• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.4
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• pp.373-378
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• 2002

This paper presents the results of an electromagnetic field uniformity of a triangular reverberation chamber that can be used alternatively for analysis and measurement of electromagnetic interference and immunity test. Equilateral triangular reverberation chamber and Schroeder diffusers were designed and fabricated for this purpose. FDTD simulation method was applied to analyze the field distribution inside of two different types of reverberation chambers. As a result, the electromagnetic field uniformity was improved inside of triangular reverberation chambers, and the measured field uniformity was improved by 1 ∼4 ㏈ compared to the ones without diffusers.

• 전기의세계
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• v.53 no.5
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• pp.57-60
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• 2004

VTK란 Visualization ToolKit의 약자로서 그래픽 합성, 영상처리 및 3차원 데이터 가시화의 기능을 제공하는 소프트웨어 라이브러리이다. VTK는 1993년도에 William J. Schroeder, Ken Martin 및 Bill Lorensen이 공동 집필한 "The Visualization Toolkit： An Objectet-Oriented Approach to 3D Graphics" 책이 출판되면서 널리 알려지기 시작하였다. 이 책의 주저자이며 현재 Kitware 회사(http://www.kitware.com의 사장인 Schroeder는 이 책의 서문에서 데이터의 가시화 (visualization)이란 방대한 데이터를 단순한 숫자나 그림으로 표현하는 것 보다 시각적으로 표현하는 것이라고 정의를 하였으며, 또한 데이터의 시각화를 통하여 데이터의 특성을 이해하고 응용하기가 쉬우며 다양한 측면에서 데이터를 해석 또는 분석 이 가능하다고 주장하였다.(중략)

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.4 s.119
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• pp.372-378
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• 2007

This paper presents an improvement of field uniformity in a reverberation chamber with QRDs(Quadratic Residue Diffuser) and also shows the optimal dimension of the QRDs. The QRD is designed for $1{\sim}3\;GHz$ frequency band and the FDTD(finite-Difference Time-Domain) method is used to analyze the field characteristics. At 2 GHz, the standard deviation of test volume in the reverberation chamber is the smallest when the QRD has $30{\sim}60\;%$ coverage of one side of the reverberation chamber and the field uniformity is worsened when the coverage of the QRD is either below 20 % or above 70 % of the area of the side wall. Particularly, the standard deviation of test volume in the reverberation chamber with 30 % coverage of QRD is improved by 1.53 dB compared to that of the reference chamber with no QRDs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.4 s.95
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• pp.373-379
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• 2005

Papers on improvement of electromagnetic field uniformity in a reverberation chamber with 1D Quadratic Residue Diffuser of Schroeder method has been published several times. In this paper, to obtain improved electromagnetic field characteristics and field uniformity in a reverberation chamber, cubical residue diffuser sets of Schroeder type are designed for a chamber in $2.3\;\cal{GHz}\~3\;\cal{GHz}$. The FDTD(Finite-Difference Time-Domain) technique is used to analyze the field characteristics in a chamber. Cubical residue algorithm and 2D arrangement show more randomness than the previous study results. The characteristics of tolerance, polarity, deviations, as well as power efficency, are improved with cubical residue diffuser sets in a chamber.

• Applied Chemistry for Engineering
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• v.4 no.2
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• pp.409-415
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• 1993

A potential function is applied to a hydrogen bonded system such as O-H---O and is slightly modified to provide a good understanding of a range of data. The use of this model requires a knowledge of terms describing the Van der Waals repulsion and the electrostatic interaction and the determination of these terms form the equilibrium conditions is described. Using this simple model, it will be shown that the relationship between the frequency shift and enthalpy of hydrogen bond formation is predicted to be linear and this is in reasonable agreement with experimental results in the literature.

