• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권4호
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• pp.219-225
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• 2000

This paper presents the shape optimization considering the uncertainty of design variable to find robust optimal solution that has insensitive performance to its change of design variable. Stochastic finite element method (SFEM) is used to treat input data as stochastic variables. It is method that the potential values are series form for the expectation and small variation. Using correlation function of their variables, the statistics of output obtained form the input data distributed. From this, design considering uncertainty of design variables.

• 대한기계학회논문집A
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• 제28권10호
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• pp.1574-1582
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• 2004

Binary manipulators have recently received much attention due to hyper-redundancy, light weight, good controllability and high reliability. The precise positioning of the manipulator end-effecter requires the use of many modules, which results in a high-dimensional workspace. When the workspace dimension is large, existing inverse kinematics methods such as the Ebert-Uphoff algorithm may require impractically large memory size in determining the binary positions of all actuators. To overcome this limitation, we propose a new inverse kinematics algorithm: the inverse kinematics problem is formulated as an optimization problem using real-valued design variables, The key procedure in this approach is to transform the integer-variable optimization problem to a real-variable optimization problem and to push the real-valued design variables as closely as possible to the permissible binary values. Since the actual optimization is performed in real-valued design variables, the design sensitivity becomes readily available, and the optimization method becomes extremely efficient. Because the proposed formulation is quite general, other design considerations such as operation power minimization can be easily considered.

• 소성∙가공
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• 제22권7호
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• pp.401-406
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• 2013

The use of roll-formed products increases every year due to its advantages, such as high production rates, reduced tooling cost and improved quality. However, till now, it is limited to part profiles with constant cross section. In recent years, the flexible roll forming process, which allows variable cross sections of profiles by adaptive roll stands, was developed. In this study, an attempt to optimize profile design for the flexible roll forming process was performed. An equation that predicts the longitudinal strain for part geometries with variable cross-sections was proposed. The relationship between geometrical parameters and the longitudinal strain was analyzed and investigations on the optimal profile design were performed. Experiments were conducted with a lab-scale roll forming machine to validate the proposed equation. The results show that the profile design method proposed in this study is feasible and parts with variable cross sections can be successfully fabricated with the flexible roll forming process.

• 전자공학회논문지A
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• 제29A권2호
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• pp.33-40
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• 1992

The design method of signal delay line system using indirect frequency synthesizer is presented. The variable signal delay line system with 2[nsec] step of delay time at center frequency 60[MHz], bandwidth 500[KHz] and range 5.24-5.81[x10S0-6Tsec] is designed and fabricated. The results were met with good characteristics to be variable delay time of average 2.01[nsec] per step.

• International Journal of Precision Engineering and Manufacturing
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• 제3권3호
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• pp.28-36
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• 2002

The continuously variable transmission (CVT) mechanism considered here is the output coupled type which combines the functions of a 2K-H I type differential gear unit and a V-belt type continuously variable unit (CVU). One shaft of the CVU is connected directly to the output shaft and another shaft of it is linked to the differential gear unit. It is shown that some fundamental relations (speed ratios, power flows and efficiencies) for twelve mechanisms previously described are valid by various experimental studies, six of them produce a power circulation and the others produce a power split. Parametric analysis is carried out in relation to the efficiency, speed ratio and power ratios in order to assist in the design of an optimum configuration. Some useful properties associated with power flow modes also are discussed in the output coupled type continuously variable transmission.

• 한국CDE학회논문집
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• 제6권3호
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• pp.206-214
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• 2001

This paper describes the wire EDM (Electric Discharge Machining) CAM system considering a variable taper wire-cut and an unmanned wire EDM during the night. Wire EDM is applicable to all materials that are fairly good electrical conductors, including metals, alloys and most carbide. Thus it provides a relatively simple method for making holes of any desired cross section in materials that are too hard or brittle to be machined by most other methods. In this paper we classify variable taper wire-cut machining patterns and variable taper wire-cut geometries. Also we determine unmanned wire EDM patterns fur the productivity of wire EDM industry. Developed system consists of two modules: 1) Variable taper wire EDM module guarantees the length ratio machining function, the parametric ratio machining function and the marking function. 2) Unmanned wire EDM module guarantees the automatic wire EDM during the night. The proposed system has been tested in the fields and found to be a useful system.

