• Journal of Sensor Science and Technology
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• v.5 no.3
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• pp.87-92
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• 1996

The PLT thin films on (100) cleaved MgO single crystal substrate have been fabricated by rf magnetron sputtering using a PbO-rich target. The dependence of physical and electrical properties on the degree of c-axis orientation has been studied. The degree of c-axis orientation of PLT thin films depends on fabrication conditions. Fabrication conditions of the PLT thin films were such that substrate temperature, working pressure, gas ratio of $Ar/O_{2}$, and rf power density were $640^{\circ}C$, 10 mTorr, 10 seem, and $1.7\;W/cm^{2}$, respectively. In these conditions, the PLT thin film showed the Pb/Ti ratio of 1/2 at the surface, the resistivity of $8{\times}10^{11}{\Omega}{\cdot}cm$, and dielectric constant of 110. The pyroelectric infrared sensors with these PLT thin films showed the peak to peak voltage of 450 m V and signal to noise ratio of 7.2.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.69-69
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• 2000

(Ba, Sr)TiO3 (BST)[1-3] 박막은 유전상수가 크고 고주파에서도 유전특성 저하가 적기 때문에 ULSI DRAM(Dynamic Random Access Memory)에 응용 가능한 물질로 최근 각광을 받고 있다. 하지만, 아직 BST 박막을 DRSM에 바로 적용하기 위해선 몇 가지 문제점이 있다. 그 중 누설전류 문제는 디바이스 응용시 매우 중요한 요소이다. 특히, DRAM에서 refresh time와 직접적인 관련이 있어 디바이스 내의 신뢰도 및 전력소모를 결정하는 주된 인자가 된다. 지금까지, BST 박막의 인가전업, 온도, 그리고 전극물질에 따른 누설전류 현상들이 고찰되었고, 이에 관한 많은 전도기구 모델들이 제시되었다. Schottky emission, Poole-Frenkel emission, space charge limited conduction 등이 그 대표적인 예이다. 하지만 아쉽게도 BST 박막의 정확한 누설 전류 전도 기구를 완전히 설명하는데는 아직 한계가 있다. 따라서 본 연구에서는 제작된 BST 커패시터 내의 기본적인 전기적 성질을 조사하고, 정확한 누설전류 기구 규명에 초점을 두고자 한다. 이를 위해 기존의 여러 기구들과 비교 분석할 것이다. 하부전극으로 사용하기 위해 스퍼터링 방법으로 p-Si(100) 기판위에 RuO2 박막을 약 120nm 증착하였다. 증착전의 chamberso의 초기압력은 5$\times$10-6 Torr이하의 압력으로 유지시켰다. Ar/O2의 비는 이전 실험에서 최적화된 9/1로 하였다. BST 박막 증착 시 5분간 pre-sputtering을 실시한 후 하부전극 기판위에 BST 박막을 증착하였다. 증착이 끝난 후 시편을 상온까지 냉각시킨 후 꺼내었다. 전기적 특성을 측정하기 상부전극으로 RuO2와 Al 박막을 각각 상온에서 100nm 증착하였다. 이때 hole mask를 이용하여 반경이 140um인 원형의 상부전극을 증착하였다. BST 박막의 증착온도가 증가하고 Ar/O2 비가 감소할수록 제작된 BST-커패시터의 전기적 성질이 우수하였다. 증착온도 $600^{\circ}C$, ASr/O2=5/5에서 증착된 막의 누설전류는 4.56$\times$10-8 A/cm2, 유전상수는 600 정도의 값을 나타내었다. 인가전압에 따른 BST 커패시터의 transition-current는 Curie-von Schweider 모델을 따랐다. BST 박막의 누설전류 전도기구는 기존의 Schottky 모델이 아니라 modified-Schottky 무델로 잘 설명되었다. Modified-Schottky 모델을 통해 BST 박막의 광학적 유전율 $\varepsilon$$\infty$=4.9, 이동도 $\mu$=0.019 cm2/V-s, 장벽 높이 $\psi$b=0.79 eV를 구하였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.1
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• pp.21-24
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• 2010

The effects of mole ratio(A/B) m and Ti-ion on the dielectric properties and microstructure of the microwave dielectric ceramics $(Ca_{0.7}Sr_{0.3})_m(Ti_yZr_{1-y})O_3$ were investigated. Ti ions substituted on Zr-sites in these modified $CaZrO_3$ composition strongly affect the sintering density and microstructure of the fired ceramic body. With increasing the amount of Ti substituted on Zr-sites, the sintered density rapidly increased and the dense microstructure was obtained for the compositions having mole ratio of 1.01, whereas the sintered density and microstructure are nearly constant with the content of Ti-ion for the compositions having mole ratio of 0.99. With increasing the content of Ti ion, the curve of TCC (Temperature Coefficient of Capacitance) as a function of temperature rotated clockwise and satisfied the COG characteristics for both of compositions with mole ratio of 0.99 and 1.01. The content of Ti ion seems to be more effective than mole with respect to the controlling of firing and TCC.

