• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
• /
• pp.207-210
• /
• 2005

In order to investigate the influence of the homo buffer layer on the microstructure of the ZnO thin film, undoped ZnO buffer layer were deposited on sapphire (0001) substrates by ultra high vaccum pulsed laser deposition (UHV-PLD) and molecular beam eiptaxy (MBE). After high temperature annealing at $600^{\circ}C$ for 30min, undoped ZnO buffer layer was deposited with various oxygen pressure (35~350mtorr). On the grown layer of undoped ZnO, Arsenic-doped(l, 3wt%) ZnO layers were deposited by UHV-PLD. The optical property of the ZnO was analyzed by the photoluminescence (PL) measurement. From $\Theta-2\Theta$ XRD analysis, all the films showed strong (0002) diffraction peak, and this indicates that the grains grew uniformly with the c-axis perpendicular to the substrate surface. Field emission scanning electron microscope (FE-SEM) revealed that microstructures of the ZnO were varied with oxygen pressure, arsenic doping level, and the deposition method of undoped ZnO buffer layers. The films became denser and smoother in the cases of introducing MBE-buffer layer and lower oxygen pressure during As-doped ZnO deposition. Higher As-doping concentration enhanced the columnar-character of the films.

• 산업진흥연구
• /
• 제6권4호
• /
• pp.1-9
• /
• 2021

본 연구는 정수슬러지의 활용을 위하여 경량골재를 제조하고, 그 물성을 확인하기 위하여 경량골재의 특성과 그 활용가능성을 확인하는 것이다. 경량골재 원료로써 특성을 알아보기 위하여 화학조성 및 열적 특성에 대하여 검토하였다. 급속소성법을 이용하여 골재를 소성하고 물성을 측정하였다. 정수슬러지는 높은 강열감량을 가지고 있었으며, 높은 내화도를 가지고 있었다. 정수슬러지를 30wt% 첨가하였을 때 1,150~1,200℃의 온도에서 경량화되는 것을 확인할 수 있었고, 1200℃이상의 온도에서 밀도 0.8이하의 초경량골재도 제조할 수 있었다. 일반골재를 대체하여 콘크리트에 적용 시 28일 강도가 200~600kgf/cm²를 갖는 공시체를 얻을 수 있었으며, 여과재 시험 시 일반모래와 동등 이상의 성능을 나타냈다.

• 청정기술
• /
• 제15권2호
• /
• pp.69-74
• /
• 2009

초임계이산화탄소와 공용매의 혼합물을 사용하여 반도체 웨이퍼 기판으로부터 고농도이온주입 포토레지스트(HDIPR)를 제거하였다. 또한 고압 셀 내부에 초음파 장치를 부착하여 웨이퍼 표면에 물리적 힘을 제공함으로서 세정용액의 HDIPR에 대한 스트리핑 성능을 현저히 향상시키고, 제거 시간을 단축시켰다. 공용매의 종류 및 농도, 공정 온도, 압력 변화에 따른 HDIPR 스트리핑 특성을 조사하였으며, 웨이퍼 표면의 제거 전후의 상태 및 성분을 scanning electron microscopy 과 energy dispersive X-ray spectrometer를 이용하여 분석하였다. 10 w/w% 함량의 아세톤 공용매를 이용하여 공정압력 27.6 MPa과 온도 343 K 의 조건에서 3분의 초음파 처리시간을 거쳐 HDIPR을 완전히 제거할 수 있었다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.77-77
• /
• 2016

Thin films synthesized by plasma processes have been widely applied in a variety of industrial sectors. The structure control of thin film is one of prime factor in most of these applications. It is well known that the structure of this film is closely associated with plasma parameters and species of plasma which are electrons, ions, radical and neutrals in plasma processes. However the precise control of structure by plasma process is still limited due to inherent complexity, reproducibility and control problems in practical implementation of plasma processing. Therefore the study on the fundamental physical properties that govern the plasmas becomes more crucial for molecular scale control of film structure and corresponding properties for new generation nano scale film materials development and application. The thin films are formed through nucleation and growth stages during thin film depostion. Such stages involve adsorption, surface diffusion, chemical binding and other atomic processes at surfaces. This requires identification, determination and quantification of the surface activity of the species in the plasma. Specifically, the ions and neutrals have kinetic energies ranging from ~ thermal up to tens of eV, which are generated by electron impact of the polyatomic precursor, gas phase reaction, and interactions with the substrate and reactor walls. The present work highlights these aspects for the controlled and low-temperature plasma enhanced chemical vapour disposition (PECVD) of Si-based films like crystalline Si (c-Si), Si-quantum dot, and sputtered crystalline C by the design and control of radicals, plasmas and the deposition energy. Additionally, there is growing demand on the low-temperature deposition process with low hydrogen content by PECVD. The deposition temperature can be reduced significantly by utilizing alternative plasma concepts to lower the reaction activation energy. Evolution in this area continues and has recently produced solutions by increasing the plasma excitation frequency from radio frequency to ultra high frequency (UHF) and in the range of microwave. In this sense, the necessity of dedicated experimental studies, diagnostics and computer modelling of process plasmas to quantify the effect of the unique chemistry and structure of the growing film by radical and plasma control is realized. Different low-temperature PECVD processes using RF, UHF, and RF/UHF hybrid plasmas along with magnetron sputtering plasmas are investigated using numerous diagnostics and film analysis tools. The broad outlook of this work also outlines some of the 'Grand Scientific Challenges' to which significant contributions from plasma nanoscience-related research can be foreseen.

