• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.8
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• pp.519-525
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• 2016

In a pump, from the performance point of view, it is very important to minimize the shock loss at the inlet of the rotor blades. In this study, the effects of shape and install angle of the inlet guide on the performance of an axial-flow pump are numerically simulated using commercial CFD code, Ansys CFX. Finally, to obtain the optimized shape of the vanes and the install angle of the vanes in the inlet guide under given operating conditions, optimization analysis is conducted using Analysis design exploration based on response surface optimization.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.3
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• pp.37-43
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• 2004

Engine lubrication system is generally affected by vehicle driving conditions; acceleration, braking deceleration, and cornering. The oil supply system such as oil pan, baffle plate, and oil pick-up pipe should be optimized to cope with severe driving conditions. The main purpose of this paper is to understand the effect of the engine tilting angle on the oil supply system using engine tilting test rig. For the purpose, the oil pressure fluctuation and oil aeration in the main gallery are measured at various engine tilting angles. In addition, the oil flow is visualized by using transparent oil pan to investigate the cause of the formation of oil aeration. The test results show there is a strong correlation between the main gallery oil pressure fluctuation and oil aeration. It is also found that the visualization technique is helpful to stabilize the oil supply system at severe driving conditions.

• Journal of Information Display
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• v.1 no.1
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• pp.3-8
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• 2000

We have developed a high performance vertical alignment TFT-LCD (Thin Film Transistor Liquid Crystal Display), that shows a high light transmittance, and wide viewing angle characteristics with an unusually high contrast ratio. In order to optimize the electro-optical properties we have studied the effect of cell parameters, multi-domain structure and retardation film compensation. With the optimized cell parameters and process conditions, we have achieved a 24" wide UXGA TFTLCD monitor (16:10 aspect ratio 1920X1200) showing a contrast ratio of over 500:1, panel transmittance near 4.5%, response time near 25 ms, and viewing angle higher than 80 degree in all directions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04b
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• pp.42-44
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• 2002

The experimental model of the 8-view stereoscopic display system using the photopolymer-based VHOE is proposed. At first, the VHOE is implemented by angle-multiplexed recording of 8-view's diffraction gratings using the optimized exposure-time scheduling scheme in the photopolymer (HRF-150-100) and then. the VHOE-based 8-view stereoscopic display system is implemented by sequentially synchronizing the incident angles of the reference beam of the VHOE with the 8-view stereo images on the LCD pannel. Accordingly, from some experimental results using 8-view images generated by the toed-in stereo camera system, it is found that 8-view stereo images can be diffracted to eight different directions time-sequentially and there is some disparity between the stereo images.

• Structural Engineering and Mechanics
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• v.57 no.4
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• pp.763-783
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• 2016

A methodology based on Teaching Learning-Based Optimization (TLBO) algorithm is proposed for optimum design of reinforced concrete retaining walls. The objective function is to minimize total material cost including concrete and steel per unit length of the retaining walls. The requirements of the American Concrete Institute (ACI 318-05-Building code requirements for structural concrete) are considered for reinforced concrete (RC) design. During the optimization process, totally twenty-nine design constraints composed from stability, flexural moment capacity, shear strength capacity and RC design requirements such as minimum and maximum reinforcement ratio, development length of reinforcement are checked. Comparing to other nature-inspired algorithm, TLBO is a simple algorithm without parameters entered by users and self-adjusting ranges without intervention of users. In numerical examples, a retaining wall taken from the documented researches is optimized and the several effects (backfill slope angle, internal friction angle of retaining soil and surcharge load) on the optimum results are also investigated in the study. As a conclusion, TLBO based methods are feasible.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1203-1208
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• 2009

In this paper, the flow characteristics of the mixed-flow pump impellers and diffusers were numerically predicted by commercial CFD software and DOE(design of experiments). We also discussed how to improve the performance of the mixed-flow pump by designing the impeller and diffuser in the mixed-flow pump. Geometric design variables were defined by the vane plane development which indicates the blade-angle distributions and length of the impeller and the diffusers. Firstly, the design optimization of the defined impeller geometric variables has been done. After that, the flow characteristics were analyzed in the point of incidence angle at the diffuser leading edge for the optimized impeller. Then design of the defined diffuser shape variables has been performed. The reason for the performance improvement was discussed by examining the flow characteristics through the diffuser.

• Current Optics and Photonics
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• v.1 no.3
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• pp.214-220
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• 2017

A wavelength filter based on a polymer Bragg reflector has received much attention due to its simple structure and wide tuning range. Tilted Bragg gratings and asymmetric Y-branches are integrated to extract the reflected optical signals in different directions. To optimize device performance, design procedures are thoroughly considered and various design parameters are applied to fabricated devices. An asymmetric Y-branch with an angle of $0.3^{\circ}$ produced crosstalk less than -25 dB, and the even-odd mode coupling was optimized for a grating tilt angle of $2.5^{\circ}$, which closely followed the design results. Through this experiment, it was confirmed that this device has a large manufacturing tolerance, which is important for mass production of this optical device.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.171-178
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• 2000

In order to evaluate the tensile behaviors of hoop direction for the nuclear fuel cladding tubes the shapes of specimen and jig fixtures for the ring test are decided with various conditions under the elastic-large plastic deformations. The axial displacement of the jig cylinders is converted to the circumferential direction elongations of specimen. The stress distributions on specimen are depended on the radii and locations of specimen and jig size and central angle. Therefore we calculated the stress distributions and decided the optimum shapes to get the uniform stress in the area of specimen gage length. Form the analysis the stress distributions in gate area are reviewed with the radii and location of specimen notch and the central angle of jig cylinder,. The optimum shapes of specimen and jig are proposed to the clad tube having 10.62 mm in diameter and 0.63mm in thickness for 16x16 PWR nuclear fuel assembly.

• Structural Engineering and Mechanics
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• v.65 no.4
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• pp.447-452
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• 2018

The controlling and prediction of spring back is one of the most important factors in sheet metal forming processes which require high dimensional precision. The relationship between effective parameters and spring back phenomenon is highly nonlinear and complicated. Moreover, the objective function is implicit with regard to the design variables. In this paper, first the influence of some effective factors on spring back in U-die bending process was studied through some experiments and then regarding the robustness of artificial neural network (ANN) approach in predicting objectives in mentioned kind of problems, ANN was used to estimate a prediction model of spring back. Eventually, the spring back angle was optimized using the Imperialist Competitive Algorithm (ICA). The results showed that the employment of ANN provides us with less complicated and time-consuming analytical calculations as well as good results with reasonable accuracy.

• Journal of Biomedical Engineering Research
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• v.26 no.6
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• pp.365-372
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• 2005

Topology optimization method has a great advantage and capability over a conventional shape optimization technique because it optimizes a topology as well as a shape and size of structure. The purpose of the present study, using topology optimization method with an objective function of minimum compliance as a mechanism of bone remodeling, is to examine which shape factors of femur is strongly related with the curvature of femoral shaft. As is expected, the optimized curvature increased definitely with neck angle among the shape factors and showed a similar trend with the measured curvature to neck angle. Therefore, the topology optimization method can be successfully applied in the analysis of bone remodeling phenomenon in the subsequent studies.