• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.6
• /
• pp.72-79
• /
• 1995

The purpose of this paper is to develop an automatic measuring system based on the digital image processing which can be applied to the in-process measurment of the characteristics of the thin thickness. The derivative operators is used for edge detection in gray level image. This concept can be easily illustrated with the aid of object shows an image of a simple light object on a dark background, the gray level profile along a horizontal scan line of the image, and the first and second derivatives of the profile. The first derivative of an edge modeled in this manner is 0 in all regions of constant gray level, and assumes a constant value during a gray level transition. The experimental results indicate that the developed automatic inspection system can be applied in real situation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1997.03a
• /
• pp.140-143
• /
• 1997

The present study is concerned with the hydrostatic extrusion process of copper-clad aluminium bar to investigate the basic flow characteristics. Considering the bonding mechanism of bi-metal contact surface as cold pressure welding, the normal pressure and the contact surface expansion are selected as process parameters governing the bonding condition. The critical pressure required for the bonding at the interface is obtained by solving a "local extrusion" using a slip line meyhod. A viscoplastic finite element method is used to analyze the steady state extrusion process. The boundary profile of bi-metal rod is predicted by tracking a particle path adjacent to interface surface. The variations of contact surface area and the normal pressure along the interface profile are predicted and compared to those by experiments.

• Proceedings of the Korean Society of Laser Processing Conference
• /
• 2005.06a
• /
• pp.3-8
• /
• 2005

The robot systems are widely used in the welding manufacturing. The essential tasks to operate the welding robot are the acquisition of the position and/or shape of the parent metal. For the seam tracking or the robot automation, many kinds of contact and non-contact of the system which monitors the shape of the welding part is described. This system uses the line-type structured laser diode and the visual sensor. It includes the correction of radial distortion which is often found in the image from the camera with short focal length. Direct Linear Transformation (DLT) is used for the camera calibration. The three dimensional shape of the parent metal is obtained after simple linear transformation. Therefore, the system operates in real time. Some experiments are carried out to evaluate the performance of the developed system.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.14 no.2
• /
• pp.39-44
• /
• 2006

The unsteady vortex lattice method is used to model lead-lag in flapping motions of a rectangular flat plate wing. The results for plunging and pitching motions were compared with the limited experimental results available and other numerical methods. They show that the method is capable of simulating many of the features of complex flapping flight. The lift, thrust and propulsive efficiency of a rectangular flat plate wing have been calculated for various lead-lag motion and reduced frequency with an amplitude of flapping angle(20o). To describe a motion profile of wing tip such as elliptic, line and circle, the phase difference of flapping and lead-lag motion was changed. And the effects of the motion profile on the aerodynamic characteristics of the flapping wing are discussed by examination of their trends.

• Journal of the Korean Data and Information Science Society
• /
• v.15 no.1
• /
• pp.251-261
• /
• 2004

The paper focuses primarily on the standard linear multiple regression model where the parameter of interest is a ratio of two regression coefficients. The general model includes the calibration model, the Fieller-Creasy problem, slope-ratio assays, parallel-line assays, and bioequivalence. We provide an orthogonal transformation (cf. Cox and Reid (1987)) of the original parameter vector. Also, we give some remarks on the difficulties associated with likelihood based confidence interval.

• Proceedings of the KIEE Conference
• /
• 1998.07c
• /
• pp.1063-1065
• /
• 1998

This paper discusses the selection of optimal location of Thyristor Controlled Series Compensator (TCSC) devices to maintain the steady-state voltage profile within limits. A procedure for selecting optimal TCSC location based on sensitivity analysis is developed. This approach identifies the critical lines by evaluating all the voltage magnitudes sensitivity with respect to a line reactance. Computer simulation of a example system is used to verify the proposed procedure.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.934-939
• /
• 2004

Railway wheel/rail contact conditions have an influence on dynamic behavior of rolling stock. If there are problems of incompatibility between wheel and rail, damages like wheel wear, wheel spalling, rail wear, etc are occurred. Especially wheel and rail profiles are important factor of vehicle curving performance, so compatibility study between wheel and rail has to be carried out preferentially, In this study, we have analyzed the compatibility between wheel and rail of KNR conventional line to improve the maintenance efficiency of wheel and rail. Thus we showed the results relating to wheel/rail geometric contact, vehicle running performances as the change of wheel/rail combination.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.33 no.8
• /
• pp.559-564
• /
• 2009

The variation in the shape of water droplet moving on atomistically smooth solid surface in the presence of a constant body force is simulated using molecular dynamics simulation. We investigated how the advancing and receding contact angle of the moving water droplet changes on a solid surface having various characteristic energies. From the MD simulation results, we obtained the density profile defined as the number of water molecules at a given position. Then, assuming the water droplet periphery to be a circle, we calculated the contact angles by using a nonlinear fitting of the half-density contour line. The present simulation clearly shows the different profile of the advancing and receding contact angle for these three different interaction potential between the water droplet and the solid surface.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.09c
• /
• pp.31-36
• /
• 2010

This paper introduces a practical determination method for soil parameters adopted in the new performance based design code for port and harbour facilities in Japan. In the new port-design code, the depth profile of the derived values is modeled as the profile of the estimated values so as to be either the mean value or the regression line, then the correction factors are multiplied to the estimated value according to the coefficient of variation (if COV > 0.1) and the number of the data entries (if n < 10). The new port-design code is applied to the unconfined compression test results for the Hiroshima Port clay in order to evaluate the undrained shear strengths. From the discussion, it is emphasized that not only the statistic treatment but also the engineering judgment are required in the procedure of the soil parameter determination for the reliability design.

• Korean Journal of Veterinary Research
• /
• v.35 no.3
• /
• pp.625-630
• /
• 1995

During the period from june 1994 to february 1995 influence of free stall with concrete floor on profile of blood chemistry and clinico-morphopathogenesis of foot disease on 266 cows were studied. The results obtained as follow. 1. No differences between value of blood chemistry in normal and lame cows with foot disease were observed. 2. 20.7% of the cows were clinically lame. 3. Prevalence of clinical digital disorders were investigated: hyperplasia interdigitalis(45.8%), pododermatitis circumscripta(22.4%), dermatitis interdigitalis(9.4%), erosio ungulae(5.9%), phlegmona interdigitalis(3.5%), pododermatitis septica traumatica(3.5%), dermatitis digitalis(2.4%), white line disease(2.4%), pododermatitis aseptica diffusa(2.4%), dermatitis verrucosa(1.2%), fissura ungulae(1.2%) 4. Most claw lesions were located on lateral hindclaws and interdigital space of hindclaws.