• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.342-345
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• 2000

Effect of volcanic ash on cell growth of Aspergillus sp. and production of exopolymers by Agrobacterium sp. and Aureobasidium pullualns was investigated. The volcanic ash contained various mineral salts such as $SiO_2$, $Al_2O_3$, CaO, $K_2O$. Maximal cell growth of Aspergillus sp. was obtained when 0.3% volcanic ash was added to medium. Cell growth of Aspergillus sp. increased with higher concentration of volcanic ash in medium. Amount of cell growth with 0.3 % volcanic ash was 6.7 times higher than that without volcanic ash. Volcanic ash also stimulated production of exopolymer as well as cell growth. Production of curdlan with 0.1% volcanic ash was 12.40 g/l whereas that without volcanic ash was 9.15 g/l. Production of pullulan with volcanic ash was also higher than that without volcanic ash.

• Nuclear Engineering and Technology
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• 제46권2호
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• pp.125-146
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• 2014

This review aims to provide a synthesis of the knowledge generated and the lessons learned in roughly 15 years of UMo dispersion fuel R&D in Europe through a series of irradiation experiments. A lot of irradiations were also performed outside of Europe, particularly in the USA, Russia, Canada, Korea and Argentina. In addition, a large number of out-of-pile investigations were done throughout the world, providing support to the understanding of the phenomena governing the UMo behaviour in pile. However, the focus of this article will be on the irradiations and Post-Irradiation Examination (PIE) results obtained in European experiments. The introduction of the article provides a historic overview of the evolution and progress in the high density UMo dispersion fuel development. The ensuing sections then provide further details on the various phases of the development, from the UMo dispersion in a pure Al matrix through the addition of Si to the matrix to address the interaction layer formation and finally to the more advanced solutions to the excessive swelling encountered in various experiments. This review was based only on published results or results that are currently in the process of being published.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.86.2-86.2
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• 2015

Cu2ZnSn(S,Se)4 thin film solar cells have been fabricated using sputtered Cu/Sn/Zn metallic precursors on Mo coated sodalime glass substrate without using a toxic H2Se and H2S atmosphere. Cu/Sn/Zn metallic precursors with various thicknesses were prepared using DC magnetron sputtering process at room temperature. As-deposited metallic precursors were sulfo-selenized inside a graphite box containing S and Se pellets using rapid thermal processing furnace at various sulfur to selenium (S/Se) compositional ratio. Thin film solar cells were fabricated after sulfo-selenization process using a 65 nm CdS buffer, a 40 nm intrinsic ZnO, a 400 nm Al doped ZnO, and Al/Ni top metal contact. Effects of sulfur to selenium (S/Se) compositional ratio on the microstructure, crystallinity, electrical properties, and cell efficiencies have been studied using X-ray diffraction, Raman spectroscopy, field emission scanning electron microscope, I-V measurement system, solar simulator, quantum efficiency measurement system, and time resolved photoluminescence spectrometer. Our fabricated Cu2ZnSn(S,Se)4 thin film solar cell shows the best conversion efficiency of 9.24 % (Voc : 454.6 mV, Jsc : 32.14 mA/cm2, FF : 63.29 %, and active area : 0.433 cm2), which is the highest efficiency among Cu2ZnSn(S,Se)4 thin film solar cells prepared using sputter deposited metallic precursors and without using a toxic H2Se gas. Details about other experimental results will be discussed during the presentation.

