• Title/Summary/Keyword: Microwave process

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Relationship between Structural Stability and Crystallinity in Layered Manganese Oxide (층상구조 망간산화물에서의 구조적 안정도와 결정성과의 관계)

  • Hwang, Seong-Ju
    • Journal of the Korean Chemical Society
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    • v.48 no.1
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    • pp.46-52
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    • 2004
  • The effect of crystallinity on the structural stability of layered manganese oxide has been systematically investigated. While well-crystalline manganate was prepared by solid-state reaction-ion exchange method, nanocrystalline one was obtained by Chimie-Douce reaction at room temperature. According to micro-Raman and Mn K-edge X-ray absorption spectroscopic results, manganese ions in both the manganese oxides are stabilized in the octahedral sites of the layered lattice consisting of edge-shared MnO6 octahedra. The differential potential plot clarifies that the layered structure of nanocrystalline material is well maintained during electrochemical cycling, in contrast to the well-crystalline homologue. From the micro-Raman results, it was found that delithiation-relithiation process for well-crystalline material gives rise to the structural transition from layered to spinel-type structure. On the basis of the present experimental findings, it can be concluded that nanocrystalline nature plays an important role in enhancing the structural stability of layered manganese oxides.

Manufacturing Conditions for Rice Porridge with Optimum Properties after Microwave Range Reheating (마이크로웨이브 레인지 재가열 후 최적 특성을 갖는 쌀죽 제조조건)

  • Park, Hye-Young;Kim, Hyun-Joo;Sim, Eun-Yeong;Kwak, Jieun;Chun, Areum;Jo, Youngje;Woo, Koan Sik;Kim, Mi Jung
    • The Korean Journal of Food And Nutrition
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    • v.33 no.4
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    • pp.440-446
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    • 2020
  • The purpose of this study was to derive the conditions for manufacturing rice porridge with optimum properties after reheating. The characteristics of rice porridge according to the soaking time, water addition rate, heating temperature, heating time, and cooling conditions were compared using the 'Samkwang' cultivar. In Step I, as the heating temperature increased, the weight change decreased and the viscosity increased, and the temperature known as the main factor of the gelatinization also appeared to affect the viscosity increase. In Step II, the viscosity and the texture properties was not significantly different as the soaking time was reduced, and 10 minutes was suitable because of due to the shortening effect of the total process time. In Step III, the residual heat was lowered by cooling after the rice porridge production, so the viscosity could be greatly reduced. Also, it was confirmed that the water addition rate of 900% and the heating temperature of 15 minutes were optimal manufacturing conditions. The next study will investigate the porridge processability of rice cultivars using these results.

Characteristics of SiGe Thin Film Resistors in SiGe ICs (SiGe 집적회로 내의 다결정 SiGe 박막 저항기의 특성 분석)

  • Lee, Sang-Heung;Lee, Seung-Yun;Park, Chan-Woo
    • Journal of the Korean Vacuum Society
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    • v.16 no.6
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    • pp.439-445
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    • 2007
  • SiGe integrated circuits are being used in the field of high-speed wire/wireless communications and microwave systems due to the RF/high-speed analog characteristics and the easiness in the fabrication. Reducing the resistance variation in SiGe thin film resistors results in enhancing the reliability of integrated circuits. In this paper, we investigate the causes that generate the resistance nonuniformity after the silicon-based thin film resistor was fabricated, and consider the counter plan against that. Because the Ti-B precipitate, which formed during the silicide process of the SiGe thin film resistor, gives rise to the nonuniformity of SiGe resistors, the boron ions should be implanted as many as possible. In addition, the resistance deviation increases as the size of the contact hole that interconnects the SiGe resistor and the metal line decreases. Therefore, the size of the contact hole must be enlarged in order to reduce the resistance deviation.

