• Proceedings of the Korean Information Science Society Conference
• /
• 2000.10a
• /
• pp.593-595
• /
• 2000

본 논문에서는 최적확장체(Optimal Extension Field; OEF)에서 정의되는 타원곡선 상에서 효율적인 스칼라 곱셈 알고리즘을 제안한다. 이 스칼라 곱셈 알고리즘은 프로비니어스 사상(Frobenius map)을 이용하여 스칼라 값을 Horner의 방법으로 Base-Ф 전개하고, 이 전개된 수식을 일괄처리 기법(batch-processing technique)을 사용하여 연산한다. 이 알고리즘을 적용할 경우, Kobayashi 등이 제안한 스칼라 곱셈 알고리즘보다 40% 정도의 성능향상을 보인다.

• Proceedings of the KIEE Conference
• /
• 1988.07a
• /
• pp.863-865
• /
• 1988

This paper presents a optimal Var allocation algorithm for minimizing transmission line losses and improving voltage profile in a given system. In this paper, nodal input data is considered as Gaussian distribution with their mean value and their variance. A Stocastic Linear programming technique based on chance constrained method is applied, to solve the var allocation problem with probabilistic constraint. The test result in 6-Bus Model system showes that the voltage distribution of load buses is improved and the power loss is more reduced than before var allocation.

• Proceedings of the IEEK Conference
• /
• 2000.07a
• /
• pp.363-366
• /
• 2000

This paper describes reconfiguration methods for processor arrays as a fault tolerance technique at the fabrication time. First, we show that any method based on a conventional idea cannot achieve optimal in reconfigurability. Then, we present two types of methods based on a new idea, that is sequential routing. The one is optimal in reconfigurability, and the other is advantageous in time complexity.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2008.05a
• /
• pp.225-229
• /
• 2008

We present an intelligent forging simulator AFDEX. The intelligent forging simulator is determined by the adaptive and optimal mesh generation technique and many intelligent application-oriented special functions which minimize the user-intervention during forging simulation. Of course, the solution accuracy should be optimized in the intelligent simulation. We have developed AFDEX to meet the requirement on intelligent simulation. Its characteristics are introduced with the help of typical application examples.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.18 no.1
• /
• pp.33-41
• /
• 2014

In a supersonic turbine, A rotor overlap technique reduced the chance of chocking in the rotor passage, and made the design pressure ratio satisfied. However, the technique also made additional losses, like a pumping loss, expansion loss, etc. Therefore, an approximate optimization technique was appled to find the optimal shape of overlap which maximizes the improvement of the turbine performance. The design variables were shape factors of a rotor overlap. An optimal design for rotor overlap reduces leakage mass flow rate at tip clearance by about 50% and increases about 4% of total-static efficiency compared with the base model. It was found that the most effective design variable is the tip overlap and that the hub overlap size is the lowest.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.12 no.3
• /
• pp.457-464
• /
• 1999

The object of this study is form finding, stress-strain analysis and cutting pattern analysis of membrane structures under the following assumptions : (1) material is linearly elastic (2) stress state is plane stress. The cable and membrane structures undergo large deformation because of its highly flexibility, therefore, we must take account of its geometric nonlinearity. The analysis procedure is consisted of three steps considering geometric nonlinearity unlike any other structures. First step is the form finding analysis to determine the initial equilibrium shape. Second step is the stress-strain analysis to investigate the behaviors of structures under various external loads. Once a stationary shape has been fount a cutting pattern based on the form finding analysis may be generated for manufacturing procedure. In this paper, form finding, stress-strain analysis and cutting pattern analysis is carried out for applying to Seoguipo worldcup soccer stadium roof structures and optimal cutting pattern analysis technique is proposed.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.14 no.2
• /
• pp.1-13
• /
• 2010

