• The Journal of Korean Society for Radiation Therapy
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• v.8 no.1
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• pp.97-101
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• 1996

• The Journal of Korean Society for Radiation Therapy
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• v.9 no.1
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• pp.56-60
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• 1997

• Journal of Power Electronics
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• v.16 no.5
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• pp.1861-1868
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• 2016

In this paper, a three-phase AC-DC high step-up converter is developed for application to microscale wind-power generation systems. Such an AC-DC boost converter prossessess the property of the single-switch high step-up DC-DC structure. For power factor correction, the advanced half-stage converter is operated under the discontinuous conduction mode (DCM). Simulatanously, to achieve a high step-up voltage gain, the back half-stage functions in the continuous conduction mode (CCM). A high voltage gain can be obtained by use of an output-capacitor mass and a coupled inductor. Compared to the output voltage, the voltage stress is decreased on the switch. To lessen the conducting losses, a low rated voltage and small conductive resistance MOSFETs are adopted. In addition, the coupled inductor retrieves the leakage-inductor energy. The operation principle and steady-state behavior are analyzed, and a prototype hardware circuit is realized to verify the performance of the proposed converter.

• Journal of Power Electronics
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• v.15 no.2
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• pp.309-318
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• 2015

This study proposes a dual-output single-stage bridgeless single-ended primary-inductor converter (DOSSBS) that can completely remove the front-end full-bridge alternating current-direct current rectifier to accomplish power factor correction for universal line input. Without the need for bridge diodes, the proposed converter has the advantages of low component count and simple structure, and can thus significantly reduce power loss. DOSSBS has two uncommon output ports to provide different voltage levels to loads, instead of using two separate power factor correctors or multi-stage configurations in a single stage. Therefore, this proposed converter is cost-effective and compact. A magnetically coupled inductor is introduced in DOSSBS to replace two separate inductors to decrease volume and cost. Energy stored in the leakage inductance of the coupled inductor can be completely recycled. In each line cycle, the two active switches in DOSSBS are operated in either high-frequency pulse-width modulation pattern or low-frequency rectifying mode for switching loss reduction. A prototype for dealing with an $85-265V_{rms}$ universal line is designed, analyzed, and built. Practical measurements demonstrate the feasibility and functionality of the proposed converter.

• Journal of Power Electronics
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• v.14 no.5
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• pp.874-881
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• 2014

This study presents a single-phase power factor correction AC-DC converter that operates in discontinuous conduction mode. This converter uses the pulse-width modulation technique to achieve almost unity power factor and low total harmonic distortion of input current for universal input voltage $90V_{rms}$ to $264V_{rms}$) applications. The converter has a simple structure and electrical isolation. The magnetizing-inductor energy of the transformer can be recycled to the output without an additional third winding. The steady-state analysis of voltage gain and boundary operating conditions are discussed in detail. Finally, experimental results are shown to verify the performance of the proposed converter.

• Progress in Medical Physics
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• v.4 no.2
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• pp.19-25
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• 1993

Treatment planning of lung cancer with density corrected Computed tomography. Eighty-seven patients with lung cnacer who had radiation therapy in Yeungnam University Medical Center between, April 1 1990 and Aug. 30 1993 were retrospectively evaluated total tumor dose, dose distribution, field correction, and loading change, compared with contour or CT image planning and density corrected CT planning. In dose distribution, higher dose was calculated in compare with density corrected CT planning less than 5% difference were found in 45 patient(52%), 5-10% in 25 patients (29%), 10-15% in 15 patients (17%) and over 15% in 2 patients (2%). Correction of treatment field was performed in 18 patients (21%) and changing of dose loading was given in 15 patients (17%). In conclusion, we emphasize that density corrected CT planning is the very important factor which contribute to increase therapeutic gain by exact selection of target volume, target dose, normal tissue dose and dose of critical organ.

• The Journal of Korean Society for Radiation Therapy
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• v.24 no.1
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• pp.23-30
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• 2012

Purpose: There was a problem with using MU verification programs for the reasons that there were errors of MU when using MU verification programs based on Pencil Beam Convolution (PBC) Algorithm with radiation treatment plans around lung using Analytical Anisotropic Algorithm (AAA). On this study, we studied the methods that can verify the calculated treatment plans using AAA. Materials and Methods: Using Eclipse treatment planning system (Version 8.9, Varian, USA), for each 57 fields of 7 cases of Lung Stereotactic Body Radiation Therapy (SBRT), we have calculated using PBC and AAA with dose calculation algorithm. By developing MU of established plans, we compared and analyzed with MU of manual calculation programs. We have analyzed relationship between errors and 4 variables such as field size, lung path distance of radiation, Tumor path distance of radiation, effective depth that can affect on errors created from PBC algorithm and AAA using commonly used programs. Results: Errors of PBC algorithm have showned $0.2{\pm}1.0%$ and errors of AAA have showned $3.5{\pm}2.8%$. Moreover, as a result of analyzing 4 variables that can affect on errors, relationship in errors between lung path distance and MU, connection coefficient 0.648 (P=0.000) has been increased and we could calculate MU correction factor that is A.E=L.P 0.00903+0.02048 and as a result of replying for manual calculation program, errors of $3.5{\pm}2.8%$ before the application has been decreased within $0.4{\pm}2.0%$. Conclusion: On this study, we have learned that errors from manual calculation program have been increased as lung path distance of radiation increases and we could verified MU of AAA with a simple method that is called MU correction factor.