• 대한기계학회논문집A
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• 제35권10호
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• pp.1273-1279
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• 2011

자동차 압축기는 연비 개선효과를 위해 가변 사판형 압축기를 사용한다. 가변 사판의 회전 토크와 피스톤에 작용하는 압력은 사판의 형상과 변형에 중요한 영향을 미친다. 본 논문은 Chebyshev 직교다항식과 최적화 기법을 이용하여 가변 사판의 최적 형상을 결정하였다. 사판의 설계 요구사항은 정상 운전상태에서 최대 응력과 변형을 최소화하면서 체적을 감소시키는 것이다. 직교배열표, 분산분석과 반응표면최적화 방법은 최적 설계변수를 결정하고 주효과를 찾는데 사용하였다. 최적설계 결과로부터, 사판의 유의한 설계변수를 확인하고 이의 최적해와 설계요구조건 만족에 대한 유용성을 설명하였다.

• 동력기계공학회지
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• 제14권3호
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• pp.33-38
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• 2010

Technology of vehicle industry has been developing and it is required a better vehicle performance than before. Therefore, the consumers are asking not only an economic efficiency, functionality, polished design, ride comfort and silence but also a driving stability. The ride comfort, silence and driving stability are influenced by the size of vehicle and various facilities. But the principal factor is a room noise and vibration sensed by a driver and passenger. Thus, the NVH of vehicle has been raised and used as a principal factor for evaluation of vehicle performance. The primary objective of this study is an optimized design of powertrain mounting system. To optimized design was applied MSC.Nastran optimization modules. Results of dynamic analysis for powertrain mounting system was investigated. By theses results, design variables was applied 12 dynamic spring constant. And the weighting factor according to translational displacement and rotational displacement applied 3 cases. The objective function was applied to minimize displacement of powertrain. And the design variable constraint was imposed dynamic spring constant ratio. The constraint of design variable for objective function was imposed bounce displacement for powertrain.

• 한국의류학회지
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• 제17권3호
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• pp.475-490
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• 1993

Even though modem ideal body type is rather tall and slim one, most of women don't coincide with it exactly. The objective of this research was to study the optical illusion effect of clothing design line so that average Korean women can approach the modern ideal body type. This research also tried to show the more scientific method to make stimulus by computer simulation and to present quantitative data. For the experiment, 9 design variables were selected from design principal book as follows : waistline level, skirt length, horizontal line emphasis, vertical line emphasis. princess line, vertical stripe, horizontal stripe, diagonal stripe. Each variable was divided into 4 levels so that 36 experimental designs were made. Visual stimuli which same model was wearing each design were recreated by the CAD system. These were given to evaluating panels through slide projecter. Then panels compared experimental design with basic design by 'tall effect' and 'slim effect', All the data from the experiment were analyszed by ANOVA and DUNCAN test for multiple comparison to study significance, direction(positive or negative), degree, proper extent of optical illusion effect. The result showed that some designs have optical illusion effect to make better look. In addition, it proved that the stronger design variable does not mean the more optical illusion effect and there was proper extent which produce the best illusion effect in each design variable.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 춘계학술대회논문집
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• pp.141-145
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• 2000

A systematic method to find the optimal blank shape for sheet forming is proposed by coupling the numerical simulation technique. A weighted parameter was introduced in order to simplify the multi-variable optimization problem to a single-variable problem. The proposed method has been applied to the blank design of drawing processes to obtain the near-net shape within the required error bound after forming, Excellent results have been obtained between the numerical results and the target contour shapes. Through the investigation the proposed systematic method for optimal blank design is found to be effective in the practical forming processes