• 전자공학회논문지A
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• 제30A권8호
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• pp.57-62
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• 1993

In this paper, both feasible power gain and power added efficiency at the operating center frequency of 12 GHz are stressed to design a power FET with double-heterjunction structure. The variable parameters or the design are the unit gate width, the gate length, the doping density of AlGaAs, the AlGaAs thickness, the spacer thickness, the Al mole fraction, and the GaAs well thickness. The results of simulation for the FET with 1.mu.m gate length show that the power gain and the power added efficiency are 10.2 dB and 36.3% at 12GHz, respectively. An extrapolation of the relation between current gain and unilateral gain yields a 17 GHz cutoff frequency and 43GHz maximum frequency of oscillation. The calculation of the current versus voltage characteristics show that the output power of the device is about 0.62W.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.410-415
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• 2000

In this paper feasible direction method which is one of the optimization method is adopted to natural frequency optimization. In order to find the optimum design of structures that have characteristic natural frequency range, a numerical optimization method to solving eigenvalue problems is a widely used approach. However most cases, it is difficult to decide the accurate thickness and shape of structures that have allowable natural frequency in design constraints. Parallel analysis algorithm involving the feasible direction optimization method and Rayleight-Ritz eigenvalue solving method is developed. The method is implemented by using finite element method. It calculated the optimal thickness and the thickness ratio of each element of 2-D plane element through the parallel algorithm method which satisfy the design constraint of natural frequency.

• 조명전기설비학회논문지
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• 제28권5호
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• pp.39-51
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• 2014

This paper deals with design of a direct-coupled, small-scaled permanent magnet generator (PMG) for wind power application. First, this paper determines rated power and speed of the PMG from measured characteristics of wind turbines. Second, we derive analytical solutions for the open-circuit field in order to determine optimum magnet thickness and pole pitch/arc ratio. Third, on the basis of open circuit field solutions, stator magnetic circuit including slot opening, teeth width and yoke thickness is designed. And then, a diameter of stator coil which agree with a required current density is calculated, and its turns are determined from the area of slot considering winding packing factor. Finally, finite element (FE) method is employed in analyzing the details of the designed PMG and, test results such as back-emf measurements are given to confirm the design.

• 정보저장시스템학회논문집
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• 제7권1호
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• pp.13-18
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• 2011

As a standard of optical disk drive (ODD) was determined to Blu-ray diks (BD), researches for securing slim drive thickness, high data transfer rate and high capacity have been progressed. The actuator for applying BD is also required to have high performances, such as compatibility, slim thickness and 3-axis motion. In this paper, an asymmetric dual lens actuator is proposed to satisfy abovementioned performances. To design the actuator in a limited space, stress analysis and design of experiment (DOE) are performed to reduce weight of moving part and increase driving force and flexible mode frequency. Consequently, the final model, which is satisfied with specifications, is secured.

• Design & Manufacturing
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• 제17권3호
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• pp.61-66
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• 2023

In this study, we developed a simulation methodology for a technology that rapidly cools molds by directly spraying them with CO₂ in its liquefied gaseous state. Initially, a simulation verification process was conducted using ANSYS Fluent's heat transfer analysis based on temperature values measured in prior research experiments, ensuring a comparable temperature could be calculated. Subsequently, the validated analysis method was employed to evaluate design factors that exert the most significant influence on cooling. An evaluation was conducted based on three factors: part thickness, mold thickness, and the melting temperature of material. Using a full factorial design approach, a total of 27 analyses were completed and subsequently calculated through analysis of means. The impact assessment was carried out based on the temperature values at the product's core. The results indicated that the thickness of the mold had the highest influence, while the melting temperature of material had the least.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.248-251
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• 2004

This study was performed to propose the minimum thickness of RC slab that satisfies constructibility, fatigue safety, and serviceability requirements such as deflection control. Three different minimum thicknesses are calculated using concrete shear and rebar fatigue formulas, and deflection control, respectively, and checked by constructiblity. The maximum of these three minimum thicknesses is proposed as the minimum thickness of RC slab, which shows that the minimum thickness requirement of RC slab from Korean Bridge Design Code can be thinner than now.

• 한국산업안전학회:학술대회논문집
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• 한국안전학회 1997년도 추계 학술논문발표회 논문집
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• pp.31-36
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• 1997

Strength test using strain rosette gage have been conducted to investigate safety of an auxiliary tank in a high-pressure air compressor. Thickness of auxiliary tanks in 6063-T5 aluminum at toy are 9mm and 17mm. The result of strength test make a comparison the design in strength of materials by nominal stress and the design in fracture mechanics with consideration of crack size. Summarizing the result: Comparing with the safe working pressure of the strength test and that of the design method in strength of materials by nominal stress with the experimental values, it makes difference 11% and 39% for 9mm and 17mm thickness of auxiliary tanks, respectively, and that of the design method by fracture mechanics, it makes difference 4％ and 5% for them, respectively. It is confirmed that the design by fracture mechanics is more economical and safe design than the design in strength of materials by nominal stress.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.362-365
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• 2007

In wind turbine blades, airfoils are required to have different spec when compared with airplane airfoil. Airfoils for wind turbine blade must have a high lift-to-drag ratio, moderate to high lift and especially low roughness sensitivity. Also an operation Re. No.s are lower than conventional airplane airfoils. At mid-span and inboard region, structural problems have to be considered. Especially, for stall regulated type, moderate stall behavior is essential part of design. For these reasons, airfoil design for HAWT blade is essential part of blade design. In this paper, root airfoil and tip airfoil are discussed. For a root region, 24% thickness airfoil is designed and for a top region, 12% thickness ratio is done. A inverse design method and panel method are used for rapid airfoil design. In this paper, a design method, features of airfoil shape and characteristics are discussed.

• 한국자동차공학회논문집
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• 제5권4호
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• pp.48-69
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• 1997

The use of advanced composite materials in many engineering structures has steadily increased during the last decade. Advanced composite materials allow the design engineer to tailor the directional stiffness and the strength of materials as required for the structures. Design variables to the design engineer include multiple material systems. ply orientation, ply thickness, stacking sequence and boundary conditions, in addition to overall structural design parameters. Since the vibration and impact strength of composite cylindrical shell is an important consideration for composite structures design, the reliable prediction method and design methodology should be required. In this study, the optimum design of composite cylindrical shell for maximum natural frequency, buckling strength and impact strength are developed by analytic and numerical method. The effect of parameters such as the various composite material orthotropic properties (CFRP, GFRP, KFRP, Al-CFRP hybrid), the stacking sequences, the shell thickness, and the boundary conditions on structural characteristics are studied extensively.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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• pp.183-190
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• 1998

In this study, I-type girders, main members of a steel composite bridge, are designed by Load and Resistance Factor Design method as well as Allowable Stress Design method. The width, height web thickness and flange thickness of main girders are set as design variables. The design program connects optimization program ADS, which is coded with FORTRAN, and a main program coded with $C^{++}$. In this study, it is shown that in this particular steel composite bridge, the design by The Load and Resistance Factor Design method is more economical than that by The Allowable Stress Design method.d.