• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1573-1578
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• 2009

A computational study of the reactions between Zn-containing species, the products of the thermal decomposition of diethylzinc (DEZn) and water was investigated. The Zn-containing species – $C_2H_5)_2,\;HZnC_2H_5,\;and\;(ZnC_2H_5)_2$ – were assumed to react with water during ZnO metal organic chemical vapor deposition (MOCVD). Density functional theory (DFT) calculations at the level of B3LYP/6-311G(d) were employed for the geometry optimization and thermodynamic property evaluation. As a result dihydroxozinc, $Zn(OH)_2$, was the most probable reaction product common for all three Zn-containing species. A further clustering of $Zn(OH)_2$ was investigated to understand the initial stage of ZnO film deposition. In experiments, the reactions of DEZn and water were examined by in-situ Raman scattering in a specially designed MOCVD reactor. Although direct evidence of $Zn(OH)_2$ was not observed, some relevant reaction intermediates were successfully detected to support the validity of the gas phase reaction pathways proposed in the computational study.

• 대한화학회지
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• 제57권6호
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• pp.712-720
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• 2013

Microwave assisted syntheses of Zn(II), Cd(II) and Hg(II) complexes with 3-aminopyridine (3AP) and nitrite ($NO_2{^-}$) ions have been reported. The metal complexes were characterized by elemental analyses, molar conductance, IR, Far-IR, electronic, NMR ($^1H$, $^{13}C$), thermal and electron impact mass spectral studies. The spectroscopic studies reveal the composition, the nature of nitrite ligand in the complexes, electronic transitions, chemical environments of C and H atoms thermal degradation of the complexes. On the basis of characterization data, distorted tetrahedral geometry is suggested for Zn(II), Cd(II) and Hg(II) complexes. The organic ligand (3AP) and their metal complexes were screened against gram negative pathogenic bacteria and fungi in vitro. The results are compared with our previous report J. Korean Chem. Soc. 2013, 57, 341 on 4-aminopyridine and nitrite ion complexes of the same metal ions.

• 한국군사과학기술학회지
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• 제7권1호
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• pp.34-46
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• 2004

Copper films were prepared by using ECR-MOCVD(Electron Cyclotron Resonance Metal Organic Chemical Vapor Deposition) coupled with a DC bias system. The DC bias is connected to the electrode which placed 1∼3cm above the polymer substrate. The pulse electrical field around the electrode attracts the positive charged copper ions generated from the dissociation of copper precursor, $Cu(hfac)_2$, under ECR plasma. Condensation of supersaturated copper ions in the space between the electrode and substrate, makes it possible to deposit copper film on the polymer substrate even at room temperature. In this study, optimization of the electrode configuration was carried out in order to obtain the uniform films. The uniformity of the deposited films were closely related to the parameters of electrode geometry such as electrode shape, thickness, grid size and the spacing between electrodes. The most uniform copper film was observed with the electrode that enabled uniform electrical field distribution across the whole dimension of electrode.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.222-222
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• 2010

Transparent semiconductor oxide thin films have been attracting considerable attention as potential channel layers in thin film transistors (TFTs) owing to their several advantageous electrical and optical characteristics such as high mobility, high stability, and transparency. TFTs with ZnO or similar metal oxide semiconductor thin films as the active layer have already been developed for use in active matrix organic light emitting diode (AMOLED). Of late, there have been several reports on TFTs fabricated with InZnO, AlZnSnO, InGaZnO, or other metal oxide semiconductor thin films as the active channel layer. These newly developed TFTs were expected to have better electrical characteristics than ZnO TFTs. In fact, results of these investigations have shown that TFTs with the new multi-component material have excellent electrical properties. In this work, we present TFTs with inverted coplanar geometry and with a novel HfInZnO active layer co-sputtered at room temperature. These TFTs are meant for use in low voltage, battery-operated mobile and flexible devices. Overall, the TFTs showed good performance: the low sub-threshold swing was low and the $I_{on/off}$ ratio was high.

• Bulletin of the Korean Chemical Society
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• 제21권9호
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• pp.923-928
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• 2000

