• 센서학회지
• /
• 제20권2호
• /
• pp.82-89
• /
• 2011

Ruthenium(Ru)-doped $TiO_2$ nanofibers were prepared using electrospun Ru-$TiO_2$/poly(vinyl acetate) (PVAc) fibers and subsequent annealing for 1 h at temperatures in the range of $500^{\circ}C$ to $1000^{\circ}C$ in air. The properties of the Ru-$TiO_2$ fibers were characterized as a function of the Ru content and calcination temperature using X-ray diffraction, thermal gravimetry with differential scanning calorimetry, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and viscometer, pycnometer and dynamic tensiometer measurements. Although the diameter of the fiber decreased slightly with increasing calcination temperature, no dramatic changes were observed with respect to the ruthenium content. The XRD and FT-IR results revealed that anatase phase and ruthenium metal began to be formed after calcination at temperatures above $500^{\circ}C$. Anatase and rutile phases and ruthenium metal coexisted in the fibers calcined above $600^{\circ}C$. No anatase phase was detected in the fibers containing ruthenium when they were calcined at $1000^{\circ}C$. The morphology of the fibers changed from smooth and uniform to porous with increasing temperature. The experimental results suggest that the calcination temperature and Ru content were influential in determining the morphology and structure of the fibers.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 추계학술대회 논문집
• /
• pp.1033-1036
• /
• 2002

Wafer bonding methods such as fusion and anodic bonding suffer from high temperature treatment, long processing time, and possible damage to the micro-scale sensor or actuators. In the localized bonding process, beating was conducted locally while the whole wafer is maintained at a relatively low temperature. But previous research of localized heating has some problems, such as non-uniform soldering due to non-uniform heating and micro crack formation on the glass capsule by thermal stress effect. To address this non-uniformity problem, a new heater configuration is being proposed. By keeping several points on the heater strip at calculated and constant potential, more uniform heating, hence more reliable wafer bonding could be achieved. The proposed scheme has been successfully demonstrated, and the result shows that it will be very useful in hermetic packaging. Less than 0.2 ㎫ contact Pressure were used for bonding with 150 ㎃ current input for 50${\mu}{\textrm}{m}$ width, 2${\mu}{\textrm}{m}$ height and 8mm $\times$ 8mm, 5mm$\times$5mm, 3mm $\times$ 3mm sized phosphorus-doped poly-silicon micro heater. The temperature can be raised at the bonding region to 80$0^{\circ}C$, and it was enough to achieve a strong and reliable bonding in 3minutes. The IR camera test results show improved uniformity in heat distribution compared with conventional micro heaters. For gross leak check, IPA (Isopropanol Alcohol) was used. Since IPA has better wetability than water, it can easily penetrate small openings, and is more suitable for gross leak check. The pass ratio of bonded dies was 70%, for conventional localized heating, and 85% for newly developed FP scheme. The bonding strength was more than 30㎫ for FP scheme packaging, which shows that FP scheme can be a good candidate for micro scale hermetic packaging.

• 센서학회지
• /
• 제6권6호
• /
• pp.491-499
• /
• 1997

초전재료의 개발 및 박막화를 위하여 5, 10 및 15 mol%의 La 조성을 가지는 세라믹 PLT 시편 및 박막 PLT를 제조하여 그 특성을 분석하였다. PLT의 완전 소결과 Pb 성분의 휘발을 막기 위하여 TG/DTA를 사용하여 하소 및 소결온도를 결정하였다. PLT 세라믹 시편을 제조하기 위한 하소 및 소결온도는 각각 $850^{\circ}C$, $1150^{\circ}C$ 이고 더 높은 소결온도에서는 많은 질량 손실이 발생하였다. 세라믹 시편을 사용한 온도-유전율 특성의 측정으로 La 조성에 따른 PLT의 온도에 대한 유전특성을 조사하였다. 5, 10 및 15 mol%의 La 농도에 따라 PLT의 상전이점은 각각 $330^{\circ}C$, $269^{\circ}C$ 및 $210^{\circ}C$를 나타내었다. 제조된 PLT 시편을 사용하여 적외선 감지 특성을 확인하였고, 고주파 마그네트론 스퍼터링을 이용하여 PLT 박막을 증착하였다. 다음으로 격자상수 및 광투과 특성을 통하여 완전 소결된 PLT 타겟으로 제작한 PLT 박막은 타겟과 동일한 구조를 가지고 있음을 확인하였다.

• 한국항공우주학회지
• /
• 제38권6호
• /
• pp.577-585
• /
• 2010

본 논문은 태양복사에너지를 고려한 지상 물체에서 방출되는 적외선 복사휘도를 예측하는 소프트웨어 개발 중 BRDF 데이터를 고려한 적외선 복사휘도를 분석한 내용을 다루었다. 물체 표면에서 방출되는 적외선 복사휘도는 물체의 표면온도 및 광학적 표면 특성을 이용하여 계산할 수 있다. BRDF는 물체 표면에 입사되는 에너지와 반사되는 에너지의 관계로 나타낼 수 있는 백분율로 정의하며 적외선 복사휘도를 분석하는 데 매우 중요한 자료로 사용된다. 본 논문에서는 중적외선 및 원적외선 영역에 대하여 태양이 존재하는 시간동안 다양한 재질의 광학적 표면 특성에 따른 적외선 영상을 생성하여 분석하였다. 연구결과 물체 표면의 복사율 및 BRDF 등은 물체의 적외선 영상에 매우 중요한 영향을 미치는 것을 확인하였으며, 특히 태양의 영향을 받을 경우 MWIR 영역의 복사휘도는 수치적으로 최대 10배까지 신호량의 차이를 보일 수 있음을 확인하였다.

