• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.208-209
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• 2006

Sinterability and microwave dielectric properties of the $Zr1-x(Zn_{1/3}Nb_{2/3})xTiO_4$(x=4, 6) system ceramics have been investigated as functions of zinc-borosilicate(ZBS) glass contents and amount of $Zn_{1/3}Nb_{2/3}O_2$ substitution with a view to applying the composition to LTCC technology. The addition of 25 wt% ZBS glass ensured successful sintering below $925^{\circ}C$. With increasing ZBS glass and $Zn_{1/3}Nb_{2/3}O_2$ contents increased dielectric constant and sinterability but addition ZBS glass decreased the quality factor significantly due to the formation of an excessive liquid and second phases. The sintered $Zr4(Zn_{1/3}Nb_{2/3})6TiO_4$ system ceramics at $925^{\circ}C$ with 25 wt% ZBS glass demonstrated 27.7 in dielectric constant (${\varepsilon}_r$), 3,850 m quality factor($Q{\times}f_0$), and +6 ppm/$^{\circ}C$ in temperature coefficient of resonant frequency($\tau_f$).

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.19.2-19.2
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• 2010

Printed electronics using printing process has broadened in all respects such as electrics (lighting, batteries, solar cells etc) as well as electronics (OLED, LCD, E-paper, transistor etc). Copper is considered to be a promising alternative to silver for printed electronics, due to very high conductivity at a low price. However, Copper is easily oxidized, and its oxide is non-conductive. This is the highest hurdle for making copper inks, since the heat and humidity that occurs during ink making and printing simply accelerates the oxidation process. A variety of chemical treatments including organic capping agents and metallic coating have been used to slow this oxidation. We have established synthetic conditions of copper nanoparticles (CuNPs) which are resistant to oxidation and average diameter of 20 to 50nm. Specific resistivity should be less than $4\;{\mu}{\Omega}{\cdot}cm$ when sintered at lower temperature than $250^{\circ}C$ to be able to apply to conductive patterns of FPCBs using ink-jet printing. Through this study, the parameters to control average diameter of CuNPs were found to be the introduction of additive agent, the feeding rate of reducing agent, and reaction temperature. The CuNPs with various average diameters (58, 40, 26, 20nm) could be synthesized by controlling these parameters. The dispersed solution of CuNPs with an average size of 20 nm was made with nonpolar solvent containing 3 wt% of binder, and then coated onto glass substrate. After sintering the coated substrates at $250^{\circ}C$ for 30 minutes in nitrogen atmosphere, metallic copper film resulted in a specific resistivity of $4.2\;{\mu}{\Omega}{\cdot}cm$.

• 한국재료학회지
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• 제30권10호
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• pp.495-501
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• 2020

The various sintered samples comprising of 72 wt% (Al₂O₃) : 28 wt% (SiO₂) based ceramics were fabricated using a colloidal processing route. The phase analysis of the ceramics was performed using an X-ray diffractometer (XRD) at room temperature confirming the presence of Al₂O₅Si and Al_5.33Si_0.67O_9.33. The surface morphology of the fracture surface of the different sintered samples having different sizes of grain distribution. The resistive and capacitive properties of the three different sintered samples at frequency sweep (1 kHz to 1 MHz). The contribution of grain and the non-Debye relaxation process is seen for various sintered samples in the Nyquist plot. The ferroelectric loop of the various sintered sample shows a slim shape giving rise to low remnant polarization. The excitation performance of the sample at a constant electric signal has been examined utilizing a designed electrical circuit. The above result suggests that the prepared lead-free ceramic can act as a base for designing of dielectric capacitors or resonators.

