• 한국결정학회지
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• 제11권3호
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• pp.151-156
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• 2000

Yb/YAG single crystals were grown from the melt composition of Y/sub 1-x/Yb/sub x/)₃Al/sub 5/O/sub 12/ where x equal to 5, 10, 15, 20, 25, 33, 50, 75 and 100 at % by floating zone method. Optimum growth parameters to get high quality single crystals were 3.5 mm/h of growth rate and 20 rpm of rotation rate under the N₂ atmosphere. After the growth, color of crystals was appeared with pale blue due to the lack of oxygen, but it was disappeared after annealing at 1450℃ for 2 hr. Absorption coefficients were linearly increased depending on the concentration of Yb/sup 3+/ ions. Broad emission band was measured in the range of 1020 to 1050 nm with the peak intensity at 1031 nm and 1051 nm because of ²F/sub 5/2/(1)→²F/sub 7/2/(3) and ²F/sub 5/2/(1)→²F/sub 7/2/(4) transition respectively. When Yb/sup 3+/ ions were substituted with high rates, there were tendency to decrease the measured fluorescent lifetime for Yb ions depending on the concentration of Yb/sup 3+/ ions.

• 연구논문집
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• 통권33호
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• pp.17-25
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• 2003

In this work, thermal design of a PCR chip for LOC is systematically conducted. From the numerical simulation of a PCR chip based on the finite volume method, how to control the average temperature of a PCR chip and the temperature difference between the denaturation zone and the annealing zone is presented. The average temperature is shown to be controlled by adjusting heat input and a cooler as well as a heater is shown to be necessary to obtain three individual temperature zones for polymerase chain reaction. To reduce the time required, a heat sink for the cooler is not included in the calculation domain for the PCR chip and heat sink design is conducted separately by using a compact modeling method, the porous medium approach.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.412-414
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• 2004

We have developed nucleation control methods applicable to a zone-melting recrystallization excimer laser annealing process for poly-Si films. Ribbon-shaped Si grains of 2 ${\mu}m$-width were successfully aligned side by side by means of a comb-shaped beam, and we have successfully fabricated TFTs with channels formed in those grains. Electron mobility in the TFTs is as high as 677-$cm^2$/Vs.

• 한국결정학회지
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• 제1권1호
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• pp.29-34
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• 1990

할로겐 램프를 열원으로 하는 image furnace를 사용하여 소위 traveling solvent floating zone법에 의해 Mg TiO3(가이킬라이트) 고용체 단결정을 육성했다. 육성된 결정은 직경 8mm, 길이 100mm이였으며 성장측은(1010)이었다. MgTiO, 상은 고온에서 일정한 공용영역을 나타내고 있으며 완만한 속도로 냉각시키면 TiO, 성분이 결정학적 방위의 콘트롤을 받아 (0001)면에 평행하게 용출됨으로써 광채효과를 나타낸다. 육성된 boul은 검은색을 띠고 있으나 1100℃ 산소분위기에서 annealing시킬 경우 반투명한 단양한 색깔을 보여 준다. 따라서 가이킬라이트는 새로운 종류의 인공캣츠아이로 활용될 수 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.140-140
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• 1999

Ti/Ni multilayered films (MLF) are ideal for neutron optics particularly in neutron guides and focusing devices. This system also possesses the tendency of amorphization through a solid-state reaction (SSR). This behaviors are closely related to the electronic structures and both magneto-optical (MO) and optical properties of metals depend strongly on their electron energy structures. Mutual inter-diffusion of the Tin and Ni atoms in the MLF caused by a low temperature annealing should decrease the thickness of pure Ni, as well as change the chemical and atomic order in the reactive zone. The application of the MO spectroscopy to the study of SSR in the MLF allows us to obtain an additional information on the changes in the atomic and chemical orders in the interface region. The optical one has no restriction on the magnetic state of the constituent sublayers. Therefore, the changes in magnetic, MO and optical properties of the Ti/Ni MLF due to SSR can be expected. To the best of our knowledge, the MO and optical spectroscopies were not used for this purpose. SSR has been studied in the series of the Ti/Ni MLFs with bilayer periods of 0.65-22.2nm and constant ratio of the Ti to Ni sublayers thickness by using MO and optical spectroscopies as well as an x-ray diffraction. The experimental MO and optical spectra are compared with the computer-simulated spectra, assuming various interface models. The relative changes in the x-ray diffraction spectra and MO properties of the Ti/Ni MLF caused by annealing are bigger for the multilayers with "thick" sublayers, or the SSR with the formation of amorphous alloy takes place mainly in the Ti/Ni multilayers with "thick" sublayers, while in the nominal threshold thickness of the Ni-sublayer for the observation of the equatorial Kerr effect in the as-deposited and annealed Ti/Ni MLFs of about 3.0 and 4.5nm thick is explained by the formation of amorphous alloy during the deposition or the formation of the nonmagnetic alloyed regions between pure components as a result of the SSR. For the case of Ti/Ni MLF the MO approach is more sensitive for the determination of the thickness of the reacted zone, while x-ray diffraction is more useful for structural analyses.structural analyses.