• 센서학회지
• /
• 제7권1호
• /
• pp.51-60
• /
• 1998

초전형 적외선센서를 제조하기 위하여 La가 첨가된 $PbTiO_{3}$(PLT)박편을 소결온도, La첨가량 및 소결시의 분위기분말의 양과 같은 제조조건을 달리하면서 제조하여 이에 따른 시편의 구조적 특성을 X-선 회절기, 전자현미경 및 상대밀도의 측정을 통하여, 유전특성을 유전상수와 큐리온도 등의 측정을 통하여 조사하였다. La 첨가랑이 증가함에 따라 정방성비 c/a는 감소하였으며, 상대밀도 및 입자의 크기는 증가하였다. 이는 La 첨가량이 증가함에 따라 전하중성을 유지하기 위한 Pb공공의 증가에 기인하는 것으로 판단된다. 소결시 분위기분말의 증가는 La 첨가에 따른 효과에 비해 미미하지만 정방성비를 미세하게나마 증가시켜 PbO의 휘발을 감소시키는 것으로 나타났다. La 첨가량에 따른 정방성비의 감소로 상온에서의 유전상수는 증가하였으며 큐리온도는 감소하였다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.222-227
• /
• 2003

Recent advances in room-temperature, visible and near-IR diode laser sources for telecommunication, optical data storage applications are enabling combustion diagnostics system based on diode laser absorption spectroscopy. In contrast to some traditional sampling-based gas-sensing instruments, tunable diode laser absorption spectroscopy system is advantageous because of their non-invasive nature, high sensitivity, fast response time and real-time measurement capability. So, combined with fiber-optics and high sensitive detection strategies, compact and portable sensor system arc now appearing for a variety of applications. The objective of this research is to take advantage of distributed feed-back diode laser and measure the $CO_{2}$ concentration (by using direct absorption and wavelength modulation spectroscopy methods). In addition to survey spectra of $CO_{2}$ bands and spectroscopic parameters between 1565 and 1579 run were computed at temperatures between 296 and 1200 K (by using HITRAN 2000 database). It experimentally found out that the features of direct absorption and wavelength modulation spectroscopy methods.

• 한국광학회지
• /
• 제18권2호
• /
• pp.135-141
• /
• 2007

완전한 2차원 배열을 갖는 중적외선 대역의 $320\times240$ 검출기를 사용하는 3세대 열상 장비의 설계 및 제작은 이차원 배열 검출기 제작 기술의 발달과 영상 신호처리 기술의 진전으로 인해 최근 더욱 더 활발히 이루어지고 있다. 본 논문은 다양한 응용 분야에서 적외선 센서로 사용될 수 있도록 하기 위하여 소형 경량화 제작을 목표로 한 3세대 열상장비의 이중 배율 적외선 카메라의 설계와 Defocus용 셔터 렌즈에 의한 영상기반 불균일 보정 방식에 대해 다룬다.

• 센서학회지
• /
• 제19권5호
• /
• pp.398-402
• /
• 2010

The liquid phase epitaxy(LPE) method was widely used to growth of mercury cadmium telluride(MCT) thin films. However, this method lead to Hg-vacancies in MCT thin film, because Hg has high vapor pressure at this temperature range. This is a well known defect in HgCdTe grown by LPE method. In this study, we report the development of techniques for improving the crystalline quality and controlling the composite uniformity of HgCdTe thin films using high- pressure Hg-ambient annealing method. As a result, we achieved the improvement of the composite uniformity of HgCdTe thin films. It was observed by the high angle annular dark field scanning TEM(HAADF-STEM) analysis. Moreover, new HgTe phase and a shrinking of lattice fringe were observed.

• 대한원격탐사학회지
• /
• 제22권3호
• /
• pp.175-182
• /
• 2006

Because of the phenological variation of vegetation growth in temperate region, it is often difficult to accurately assess the surface conditions of agricultural croplands, grasslands, and disturbed forests by multi-spectral remote sensor data. In particular, the spectral similarity between soil and dry vegetation has been a primary problem to correctly appraise the surface conditions during the non-growing seasons in temperature region. This study analyzes the spectral characteristics of the mixture of dry vegetation and soil. The reflectance spectra were obtained from laboratory spectroradiometer measurement (GER-2600) and from EO-1 Hyperion image data. The reflectance spectra of several samples having different level of dry vegetation fractions show similar pattern from both lab measurement and hyperspectral image. Red-edge near 700nm and shortwave IR near 2,200nm are more sensitive to the fraction of dry vegetation. The use of hyperspectral data would allow us for better separation between bare soils and other surfaces covered by dry vegetation during the leaf-off season.

• Korean Chemical Engineering Research
• /
• 제57권2호
• /
• pp.259-266
• /
• 2019

Tuning of electro-optical properties of nano-structured $SnO_2:Ga$ powders in a micro drop fluidized reactor (MDFR) was highly effective to enhance the activities of powders to be used as sensor materials. The tuning was conducted continuously in a facile one-step process during the formation of powders. The microscopic hydrodynamic forces affected the band gap structure and charge transfer of $SnO_2:Ga$ powders through the oxygen and interfacial tin vacancies by providing plausible pyro-hydraulic conditions, which resulted in the decrease in the electrical resistance of the materials. The analyses of room-temperature photoluminescence (PL) spectra and FT-IR exhibited that the tuning could improve the surface activities of $SnO_2:Ga$ powders by adjusting the excitation as well as separation of electrons and holes, thus maximizing the oxygen vacancies at the surface of the powders. The scheme of photocatalytic mechanism of $SnO_2:Ga$ powders was also discussed.