This paper proposes an optimal design method for the nonlinear seismic isolated bridge. The probabilities of failure at the pier and the seismic isolator are considered as objective functions for optimal design, and a multi-objective optimization technique is employed to efficiently explore a set of multiple solutions optimizing mutually-conflicting objective functions at the same time. In addition, a stochastic linearization method is incorporated into the multi-objective optimization framework in order to effectively estimate the stochastic responses of the bridge without performing numerous nonlinear time history analyses during the optimization process. As a numerical example to demonstrate the efficiency of the proposed method, the Nam-Han river bridge is taken into account, and the proposed method and the existing life-cycle-cost based design method are both applied for the purpose of comparing their seismic performances. The comparative results demonstrate that the proposed method not only shows better seismic performance but also is more economical than the existing cost-based design method. The proposed method is also proven to guarantee improved performance under variations in seismic intensity, in bandwidth and in the predominant frequency of the seismic event.

• Journal of Korea Water Resources Association
• /
• v.33 no.4
• /
• pp.447-459
• /
• 2000

Since the development of water resources is getting more difficult than ever before because of human-sociological condition, it would be necessary to develop a practically applicable technique for the management of water resources based on demand-side concept that could reduce unusable release for more effective and appropriate allocation of limited water resources. The objective of the study is to develop an optimal reservoir system operation model for water supply and energy augmentation by the combination of water budget analysis method in downstream area by MIP technique. The applicable study of the developed model was carried out and water supply capability of Nakdong river basin was re-evaluated by the developed model. The model has been found successful to guarantee appropriate water supply to the basin by means of deficit-supply management method and also turned out to be more practical tool for an optimal reservoir system operation model than other existing models.

• Journal of Biosystems Engineering
• /
• v.43 no.3
• /
• pp.219-228
• /
• 2018

Purpose: This study evaluated the feasibility of a near-infrared spectroscopy technique for the rancidity prediction of soybean oil. Methods: A near-infrared spectroscopy technique was used to evaluate the rancidity of soybean oils which were artificially deteriorated. A soybean oil sample was collected, and the acid values were measured using titrimetric analysis. In addition, the transmission spectra of the samples were obtained for whole test periods. The prediction model for the acid value was constructed by using a partial least-squares regression (PLSR) technique and the appropriate spectrum preprocessing methods. Furthermore, optimal wavelength selection methods such as variable importance in projection (VIP) and bootstrap of beta coefficients were applied to select the most appropriate variables from the preprocessed spectra. Results: There were significantly different increases in the acid values from the sixth days onwards during the 14-day test period. In addition, it was observed that the NIR spectra that exhibited intense absorption at 1,195 nm and 1,410 nm could indicate the degradation of soybean oil. The PLSR model developed using the Savitzky-Golay $2^{nd}$ order derivative method for preprocessing exhibited the highest performance in predicting the acid value of soybean oil samples. onclusions: The study helped establish the feasibility of predicting the rancidity of the soybean oil (using its acid value) by means of a NIR spectroscopy together with optimal variable selection methods successfully. The experimental results suggested that the wavelengths of 1,150 nm and 1,450 nm, which were highly correlated with the largest absorption by the second and first overtone of the C-H, O-H stretch vibrational transition, were caused by the deterioration of soybean oil.

• Journal of Korean Association for Spatial Structures
• /
• v.10 no.4
• /
• pp.113-122
• /
• 2010

Space frame structures are included in the large spatial structures and can adopt various structure types. But, it is not easy to choose the optimal member size and shape because it depends on the structural engineer's experience and the repeated trial and error. Therefore, in this study, the final goal is to help the designer with the selection of the optimum shape. First, various space frame structures with ellipse dome and vault complex types are chosen and the shape generation method is considered to generate the nodes, coordinates and members. In optimal design process of space frame structure, each node coordinate changes according to height variation or the number of rings. Therefore, the auto generation technique of nodes and members is required in order to consider this phenomenon in optimal design process. Next, the shape generation module is created, base on the shape generation method. This module is connected with the analysis module and the optimization algorithm. Finally, the example model is presented for the evaluation of the efficiency of optimization algorithms.