• 한국광물학회지
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• 제14권1호
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• pp.39-51
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• 2001

공주군 유구면 일대의 화강암질 편마암의 풍화작용에 따른 원소의 거동과 pH와 이차광물과의 관계를 XRF, ICP-AES, ICP-MS를 이용한 원소분석결과를 통하여 검토하였다. 이 지역의 암석은 pH6 내외의 산성환경, 침철석, 아나타제와 같은 다양한 이차광물을 생성하면서 심각한 화학조성의 변화를 초래했다. 주원소의 화학조성을 이용한 풍화지수는 토양층에서 79~88로 모암 중의 사장석이 용해되고 흑운모가 변질되어 캐올리광물의 생성이 활발한 방향으로 풍화작용이 진행되었다. 지표층으로 가면서 Al에 대한 주 원소의 거동은 Si, Ca, Na, K, P가 감소하고 Fe, Ti, Mn이 증가하는 경향을 보이며 pH가 낮은 풍화단면에서 주 원소의 변화량이 더 크다. 이 풍화대에서 Mg은 거의 일정하다. Li, As 모든 전이원소는 pH가 감소함에 따라 증가하며 특히 이들 원소는 Fe의 함량과 비례해서 증가해 침철석과 공침하였거나 표면에 흡착되어 있는 것으로 보인다. Ga은 Fe와 비례하기는 하지만 변화량은 전 풍화단면에서 일정하다. Zr, Mo, Sn, Cd은 pH에 변화에 상관없이 일정한 반면에 Rb, Sr, Ba, Y, Pb, Th, U 등은 감소하는 경향을 보인다. 특히 Rb 과 Sr은 Ca에 비례해서 감소한다. 희토류원소는 전 풍화단면에서 감소하는 경향을 보이는데 $Al_2$$O_3$에 대한 상대적인 변화량을 보면 경희토류원소는 사프롤라이트(saprolite)하부와 상부에서 부화되어 있고 중부 사프롤라이트와 토양층에서 감소하는 반면에 중희토류원소는 사프롤라이트 하부와 상부에서 감소하고 중부사프롤라이트 및 토양층에서 부화되는 경향을 보인다. 전반적으로 희토류원소의 원자번호가 클수록 손실율이 커진다. 이 풍화단면에서 원소의 거동은 각 풍화층의 pH와 생성된 이차광물의 조성에 지배를 받았다.

• 대한치과보철학회지
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• 제35권1호
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• pp.144-164
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• 1997

The purpose of this study were to investigate the chemical composition, mean particle size, linear thermal expansion coefficient and metal-bonding strength of the regular opaque powder and core powder. In this study, 4 types of ceramic powders, namely Duceram Jacket Opaque powder, Duceram Opaque powder, Vita Hi-Ceram powder, Vita VMK Paint On-88 powder were used. Chemical composition was evaluated by EDS(Energy Dispersive X-ray Spectrophotometer, Oxford QX-2000, England), particle size was measured by MALVERN Instruments(MALVERN Instruments SB. OC., U.S.A.. ad linear thermal expansion coefficient was measured by dilatometer(Motoyama, Japan). Bond strength was measured by the Universal tsting machine(Istron Co., Ltd., U.S.A.). The Results were as follows : 1. Through recognition of the relative difference in chemical composition between the core powder and the regular opaque powder, the difference in the proportion of $Al_2O_3$ in each type of material is demonstrated ; Duceram Jaket Opaque powder : 30.16%, Duceram Opaque powder : 16.60%, Vita Hi-Ceram : 63.64%, Vita VMK Paint-On 88 : 16.16%. 2. There was no significant difference in the proportion of metal-bonding materials between the core powder and the regular opaque powder. 3. In the regular opaque powder, alkaline materials were incoporated in order to increase the coefficient of thermal expansion. 4. In the particle size analysis, there was no significant difference in mean particle size or in the particle size distribution between the core powder and the regular opaque powder. 5. In the thermal expansion test for temperature range of $25-600^{\circ}C$, the regular opaque powder had higher coefficient of thermal expansion than that of core powder. 6. In the 4 point flexural bending test, there was no statistically significant difference in the mean bond strength between the core powder and the opaque powder among the Duceram products.