• Polymer(Korea)
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• v.33 no.1
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• pp.39-44
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• 2009

Polymer substrates were fabricated by using poly (phenylene ether) as a base resin, N,N'-m-phenylenedimaleimide (PDMI) as a crosslinking agent and decabromodiphenylethane as a flame retardant. The effects of crosslinking agent and flame retardant on physical properties such as dielectric property of the substrate were investigated. Thermal curing feature of PDMI with or without an initiator was analyzed by DSC, and then, PPE-PDMI test compositions were designed based on this result. Composite sheets were cast by film coater, laminated under vacuum and pressure, and then, the changes of dielectric constant, dielectric loss, peel strength, solder heat resistance and inflammability according to increasing amount of PDMI and flame retardant were evaluated, Dielectric constant and dielectric loss showed increasing trend with increasing amount of PDMI and flame retardant, but solder heat resistance and inflammability were improved. Peel strength was obtained higher than 1 kN/m when PDMI above 10 wt% was added, but slightly decreased as the amount of flame retardant increased. From the measured gel contents, the reaction mechanism of PPE-PDMI system was deduced to the formation of network structure by crosslinking PDMI with PPE rather than the formation of semi-IPN structure. In conclusion, the polymer composite substrate materials with dielectric constant of 2.52$\sim$2.65 and dielectric loss below 0.002 at 1 GHz were obtained and they will be proper for high frequency applications.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.11a
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• pp.159-163
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• 2002

So far, many kinds of researches on the chip components and MCM-C RF module especially on the 3-dimensional ceramic module using embedded passives have been performed. LTCC system has many kinds of advantages, like low loss, low cost of process, stability of process etc..The electrical behaviors of components are affected by that of the material systems including dielectrics and conductors. In this study, many kinds of conductor pastes in the variation with metal content and grain size are fabricated and their effect on the characteristics of stripline resonator are examined upto 6 ㎓.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.6 no.1
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• pp.45-50
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• 1981

Infrasonic transducer made with dielectric materials, such as polytetrafluoroethyleme(PTFE)film. The experimental result obtained that the response is within $\pm$1.5dB from 0.1Hz to 7KHz, and that sensitivities of typical transducer are fixed -60dB. The time constant of the transducer at room temperature is over 60 years, and the activation energy of the value of 1.1eV at 343K acquired. This transducer can have application to high-quality communication system, seismological observation etc.

• Journal of the Korean Ceramic Society
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• v.32 no.4
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• pp.448-454
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• 1995

The effect of WO3 addition on microwave dielectric properties of BaTiO3-3{(1-x)TiO2-xWO3} system was studied. Addition of WO3 to this system resulted in the formation of BaWO4 and Ba2Ti9O20 phases. Both the dielectric constant (K) and the temperature coefficientof resonant frequency (Tf) were decreased with the amount of WO3 addition. The value of Q$\times$f0 was increased as the amount of WO3 was increased up to x=0.0275, and then decreased when x exceeded 0.03. At x=0.0275, this ceramic showed excellent microwave proprties of K=34-35, Q$\times$f0=50,000-53,000, and near zero ppm/$^{\circ}C$ of Tf.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.6
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• pp.429-433
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• 2013

PTFE composites for use of microwave substrate were fabricated by impregnation and heat treatment fabrication with glass fabric. This study shows dielectric properties such as dielectric constant and loss can be controlled by thickness of PTFE composite with change of pressure condition in heating press process. The dielectric constant of the PTFE composites has decreasing tendency as given higher pressure condition. The dielectric loss has similar result too. Especially, the case of the dielectric loss was affected by the condition of pressure at heating press and had the best performance under 3 MPa. In order to see the reason why thickness conditions make different, their microstructures were also observed.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2031-2032
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• 2006

고압 배전선로를 전력선통신망으로 활용하기 위하여는 고압 배전선로에 대한 입력 임피던스에 대한 정확한 이론적 고찰과 실선로에서의 측정을 통한 검증이 요구된다. 본 논문에서는 고압 배전선로용 신호결합장치의 등가회로를 바탕으로 고압 전력선통신시스템의 입출력 모뎀을 제안한다. 제안된 시스템입출력 모델을 바탕으로 고압 배전선로의 고주파(2-30MHz) 대역의 입력 임피던스를 계산한다. 고압 배전선로 통신 입출력 모델에서 지면의 유전상수, 전력선의 길이, 지면의 도전율에 따른 배전선로 입력 임피던스의 이론적 분석과 실 선로에서의 입력 임피던스 측정 결과를 소개한다.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1309-1312
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• 1987

Hyperthermia for the treatment of cancer has been introduced for a long time and the biological effect for the use of hyperthermia to malignant tumors has been well established and encouraging clinical results has been observed. Unfortunately, the engineering or technical aspects of hyperthermia for the deep seated tumors has not been satisfactory. We have researched and developed the radiofrequency capacitive hyperthermia system (GHT- RF8). It was composed with 8-9 MHZ RF generator, capacitive electrode, matching system, cooling system, temperature measuring system and control computer. The thermal profile was investigated in agar phantom, animals and in human tumors, which was heated with capacitive RF device.