• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.139-142
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• 2002

Characteristics of piezoelectric thick films prepared by screen printing were investigated. The piezoelectric thick films were fabricated using Pb(Al,Nb)O$_3$-Pb(Zr,Ti)O$_3$ system on Si-substrate. The fabricated thick films were burned out at 400$^{\circ}C$ and sintered at 850∼1000$^{\circ}C$ using rapid thermal annealing(RTA) precess. The thickness of piezoelectric thick films were 10$\mu\textrm{m}$. PAN-PZT thick film on Ag-Pd/SiO$_2$/Si prepared at 900$^{\circ}C$/1300sec had remanent polarization of 19.70 ${\mu}$C/$\textrm{cm}^2$.

• 천문학회보
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• 제43권1호
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• pp.67.2-67.2
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• 2018

Magnetic fields play an important role in star-forming processes by regulating gravitational collapse. In filamentary structures of star-forming regions, magnetic fields are likely to be aligned with minor axes of filamentary molecular clouds because matter freely moves along magnetic field lines. Orion A region, one of the well-known high-mass star forming regions, has long filament structure. In order to study magnetic field directions with respect to the filamentary structure in Orion A, we have analyzed $850{\mu}m$ dust polarization observations obtained with the James Clerk Maxwell Telescope (JCMT). We found tight correlation of dust intensity gradients and magnetic field directions. It was estimated that 81% of magnetic field segments are aligned with density gradients within 40 degree. In conclusion, we confirmed most of magnetic field segments are perpendicular to the major axis of the filament in Orion A.

• 동력기계공학회지
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• 제12권1호
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• pp.66-71
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• 2008

Alumium alloys hot forging process are gaining increased acceptance in the automotive and electronic industries and hot forging is one of the most efficient manufacturing method for mass product parts. It has been investigated the microstructures and mechanical properties of Al-11.7Si-0.5Mg (KNT40-T6)alloy fabricated by hot forging process for development of connecting rod in this study. The microstructure of hot forged specimen was composed of eutectic structure of alumimum solid solution and $Mg_2Si$ precipitates. The tensile strength of solutionized Al-11.7Si-0.5Mg alloy was 217MPa. This alloy showed a good corrosion resistance using electrochemical polarization test.

• E2M - 전기 전자와 첨단 소재
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• 제7권5호
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• pp.369-375
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• 1994

In this study, ferroelectric thin films of PZT with different Zr/Ti ratio were prepared by sol-get processing and annealed by rapid thermal annealing at >$500^{\circ}C$>$-700^{\circ}C$ for 10 sec. -1 min. Structures of the annealed films were examined by X-ray diffraction and SEM. Thin films of PZT with perovskite structure have been obtained by annealing at >$600^{\circ}C$ or above and for 20 seconds or longer. Maximum remnant polarization of 10.24.mu.C/cm$^{2}$ and minimum coercive field of 20.06 kV/cm were obtained from the 56/44 and 65/35 Zr/Ti composition films, respectively. Dielectric constant, .epsilon.$_{r}$ of 500-1300 and dielectric loss, tan .delta., of 0.01-0.035 were obtained from the films.s.

• Current Optics and Photonics
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• 제2권6호
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• pp.519-524
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• 2018

We propose a transverse load sensor with reconfigurable measurement accuracy based on a microwave photonic filter in the $K_u$ band, incorporating a polarization-maintaining fiber Bragg grating. A prototype sensor with a reconfigurable measurement accuracy tuning range from 6.09 to 9.56 GHz/(N/mm), and corresponding minimal detectable load range from 0.0167 to 0.0263 N/mm, is experimentally demonstrated. The results illustrate that up to 40% manufacturing error in the grating length can be dynamically calibrated to the same corresponding measurement accuracy for the proposed transverse load sensor, by controlling the semiconductor optical amplifier's injection current in the range of 154 to 419 mA.

• 공업화학
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• 제33권3호
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• pp.315-321
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• 2022

We firstly observed that activated carbon (AC) deposited by atomic-layer vanadium pentoxide (V₂O₅) was used as CDI electrodes to utilize the high dielectric constant for enhancing the capacitance equipped with atomic layer deposition (ALD). It was demonstrated that the vanadium pentoxide (V₂O₅) with sub-nanometer layer was effectively deposited onto activated carbon, and the electric double-layer capacitance of the AC was improved due to an increase in the surface charge density originated from polarization, leading to high ion removal in CDI operation. It was confirmed that the performance of modified-AC increases more than 200%, comparable to that of pristine-AC under 1.5 V at 20 mL min^-1 in CDI measurements.

