• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.27 no.4
• /
• pp.297-303
• /
• 2014

Using the bond-based peridynamics and the parallel computation with binary decomposition, an adjoint shape design sensitivity analysis(DSA) method is developed for the dynamic crack propagation problems. The peridynamics includes the successive branching of cracks and employs the explicit scheme of time integration. The adjoint variable method is generally not suitable for path-dependent problems but employed since the path of response analysis is readily available. The accuracy of analytical design sensitivity is verified by comparing it with the finite difference one. The finite difference method is susceptible to the amount of design perturbations and could result in inaccurate design sensitivity for highly nonlinear peridynamics problems with respect to the design. It turns out that $C^1$-continuous volume fraction is necessary for the accurate evaluation of shape design sensitivity in peridynamic discretization.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2007.11a
• /
• pp.137-144
• /
• 2007

In the year of 1980 and 2000, the Korean government institutionalized the Value Engineering methodology in the construction phase and the design phase respectively. While design-phase VE have been applied to construction industry actively, which was institutionalized 7 years ago, construction-phase VE have not been applied to industry frequently, although it was institutionalized 25 years ago. On the other hand, at the time of social demands for VE is increasing, it has been pointed out that VE should be compatible with the delivery system. And the time of VE study, the operational management of VE study, and the maintenance process of the result of the VE study also should be considered. In this study, a scheme to improve VE methodology in the construction industry is proposed based on the literature review and the data analysis of domestic and foreign state of VE.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.35 no.1
• /
• pp.153-164
• /
• 2015

The methods of design of mat foundation may be classified as the rigid method and the flexible method according to the assumptions used. In the rigid method, the mat is assumed to be infinitely rigid and the contact pressure is assumed planar distribution. However, the contact pressure is not planar but curved surface because the real mat is not rigid. Therefore, it is not precise to analyze the mat foundation using the rigid method, and so there is no choice but to accept an error. On the other hand, in the flexible method, the mat is considered as the plate on the elastic foundation. This elastic plate theory is for the infinite plate acting a concentrated load on the elastic foundation. However, the functions for the moment, shear, and the deflection by the flexible method are very complex, there are many difficulties for the designer to use them. Also, it is impossible to use the design aid figures as a substitute of the complex functions, because they do not cover the values at the critical sections for the moment and shear. Therefore, in this research, the simplified functions for the moment, shear, and the deflection are proposed by regression analysis for an designer to use easily the flexible method. The simplified functions are very accurate and very ease to use.

• Applied Chemistry for Engineering
• /
• v.32 no.6
• /
• pp.621-626
• /
• 2021

A sequential design of experiments was used to optimize MOF-801 synthesis process. For the initial screening, a general 2^k factorial design was selected followed by the central composition design, one of the response surface methods. A 2³ factorial design based on the molar ratio of fumaric acid, dimethylformamide (DMF), and formic acid was performed to select the more suitable response variable for the design of experimental method among the crystallinity and BET specific surface area of MOF-801. After performing 8 synthesis experiments designed by MINITAB 19 software, the characteristic analysis was performed using XRD analysis and nitrogen adsorption method. The crystallinity with R² = 0.999 was found to be more suitable for the experimental method than that of BET specific surface area. Based on analysis of variance (ANOVA), it was confirmed that the molar ratio of fumaric acid and formic acid was a major factor in determining the crystallinity of MOF-801. Through the response optimization and contour plot of two factors, the optimal molar ratio of ZrOCl₂·8H₂O : fumaric acid : DMF : formic acid was 1 : 1 : 39 : 35. In order to optimize the synthesis process, the central composition design on synthesis time and temperature was performed under the identical molar ratio of precursors. The results derived through the designed 9 synthesis experiments were calculated using the quadratic model equation. Thus, the maximum crystallinity of MOF-801 predicted under the synthesis time and temperature of 7.8 h and 123 ℃, respectively.

