• Journal of the Korean Society for Precision Engineering
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• v.31 no.2
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• pp.119-123
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• 2014

Recently, laser processing technologies have been developed in many different industrial fields. The laser processing technologies are widely being applied such as laser assisted machining, cladding, heat treatment and coating. In the laser modules of the laser assisted machining system, laser lens is very important for accuracy and productivity of product. As the laser beam size, shape and focusing distance change, heat input energy of preheating point can be changed, the laser module of the laser assisted machining system should be equipped with various lenses differing beam size, beam shape and focusing distance. In this study, the rotary and linear laser modules are suggested. The finite element analysis is carried out to certify the static and dynamic stabilities of the developed laser modules. Finally, the rotary and linear laser modules have been fabricated successfully using the analysis results.

• Journal of KSNVE
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• v.8 no.3
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• pp.494-503
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• 1998

In this paper, in order to analyze dynamic characteristics of an automobile steering system consisting of many components, natural frequencies and transfer functions of each component and the total system are found on a FFT analyzer by experiments. Then, the data are transmitted to a commercial package program, CADA-PC. By analyzing the data, the mode shape of each natural frequency and damping values are obtained. Also, the function of a rubber coupling in column and telescoping effects on system are considered. C.A.E commercial programs are used to compare with the results of experiments. For the finite element modeling, I-DEAS is used. Data processing and post processing are operated on NASTRAN and XL, respectively. The ball-bearing and the linkage of shaft with column are modeled by spring element. Stiffness is modified from the results of experiments. The results of those show close agreement. In the mode shape of total system, wheel mode is dominant at lower frequency, while the column mode is main mode at higher. The role of rubber coupling in vibration isolation is clear on mode shape. Telescoping function makes natural frequency of column changed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.3
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• pp.329-336
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• 2000

An important problem associated with adaptive sidelobe canceller(SLC) systems is that their performance deteriorates with an increase in jammers arriving from different directions. Generally the number of jammers which can be effectively cancelled is limited by the number of the auxiliary elements in a SLC system. But the single-auxiliary-element with tapped delay line adaptive filter can effectively cancel multiple jammers. Therefore this paper proposed the spatio-temporal processing structure cascading adaptive array and tapped delay line adaptive filter and showed that this could obtain more rapid convergence rate and an increase of DOF without increasing the number of element.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.12
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• pp.1353-1361
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• 1992

Holographic optical element(HOE) is fabricated with the properties of lightweight, thin thickness and interconnectivity for free space. Particularly, HOE for optical interconnection and multiple image processing should have a high efficiency and equal spot intensity, Nonlinear equations for 2-dimensional binary phase grating(BPG) structure is solved by computer simulation based on modified Newton method. Computer-generated pattern drawn by plotter is scaled down and translated into the microfilm. After contact printing between the microfilm and silver halide hologram film, phase diffraction grating produces the $5{\times}5$ multiple spots. Experimental results are shown that bleached phase grating has a high efficiency and equal focused beams except central zero order.

• The Transactions of the Korea Information Processing Society
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• v.6 no.8
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• pp.2113-2123
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• 1999

The partial free order feature of Korean makes grammar size represented by CFG too big and that's why grammar has to contain all the ordered words. There are some problems to parse spoken language, because spontaneous spoken language has special features such as meaningless words, repetitious speech, etc. So, in this paper, we define 'Core-Concept' as the necessary element for parsing and we describe grammar only using Core-Concept. And we can prevent grammar from becoming very large and reduce an additional parsing burden as we select. Core-Concept described in grammar as parsing element. Through this strategy, we present that the simplified grammar can give us more efficient method to get right results. Experiments show that our parsing strategy has an average of 98% or over success rate in correct parsing results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8A
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• pp.821-828
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• 2008