Variability Support in Component-based Product Lines using Component Code Generation (컴포넌트 코드 생성을 통한 컴포넌트 기반 제품 라인에서의 가변성 지원)

  • Choi, Seung-Hoon
    • Journal of Internet Computing and Services
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    • v.6 no.4
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    • pp.21-35
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    • 2005
  • Software product-lines is the software development paradigm to attain the rapid development of quality applications by customizing the reconfigurable components and composing them based on predefined software architectures. Recently various methodologies for the component-based product lines are proposed, but these don't provide the specific implementation techniques of the components in terms of variability resolution mechanism. In other hand, the several approaches to implement the component supporting the variabilities resolution are developed, but these don't define the systematic analysis and design method considering the variabilities from the initial phase. This paper proposes the integration of PLUS, the one of product line methodologies extending UML modeling, and component code generation technique in order to increase the efficiency of producing the specific product in the software product lines. In this paper, the component has the hierarchical architecture consisting of the implementation elements, and each implementation elements are implemented as XSLT scripts. The codes of the components are generated from the feature selection. Using the microwave oven product lines as case study, the development process for the reconfigurable components supporting the automatic variability resolution is described.

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The use of spectroscopic Ellipsometey for the observation of diamond thin film growth by microwave plasma chemical vapor deposition (마이크로웨이브 플리즈마 화학기상증착에 의한 다이아몬드 박막의 성장 관찰을 위한 분광 Ellipsometry의 이용)

  • 홍병유
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.8 no.2
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    • pp.240-248
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    • 1998
  • The plasma chemical vapor deposition is one of the most utilized techniques for the diamond growth. As the applications of diamond thin films prepared by plasma chemical vapor deposition(CVD) techniques become more demanding, improved fine-tuning and control of the process are required. The important parameters in diamond film deposition include the substrate temperature, $CH_4/H_2$ gas flow ratio, total, gas pressure, and gas excitation power. With the spectroscopic ellipsometry, the substrate temperature as well as the various parameters of the film can be determined without the physical contact and the destructiveness under the extreme environment associated with the diamond film deposition. It is introduced how the real-time spectroscopic ellipsometry is used and the data are analyzed with the view of getting the growth condition and the accompanied features for a good quality of diamond films. And it is determined the important parameters during the diamond film growth, which include the final sample will be measured with Raman spectroscopy to confirm the diamond component included in the film.

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Study on Synthesis and Electromagnetic Properties of Ni- Zn Ferrite Sintered at Low Temperature (저온 소결용 Ni-ZN계 페라이트의 합성 및 전자기적 특성 연구)

  • Kim, Chul-Won;Koh, Jae-Gui
    • Korean Journal of Materials Research
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    • v.12 no.8
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    • pp.600-607
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    • 2002
  • The Ni-Zn synthetic ferrite were acquired from thermally decomposing the metal nitrates Fe(NO$_3$)$_3$.$9H_2$O, Zn($NO_3$)$_2$.$6H_2$O, Ni($NO_3$)$_2$. $6H_2$O, and Cu($NO_3$)$_2$. $3H_2$O at $150^{\circ}C$ for 24 hours and was calcined at $500^{\circ}C$. Each of those was pulverized for 3, 6, 9, and 12 hours in a steel ball mill and was sintered between $700^{\circ}C$ and $1,000^{\circ}C$ for 1 hour, and then their microstructures and electromagnetic properties were examined. We could make the initial specimens chemically bonded in liquid at the temperature as low as $150^{\circ}C$, by using the melting points less than $200^{\circ}C$ of the metal nitrates instead of the mechanical ball milling, then narrowed a distance between the particles into a molecular level, and thus lowed sintering temperature by at least $200^{\circ}C$ to$ 300^{\circ}C$. Their initial permeability was 50 to 400 and their saturation magnetic induction density and coercive force 2,400 G and 0.3 Oe to 0.5 Oe each, which were similar to those of Ni- Zn ferrite synthesized in the conventional process. In the graph of initial permeability vs frequencies, we could observe a $180^{\circ}C$rotation of the magnetic domain, which appears in a broad band of microwave near the resonance frequency.

