recent years. This paper discusses the application of the optimal and sub-optimal Internet worm control via Pontryagin's maximum principle. To this end, a control variable representing the optimal treatment strategy for infectious hosts is introduced into the two-factor worm model. The numerical optimal control laws are implemented by the multiple shooting method and the sub-optimal solution is computed using genetic algorithms. Simulation results demonstrate the effectiveness of the proposed optimal and sub-optimal strategies. It also provides a theoretical interpretation of the practical experience that the maximum implementation of treatment in the early stage is critically important in controlling outbreaks of Internet worms. Furthermore, our results show that the proposed sub-optimal control can lead to performance close to the optimal control, but with much simpler strategies for long periods of time in practical use.

• International Journal of Control, Automation, and Systems
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• v.6 no.5
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• pp.785-791
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• 2008

This paper considers the problem of robust $H_{\infty}$ control for uncertain 2-D discrete systems in the General Model via output feedback controllers. The parameter uncertainty is assumed to be norm-bounded. The purpose is the design of output feedback controllers such that the closed-loop system is stable while satisfying a prescribed $H_{\infty}$ performance level. In terms of a linear matrix inequality, a sufficient condition for the solvability of the problem is obtained, and an explicit expression of desired output feedback controllers is given. An example is provided to demonstrate the application of the proposed method.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.217-218
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• 2011

이 논문은 SVPWM으로 구동하는 3상 2레벨 인버터에 레그-션트저항(Leg-Shunt Resistor)을 이용한 전류 검출방식의 전류 검출영역 확장 방법을 제안한다. 레그-션트 저항을 이용한 전류 검출방식은 션트저항이 인버터 아래쪽 IGBT 이미터(Emitter)단에 있기 때문에 PWM 스위칭 상태에 따라 전류 검출영역이 제한된다. 이 논문에서는 레그-션트저항 전류 검출방식의 전류 검출가능영역을 정의하고 전류 검출이 어려운 부분에서도 전류를 검출을 하는 방법을 제안한다.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.52-55
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• 2004

Digital communication networks have become a core technology in advanced building automation systems. BACnet(${\underline{B}}uilding$ ${\underline{A}}utomation$ and ${\underline{C}}ontrol$ ${\underline{net}}works$) is a standard data communication protocol designed specifically for building automation and control systems. BACnet adopts Master-Slave/Token-Passing (MS/TP) protocol as one of its field level networks. In this study, we introduce a method of implementing bandwidth allocation scheme in the MS/TP protocol. The bandwidth allocation scheme improves the capability of real-time communication of the original MS/TP protocol. The bandwidth allocation scheme introduced in this paper can be easily implemented in the existing MS/TP protocol with a slight modification. In this study, we actually developed the hardware and firmware of MS/TP module in which bandwidth allocation scheme is implemented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.4
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• pp.819-833
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• 2013

Computing global features based on local features using a bio-inspired framework has shown promising performance. However, for some tough applications with large intra-class variances, a single local feature is inadequate to represent all the attributes of the images. To integrate the complementary abilities of multiple local features, in this paper we have extended the efficacy of the bio-inspired framework, HMAX, to adapt heterogeneous features for global feature extraction. Given multiple global features, we propose an approach, designated as parameterized metric learning, for high dimensional feature fusion. The fusion parameters are solved by maximizing the canonical correlation with respect to the parameters. Experimental results show that our method achieves significant improvements over the benchmark bio-inspired framework, HMAX, and other related methods on the Caltech dataset, under varying numbers of training samples and feature elements.

• International Journal of Automotive Technology
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• v.7 no.7
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• pp.859-866
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• 2006

This study employed the perturbation method, the Edgeworth series, the reliability optimization, the reliability sensitivity technique and the robust design to present a practical and effective approach for the robust reliability design of vehicle components with arbitrary distribution parameters on the condition of known first four moments of original random variables. The theoretical formulae of the robust reliability design for vehicle components with arbitrary distribution parameters are obtained. The reliability sensitivity is added to the reliability optimization design model and the robust reliability design is described as a multi-objection optimization. On the condition of known first four moments of original random variables, the respective program can be used to obtain the robust reliability design parameters of vehicle components with arbitrary distribution parameters accurately and quickly.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.10
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• pp.41-48
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• 2000

Manufacturing devices must be integrated for constructing CIM environment, but integration of heterogeneous system meets several economical and technological difficulties. In this case, MMS(Manufacturing Message Specification) can be an effective method, but it has problems which MMS products are generally very expensive and majority of the existing manufacturing devices do not support MMS. This paper describes the development of a gateway for Non-MMS-Compatible CNC machine tools to serve MMS and the implementation of OSI(Open System Interconnection) upper layer on TCP/IP. The developed system is applied to construct cell controller with heterogeneous devices under CIM environment and to evaluate interoperability and portability.

• Korean Journal of Remote Sensing
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• v.27 no.6
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• pp.743-752
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• 2011

One of main concerns of operators of the Earth observation satellite is taking images as many as possible under the constraints of satellite resources during fixed period. In order to achieve this goal, satellite operators are strongly required to generate the optimized image collection plans, and it is a very time consuming process to achieve an optimized image collection plan when it is done by manual. This paper suggests automation of image collection planning based on the dynamic programming algorithm to reduce the time required for image collection planning. The validity of the proposed method is tested using operating satellite system and the result is given in this paper.

• Proceedings of the KWS Conference
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• 1999.10a
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• pp.43-46
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• 1999

It has been suggested that the motivation for automation of welding processes ncludes the replacement and extension of the functions of human operators. Among these types of the welding automation, SAW(Submerged Arc Welding) was prevalently used, because it is highly suited to a wide range of application, especially for the high speed welding. A Significant portion of the total manufacturing time for a pipe fabrication process is spent on the welding following primary machining and fit-up processes. To achieve the reliable weld bead appearance, the automatic seam tracking and adaptive control to fill the groove are urgently needed. This paper proposed the mechanical functions of multi-torches welding system, flux supply and recovery system in conjunction with the complex air pulsing method and various types of methodologies. It was shown that the multi-torches welding system revealed the high welding qualities for the circular and rectangular pipes. In conclusion, the multi-torches welding system developed will contribute the advanced welding technology, welding automation and increment of the market in these areas.