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Hyunseok Lee(Hyunseok Lee),Dongryul Oh(Dongryul Oh),Yong Chan Ahn(Yong Chan Ahn),Hongryull Pyo(Hongryull Pyo),Kyungmi Yang(Kyungmi Yang),Jae Myoung Noh(Jae Myoung Noh) 대한방사선종양학회 2024 Radiation Oncology Journal Vol.42 No.1
Purpose: This retrospective study aimed to compare clinical outcomes and dosimetric parameters between radiation therapy (RT) techniques in patients with thymic epithelial tumor (TET). Materials and Methods: From January 2016 to December 2020, 101 patients with TET received adjuvant RT (median, 52.8 Gy; range, 48.4 to 66.0). Three different RT techniques were compared: three-dimensional conformal RT (3D-CRT; n = 59, 58.4%), intensity-modulated RT (IMRT; n = 23, 22.8%), and proton beam therapy (PBT; n = 19, 18.8%). Results: The median age of the patients and the follow-up period were 55 years (range, 28 to 79) and 43.4 months (range, 7.7 to 77.2). Patients in the PBT group were of the youngest age (mean age, 45.4 years), while those in IMRT group had the largest clinical target volume (mean volume, 149.6 mL). Patients in the PBT group had a lower mean lung dose (4.4 Gy vs. 7.6 Gy vs. 10.9 Gy, respectively; p < 0.001), lower mean heart dose (5.4 Gy vs. 10.0 Gy vs. 13.1 Gy, respectively; p = 0.003), and lower mean esophageal dose than patients in the 3D-CRT and IMRT groups (6.3 Gy vs. 9.8 Gy vs. 13.5 Gy, respectively; p = 0.011). Twenty patients (19.8%) showed disease recurrence, and seven patients (6.9%) died. The differences in the survival rates between RT groups were not statistically significant. Conclusion: In patients with TET who underwent adjuvant RT, PBT resulted in a lower dose of exposure to adjacent organs at risk. Survival outcomes for patients in PBT group were not significantly different from those in other groups.
A High Efficiency Boost Converter For TFT-LCD Bias Supply
Hyunseok Nam,Inseok Kim,Youngkook Ahn,Jeongjin Roh 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
In this paper, a high efficiency boost converter is designed using a 0.5-㎛ 5V, 3.5-㎛ 30-V CMOS process for TFT-LCD Bias supply. The boost converter can be adjusted with external resistors. The boost converter’s input power supply range is 2.5V ∼ 5V, the output voltage range is 10V-20V and the clock frequency is 1.3 ㎒. The maximum load current is 120㎃ at an input power supply of 3V, output voltage of 20V and the maximum efficiency is 92% with input power supply at 5V, output voltage of 12V, and load current of 120㎃. The simulation results show the successful operation of the boost converter.
Hyunseok Nam,Youngkook Ahn,Jeongjin Roh IEEE 2012 IEEE TRANSACTIONS ON POWER ELECTRONICS - Vol.27 No.1
<P>A high-voltage-tolerant buck converter with a novel adaptive power transistor driver is proposed in this paper. In order to minimize the <I>R</I><SUB>ON</SUB> of the cascode power transistor, the proposed scheme uses optimized and separated driving voltages for bias of the pMOS and nMOS power transistors. This increases not only the conversion efficiency, but also the maximum allowable load current for the transistor driver with small layout size, when compared to the buck converter with the earlier scheme. The measurements show that when the supply voltage is 2.5 V and the load current is 150 mA, the efficiency of the buck converter with the earlier scheme is 82%, whereas the efficiency of the buck converter with the proposed scheme is 92%, showing a maximum improvement of 10%. The designed buck converter uses the 0.35- μm-thick gate oxide CMOS process, and at 2.5-5 V of voltage, can supply up to 380 mA of load current. The total chip size is 2.7 mm<SUP>2</SUP>.</P>
An Inductor-type Current-Mode Buck Converter For Mobile Applications
Youngkook Ahn,Donghun Heo,Hyunseok Nam,Jeongjin Roh 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
An inductor-type current-mode DC-DC buck converter was evaluated through HSPICE simulation with 0.18㎛ CMOS process parameters. The current programmed mode (CPM) controller is designed for improved controllability of the DC-DC converter. A DC-DC buck converter is able to operate from 2.5V to 3.3V supply voltage. Overall peak efficiency is about 92%.
A 50-MHz Fully Integrated Low-Swing Buck Converter Using Packaging Inductors
Youngkook Ahn,Hyunseok Nam,Jeongjin Roh IEEE 2012 IEEE transactions on power electronics Vol.27 No.10
<P>Implementation of on-chip passive elements and efficient regulation schemes are key aspects of fully integrated dc-dc converter design. This paper presents a 50-MHz fully integrated buck converter equipped with packaging inductors. These inductors include parasitic inductances of the bonding wires and lead frames in the package. They have significantly better Q factors than the best on-chip inductors implemented on silicon. This paper also presents full-swing and low-swing gate drivers for efficient regulation of high-frequency switching converters. The low-swing driver uses the drop voltage of a diode-connected transistor and is applied in a fabricated converter to reduce the gate driving loss caused by the high switching operation. The proposed converter is designed and fabricated using a 0.13-μm 1-poly 6-metal CMOS process. The fully integrated buck converter achieves 68.7% and 76.8 % efficiency for 3.3 V/2.0 V and 2.5 V/1.8 V conversions, respectively, while providing a load current of 250 mA.</P>