• 한국산학기술학회논문지
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• 제11권1호
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• pp.228-233
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• 2010

Methyl hydrogen polysiloxne으로 처리한 ZnO, fumed $SiO_2$와 다양한 망간 전구체를 이용하여 서브마이크로미터 크기를 갖는 망간이 도핑된 $Zn_2SiO_4$ 형광체 입자를 고상법으로 제조하였다. 결정화와 광발광 특성은 XRD, SEM, PL스펙트라를 이용하여 분석하였다. 고상법으로 제조한 망간 도핑된 $Zn_2SiO_4$는 methyl hydrogen polysiloxne 처리한 ZnO의 분산과 응집 때문에 $1000^{\circ}C$에서 성공적으로 얻어졌고, 진공자외선 여기하에서 제조된 입자의 최대 PL강도는 0.02mol Mn, $1000^{\circ}C$에서 확인되었다.

• 한국분말재료학회지
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• 제22권6호
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• pp.396-402
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• 2015

The organic binder-free paste for dye-sensitized solar cell (DSSC) has been investigated using peroxo titanium complex. The crystal structure of $TiO_2$ nanoparticles, morphology of $TiO_2$ film and electrical properties are analyzed by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Electrochemical Impedance Spectra (EIS), and solar simulator. The synthesized $TiO_2$ nanopowders by the peroxo titanium complex at 150, 300, $400^{\circ}C$, and $450^{\circ}C$ have anatase phase and average crystal sizes are calculated to be 4.2, 13.7, 16.9, and 20.9 nm, respectively. The DSSC prepared by the peroxo titanium complex binder have higher $V_{oc}$ and lower $J_{sc}$ values than that of the organic binder. It can be attributed to improvement of sintering properties of $TCO/TiO_2$ and $TiO_2/TiO_2$ interface and to formation of agglomerate by the nanoparticles. As a result, we have investigated the organic binder-free paste and 3.178% conversion efficiency of the DSSC at $450^{\circ}C$.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
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• pp.214-219
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• 2009

In high-efficiency crystalline silicon solar cells, If high-efficiency solar cells are to be commercialized. It is need to develop superior contact formation method and material that can be inexpensive and simple without degradation of the solar cells ability. For reason of plated metallic contact is not only high metallic purity but also inexpensive manufacture. It is available to apply mass production. Especially, Nickel, Copper and Silver are applied widely in various electronic manufactures as easily formation is available by plating. The metallic contact system of silicon solar cell must have several properties, such as low contact resistance, easy application and good adhesion. Ni is shown to be a suitable barrier to Cu diffusion as well as desirable contact metal to silicon. Nickel monosilicide(NiSi) has been suggested as a suitable silicide due to its lower resistivity, lower sintering temperature and lower layer stress than $TiSi_2$. Copper and Silver can be plated by electro & light-induced plating method. Light-induced plating makes use the photovoltaic effect of solar cell to deposite the metal on the front contact. The cell is immersed into the electrolytic plating bath and irradiated at the front side by light source, which leads to a current density in the front side grid. Electroless plated Ni/ Electro&light-induced plated Cu/ Light-induced plated Ag contact solar cells result in an energy conversion efficiency of 14.68 % on $0.2{\sim}0.6{\Omega}{\cdot}cm,\;20{\times}20mm^2$, CZ(Czochralski) wafer.

• 한국세라믹학회지
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• 제53권2호
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• pp.215-221
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• 2016

In this study, the utilization of the by-products of various industries was examined using raw materials of CSA high-functional cement such as coal bottom ash, red mud, phosphate gypsum, etc. Technology to improve energy efficiency and reduce $CO_2$ was developed as part of the manufacturing process; this technology included lower temperature sintering ($150{\sim}200^{\circ}C$) than is used in the OPC cement manufacturing process, replacement of CSA cement with the main raw material bauxite, and a determination of the optimum mix condition. In order to develop CSA cement, a manufacturing system was established in the Danyang plant of the HANIL Cement Co. Ltd., in Korea. About 4,200 tons of low purity expansion agent CSA cement (about 16%) and about 850 tons of the lime-based expansion agent dead burned lime (about 8%) were produced at a rate of 60 tons per hour at the HANIL Cement rotary kiln. To improve the OPC cement properties, samples of 10%, 13%, and 16% of CSA cement were mixed with the OPC cement and the compressive strength and length variation rate of the green cement were examined. When green cement was mixed with each ratio of CSA cement and OPC cement, the compressive strength was improved by about 30% and the expansibility of the green cement was also improved. When green cement was mixed with 16% of CSA cement, the compressive strength was excellent compared with that of OPC cement. Therefore, this study indicates the possibility of a practical use of low-cost CSA cement employing industrial wastes only.

