• Title/Summary/Keyword: RF Heating

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직류 전류 이용 종양세포의 효율적 치료에 관한 시뮬레이션 연구

  • Kim, Jae-Hong;Yang, Tae-Geon
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.289-289
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    • 2010
  • 정상 세포로부터 암과 같은 종양세포를 제거하는 방법으로 암세포가 사멸되는 임계온도 보다 높게 악성조직에 열을 가하는 방법이 연구되어지고 있다 [1]. 전류가 흐를 수 있는 4개의 전기탐침을 종양조직에 삽입하여 국부적으로 열을 발생시키는 발열요법으로 암을 치료하는 연구가 고려되고 있다. 발열요법은 1960년대에 시작하여 우리나라에서는 1985년 연세 암센터에서 capacitive type의 RF heating 또는 전자파에 의한 국소가온법과 방사선치료와 병용으로 이용되고 있다. 주로 이용되는 방법은 Radio frequency heating, Microwave heating, ultrasound heating을 들수 있다. 라디오주파수는 보통 300 MHz 이하의 주파수를 가리킨다. 본 연구에서는 교류파 대신에 직류전원에 의해 열을 발생하는 경우에 관한 연구이다. 전극에 의해 형성되는 전기장에 대한 방정식은 전도매질에서의 DC 응용모드이고, 조직 내에서의 직류 전류에 의해 발생되는 온도 분포를 모델링하는 bioheat 방정식과 연계된 문제이다. 전기장에 의해 발생되는 열의 근원은 resistive heat 또는 Joule 열이다. 본 연구에서는 교류 전류에 의한 RF heating 대신 단순한 모델의 경우로 직류 전류에 의한 열 발생에 관한 이론적 연구를 수행하였다. 종양 조직 내에 삽입된 전극에 22V를 인가하면 60초 이내에 $80^{\circ}C$까지 급속히 증가 된 후, 서서히 $90^{\circ}C$에 까지 도달한다. 4 개의 전극에 대칭적인 전위가 인가 된 경우 $50^{\circ}C$ 이상의 온도 분포를 암 조직의 모양과 유사하게 분포하게 하여 효과적인 치료를 수행 할 수 있는 조건을 제시한다.

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Role of Radio Frequency and Microwaves in Magnetic Fusion Plasma Research

  • Park, Hyeon K.
    • Journal of electromagnetic engineering and science
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    • v.17 no.4
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    • pp.169-177
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    • 2017
  • The role of electromagnetic (EM) waves in magnetic fusion plasma-ranging from radio frequency (RF) to microwaves-has been extremely important, and understanding of EM wave propagation and related technology in this field has significantly advanced magnetic fusion plasma research. Auxiliary heating and current drive systems, aided by various forms of high-power RF and microwave sources, have contributed to achieving the required steady-state operation of plasmas with high temperatures (i.e., up to approximately 10 keV; 1 eV=10000 K) that are suitable for future fusion reactors. Here, various resonance values and cut-off characteristics of wave propagation in plasmas with a nonuniform magnetic field are used to optimize the efficiency of heating and current drive systems. In diagnostic applications, passive emissions and active sources in this frequency range are used to measure plasma parameters and dynamics; in particular, measurements of electron cyclotron emissions (ECEs) provide profile information regarding electron temperature. Recent developments in state-of-the-art 2D microwave imaging systems that measure fluctuations in electron temperature and density are largely based on ECE. The scattering process, phase delays, reflection/diffraction, and the polarization of actively launched EM waves provide us with the physics of magnetohydrodynamic instabilities and transport physics.

A study on the growth of rutile single crystal by skull melting method (스컬법에 의한 루틸 단결정 성장에 관한 연구)

  • Seok Jeong-Won;Choi Jong-Koen
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.14 no.6
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    • pp.262-266
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    • 2004
  • Rutile single crystals were grown by the skull melting method. Ti metal ring was used for initial RF induction heating. The grown crystals were cut into wafer of 5.5 mm diameter and 1mm thickness. The wafers were annealed in air at $1300^{\circ}C$ up to 15 hours and their transmittance spectra $(\lambda= 200~25000 nm)$ were obtained.

