• International Journal of Aeronautical and Space Sciences
• /
• 제18권4호
• /
• pp.662-674
• /
• 2017

This paper describes the multidisciplinary design optimization (MDO) process of a tailless unmanned combat aerial vehicle (UCAV) using global variable fidelity aerodynamic analysis. The developed tailless UAV design framework combines multiple disciplines that are based on low-fidelity and empirical analysis methods. An automated high-fidelity aerodynamic analysis is efficiently integrated into the MDO framework. Global variable fidelity modeling algorithm manages the use of the high-fidelity analysis to enhance the overall accuracy of the MDO by providing the initial sampling of the design space with iterative refinement of the approximation model in the neighborhood of the optimum solution. A design formulation was established considering a specific aerodynamic, stability and control design features of a tailless aircraft configuration with a UCAV specific mission profile. Design optimization problems with low-fidelity and variable fidelity analyses were successfully solved. The objective function improvement is 14.5% and 15.9% with low and variable fidelity optimization respectively. Results also indicate that low-fidelity analysis overestimates the value of lift-to-drag ratio by 3-5%, while the variable fidelity results are equal to the high-fidelity analysis results by algorithm definition.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
• /
• pp.1504-1508
• /
• 1996

In this paper, we derive dynamic equation of helicopter and design controller based on variable structure system. It is difficult to control helicopter because it has non-linear coupling between input and output of system and is MIMO system. The design of control law is considered here using variable structure methodology giving the robustness to parameter variations and invariance to some subsets of external disturbance. However we derive dynamic equations of helicopter and design stabilizing variable structure controller. Also, simulation results are given in this paper.

• 한국과학교육학회지
• /
• 제25권2호
• /
• pp.111-121
• /
• 2005

이 연구에서는 초등학교 6학년을 대상으로 변인통제 능력이 요구되는 문제해결 과정에서 실험설계와 증거제시의 특성 및 어려움을 분석하였다. 연구 결과 변인통제 문제 해결 과정에서의 실험설계 유형은 원인 변인과 통제 변인의 통제나 변화 여부에 따라 통제변인변화형, 원인변인통제형, 완전변인통제형, 불완전변인통제형, 모든변인변화형으로 구분되었으며, 실험설계 과정에서 선행신념에 포함된 원인 변인값을 포함시키려는 경향이 강하게 나타났다. 결론에 대한 증거제시 사례를 분석한 결과 원인변인의 변화 여부, 통제변인 통제 여부, 실험결과와 결론의 일치 여부에 따라 완전변인통제형, 원인변인통제형, 원인변인변화형으로 구분되었으며, 원인변인통제형이 가장 빈도가 높았다. 실험설계에 비해서 증거제시에서의 변인통제 정도는 훨씬 낮았는데, 이는 선행신념에 포함된 원인 변인값에 집착한 증거제시, 증거 실험에서의 실험 결과와 선행 신념의 불일치, 다중변인과제에 대한 잘못된 선입견 때문인 것으로 나타났다. 따라서, 선행신념을 극복할 수 있고, 탐구 과정 요소의 특성이 반영된 다양한 변인통제 발달 프로그램이 개발되어야 할 것이다.

• 한국의류산업학회지
• /
• 제15권5호
• /
• pp.694-703
• /
• 2013

A variable dress design can be an alternative to satisfy a consumer need for diverse expression and self-realization at a lower cost factor. In the area of wedding dress, the change in the trend of wedding culture (which tends to demand more units of wedding dress) makes the cost factor more important in the purchase selection. A variable design has a clear advantage for wedding dresses and the wedding industry. This is the first research on a variable design that focuses on wedding dresses. This research develops a variable wedding design which respects consumer preferences independent of a variable wedding dress design that presents a new shape of silhouette or the development ofa new wedding dress materials. A survey on the supply side was conducted to examine market preferences by first browsing the Naver portal site and then checking the websites of major wedding dress suppliers. A questionnaire survey was conducted with a sample of 348 brides-to-be that inquired on wedding dress selection factors and purchase patterns. The survey shows that consumers prefer mermaid and A-line silhouettes, silk material, white-ivory color, and tube top necklines. The result conforms to the types commonly found in the designs of suppliers. We apply a detachable design to a basic mermaid silhouette and implemented change for 7 kinds of styles -based on the result of the survey. We suggest a variable wedding dress design as a new means to solve the cost concern and the customer need for diverse expression. The research represents a new life style for wedding culture and facilitates the development of the wedding industry.

