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플라즈마 용사방식에 의해 형성된 탄화규소-페라이트 표면층의 마이크로파 흡수특성(I)
신동찬,손현,Shin, Dong-Chan,Son, Hyon 한국통신학회 1992 韓國通信學會論文誌 Vol.17 No.6
비행물체에 대한 레이다의 추적 및 탐색거리를 축소시키는 전자방어책의 일환으로 물리적, 기계적 특성이 우수한 전자파 흡수층을 제작하기 위해서 플라즈마 용사방삭을 이용하였다. 이 코팅층은 종래의 M/W흡수층 제작에 사용하던 도전재료인 탄소대신에 탄화규소를, 자성손실재료로는 Ni-Zn ferrite를, 그리고 보지재를 사용하는 대신에 이들 재료분말을 기계적으로 혼합하여 플라즈마 용사코팅으로 모재 표면에 직접 흡수층이 형성되도록 했다. X-band(8~13 GHz)레이다용 탄화규소-페리이트 전자파 흡수체를 실험적으로 설계하고 시험제작하여 전기적 특성을 평가한 결과, -6dB(M/W 에너지 흡수율 75%)의 반사량을 허용한도로 했을경우 약 7.6~8.4%의 대역폭이 얻어졌으며, 최대 흡수두께가 0.5~0.55mm로 매우 양호한 박층형 전자파 흡수체가 얻어졌다. Plasma-spraying was conducted to produced the microwave absorbing surface films on the alumi-num-alloy used for the fuselage to protect the aircraft against the RADAR detction. The surface films were produced by plasma-splaying the mecharucally mixed composite powders of the silicon carblde and Ni-Zn ferrite. This M /W absorbers were designed experimentally and fabricated trialty, as a result of which the rolative frequency bandwidth of 7.6 to 8.4% were obtained under the tolerance limits of the re-flection coefficients lower than -6dB(absorption ratio 75%), and the maximum absorption thickness becomes 0.5 to 0.5.imm, which Is much thinner than that of the conventional ones.
플라즈마 용사방식에 의해 형성된 페라이트-탄화규소 표면층의 마이크로파 흡수 특성(II)
신동찬,손현,Shin, Dong-Chan,Son, Hyon 한국통신학회 1993 韓國通信學會論文誌 Vol.18 No.8
레이다의 추적 및 탐색으로 부터 비행 물체를 보호하기 위한 목적으로, 알루미늄 합금표면에 페라이트-탄화규소 복합물인 마이크로파 흡수층을 플라즈마 용사방식으로 제작하였다. 본 논문에서는 페라이트-탄화규소층(I) 제조시 사용했던 탄화규소 입자의 평균크기인 34[rm]대신에15[rm]가 사용되었으며, 플라즈마 용사변수들 중에서 분말의 공급비율은 70[Kg/h]대신에 50[Kg/h] 그리고, 용사거리는 80[mm[ 대신에 100[mm]가 사용 되었다. X-band(8~12.4(GHz)레이다용 페라이트-탄화규소 전자파 흡수체를 실험적으로 설계하고 시험제작하여 전기적 특성을 평가한 결과, -lOdB의 반사량을 허용한도로 했을 때 약 2.8%의 대역폭이 얻어졌으며, 최대 흡수두께는 0.5(mm)로 매우 양호한 박층형 전자파 흡수체가 얻어졌다. Plasma spraying method was used to fabricated the microwave absorbing ferrite-silicon carbide on the aluminum-alloy of the fuselage of an aircraft to protect it from RADAR detection. In this paper 15[rm] instead of 34[rm], the mean size of SIC-powder for ferrite-silicon carbide surface films(I) was used. 50(Kg/h) Instead of 70(Kg/h), the powder feed and 100[mm] Instead of 80(mm), spray distance of spray parameters was used. This M/W absorbers were designed experimentally and fabricated trially, as a result of which the relative frequency bandwidth of 2.8% were obtained under the tolerance limits of the reflection coefficients lower than-10[dB], and the maximum absorption thickness becomes 0.5[mm], which is much thinner than that of the conventional ones.
