• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.229-229
• /
• 2013

저온작동형($500{\sim}700^{\circ}$) 고체산화물 연료전지의 전해질 재료의 응용이 기대되는 Gd doped ceria를 고주파 유도결합 열플라즈마 법으로 합성하고 그 특성을 조사하였다. 본 연구에서는 나노 ㄴCeO2 10~100 um의 CeO2와 1~20 um의 Gd2O3를 Ce：Gd이 9:1 mol%와 8:2 mol%의 비율로 혼합한 선구체를 140 kVA의 RF plate power와 O2/Ar 플라즈마 생성 가스 조건에서 형성된 고주파 유도결합 열 플라즈마에 주입하여 ~50 nm 이하의 입도와 fluorite 구조의 결정화된 CeO2 구조를 갖는 Gd doped ceria 나노 분말을 합성하였다. FE-SEM, TEM, XRD, ICP-OES, EDS, BET분석법을 이용하여, 합성된 분말의 입도, 미세구조, 결정 구조, 조성, 표면 등의 특성을 관찰하였다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2000.04b
• /
• pp.601-603
• /
• 2000

본 논문에서는 영상의 영역과 넓이를 이용하는 변형된 체인 코드에 기반한 복잡도와 영역 색상 정보를 이용한 내용 기반 영상 검색을 결합하여 WWW상에서 검색하는 시스템을 구현하였다. 입력된 영상을 이용하여 검색하는 방법을 사용하였으며, 색상 정보 추출은 RGB 신호를 256칼라로 양자화하였다. 보통의 정지 영상의 경우 대부분의 객체가 중앙에 있을 경우를 고려하여, 영상을 중앙 영역과 배경 영역으로 구분하고, 각각의 영역에서 두 개의 히스토그램을 생성한다. 중앙 영역과 배경 영역의 색상 히스토그램 인터섹션을 이용한 검색 및 물체의 복잡도를 결합한 방법도 제시하였다. 기존의 색상 히스토그램 인터섹션의 방법의 경우보다 물체의 복잡도를 결합한 제한된 방법이 실험결과에 더 좋은 결과를 얻을 수 있다.

• Journal of the Korean Ceramic Society
• /
• v.38 no.11
• /
• pp.1060-1066
• /
• 2001

Water-based alumina tapes for application of all-ceramic crowns were fabricated using PVP as binder that is biocompatible, highly soluble in solvents, and no residue leftafter firing. Tensile strength of alumina tapes was governed by binder/(binder+plasticizer)ratio. On the other hand, linear shrinkage and density were determined by alumina/(alumina+organic) ratio. Composite for all-ceramic crowns, prepared by infiltration of a glass into sintered porous alumina, showed high flexural strength which increased with increasing sintered density.

• Information and Communications Magazine
• /
• v.16 no.9
• /
• pp.28-41
• /
• 1999

위상배열 안테나 시스템에서 빔 제어 기술은 이동통신 및 위성통신시스템, 비행하고 있는 임의의 비행체의 위치를 고도의 정확도를 가지고 추적하는 군사용 레이더 시스템이나 항공사의 통신 시스템, 선박이나 차량간의 충돌을 방지하기 위한 충돌방지 시스템 등에서 널리 사용되고 있다. 이러한 위상배열 안테나 시스템에서 위상천이기를 이용하는 방법이 널리 사용되고 있다. 이 방법은 원리적으로 간단하지만 실제 구현할 때 위상천이기를 제어하기 위한 제어 신호와 DC 바이어스 라인들 그리고 전력분배기로 구성되어 있기 때문에 전체 회로가 복잡해진다. 뿐만 아니라 현재로서는 위상천이기의 가격과 삽입 손실 때문에 저렴하고 높은 이을 갖는 위상 배열 안테나 시스템을 구현하기가 힘들다. 본 논문에서는 위상천이기를 사용하지 않고 발진기들의 결합을 이용함으로써 이와 같은 단점을 극복하면서 배열 안테나의 복사 빔을 제어할 수 있는 결합발진기 배열 안테나의 최근 기술동향을 분석하고 여러 기술들의 장단점을 기술한다.

