• Journal of Digital Convergence
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• v.11 no.8
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• pp.273-279
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• 2013

The purpose of the study was to present basic data to evaluation of the spatial resolution for exposure class(EC) in computed radiography(CR) by using the modulation transfer function(MTF). In this study, MTF was measured the edge method by using image plate(IP) of $100{\mu}mm$ pixels. A standard beam quality RQA5 based on an international electro-technical commission(IEC) standard was used to perform the X-ray imaging studies. Digital imaging began to set the sensitivity to EC 50, 100, 200, 300, 400, 600, 800, 1200 in X-ray irradiated to IP. The MTF 50% and 10% in the final images was analysis by using an authorized image analysis program the Origin 8.0 and the image J. As a results, the EC 200 was the best spatial resolution at MTF 50% ($1.979{\pm}0.114lp/mm$) and MTF 10% ($3.932{\pm}0.041$). Therefore, the EC 200 could be useful for the diagnosis of diseases that require high spatial resolution such as fractures.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.994-1000
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• 2004

We studied the characteristics of annular phase gratings as spatial frequency filters. We first calculated the Fraunhofer diffraction patterns of annular gratings and then got the modulation transfer function (MTF) from the zeroth order Hankel transform of the intensity distribution function. Binaryphase annular grating shows higher diffraction efficiency than binary phase rectangular grating. But the MTF decreases linearly in the low-frequency region as that of rectangular grating does. The diffraction pattern of 4-phase annular grating is similar to that of 2-phase grating and hence MTFs of the two are much alike. For 8-phase annular grating, the 7th order diffracted beam is the lowest one next to the first. Consequently, the diffraction efficiency is very high and the MTF graph is curved upward. The diffracted beams except the first order are negligible and hence the MTF characteristics are more improved in the case of 16-phase grating. But the degree of improvement becomes lowered c(Impaled with 8-phase grating. We made a 16-phase annular grating and measured its MTF. The experimental result agrees well with the calculated one.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.227-277
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• 2000

This paper presents an application of Mixed-Sensitivity H$_{\infty}$ control of a flexible manipulator. Firstly the detail model transfer function is derived from system identification. The objective is to position the free end of the beam with model including uncertainties and disturbance. we derive multiplicative uncertainties based on frequency response from difference between detail model and reduced model for designing controller. Finally we compare simulation results with experimental results.

• Laser Solutions
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• v.4 no.1
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• pp.21-28
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• 2001

Simulation on the electron beam welding of Al 2219 alloy was carried out by using commercial FEM code MARC, which encounters moving heat sources. Due to axisymmetry of geometry, a half of the cylinder was simulated. A coupled thermo-mechanical analysis was carried out and subroutine for heat flux was substituted in the program. The material properties such as specific heat, heat transfer coefficient and thermal expansion coefficient were given as a function of temperature and the latent heat associated with a given temperature range is considered. As a result, the proper beam power is 60㎸${\times}$60㎃ and welding speed is 1∼1.5 m/min. The residual stress in the heat-affected zone as well as the fusion zone does not increase. It is necessary to use jigs for preventing distortion of cylinder and improving weld quality.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2123-2125
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• 2002

This paper presents the use of piezoelectric ceramics for sensing and actuation purposes for vibration control. The PZT sensors and actuators are designed and fabricated. The transfer function of the beam is obtained via the Lagrangian method.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.3
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• pp.47-52
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• 2007

LMTT (Linear Motor based Transfer Technology), which is a new type transfer system used in the maritime container terminal for the port automation, is driven by PM LSM (Permanent Magnetic Linear Synchronous Motor), and largely consists of a controller, shuttle car, and rail. The shuttle car is divided into the frame part, the driving part, and wheels. Because the shuttle car is supported by four wheels in opposition to have five times length for the width of it, a larger deflection than other transfer system using the linear motor occurs. This deflection changes the gap between the mover and the stator, and then brings on an ununiform thrust force. So in this study, we dealt with the structural design for the mover of the shuttle car to generate the uniform thrust force for the efficient control of it. For the investigation, the thickness for each beam of the mover was adopted as design variables, the weight of the mover as objective function, and stress and deflection of the mover as constraint condition.

