• 대한전자공학회논문지
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• 제26권6호
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• pp.30-37
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• 1989

Silane($SiH_4$), methane($CH_4$), diborane(B_2H_6)그리고 phosphine($PH_3$)을 이용하여 rf글로방전분해법으로 PIN형 a-SiC:H/a-Si:H 이종접합 태양전지를 제작하였다. $SnO_2/ITO$층 형성치 태양전지의 효율은 ITO 투명전극만의 경우보다 1.5% 향상되었다. 제작조건은 P층의 경우 $CH_4/SiH_4$의 비를 5로 하고 두께는 $100{\AA}$이었다. I층은 P층위에 증착하였으나 진성이 아니고 N형에 가깝다. 이 I층을 진성으로 바꾸기 위해서 0.3ppm의 $B_2H_6$를 $SiH_4$에 혼합하여 5000${\AA}$증착했다. 또한 N층은 $PH_4/SiH_4$의 비를 $10^{-2}$로 하여 $400{\AA}$ 증착시켰다. 그 결과 입사강도가 15mW/$cm^2$일 때 개방전압 $V_{oc}=O'$단락전류밀도 $J_{sc=14.6mA/cm^2}$, 충진율 FF=58.2%, 그리고 효율 ${eta}=8.0%$를 나타내었다. 빛의 반사에 의한 손실을 감소시키기 위하여 $MgF_2$를 유리기판위에 도포하였다. 이에 의한 효율은 0.5% 향상되어 전체적인 효율은 8.5%였다.

• Transactions on Electrical and Electronic Materials
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• 제12권6호
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• pp.267-270
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• 2011

In the process of inkjet-printed zinc tin oxide thin-film transistor, the effect of metallic interlayer underneath of source and drain electrode was investigated. The reason for the improved electrical properties with thin molybdenum oxide ($MoO_3$) layer was due to the chemically intermixed state of metallic interlayer, aluminum source and drain, and oxide semiconductor together. The atomic configuration of three Mo $3d_3$ and $3d_5$ doublets, three different Al 2p core levels, two Sn $3d_5$, and four different types of oxygen O 1s in the interfaces among those layers was confirmed by X-ray photospectroscopy.

• 생약학회지
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• 제50권4호
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• pp.245-252
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• 2019

This study was initially explored to procure biomaterials capable of inhibiting cancer cell growth from nine Persicaria species (Polygonaceae). The extract of P. nepalensis that was selected from the initial screenings was further fractionated to identify bioactive compounds. The ethyl acetate (EtOAc) fraction was shown to be the most active in the inhibition of cell growth against six cancer cell lines (IC₅₀ value of 3.77-12.87 ㎍/ml). Phytochemical study led to the isolation of two galactolipids of 1,2-di-O-linolenoyl-3-O-β-D-galactospyranosyl-sn-glycerol (1) and 1-O-linolenoyl-3-O-β-D-galactospyranosyl-sn-glycerol (2) from the hexane fraction and three phenylpropanoyl sucroses of lapathoside A (3), vanicoside B (4) and lapathoside C (5) from the EtOAc fraction. These isolated compounds have not been reported from this plant. Compounds 3 and 4 exhibited the effective growth inhibition against a panel of cancer cell lines (IC₅₀ value of 6.90-18.09 μM). In addition, the anti-inflammatory activity was evaluated to determine lipopolysaccharide (LPS)-induced nitric oxide (NO) formation in RAW264.7 mouse macrophage cells. The EtOAc fraction (IC₅₀; 34.14 ㎍/ml) and its constituents, 3 (8.55 μM) and 4 (7.83 μM) were shown to be effective in the inhibition of LPS-induced NO production. Therefore, compounds 3 and 4 were considered to be active constituents for anti-inflammatory and antitumor activity from P. nepalensis.

• Nuclear Engineering and Technology
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• 제12권1호
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• pp.19-28
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• 1980

파이로포스페이트의 $^{99m}$ Tc즉석표지 방법에 관하여 연구하였다. pH 3.5-5.5에서 냉동건조 상태의 파이로포스 페이트와 SnCl$_2$ 혼합물에 $Na^{99m}$ TcO$_4$ 용액을 가하여 녹임으로써 대략 90%의 표지수율을 얻었다. 표지생성물의 순도와 수율은 85% 메탄올과 0.85% NaCl 용액을 전개용매로하는 2차원 종이 크로마토그래피로 검토하는 한편 생쥐를 실험동물로 하여 생성착물의 생체내 분포 실험도 실시 하였다. 일반적으로 $^{99m}$ Tc (VII)의 환원제인 SnCl$_2$를 적은량 쓸수록 표지 수율이 좋았으며 파이로포스페이트와 SnCl$_2$의몰 비율은 10 : 1~50 : 1로 충분하였다. 환원된 미결합 $^{99m}$ Tc의 양이 많은 생성물을 생쥐체내에투여 할수록 간에 집적되는 방사능 양치 증가하는 것으로 보아 골격조영술에서 잘못된 영상을 얻게되는 원인은 환원된 미결합 $^{99m}$ Tc가 콜로이드 상태의 산화된 Sn 생성물에 흡착되어 일어 나는 것으로 생각되었다. 생성착물의 뼈와 간에 대한 분포비율은 투여후 60분 정도에서 최고 35 : 1이었으며, 파이로젠 시험결과도 양호함으로 생성착물은 골격질환의 연구나 진단목적에 적합함을 알수 있었다.