• Korean Journal of Optics and Photonics
• /
• v.18 no.3
• /
• pp.190-195
• /
• 2007

A novel optical coupling filter with finite-thickness metal-strip gratings printed on optical planar dielectric slabs is proposed, and Bragg conditions of the device are rigorously evaluated by using Modal Transmission-Line Theory (MTLT). The numerical results reveal that the guiding structures have filtering properties due to a leaky-wave stop-band while conventional DFB guiding structures consisted of dielectric gratings depend on a feedback-wave stop-band. Consequently, it shows that the optical coupling titter dependent on the leaky-wave filtering characteristics can be compounded of such optical devices as LD and optical fiber.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.1 no.1
• /
• pp.69-75
• /
• 1983

Among the gelatin hardness for photographic emulsion, the formal dehyde , dialdehydes, n-Methylol compounds, ketonea, carbonylic acid and carbamic acid derivatives, and s-Triazine derivatives were studied. The greater purts of hardeners formed cross-link by the reaction with ${\varepsilon}$-Amino group in the lysine and OH group in the hydroxylysine. Glutaraldehyde produced most stable cross-link due to the formation of pyridinum ion. 2.5 hexanedione and 3-hexone-2.5-dione possible to use as the ketone hardner . The sodium salt of 2.4-dichloro-6-hydroxy-S-Triazine was newly developed as the olefinic hardners for emulsion.lsion.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.10
• /
• pp.2059-2065
• /
• 2009

In this study, it has been considered that the TEM wave is incident on the transverse slit in the upper plate of a short-ended parallel-plate waveguide (PPW). An equivalent slit admittance and complex power for the case of narrow slit are obtained. The conditions for the slit voltage and the complex power in case of the maximum coupling through the slit with a nearby scatterer exterior the PPW are checked.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.2A
• /
• pp.213-219
• /
• 2007

In this paper, A novel structure of frequency doubler using Phase Delay line and $90^{\circ}$ Hybrid coupler at harmonic output have been designed and implemented to improve suppression. Proposed structure of frequency doubler improve output. coupling and fundamental suppression. Active frequency doubler with band from $2.13{\sim}2.15GHz\;to\;4.26{\sim}4.3GHz$ was designed and fabricated with 10dBm input power, 0.79dB conversion gain and -55.54dBc suppression at fundamental frequency, -44.76dBc suppression at third harmonic frequency 6.42GHz and -39.18dBc suppression at fourth harmonic frequency 8.56GHz.

• Journal of the Society of Naval Architects of Korea
• /
• v.35 no.2
• /
• pp.20-28
• /
• 1998

To accurately predict the motion of a submergible, the nonlinear structure of dynamic model should be selected and corresponding parameters should be estimated using model test. Providing the model structure, only the values of parameters are unknown and the estimation can thus be formulated as a standard least square problem. Unfortunately, the nonlinear model structure of submersibles is rarely known a prior and method of model structure determination from measurement data of model test should be developed and included as a vital part of the estimation procedure. In this study, the well-known linear least square algorithm for the analysis of model tests and a way to measure the goodness are reviewed, and the identification algorithm based on an orthogonal decomposition method of Gram-Schmidt is extended to combine structure selection and maneuvering coefficients estimation in a very simple and efficient manner. Finally, the efficiency of this algorithm is verified by using simulation and applying to the analysis of model test of a submerged body. As a result, it was verified that this combined method might be very erective in selecting the structure of dynamic model estimating the maneuvering coefficients from measurement fiat of model test.

• Journal of the Korean Ceramic Society
• /
• v.39 no.11
• /
• pp.1063-1068
• /
• 2002

Polyimide/silica(PI/silica) hybrid materials having physical or chemical bonds between the PI and silica network were prepared using sol-gel process through hydrolysis and polycondensation of tetraethoxysilane with the polyamic Acid(PAA) or end-capped PAA solution. PAA solution was synthesized by ring opening reaction of pyromellitic dianhydride and oxydianiline monomers in dimethyl acetamide solution. End-capped PAA solution was synthesized by the addition of 3-aminopropyltriethoxysilane in PAA solution. PI/silica hybrid samples were characterized by infrared spectroscopy, differential thermogravimetry, X-ray diffractometry, scanning electron microscopy, and tensile tester. It has been demonstrated that the properties of hybrid samples were affected by the silica content and the bond type between PI and silica.