• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
• /
• pp.165-166
• /
• 2008

$(Ba_{0.6},Sr_{0.3},Ca_{0.1})TiO_3$ powders, which were prepared by sol-gel method using a solution of Ba-acetate, Sr-acetate and Ca-acetate and Ti iso-propoxide, were mixed with organic vehicle and the BSCT thick films were fabricated by the screen-printing techniques on high purity alumina substrates. The structural and dielectirc properties were investigated for various $Pr_2O_3$ and $Y_2O_3$doping contents. As a result of thermal analysis of $(Ba_{0.6},Sr_{0.3},Ca_{0.1})TiO_3$ powders, the exothermic peak was observed at around $670^{\circ}C$ due to the formation of the polycrystalline perovskite phase. All BSCT thick films, sintered at $1420^{\circ}C$ for 2h, showed the typical XRD patterns of perovskite polycrystalline structure. The average grain size of the specimens decreased with amount of $Pr_2O_3$ and $Y_2O_3$ contents.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
• /
• pp.167-167
• /
• 2008

The barium strontium calcium titanate powders were prepared by sol-gel method. Ferroelectric $(Ba_{0.54}Sr_{0.36}Ca_{0.1})TiO_3$(BSCT) thick films were fabricated by the screen-printing method on alumina substrate. And we investigated the structural and dielectric properties of BSCT thick films with the variation of sintering temperature. As a result of thermal analysis, BSCT polycrystalline perovskite phase was formed at around $660^{\circ}C$. The results of X-ray diffraction analysis were showed a cubic perovskite structure without presence of the second phase in all BSCT thick films. The average grain size and the thickness of the specimen sintered at $1450^{\circ}C$ were about 1.6 mm and 45 mm, respectively. The relative dielectric constant increased and the dielectric loss decreased with increasing the sintering temperature, the values of the BSCT thick films sintered at $1450^{\circ}C$ were 5641 and 0.4% at 1kHz, respectively.

• Nuclear Engineering and Technology
• /
• 제54권3호
• /
• pp.1024-1029
• /
• 2022

Composite scintillation screens on a base of Gd_1.2Y_1.8Ga_2.5Al_2.5O₁₂:Ce (GYAGG) scintillator have been evaluated for neutron detection. Besides the powdered scintillator, the composite includes ⁶LiF particles; both are merged with a binder and deposited onto the light-reflecting aluminum substrate. Results obtained demonstrates that screens are suitable for use with a silicon photomultiplier readout to create a prospective solution for a compact and low-cost thermal neutron sensor. Composite GYAGG/⁶LiF scintillation screen shows a pretty matched sensitivity and γ-background rejection with a widely used ZnS/⁶LiF screens however, possesses forty times faster response.

• 대한의용생체공학회:의공학회지
• /
• 제43권4호
• /
• pp.219-229
• /
• 2022

In this study, we propose a miniaturized micro-ceramic heater device. After screen-printing a silver paste between pre-sintered two aluminum oxide plates to integrate a heating circuit, the device was fabricated through a low-temperature sintering process. In order to configure the optimal heating circuit integration condition, the output current evaluation and heating test were performed according to the number of screen prints of the silver paste at various voltages. A silver paste-based heating circuit printed with a line width of 200 ㎛ and a thickness of 60 ㎛ was successfully integrated on a pre-sintered alumina substrate through a low-temperature sintering process. In the case of the 5 times printed device, the thermal response showed a response rate of 18.19 ℃/sec. To demonstrate feasibility of the proposed device in the medical field, such as bio-tissue suturing and hemostasis, a voltage was applied to pig tissue in the device to test tissue change due to heat generated from the device. These results show the possibility that the proposed small ceramic heater could be used in the medical field based on its excellent temperature response.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회B
• /
• pp.2124-2129
• /
• 2007

A VCHP was fabricated and tested for its thermal performance. The container was made of copper, and the working fluid was water. STS-316 screen of mesh number 100 was inserted as a capillary structure. As a baseline performance, a normal heat pipe of the same dimensions was tested in advance to compare with VCHP, where an inert gas container was attached. The outer diameter of the heat pipe was 12.8 mm and the total length was 600 mm. The evaporator and the condenser lengths were both 200 mm. The thermal load ranged from 20 to 300W. Typical result revealed that the operating temperature of the VCHP stayed almost constant, while that of the normal heat pipe varied as much as 40$^{\circ}C$. Therefore, it was demonstrated that the VCHP is very effective for temperature control of heat-dissipating devices.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
• /
• pp.1060-1062
• /
• 2002