• 자원환경지질
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• 제22권4호
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• pp.327-339
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• 1989

상동지역(上東地域), 순경(順鏡) 함광석(含鑛石) 페그마타이트에서는 석석(錫石)을 비롯하여 탄탈라이트-콜롬바이트, 그리고 함(含)Ta-금홍석(金紅石) 등(等)이 산출(産出)된다. 석석(錫石)은 산포상(散布狀)의 미정질(微晶質)에서부터 거정질(巨晶質)에 이르기까지 다양(多樣)하며, 일반적(一般的)으로 탄탈라이트-콜롬바이트, 함(含)Ta-금홍석(金紅石)과 공존(共存)하고 있다. 탄탈라이트-콜롬바이트는 미세맥(微細脈) 혹은 용리상능(溶離狀能)로서 석석결정(錫石結晶)에 배태(胚胎)되며 간혹 독립광물(獨立鑛物)로서 석영(石英)에 수반(隨伴)되는 경우가 있다. 함(含)Ta-금홍석(金紅石)은 상기(上記)한 광물(鑛物) 중 최후기상(最後期相)으로서 석영(石英)을 수반(隨伴)하는 세맥상(細脈狀)으로 산출(産出)된다. 석석(錫石)에서 ${\Sigma}Ta^{+5}$, $Nb^{+4}$, $Ti^{+4}$ 및 Fe*은 $Sn^{+4}$과 부(負)의 상관관계(相關關係)로 치환(置換)에 전적(全的)으로 관계(關係)하고 있으며, 0.01-0.15mol.% 까지 치환(置換)하고 있다. $Ta^{+5}$와 $Nb^{+5}$는 Fe* 쌍치환관계(雙置換關係)이며 $Ta^{+5}$는 $Ti^{+4}$와 화학적(化學的) 친화관계(親化關係)로서 밀접(密接)히 수반(隨伴)된다. 이상구조(異常構造)가 발달(發達)된 석석(錫石)은 결정(結晶)의 내핵(內核)에서부터, 외각(外殼)으로 갈수록 Ta/Nb 비(比)가 증가(增加)하며, 이는 온도(溫度)의 하강(下降)에 따른 Ta의 참여효과(參與效果) 가 높아지는데 기인(起因)된다. 함(含)Ta-금홍석(金紅石)은 $TiO_2$:57.41-86.00wt.%, $Ta_2O_5$:5.08-21.51 wt.%, $Nb_2O_5$:1.60-6.81 wt.%, FeO*:2.06-5.85 wt.% 그리고 $SnO_2$:1.74-10.35 wt.%의 화학조성(化學造成)으로 구성(構成)되어 있다. 본 광물(鑛物)은 탄탈라이트-콜롬바이트에 비(比)하여 Ta/Ta+Nb의 비(比)가 높다. 탄탈라이트-콜롬바이트의 화학조성(化學造成)에 의하면, Ta/Ta+Nb가 증가(增加)하고, Mn/Mn+Fe*는 감소(減少)하는 분결경향(分結傾向)을 보여 주고 있다. 이것은 분결작용(分結作用)이 진행(進行)되는 동안 Ta의 활동도(活動度)가 증가(增加)되는 것으로 Li과 F가 고갈(枯渴)되고, Be과 P가 풍부(豊富)한 환경(環境)을 지시(指示)하는 것이다. 이와같은 환경(環境)은 순경(順鏡) 페그마타이트에 Li과 F 운모(雲母)의 부재(否在)와 탄탈라이트와 녹주석(綠柱石)이 석석(錫石) 광화작용(鑛化作用)과 밀접(密接)히 수반(隨伴)되는 것과 일치(一致)하는 것이다. 본 페그마타이트는 Ta-Be 복합형(複合型)의 페그마타이트로서 석석(錫石)은 탄탈라이트-콜룸바이트, 녹주석(綠柱石) 등(等)의 분결작용(分結作用)을 수반(隨伴)하며 형성(形成)되었다.