• 자원환경지질
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• 제30권6호
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• pp.553-566
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• 1997

Origin, behavior and enrichment of environmental toxic elements from the Deokpyeong area were investigated on the basis of major, trace and rare earth element geochemistry. Coaly metapelites of the Deokpyeong area are subdivided into grey phyllite, dark grey phyllite, coaly slate and black slate, which are interbedded along the Ogcheon Supergroup. The coaly slate had been mined for coal, but mining is closed. The coaly and black slates are lower contents of $SiO_2$ and $Al_2O_3$, and higher contents of LOI, CaO, $Na_2O$ and BaO as compared with the phyllitic rocks. Rare earth elements are highly enriched in the coaly and black slate. Average compositions (ppm) of minor and/or environmental toxic elements in the coaly and black slate are revealed as As=127, Ba=30,163, Cd=18, Cr=740, Cu=84, Mo=378, Pb=43, Sb=12, Se=44, U=144, V=8,147 and Zn=292, which are extremely high concentrations than those in the NASC compositions. Major elements (average enrichment index; 5.34) in the coaly metapelites are mostly depleted, excepting $P_2O_5$ and BaO, normalized by NASC. Rare earth elements (average enrichment index; 1.48) are enriched in the coaly slate. On the basis of NASC, minor and/or environmental toxic elements in the coaly metapelites were strongly enriched of all the elements with the exception of Co, Cs, Ni and Sr. Average enrichment index of trace elements in coaly metapelite is 31.51 (coaly slate; 51.94 and black slate; 15.46). Especially, enrichment index of potentially toxic elements (As, Ba, Cr, Cu, Mo, Ni, Sb, Se, U, V and Zn) of the rock is 46.10 (grey phyllite; 7.15, dark grey phyllite; 4.77, coaly slate; 88.96 and black slate; 22.11). These coal formations were deposited in basin of boundary between terrestrial and marine environments deduced to carbon, sulfur (C/S=2.2 to 275.7), trace and rare earth elements characteristics. Irregular behavior and dispersion between major, minor and rare earth elements of those metapelites indicates a variable source materials, incomplete mixing of differential source and/or reequilibrium of diagenesis and metamorphism.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2005년도 춘계 학술대회
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• pp.121-128
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• 2005

방사성 폐기물의 핵종 재고량 평가에 필요한 정량분석을 위하여 다양한 매질의 방사성 폐기물 시료로부터 $^{99}Tc,\;^{94}Nb,\;^{55}Fe,\;^{90}Sr$ 및 $^{59}Ni(^{63}Ni)$의 선택적 분리에 관한 연구가 수행되고있다. 방사성 폐기물 용해용액의 화학조성을 모사하여 만든 모의 방사성 폐기물 용해용액을 사용하여 음이온교환수지법과 Sr-Spec 추출 크로마토그래피로 Re ($^{99}Tc$ 대용원소), Nb, Fe 및 Sr을 분리해 낸 후 Ni과 함께 회수되는 Ce, Ca, Mg, Al, Cr, Ti, Mn 및 Cu와 Ni의 분리 거동을 Ni-Spec 추출크로마토그래피와 양이온교환수지법으로 조사하였다. 공존원소들로부터 Ni의 선택적 분리와 기체비례계수법에 의한 방사능 측정에 적합한 radionuclide source를 만들기 위하여 공존원소들에 대한 가리움제로 ammonium citrate 및 tartaric acid를 사용하는 dimethylglyoxime 침전법의 적용에 관하여 기술하였다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.54-56
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• 2005

Ultrasonic soldering using of Si-wafer to FR-4 PCB atroom temperature was investigated. Sn3.5Ag foil rolled $100{\mu}m$ was used for solder. The UBM of Si-die was Cu/ Ni/ Al from top to bottom and its thickness was $0.4{\mu}m$, $0.4{\mu}m$, $0.3{\mu}m$ respectively. Pad on FR-4 PCB comprised of Au/ Ni/ Cu from top to bottom and its thickness was $0.05{\mu}m$, $5{\mu}m$, $18{\mu}m$ respectively. The ultrasonic soldering time was changed from 0.5sec to 3.0sec and its power 1400W. As experimental result, reliable bond joint by ultrasonic at room temperature was obtained. The shear strength increased with soldering time up to 2.5 sec. That means at 2.5sec, the shear strength showed maximum rate of 65.23N. The strength decreased to 33.90N at 3.0 sec because the cracks generated along the intermetallic compound between Si-wafer and Sn-3.5mass%Ag solder. intermetallic compound produced by ultrasonic between the solder and the Si-die was $(Cu, Ni)_{6}Sn_{5}$ and the intermetallic compound between solder and pad on FR-4 was $(Ni, Cu)_{3}Sn_{4}$.