• 한국수자원학회논문집
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• 제48권11호
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• pp.925-936
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• 2015

본 연구의 목적은 이중편파 레이더 강우자료와 격자기반 분포형 강우-유출 모형인 KIMSTORM(KIneMatic wave STOrm Runoff Model)을 이용하여 유출해석을 수행하고, 침수실적자료와의 비교를 통해 레이더 강우자료의 효용성을 검토하는데 있다. 남강댐유역($2,293km^2$)을 대상으로, 2012년 4개의 강우 이벤트(집중호우, 카눈, 볼라벤, 산바)에 대하여 비슬산 레이더 강우자료를 사용하였다. 분포형 모형은 28개 지점 강우와 레이더 강우를 이용하여 보정되었으며, $R^2$(coefficient of determination), ME(model efficiency), VCI(volume conservation index)를 이용하여 적용성을 평가하였다. 모형의 보정결과, $R^2$, ME, VCI의 평균이 지점강우를 이용한 경우 각각 0.85, 0.78, 1.09, 레이더 강우를 이용한 경우 각각 0.85, 0.78, 0.96의 결과를 보였다. 태풍 산바에 의한 하천범람 침수실적자료의 두 침수지역(신연지구와 문대/신기지구)과 레이더와 지상강우에 의한 유출분석 결과를 비교하였다. 신연지구와 문대/신기지구 두 침수지역에서 레이더강우가 지상강우보다 더 많은 지역강우를 발생시켜 지표유출량을 더 크게 모의하는 것을 확인할 수 있었다. 특히 수위관측소가 존재하는 문대/신기지구의 경우, 지점강우보다 레이더 강우가 침수지역내 수위관측소의 실제 첨두유량에 가깝게 모의하였으며, 하천수위도 0.72m 높게 모의하였다.

• Applied Science and Convergence Technology
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• 제26권4호
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• pp.70-73
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• 2017

The dielectric constant and loss of poling/non-poling was measured in the $Pb_{1-3x/2}La_x[(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ samples. The addition of $La^{3+}$ to the $Pb_{1-3x/2}La_x[(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ did not cause a large change in grain size. But the addition of $La^{3+}$ did show transition temperature, which shifted toward low temperature in the $Pb[(Mg_{1/3}Ta_{2/3})Zr]O_3$ systems. In addition, the dielectric and pyroelectric properties (${\varepsilon}{\sim}20000$, $p{\sim}0.03C/m^2K$) of this system using $La^{3+}$ have been greatly improved. Pyroelectrics $Pb_{0.97}La_{0.02}(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ system was found to have a relatively high ferroelectric FOMs ($F_V{\sim}0.035m^2/C$, $F_D{\sim}0.52{\times}10^{-4}Pa^{-1/2}$) at room temperature. Spontaneous polarization showed a value of $0.27{\sim}0.35C/m^2$ in the composition added to $La^{3+}$. The piezoelectric constant ($d_{33}=350{\sim}490pC/N$) and electromechanical coupling factor ($k_P=0.25{\sim}0.35$) are obtained in $Pb_{1-3x/2}La_x[(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ compositions with $La^{3+}$ dopant.

• 마이크로전자및패키징학회지
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• 제12권2호
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• pp.167-174
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• 2005

전자 부품의 크기가 점점 줄어들고 고집적화됨에 따라 전자 패키지 내부에 사용되는 금속간 간격이 줄어들고 있다. 이에 더하여 고온 고습한 환경에서 금속간에 전압이 인가되면 금속의 이온화가 촉진, 금속으로 이루어진 필라멘트가 형성되어 결국 절연파괴에 이르게 된다. 이러한 현상이 electrochemical migration(ECM)이다. 이에 인쇄회로기판을 사용하여 ECM 특성 평가를 수행하였다. 항온/항습조건($85^{\circ}C,\;85{\%}RH$)에서 PCB의 $300 {\mu}m$의 단자간격을 가진 through-hole via 표면에서 발생하는 ECM 현상은 CAF가 절연파괴의 주된 메커니즘이었다. solder를 구성하는 Sn과 Pb 조성 분석을 통해 Pb 의 이온 이동도가 Sn의 이온 이동도보다 큰 것을 알 수 있었으며 이는 급격한 양극용해 거동을 보이는 pure Pb의 분극거동과 상관관계가 있는 것으로 사료된다. 또한 시간에 따른 절연파괴시간 시험을 통하여 ECM에 의한 절연파괴시간이 인가전압에 의존하며 인가전압 의존성 지수값(n)은 2로 나타났다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권8호
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• pp.387-391
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• 2006

The Ag photodoping effect in amorphous $As_{40}Ge_{10}Se_{15}S_{35}$ chalcogenide thin films for holographic recording has been investigated using a He-Ne laser (${\lambda}$=632.8 nm). The chalcogenide films thickness prepared in the present work were thinner in comparison with the penetration depth of recording light ($d_p=1.66{\mu}m$). It exhibits a tendency of the variation of the diffraction efficiency (${\eta}$) in amorphous chalcogende films, independently of the Ag photodoping. That is, ${\eta}$ increases rapidly at the beginning of the recording process and reaches the maximum (${\eta}_{max}$) and slowly decreases slowly with the exposed time. In addition, the value of ${\eta}_{max}$ depends strongly on chalcogenide film thickness(d) and its maximum peak among the films with d = 40, 80, 150, 300, and 633 nm is observed 0.083% at d = 150 nm (approximately 1/2 ${\Delta}n$), where ${\Delta}$n is the refractive index of chalcogenide thin film (${\Delta}n=2.0$). The ${\eta}$ is largely enhanced by Ag photodoping into the chakogenides. In particular, the value of ${\eta}_{max}$ in a bilayer of 10-nm-thick Ag/150-nm-thick $As_{40}Ge_{10}Se_{15}S_{35}$ film is about 1.6%, which corresponds to ${\sim}20$ times larger than that of the single-layer $As_{40}Ge_{10}Se_{15}S_{35}$ thin film (without Ag). And we obtained the diffraction pattern according to the formation of (P:P) polarization holographic grating using Mask pattern and SLM.