• Proceedings of the Costume Culture Conference
• /
• 2005.04a
• /
• pp.157-159
• /
• 2005

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.8
• /
• pp.63-70
• /
• 2006

This paper presents design of the linear propulsion system of a high-speed (200km/h) dynamic tester for catenary-current collection. Among various propulsion systems, a permanent magnet linear synchronous motor is chosen for need of high acceleration force. The design is performed by the equivalent magnetic circuit method and verified by the finite element method. In addition, analysis of the main effects of various design variables for performance of the propulsion system has been done by using simulation-based DOE method.

• Proceedings of the KAIS Fall Conference
• /
• 2011.05b
• /
• pp.962-965
• /
• 2011

본 논문에서는 37kw이하 공용코어용 고효율 유도전동기 시제품 제작하였다. 시제품을 제작하기위해서는 전동기설계 및 해석이 필요하다. 방법으로는 전동기기본설계, 실험계획법, 등가회로법, 유한요소법 등이 있다. 이중에서 실험계획법에는 최적설계, 주요인자, 최적영역 등으로 나누어 분석할 수 있다. 설계 및 해석한 결과를 가지고 특성을 분석하고 재료비 및 효율을 비교하게 된다. 이를 바탕으로 5.5kw, 7.5kw, 11kw, 15kw 4극, 6극 공용코어용 고효율 유도전동기 시제품을 제작하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.04a
• /
• pp.41-45
• /
• 1996

비접촉방법데 의한 변위 측정기술은 공작물의 가공중(in-process)형상치수의 측정 또는 각종 계 측에 대한 자동화기술의 필요성이 증대됨에 따라 다양한 원리를 응용하여 발전되고 있다. 전통적인 방법으로는 가변 리럭턴스(variable reluctance)형, 와전류(eddy current)형, 콘덴서(capacitance)형 등의 전기적 센서들이 주를 이루고 있으나 최근에 들어서는 광전자기술의 발달에 힘입어 여러 광학 측정법들이 연구되어 실용화 되고 있다. 본 연구에서는 측정자동화 용도로 사용될 수있는 광삼각법에 의한 비접촉방식의 광학센서에 대한 기본 연구 결과를 서술하였다. 광삼각 비접촉 측정의 기본 원리와 측정 범위 및 분해능 관점에서의 센서 설계의 기본 방법을 제시하며 또한, 실제적인 센서의 설계 및 제작을 위해 응용될 수 있는 기본광학소자의 현 기술적 수준과 성능을 기술하였다. 최종적으로는 실제적인 센서의 설계제작 과정과 시제품의 성능 실험을 통한 응용 가능성이 검토되었다.

• Journal of the Korean Society for Precision Engineering
• /
• v.6 no.4
• /
• pp.126-135
• /
• 1989

In this study, in order to perform dynamic design of machine tools reasonably and effectively, a method was formulated to be applicable to the structures connected by joints having elasticity and damping by using substructure synthesis method. And to analyze chatter-free performance, a 3 dimensional cutting dynamics theory was used. Computer program package for the dynamic design of machine tools was developed by combining those and spplied to improvement of performance of NC lathe. Also, the optimization in the structural modifications of machine tool substructure was studied by evaluating the effects of the substructural modifications on total system performance.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.187-190
• /
• 2011

방파제 설계시 고려되는 파랑하중에 대한 설계 방법으로 기존 설계는 정수압만을 고려한 정적해석을 실시하였으며 최근 설계에서는 정정해석과 동적해석을 동시에 실시하고 있다. 하지만 이때의 동적해석 방법은 파랑하중에 의한 파압을 구조물내의 임의의 지점에서만 산정하여 등가파압으로 적용하여 해석을 하고 있다. 본 연구에서는 방파제의 경사면뿐만 아니라 해저지반에서의 파압을 추가적으로 고려함과 동시에 등 가파압이 아닌 모든 절점에서의 파압을 산정하여 파압을 적용하였다. 그 결과 현재의 설계법과 본연구의 설계법으로 구한 침하량의 값이 상당한 차이를 나타내고 있다.