• 자원환경지질
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• 제22권1호
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• pp.35-63
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• 1989

구룡산(九龍山)(또는 옥천(沃川)) 함(含)우라늄 흑연질점판암(黑鉛質粘板岩)은 옥천대(沃川帶) 서북부(西北部)에 따라 증상(層狀) 또는 부딘상(狀)으로 90km이상(以上) 연장(延長) 분포(分布)한다. 함(含)우라늄점판암(粘板岩)의 오토레디오그라프에 나타나는 퇴적(堆積), 속성(續成), 변성구조(變成構造)는 우라늄과 동시퇴적물(同時堆積物)로서 속성작용과정(續成作用過程)에서 전혀 이동(移動)하지 않고 황성변성(廣域變成) 초기(初期)에 제자리에서 미립(微粒)우라니나이트로 재결정(再結晶)하였음을 보여준다. 동시(同時)에 유기물(有機物)은 미세환장흑연(微細環狀黑鉛)으로 되었다. 라미나구조(構造)의 발달(發達)과 평균(平均) 19.64% C, 2.32% S의 함유(含有)는 함(含)우라늄흑니(黑泥) 퇴적(堆積)의 일반조건(一般條件)으로서의 극(極)히 낮은 퇴적화(堆積比), 고유기물함유(高有機物含有), 염기성황경등을 충족(充足)하였으며 Th/U가 0.07로서 해수원(海水源)임을 뜻한다. 지역별(地域別) CaO, $P_2O_5$의 평균치(平均値)가 매우좁은 범위(範圍)의 일정치(一定値)이며 높은 CaO 평균치(平均値)를 나타내어 전퇴적(全堆積)분지를 통(通)하여 동일(同一) pH(7.8-8.0)조건(條件)의 환경(環境)에서 퇴적(堆積)하였음을 나타낸다. 함(含)우라늄점판암(粘板岩)은 같은 성인(成因)의 타산장(他産狀)에 비(比)하여 미량원소(微量元素) 부화도(富化度)가 매우 높다. 고부화(高富化)의 중요(重要)한 원인(原因)으로서 미량원소(微量元素)의 소스(source)인 해수(海水)의 주기적(週期的) 교체(交替)가 요구(要求)되는데 사이크릭퇴적구조(堆積構造)는 그러한 현상(現象)을 뒷받침하여 준다. 흑니(黑泥)의 성인별(成因別) 구성광물(構成鑛物)과 원소(元素)의 수반관계(隨伴關係)에서 쇄설성광물(鑛物)에는 Si, Al, K, Na, Ti, Zr, Th, Be, B, Li, 유기물(有機物)후락숀에, U, Ni, Cu, Co, Zn, Ag, Mo, Pb, Sn, Cd, S, Fe, V, Cr, Y, 탄산염광물(炭酸鹽鑛物)에 Ca, Mg, Mn, P, Ba가 높은 상관(相關)을 나타낸다. 유기물(有機物)의 우라늄고정심전능력(固定沈澱能力)에 있어 사프로페릭(Sapropelic)형(型)보다 휴믹(Humic)형(型)에서 더 높다. 육성식물(陸性植物)의 분해물(分解物)인 휴무스(Humus)는 고대성(古生代) 중기(中期)에 출현(出現)한다. 우라늄 함유(含有) 흑니(黑泥)는 이 시대(時代)의 형성물(形成物)로서 이런 형(型)의 광상(鑛床)은 생물상(生物相)의 진화(進化)에 규제(規制)된 광화작용(鑛化作用)의 산물(産物)이다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.5-5
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• 2011