• 공업화학
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• 제5권1호
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• pp.44-53
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• 1994

고성능 니켈-철 축전지를 개발하기 위하여 알칼리 축전지로 이론적 용량밀도가 높고 저공해성, 저렴한 가격, 자원의 풍부성 등의 우수한 장점을 가지고 있는 철전극에 대한 연구를 수행하였다. 충방전반응의 특성을 전위주사법, SEM, XRD 분석으로 조사하였으며, 또한 전극용량을 정전류 충방전시험법으로 조사하였다. 철의 순도와 입자크기가 전극용량에 크게 영향을 미쳤으며, 첨가제 $Na_2S$는 전극의 부동태화를 방지하고 수소과전압을 높여 전극용량을 20% 정도 증대시켰다. 전극의 안정성과 용량은 Ni-fibrex와 foamed Ni집전체를 사용하여 증대시켰으며, 또한 소결온도에 영향을 받았다. 전극용량은 350 mAh/g(0.2 C)으로 나타났는데, 이는 이용률 36%에 해당한다.

• 한국세라믹학회지
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• 제40권3호
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• pp.273-278
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• 2003

다공질 세라믹스 흡음재료의 흡음특성과 물리.기계적 특성에 미치는 하수슬러지 슬래그 첨가량과 입경 효과에 대하여 조사하였다. 시편의 물리.기계적 특성은 슬래그 입경과 관계 없이 소성온도가 증가하고 슬래그 함량이 감소함에 따라 증가하였으며, 슬래그의 함량이 일정한 시편은 물유리 첨가량이 증가하고 슬래그 입경이 감소함에 따라 증가하였다. 1~3mm 크기의 슬래그를 약 77~89 wt% 함유하고 1,05$0^{\circ}C$에서 2시간 소성한 시편의 부피비중은 1.48~1.71, 압축강도 85~163 kgf/$\textrm{cm}^2$을 나타내었으며, 1~3mm의 슬래그를 이용한 시편은 저주파영역, 슬래그 입경이 1 mm이하인 시편은 고주파영역의 흡음특성이 향상되었으며, 시편의 두께가 증가함에 따라 저주파영역의 흡음특성이 향상되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.714-717
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• 2004

알루미노 보로실리케이트계 유리 기본조성 중 알칼리 토류 산화물의 종류 및 함량 변화에 따른 저유전율/저 LTCC 배선 기판의 저온 소성 거동 및 유전 특성을 조사하였다 알칼리 토류 산화물의 종류 및 함량 변화를 통해서 LTCC의 적정 소성온도인 $875^{\circ}C$ 부근을 포함하는 넓은 대역으로 소성수축이 시작되는 온도를 제어할 수 있었으며 유리 프리트와 알루미나 필러의 배합 비율의 변화에 따른 소성거동 및 유전특성의 변화 거동을 조사하였다. 알칼리 토류 산화물 중 유리 조성내의 CaO의 함량이 증가할수록 유리전이점 및 연화점을 증가하는 경향을 보였으며, 알루미나 필러의 첨가량이 증가할수록 소성수축이 시작되는 온도영역은 상향되고 유전율 및 품질계수는 증가하였다. 알칼리 토류 산화물의 조성과 필러인 알루미나의 함량을 제어함으로서 $875^{\circ}C$에서 18% 이상의 선수축율과 유전율 $5.1\sim5.5$ 및 유전손실 0.1% 이하의 우수한 특성을 갖는 저온소결용 LTCC 배선 기판을 얻을 수 있었다.