• 농업과학연구
• /
• 제6권2호
• /
• pp.158-165
• /
• 1979

우리나라에서 처리(處理) 유통(流通)되고 있는 초고온살균유(超高溫殺菌乳)의 선도(鮮度) 및 세균학적(細菌學的) 상태(狀態)를 확인(確認)함과 동시에 냉장(冷藏) 및 실온(室溫)에 있어서의 보존성(保存性)을 검토(儉討)하기 위하여 사개지역(四個地域)(광주(光州), 대전(大田), 성환(成歡), 서울)의 초고온살균병유(超高溫殺菌甁乳)를 수집(蒐集)하여 신선도검사(新鮮度檢査)와 미생물학적(微生物學的) 상태(狀態)를 시험(試驗)하여 다음과 같은 결과(結果)를 얻었다. 1. 초고온살균유(超高溫殺菌乳)를 $4^{\circ}C$에 보존(保存)할 때에는 3개(個) 시유(市乳)가 9일(日)에 이르기까지 1개(個) 시유(市乳)는 5일(日)까지 기준산도(基準酸度)를 상회(上廻)하지 않았으며 $20^{\circ}C$에 보존(保存)할 때에는 3(개)個 시유(市乳)는 1일(日)까지 1개(個) 시유(市乳)는 즉일(卽日)만이 기준산도(基準酸度)를 유지(維持)하였다. 2. 초고온살균유(超高溫殺菌乳)의 신선도(新鮮度) 확인(確認)을 위한 주정시험(酒精試驗)과 자비시험(煮沸試驗) 결과(結果) $4^{\circ}C$ 보존(保存)의 경우 3개(個) 시유(市乳)는 10일(日)까지 음성(陰性)을 나타내고 1개(個) 시유(市乳)는 6~7일(日)부터 양성(陽性)을 나타내었으며 $20^{\circ}C$에 보존(保存)할 때에는 3개(個) 시유(市乳)가 2일(日)부터 1개(個) 시유(市乳)는 1일(日)부터 양성(陽性)을 나타내었다. 3. 초고온살균유(超高溫殺菌乳)의 생균수(生菌數)는 $4^{\circ}C$ 보존(保存)의 경우 1개(個) 시유(市乳)는 10일(日)까지 2개(個) 시유(市乳)는 7일(日)까지 1개(個) 시유(市乳)는 2일(日)까지 허용(許容) 기준세균수(基準細菌數)를 나타내고 $20^{\circ}C$ 보존(保存)에 있어서는 1개(個) 시유(市乳)만이 1일(日)까지 3개(個) 시유(市乳)는 즉일(卽日)만이 허용기준(許容基準)의 세균수(細菌數)를 나타내었다. 4. 호냉성세균수(好冷性細菌數)는 $4^{\circ}C$에 보존(保存)할 경우 평균(平均) $4.8{\times}10^3/ml$로부터 점차(漸次) 증가(增加)하여 10일(日)에는 평균(平均) $6.4{\times}10^7/ml$에 이르렀으며 $20^{\circ}C$에 보존(保存)할 때에는 2일(日)에 $5.2{\times}10^7/ml$로 증가(增加)하였다. 5. 내열성균(耐熱性菌)에 있어서는 $4^{\circ}C$로 보존(保存)하였을때 3개(個) 시유(市乳)가 10일(日)까지 1개(個) 시유(市乳)는 6일(日)까지 <$10^2$의 세균수(細菌數)를 나타내고 $20^{\circ}C$ 보존(保存)에 있어서는 3개(個) 시유(市乳)가 <$10^2$의 내열성균수(耐熱性菌數)를 나타내었다. 6. 초고온살균유(超高溫殺菌乳)의 대장균수(大腸菌數) 검사결과(檢査結果)는 모두 시유(市乳)에 있어서 나타나지 않았다.

