• 자원환경지질
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• 제34권2호
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• pp.193-204
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• 2001

1997년 집중호우 때 지반 침하와 융기 현상이 발생했던 안동시 위리 지역의 지하구조와 사면활동의 기구가 된 단층대를 규명하기 위해 전기비저항 수직 및 쌍극자탐사, 탄성파굴절법 및 반사법탐사를 실시하였다. 사면 변형의 가장 주된 원인으로 알려진 점토층은 탐사 결과 $100{\Omega}{\cdot}m$ 이하의 전기비저항, 400m/s 이하의 탄성파속도로 특징되며, 사면침하와 관련된 북북서 단층은 약 $18^{\circ}$의 경사로 비교적 완만하게 나타나고, 지반 융기와 관련된 도로 인근의 북북동 단층은 거의 수직으로 나타난다. 사면활동 당시 사면에서 일어난 침하 현상은 북북서 단충면을 따라 점토가 거동하며 생긴 반면 도로 지반의 융기는 북북동 수직 단층을 통하여 점토가 올라 온 현상으로 해석된다.

• Electronic Materials Letters
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• 제14권6호
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• pp.700-711
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• 2018

CdS synthesized by the chemical bath method at $70^{\circ}C$, has been used as an electron transport layer in the planar structure of the perovskite solar cells. A two-step spin process produced a mixed halide perovskite of $CH_3NH_3PbI_{3-x}Cl_x$ and a mixture of $PbCl_2$ and $PbI_2$ was deposited on CdS, followed by a sub-sequential reaction with MAI ($CH_3NH_3I$). The added $PbCl_2$ to $PbI_2$ in the first spin-step affected the structure, orientation, and shape of lead halides, which varied depending on the content of Cl. A small amount of Cl enhanced the surface morphology and the preferred orientation of $PbI_2$, which led to large and uniform grains of perovskite thin films. In contrast, the high content of Cl produces a new phase PbICl in addition to $PbI_2$, which leads to the small and highly uniform grains of perovskites. An improved surface coverage of perovskite films with the large and uniform grains maximized the performance of perovskite solar cells at 0.1 molar ratio of $PbCl_2$ to $PbI_2$. The depth profiling of elements in both lead halide films and mixed halide perovskite films were measured by Rutherford backscattering spectroscopy, revealing the distribution of chlorine along with the thickness, and providing the basis for the mechanism for enhanced preferred orientation of lead halide and the microstructure of perovskites.

• 대한금속재료학회지
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• 제46권3호
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• pp.159-168
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• 2008

Thermally-evaporated 10 nm-Ni/1 nm-Ru/(30 nm or 70 nm-poly)Si structures were fabricated in order to investigate the thermal stability of Ru-inserted nickel monosilicide. The silicide samples underwent rapid thermal anne aling at $300{\sim}1,100^{\circ}C$ for 40 seconds. Silicides suitable for the salicide process were formed on the top of the single crystal and polycrystalline silicon substrates mimicking actives and gates. The sheet resistance was measured using a four-point probe. High resolution X-ray diffraction and Auger depth profiling were used for phase and chemical composition analysis, respectively. Transmission electron microscope and scanning probe microscope(SPM) were used to determine the cross-sectional structure and surface roughness. The silicide, which formed on single crystal silicon and 30 nm polysilicon substrate, could defer the transformation of $Ni_2Si $i and $NiSi_2 $, and was stable at temperatures up to $1,100^{\circ}C$ and $1,100^{\circ}C$, respectively. Regarding microstructure, the nano-size NiSi preferred phase was observed on single crystalline Si substrate, and agglomerate phase was shown on 30 nm-thick polycrystalline Si substrate, respectively. The silicide, formed on 70 nm polysilicon substrate, showed high resistance at temperatures >$700^{\circ}C$ caused by mixed microstructure. Through SPM analysis, we confirmed that the surface roughness increased abruptly on single crystal Si substrate while not changed on polycrystalline substrate. The Ru-inserted nickel monosilicide could maintain a low resistance in wide temperature range and is considered suitable for the nano-thick silicide process.

