• Communications for Statistical Applications and Methods
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• v.4 no.1
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• pp.75-90
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• 1997

본 연구는 범주형자료의 오분류에 관한 연구로, 2$\times$2분할표의 자료에 오분류가 있다고 생각되는 조사와 반복조사를 통해 정확하게 분류한 새로운 범주형자료를 시간이라는 새변수의 결합을 통해 오분류 여부를 탐색하는 방법에 대한 연구이다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.5
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• pp.899-909
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• 1992

An iterative solution technique is presented to analyze the dynamic systems of rigid bodies subjected to kinematic constraints. Lagrange multipliers associated with the constraints are iteratively computed by monotonically reducing an appropriately defined constraint error vector, and the resulting equation of motion is solved by a well-established ODE technique. Constraints on the velocity and acceleration as well as the position are made to be satisfied at joints at each time step. Time integration is efficiently performed because decomposition or orthonormalization of the large matrix is not required at all. An acceleration technique is suggested for the faster convergence of the iterative scheme.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.339-344
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• 2000

Newton-Raphson 기법은 구조물의 비선형 해석에 널리 쓰이는 반복계산기법이다. 비선형 해석을 위한 반복계산기법은 컴퓨터의 발달을 감안해도 상당한 계산시간이 소요된다. 본 논문에서는 신경회로망 예측을 사용한 Predicted Newton-Raphson 반복계산기법을 제안하였다. 통상적인 Newton-Raphson 기법은 이전스텝에서 수렴된 점으로부터 현재 스텝의 반복계산을 시작하는 반면 제시된 방법은 현재 스텝 수렴해에 대한 예측점에서 반복계산을 시작한다. 수렴해에 대한 예측은 신경회로망을 사용하여 이전 스텝 수렴해의 과거경향을 파악한 후 구한다. 반복계산 시작점이 수렴점에 보다 근접하여 위치하므로 수렴속도가 빨라지게 되고 허용되는 하중스텝의 크기가 커지게 된다. 또한 반복계산의 시작점으로부터 이루어지는 계산과정은 통상적인 Newton-Raphson 기법과 동일하므로 기존의 Newton-Raphson 기법과 정확히 일치하는 수렴해를 구할 수 있다. 구조물의 정적 비선형 거동에 대한 수치해석을 통하여 modified Newton-Raphson 기법과 제시된 Predicted Newton=Raphson 기법의 정확성과 효율성을 비교하였다. 제시된 Predicted Newton-Raphson 기법은 modified Newton-Raphson 기법과 동일한 해를 산출하면서도 계산상의 효율성이 매우 큼을 확인할 수 있었다.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.44-45
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• 2000

GHz 급의 아주 높은 반복율을 가지면서, 피코초 단위의 펄스 열을 발진시키는 레이저를 만들기 위해 능동형 모드록킹 방법을 이용하였다. 이 방법은 공진기안에 광 변조기를 삽입하고, RF 신호를 가하여 시간적으로 공진기내에서의 손실을 변화시키는 방법이다.$^{(1)}$ 공진기 길이를 충분히 길게 하면서도 고 반복율을 가지는 레이저를 만들기 위해 조화 모드록킹 방법을 사용했는데, 이는 레이저 펄스의 반복율을 공진기 길이에 의한 기본 반복율의 정수배가 되도록 하는 방법이다.$^{(2),(3)}$ 3차 조화 모드록킹 방법을 이용한 Nd:YLF 레이저 시스템을 그림 1에서 나타내었다. (중략)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.5
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• pp.422-428
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• 1988

An iterative learning control system is a control system which makes system outputs follow desired outputs by iterating its trials over a finite time interval. In a discrete time system, we proposed one method in which present control inputs can be obtained by a linear combination of the input sequence and time-shifted error sequence at previous trial. In contrast with a continous time learning control system which needs differential opreration of an error signal, the time shift operation of the error sequence is simpler in a computer control system and its effectiveness is shown by a simulation.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.343-347
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• 1997