암모늄 알루미늄 탄산염(hhCH)의 열분해에 의한 α-알루미나 나노분말 제조
오용택,신동찬,김상우,O, Yong-Taeg,Shin, Dong-Chan,Kim, Sang-Woo 한국세라믹학회 2006 한국세라믹학회지 Vol.43 No.4
[ ${\alpha}-Al_2O_3$ ] nanopowders were fabricated by the thermal decomposition and synthetic of Ammonium Aluminum Carbonate Hydroxide (AACH). Crystallite size of 5 to 8 nm were fabricated when reaction temperature of AACH was low, $8^{\circ}C$, and the highest $[NH_4{^+}][AlO(OH)_n{(SO_4){^-}}_{3-n/2}][HCO_3]$ ionic concentration to pH of the Ammonium Hydrogen Carbonate (AHC) aqueous solution was 10. The phase transformation fem $NH_4Al(SO_4)_2$, rhombohedral $(Al_2(SO_4)_3)$, amorphous-, ${\theta}-,\;{\alpha}-Al_2O_3$ was examined at each temperature according to the AACH. A Time-Temperature-Transformation (TTT) diagram for thermal decomposition in air was determined. Homogeneous, spherical nanopowders with a particle size of 70 nm were obtained by firing the 5 to 8 m crystallites, which had been synthesized from AACH at pH 10 and $8^{\circ}C,\;at\;1150^{\circ}C$ for 3 h in air.
열 CVD법으로 증착된 SnO<sub>2</sub> 박막의 미세구조와 전기적 특성
정진,최승평,신동찬,구재본,송호준,박진성,Jeong, Jin,Choi, Seong-Pyung,Shin, Dong-Chan,Koo, Jae-Bon,Song, Ho-Jun,Park, Jin-Seoung 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.5
When a SnO$_2$ thin film was deposited by thermal CVD, two different types of growth behavior that were dependent on the deposition temperature were observed. The film grown at 475$^{\circ}C$ had a wide grain size distribution and a faceted surface shape. On the other hand, the film grown at 5$25^{\circ}C$ had a relatively narrow grain size distribution and a rounded sulfate shape. The aspects of grain shape and growth behavior agree well with the theory of gram growth and a roughening transition. The charge tarrier density decreased with deposition time. According to photoluminescence measurements, the peak intensity of the spectra occurred at approximately 2.5 eV, which is related to oxygen vacancies, and decreased with increasing of deposition time. These measurement results suggest that the number of oxygen vacancies, which is related to the electrical conductivity, decrease with deposition time.
기판의 접촉각과 분말량이 자기조립을 통해 형성된 SiO<sub>2</sub> 광자결정의 광특성에 미치는 영향
오용택,김명순,신동찬,O, Yong-Taeg,Kim, Myung-Soon,Shin, Dong-Chan 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.7
This study investigated the effects of the substrate and powder content on the fabrication of SiO$_{2}$ photonic crystals by evaporation method. Photonic crystals were self-assembled on quartz, Corning 1737 glass, slide glass, and ITa glass to verify the effects of the wetting angle and surface morphology. The powder contents of the solution were varied from 0.2 to 2.0 wt$\%$. The number of photonic crystal layers increased according to the decrease of wetting angle and surface roughness. The resultant photonic crystals showed the best optical characteristics when the number of photonic crystal layers was within 40 and 50. In addition, the intensity peak of Fabry¡?Perot fringes increased when the wetting angle was large and the particle size was small. Photonic crystals coated on ITO glass showed the highest reflectance peak of 63$\%$ relative intensity.
자기조립을 통해 형성된 실리카 광자결정의 광특성에 미치는 열처리 효과
오용택,김명순,신동찬,O, Yong-Taeg,Kim, Myung-Soon,Shin, Dong-Chan 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.2
열처리가 단분산 구형 $SiO_2$ 나노 분말의 자기조립을 통하여 형성된 광자결정 박막의 광특성에 미치는 영향에 대하여 조사하였다. 광밴드갭에 의해 나타나는 반사율 피크는 열처리 온도가 증가함에 따라 단파장 쪽으로 이동하였고, 빛의 회절에 의해 나타나는 Fabry-Perot fringes 피크의 강도도 증가하였다. 또한, 반사율의 절대값도 $250\~300^{\circ}C$ 사이에서 열처리한 시편에서 가장 높은 값을 나타내었다. 미세구조 분석에 따르면 저온열처리를 통하여 입자크기와 결함량이 줄어들고 결정의 치밀도는 증가하였다. We examined the effect of low temperature heat-treatment on the optical properties of the photonic crystals self-assembled using a monodispersed spherical $SiO_2$ nanoparticle. When the heat treatment temperature increased, the reflectance peak, which is induced by the photonic band gap, moved to a shorter wavelength direction, and the peak intensity of Fabry-Perot fringes also increased. The highest reflectance peak intensity was obtained in the sample heat-treated at $250\~300^{\circ}C$. The heat-treatment reduced the average particle size and the quantity of defects, and increased the packing density of the photonic crystal.