Regression Progress to Evaluate Metal Scale Thickness using Microwave (전파를 이용한 도체 Scale 분석에 Regression Progress 기법 이용 연구)

  • Muhn, Sung-Jin;Park, Wee-Sang
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.10 no.5
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    • pp.1-5
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    • 2010
  • This paper deals with a method to measure the thickness of scale-layer, iron oxide formed on the surface of the rolling steel, using a dielectric lens antenna. The dielectric lens antenna has an independent characteristic with the frequency in the X-band and changes the spherical wave radiated from a horn antenna into a plane wave at the focusing point. Using this concept, we regard a scale-layer on the rolling steel as a dielectric-PEC(Perfect Electric Conductor) layer and apply a theoretical analysis of the normal-incident plane wave. To reduce the phase error arising from the use of the dielectric lens antenna, this paper utilizes a regression process algorithm. In comparison with the conventional iteration algorithm, the present algorithm led to a unique solution for the thickness of the scale-layer.

Stacked LTCC Band-Pass Filter for IEEE 802.11a (IEEE 802.11a용 적층형 LTCC 대역통과 여파기)

  • Lee Yun-Bok;Kim Ho-Yong;Lee Hong-Min
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.2 s.93
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    • pp.154-160
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    • 2005
  • Microwave Otters are essential device in modem wireless systems. A compact dimension BPF(Band-pass Filter) for IEEE 802.11a WLAN service is realized using LTCC multi-layer process. To extrude 2-stage band-pass equivalent circuit, band-pass and J-inverter transform applied to Chebyshev low-pass prototype filter. Because parallel L-C resonator is complicate and hard to control the inductor characteristics in high frequency, the shorted $\lambda/4$ stripline is selected for the resonator structure. The passive element is located in the different layers connected by conventional via structure and isolated by inner GND. The dimension of fabricated stacked band-pass filter which is composed of six layers, is $2.51\times2.27\times1.02\;mm^3$. The measured filter characteristics show the insertion loss of -2.25 dB, half-power bandwidth of 220 MHz, attenuation at 5.7 GHz of -32.25 dB and group delay of 0.9 ns at 5.25 GHz.

Air-Bridge Interconnected Coplanar Waveguides Fabricated on Oxidized Porous Silicon(OPS) Substrate for MMIC Applications (산화된 다공질 실리콘 기판 위에 제작된 MMIC용 Air-Bridge Interconnected Coplanar Waveguides)

  • Sim, Jun-Hwan;Gwon, Jae-U;Park, Jeong-Yong;Lee, Dong-In;Kim, Jin-Yang;Lee, Hae-Yeong;Lee, Jong-Hyeon
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.39 no.4
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    • pp.19-25
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    • 2002
  • In this paper, to improve the characteristics of a transmission line on silicon substrate, we fabricated air-bridge interconnected CPW transmission line on a 10-${\mu}{\textrm}{m}$-thick oxidized porous silicon(OPS) substrate using surface micromachining. Air-bridge interconnected CPW of S-W-S = 30-80-30 ${\mu}{\textrm}{m}$has insertion loss of -0.25 ㏈ and return loss of -28.9 ㏈ at 4㎓ And return loss of CPW with stepped compensated air-bridge(S-W-S : 30-100-30 ${\mu}{\textrm}{m}$) is improved -0.98㏈ at 4㎓. The results indicate that the thick OPS provides an approach to incorporate high performance, low cost microwave and millimeter wave circuits in a high-resistivity silicon-based process.

Development of Large Signal Model Extractor and Small Signal Model Verification for GaAs FET Devices (GaAs FET소자 모델링을 위한 소신호 모델의 검증과 대신호 모델 추출기 개발)

  • 최형규;전계익;김병성;이종철;이병제;김종헌;김남영
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.12 no.5
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    • pp.787-794
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    • 2001
  • In this paper, the development of large-signal model extractor for GaAs FET device through the Monolithic Microwave integrated Circuit(MMIC) is presented. The measurement program controlled by personal computer is developed for the processing of an amount of measured data, and the de-embedding algorithm is added to the program for voltage dropping as attached series resistance on measurement system. The small-signal model parameters are typically consisted of 7 elements that are considered as complexity of large-signal model and its the accuracy of the small-signal model is verified through comparing with measured data as varied bias point. The fitting function model, one of the empirical model, is used for quick simulation. In the process of large-signal model parameter extraction, one-dimensional optimization method is proposed and optimized parameters are extracted. This study can reduce the modeling and measuring time and can secure a suitable model for circuit.

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