• 한국세라믹학회지
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• 제43권9호
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• pp.544-551
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• 2006

The sealing technique between a glass tube and a copper heat pipe in an evacuated tube solar collector is studied. In this study two different sealing techniques, such as flame method and furnace firing, are examined. After the sealing of a copper to a glass, the oxidation state of the copper and its bonding morphology were examined by SEM and XRD. Its oxidation was retarded by coating of borate solution on the copper, and $Cu_2O(cuprite)$ turned into CuO(tenorite) with increase in a firing temperature and firing time. Porous structure was found in the oxide layer when CuO formed. The best sealing morphology was observed when the thickness of the oxidation layer was less than $20{\mu}m$. The sealing technique performed in a furnace was promising and the satisfactory result was obtained when the sample was fired at $950^{\circ}C$ for 5 min under $N_2$ atmosphere. Annealing procedure is recommended to remove the stress left at the bonding zone.

• Nuclear Engineering and Technology
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• 제20권2호
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• pp.105-111
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• 1988

과망간산염들, 즉 과망간산 칼륨, 과망간산 암모늄, 과망간산 바륨에서 망간의 중성자 포획으로 야기되는 화학적 효과를 고찰하였다. $^{55}$Mn(n, ｒ) $^{56}$ Mn 반응에서 생성된 방사성 망간 화학종, 즉 양이온 56/Mn, $^{56}$ MnO$_2$ 그리고 $^{56}$ MnO$_4$$^{-}$의 분포에 미치는 용제의 pH효과를 여러 가지 흡착제들과 이온교환체, 즉 제올이프 A-3, 카올리나이트, 알루미나, 이산화망간 그리고 도엑스 -50을 이용하여 고찰하였다. 카올리나이트와 알루미나에서 방사성 MnO$_4$$^{-}$의 분포가 대표적인 pH값인 4, 7 그리고 9 각각에서 다른흡착제와 이온교환체보다 높게 나타나며 동일한 흡착제일경우에는 pH 4 는 및 pH 9에서가 pH 7에서보다 높게 나타난다. $^{55}$Mn(n, ｒ) $^{56}$ Mn 반응에 의하여 과망간산염에서 생성된 반조망간원자들의 열-어니어링 거동 또한 고찰하였다. 열-어니어링에서 $^{56}$ MnO$_4$$^{-}$의 잔류율은 10$0^{\circ}C$ 및 13$0^{\circ}C$ 처리에서 온도가 높아질수록 증가함을 보였다. 망간염의 반조효과는 hot zone model로 설명하였다.

• 터널과지하공간
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• 제17권6호
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• pp.493-502
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• 2007

암반의 수리적 특성 및 지하수 유동 양상을 파악하는데 요구되는 수리전도도맵 작성시, 투수시험 자료의 자료수 한계를 극복하고 수리전도도맵의 신뢰도 향상을 목적으로 물리탐사 결과 자료와의 병합툴을 개발하고 현장 적용해 보았다. 개발된 병합툴은 지구통계학적 최적화 시뮬레이션 기법 중의 하나인 모의 담금질 기법(Simulated Annealing)을 활용하였으며, 시뮬레이션에 필요한 전처리 과정과 후처리 과정을 포함한 4개의 모듈로 구성되었다. 파쇄대 수리특성의 파악 및 가시화를 위한 현장 적용 결과, 시추공 사이의 비조사 영역에서의 투수특성의 변화를 파악하는데 유용하게 적용될 수 있음을 확인하였다.

• Corrosion Science and Technology
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• 제20권6호
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• pp.426-434
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• 2021

The effect of two different annealing temperatures on the level of the second phase precipitated in the microstructure and the corrosion behaviors of super austenitic stainless steel were examined. The sample annealed at a higher temperature had a significantly lower fraction of the sigma phase enriched with Cr and Mo elements, showing more stable passivity behavior during the potentiodynamic polarization measurement. However, after the welding process with Inconel-type welding material, severe corrosion damage along the interface between the base metal and the weld metal was observed regardless of the annealing temperature. This was closely associated with the precipitation of the fine sigma phase with a high Mo concentration in the unmixed zone (UMZ) during the welding process, leading to the local depletion of Mo concentrations around the sigma phase. On the other hand, the fraction of the newly precipitated fine sigma phase in the UMZ was greatly reduced by post-weld heat treatment (PWHT), and the corrosion resistance was greatly improved. Based on the results, it is proposed that the alloy composition of welding materials and PWHT conditions should be further optimized to ensure the superior corrosion resistance of welded super austenitic stainless steel.

• 한국세라믹학회지
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• 제41권10호
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• pp.771-776
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• 2004

Zr을 $8\%$ 첨가한 BZT 세라믹스를 종결정과 소재봉으로 사용하여 floating zone technique법으로 $Ba(Zr_{0.08}Ti_{0.92})O_3$ 다결정을 성장하였다. 열처리 효과를 알아보기 위하여 성장한 결정의 일부를 떼어내어 $1,200^{\circ}C$에서 10시간동안 산소 분위기에서 열처리하였다. $-100^{\circ}C$에서 $+150^{\circ}C$ 온도 영역에서 유전상수 및 유전손실을 10kHz, 100kHz, 그리고 1 MHz에서 측정하여 성장 결정의 유전특성을 알아보았다. 상온($27^{\circ}C$)과 저온($-73^{\circ}C$)에서 직류전장(-15kV/cm$\le$E$\le$15kV/cm)을 인가하면서 유전상수의 변화를 10kHz와 100kHz에서 측정함으로써 유전상수의 전장의존성을 알아보았다. 산소 열처리는 상온에서 10kHz의 튜너빌리티를 $47.5\%$에서 $51\%$로, 그리고 성능지수를 39.6에서 46.4로 향상시키었다. 바이어스 직류전장을 15kV/cm 이상 인가하면 성능지수가 46.4 이상으로 향상될 수 있으므로 이 물질이 마이크로파 전장 조절 소자에 응용될 수 있는 가능성이 있다.