• Journal of the Korean Society of Radiology
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• v.14 no.6
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• pp.811-817
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• 2020

This study aims to evaluate the Modulation Transfer Function (MTF) according to the change in the number of channels of the CT examination device by changing the posture of the patient to the X-axis and Y-axis in the wrist joint CT examination. Using a CT device and a wrist phantom, the test was performed by moving 0 (matched), 5, 10, and 15 cm in the X-axis around the isocenter, and the Z-axis was rotated by -20° and -40°. For the test, 16, -40 and 64 channels were used to check whether there was a difference for each number of channels. The examined images were compared by measuring the MTF values of the ulna and left and right sides of the radius. In the experiment where the isocenter was moved along the X-axis, the MTF value decreased with an increase in the moving distance, and the MTF value was found to be unaffected by the number of channels. In the experiment in which the wrist joint was rotated by -20° and -40° on the Z-axis, the degree of deviation and MTF were found to be irrelevant. It was not related to the number of channels either. In conclusion, the movement of the wrist along the X-axis should be restrained as much as possible for a wrist joint CT scan, whereas deviation around the Z-axis depending on the environment for the patient would not affect the MTF of the image.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.487-490
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• 2004

In order to simulate OLED evaporation process, modeling of directional distribution of the vaporized organic materials, film thickness distribution profile and pattern-mask shadow effect are required In accordance with many literatures; all of them except shadow effect modeling are studied and developed. In this paper, modeling algorithm of evaporation shadow is presented for process simulation of full-color OLED evaporating system. In OLED evaporating process the offset position of the point cell-source against the substrate rotation axis and the usage of the patterned mask are the principal causes for evaporation shadow. For geometric simulation of shadow using z-map, the film thickness profile, which is condensed on a glass substrate, is converted to the z-map data. In practical evaporation process, the glass substrate is rotated. This physical fact is solved and modeled mathematically for z-map simulation. After simulating the evaporation process, the z-map data can present the shadow-effected film thickness profile. Z-map is an efficient method in that the cross-sectional presentations of the film thickness profile and thickness distribution evaluation are easily and rapidly achieved.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.12
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• pp.78-84
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• 2009

When external force is applied to humanoid robot's head, humanoid robot's neck is rotated to prevent the damage of it. So, robot's neck have to perceive forces (Fx of x-direction, Fy of y-direction and Fz of z-direction) and moments (Mx of x-direction, My of y-direction and Mz of z-direction) using the attached 6-axis force/moment sensor. Thus, in this paper, 6-axis force/moment sensor was developed to sense the forces and moments applied to robot's head. The structure of 6-axis force/moment sensor was modeled newly, and it was designed using FEM software (ANSYS) and manufactured by attaching straingages on the sensing element, finally, the characteristic test of the sensor was carried out. As a result, it is confirmed that interference error is less than 3%. And, it is thought that the sensor can be used to measure the forces and the moments for humanoid robot's head.

• Journal of Radiation Protection and Research
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• v.33 no.2
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• pp.47-51
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• 2008

