• 한국축산식품학회지
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• 제33권6호
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• pp.744-751
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• 2013

The objective of this study was to assess the physicochemical and sensory changes of a kefir manufactured by a two-step fermentation (MTY, $1^{st}$ step: $37^{\circ}C$ for 9 h; $2^{nd}$ step: $24^{\circ}C$ for 15 h) and compare it with kefirs produced by two conventional methods (GTY, fermentation at $37^{\circ}C$ for 24 h; KEY, $22^{\circ}C$ for 24 h). Rapid changes in pH and titratable acidity (TA) were observed in samples from all three manufacturing methods during fermentation process and storage period. Lactic acid bacteria (LAB) counts of MTY increased gradually up to 12 h of fermentation, reaching 9.28 Log CFU/mL, with maximum value observed in this experiment of 9.48 Log CFU/mL. The LAB counts of all samples decreased significantly during storage. The highest viscosity was observed for MTY (1750-1771 cPs), compared with the lowest viscosity observed for KEY (1250-1277 cPs). The viscosity of all samples increased slightly during storage (1250-1805 cPs, p<0.05), as well as carbon dioxide content (0.01-1.36%, p<0.05), except for GTY. The most significant increase in alcohol concentration during storage period was seen in MTY from 0.01% to 1.36% (p<0.05). MTY scored significantly higher in most items of the sensory analysis, indicating that the product manufactured by the two-step fermentation method is more acceptable compared with conventionally produced kefirs.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권2호
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• pp.43-47
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• 2003

Lead zirconate titanate (PZT) thin films were fabricated by the pulsed laser ablation deposition (PLAD) method onto Pt/Ti/SiO$_2$/Si substrates. Crystalline phases as well as preferred orientations in PZT films were investigated by X-ray diffraction analysis (XRD). The well-crystallized perovskite phase and the (101) preferred orientation were obtained by two-step annealing at the conditions of $650^{\circ}C$, 1 hour. It was found that the temperature for the pulsed laser ablated PZT films annealed via a two-step annealing process can be reduced 20$0^{\circ}C$ compared to that of the conventional three-step annealing temperature profile for enhancing the transformation of the perovskite phase. The remanent polarization and the coercive field of this film were about 20 $\mu$C/$\textrm{cm}^2$ and 46 kV/cm, while the dielectric constant and loss values measured at 1 KHz were approximately 860 and 0.04, respectively. The interesting phenomena of this film, such as vertical shift in hysteresis curve, are also discussed.

• 한국결정성장학회지
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• 제11권1호
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• pp.1-5
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• 2001

승화법에 의하여, 여러 조건의 성장압력과 성장온도에서 SiC 단결정을 성장시켰다. 성장된 단결정을 광학현미경으로 관찰하여 성장 step의 형태와 양상을 관찰하였으며, 성장 step의 morphology와 결정 성장 인자와의 상호 연관성에 대하여, 핵생성과 결정성장에 관한 BCF 이론을 적용시켜 고찰하였다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.203-204
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• 2012

CIGS 단일 타켓을 RF 마그네트론 스퍼터링을 이용하여 파워별(20, 40, 60, 80W)로 Mo/SLG위에 증착하여 열처리를 실시하였다. 1step ($350^{\circ}C$), 1step ($550^{\circ}C$), 2step ($350^{\circ}C$, $550^{\circ}C$) 열처리 실시 후 XRD측정 결과 2step 80W에서 가장 좋은 결정성을 확인할 수 있었다. 또한 FE-SEM을 측정결과, 상대적으로 가장 큰 grain size(200nm)를 확인할 수 있었으며 박막의 표면 조도 또한 증가하는 것을 확인할 수 있었다.

• 한국산학기술학회논문지
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• 제13권12호
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• pp.5950-5957
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• 2012

흉부압박의 중단을 최소화하는 심폐소생술은 환자의 생존율 향상을 위한 중요한 요소이다. 본 연구의 목적은 이동 중 주들것에서 보조발판(C-step) 장착 여부에 따른 심폐소생술 정확도 및 오류를 파악하는 데 있다. 연구대상자는 C도 10개 소방서에 근무하고 있는 1급 응급구조사 70명(대조군 35명, 실험군 35명)으로 주들것에서 심폐소생술 정확도가 측정되었다. 연구결과 C-step을 적용한 주들것에서 심폐소생술은 적절한 흉부압박 높이와 안정된 자세를 제공해 흉부압박 정확도를 높이고(t=65.104, p=.000), 인공호흡 시 적절한 환기량을 공급하여 인공호흡 정확도를 높이며(t=5.207, p=.000) 심폐소생술 자신감 또한 향상시키는 것으로 나타났다(t=-10.612, p=.000). 결론적으로 주들것에 C-step 장착은 고품질의 심폐소생술(high quality CPR)을 충실히 수행해 심정지 환자의 생존율을 높이는데 도움이 될 것으로 사료된다.