PMW-PNN-PZT 세라믹스의 Bismuth 치환에 따른 미세구조 및 압전 특성
김용진,류주현,신동찬,Kim, Yong-Jin,Yoo, Ju-Hyun,Shin, Dong-Chan 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.6
In this study, in order to develop the composition ceramics for ultrasonic sensor with high $d_{33}*g_{33}$, $Pb_{1-3x/2}Bix(Mg_{1/2}W_{1/2})_{0.03}(Ni_{1/3}Nb_{2/3})_{0.09}(Zr_{0.5}Ti_{0.5})_{0.88}O_3$(PMW-PNN-PZT) system ceramics were prepared using CuO as sintering aids. And then, their microstructure, piezoelectric and dielectric characteristics were systemetically investigated with bismuth substitution. The PMW-PNN-PZT ceramic specimens could be sintered at sintering temperature of $940^{\circ}C$ by adding sintering aids. At x=0.015 specimen, the density, electromechanical coupling factor($k_p$), dielectric constant, piezoelectric constant($d_{33}$) and piezoelectric figure of merit($d_{33}*g_{33}$) indicated the optimal properties of $7.90g/cm^3$, 0.67, 2,511, 628 pC/N, and $17.7pm^2/N$, respectively, for duplex ultrasonic sensor application.
신상훈,류주현,신동찬,Shin, Sang-Hoon,Yoo, Ju-Hyun,Shin, Dong-Chan 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.12
In this study, in order to develop the capacitor composition ceramics with the good dielectric properties, $(Ba_{1-x}Ca_x)(Ti_{0.85}Zr_{0.12}Sn_{0.03})O_3$ (abbreviated as BCTZ) ceramics were prepared by the conventional solid-state reaction method. The effects of Ca substitution on the microstructure and dielectric properties was investigated. The X-ray diffraction patterns demonstrated that all the specimens showed perovskite phase, and secondary phases are indicated in the measurement range of X-ray diffraction. Also, all the specimens indicated an rhombohedron phase structure. It was identified from the X-ray diffraction patterns that the secondary phase formed in grain boundaries and then decreased the dielectric properties. For all the specimens, observed one peak was tetragonal cubic phase transition temperature($T_c$), which is located in the vicinity of room temperature.
[C<sub>12</sub>mim][TFSI] 용매 내에서 인가 전압이 Alq<sub>3</sub> 결정 성장에 미치는 영향
황선희 ( Sun Hee Hwang ),신동찬 ( Dong Chan Shin ) 조선대학교 공학기술연구원 2022 공학기술논문지 Vol.15 No.1
The effect of voltage on Alq<sub>3</sub> crystal growth in [C<sub>12</sub>mim][TFSI] was investigated. The additional voltage was applied through 1.0, 3.0, 5.0, 6.0, 8.0, 10.0 V. Cast iron and ITO were used as two electrodes. Microstructure analysis revealed the rod shape of Alq<sub>3</sub>. When the applied voltage increases, the population of rod shape phases increases. The XRD analysis showed that the initial phase transited to γ and finally δ phases. The conventional growth methods of the vapor phase and the solution method need a high temperature of over 300 ℃, while the study’s new approaches can lower the heat-treatment temperature to 100 ℃. The phase transition was promoted faster when the applied voltage increased from 0 to 10.0 V. The additional voltage is thought to play a vital role in promoting the phase transition due to lowering the activation energy of nucleation. The phase and shape of OLED materials affect the performance of the OLED device. One can obtain various shapes and phases of Alq3 at a low temperature of 100 ℃, which is a promising technique for OLED material manufacturing. The results also suggest a new academic point of view to understand the nucleation behavior of OLED materials with artificially applied charges.