• 한국정밀공학회지
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• 제18권2호
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• pp.177-185
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• 2001

This study shows the process design and forming analysis of permalloy shielding can that support the automobile multi-display parts to indicate the accurate information of car. This study is particularly important, since the strain and thickness of permalloy shielding can is known to affect the magnetic properties such as coercivity and permeability quite thickness of permalloy shielding can is known to affect the magnetic properties such as coercivity and permeability quite sensitively. The objective functions are strain and thickness deviation. The punch radius, die radius and blank holding force are considered as design parameters. Orthogonal array (OA) table and characteristics are applied to neural network (NN) as train data. After training, the optimal and robust condition of design parameters is selected. This study shows the correlation between the design methodology of NN and the statistical design of experiments (DOE) approach.

• 전기화학회지
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• 제17권3호
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• pp.193-200
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• 2014

고분자 분리막 연료전지의 성능향상을 위해 분리판 유로설계연구는 필요하다. PEMFC의 성능향상에 대한, 강제대류를 이용한 interdigitated 유로가 최근에 많이 연구되고 있다. 이 논문에서는 interdigitated 유로를 배플들이 있는 평행류 채널에 비슷하게 적용하였다. 상용 multiphysics program인 COMSOL을 이용하여 완전차단배플인 FBB가 있는 평행류 채널에 관해 전산해석을 수행하였고 3가지 변인들(배플 위치, 유체 방향, 유체 속도)이 사용 되었다. 각각 변인들의 출력은 최대출력의 80%를 고려한 0.5V에서의 결과이다. 최종적으로, 실험설계법 중 완전요인실험법을 바탕으로 여러 수준을 갖는 각 실험인자로부터 결론을 도출하였다. 실험인자들의 주효과와 상호작용 분석은 출력을 향상시키는데 가장 영향을 주는 인자를 찾는데 유용하였다.

• 대한기계학회논문집A
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• 제30권2호
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• pp.202-209
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• 2006

As the economic power is improved and the customer's demand is hard to please, the noise and vibration is the most important yardstick that can determine the quality of the product. Especially, as the airconditioner's demand increase suddenly, the product of quality and the noise is becoming a decisive factor of determining whether purchase the product or not. Therefore, every manufactory is investing a lot of money and research to cut down the unpleasantness induced from noise and vibration. And they are emphasizing their product's difference by advertising a silence very actively. With these reason, the demand of a silent indoor air-conditioner is the essential research filed when the product is develop(:d. In this study, the noise and vibration is visualized in the space and frequency domain by using experimental methods such as operational deflection shape (ODS), modal testing and sound intensity. Also the location of noise source and its characteristic is analyzed in an acoustical point of view to reduce the structure borne noise that come from the fan motor, and the pertinent control method is suggested. Furthermore, the most suitable shape of the motor bracket is suggested by applying FEM and DOE (Design of experiments) in the noise and vibration point a view.

• 대한기계학회논문집B
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• 제38권6호
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• pp.547-556
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• 2014

본 논문에서는 15,000 마력급 원심식 압축기 임펠러 블레이드에 대한 단방향 유체-구조 연성해석 및 응답표면법을 이용한 형상최적설계를 제시하였다. 임펠러 블레이드의 형상은 공력 성능에 영향을 미칠 뿐만 아니라, 유체의 압력과 원심력에 의한 임펠러의 구조적 안전성에도 큰 영향을 미치므로 유체-구조 연성해석을 함께 고려한 형상최적설계가 필요한 분야이다. 본 논문에서 유체-구조 연성해석의 유체영역과 구조영역을 ANSYS CFX와 Mechanical을 사용하여 각각 해석하였다. 실험계획법을 기반으로 유체 및 구조해석 결과에 대한 응답표면을 생성하여 구조적 안전성 및 압축비를 제한조건으로 하고 임펠러의 효율을 최대화하는 임펠러 블레이드의 형상최적설계를 수행하였다.

• 전기학회논문지
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• 제56권1호
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• pp.57-65
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• 2007

Along with the development of power electronics and magnetic materials, permanent magnet (PM) brushless direct current (BLDC) motors are now widely used in many fields of modern industry BLDC motors have many advantages such as high efficiency, large peak torque, easy control of speed, and reliable working characteristics. However, Compared with the other electric motors without a PM, BLDC motors with a PM have inherent cogging torque. It is often a principle source of vibration, noise and difficulty of control in BLDC motors. Cogging torque which is produced by the interaction of the rotor magnetic flux and angular variation in the stator magnetic reluctance can be reduced by sinusoidal air-gap flux density waveform due to reduction of variation of magnetic reluctance. Therefore, this paper will present a design method of magnetizing system for reduction of cogging torque and low manufacturing cost of BLDC motor with isotropic bonded neodynium-iron-boron (Nd-Fe-B) magnets in ring type by sinusoidal air-gap flux density distribution. An analytical technique of magnetization makes use of two-dimensional finite element method (2-D FEM) and Preisach model that expresses the hysteresis phenomenon of magnetic materials in order for accurate calculation. In addition, For optimum design of magnetizing fixture, Factorial design which is one of the design of experiments (DOE) is used.

