• Journal of Advanced Marine Engineering and Technology
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• v.28 no.8
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• pp.1185-1194
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• 2004

Virtual images for PIV are produced for the construction of a benchmark test tool of PTV systems, Camera parameters obtained by an actual experiment are used to construct the virtual images, LES(Large Eddy Simulation) data sets of a channel flow are used for generation of the virtual images, Using the virtual images and the camera's parameters. three-dimensional velocity vectors are obtained for a channel flow. The capabilities of a 3D-PTV algorithm are investigated by comparing the results obtained by the virtual images and those by an actual measurement for the channel flow.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.3
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• pp.110-116
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• 2002

Here are shown on stress and vibration evaluations and application of piping system in petrochemical plant with and actual example. While stress evaluation by thermal growth has no argument on the calculated results, vibrational evaluations have some different results in accordance with the evaluation methods. In case of the static stress evaluation the ASME B3l.3 code defines 7000 cycles of fatigue lift: in operating the piping system with a design condition. However, the method of vibrational evaluation on piping systems in petrochemical plants has not been established clearly, yet. In this stuffy, it is purposed to present the requirement of a vibrational evaluation method for petrochemical plant piping system, with an actual application.

• Journal of Korea Multimedia Society
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• v.19 no.4
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• pp.774-779
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• 2016

The conventional methods using color signal for tracking the movement of the object require a lot of calculation and the performance is not accurate. In this paper, we propose a method to effectively track the moving objects using the depth information from a depth camera. First, it separates the background and the objects based on the depth difference in the depth of the screen. When an object is moved, the depth value of the object becomes blurred because of the phenomenon of Motion Blur. In order to solve the Motion Blur, we observe the changes in the characteristics of the object (the area of the object, the border length, the roundness, the actual size) by its velocity. The proposed algorithm was implemented in the simulation that was applied directly to the tracking of a golf ball. We can see that the estimated value of the proposed method is accurate enough to be very close to the actual measurement.

• Journal of Biosystems Engineering
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• v.19 no.4
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• pp.301-310
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• 1994

The feasibility of using ultrasonic-wave doppler sensors for a measurement of the actual ground speed of agricultural machines was investigated. The actual ground speed is estimated from the doppler shift frequencies of the two ultrasonic-waves transmitted to and received from a moving object. A prototype of the speed-measurement system was designed and constructed for the performance test. The measurement system showed a good performance with a flat surface at speeds lower than 3m/s. However, it was failed to receive the reflected signals from the rough and irregular soil surfaces. Further researches to solve this problem and to improve its performance are now underway.

• Journal of Ocean Engineering and Technology
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• v.22 no.3
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• pp.58-63
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• 2008

A 32-ft class leisure boat was newly developed using statistical analysis of actual ships. Resistance performances were investigated by testing models in a high-speed circulating water channel, and with the CFD method. The effects of a trim tab and of a fin attached at the hull side were studied together. Wave patterns were observed to clarify the relationship between resistance performance and wave characteristics. It was found that a trim tab and a side fin play a role in increasing resistance performance within a certain velocity range.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.337-342
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• 2002

A new apparatus called the EFA (Erosion Function Apparatus) has been built and tested to measure the erodibility of fine-grained soils. The EFA is a simple test to predict the erosion rate of fine-grained soils along with the corresponding velocity and shear stress. In addition, it is advantageous in predicting the scour rate for actual soil samples from bridge sites. The plot of erosion rate versus shear stress is the result of an EFA test. It Indicates the critical shear stress at which erosion starts and the rate of erosion beyond that shear stress. In order to measure the erodibilities of various soils, 14 Shelby Tube soil samples are collected from the actual bridge sites and tested using the EFA. The results of the EFA tests which are the relationships between erosion rates and shear stresses are presented in this paper and research continues to develop the correlation between the erosion function and the soil properties.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2797-2802
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• 2007

It has been confirmed that implementation of the no-slip boundary conditions for the lattice-Boltzmann method play an important role in the overall accuracy of the numerical solutions as well as the stability of the solution procedure. We in this paper propose a new algorithm, i.e. the method of the dynamic boundary condition for no-slip boundary condition. The distribution functions on the wall along each of the links across the physical boundary are assumed to be composed of equilibrium and nonequilibrium parts which inherit the idea of Guo's extrapolation method. In the proposed algorithm, we apply a dynamic equation to reflect the computational slip velocity error occurred on the actual wall boundary to the correction; the calculated slip velocity error dynamically corrects the fictitious velocity on the wall nodes which are subsequently employed to the computation of equilibrium distribution functions on the wall nodes. Along with the dynamic selfcorrecting process, the calculation efficiently approaches the steady state. Numerical results show that the dynamic boundary method is featured with high accuracy and simplicity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.1
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• pp.131-138
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• 1998

Conventional yaw functions are compared with actual response of a hot wire to various yaw angles, and a new function is proposed, which can be applied at large yaw angles and low velocities. To compare the accuracy of the new yaw function with those of the conventional ones, measurements are made for the jet flow at the nozzle exit and at .chi./D=15 with an X hot-wire probe. In the potential core, the flow angles reduced by the present function, ideal angle method and full velocity-angle method are shown to be more accurate than those reduced by the cosine function and Hinze's formula. No matter which yaw functions are used, the profiles of mean velocity and turbulence intensity show little discrepancy at .chi./D=15. However, there is a significant difference between the probability density functions obtained by the present function, ideal angle method and full velocity-angle method and those obtained by the cosine function and Hinze's formula.

• Transactions of Materials Processing
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• v.24 no.4
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• pp.227-233
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• 2015

In this paper, the effect of flow stress, friction, temperature, and velocity on finite element predictions of metal flow lines after cylindrical upsetting is presented. An actual three-stage hot forging process involving an upsetting step is utilized and experimental metal flow lines are measured to study the effect of the various process variables. It was found that temperature and velocity for reasonable values of friction have little influence on metal flow lines especially those located deep within the cylinder but that flow stress has a direct influence on the flow lines. It was shown that a pure power law material model cannot reflect the real flow stress of hot material because it underestimates the flow stress especially around the dead-metal zone for the upsetting of a cylindrical specimen. It is thus recommended that a proper lower limit of flow stress be assumed to alleviate this issue.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.3
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• pp.206-214
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• 2015

In this study, low-velocity impact damage (LVID) in glass fiber reinforced plastic (GFRP) was investigated using pulse thermography (PT) and lock-in thermography (LIT) techniques. The main objective of this study was to evaluate the detection performance of each technique for LVID in GFRP. Unidirectional and cross-ply GFRPs were prepared with four energy levels using a drop weight impact machine and they were inspected from the impact side, which may be common in actual service conditions. When the impacted side was used for both inspection and thermal loading, results showed that the suggested techniques were able to identify the LVID which is barely visible to the naked eye. However, they also include limitations that depend on the GFRP thickness at the location of the delamination produced by the lowest impact energy of five joule.