• The Journal of Korean Society for Radiation Therapy
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• v.28 no.1
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• pp.57-64
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• 2016

Purpose : To evaluate the results of absorbed and effective doses using CBCT and 4D-CBCT settings for lung cancer. Materials and Methods : This experimental study. Measurements were performed using a Anderson rando phantom with OSLD(optically stimulated luminescent dosimeters). It was performed computed tomography(Lightspeed GE, USA) in order to express the major organs of the human body. Measurements were obtained a mean value is repeated three times each. Evaluations of effective dose and absorbed dose were performed the CL-IX-Thorax mode and Truebeam-Thorax mode CBCT. Additionally, compared Truebeam-Thorax mode CBCT with Truebeam-Thorax mode 4D-CBCT(Four-dimensional Cone Beam Computed Tomography) Results : Average absorbed dose in the CBCT of CL-IX was measured in lung 2.505cGy, heart 2.595cGy, liver 2.145cGy, stomach 1.934cGy, skin 2.233cGy, in case of Truebeam, It was measured lung 1.725cGy, heart 2.034cGy, liver 1.616cGy, stomach 1.470cGy, skin 1.445cGy. In case of 4D-CBCT, It was measured lung 3.849cGy, heart 4.578cGy, liver 3.497cGy, stomach 3.179cGy, skin 3.319cGy Average effective dose, considered tissue weighting and radiation weighting, in the CBCT of CL-IX was measured lung 2.164mSv, heart 2.241mSVv, liver 0.136mSv, stomach 1.668mSv, skin 0.009mSv, in case of Turebeam, it was measured lung 1.725mSv, heart 1.757mSv, liver 0.102mSv, stomach 1.270mSv, skin 0.005mSv, In case of 4D-CBCT, It was measured lung 3.326mSv, heart 3.952mSv, liver 0.223mSv, stomach 2.747mSv, skin 0.013mSv Conclusion : As a result, absorbed dose and effective Dose in the CL-IX than Truebeam was higher about 1.3 times and in the 4D-CBCT Truebeam than CBCT of Truebeam was higher about 2.2times However, a large movement of the patient and respiratory gated radiotherapy may be more accurate treatment in 4D-CBCT. Therefore, it will be appropriate to selectively used.

• Progress in Medical Physics
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• v.27 no.4
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• pp.196-202
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• 2016

We aim to develop the breast bolus by using a 3D printer to minimize the air-gap, and compare it to commercial bolus used for patients undergoing reconstruction in breast cancer. The bolus-shaped region of interests (ROIs) were contoured at the surface of the intensity-modulated radiation therapy (IMRT) thorax phantom with 5 mm thickness, after which the digital imaging and communications in mdicine (DICOM)-RT structure file was acquired. The intensity-modulated radiation therapy (Tomo-IMRT) and direct mode (Tomo-Direct) using the Tomotherapy were established. The 13 point doses were measured by optically stimulated luminescence (OSLD) dosimetry. The measurement data was analyzed to quantitatively evaluate the applicability of 3D bolus. The percentage change of mean measured dose between the commercial bolus and 3D-bolus was 2.3% and 0.7% for the Tomo-direct and Tomo-IMRT, respectively. For air-gap, range of the commercial bolus was from 0.8 cm to 1.5 cm at the periphery of the right breast. In contrast, the 3D-bolus have occurred the air-gap (i.e., 0 cm). The 3D-bolus for radiation therapy reduces the air-gap on irregular body surface that believed to help in accurate and precise radiation therapy due to better property of adhesion.

• Journal of radiological science and technology
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• v.47 no.4
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• pp.287-294
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• 2024

Radiation oncology departments are at high risk for potential radiation safety incidents. This study aimed to identify risk factors for these incidents using the P-mSHEL (Patient, Management, Software, Hardware, Environment, and Liveware) model and to evaluate potential accident types through Failure Mode and Effects Analysis (FMEA). FMEA identified seven accident types with high Risk Priority Number (RPN). A total of 56 detailed risk factors were classified using the P-mSHEL model, and measures to prevent radiation safety incidents were implemented. The effect of these preventive measures on workers' safety perception was confirmed through two indicators (FMEA and safety perception). After implementing the preventive measures, the FMEA analysis showed that the highest reduction in RPN was for A-6 (radiation exposure while other patients/guardians are present) with a reduction rate of 33.3%, followed by B-3 (radiation exposure while staff are present) with a reduction rate of 33.3%. Overall safety perception significantly improved after the preventive measures (4.17±0.35) compared to before (2.76±0.33) (p<0.05), with notable increases in both employee safety culture (3.93±0.51) and patient safety culture (3.73±0.62) (p<0.05). This study identified risk factors in radiation oncology departments. Continuous management, maintenance, and fostering a strong safety culture are crucial for preventing incidents. Regular problem identification and collaboration with relevant departments are essential for maintaining safety standards.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1850-1851
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• 1998

Using the "MAGIC" code, computer simulation is performed to design a cathode structure which provides a radial distribution of electron beam density matching the field distribution of the $TM_{05}$ mode. Thus, very narrow band $TM_{05}$ mode microwave radiation can be generated in an open end waveguide. The simulation results show that the vircator can indeed be operated at the selected frequency 10.2GHz with a very narrow bandwidth(${\Delta}{\omega}/{\omega}$ < 1%).

