• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.584-588
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• 2001

A conventional power supply to drive a microwave oven has ferro-resonant transformer and high voltage Capacitor(HVC). Though it is simple, transformer is bulky, heavy and has low-efficiency. To improve this defect a high frequency inverter type power supply has been investigated and developed in recent years. But, because of additional control circuit and switching device, inverter-type power supply is more expensive than conventional one. In this study, A new pulse power supply for Microwave Oven using novel HVC embedded high frequency transformer is proposed for down-sizing, cost reduction, and efficiency emprovement of Inverter type power supply. Also, equivalent circuit model is derived by impedance measurements. And the operation of proposed pulse power supply is verified by simulations and experimental results.

• Korean Journal of Radiology
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• v.23 no.1
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• pp.42-51
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• 2022

Objective: This study aimed to investigate the direction of tissue contraction after microwave ablation in ex vivo bovine liver models. Materials and Methods: Ablation procedures were conducted in a total of 90 sites in ex vivo bovine liver models, including the surface (n = 60) and parenchyma (n = 30), to examine the direction of contraction of the tissue in the peripheral and central regions from the microwave antenna. Three commercially available 2.45-GHz microwave systems (Emprint, Neuwave, and Surblate) were used. For surface ablation, the lengths of two overlapped square markers were measured after 2.5- and 5-minutes ablations (n = 10 ablations for each system for each ablation time). For parenchyma ablation, seven predetermined distances between the markers were measured on the cutting plane after 5- and 10-minutes ablations (n = 5 ablations for each system for each ablation time). The contraction in the radial and longitudinal directions and the sphericity index (SI) of the ablation zones were compared between the three systems using analysis of variance. Results: In the surface ablation experiment, the mean longitudinal contraction ratio and SI from a 5-minutes ablation using the Emprint, Neuwave, and Surblate systems were 28.92% and 1.04, 20.10% and 0.53, and 24.90% and 0.45, respectively (p < 0.001). A positive correlation between longitudinal contraction and SI was noted, and a similar radial contraction was observed. In the parenchyma ablation experiment, the mean longitudinal contraction ratio and SI from a 10-minutes ablation using the three pieces of equipment were 38.60% and 1.06, 32.45% and 0.61, and 28.50% and 0.50, respectively (p < 0.001). There was a significant difference in the longitudinal contraction properties, whereas there was no significant difference in the radial contraction properties. Conclusion: The degree of longitudinal contraction showed significant differences depending on the microwave ablation equipment, which may affect the SI of the ablation zone.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2011.11a
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• pp.106-107
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• 2011

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.112-114
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• 1999

Superconducting multiplexer consisting of hairpin type filters has been designed for the reduction of the physical size of the device. Pulsed laser deposition with a Nd:YAG laser has been used to grow high quality YBCO superconducting films on MgO substrates. Multiplexer has been designed to have the center frequencies at 13.6 CHz and 13.9 GHz on MgO substrate with the size of 20 ${\times}$ 20 ${\times}$ 0.5mm$^3$. It is possible to implement superconducting multiplexer having two passbands on the limited 20 ${\times}$ 20 ${\times}$ 0.5mm$^3$ MgO substrate by adopting hairpin type filters. This type of superconducting device will be useful for the integration of microwave subsystem.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.7
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• pp.729-736
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• 2011

In this paper, we propose a varactor-diodeless voltage-controlled oscillator operating at X-band, and verify the possibility of applying to a receiver for microwave radar signal detection applications. The proposed VCO is realized by only single RF BJT device as a varactor diode is substitued by a intrinsic collector-base PN-junction of the active device which is used to generate negative resistance. The fabricated VCO meets the specification of the receiver, which has a 11.20~11.75 GHz tuning bandwidth with respect to the tuning voltage, 1.0~7.0 V, output power of 9.0~12.0 dBm and linear frequency tuning performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.597-602
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• 2008

This paper examines the damage effect and delay time of CMOS integrated circuits device with coupling caused by high power microwaves. The waveguide and magnetron was employed to study the influence of high power micro-waves on CMOS inverters. The CMOS inverters were composed of a LED circuit for visual discernment. Also CMOS inverters broken by high power microwave is observed with supply current and delay time. When the power supply current was increased 2.14 times for normal current at 9.9 kV/m, the CMOS inverter was broken by latch-up. Three different types of damage were observed by microscopic analysis: component, onchipwire, and bondwire destruction. Based on the results, CMOS inverters can be applied to database to elucidate the effects of microwaves on electronic equipment.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.442-448
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• 2022

Intermediate-level radioactive waste (ILW) is not subject to legal approval for cave disposal in Korea. To solve this problem, a spent resin treatment device that separates ¹⁴C-containing resin from zeolite/activated carbon and desorbs ¹⁴C through a microwave device has been developed. In this study, we evaluated the radiological safety of the operators performing repair work in the event of a failure in such a device treating 1 ton of spent resin mixture per day. Based on the safety evaluation results, it is possible to formulate a design plan that can ensure the safety of workers while developing a commercialized device. When each component of the resin treatment device can be repaired from the outside, the maximum and minimum allowable repair times are calculated as 263.2 h and 27.7 h for the ¹⁴C-detached resin storage tank and zeolite/activated carbon storage tank, respectively. For at least 6 h per quarter, the worker's annual dose limit remains within 50 mSv/year; further, over 5 years, it remained within 100 mSv. At least 6 h of repair time per quarter is considered, under conservative conditions, to verify the radiological safety of the worker during repair work within that time.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.188-188
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• 2012