• Journal of Electrochemical Science and Technology
• /
• 제10권4호
• /
• pp.424-432
• /
• 2019

Planar BiVO₄ and 3 wt% Mo-doped BiVO₄ (abbreviated as Mo:BiVO₄) film were prepared by the facile spin-coating method on fluorine doped SnO₂(FTO) substrate in the same precursor solution including the Mo precursor in Mo:BiVO₄ film. After annealing at a high temperature of 450℃ for 30 min to improve crystallinity, the films exhibited the monoclinic crystalline phase and nanoporous architecture. Both films showed no remarkably discrepancy in crystalline or morphological properties. To investigate the effect of surface passivation exploring the Al₂O₃ layer, the ultra-thin Al₂O₃ layer with a thickness of approximately 2 nm was deposited on BiVO₄ film using the atomic layer deposition (ALD) method. No distinct morphological modification was observed for all prepared BiVO₄ and Mo:BiVO₄ films. Only slightly reduced nanopores were observed. Although both samples showed some reduction of light absorption in the visible wavelength after coating of Al₂O₃ layer, the Al₂O₃ coated BiVO₄ (Al₂O₃/BiVO₄) film exhibited enhanced photoelectrochemical performance in 0.5 M Na₂SO₄ solution (pH 6.5), having higher photocurrent density (0.91 mA/㎠ at 1.23 V vs. reversible hydrogen electrode (RHE), briefly abbreviated as V_RHE) than BiVO₄ film (0.12 mA/㎠ at 1.23 V_RHE). Moreover, Al₂O₃ coating on the Mo:BiVO₄ film exhibited more enhanced photocurrent density (1.5 mA/㎠ at 1.23 V_RHE) than the Mo:BiVO₄ film (0.86 mA/㎠ at 1.23 V_RHE). To examine the reasons, capacitance measurement and Mott-Schottky analysis were conducted, revealing that the significant degradation of capacitance value was observed in both BiVO₄ film and Al₂O₃/Mo:BiVO₄ film, probably due to degraded capacitance by surface passivation. Furthermore, the flat-band potential (V_FB) was negatively shifted to about 200 mV while the electronic conductivities were enhanced by Al₂O₃ coating in both samples, contributing to the advancement of PEC performance by ultra-thin Al₂O₃ layer.

• 미생물학회지
• /
• 제20권3호
• /
• pp.125-133
• /
• 1982

Mutational experiments were performed to imporve the cellulase productivity of Aspergillus phoenicis KU175, isolated from the southern part of Korea, as a high cellulase producer. By treatment ultra-violet light nad 4-NQO(4-Nitroquinoline-N-Oxide), mutation waas induced, and treatment ultra-violet light and 4-NQO (4-Nitroquinoline-N-Oxide), mutation was induced, and A.phoenicis KU175-115 was finally selected for its highest avicelase production. Avicelase production of the mutant was increased about 2 times compared with those of the wild strain. However, activities of other hydrolytic enzymes, such as amylase, protease and nuclease, of the mutant strain didn't show a marked difference compared with those of the nuclease, of the mutant strain didn't show a marked difference compared with the wild strain, except slight increase in ribonuclease activity and slight decrease in glucoamylase activity. Avicelases from the mutant strain selected were purified from wheat bran culture by successive salting out, followed by dialysis and column chromatography, and their charcteristics were compared with thosw of the wild strain. Avicelase was separated into three peaks in the mutant strain as well as in the case of wild strain. Avicelase II activity of the mutant strain was prominently higher than that of the wild strain, while avicelase I and III activities of those were equivalent. The optimal pH ranges and stability of avicelase II from the mutant strain were pH4-5 and pH3.5-6.0, respectively, as well as in the case of the wild strain. The optimal temperature and thermal stability of avicelase II from the mutant strain were $40{\sim}50^{\circ}C\;and\;20{\sim}55^{\circ}C$, respectively. These results were same as those of the wild strain. By the using of Eadie-Hofastee plot, $K_m\;and\;V_{max}$ of avicelase II from the mutant and the wild strain were calculated to be 2.29mg/ml and $4.84{\mu}g$ reducing sugar as glucose per min equally, from the line fitted to the data by the least square method. Activity of avicelase II from the mutant strain was slightly activated by $Mg^{++}\;but\;inhibited\;by\;Cu^{++}, \;Mn^{++}\;and\;Zn^{++}$, as well as in the case of the wild strain. Therefore, it was concluded that the mutant didn't induce the formation of another avicelase isozyme, or the changes in the properties of avicelase, but induce the changes in the productively of the same avicelase II by the action of regulatory gane.