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.6
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• pp.286-292
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• 2005

Terahertz wave is a kind of electromagnetic radiation whose frequency lies in 0.1THz $\~$10THz range. In this paper, generation and detection characteristics of terahertz (THz) radiation by photoconductive antenna (PCA) method has been described. Using modern integrated circuit techniques, micron-sized dipole antenna has been fabricated on a low-temperature grown GaAs (LT-GaAs) wafer. A mode-locked Ti:Sapphire femtosecond laser beam is guided and focused onto photoconductive antennas (emitter and detector) to generate and measure THz pulses. Ultra-wide band THz radiation with frequencies between 0.1 THz and 3 THz was observed. Terahertz field amplitude variation with antenna bias voltage, pump laser power, pump laser wavelength and probe laser power was investigated. As a primary application example. a live clover leaf was imaged with the terahertz radiation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.10
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• pp.3344-3354
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• 1996

An experimental and numerical study on the three-dimensional natural convection-radiation conjugate heat transfer in the enclosure with heat generating chip has been performed. A 3-dimensional simulation model is developed by considering heat transfer phenomena by conduction-convection and radiation. Radiative transfer was analyzed with the discrete ordinates method. Experiments are conducted in order to validate the numerical model. Comparisons with the experimental data show that good agreement is obtained when the radiation effect is considered. The effects of the thermal conductivity of the substrate and power level on heat transfer are investigated. It is shown that radiation is the dominant heat transfer mode and the conductivity of the substrate has important effects on the heat transfer in the enclosure.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.2
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• pp.146-150
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• 2017

In OFDM system, the out-of-band radiation of ensemble interferes with the adjacent ensemble and result in the reduction of receiving performance. So the reduction scheme of out-of-band radiation is very important. In this paper, a time-domain windowing method to reduce the out-of-band radiation is considered to DAB systems. We adopt the considered method to T-DMB(DAB mode-1) and AT-DMB Systems, and we get about 3-dB gains of out-of-band radiation. And also we show that the considered method doesn't reduce the BER performance.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.419-422
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• 2007

This paper, designed UWB elliptical slot antenna and analysis based on the distribution of the electromagnetic fields pattern and resonant mode of designed antenna is presented. Designed antenna is fabricated on FR4 substrate with thickness of 1.524mm and relative dielectric constant 4.4. The measured bandwidth of $3.6GHz{\sim}20GHz$ for VSWR<2. Through the field pattern and resonant mode analysis that the slot antenna operates on a series of the multi-pole radiation based on TE modes matched to system impedance. And the perfect magnetic wall is along the axis of symmetry on the y-z plane. This result gives us an easier method to design the similar antennas, which is the impedance matching to the system impedance after once constructing a proper structure with a series of multi-mode resonances.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.487-491
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• 2003

Design procedure of corrugated horn antenna for mm-wave frequency range is presented, and hybrid condition in horn is calculated. Balanced hybrid mode should be converted in the horn from TE11 mode by the proper corrugation dimensions which size are available to be fabricated under the mm-wave short wavelength condition. In this paper, corrugate profiles which satisfy both hybrid condition and fabrication possibility are obtained.. By cylindrical mode theory, the electromagnetic fields both inside hem and corrugation are delivered. Propagation characteristics in hem is calculated by the mode impedance matching method with boundary conditions, and radiation fields are obtained by the Kirchhoff-Hyugen principle to the hem aperture fields. A mm-wave corrugated horn operates on 85 - 115GHz is designed and fabricated, and results of measurement are also shown.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.6
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• pp.46-52
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• 1985

A theoretical study of mutual coupling effects between two H-plane coupled microstrip patch antennas is presented. The radiation resistance and slot capacitance of a single micro-strip patch are calculated. To investigate the mutual coupling effects, the even and odd mode characteristic impedance and effective dielectric constants are obtained using the coupled microstrip line model. The S-parameter matrix elements 511,512 are used to study the mutual coupling e(facts in S-band frequency ranges for various patch spacings. Theoretical results and measurements are in good agreement.