• Journal of Power Electronics
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• v.13 no.4
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• pp.592-599
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• 2013

This paper investigates a new isolated single-phase AC-DC converter, which integrates a modified AC-DC buck-boost converter with a DC-DC forward converter. The front semi-stage is operated in discontinuous conduction mode (DCM) to achieve an almost unity power factor and a low total harmonic distortion of the input current. The rear semi-stage is used for step-down voltage conversion and electrical isolation. The front semi-stage uses a coupled inductor with the same winding-turn in the primary and secondary sides, which is charged in series during the switch-on period and is discharged in parallel during the switch-off period. The discharging time can be shortened. In other words, the duty ratio can be extended. This semi-stage can be operated in a larger duty-ratio range than the conventional AC-DC buck-boost converter for DCM operation. Therefore, the proposed converter is suitable for universal input voltage (90~264 $V_{rms}$) and a wide output-power range. Moreover, the voltage stress on the DC-link capacitor is low. Finally, a prototype circuit is implemented to verify the performance of the proposed converter.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.sup3
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• pp.101-105
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• 2016

The number of deaths is often measured to monitor the population health status and priority of health problems. However, number of years of life lost (YLL) is a more appropriate indicator in some cases. We have calculated the YLL of adult cancers and its trend over the past few years in Yazd to provide planners with baseline data. Data obtained from death registration system were used to calculate the YLL, based on each individual's age at death, and the standardized expected YLL method was applied with a discount rate of 0.03, an age weight of 0.04, and a correction factor of 0.165. All data were analyzed and prepared in Epi6 and Excel 2007. A total of 3,850 death records were analyzed. Some 550 patients in Yazd province aged ${\geq}20$ die annually due to cancer (male: female ratio 1.3). The average ages at death in lung, CNS, breast cancer and leukemia cases were 68.5, 59, 58.7 and 61, respectively. The age group of 40-59 with 21 % had the highest cancer mortality percentage. Premature cancer deaths have caused 40,753 YLL (5,823 YLL annually). Females lose on average more life years to cancer than do men (11.6 vs 9.8 years). Lung cancer (12.1%), CNS tumors (11.7%) and leukemia (11.4 %) were the leading causes terms of YLL due to all cancers in both sexes. From 2004 to 2010, cancer-caused YLL as a fraction of all YLL increased from 12.8 to 15.2 %. This study can help in the assessment of health care needs and prioritization. Cancer is the major cause of deaths and the trend is increasing. The use of YLLs is a better index for measurement of premature mortality for ranking of diseases than is death counts. Longer periods of observation will make these trends more robust and will help to evaluate and develop, better public health interventions.

• Journal of Radiation Protection and Research
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• v.23 no.3
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• pp.139-147
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• 1998

Purpose: Tissue inhomogeneity such as lung affects tumor dose as well as transmission dose in new concept of on-line dosimetry which estimates tumor dose from transmission dose using the new algorithm. This study was carried out to confirm accuracy of correction by tissue density in tumor dose estimation utilizing transmission dose. Methods: Cork phantom (CP, density $0.202\;gm/cm^3$) having similar density with lung parenchyme and polystyrene phantom (PP, density $1.040\;gm/cm^3$) having similar density with soft tissue were used. Dose measurement was carried out under condition simulating human chest. On simulating AP-PA irradiation, PPs with 3 cm thickness were placed above and below CP, which had thickness of 5, 10, and 20 cm. On simulating lateral irradiation, 6 cm thickness of PP was placed between two 10 cm thickness CPs additional 3 cm thick PP was placed to both lateral sides. 4, 6, and 10 MV x-ray were used. Field size was in the range of $3{\times}3$ cm through $20{\times}20$ cm, and phantom-chamber distance (PCD) was 10 to 50 cm. Above result was compared with another sets of data with equivalent thickness of PP which was corrected by density. Result: When transmission dose of PP was compared with equivalent thickness of CP which was corrected with density, the average error was 0.18 (${\pm}0.27$) % for 4 MV, 0.10 (${\pm}0.43$) % for 6 MV, and 0.33 (${\pm}0.30$) % for 10 MV with CP having thickness of 5 cm. When CP was 10 cm thick, the error was 0.23 (${\pm}0.73$) %, 0.05 (${\pm}0.57$) %, and 0.04 (${\pm}0.40$) %, while for 20 cm, error was 0.55 (${\pm}0.36$) %, 0.34 (${\pm}0.27$) %, and 0.34 (${\pm}0.18$) % for corresponding energy. With lateral irradiation model, difference was 1.15 (${\pm}1.86$) %, 0.90 (${\pm}1.43$) %, and 0.86 (${\pm}1.01$) % for corresponding energy. Relatively large difference was found in case of PCD having value of 10 cm. Omitting PCD with 10 cm, the difference was reduced to 0.47 (${\pm}$1.17) %, 0.42 (${\pm}$0.96) %, and 0.55 (${\pm}$0.77) % for corresponding energy. Conclusion When tissue inhomogeneity such as lung is in tract of x-ray beam, tumor dose could be calculated from transmission dose after correction utilizing tissue density.