• Communications of Mathematical Education
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• v.16
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• pp.149-162
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• 2003

수는 도대체 어디서 생겨났을까? 언제쯤부터 어떤 필요에 의해 인간이 사용하기 시작하였을까? 학생들이 이러한 호기심을 한 번쯤 가져본다면 얼마나 좋을까? 그러나 학생들은 십진기수법의 체계에 너무나 잘 길들어져 있기 때문에 그 고마움에 대해서 잘 모른다. 조류즈 이프라는 '신비로운 수의 역사'에서 인간 지성의 환상적 모험이 만들어낸 1, 2, 3, 4, 5, 6, 7, 8, 9, 0에 대하여 불의 사용이나 전기의 발명만큼이나 혁신적인 사건으로 취급하고 있으며 수의 역사는 인간의 보편적인 지성이 이루어 낸 영원히 무너지지 않는 바벨탑으로서, 인종차별까지 극복해낸 위대한 가능성임을 가슴 뿌듯하게 전해 준다. 따라서 본 연구에서는 이러한 인류 역사의 놀라운 소산인 수의 위대함을 깨닫기 위하여 세계 여러 문명들 속에서 숫자가 생겨난 연유, 그 표기 방법 및 그 이후부터의 발달 모습을 학생들이 탐구해 보게 하기 위하여 기수법과 수체계에 대한 지도 방법에 대하여 연구하고자 한다.

• Microbiology and Biotechnology Letters
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• v.30 no.1
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• pp.21-25
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• 2002

Structural analysis was performed by the $^1$H-NMR, $^{13}$ C-NMR, amino acid composition analysis and FAB-mass. The instrumental analysis represented that the potential antifungal antibiotic belonged to the iturin E group antibiotic, consisting of 7 $\alpha$-amino acid residues and a collection of $\beta$-amino acid with aliphatic side chain. Compared to the Iturin E group, notably, the potent antifungal antibiotic from Bacillus sp. YJ-63 carried longer $\beta$-amino acid side chain. In conclusion, these findings identified a potential antibiotic, which contained a stable cyclopeptide structure with long $\beta$-amino acid side chain.

• TTA Journal
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• s.55
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• pp.72-93
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• 1998

통신망의 신기술이 계속하여 등장하는 가운데 `표준`의 역할이 다시 클로즈업되고 있다. 정보통신제품의 특징이야말로 표준의 구현자체에 있기 때문이다. Vendor가 타사보도 먼저 최신 표준을 실제로 적용 완료하는 가장 효과적인 길은 자사의 독자기술을 표준화해 버리면 된다. 표준화를 둘러싼 치열한 경쟁으로 인하여 ''첨단기술을 싼값으로 널리 보급시키는'' 표준본래의 목적 조차도 외면 당하기 쉬운 경향이다. 표준화란 무엇인가? 표준의 가치는 어디서 찾을 수 있을까? 그 구체적인 사례와 증언을 토대로 아래와 같이 세 개의 부로 나누어 각 사항들을 점검해 본다. 제1부에서는 사실표준과 공식표준의 특징과 그 실태를 알아보고 제2부에서는 현재 계속 확산되어 가고있는 국제표준쟁탈전의 현장을 보고하고, 시장원리의 파도에 흔들리고 있는 표준화활동의 실태를 밝힌다. 제3부에서는 표준화활동의 제1선에서 활약하는 기술자의 증언 등을 토대로 ''표준''에 대한 환상과 진실을 알아본다.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.3
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• pp.237-246
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• 1989

A sliding memory covariance circular lattice (SMC-CL) filter and an efficient ARMA modeling method using the SMC-CL filter are presented. At first, SMC-CL filter is derived based on the geometric approach. Then ARMA process is converted into 2 channel AR process, and SMC-CL filter is applied to it. The structure of SMC-CL filter becomes simpler in case of ARMA modeling due to the whiteness of a driving input process. The parameters of ARMR process can be obtained by the Levinson recursions from the PARCOR coefficients of the second channel of the filter. Computer simulations are performed to show the effctiveness of the proposed algorithm.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.3
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• pp.61-66
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• 2002

Electric power distribution networks are prime examples of systems where a very high degree of reliability is expected. Reliability is the probability of a device or system performing its function adequately for the period of time intended and intented operating conditions intented. This paper shows that a better meshed distribution configuration over the case study of radial configuration distribution system was selected by comparing the indices obtained from EDSA\`s reliability worth assessment of distribution systems program.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.82-85
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• 1998