• 지구물리와물리탐사
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• 제13권1호
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• pp.24-30
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• 2010

본 연구는 시간차 탄성파 탐사에 대한 천부지하구조의 영향을 분석하기 위해 반복적인 수치모형실험을 이용하였다. 수치 실험의 목적은 Otway 분지에 있는 Naylor 지역에서 $CO_2$ 격리를 목적으로 수행 된 현장 실험에서 관찰된 주요한 산란파들을 재생성하는 것이다. 특히, 수포화도를 변화시켜 가면서 상부토양과 심부의 주름진 점토/석회암 경계면의 탄성 성질들의 변화를 관찰하였다. 이러한 실험을 통해서 건기 빛 우기 계절에 행해진 측정치를 모사하였고, 계절의 변화가 탄성파 측정에 미치는 영향을 비반복성 관점에서 평가하였다. 이 영향들에 대한 정량화와 각각의 기여도를 측정하기 위해서 탄성파 파동방정식을 이용한 수치모델링이 수행되었다. 수치모델링 결과는 천부의 점토/석회암의 주름진 경계면에서의 상대적으로 간단한 분산 효과등이 시간차 탐사에 대한 상당한 영향을 미침을 보여주었다. 또한, 상부 토양에서의 포화도의 변화는 심지어 심부의 주름진 경계면보다도 더 탄성파 신호에 잠재적으로 영향을 미칠 수 있다. 현장에서 측정된 반복된 (시간차) 2차원 탄성파탐사 자료들 사이의 정규화원 RMS(Root-mean-square) 차이와 수치적으로 계산된 차이와의 전체적인 일치는 더 많은 연구가 필요함을 알 수 있다. 향후 진행될 연구는 micro VSP 배영과 매우 조밀한 굴절법 탐사를 이용해서 풍화 지역의 탄성 성질을 현장에서 측정하는 것이다. 본 연구의 결과는 중풍이냐 호주와 같이 카르스트 지형으로 생산에 어려움이 따르는 지역의 석유 생산 영상화와 같은 $CO_2$ 지중격리와 상관이 없는 분야에도 효과가 있을 것이다.

• 지구물리와물리탐사
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• 제12권3호
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• pp.255-262
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• 2009

가스하이드레이트 개발 시 중요한 요소 중의 하나인 가스하이드레이트 부존층의 정확한 심도를 얻기 위해서는 일반적으로 고해상도 정보를 주는 VSP 탐사가 많이 수행되어왔다. 본 연구에서는 가스하이드레이트 부존지역인 울릉분지 지역의 UBGH09 시추공에서 국내 최초로 삼성분 지오폰을 사용하여 획득한 제로오프셋 VSP 탐사자료로부터 구간속도를 추출하고 corridor 중합단면도를 생성하여 지표탄성파탐사 자료와 비교해 보았다. 먼저 Phase rotation을 통하여 삼성분 지오폰으로 기록된 신호들이 실제 수직 및 두 개의 수평성분 자료들이 되도록 변환 시키고, 파동장 분리과정을 통하여 직접파와 반사파를 분리하였다. 제로오프셋 VSP 자료의 직접파로부터 추출한 구간속도를 음파검층의 구간속도와 비교한 결과 두 구간속도 모두 비슷한 양상을 나타냈다. BSR 상부의 하이드레이트 층에서는 빠른 속도를 보이고 BSR 하부에서 속도가 급격히 떨어지는 것으로 보아 BSR 하부에 유리가스가 집적되어 있는 것으로 보인다. 제로오프셋 VSP 반사파 자료로부터 corridor 중합단면도를 생성하여 지표탄성파탐사의 CMP 중합단면도와 비교한 결과 대부분의 반사이벤트들이 잘 부합하였으며, phase rotation을 적용한 결과가 phase rotation을 적용하지 않았을 경우보다 더 잘 부합하였다.또한 transverse 성분을 이용하여 만든 corridor 중합단면도와 지표탄성파 CMP 중합단면도를 비교한 결과 지표탄성파 CMP 중합 단면도 내의 모오드 변환된 PS 반사파들을 확인할 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제14권6호
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• pp.1239-1248
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• 2004

