• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.4
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• pp.295-300
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• 2016

In the design of passive and active boring bars, the structural dimensions and shape of the vibration control boring bar are modified depending on the diameter and depth of the workpiece, which changes the dynamic behavior. Thus, the natural frequency, effective mass, and stiffness for the main structure of a tube-type boring bar need to be reset for each vibration control case. However, commercial finite element method (FEM) software and experimental modal analysis are mostly used at present despite being too time-consuming. To overcome the weaknesses of the two methods currently used for vibration control, we realized a graphical user interface (GUI) program for the modal analysis of a modified tube-type damping structure. The analysis results with the GUI program were compared to those with commercial FEM software in order to confirm the effectiveness of the former.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.563-568
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• 2007

A separate triangular bar type differential pressure flow meter was developed for measuring exhaust gas flow rate from Diesel engine. Three kinds of the separate triangular bar flow meters whose aerodynamic angles are different one another are made and evaluated, respectively. The experimental results show that an aerodynamic shape has a effect on the pressure difference between upstream and downstream at the flow meter, that is, the thinner the shape of the separate triangular bar flow meter is, the smaller the pressure difference at the flow meter is. The separate triangular bar type flow meter was calibrated at both cold and high temperature of the gas flow. A burner system was designed for raising the gas temperature and it was well operated in controlling the gas temperature. An empirical correlation between mass flow rate and differential pressure at the separate triangular bar flow meter was obtained and the empirical correlation was also corrected by the gas temperature.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.4
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• pp.375-390
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• 2009

Statement of problem: Implant supported overdenture is accepted widely as a way to restore edentulous ridge providing better retention and support of dentures. Various types of attachment for overdenture have been developed. Purpose: The purpose of this study was to investigate the influence of attachment type in implant overdentures on the biomechanical stress distribution in the surrounding bone, prosthesis and interface between implant and bone. Material and methods: Finite element analysis method was used. Average CT image of mandibular body(Digital $Korea^{(R)}$, KISTI, Korea) was used to produce a mandibular model. Overdentures were placed instead of mandibular teeth and 2mm of mucosa was inserted between the overdenture and mandible. Two implants($USII^{(R)}$, Osstem, Korea) were placed at both cuspid area and 4 types of overdenture were fabricated ; ball and socket, Locator, magnet and bar type. Load was applied on the from second premolar to second molar tooth area. 6 times of finite element analyses were performed according to the direction of the force $90^{\circ}$, $45^{\circ}$, $0^{\circ}$ and unilateral or bilateral force applied. The stress at interface between implants and bone, and prosthesis and the bone around implants ware compared using von Mises stress. The results were explained with color coded graphs based on the equivalent stress to distinguish the force distribution pattern and the site of maximum stress concentration. Results: Unilateral loading showed that connection area between implant fixture and bar generated maximum stress in bar type overdentures. Bar type produced 100 Mpa which means the most among 4 types of attachments. Bilateral loading, however, showed that bar type was more stable than other implants(magnet, ball and socket). 26 Mpa of bar type was about a half of other types on overdenture under $90^{\circ}$ bilateral loading. Conclusions: In any directions of stress, bar type was proved to be the most vulnerable type in both implants and overdentures. Interface stress did not show any significant difference in stress distribution pattern.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.3
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• pp.189-196
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• 2004

The RC wale-steel beam stud connection may have smaller moment and shear resistance because the tensile and shear capacity of the studs are limited by the depth of RC beam. Especially, they are subjected to compressive axial load. This paper describes the experimental works to develop the connection details of RC wale-steel beam joints subjected to shear and axial loads. Shear connectors developed in this study are closed C type deformed bar, opened C type deformed bar, and U type deformed bar. From shear test, the shear performance of RC wale-steel beam joint with the developed connectors are compared with the stud connection. Test results indicated that the developed connectors were very effiecive to increase the shear strength.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.112-121
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• 2013

FRP reinforced lightweight concrete structures can offer corrosion resistance and weight reduction effect simultaneously, so practical use of the structures may be expected afterwards. But to make concrete structures using lightweight concrete and FRP bar, that can resist external forces without internal slip of the FRP bar, it is very important to understand bond characteristic between lightweight concrete and FRP bar. During that time, a lot of studies for bond behaviors of FRP bar in normal concrete were conducted, but studies for bond behavior of FRP bar in lightweight concrete are very limited to date. So, bond characteristic between lightweight concrete and helically deformed GFRP bar was investigated in this study. Three main parameters were considered in experimental investigation: type of rebar, concrete type, and compressive strength of lightweight concrete. As an experimental result, it could be known that bond strength of helically deformed GFRP bar in lightweight concrete was 0.49 times bond strength of steel reinforcement in normal concrete.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.35.3-36
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• 2016