1. 서론 : Cyclodextrin(CD) 동족체(homologues)는 $\alpha$-, $\beta$-, $\gamma$-CD로 구분되며, 이들 각각은 $\alpha$-D-glucopyranose 단위체 6,7, 및 8개가 비환원성 환상구조로 연결된 cyclic maltooligosaccaride의 일종으로 외부는 친수성이고, 내부는 소수성인 공동 구조를 갖고 있다. 따라서 각 CD는 동공의 크기가 달라 다른 크기의 소수성 물질들과 선택적인 포접화합물 (inclusion compound)을 형성하는 특징이 있다. CD 동족체는 전분 분해 효소인 cyclodextrin glycosyltransferase(CGTase)에 의해 전분으로부터 생산되는데, 반응용액 내에서의 CD 동족체 농도가 어느 한계값 이상으로 높아지면 생산물 저해와 다른 환원당으로의 분해 때문에 생산성이 감소하여 이의 효과적 생산에 어려움이 있다. 본 연구는 dead-end 및 cross-flow형 막 생물반응기를 사용하여 CGTase에 의한 전분의 CD 동족체로의 분해반응시 생산물 저해를 억제시켜 생산성을 향상시키고, 동시에 조작조건 변화에 따른 생산물인 CD 동족체의 효과적인 연속분리 가능성을 검토하였다.

• Transactions of Materials Processing
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• v.12 no.7
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• pp.631-639
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• 2003

Ring rolling process is simulated by using the general-purpose commercial finite element analysis software, MSC.Superform. Because the deforming region is restricted to the vicinity of the roll gap, only a ring segment spanning the roll gap is analyzed in order to save computation time and cost. First, a plain ring rolling of rectangular cross-section is simulated. Comparisons between computation and experiment show good agreement in the cross-sectional configuration of the deformed ring. Then, a profile ring with an external round groove is analyzed. The rolls with and without groove have been analyzed to compare the amount of side spread. It is found that the grooves in the rolls are effective in reducing the amount of side spread.

• Transactions of Materials Processing
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• v.24 no.3
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• pp.161-166
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• 2015

The finite element method has been widely used in the analysis of ring rolling. For ring rolling it requires a high computational expense due to the non-steady state material flow characteristics of the process. The high computational expense causes the finite element analysis to be impractical for industrial applications. In the current study, we aim to develop a practical implicit finite element modeling method for ring rolling. This method uses a step-wise steady state assumption and is called the “Stepped method”. The stepped method divides the whole process time of unsteady-state flow model into a finite number of steady-state models. It then solves the process at several specific time steps until convergence is reached. In order to confirm the performance and validity of the newly proposed stepped method, the result from the stepped method were compared to the results from a Lagrangian finite element method and to results from experiments reported in the literature.

• Solar Energy
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• v.7 no.1
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• pp.53-60
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• 1987

Natural convection in the annulus between concentric inclined cylinders has been studied by the numerical analysis. Governing equations are numerically solved by means of successive over-relaxation methods for a range in orientation from horizontal to vertical. It is found that flow patterns can also be observed the co-axial double spiral. As the angle of inclination is increased, the center of the eddy is shifted into the lower part of annulus and flow structure is apparently changed. In the present study, the maximum local Nusselt numbers for the inner and outer walls at the vertical cylinder increase more than those at the horizontal cylinder by 71%, 42% respectively. Consequently the effect of inclination on the heat transfer is considerably large.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1379-1388
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• 2008

In this paper, we present the equations of motion by which the natural vibration of a rotating annular disk can be accurately analyzed. These equations are derived from the theory of finite deformation and the principle of virtual work. The radial displacements of annular disk which is rotating at constant angular velocity are determined by non-linear equations formulated using 1-dimensional finite elements in radial direction. The equations of the in-plane vibrations at disturbed state are also formulated using 1-dimensional finite elements in radial direction along the number of nodal diameters. They are expressed as in functions of the radial displacements at the steady state and the disturbed displacements about the steady state. In-plane static deformation modes of the annular disk are used as the interpolation functions of 1-dimensional finite elements in radial direction. The natural vibrations of an annular disk with different boundary conditions are analyzed by using the presented model and the 3-dimensional finite element model to verify accuracy of the presented equations of motion. Its results are compared and discussed.