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.3
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• pp.176-185
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• 2023

Facebow transfer is essential for accurately mounting a dental cast onto a semi-adjustable articulator. The precision of traditional analog facebow transfer is influenced by both the accuracy of the equipment used and the skill level of the operator. Considering that substantial positional deviations can adversely affect the quality of a fabricated dental prosthesis; it is critical to assess the positional accuracy of casts mounted using analog facebow transfer. This case report evaluates the linear and angular deviations of the occlusal plane for maxillary casts mounted through both analog facebow transfer and cone-beam computed tomography-based methods. The findings indicate that analog facebow transfer produced a linear deviation ranging from 3 to 16 mm and an angular deviation of the occlusal plane between 5 to 7 degrees. This case report confirms that, across two patients, analog facebow transfer can result in varying degrees of positional deviation, thereby potentially leading to inaccuracies in the fabrication of dental prostheses. These results suggest that, in clinical practice, the use of analog facebow transfer may yield significant deviations during the process of mounting maxillary casts.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.132-136
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• 2005

It is widely accepted that the reading mechanism of Super-RENS(super-resolution near field structure) and Super-ROM(super-resolution read only memory) is closely related with non-linear temperature dependent material properties such as refractive indices, phase change. Furthermore, the dynamic change of the temperature distribution also an essential part of reading mechanism of Super-RENS/ROM. Therefore, the knowledge of the temperature distribution as a function a time is one of the important keys to reveal the physics of reading mechanism in Super-RENS/ROM. We calculated time-dependent temperature distribution in a 3-dimensional Super-ROM disk structure when moving laser beam is irradiated. With a help of commercial software FEMLAB which employed finite element method, we simulated the temperature distribution of ROM structure whose pit diameter is 120-nm with 50-nm depth. Energy absorption by moving laser irradiation, time variations of heat transfer processes, heat fluxes, heat transfer ratios, and temperature distributions of the complicate 3-dimensional ROM structure have been obtained.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.451-461
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• 2015

In megavoltage (MV) radiotherapy, delivering the dose to the target volume is important while protecting the surrounding normal tissue. The purpose of this study was to evaluate the modulation transfer function (MTF), the noise power spectrum (NPS), and the detective quantum efficiency (DQE) using an edge block in megavoltage X-ray imaging (MVI). We used an edge block, which consists of tungsten with dimensions of 19 (thickness) ${\times}$ 10 (length) ${\times}$ 1 (width) $cm^3$ and measured the pre-sampling MTF at 6 MV energy. Various radiation therapy (RT) devices such as TrueBeam$^{TM}$ (Varian), BEAMVIEW$^{PLUS}$ (Siemens), iViewGT (Elekta) and Clinac$^{(R)}$iX (Varian) were used. As for MTF results, TrueBeam$^{TM}$(Varian) flattening filter free(FFF) showed the highest values of $0.46mm^{-1}$ and $1.40mm^{-1}$ for MTF 0.5 and 0.1. In NPS, iViewGT (Elekta) showed the lowest noise distribution. In DQE, iViewGT (Elekta) showed the best efficiency at a peak DQE and $1mm^{-1}DQE$ of 0.0026 and 0.00014, respectively. This study could be used not only for traditional QA imaging but also for quantitative MTF, NPS, and DQE measurement for development of an electronic portal imaging device (EPID).

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.289-295
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• 2005

LMTT (Linear Motor-based Transfer Techn-ology) is a horizontal transfer system for the yard automation This system is based on PMLSM (Permanent Magnetic Linear Synchronous Motor) toot consists of stator modules on the rail and shuttle car. In this research, the kriging interpolation method with sequential sampling find the optimum design of mover in LMTT. The design variables are considered as the transverse, longitudinal and wheel beam's thicknesses. The objective function is set up as weight, while the constant function are set up as the stresses generated by four loading conditions. The objective function is set up as weight. The optimum results obtained by the suggested method are compared with those by the GENESIS.