• 한국임상수의학회지
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• 제35권2호
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• pp.39-45
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• 2018

We evaluated the effects of green tea extract (GTE) supplementation at different dilution steps on boar sperm freezing and in vitro fertilization. Sperm intracellular hydrogen peroxide ($H_2O_2$), motility, viability, acrosome integrity and morphology were determined. In addition, sperm IVF parameters (penetration and monospermy) and glutathione (GSH) levels of presumptive zygotes (PZs) were evaluated. Semen was diluted in lactose egg yolk (LEY) and cooled at $5^{\circ}C$ for 3 h (first dilution step) and then diluted in LEY with 9% glycerol and maintained at $5^{\circ}C$ for 30 min (second dilution step). Four experimental groups were compared: first and second dilution steps without GTE (control), first dilution step with GTE (Step 1), second dilution step with GTE (Step 2) and first and second dilution step with GTE (Step 1+2). The spermatozoa were frozen in nitrogen vapor. Higher sperm motility, viability and acrosome integrity after thawing were observed in Step 1, Step 2 and Step 1+2 groups compared with the control (P < 0.05). Lower $H_2O_2$ level was observed in Step 1+2 compared with control and Step 1 (P < 0.05). For IVF, matured oocytes were co-cultured with spermatozoa frozen according to the experimental groups. GSH levels of PZs were significantly higher in Step 2 and Step 1+2 than in control and Step 1 (P < 0.05) without a significant difference in IVF parameters. In conclusion, supplementation with GTE in both first and second dilution steps during the freezing process resulted in better boar sperm cryopreservation and might be beneficial for further embryo development.

• 한국자기학회지
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• 제2권2호
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• pp.91-98
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• 1992

$Co_{67}Fe_{4.5}Nb_{2}Si_{10}B_{15}$ 비정질합금리본에서 2단 어닐링이 자기특성에 미치는 영향을 조사 하였다. 고온인 $480^{\circ}C$ 이상에서 20분간 1단 어닐링한 리본을 저온인 $310^{\circ}C$에서 2시간 동안 2단으로 진공어닐링한 결과 보자력과 각형비는 1단 어닐링한 경우와 거의 비슷한 값들을 나타내었으나, 직류 및 교류투자율은 1단 어닐링에 비해 현저히 높아졌다. 2단 어닐링시 직류 및 1 kHz에서의 교류투자율의 최대치는 각각 약 290,000과 41,000으로서 1단 어닐링에 비해 30% 이상 증가하였다. 어닐링온도에 따른 자성의 변화는 3단계로 나누어 내부응력, 자구크기, cluster 및 결정상의 변화를 주요 요인으로 하여 고찰하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.529-530
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• 2011

• 소성∙가공
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• 제20권5호
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• pp.357-361
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• 2011

A beryllium copper alloy(C1720) sheet was stretch-drawn using different processes. A hemispherical punch was first used and the forming behavior was examined. Then, cylindrical cups with a hemispherical head were produced by either one-step drawing or two-step forming(sequential stretch forming-drawing). The one-step drawing showed the better formability than two-step forming. However, the two-step forming was the superior process in terms of attaining shape accuracy.

• 한국표면공학회지
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• 제46권1호
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• pp.16-21
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• 2013

CIGS (Cu-In-Ga-Se) films were deposited on the Mo coated soda lime glass (Mo/SLG) by RF magnetron sputtering using a single sintered target with different chemical compositions. Heat treatment of the CIGS films were carried out under three different conditions, 1step ($350^{\circ}C$ for 2 hour and $550^{\circ}C$ for 2 hour) and 2step ($350^{\circ}C$ for 1 hour and $550^{\circ}C$ for 1 hour). In the case of CIGS films post-annealed on 2step method, grain size remarkably increased compared to other methods, indicating that chemical composition [Cu/(Ga+In) = 1] of CIGS films was same as CIGS target. After heat treatment by 2step method, band gap energy of the CIGS film deposited at RF 80 W showed 1.4 eV which is broadly similar to identical band gap energy (1.2 eV) of CIGS film prepared by evaporation method. Therefore, 2step heat treatment method could be expected to low temperature process.