• The Transactions of the Korea Information Processing Society
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• v.6 no.8
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• pp.2204-2212
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• 1999

In this paper, we present techniques which perform incremental timing analysis using Timed Boolean Algebra that solves the false path problem and extracts the timing information in combinational circuits. Our algorithm sets histories of internal inputs that are substituted for internal output and extracts maximal delays through checking sensitizability of primary outputs. Once finding the sum of primitive delay terms, then it applies modified delay with referencing histories of primary output and it can extract maximal delays of primary outputs fast and efficiently. When the structure of circuit is changed, there is no need to compute the whole circuit again. We can process partial timing analysis of computing on the gates that are need to compute again. These incremental timing analysis methods are considered both delay changes and structure of circuit, and can reduce the costs of a trial error in the circuit design.

• International Journal of Highway Engineering
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• v.10 no.3
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• pp.129-138
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• 2008

The finite element method(FEM) was one of tools used to solve problem of previous Concrete Pavement and was applied to Korea Pavement Research Program Study. This study used the ABAQUS and the fortran analysis program to calculate the critical stress on jointed concrete pavement and compared and analyzed the results by using neural networks and linear regression model. In that case, which are not enough analysises by using FEM programs though many input variables, when the results of FEM with NN and linear regression models are compared, there are some differences. The other cases, which are reduced input variables and a lot of analysises each of them, results of Neural Networks(NN) and linear regression models are simulated to them of FEM. But, the result of NN is more exact than them of linear regression at the (0,0), (1,1). On the results of this study, it is suggested that the calculation of stress using NN is more compatible to Korea Pavement Research Program Study.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.4
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• pp.157-167
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• 2000

Korea Ocean Research and Development Institute performed the basic design of the Ear-Do Ocean Research Station in 1998. The design wave was taken to be the deep water wave which was obtained through wave hindcasting procedure. Wave forces acting on the structure were calculated by Morison formula utilizing the stream function theory of 5th. order. In the present study, a three dimensional hydraulic model testing was undertaken to investigate the validity of the basic design, measuring wave propagation over the Ear-Do, horizontal wave forces and air gaps. The measured forces were all compared by the corresponding values calculated by SACS program based on th design on the design wave. The results showed that in the three deep water wave directions (SSW, S, SE) the measured wave farces appeared less than the SACS calculated. But in the NNW wave direction, the measured forces generally exceeded the calculated values and showed a peculiar pattern very similar to the case that waves are superimposed by an unidirectional current. It was also found that the measured air gap underneath the structure appeared less than the values taken in the basic design for all wave directions.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.2
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• pp.106-112
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• 2007

This paper proposes a hybrid architecture algorithm for fast computation of DCT and DFT via recursive factorization. Recursive factorization of DCT-II and DFT transform matrix leads to a similar architectural structure so that common architectural base may be used by simply adding a switching device. Linking between two transforms was derived based on matrix recursion formula. Hybrid acrchitectural design for DCT and DFT matrix decomposition were derived using the generation matrix and the trigonometric identities and relations. Data flow diagram for high-speed architecture of Cooley-Tukey type was drawn to accommodate DCT/DFT hybrid architecture. From this data flow diagram computational complexity is comparable to that of the fast DCT algorithms for moderate size of N. Further investigation is needed for multi-mode operation use of FFT architecture in other orthogonal transform computation.

• Journal of the Korean Chemical Society
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• v.53 no.5
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• pp.499-504
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• 2009

Metals have often played important roles to some enzymatic reactions that are essential to biological processes. Therefore many scientists have studied the reaction mechanisms of catalytic reactions in metaloenzymes for many years. Methane MonoOxygenase (MMO) is an enzyme that oxidize methane to methyl alcohol. Recently Tolman et al. studied a model reaction for MMO, which is a hydroxide transfer reaction in Bis-($\mu$-oxo)-dicopper complex, and suggested several possible mechanisms. Later a two-step mechanism, which is hydrogen transfer followed by hydroxide rebound, was proposed from theoretical studies. In this study we calculated the reactant, product, and the transition state structures, and energetics of the first hydrogen transfer reaction using various DFT methods including recently developed the MO6 family of DFT, namely, MO6, MO6L, and MO6-2X. We found that the M06/6-31G(d,p)/LANL2DZ method reproduce the experimental XRD structure of reactants very well. The TS structures, barrier heights, and reaction energies depend very much on the size of the basis sets.