• 한국생산제조학회지
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• 제18권4호
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• pp.410-416
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• 2009

In recent years, the rollover accident of large class of vehicles has become important safety issue. Even though the rollover form a small percentage of all traffic accidents, they have a fatal effect upon the driver and passenger. Among the traffic accidents occurred in driving, the rollover is the major cause of traffic fatalities. Therefore, it is required to develop the analytical and experimental techniques for predicting rollover propensity of vehicles and also to improve the vehicle suspension design in the viewpoint of rollover resistance. In this study, the parameter sensitivities for the roll angle of SUV suspension are analyzed, and then the determined design parameters are optimized by using the regression model function of the response surface methods. The analysis results show that the roll angle of the optimized vehicle is decreased as compared with the initial vehicle and also the rollover possibility is decreased when the roll rate of the front suspension is larger than the roll rate of the rear suspension.

• 한국정밀공학회지
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• 제32권9호
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• pp.815-824
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• 2015

In this study, we conducted the approximate multi-objective optimization of gap sizes of pressurized-water reactor (PWR) annular fuels. To determine the contacting tendency of the inner-outer gaps between the annular fuel pellets and cladding, thermoelastic-plastic-creep (TEPC)analysis of PWR annular fuels was performed, using in-house FE code. For the efficient heat transfer at certain levels of stress, we investigated the tensile, compressive hoop stress and temperature, and optimized the gap sizes using the non-dominant sorting genetic algorithm (NSGA-II). For this, response surface models of objective and constraint functions were generated, using central composite (CCD) and D-optimal design. The accuracy of approximate models was evaluated through $R^2$ value. The obtained optimal solutions by NSGA-II were verified through the TEPC analysis, and we compared the obtained optimum solutions and generated errors from the CCD and D-optimal design. We observed that optimum solutions differ, according to design of experiments (DOE) method.

• Wind and Structures
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• 제18권3호
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• pp.253-265
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• 2014

The platform and floating structure of spar type offshore wind turbine systems should be designed in order for the 6-DOF motions to be minimized, considering diverse loading environments such as the ocean wave, wind, and current conditions. The objective of this study is to optimally design the platform and substructure of a 3MW spar type wind turbine system with the maximum postural stability in 6-DOF motions as well as the minimum material cost. Therefore, design variables of the platform and substructure were first determined and then optimized by a hydrodynamic analysis. For the hydrodynamic analysis, the body weight of the system was considered, and the ocean wave conditions were quantified to the wave forces using the Morison's equation. Moreover, the minimal number of computation analysis models was generated by the Design of Experiments (DOE), and the design variables of the platform and substructure were finally optimized by using a genetic algorithm with a neural network approximation.

• 한국항공우주학회지
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• 제43권5호
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• pp.422-431
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• 2015

풍동실험에 적용하는 실험계획법을 연구하기 위한 선행 연구로써 KF-16의 정적 공력 데이터베이스를 구축하는 풍동 실험을 수행하였다. 본 실험에서 사용된 기체는 KF-16의 1/33 scale의 모델이며 수평 꼬리날개와 플래퍼론, 방향타를 모두 구현하였다. 크게 실험은 수평 꼬리날개의 유무에 따른 공력 특성 변화를 보기 위한 실험과 플랩, 플래퍼론, 방향타, 그리고 수평 꼬리날개의 변위각에 따른 공력특성 변화를 알아보기 위한 실험을 수행하였다. 실험 수행 후에는 각 실험들에 대해서 6가지 공력계수 그래프를 분석하고 반응 표면을 생성하면서 조종면의 변화가 각각 어떤 공력 특성에 큰 영향을 미치는지 알아보았다.

• 한국자동차공학회논문집
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• 제25권2호
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• pp.167-178
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• 2017

The steering wheel of a vehicle has a typical characteristic of automatically returning to its neutral state when the driver releases it. Steering returnability originated from the tire forces and kingpin moments. It is proportional to the reaction torque that is generated through the rack and column, which are dependent on suspension and steering geometry. It is also important to accurately predict and design it because steering returnability is related to steering performance. In this study, a detailed multibody dynamics model of a vehicle was designed by using ADAMS/Car and simulated for steering returnability. In addition, a tolerance analysis of the chassis system in terms of part dimension and properties has been performed in order to minimize the design parameters. The sensitivity of the selected design parameters was then analyzed via Design of Experiments(DOE). As a result, we were able to obtain the main parameters through a contribution analysis. It can be used to predict steering returnability and improve its performance, which is represented by the angle of restoration and laterality.