• The Journal of the Acoustical Society of Korea
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• v.25 no.6
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• pp.257-268
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• 2006

To determine the faults of ceramic cup it is proposed to use pseudo reverberation time concept estimated by impact test in room. Schroeder curves estimated from impact test for a cup with small crack and without one are utilized to estimate pseudo reverberation time. Pseudo reverberation times are compared and discussed according to a sort of impact hammers and impact points and also boundary conditions. As a result. proposed method is proved to be very useful to detect the existence of faults for candidate cups.

• Korean Journal of Social Welfare
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• v.57 no.2
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• pp.231-252
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• 2005

The changing Agenda of the family policy is to be influenced by many factors. The structural change of population and aging problem in modern society are generally included in main factors which produce political needs. Therefore, migrant family is recognized as a alternative which is to resolve the socioeconomic problems of aging industrial societies. In Germany, Gerhard Schroeder who leads the SPD governs since 1998. The Schroeder's new conception of welfare policy is known as the third way("neue Mitte") which the social economic structure intends to neo-liberalistic trend. The concern on the welfare policy for the migrant families has grown recently in neo-liberalistic age, but research on german welfare policy for migrant families is very limited in quantity and Depth. The main purpose of this study is to examine how the welfare policy for the migrant families of Schroeder-government has been developed in Germany. And this paper evaluates the results of transforming policy. Based on this evaluation, this paper attempts to be manifest the problem of korean family policy for the migrant population and to find out implications of german model.

• Korean Journal of Social Welfare
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• v.53
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• pp.155-178
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• 2003

Traditionally, the Sozialdemokratitische Partei Deutschlands(SPD) guards strictly radical welfare conception and intends to support the disabled with universal welfare-political instruments. After the oil-shock in 1973, European welfare states including Germany had experienced stark financial crisis because of economic unstability and increasing social expenditure. The political direction of SPD has been gradually changed. This transformation has been reflected automatically on the welfare policy for the disabled. In Germany, Gerhard Schroeder who leads the SPD governs since 1998. The Schroeder's new conception of welfare policy is known as the Third Way("neue Mitte") that the social economic structure intends to neo-liberalistic trend. The concern on the employment policy for the disabled has grown recently in neo-liberalistic age, but research on German employment policy for the disabled is very limited in quantity and depth. The main purpose of this study is to examine how the employment policy for the disabled of Schroeder-government has been developing in Germany. And this paper evaluates the effect of transforming policy. Based on this evaluation, this paper attempts to manifest the problem of Korean employment policy for the disabled and to find the implications of German model.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.11
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• pp.973-981
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• 2013

The main role of an acoustic diffuser is to diffuse reflected sound field spatially. Since the pioneering work of Schroeder, there have been investigations to improve its performance by using shape/sizing optimization methods. In this paper, a gradient-based topology optimization algorithm is newly presented to find the optimal distribution of reflecting materials for maximizing diffuser performance. Time-harmonic acoustic analysis in a two-dimensional acoustic domain is carried out where the domain is discretized by finite elements. Perfectly matched layers are placed to surround the domain to simulate non-reflecting boundary conditions. Design variables are assigned to each element of which material properties are interpolated between those of air and those of a rigid body. An approach to extract the reflected field from the total acoustic field is employed. To validate the effectiveness of the proposed method, design problems are solved at different frequencies. The performance of the optimized diffusers obtained by the proposed method is compared against that of the conventional Schroeder diffusers.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.229-232
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• 2002

콘서트 홀과 같은 대형 공간의 경우와는 달리, 자동차 내의 작은 공간에서는 저주파의 음향 공진으로 인하여 상대적으로 높은 크로스오버 주파수까지 재생된 사운드가 컬러링 된다. 이러한 크로스오버 주파수는 Schroeder의 'large room limit'로 결정되며, 이것은 작은 공간과 대형 공간을 구분하게 되는 기준이 된다. 이러한 컬러링을 보상하기 위해, 먼저 대역 제한된 사인 스윕 신호를 이용하여 특정 차량의 저주파 응답 범위를 크로스오버 주파수까지 측정하였다. 본 논문에서는 이렇게 측정한 저주파 응답을 이퀄라이징하는 방법에 대하여 논의한다.