RF Loss Minimization Method Using High Impedance Filter for Research (High Impedance Filter를 이용한 RF Loss 최소화 방법에 대한 연구)

  • Wang, Hyun-Chul;Seo, Hwa-Il
    • Journal of the Semiconductor & Display Technology
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    • v.19 no.1
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    • pp.55-60
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    • 2020
  • This study designed High impedance filter to reduce RF loss to heater heating wire and increase RF current flowing to heater ground wire. Effects such as D / R improvement and process reproducibility could be seen. In addition, RF parameter distribution optimization was possible by understanding the RF path of PE-CVD equipment using Plasma and designing filter.

Preparation of AlN thin films on silicon by reactive RF magnetron sputtering (RF 마그네트론 스퍼터링을 이용한 Si 기판상의 AlN 박막의 제조)

  • 조찬섭;김형표
    • Journal of the Semiconductor & Display Technology
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    • v.3 no.2
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    • pp.17-21
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    • 2004
  • Aluminum nitride(AlN) thin films were deposited on silicon substrate by reactive RF magnetron sputtering without substrate heating. We investigated the dependence of some properties for AlN thin film on sputtering conditions such as working pressure, $N_2$ concentration and RF power. XRD, Ellipsometer and AES has been measured to find out structural properties and preferred orientation of AlN thin films. Deposition rate of AlN thin film was increased with an increase of RF power and decreased with an increase of $N_2$ concentration. AES in-depth measurements showed that stoichiometry of Aluminium and Nitrogen elements were not affected by $N_2$ concentration. It has shown that low working pressure, low $N_2$ concentration and high RF power should be maintained to deposit AlN thin film with a high degree of (0002) preferred orientation.

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Continuous Photonic RF True-time Delay Using a Side-polished Fiber Bragg Grating with Heating Electrode (측면 연마된 광섬유 브래그 격자를 이용한 연속적인 광학적 RF 실시간 지연)

  • Chae, Ho-Dong;Kim, Do-Hwan;Kim, Hyoung-Jun;Lee, Sang-Shin;Kim, Hyo-Kyeom;Lee, Kyu-Hyo;Kim, Kwang-Taek
    • Korean Journal of Optics and Photonics
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    • v.15 no.6
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    • pp.591-596
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    • 2004
  • In this paper, a photonic RF true-time delay based on a partially side-polished fiber Bragg grating with heating electrode has been proposed and fabricated. It features continuous voltage-controlled operation, requiring no mechanical perturbation and no moving parts. For an RF signal carried over an optical signal, the time delay has been obtained by controlling the voltage applied to the electrode and thus adjusting its reflection positions from the fiber grating via the thermooptic effect. The achieved time delay is about 100 ps with the electrical power consumption of 280 mW.

Preparation of p-type transparent conducting $CuGaO_2$ thin film by DC/RF sputtering (DC-RF 스퍼터링에 의한 p형 투명 전도성 $CuGaO_2$ 박막의 제조)

  • Park, Hyun-Jun;Kwak, Chang-Gon;Kim, Sei-Ki;Ji, Mi-Jung;Lee, Mi-Jae;Choi, Byung-Hyun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.06a
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    • pp.48-48
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    • 2007
  • P-type transparent conducting $CuGaO_2$ thin films have been prepared by DC/RF sputtering using Quartz(0001) and sapphire(0001) substrates. The target was fabricated by heating a stoichiometric mixture of CuO and $Ga_2O_3$ at 1373K for 12h under $N_2$ atmosphere. The film were deposited under mixture gas of Ar and $O_2(Ar:O_2=4:1)$ during 10~30min. and the as-deposited films were annealed at 1123K and $N_2$ atmosphere. Room temperature conductivity and the activation energy of the sintered body in the temperature range of 223K ~ 423K were 0 004S/cm, 1.9eV, respectively. XRD revealed that all of the as-deposited films were amorphous. Heating of the films deposited on Quartz substrates above 1123K resulted in crystallization with a second phase of $CuSiO_3$, which was assumed owing to reaction with Quartz substrate. The single phase of $CuGaO_2$ was obtained at the film deposited on the sapphire substrates. The transmittance after annealing of DC- and RF-sputtered films were 55~75% at 550nm. From the transmittance and reflectance measurement. the direct band gap of the DC/RF-sputtered films were 3.63eV and 3.57eV. and there was little difference between DC and RF sputtered films.