We explore the role of bars in AGN-galaxy co-evolution using a volume-limited face-on late-type galaxy sample with $M_r$ < -19.5 and 0.02 < z < 0.055 selected from SDSS DR7. In this study, we investigate how $SFR_{fib}$ as a proxy of gas contents at galactic center (over 1~1.5 kpc bulge scale) and central stellar velocity dispersion, ${\sigma}$, of host galaxies are connected to the bar presence and AGN activity. We find that galaxies are distributed in three distinct regions over the $SFR_{fib}-{\sigma}$ space and the behaviors of their bar fraction ($f_{Bar}$) are clearly different for each region. Galaxies at the AGN dominant region tend to be gas-deficient as $f_{Bar}$ increases and bars are more frequently found in fully-quenched late-type galaxies at the quiescent region, suggesting that bars speed up of the consumption of gas by SF and lead a sudden decline in the central gas. Overall, the bar effects on the AGN activity are positive over the same space except for quiescent galaxies with ${\sigma}$ > $170km\;s^{-1}$. Most significant bar effect on the AGN activity occurs in the less massive galaxies having sufficient gas, whereas the effect on galaxies at the AGN dominant region with higher the AGN fraction is relatively small. We suggest that the bar affect both central SF and AGN activities, but differently for central gas amount and BH (or bulge) mass of galaxies. We also investigate the AGN-bar connection with only pure AGNs and then confirm that they give marginally the same results.

• Computers and Concrete
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• v.22 no.2
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• pp.249-259
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• 2018

This paper presents Artificial Neural Network (ANN) models for evaluating bond strength of deformed, plain and cold formed bars in low strength concrete. The ANN models were implemented using the experimental database developed by conducting experiments in three different universities on total of 138 pullout and 108 splitting specimens under monotonic loading. The key parameters examined in the experiments are low strength concrete, bar development length, concrete cover, rebar type (deformed, cold-formed, plain) and diameter. These deficient parameters are typically found in non-engineered reinforced concrete structures of developing countries. To develop ANN bond model for each bar type, four inputs (the low strength concrete, development length, concrete cover and bar diameter) are used for training the neurons in the network. Multi-Layer-Perceptron was trained according to a back-propagation algorithm. The ANN bond model for deformed bar consists of a single hidden layer and the 9 neurons. For Tor bar and plain bars the ANN models consist of 5 and 6 neurons and a single hidden layer, respectively. The developed ANN models are capable of predicting bond strength for both pull and splitting bond failure modes. The developed ANN models have higher coefficient of determination in training, validation and testing with good prediction and generalization capacity. The comparison of experimental bond strength values with the outcomes of ANN models showed good agreement. Moreover, the ANN model predictions by varying different parameters are also presented for all bar types.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.672-676
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• 2012

This paper studies the relation between the deformation of platen caused by clamping force, the bending stress and elongation at the tie-bar in injection molding machine of toggle type. These data are analyzed through analytical molding and numerical approach by tensile tester. The effect of bending stress on the stress concentration of teeth and nut system is also analyzed by 2 dimensional numerical approach. The bending stress of tie-bar caused by platen deformation becomes less than 20% of average tensile stress. And the effect of bending stress on stress concentration at teeth and nut system of tie-bar is found to be small.

• Journal of Biosystems Engineering
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• v.40 no.2
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• pp.110-114
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• 2015

Purpose: A threshing machine for shatter-resistant sesame was designed and developed in this study. Methods: Two types of sesame (shatter-resistant and conventional) were tested using the developed sesame threshing system. Three types of serrated bars were designed and evaluated through performance tests, in terms of the ratio of unthreshed sesame. Results: In the case of conventional sesame, the ratio of unthreshed sesame did not show any difference with bar type or cylinder rotation speed. For shatter-resistant sesame, however, the ratio of unthreshed sesame decreased with increased cylinder rotating speed for all three types of bar. Conclusions: These results are useful for the construction and utilization of an efficient threshing harvester. The type-L bar showed the best result in the energy equation.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.8
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• pp.877-882
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• 2005

This paper discusses the lateral vibration of a bar which has its tip free. The uniform bar has a solution by summation of some simple exponential functions But if its shape is not uniform, its solution could be by Bessel's function, or mathematical solution could not be existed. Enen if the solution of Bessel's function exists. as Bessel function is a series function. we must got the solution by numerical method Hereby the author Proposes the ununiform beam solution of the matrix method by Ritz's method. and Proposes a new deflection shape function.