Graphene, with its unique physical and structural properties, has recently become a proving ground for various physical phenomena, and is a promising candidate for a variety of electronic device and flexible display applications. Compared to indium tin oxide (ITO) electrodes, which have a typical sheet resistance of ${\sim}60{\Omega}$/sq and ~85% transmittance in the visible range, the chemical vapor deposition (CVD) synthesized graphene electrodes have a higher transmittance in the visible to IR region and are more robust under bending. Nevertheless, the lowest sheet resistance of the currently available CVD graphene electrodes is higher than that of ITO. In this study, we report a creative strategy, irradiation of microwave at room temperature under vacuum, for obtaining size-homogeneous gold nano-particle doping on graphene. The gold nano-particlization promoted by microwave irradiation was investigated by transmission electron microscopy, electron energy loss spectroscopy elemental mapping. These results clearly revealed that gold nanoparticle with ${\geq}30$ nm in mean size were decorated along the surface of the graphene after microwave irradiation. The fabrication high-performance transparent conducting film with optimized doping condition showed a sheet resistance of ${\geq}100{\Omega}$/sq. at ~90% transmittance. This approach advances the numerous applications of graphene films as transparent conducting electrodes.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.89-94
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• 2021

The mechanical reliability of flexible devices has become a major concern on their commercialization, where the importance of reliable bonding is highlighted. In terms of component materials' properties, it is important to consider thermal damage of polymer substrates that occupy large area of the flexible device. Therefore, room temperature bonding process is highly advantageous for implementing flexible device assemblies with mechanical reliability. Conventional epoxy resins for the bonding still require curing at high temperatures. Even after the curing procedure, the bonding joint loses flexibility and exhibits poor fatigue durability. To solve this problems, low-temperature and adhesive-free bonding are required. In this work, we develop a room temperature bonding process for polymer substrates using carbon nanotube heated by microwave irradiations. After depositing multiple-wall carbon nanotubes (MWNTs) on PET polymer substrates, they are heated locally with by microwave while the entire bonding specimen maintains room temperature and the heating induces mechanical entanglement of CNT-PET. The room temperature bonding was conducted for a PET/CNT/PET specimen at 600 watt of microwave power for 10 seconds. Thickness of the CNT bonding joint was very thin that it obtains flexibility as well. In order to evaluate the mechanical reliability of the joint specimen, we performed lap shear test, three-point bending test, and dynamic bending test, and confirmed excellent joint strength, flexibility, and bending durability from each test.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.205-205
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• 2015

최근, 비정질 산화물 반도체를 이용한 TFT는 투명성, 유연성, 저비용, 저온공정이 가능하기 때문에 차세대 flat-panel 디스플레이의 back-plane TFT로써 다양한 방면에서 연구되고 있다. 산화물 반도체 In-Zn-O-시스템에서는 Gallium (Ga)을 suppressor로 사용한 a-In-Ga-Zn-O (a-IGZO) 뿐만 아니라, Magnesium (Mg), Hafnium (Hf), Tin (Sn), Zirconium (Zr) 등의 다양한 물질이 연구되었다. 그 중 Silicon (Si)은 Ga, Hf, Sn, Zr, Mg과 같은 suppressor에 비해 구하기 쉬우며 가격적인 측면에서도 저렴하다는 장점이 있다. solution 공정으로 제작한 산화물 반도체 TFT는 진공 시스템을 사용한 공정보다 공정시간이 짧고, 저비용, 대면적화가 가능하다는 장점이 있다. 하지만, 투명하고 유연한 device를 제작하기 위해서는 저온 공정과 low thermal budget은 필수적이다. 이러한 측면에서 MWI (Microwave Irradiation)는 저온공정이 가능하며, 짧은 공정 시간에도 불구하고 IZO 시스템의 산화물 반도체의 전기적 특성 향상을 기대할 수 있는 효율 적인 열처리 방법이다. 본 연구에서는 In-Zn-O 시스템의 TFT에서 silicon (Si)를 Suppressor로 사용한 a-Si-In-Zn-O (SIZO) TFT를 제작하여 두 가지 열처리 방법을 사용하여 TFT의 전기적 특성을 확인하였다. 첫 번째 방법은 Box Furnace를 사용하여 N2 분위기에서 $600^{\circ}C$의 온도로 30분간 열처리 하였으며, 두 번째는 MWI를 사용하여 1800 W 출력 (약 $100^{\circ}C$)에 2분간 열처리 하였다. MWI 열처리는 Box Furnace 열처리에 비해 저온 공정 및 짧은 시간에도 불구하고 향상된 전기적 특성을 확인 할 수 있었다.