• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.95-99
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• 1996

The form accuracy of parts has become an important parameter. Therefore dimensional tolerance and geometric tolerance are used in design to satisfy required quility and functions of parts. But the informations for machining conditions, which can satisfy the assigned geometric tolerance in design, are insufficient. The objectives of this research are to study the effects of the grinding parameters such as traverse speed, work speed, depth of cut, and dwell time on the after-ground workpiece shape, and to find out the major parameters among these parameters. Finally, a methodology is proposed for getting the optimal grinding condition for precision workpiece The results are as follows; The effects of work speed and depth of cut on workpiece shape are ignorable compared to the effect of traverse speed. These is the optimal dwell time depending on the traverse speed. The optimal dwell time is decreasing when the traverse speed is increased.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2097-2101
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• 2007

This paper presents an optimal design of a micro evaporator which maximizes the heat transfer coefficient. Number of gaps, spanwise distance and streamwise distance are selected as the geometric design parameters. Mass flow rate of the refrigerant is selected as the non-geometric design parameter. Temperature at the surface of the heater is measured to valuate the heat transfer coefficient. Nine experiments are conducted using $L_9(3^4)$ orthogonal array. Maximum heat transfer coefficient is 640 W/$m^2K$ at the parameters of 2 gaps, 0.2 mm spanwise distance, 1.0 mm streamwise distance and 0.72 g/s mass flow rate. Among the 3 geometric parameters, the spanwise distance is the most sensitive parameter influencing the heat transfer coefficient. We conduct a second stage of experiment to increase the heat transfer coefficient by reselecting the mass flow rate. We concluded that 0.87 g/s is the optimized flow rate for an active micro cooler resulting in a heat transfer coefficient of 651 W/$m^2K$.

• 대한기계학회논문집B
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• 제28권10호
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• pp.1231-1237
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• 2004

Determination of geometric design parameters of a second-throat type annual supersonic ejector is described. Tested geometric parameters were primary nozzle area ratio, cross-sectional area of second-throat, L/D ratio of second-throat and primary flow injection angle. Varying these four geometric parameters, we build a test matrix made of 81 test conditions, and experimental apparatus was fabricated to accommodate them. For each test condition, the stagnation pressure of primary flow and the static pressure of the secondary flow were measured simultaneously along with their transition to steady operation and finally to unstarting condition. Comparing the performance curve of every case focused on starting pressure, the unstarting pressure and the minimum secondary pressure, we could derive correlations that the parameters have on the performance of the ejector and presented the optimal design method of the ejector. Additional experiments were carried out to find effects of temperature and mass flow rate of the secondary flow.

• 한국정밀공학회지
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• 제10권4호
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• pp.236-247
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• 1993

An davanced method for the automatic generation of parametric models in computer- aided design systems is required for most of two-dimensional model which is represented as a set of geometric elements, and constraining scheme formulas. The development system uses geometric constraints and support of topology parameters from feature recognition and grouping the design entities into optimal ones from pre-designed drawings. The aim of this paper is to present guidelines for the application and development of parametric design modules for the standard parts in mechanical system, the basic constitutional part of mold base, and other 2D features.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권1호
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• pp.75-87
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• 2012

A design paradigm using sequential geometric programming is presented to accurately design CMOS op amps with BSIM3. It is based on new adaptive modeling of transistor parameters through the operating point simulation. This has low modeling cost as well as great simplicity and high accuracy. The short-channel dc, high-frequency small-signal, and short-channel noise models are used to characterize the physical behavior of submicron devices. For low-power and low-voltage design, this paradigm is extended to op amps operating in the subthreshold region. Since the biasing and modeling errors are less than 0.25%, the characteristics of the op amps well match simulation results. In addition, small dependency of design results on initial values indicates that a designed op amp may be close to the global optimum. Finally, the design paradigm is illustrated by optimizing CMOS op amps with accurate transfer function.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.413-414
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• 2002

An automotive wheel bearing is one of the most important components to guarantee the service life of a passenger car. The endurance life of a bearing is affected by many parameters such as material properties, heat treatment, lubrication conditions temperature loading conditions, bearing geometry, internal clearance and so on. In this paper, we calculate the endurance life of wheel bearing units and analyze the sensitivity of bearing geometric parameters on the life by using Taguchi method.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.275-281
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• 2001

While basic input parameters for the performance and noise of axial fan are flow rate, pressure rise, rotating speed, and fan diameter, the geometric parameters of blade are sweep angle, solidity, and camber angle. The sweep angle does not affect fan performance much, but on fan noise significantly. Solidity and camber angle are very critical design parameters acting on the fan performance directly. The solidity and camber angle are closely related, therefore they have to be carefully determined for the low-noise and high-performance fan. In This paper, different design points are selceted and also geometric parameters are deliberately changed for the comparison of fan noise. As a result, at the same performance, the input rotational speed affects radiated noise more significantly than others. When solidity and camber angle are increased more than those by iDesignFan／sup TM／ program, more noise is experienced. The blade sweep method and blade numbers at same solidity are observed to results in different levels of performance and noise.

• 대한기계학회논문집A
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• 제33권8호
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• pp.726-732
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• 2009

In many industries, the linear motor replaces the existing framework for linear transportation. Similar to other conventional motors, it is important to minimize the ripple of thrust and to maximize the thrust force of the linear motor. Because the two objectives are associated to each other, the multi-objective design process is necessary considering all objectives. This paper intends to optimize geometric parameters of the linear motor with two design objectives using design of experiments and sequential response surface method.

• International Journal of Control, Automation, and Systems
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• 제1권3호
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• pp.351-357
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• 2003

A method of design optimization for minimization of force ripple and maximization of thrust force in a linear brushless permanent magnet motor without finite element analysis is represented. The design optimization method calculated the driving force in the function of electric and geometric parameters of a linear brushless PM motor using the sequential quadratic programming method. Using electric and geometric parameters obtained by this method, the normalized force ripple is reduced 7.7% (9.7% to 2.0%) and the thrust force is increased 12.88N (111.55N to 124.43N) compared to those not using design optimization.

• 한국생산제조학회지
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• 제22권6호
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• pp.1018-1024
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• 2013

In the process of draw die design for stamping automotive press panels, the addendum surfaces generated in metal forming simulation software cannot be used in downstream processes such as machining and making draw dies because simulation tools use simple discrete models for the surface geometry. The downstream processes require more precise and continuous geometric models such as NURBS surfaces. Generally, automotive die engineers manually regenerate the addendum surface geometry using the discrete model. This paper presents an automated geometric modeling process for generating addendum surfaces using draft surface models. The design parameters of the section curve for the addendum surfaces are extracted automatically from the draft geometry. Using the extracted design parameters, smooth addendum surfaces are generated automatically as NURBS surfaces. The generated surfaces are $G^1$ continuous with the part surface and the binder surface, and can be used in downstream processes.