• 전기의세계
• /
• 제23권2호
• /
• pp.46-54
• /
• 1974

The purposes of this paper are to deal with the design of m-input, m-output linear systems by the state variable feedback, and to extend the design capability of the state variable feedback design. The design requirements are decoupling and the exact realigation of desired transfer functions. Some methods are proposed to insert series compensators in the fixed plant in the cases when series compensators are needed to meet the input-output transfer matrix specification. The method for adding series compensators to the input channels of the fixed plant is shown by examples to lead both to the loss of the ability to decouple the augmented plant by the state variable feedback, and to the loss of desired zeroes. A method which avoids these two hazards is developed in which series compensators are put on the output channels of the fixed plant: it is proved that the augmented plant is F-invariant. By treating each subsystem individually, the designer can apply some of the previous developed knowledge of the state variable design of single-input, single-output systems.

• 대한기계학회논문집A
• /
• 제38권6호
• /
• pp.649-653
• /
• 2014

대부분의 신뢰성 기반 최적설계는 최적설계 과정에서 설계점이 이동함에도 불구하고 설계변수의 불확실성은 변하지 않는다. 하지만 실제 문제에서 설계변수의 값에 따라 불확실성이 변하는 경우가 있다. 예를 들어 철판의 두께가 설계변수이고, 철판의 제작공차가 불확실성인 경우, 철판의 두께에 따라 철판의 제작공차가 달라지기 때문에 설계변수의 값에 따라 그 값의 불확실성이 변한다. 본 연구에서는 설계변수의 값에 따라 불확실성이 변하는 것을 변동 불확실성으로 정의하고, 이를 신뢰성 기반 최적설계에 적용하는 변동 불확실성을 고려한 신뢰성 기반 최적설계 기법을 제안한다. 수학예제에서 변동 불확실성을 고려하지 않은 신뢰성 기반 최적설계와 변동 불확실성을 고려한 신뢰성 기반 최적설계의 비교를 통해 제안한 방법의 필요성을 확인한다. 또한 엔진 크래들의 변동 불확실성을 고려한 신뢰성 기반 최적설계를 통해 제안한 방법의 유용성을 확인한다.

• Journal of Biosystems Engineering
• /
• 제22권2호
• /
• pp.105-116
• /
• 1997

Using the design variables and conditions reported in the rut part of this paper, an analysis and optimum design of the tractor-rotary power driveline were carried out. The optimum design method involved 1 variable, 2 variable and multiple variable analysis performed as requested in the design process. In order to evaluate the effects of the design variables on the power transmission performance a sensitivity analysis were also conducted. the results indicated that the length and link point of the upper link, the upper hitch point of the implement master and the location of the implement input connection affect most significantly the driveline performance. The optimum design improved the performance of an exampled tractor-rotary driveline by 93% in terms of cosine ratio.

• 대한산업공학회지
• /
• 제39권5호
• /
• pp.422-428
• /
• 2013

In many cases, an $\bar{X}$ control chart which is based on the performance variable is used in industrial fields. However, if the performance variable is too costly or impossible to measure and a less expensive surrogate variable is available, the process may be more efficiently controlled using surrogate variables. In this paper, we propose a model for the economic design of a VSI (Variable Sampling Interval) $\bar{X}$ control chart using a surrogate variable that is linearly correlated with the performance variable. The total average profit model is constructed, which involves the profit per cycle time, the cost of sampling and testing, the cost of detecting and eliminating an assignable cause, and the cost associated with production during out-of-control state. The VSI $\bar{X}$ control charts using surrogate variables are expected to be superior to the Shewhart FSI (Fixed Sampling Interval) $\bar{X}$ control charts using surrogate variables with respect to the expected profit per unit cycle time from economic viewpoint.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1992년도 하계학술대회 논문집 B
• /
• pp.567-569
• /
• 1992

Design sensitivity analysis is proposed for the optimal shape design of three dimensional magnetostatic problems. The direct differentiation method is introduced for design sensitivity analysis and the boundary element method with reduced magnetic scalar potential as the state variable is used to analyze the magnetic characteristics. In the direct differentiation method, the design sensitivity, defined as the total derivative of the objective function with respect to the design variables, is calculated based on the variation of the state variable with respect to the design variable. And the variation of He state variable is calculated by differentiating the both sides of the system matrix equation obtained by applying boundary element method. Through the numerical example with simple electromagnet, the usefullness is proved.

• 대한전기학회논문지
• /
• 제41권8호
• /
• pp.850-857
• /
• 1992

Design sensitivity analysis is proposed for the optimal shape design of three-dimensional magnetostatic problems. The direct differentiation method is introduced for design sensitivity analysis and the boundary element method with reduced magnetic scalar potential as the state variable is used to analyze the magnetic characteristics. In the direct differentiation method, the design sensitivity, defined as the total derivative of the objective function with respect to the design variables, is calculated based on the variation of the state variable with respect to the design variable. And the variation of the state variable is calculated by differetiating the both sides of the system matrix equation obtained by applying boundary element method. Through the numerical example with simple electromagnet, the usefulness is proved.