Objective: This study analyzed errors due to rotation or tilt of the magnetic resonance (MR) imaging indicator during image acquisition for a stereotactic radiosurgery. The error correction procedure of a commercially available stereotactic neurosurgery treatment planning program has been verified. Materials and Methods: Software virtual phantoms were built with stereotactic images generated by a commercial programming language, Interactive Data Language (version 5.5). The thickness of an image slice was 0.5 mm, pixel size was $0.5{\times}0.5mm$, field of view was 256 mm, and image resolution was $512{\times}512$. The images were generated under the DICOM 3.0 standard in order to be used with Leksell GammaPlan$^{(R)}$. For the verification of the rotation error correction function of Leksell GammaPlan$^{(R)}$, 45 measurement points were arranged in five axial planes. On each axial plane, there were nine measurement points along a square of length 100 mm. The center of the square was located on the z-axis and a measurement point was on the z-axis, too. Five axial planes were placed at z=-50.0, -30.0, 0.0, 30.0, 50.0 mm, respectively. The virtual phantom was rotated by $3^{\circ}$ around one of x, y, and z-axis. It was also rotated by $3^{\circ}$ around two axes of x, y, and z-axis, and rotated by $3^{\circ}$ along all three axes. The errors in the position of rotated measurement points were measured with Leksell GammaPlan$^{(R)}$ and the correction function was verified. Results: The image registration errors of the virtual phantom images was $0.1{\pm}0.1mm$ and it was within the requirement of stereotactic images. The maximum theoretical errors in position of measurement points were 2.6 mm for a rotation around one axis, 3.7 mm for a rotation around two axes, and 4.5 mm for a rotation around three axes. The measured errors in position was $0.1{\pm}0.1mm$ for a rotation around single axis, $0.2{\pm}0.2mm$ for double and triple axes. These small errors verified that the rotation error correction function of Leksell GammaPlan$^{(R)}$ is working fine. Conclusion: A virtual phantom was built to verify software functions of stereotactic neurosurgery treatment planning program. The error correction function of a commercial treatment planning program worked within nominal error range. The virtual phantom of this study can be applied in many other fields to verify various functions of treatment planning programs.

• Current Optics and Photonics
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• v.6 no.2
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• pp.183-190
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• 2022

Based on the linear electro-optic (EO) effect of lithium niobite (LiNbO₃, LN) crystal, an intense two-dimensional (2D) electric field sensor was analyzed, fabricated and experimentally demonstrated. The linear polarized light beam transmits along the optical axis (z-axis) of the LN crystal, and the polarization direction of the polarized light is 45° to the y-axis. The sensor can detect the intensity of a 2D electric field that is perpendicular to the z-axis. Experimental results demonstrated that the minimum detectable electric field of the sensor is 10.5 kV/m. The maximum detected electric field of the sensor is larger than 178.9 kV/m. The sensitivity of the sensor is 0.444 mV/(kV·m^-1). The variation of the sensitivity is within ±0.16 dB when the sensor is rotated around a z-axis from 0° to 360°. The variation of the sensor output optical power is within ±1.4 dB during temperature change from 19 ℃ to 26 ℃ in a day (from 7:00 AM to 23:00 PM) and temperature change from 0 ℃ to 40 ℃ in a controllable temperature chamber. All theoretical and experimental results revealed that the fabricated sensor provides technology for the direct detection of intense 2D electric fields.

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.142-148
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• 2004

We investigated a Ti:LiNbO$_3$ based integrated-optic polarization controller with a Ti-indiffused waveguide along the z-axis utilizing the electro-optic effect. The device consists of a first quarter-wave (λ/4) phase-shifter followed by a half-wave(λ/2) and a second quarter-wave(λ/4) wave-plate, which is rotated synchronously with the first quarter-wave phase-shifter. We analyzed the operation principles of the device utilizing cascaded transfer matrices based on Jones matrix and Poincare sphere, simulated driving voltages for various input states of polarization (SOP), and theoretically confirmed transformations from any arbitrary input SOP into any general output SOP.

• Journal of the Korean Data and Information Science Society
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• v.23 no.3
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• pp.495-504
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• 2012

In this study, we propose a statistical model based on projection that generates interview scores. In this model, each interviewee's true score and its related variable are viewed as X, Y values respectively in the two dimensional plane, and each interviewer's score is the projected score of true score X to the axis rotated by some angle, which reflects the interviewer's perspective. Each interviewer's observed interview score is obtained by adding personal bias and observed error to this projected score. We compared commonly used standardizing methods of interview scores such as trimmed mean method, rank method, and z-score method based on the proposed statistical model. In this simulation, two types of interview methods, two numbers of interviewers, two degrees of interviewers' expertise and two distributions and three correlations between actual score and its related variable are all considered.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.6
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• pp.1-15
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• 1974

