• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1125-1130
• /
• 2005

This paper presents a method for inter-sheet spacing control in a flexible media handling device. In order to verify the performance of inter-sheet spacing control by experiment, system of section structure is introduced in the first place. In the introduced system, each section is driven by different servo motor for independent section freedom. And suitable inter-sheet spacing control algorithm that is more optimal than conventional inter-sheet spacing control algorithm is proposed. Finally experiments are performed to confirm the performance of inter-sheet spacing control. And two inter-sheet spacing control algorithms, conventional and proposed, are compared with each other.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.31 no.3
• /
• pp.152-155
• /
• 2018

Ultrasonic wave technologies have been widely used in ultrasonic washing machines, ultrasonic surgery, ultrasonic welding machines, ultrasonic sensors, and medical instruments. Ultrasonic surgery can be realized through the cavitation effect of ultrasonic waves. In this study, piezoelectric ceramics were manufactured to achieve the optimum design of a piezoelectric vibrator in a handheld generator for ultrasonic surgery. The best specimen showed the excellent piezoelectric properties of kp＝0.624, Qm＝1,531, and $d_{33}=356pC/N$. Numerical modeling based on the finite element method was performed to find the resonance frequency, the anti-resonance frequency, and the displacement properties of the handheld ultrasonic generator. Maximum displacement was observed in the six-step piezoelectric vibrator at $6.36{\mu}m$.

• Computers and Concrete
• /
• v.16 no.1
• /
• pp.163-178
• /
• 2015

Due to the increase of the use of precast concrete structures in multistory buildings, this paper deals with the behavior of an specific type of beam-column connection used in this structural system. The connection is composed by concrete corbels, dowels and continuity bars passing through the column. The study was developed based on the experimental and numerical results. In the experimental analysis a full scale specimen was tested and for numerical study, a 3D computational model was created using a finite element analyze (FEA) software, called DIANA. The comparison of the results showed a satisfactory correlation between loading versus displacement curves.

• The Korean Journal of Ceramics
• /
• v.4 no.1
• /
• pp.20-24
• /
• 1998

Thin films of diamond-like carbon(DLC) can be successfully deposited by using a magnetron plasma chemical vapor deposition (CVD) method with an rf(13.56 MHz) plasma of $C_dH_8$. Plasma characteristics are analyzed as a function of the magnetic field. As the magnetic field increases, both electron temperature ($T_e$) and density ($n_e$)increase, but the negative dc self-bias voltage (-$V_{ab}$) decreases, irrespective of gas pressures in the range of 1~7 mTorr. High deposition rates have been obtained even at low gas pressures, which may be attributed to the increased mean free path of electrons in the magentron plasma. Effects of rf power and additive gas on the structural properties of DLC films aer also examined by using various technique namely, TED(transmissio electron diffraction) microanalysis, FTIR, and Raman spectroscopies.

• 한국전산유체공학회:학술대회논문집
• /
• 2010.05a
• /
• pp.501-504
• /
• 2010

In this study, fire behavior for subway coach fire in the 1/10 reduced scale model is analyzed using numerical analysis method (FDS). The size of the reduced model coach is 1.9 m long, 0.290 m high and 0.235 m. The simulation is carried out only one-sided four doors of the coach are opened. A fire source is the n-heptane pool fire with a mean heat release rate 2.33 kW. Smoke temperature, heat release rate and mass loss rate for the model are calculated.

• Journal of computational fluids engineering
• /
• v.11 no.4 s.35
• /
• pp.90-100
• /
• 2006

A digital wave tank (DWT) simulation technique has been developed by authors to investigate the interactions of fully nonlinear waves with 3D marine structures. A finite-difference/volume method and a modified marker-and-cell (MAC) algorithm have been used, which are based on the Navier-Stokes (NS) and continuity equations. The fully nonlinear kinematic free-surface condition is implemented by the marker-density function (MDF) technique or the Level-Set (LS) technique developed for one or two fluid layers. In this paper, some applications for various engineering problems with free-surface are introduced and discussed. It includes numerical simulation of marine environments by simulation equipments, fully nonlinear wave motions around offshore structures, nonlinear ship waves, ship motions in waves and marine flow simulation with free-surface. From the presented simulations, it seems that the developed DWT simulation technique can handle various engineering problems with free-surface and reliably predict hydrodynamic features due to the fully-nonlinear wave motions interacting with such marine structures.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.5 no.3
• /
• pp.31-39
• /
• 1996

The objective of this study is to investigate the influence of welding residual stresses on the fatigue crack growth behavior of cracks located transverse to the weld bead. For this purpose, G. T. A (Gas Tungsten Arc) welding was performed on hte Al alloy 1100-O plate and the same initial crack is made on HAZ(Heat Affected Zone), weld metal and base meta respectively. Specimens were used CT(Compact Tension) specimens. Initial welding residual stresses were measured by using strai gage sectioning method. All specimens were tested under constant amplitude load with stress ratio R=0.1, It is possible to predict fatigue crack growth behaviors and the fatigue life, using numerical analysis together with distribution of initial residual stress and the values of C and m obtained from $da/dN-{\Delta}K$

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1250-1254
• /
• 2008

In this study, A special quality analysis and experiment for low power consumption type pneumatic ISO Solenoid valve was performed. And flow characteristics of the ISO Solenoid valve by stroke change was numerically investigated. As a result, it is shown that magnetic force(2.4N) is exerted enough to move poppet with 0.3mm stroke with 0.01 seconds of response time, and that there is no magnetic force emitted by yoke.

• Journal of Power System Engineering
• /
• v.11 no.4
• /
• pp.56-64
• /
• 2007

A numerical simulation is carried out mixed convection in horizontal channel with a heat source from below of rectangular cavity. Finite volume method was employed for the discretization and PISO algorithm was used for calculating pressure term. The parameters governing the problem are the Reynolds number ($10^{-2}{\leq}Re{\leq}50$), the Rayleigh number ($10^3{\leq}Ra{\leq}2.06{\times}10^5$), the Prandtl number ($0.72{\leq}Pr{\leq}909$), the aspect ratio ($0.5{\leq}AR=W/H{\leq}2$) and the angle of inclination ($0^{\circ}{\theta}60^{\circ}$). Mean Nusselt number distributions were obtained and effect of Reynolds number, Rayleigh number and Prandtl number on mixed convection in the horizontal channel with rectangular cavity were investigated.

• 대한예방의학회:학술대회논문집
• /
• 1996.10a
• /
• pp.197-198
• /
• 1996