Spherical and dense BAM phosphor particles were prepared by spray pyrolysis. The key idea of dense BAM particles is to lead gelation in droplets, which was successfully achieved by using the aluminum polycation as the precursor solution for the spray pyrolysis. The BAM phosphor particles prepared by spraying the aluminum polycation solution have completely spherical shape and dense structure. When directly applied to make phosphor film on the glass by the screen-printing method, the prepared spherical BAM phosphor particles showed better packing density and surface morphology than that of commercial one, which has irregular shape and large particle size. It was also found that the thermal degradation in the photoluminescence intensity for dense and spherical BAM particles was less than that of commercial one.

• 설비공학논문집
• /
• 제13권1호
• /
• pp.18-24
• /
• 2001

Woven wire wick is very effective structure because of its easiness to insert inside of pipe for a miniature heat pipe. The present study was conducted to investigate the effect of the effective flow passage with respect to wire helix angle. Also effective thermal conductivity were examined by defining mean porosity considering effective liquid flow passages. Effective heat transfer area is varied with respect to wire helix angle, and in the range of $\thet=60~65^{\circ}C$, heat transfer area is decreased about 15~20%. Permeability of woven wire wick shows similar value of 200 mesh screen wick. And comparison of experimental results on effective thermal conductivity shows a fairly good agreement with the analytical results.

• 한국전기전자재료학회논문지
• /
• 제25권3호
• /
• pp.236-240
• /
• 2012

Limiting thermal exposure time using rapid thermal processing(RTP) has emerged as promising simplified process for manufacturing of solar cell in a continuous way. This paper reports the simplification of co-firing using RTP. Actual temperature profile for co-firing after screen printing is a key issue for high-quality metal-semiconductor contact. The plateau time during the firing process were varied at $450^{\circ}C$ for 10~16 sec. Glass frit in Ag paste etch anti-reflection layer with plateau time. Glass frit in Ag paste is important for the Ag/Si contact formation and performances of crystalline Si solar cell. We achieved 17.14% efficiency with optimum conditions.

• 한국태양에너지학회 논문집
• /
• 제22권4호
• /
• pp.18-25
• /
• 2002

For application to medium temperature solar collerctors $(80\sim120^{\circ}C)$, a heat pipe should be designed properly to efficiently transfer heat to a hotter condenser than common applications. Among many wick structure candidates for heat pipes of this type, a slab wick was selected based on promising performance data reported previously. The thermal performance of slab wick heat pipes, screen wick heat pipes and thermosyphons with enlarged condenser section were experimentally investigated for comparison purpose. The heat pipes were 8.0 mm O.D. (evaporator section) and 25.4 mm O.D. (condenser section) made of copper. The experimental data of the heat pipes were analysed in terms of thermal resistance against thermal load and coolant temperature.

• 마이크로전자및패키징학회지
• /
• 제23권2호
• /
• pp.73-78
• /
• 2016

집적회로(Integrated Circuit) 소자의 트랜지스터(transistor) 밀도 증가는 소자에서 발생하는 열 방출(heat dissipation)의 급격한 상승을 초래하여 열 문제를 발생시키고, 이는 소자의 성능과 열적 신뢰성에 영향을 크게 미친다. 열문제의 해결방안 중 본 연구에서는 냉매를 이용한 액체 냉각방법을 연구하였으며, 실리콘 웨이퍼에 관통실리콘비아(through Si via)와 마이크로 채널(microchannel)을 딥 반응성 이온 애칭(deep reactive ion etching)로 구현한 후 유리기판과 어노딕본딩을 통하여 액체 냉각 구조를 제작하였다. 제작된 마이크로 채널 위에 Ag, Cu 또는 Cr/Au/Cu bump를 스크린프린팅(screen printing) 방법으로 형성하였고, 범프의 유무를 통해 액체 냉각 전후의 냉각 모듈의 실리콘 표면온도의 변화를 적외선현미경으로 분석하였다. Cr/Au/Cu bump가 탑재된 액체 냉각 모듈의 경우 가열온도 $200^{\circ}C$에서 냉각 전후의 실리콘 표면 온도 차이는 약 $45.2^{\circ}C$이고, 전력밀도 감소는 약 $2.8W/cm^2$ 이었다.