• Journal of the Korean Chemical Society
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• v.55 no.6
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• pp.905-911
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• 2011

The possible minimum structures of $C_{60}(CH_2)_nOH$ (n=0~2) and $C_{60}(OH)_2$have been optimized using density functional theory (DFT) with the 6-311G (d,f) basis set. The harmonic vibrational frequencies and IR intensities are also determined to confirm that all the optimized geometries are true minima. Also zero-point vibrational energies (ZPVE) have been considered to predict the binding energies. The predicted binding energy of $C_{60}CH_2OH$ is about 10 kcal/mol more stable than the binding energy of $C_{60}OH$.

• Journal of the Korean Magnetics Society
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• v.16 no.2
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• pp.115-120
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• 2006

Electronic and magnetic structure of $Cr_2Te_3$ have been studied, which is a material with complex magnetic structure. Density of states and magnetic moments show better agreement with experiments than LDA if they are obtained with the correlation effect of Cr-d electrons taken into account by the LDA+U method. In these calculations, the magnitude of the correlation effect is found to be 1.7 eV. It is shown that the magnitude of experimental magnetic moments of Cr atoms can be explained if the ferromagnetic states and the ferrimagnetic states have the same energy to be degenerate.

• The KIPS Transactions:PartA
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• v.14A no.3 s.107
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• pp.151-158
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• 2007

Quadtree, which is a hierarchical data structure, is a very important data structure to represent images. The linear quadtree representation as a way to store a quadtree is efficient to save space compared with other representations. Therefore, it has been widely studied to develop efficient algorithms to execute operations related with quadtrees. The computation of block location is one of important geometry operations in image processing, which extracts a component completely including a given block. In this paper, we present a constant time algorithm to compute the block location of images represented by quadtrees, using three-dimensional $n\times n\times n$ processors on RMESH(Reconfigurable MESH). This algorithm has constant-time complexity by using efficient basic operations to deal with the locational codes of quardtree on the hierarchical structure of $n\times n\times n$ RMESH.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1992.10a
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• pp.130-135
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• 1992

복잡한 구조물의 동특성 해석은 수치 해석적인 방법과 실험적 방법 모두 단 순 구조물의 동특성 해석에 비해 정확도가 떨어지는 반면 계산시간과 노력 은 크게 증가하게 된다. 이 경우 구조물 전체를 여러개의 간단한 부분 구조 계로 부할하고, 각 부분 구조계에 대해서 해석후 그 결과들을 적절한 결합 조건하에서 다시 조합하여 전체 구조계에 대해 동특성 해석을 수행하거나, 고감쇠 처리된 구조물과 같이 고전적 이론 해석기법의 적용이 어려운 경우 실험적인 해석방법과 이론적인 해서방법을 혼합 사용할 수 있는 부분 구조 합성법(Substructural Synthesis Method)을 사용하는 것이 효과적이다. 부분 구조합성법은 1) 응답특성을 이용한 방법 2) 모우드 특성을 이용한 방법 3) 특성행렬을 이용한 방법 등이 있으며 본 연구에서는 부분 구조계 응답함수 로부터 직접 특성행렬을 산출하는 방법을 이용하여 전체 구조계의 동특성을 해석할 수 있는 부분 구조 합성법을 제시하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.725-728
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• 2010

풍력실험결과를 이용한 풍하중 산정 방법은 고층건물에 작용하는 풍하중을 산정하는 대표적인 방법이다. 일반적인 고층건물의 경우, 이 방법은 구조물의 형상에 변화가 없다면, 구조물의 고유진동수가 증가할수록 구조물에 작용하는 풍하중 크기는 감소하는 특성을 가지고 있다. 한편, 재분배기법은 단위하중법을 통해 계산되는 변위기여도를 근거로 하여 구조물의 형상은 유지하면서 각 부재 단면의 크기만을 변화시켜서 구조물의 강성을 조절하는 설계기법이다. 이 방법은 효과적인 물량 재분배를 통해 구조물의 강성을 증가시키고 이를 통해 구조물의 고유진동수를 증가시키는 특징을 가진다. 본 논문에서는 재분배기법을 이용하여 고층건물 구조설계 시 구조물에 작용하는 풍하중 크기를 합리적으로 감소시키는 방법을 제안하였다. 제안된 방법을 풍력실험을 실시한 실구조물에 적용한 결과 구조물에 작용하는 풍하중 크기가 감소하고, 이를 통해 구조물량을 효과적으로 감소시킬 수 있음을 확인하였다.