• Journal of Mechanical Science and Technology
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• v.16 no.3
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• pp.395-402
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• 2002

This paper shows how to formulate the transient analysis of 2-dimensional Hagen-Poiseuille flow using smoothed particle hydrodynamics (SPH). Treatments of viscosity, particle approximation and boundary conditions are explained. Numerical tests are calculated to examine effects caused by the number of particles, the number of particles per smoothing length, artificial viscosity and time increments for 2-dimensional Hagen-Poiseuille flow. Artificial viscosity for reducing the numerical instability directly affects the velocity of the flow, though effects of the other parameters do not produce as much effect as artificial viscosity. Numerical solutions using SPH show close agreement with the exact ones for the model flow, but SPH parameter must be chosen carefully Numerical solutions indicate that SPH is also an effective method for the analysis of 2-dimensional Hagen-Poiseuille flow.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.7
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• pp.970-976
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• 2004

For a long time, design methodologies strive to systematize the design process in order to make the practice more efficient and effective. One of such methodologies is Axiomatic Design. However, this design theory still has some problems and is not completely settled. In this paper, the new issue for the non-linear design in Axiomatic Design is suggested and the representation of system architecture by flow chart is corrected. In the case that the design equation varies as a function of the variation of DP ($\delta$DP), the design should be regarded as the nonlinear design because the design equation is not a constant. When system architectures are represented by a flow chart, all systems could not be independently represented. However, by adding the notation of the end of decoupling to the notations using in flow chart, those can be independently represented.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.51-58
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• 2001

The use of tailor welded blanks (TWB) in automotive applications is increasing due to the potential of weight and cost saving. The object of this study is development of the front side member by static analysis and crash simulations. Accord-ing to the results , energy absorption and barrier force is very important parameter to control passenger safety and deforma-tion shape. A energy absorbability point of view, tailor welded blanks is most effective to absorb energy than non-twb. Non-TWB front side member and TWB applied front side member were simulated. It shows reduce stmping parts weight reduction and cost down.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.504-509
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• 2001

CD-ROM drive is improved in rotation speed up to 10,000 rpm. But Vibration and Noise are also increased simultaneously more and more. So many attempts are tried to reduce the unexpected effects. Most attempts are not enough to cover the increasement of Noise and Vibration. Merely availed tries are accumulated in many part and it makes the structure complicated. The Axiomatic approach could arrange the order of design and estimate the optimum design in good oder. In Axiomatic Approach, the composition is divided by Customer Requirement, Functional Requirement, Design Parameter and Design Matrix in large portion. This method also could show more effective way to design before making a prototype.

• Journal of KSNVE
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• v.8 no.5
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• pp.887-899
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• 1998

It has been resulted that Lagrange multiplier method with statistical approach was superior to traditional harmonic balance method in identifying the nonlinear loudspeaker parameters when output signals were contaminated with Gaussian random noise. We have known that the displacement-dependent characteristic values of nonlinear parameters identified by traditional harmonic balance method were estimated less than original values by the increase of output noise and the stiffness coefficients were very sensitive to output noise. Also, by the sensitivity analysis we have verified that the harmonic distortions in acoustic radiation was mainly due to nonlinearity of force factor caused by uneven magnetic fields and that reducing the nonlinearity of damping coefficients were very effective for improving second harmonic distrotion of acoustic radiation.

• Korean journal of food and cookery science
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• v.11 no.1
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• pp.83-91
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• 1995

For the accurate interpretation and objective measurement of textural characteristics of fermented vegetables, first of all, the studies on the microstructure and chemical compositions of vegetable cell, and the changes in the textural properties of vegetables during salting, blanching and fermentation should be carried out. And the mechanical textural parameters were needed to compare with and analyze in relation to the sensory parameters. In this review, the thypical force-distance curves of fermented vegetables were obtained from the compression, cutting and puncture test. And it was showed that the compression force was a more effective textural parameter to express the hardness of fermented vegetables, and the sensory chewiness and toughness were related to the changes in cutting force. In the puncture test, the puncture force was related to the hardness and varied with the size and form of puncture probe; the changes in puncture force by small probe could express the decrease in hardness and crispness, whereas those by large probe could represent the changes in toughness. And the brittleness and crispness could be measured by the break point and the numbers of peak obtained from the force-distance curves.

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.105-116
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• 2005

This study investigated the applicability of the Artificial Neural Network(ANN) technique for prediction of tunnel behavior. For training data collection, a series of finite element analyses were conducted for actual tunnel project site. Using the data, optimimzed ANNs were developed through a sensitivity study on internal parameters. The developed ANNs can make tunneling related predictions such as tunnel crown settlement, shotcrete lining stress, ground surface settlement, and groundwater inflow rate. The results indicated that the developed ANNs can be used as an effective and efficient tool for tunnelling related prediction in practical tunneling situations.

• Korean Journal of Computational Design and Engineering
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• v.4 no.1
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• pp.69-77
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• 1999

This paper describes an expert system of progressive die. Because of the complexity for die structure and of the critical problems for press machine mechanism in the progressive press process such as, the travel length in process, the equalized press load, and the other design parameter, it has been increased the requirement of the CAD system for progressive die design more an more. So, through this study, an expert system of progressive die has been developed. The results from the system developed were suggested the possibility of applications in the practice. To develop this system, it has used c-language under the HP-UNIX system and CIS customer language of the EXCESS CAD/CAM system. An application of this system will provide effective aids to the designer in this field.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.5
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• pp.500-510
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• 2013

In this paper, a high-sensitivity low power photodetector using double gate (DG) MOSFET is proposed for the first time using change in subthreshold current under illumination as the sensitivity parameter. An analytical model for optically controlled double gate (DG) MOSFET under illumination is developed to demonstrate that it can be used as high sensitivity photodetector and simulation results are used to validate the analytical results. Sensitivity of the device is compared with conventional bulk MOSFET and results show that DG MOSFET has higher sensitivity over bulk MOSFET due to much lower dark current obtained in DG MOSFET because of its effective gate control. Impact of the silicon film thickness and gate stack engineering is also studied on sensitivity.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.332-335
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• 1995

A simple and effective method for improving Euclidean norm condition number for chemical processing system is presented. The singular value sensitivities of Freudenberg et al. (1982) is used to estimate the behavior of singular values of process transfer function matrix when design parameter is changed, then the condition number can be calculated straightforwardly. The method requires explicit dependencies of each transfer function matrix elements on design parameters. These dependencies can be obtained either by symbolic differentiation in the form of explicit function of design parameters, or by numerical perturbation studies for units with large and complicated models. Gerschgorin-type lower bound for minimum singular value is introduced to detect the large divergencies near singular point due to linearity of sensitivities. The case studies are performed to show the efficiency of the proposed method.