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Development and Thermal Distribution of An RF Capacitive Heating Device (유전가열장치의 개발과 온열분포)

  • Chu, Sung-Sil;Suh, Chang-Ok;Kim, Gwi-Eon;Loh, John-Kyu;Kim, Byung-Soo
    • Radiation Oncology Journal
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    • v.5 no.1
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    • pp.49-58
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    • 1987
  • Hypertermia for the treatment of cancer has been introduced for a long time and the biological effect for the use of hyperthermia to treat malignant tumors has been well established and encouraging clinical results have been obserbed. Unfortunately, however, the engineering or technical aspects of hyperthermia for the deep seated tumors has not been satisfactory. We developed the radiofrequency capactive hyperthermia device (Greenytherm-GY8) in cooperation with Yonsei Cancer Center and Green Cross Medical Corporation. It was composed with $8{\sim}10MHz$ RF generator, capacitive electrode, matching system, cooling system, temperature measuring system and control PC computer. The thermal profile was investigated in agar phantom, animals and in human tumors, heated with capactivie RF device. Deep and homogeneous heating could be achieved in a large phantom of 25cm diameter and 19cm thick when heated with a pair of 23cm diameter electrodes, coupled to both bases of the phantom, when the size of the two electrodes was not the same, the region near the smaller electrode was preferentially heated. It was, therefore, possible to control the depth of heating by choosing proper size of electrodes. Therapeutic temperature $(42^{\circ}C{\sim}43^{\circ}C)$ could be obtained in the living animal experiments. Indications are that deep heating of humn tumors might be achieved with the capacitive method, provided that subcutaenous fat layer is cooled by temperature controlled bolus and large size of electrodes.

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A Characteristics of RF Sensitivity for a Firing Fuse (기폭용 퓨즈의 RF 감도 특성)

  • 간종만;권준혁
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.6
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    • pp.573-578
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    • 2004
  • EED consists of bridgewire, explosive charge, lead pins and metal case. If a firing signal is injected to EED, the explosive charge in EED is initiated by heating of bridgewire. Electromagnetic waves radiated from high power transmitters or radars can also cause unexpected firing of EED. Therefore, EMC design and test requirements for EED in military specifications are established and applied. This report describes the characteristics of RF sensitivity fur a firing fuse which is used fur EMC test instead of a real EED installed in aircraft. RF firing level of the fuse was predicted using transmission line(TL) theory. n sensitivity and RF sensitivity specified in military specifications were measured.

Power Absorption Measurements during NMR Experiments

  • Felix-Gonzalez, N.;Urbano-Bojorge, A.L.;de Pablo, C. Sanchez-L;Ferro-Llanos, V.;del Pozo-Guerrero, F.;Serrano-Olmedo, J.J.
    • Journal of Magnetics
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    • v.19 no.2
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    • pp.155-160
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    • 2014
  • The heating produced by the absorption of radiofrequency (RF) has been considered a secondary undesirable effect during MRI procedures. In this work, we have measured the power absorbed by distilled water, glycerol and egg-albumin during NMR and non-NMR experiments. The samples are dielectric and examples of different biological materials. The samples were irradiated using the same RF pulse sequence, whilst the magnetic field strength was the variable to be changed in the experiments. The measurements show a smooth increase of the thermal power as the magnetic field grows due to the magnetoresistive effect in the copper antenna, a coil around the probe, which is directly heating the sample. However, in the cases when the magnetic field was the adequate for the NMR to take place, some anomalies in the expected thermal powers were observed: the thermal power was higher in the cases of water and glycerol, and lower in the case of albumin. An ANOVA test demonstrated that the observed differences between the measured power and the expected power are significant.