Effect of culture conditions on the fermentation of wheat flour solution by mixed lactic acid bacteria of Lactobacillus brevis, L. fermentum and L. plantarum was investigated. The optimum temperature for the fermentation of wheat flour solution was $35^{\circ}C$ because pH decreased the lowest value and TTA (total titrable acidity) increased the highest value at this temperature. In aerobic condition, fermentor was purged with air at 1.0 vvm and was purged with nitrogen gas at 1.0 vvm in anaerobic condition. The decrease of pH and the increase of TTA in aerobic condition were higher than those in anaerobic condition. In aerobic condition, the optimum condition of oxygen supply was found to be oxygen transfer rate coefficient of $60\;hr^{-1}$ which corresponded to agitation speed of 250 rpm in a 5 L fermentor. Repeated fed-batch cultures were performed using pH-stat in order to increase the productivity of fermented wheat flour. With increasing the repeated fraction of culture volume, mean cycle time increased but maximum operation time decreased. However, the volume of produced broth per culture volume per time and total volume of produced broth per culture volume were maximum at the repeated fraction of culture volume of 20%. In a repeated fed-batch fermentation of wheat flour solution using mixed lactic acid bacteria, the culture condition was optimum at temerature of $35^{\circ}C$, aeration rate of 1.0 vvm, oxygen transfer rate coefficient of $60\;hr^{-1}$, and repeated fraction of culture volume of 20%.

• KSBB Journal
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• v.25 no.2
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• pp.179-186
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• 2010

We investigated the optimal strategy for ethanol production using flocculent Sacchromyces cerevisiae ATCC 96581. Considering the characteristic of flocculent yeast, a repeated fed-batch ethanol fermentation was designed, in which non-sterile glucose powder was fed every 12 hours and, after cell flocculation, new feeding medium was exchanged every 24 or 36 hours. We particularly compared this fermentation process with those when cell flocculation was not carried out. Finally, the maximal total ethanol production was 825 g-ethanol during 120 hours, in which the time interval of withdrawal-fill of feeding medium was 24 hours and cell flocculation was carried out.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.4
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• pp.11-19
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• 2001

In this paper, we study the convergence property of iterative learning control (ILC). First, we present a new method to prove the convergence of ILC using sup-norm. Then, we propose a new type of ILC algorithm adopting intervalized learning scheme and show that the monotone convergence of the output error can be obtained for a given time interval when the proposed ILC algorithm is applied to a class of linear dynamic systems. We also show that the divided time interval is affected from the learning gain and that convergence speed of the proposed learning scheme can be increased by choosing the appropriate learning gain. To show the effectiveness of the proposed algorithm, two numerical examples are given.

• The KIPS Transactions:PartA
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• v.16A no.5
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• pp.319-326
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• 2009

Since string operations were applied to computational biology area, various data structures and algorithms for computing efficient string operations have been studied. The longest common substring problem is an operation to find the longest matching substring in more than two strings, and maximal repeat of string problem is an operation to find substrings repeated more than once in the given string. These operations are importantly used in the string processing area such as pattern matching and likelihood measurement. In this paper, we present algorithms to compute the longest common substring of two strings and to find the maximal repeat of string using three-dimensional $n{\times}n{\times}n$ processors on RMESH(Reconfigurable MESH). Our algorithms have O(1) time complexity.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.9
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• pp.461-468
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• 2001

Though shared virtual memory (SVM) system promise low cost solutions for high performance computing they suffer from long memory latencies. These latencies are usually caused by repetitive invalidations on shared data. Since shared data are accessed through synchronization and the patterns by which threads synchronizes are repetitive, a prefetching scheme bases on such repetitiveness would reduce memory latencies. Based on this observation, we propose a prefetching technique which predicts future access behavior by analyzing access history per synchronization variable. Our technique was evaluated on an 8-node SVM system using the SPLASH-2 benchmark. The results show the our technique could achieve 34%~45% reduction in memory access latencies.