In this paper, the SH mode of elastic surface waves which are used for delay lines of elastic surface wave is the cretically analysed. It is shown that the SH mode has very large electromechanical coupling factor and propagates on the surface with very small decaying coefficient into the medium. In the case of P2T-4, the depth cf piezoelectric medium that contains 80% of energy is 190 wavelengths. An elastic surface wave delay line is discussed from the view point of 2-port network. Center frequency is shifted by the ratio of transducer electrode width to gap between transducer ellcerodes when electromechanical coupling factor is large. Tempera _ore coefficients for bulk waves of LiNbO3 and LiTaO3 are also calculated and the minimum temperature coefficient value of delay time is 5.4X 10-6/$^{\circ}C$ ia the case of transverse wave propagating along Z axis on LiTaO3. Experimental data are in good agreement with theoretical values of the temperature coefficients of delay time for elastic surface waves propagating along X axis of 130$^{\circ}$ and 64$^{\circ}$ rotated Y cut planes of the LiNbO3.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.117-125
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• 2021

Purpose: To purpose of this study is to find the correlation of the Set-up error according to the couch rotation and suggest additional margin setting for the GTV. Target and Method: Each scenario treatment plan was created by making the frequency of non-coplanar beams different among all beams. The set-up error value was measured by using the Exact System and the dose accuracy was evaluated by creating a re-treatment plan. Results: When the couch was rotated by 30°, 45°, 60°, and 90°, the mean of the X-axis values was measured to be 0.29 mm, 0.26 mm, 0.51 mm, and 0.08 mm, respectively. The mean of the Y-axis values was measured to be 0.75 mm, 0.5mm, 0.35 mm, and 0.29 mm, respectively. The mean of the Z-axis values was measured to be 0.5 mm, 0.28 mm, 0.22 mm, and 0.1 mm, respectively. There were dose reductions of 0.1%, 3.1%, 1.9% in D99 for 1-NC VMAT, 2-NC VMAT, and 3-NC VMAT, respectively. Conclusion: When treating with 50% or more of non-coplanar beams among total beams, image verification is required. And it is considered to make the treatment plan by adding a 1.5 mm margin to the GTV.

• Journal of radiological science and technology
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• v.36 no.2
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• pp.123-129
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• 2013

This study investigated the rate of setup variance by the rotating unbalance of gantry in image-guided radiation therapy. The equipments used linear accelerator(Elekta Synergy TM, UK) and a three-dimensional volume imaging mode(3D Volume View) in cone beam computed tomography(CBCT) system. 2D images obtained by rotating $360^{\circ}$and $180^{\circ}$ were reconstructed to 3D image. Catpan503 phantom and homogeneous phantom were used to measure the setup errors. Ball-bearing phantom was used to check the rotation axis of the CBCT. The volume image from CBCT using Catphan503 phantom and homogeneous phantom were analyzed and compared to images from conventional CT in the six dimensional view(X, Y, Z, Roll, Pitch, and Yaw). The variance ratio of setup error were difference in X 0.6 mm, Y 0.5 mm Z 0.5 mm when the gantry rotated $360^{\circ}$ in orthogonal coordinate. whereas rotated $180^{\circ}$, the error measured 0.9 mm, 0.2 mm, 0.3 mm in X, Y, Z respectively. In the rotating coordinates, the more increased the rotating unbalance, the more raised average ratio of setup errors. The resolution of CBCT images showed 2 level of difference in the table recommended. CBCT had a good agreement compared to each recommended values which is the mechanical safety, geometry accuracy and image quality. The rotating unbalance of gentry vary hardly in orthogonal coordinate. However, in rotating coordinate of gantry exceeded the ${\pm}1^{\circ}$ of recommended value. Therefore, when we do sophisticated radiation therapy six dimensional correction is needed.