The methylotrophic yeast Hansenula polymorpha has been extensively studied as a model organism for methanol metabolism and peroxisome biogenesis. Recently, this yeast has also attracted attention as a promising host organism for recombinant protein production. Here, we describe the fabrication and evaluation of a DNA chip spotted with 382 open reading frames (ORFs) of H. polymorpha. Each ORF was PCR-amplified using gene-specific primer sets, of which the forward primers had 5'-aminolink. The PCR products were printed in duplicate onto the aldehyde-coated slide glasses to link only the coding strands to the surface of the slide via covalent coupling between amine and aldehyde groups. With the partial genome DNA chip, we compared efficiency of direct and indirect cDNA target labeling methods, and found that the indirect method, using fluorescent-labeled dendrimers, generated a higher hybridization signal-to-noise ratio than the direct method, using cDNA targets labeled by incorporation of fluorescence-labeled nucIeotides during reverse transcription. In addition, to assess the quality of this DNA chip, we analyzed the expression profiles of H. polymorpha cells grown on different carbon sources, such as glucose and methanol, and also those of cells treated with the superoxide­generating drug, menadione. The profiles obtained showed a high-level induction of a set of ORFs involved in methanol metabolism and oxidative stress response in the presence of methanol and menadione, respectively. The results demonstrate the sensitivity and reliability of our arrays to analyze global gene expression changes of H. polymorpha under defined environmental conditions.

• 한국작물학회지
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• 제58권1호
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• pp.50-56
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• 2013

SELDI-TOF MS를 활용한 저분자 펩타이드 분석을 위해서는 분석시료에 대한 최적화 분석조건을 확립하는 것이 필수적으로 선행되어야 한다. 본 연구는 수수 종자 내 존재하는 10 kDa 이하의 저분자 펩타이드를 프로파일링하기 위하여 활용된 SELDI-TOF MS의 최적화 분석조건을 확립하는데 있다. 분석조건은 (1) 프로테인 칩: CM10(weak cation exchanger), Q10(strong anion exchanger), (2) 바인딩 버퍼의 희석배수: 1/2, 1/5, 1/10, 1/20, 1/50, 1/100, 1/200, (3) Q10의 바인딩 버퍼 강도: 10 mM, 100 mM, (4) 단백질 추출버퍼: sodium borate, sodium borate + acetone, phenol, TCA 버퍼로 하였다. 1. 바인딩 버퍼의 희석배수는 CM10과 Q10 모두 1/20과 1/50이 최적화로 나타났다. 2. Q10의 바인딩 버퍼 강도는 농도가 약한 10 mM에서 더 많은 피크가 검출되었다. 3. SELDI-TOF MS 분석에 적합한 수수 종자단백질 추출 버퍼로는 2~10 kDa 범위에서는 sodium borate 버퍼와 10~20 kDa 범위에서는 phenol 버퍼로 분석되었다.

• Bulletin of the Korean Chemical Society
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• 제24권11호
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• pp.1659-1663
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• 2003