• Journal of Ginseng Research
• /
• 제42권2호
• /
• pp.149-157
• /
• 2018

Background: Panax notoginseng leaves (PNL) exhibit extensive activities, but few analytical methods have been established to exclusively determine the dammarane triterpene saponins in PNL. Methods: Ultra-performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC/Q-TOF MS) and HPLC-UV methods were developed for the qualitative and quantitative analysis of ginsenosides in PNL, respectively. Results: Extraction conditions, including solvents and extraction methods, were optimized, which showed that ginsenosides Rc and Rb3, the main components of PNL, are transformed to notoginsenosides Fe and Fd, respectively, in the presence of water, by removing a glucose residue from position C-3 via possible enzymatic hydrolysis. A total of 57 saponins were identified in the methanolic extract of PNL by UPLC/Q-TOF MS. Among them, 19 components were unambiguously characterized by their reference substances. Additionally, seven saponins of PNL-ginsenosides Rb1, Rc, Rb2, and Rb3, and notoginsenosides Fc, Fe, and Fd-were quantified using the HPLC-UV method after extraction with methanol. The separation of analytes, particularly the separation of notoginsenoside Fc and ginsenoside Rc, was achieved on a Zorbax ODS C8 column at a temperature of $35^{\circ}C$. This developed HPLC-UV method provides an adequate linearity ($r^2$ > 0.999), repeatability (relative standard deviation, RSD < 2.98%), and inter- and intraday variations (RSD < 4.40%) with recovery (98.7-106.1%) of seven saponins concerned. This validated method was also conducted to determine seven components in 10 batches of PNL. Conclusion: These findings are beneficial to the quality control of PNL and its relevant products.

• 한국세라믹학회지
• /
• 제41권5호
• /
• pp.370-374
• /
• 2004

본 연구에서는 수열합성법으로 SrAl$_2$O$_4$:Eu 형광체 분말을 합성하여 이들의 발광 특성과 장잔광 특성 등에 대해서 고찰하였다. 증류수에 Sr(NO$_3$)$_2$, Al(NO$_3$)$_3$ㆍ9$H_2O$, Eu(NO$_3$)$_3$$.$6$H_2O$ 등의 금속염을 용해시킨 용액을 NH$_4$OH 수용액으로 pH 률 적당히 조절하고 고온고압의 Autoclave 반응용기 내에서 반응시켰다. 이렇게 합성된 분말은 균일한 입도 분포를 나타내었으며, sub-micron 크기의 초미세 분말이었다. 합성된 SrAl$_2$O$_4$:Eu 초미세 분말을 Ar-H$_2$ 가스 환원분위기에서 1100 -140$0^{\circ}C$ 온도로 2시간동안 열처리시켜서 형광 특성을 나타내도록 만들었다. 분말의 여기 및 발광 특성을 측정한 결과, 발광파장을 520 nm 로 고정시켜 측정한 여기스펙트럼은 250 ∼ 450 nm 의 넓은 파장영역에 걸쳐 여기가 일어났고, 발광스펙트럼은 520 nm에서 최대 피크를 나타내었다. 또한 10분간 여기시킨 후 520 nm 파장에 대한 잔광 특성이 1000초 이상 지속되는 우수한 장잔광 특성을 나타내었다. 그 밖에 SEM, XRD를 이용하여 SrAl$_2$O$_4$:Eu 형광체 분말에 대한 미세구조 및 결정구조를 고찰하였다.

• 한국컴퓨터정보학회논문지
• /
• 제27권5호
• /
• pp.1-9
• /
• 2022

사람이나 사물 등의 위치를 알아낼 수 있는 측위기술은 사람의 유동량 측정, 보안, 인원 구조 등 다양한 환경에서 요구되고 사용될 수 있다. 측위를 위해 카메라와 같은 시각 센서기술을 사용하기도 하지만 이는 빛, 온도 등 주변 환경에 민감하며 사생활 노출 문제가 발생할 수 있다. 본 논문에서는 앞서 말한 문제들이 없는 초광대역 (UWB, ultra wideband) 레이더 기술과 머신러닝을 이용하여 벽 뒤 다른 실내공간에 있는 점유자의 수와 위치를 인식하는 연구를 수행하였다. 네 가지 상황 (강의실 내 몇 명이 있는지, 28가지의 위치를 정하고 어느 위치에 있는지, 28가지의 위치 중 한 위치에서 더 세부적인 16가지 위치 중 어느 위치에 있는지, 두 명이 동시에 있는 상황에서 어느 위치에 있는지)에 대해 극단적 랜덤 트리 등 네 가지 알고리즘 별로 모델을 생성하고 그 결과를 비교하였다. 전체적으로 네 가지 알고리즘 모두 좋은 결과를 보여주었으며 머신러닝을 이용해 위치인식 및 위치측정이 가능함을 검증하였다. 또한 oneM2M 표준 플랫폼을 활용하여 서비스 확장 가능성을 고려하였으며 이 기술을 여러 분야에서 활용한다면 더욱 많은 서비스나 제품을 창출할 수 있을 것으로 기대한다.