In this paper, we present an optimized design of RS(23,17) decoder for UWB, which uses the pipeline structured-modified Euclidean(PS-ME) algorithm. Firstly, the modified processing element(PE) block is presented in order to get rid of degree comparison circuits, registers and MUX at the final PE stage. Also, a degree computationless decoding algorithm is proposed, so that the hardware complexity of the decoder can be reduced and high-speed decoder can be implemented. Additionally, we optimize Chien search algorithm, Forney algorithm, and FIFO size for UWB specification. Using Verilog HDL, the proposed decoder is implemented and synthesized with Samsung 65nm library. From synthesis results, it can operate at clock frequency of 250MHz, and gate count is 17,628.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.11a
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• pp.117-120
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• 2004

인터넷의 사용 증가로 정보의 양은 기하급수적으로 증가하고 있으며 웹 데이터의 표준인 XML의 데이터 표현의 유연성으로 인해 EDMS(Electronic Document Management Syste), ebXML(e-business extensible Markup Language)등 웹 기반의 전자문서를 이용하는 XML를 문서 교환 및 표준 문서 형식으로 도입하고 있는 실정이다. 이런 XML문서들을 저장관리 하기 위해 XML전용 Database도 현재 많이 연구되고 있다. 하지만 이런 XML전용 Database들은 관계형 데이터베이스보다 실용성이 떨어지는 점들이 많아 XML과 관계형 데이터베이스 매핑에 대한 연구도 활발히 진행중이다. 본 논문에서는 $C{\sharp}$을 이용하여 XML과 관계형 데이터베이스 간의 매핑을 위한 모듈을 개발하였으며, XML의 element와 관계형 데이터베이스의 필드를 상호 매핑시켜 줌으로 인해 XML문서의 element를 정확하게 저장, 관리 할 수 있다.

• The Transactions of the Korea Information Processing Society
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• v.6 no.5
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• pp.1153-1165
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• 1999

In various fields of information technology, it is growing up the needs about dynamic content management systems to store and manage SGML(Standard Generalized Markup language) documents in a database system. In this paper, we consider the issue of storing SGML documents that having complex hierarchical structure into a database system, and then propose a data model based on ODMG(Object Database Management Group) object model in order to store SGML documents without loss of information. Because the proposed data model reflects physical element structure and logical entity structure of SGML documents, it is able to store the SGML document in a database system at the system at the element- level granularity without any information loss. And also the proposed data model can be adapted among ODMG-compliant object database management systems. Finally, we will discuss on the implementation details of SGML repository system supports the functionality of automatic database schema creation for any DTD(Document Type Definition0, the functionality of storing the SGML document, the functionality of dynamic document assembly from stored database objects to SGML document, and the functionality of indexing and searching for database objects.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.366-373
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• 2007

In this paper we propose a multi-channel speech pickup system for calling quality enhancement of hands-free communication using ALTERA Nios-II processor. Multi-channel speech pickup system uses Delay-and-Sum beamformer with zero-padding interpolator. This paper implements speech pickup system using the Nios-II processor with real-time I/O data processing speed. The proposes speech pickup embedded system shows a good agreement with those of computer simulation(MATLAB) and conventional DSP processor(TMS320C6711) result. The proposed method is effective more than previous methods in cost and design processing time. As a result, LE(Logic Element) of hardware used 3,649/5,980(61%) on a chip.

• Korean Journal of Metals and Materials
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• v.47 no.6
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• pp.363-371
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• 2009

The effect of lubrication on the evolution of strain states during shape rolling in AA5052 sheet was studied by the finite element method (FEM) simulation. The strain states calculated by FEM were verified by texture analysis. Shape rolling with and without lubrication produces shape-rolled samples in fairly similar outer shapes, since the distribution of normal strain components is nearly independent of the lubrication condition. In contrast, the distribution of shear strain components strongly depends on the lubrication condition. Shape rolling without lubrication gives rise to the development of strong shear strain gradients leading to the formation of highly inhomogenous textures and microstructures. The {011}//ND fiber develops during rolling with the operation of plane strain plus ${\dot{\varepsilon}}_{22}$.