$Al_2O_3$ thin films were grown on H-terminated Si(001) substrates using dimethylaluminum isopropoxide [DMAl: $(CH_3)_2AlOCH(CH_3)_2$], as a new Al precursor, and water by atomic layer deposition (ALD). The selflimiting ALD process by alternate surface reactions of DMAI and $H_2O$ was confirmed from measured thicknesses of the aluminum oxide films as functions of the DMAI pulse time and the number of DMAI-$H_2O$ cycles. Under optimal reaction conditions, a growth rate of ~1.06 ${\AA}$ per ALD cycle was achieved at the substrate temperature of $150\;^{\circ}C$. From a mass spectrometric study of the DMAI-$D_2O$ ALD process, it was determined that the overall binary reaction for the deposition of $Al_2O_3\;[2\;(CH_3)_2AlOCH(CH_3)_2\;+\;3\;H_2O\;{\rightarrow}\;Al_2O_3\;+\;4\;CH_4\;+\;2\;HOCH(CH_3)_2]$can be separated into the following two half-reactions: where the asterisks designate the surface species. Growth of stoichiometric $Al_2O_3$ thin films with carbon incorporation less than 1.5 atomic % was confirmed by depth profiling Auger electron spectroscopy. Atomic force microscopy images show atomically flat and uniform surfaces. X-ray photoelectron spectroscopy and cross-sectional high resolution transmission electron microscopy of an $Al_2O_3$ film indicate that there is no distinguishable interfacial Si oxide layer except that a very thin layer of aluminum silicate may have been formed between the $Al_2O_3$ film and the Si substrate. C-V measurements of an $Al_2O_3$ film showed capacitance values comparable to previously reported values.

• 비파괴검사학회지
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• 제31권5호
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• pp.543-551
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• 2011

Steam generator tubes for nuclear power plants contain the local shape transitions on their inner or outer surface such as dent, bulge, over-expansion, eccentricity, deflection, and so on by the application of physical force during the tube manufacturing and steam generator assembling and by the sludge (that is, corrosion products) produced during the plant operation. The structural integrity of tubes will be degraded by generating the corrosive crack at that location. The profilometry using the traditional bobbin probes which are currently applied for measuring the profile change of tubes gives us basic information such as axial locations and average magnitudes of deformations. However, the three-dimensional quantitative evaluation on circumferential locations, distributional angle, and size of deformations will have to be conducted to understand the effects of residual stresses increased by local deformations on corrosive cracking of tubes. Steam generator tubes of Korean standard nuclear power plants expanded within their tube-sheets by the explosive expansion method and suffered from corrosive cracks in the early stage of power operation. Thus, local deformations of steam generator tubes at the top of tube-sheet were measured with an advanced rotating probe and a laser profiling system for the two cases where the tubes expanded by the explosive expansion method and hydraulic expansion. Also, the trends of eccentricity, deflection, and over-expansion of tubes were evaluated. The advanced eddy current profilometry was confirmed to provide accurate information of local deformations compared with laser profilometry.

• Environmental Analysis Health and Toxicology
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• 제30권
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• pp.7.1-7.7
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• 2015

Objectives The widely promising applications of graphene nanomaterials raise considerable concerns regarding their environmental and human health risk assessment. The aim of the current study was to evaluate the toxicity profiling of graphene family nanano-materials (GFNs) in alternative in vitro and in vivo toxicity testing models. Methods The GFNs used in this study are graphene nanoplatelets ([GNPs]-pristine, carboxylate [COOH] and amide [$NH_2$]) and graphene oxides (single layer [SLGO] and few layers [FLGO]). The human bronchial epithelial cells (Beas2B cells) as in vitro system and the nematode Caenorhabditis elegans as in vivo system were used to profile the toxicity response of GFNs. Cytotoxicity assays, colony formation assay for cellular toxicity and reproduction potentiality in C. elegans were used as end points to evaluate the GFNs' toxicity. Results In general, GNPs exhibited higher toxicity than GOs in Beas2B cells, and among the GNPs the order of toxicity was pristine > $NH_2$ > COOH. Although the order of toxicity of the GNPs was maintained in C. elegans reproductive toxicity, but GOs were found to be more toxic in the worms than GNPs. In both systems, SLGO exhibited profoundly greater dose dependency than FLGO. The possible reason of their differential toxicity lay in their distinctive physicochemical characteristics and agglomeration behavior in the exposure media. Conclusions The present study revealed that the toxicity of GFNs is dependent on the graphene nanomaterial's physical forms, surface functionalizations, number of layers, dose, time of exposure and obviously, on the alternative model systems used for toxicity assessment.