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

• Bulletin of the Korean Chemical Society
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• 제28권10호
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• pp.1797-1802
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• 2007

The kinetics and mechanism of the nucleophilic substitution reactions of diphenyl phosphinic (1) and thiophosphinic (2) chlorides with substituted X-pyridines are investigated kinetically in acetonitrile at 35.0 and 55.0 oC, respectively. A concerted mechanism with backside nucleophilic attack is proposed for the pyridinolysis of 1, on the basis of the linear Bronsted plot with the βX value of 0.68. In the case of the pyridinolysis of 2, the Hammett and Bronsted plots are biphasic concave upwards with the break point at 3- phenyl pyridine. These results indicate a change in mechanism from a concerted SN2(P) process with direct backside nucleophilic attack for less basic nucleophiles (X = 3-CN-3-Ph) to a stepwise process with frontside attack for more basic nucleophiles (X = 4-MeO-3-Ph). Apparent secondary inverse kinetic isotope effects with deuterated pyridine (C5D5N), kH/kD < 1, are observed for the pyridinolysis of 1 and 2.

• Journal of Electrochemical Science and Technology
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• 제6권2호
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• pp.65-74
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• 2015

This work examines the characterization and corrosion behaviour of laser alloyed UNSG10150 steel with three different premixed composition Zn-Sn binary powders using a 4.4 kW continuous wave (CW) Rofin Sinar Nd:YAG laser processing system. The steel alloyed samples were cut to corrosion coupons, immersed in sulphuric acid (0.5 M H₂SO₄) solution at 30℃ using electrochemical technique and investigated for its corrosion behaviour. The morphologies and microstructures of the developed coated and uncoated samples were characterized by Optic Nikon Optical microscope (OPM) and scanning electron microscope (SEM/EDS). Moreover, X-ray diffractometer (XRD) was used to identify the phases present. An enhancement of 2.7-times the hardness of the steel substrate was achieved in sample A₁ which may be attributed to the fine microstructure, dislocations and the high degree of saturation of solid solution brought by the high scanning speed. At scanning speed of 0.8 m/min, sample A₁ exhibited the highest polarization resistance R_p (1081678 Ωcm² ), lowest corrosion current density i_corr (4.81×10⁻⁸A/cm² ), and lowest corrosion rate Cr (0.0005 mm/year) in 0.5 M H₂SO₄. The polarization resistance R_p (1081678 Ωcm² ) is 67,813-times the polarization of the UNSG10150 substrate and 99.9972% reduction in the corrosion rate.

• 자원환경지질
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• 제27권3호
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• pp.237-246
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• 1994

Tin mineralizations in South Korea have been found only in the Ulchin and Sangdong areas. They appear to be in close spatial association with the Wangpiri granitoid in the UlChin area, and the Nonggeori and Naedeogri granites in the Sangdong area. However, previous works have revealed that there are considerable differences in geological setting, mineralogical and geochemical compositions among these granitoids concerned. The roles of discriminant and multiple regression analysis have been examed to establish geochemical differences among the tin-granitoids and to identify elements relating to tin mineralizations. The data set used in this study consists of 60 observations with 29 elements which are cited from pre-existing publications. A stepwise discriminant analysis determined the group of variables that differentiate between samples from four training sets; Buncheon, Wangpiri, Nonggeori and Naedeogri granitoids. These granitoids were most effectively discriminated on the basis of major elements FeO, CaO and $P_2O_5$ and also by the trace elements Rb and Zr. Results of the multiple regression analysis shows that the level of Sn in granitoids depends positively on ones of MnO, Rb and FeO and negatively $P_2O_5$. Graphical representation of discriminant scores on sampling locations greatly aid recognition of differences in the geochemical characteristics in terms of spatial distribution of granitoids examed. The application of the discriminant analysis provides a potential means of identifying and comparing geochemical characteristics.

• Journal of Microbiology and Biotechnology
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• 제17권11호
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• pp.1789-1796
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• 2007

A ${\beta}$-glucosidase with the molecular mass of 160,000 Da was purified to homogeneity from cell extract of a cellulolytic bacterium, Cellulomonas uda CS1-1. The kinetic parameters ($K_m$ and $V_{max}$) of the enzyme were determined with pNP-cellooligosccharides (DP 1-5) and cellobiose. The molecular orbital theoretical studies on the cellulolytic reactivity between the pNP-cellooligosaccharides as substrate (S) molecules and the purified ${\beta}$-glucosidase (E) were conducted by applying the frontier molecular orbital (FMO) interaction theory. The results of the FMO interaction between E and S molecules verified that the first stage of the reaction was induced by exocyclic cleavage, which occurred in an electrophilic reaction based on a strong charge-controlled reaction between the highest occupied molecular orbital (HOMO) energy of the S molecule and the lowest occupied molecular orbital (LUMO) energy of the hydronium ion ($H_3O^+$), more than endocyclic cleavage, whereas a nucleophilic substitution reaction was induced by an orbital-controlled reaction between the LUMO energy of the oxonium ion ($SH^+$) protonated to the S molecule and the HOMO energy of the $H_2O_2$ molecule. A hypothetic reaction route was proposed with the experimental results in which the enzymatic acid-catalyst hydrolysis reaction of E and S molecules would be progressed via $SN_1$ and $SN_2$ reactions. In addition, the quantitative structure-activity relationships (QSARs) between these kinetic parameters showed that $K_m$ has a significant correlation with hydrophobicity (logP), and specific activity has with dipole moment, respectively.