The research and development of hybrid electric vehicle (HEV), plug-in hybrid electric vehicle (PHEV) and electric vehicle (EV) are intensified due to the energy crisis and environmental concerns. In order to meet the challenging requirements of powering HEV, PHEV and EV, the current lithium battery technology needs to be significantly improved in terms of the cost, safety, power and energy density, as well as the calendar and cycle life. One new technology being developed is the utilization of composite cathode by mixing two different types of insertion compounds [e.g., spinel $LiMn_2O_4$ and layered $LiMO_2$ (M=Ni, Co, and Mn)]. Recently, some studies on mixing two different types of cathode materials to make a composite cathode have been reported, which were aimed at reducing cost and improving self-discharge. Numata et al. reported that when stored in a sealed can together with electrolyte at $80^{\circ}C$ for 10 days, the concentrations of both HF and $Mn^{2+}$ were lower in the can containing $LiMn_2O_4$ blended with $LiNi_{0.8}Co_{0.2}O_2$ than that containing $LiMn_2O_4$ only. That reports clearly showed that this blending technique can prevent the decline in capacity caused by cycling or storage at elevated temperatures. However, not much work has been reported on the charge-discharge characteristics and related structural phase transitions for these composite cathodes. In this presentation, we will report our in situ x-ray diffraction studies on this mixed composite cathode material during charge-discharge cycling. The mixed cathodes were incorporated into in situ XRD cells with a Li foil anode, a Celgard separator, and a 1M $LiPF_6$ electrolyte in a 1 : 1 EC : DMC solvent (LP 30 from EM Industries, Inc.). For in situ XRD cell, Mylar windows were used as has been described in detail elsewhere. All of these in situ XRD spectra were collected on beam line X18A at National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory using two different detectors. One is a conventional scintillation detector with data collection at 0.02 degree in two theta angle for each step. The other is a wide angle position sensitive detector (PSD). The wavelengths used were 1.1950 ${\AA}$ for the scintillation detector and 0.9999 A for the PSD. The newly installed PSD at beam line X18A of NSLS can collect XRD patterns as short as a few minutes covering $90^{\circ}$ of two theta angles simultaneously with good signal to noise ratio. It significantly reduced the data collection time for each scan, giving us a great advantage in studying the phase transition in real time. The two theta angles of all the XRD spectra presented in this paper have been recalculated and converted to corresponding angles for ${\lambda}=1.54\;{\AA}$, which is the wavelength of conventional x-ray tube source with Cu-$k{\alpha}$ radiation, for easy comparison with data in other literatures. The structural changes of the composite cathode made by mixing spinel $LiMn_2O_4$ and layered $Li-Ni_{1/3}Co_{1/3}Mn_{1/3}O_2$ in 1 : 1 wt% in both Li-half and Li-ion cells during charge/discharge are studied by in situ XRD. During the first charge up to ~5.2 V vs. $Li/Li^+$, the in situ XRD spectra for the composite cathode in the Li-half cell track the structural changes of each component. At the early stage of charge, the lithium extraction takes place in the $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ component only. When the cell voltage reaches at ~4.0 V vs. $Li/Li^+$, lithium extraction from the spinel $LiMn_2O_4$ component starts and becomes the major contributor for the cell capacity due to the higher rate capability of $LiMn_2O_4$. When the voltage passed 4.3 V, the major structural changes are from the $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ component, while the $LiMn_2O_4$ component is almost unchanged. In the Li-ion cell using a MCMB anode and a composite cathode cycled between 2.5 V and 4.2 V, the structural changes are dominated by the spinel $LiMn_2O_4$ component, with much less changes in the layered $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ component, comparing with the Li-half cell results. These results give us valuable information about the structural changes relating to the contributions of each individual component to the cell capacity at certain charge/discharge state, which are helpful in designing and optimizing the composite cathode using spinel- and layered-type materials for Li-ion battery research. More detailed discussion will be presented at the meeting.