[FeIII(BBA)DBC]ClO4 as a new functional model for catechol dioxygenases has been synthesized, where BBA is a bis(benzimidazolyl-2-methyl)amine and DBC is a 3,5-di-tert-butylcatecholate dianion.The BBA complex has a structuralfeature that iron cent er has a five-coordinate geometry similar to that of catechol dioxygenase-substrate complex.The BBA complex exhibits strong absorptionbands at 560 and 820 nm in CH3CN which are assigned to catecholate to Fe(III) charge transfer transitions. It also exhibits EPR signals at g = 9.3 and 4.3 which are typical values for the high-spin FeIII (S = 5/2) complex with rhombicsymmetry. Interestingly, the BBA complex reacts with O2 within an hour to afford intradiol cleavage (35%) and extradiol cleavage (60%) products. Surprisingly, a green color intermediate is observed during the oxygenation process of the BBA com-plex in CH3CN. This green intermediate shows a broad isotropic EPR signal at g = 2.0. Based on the variable temperature EPR study, this isotropic signalmight be originated from the [Fe(III)-peroxo-catecholate] species havinglow-spin FeIII center, not from the simple organic radical. Consequently,it allows O2 to bind to iron cen-ter forming the Fe(III)-superoxide species that converts to the Fe(III)-peroxide intermediate. These present data can lead us tosuggest that the oxygen activation mechanism take place for the oxidative cleavingcatechols of the five-coordinate model systems for catechol dioxygenases.

• 한국산림과학회지
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• 제90권4호
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• pp.450-457
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• 2001

산림의 수원함양기능 지표인 표층토양에서의 조공극율(粗孔隙率)(pF2.7) 에 영향하는 입지환경인자를 밝히기 위해 1994년 3월부터 10월까지 전국의 활엽수림 표본조사구를 대상으로 업지, 토양, 임분환경인자 등 총 15인자에 대하여 spss/pc+를 이용하여 상관 분석하였다. 표층토양에서의 조공극률에 영향을 미치는 수고, 하층식생 피복도, 토양의 유기물함량비 3개 인자가 유의한 정(正)의 상관관계를, 표층토양의 견밀도가 1% 수준에서 유의한 부(負)의 상관관계를 나타내었다. Stepwise를 이용한 다중회귀분석결과 표층토양에서의 조공극률에 영향하는 인자는 표층토양의 견밀도, 토양의 유기물함량비 2개 인자이었다. 활엽수림의 수원함양기능 증진을 위한 시업은 표층토양의 조공극 발달이 촉진되도록 하층식생 피복도가 30%에서 80%를 유지하도록 실시해야 할 것으로 판단된다.

• Journal of Mechanical Science and Technology
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• 제18권9호
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• pp.1680-1688
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• 2004

The information indicating device plays an important part in the information times. Recently, the classical CRT (Cathod Ray Tube) display is getting transferred to the LCD (Liquid Crystal Display) one which is a kind of the FPDs (Flat Panel Displays). The OLED (Organic Light Emitting Diodes) display of the FPDs has many advantages for the low power consumption, the luminescence in itself, the light weight, the thin thickness, the wide view angle, the fast response and so on as compared with the LCD one. The OLED has lately attracted considerable attention as the next generation device for the information indicators. And also it has already been applied for the outside panel of a mobile phone, and its demand will be gradually increased in the various fields. It is manufactured by the vapor deposition method in the vacuum state, and the uniformity of thin film on the substrate depends on the temperature distribution in the point-cell source. This paper describes the basic concepts that are obtained to design the point-cell source using the computational temperature analysis. The grids are generated using the module of AUTOHEXA in the ICEM CFD program and the temperature distributions are numerically obtained using the STAR-CD program. The temperature profiles are calculated for four cases, i.e., the charge rate for the source in the crucible, the ratio of diameter to height of the crucible, the ratio of interval to height of the heating bands, and the geometry modification for the basic crucible. As a result, the blowout phenomenon can be shown when the charge rate for the source increases. The temperature variation in the radial direction is decreased as the ratio of diameter to height is decreased and it is suggested that the thin film thickness can be uniformed. In case of using one heating band, the blowout can be shown as the higher temperature distribution in the center part of the source, and the clogging can appear in the top end of the crucible in the lower temperature. The phenomena of both the blowout and the clogging in the modified crucible with the nozzle-diffuser can be prevented because the temperature in the upper part of the crucible is higher than that of other parts and the temperature variation in the radial direction becomes small.

• 한국산림과학회지
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• 제90권3호
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• pp.314-323
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• 2001

산림의 수원함양기능 지표로서 표층토양에서의 조공극률(粗孔隙率)(pF2.7)에 영향하는 인자를 밝히기 위해 1993년 3월부터 10월까지 전국의 침엽수림 표본조사구를 대상으로 입지, 토양, 임분환경인자 등 총 23개 조사항목에 대하여 상관분석하였다. 표층토양에서의 조공극률에 영향을 미치는 유의한 인자는 표층토양에서의 조대공극률(粗大孔隙率)(pF1.6), 경사도, 상층식생 울폐도, F층의 두께, 토양의 유기물함량비, 임목축적 등 6개 인자가 정(定)의 상관관계를, 점토함량비, 표층토양의 견밀도, A층, B층 토양견밀도 등 4개 인자가 각각 5%, 1% 수준에서 유의한 부(負)의 상관관계를 나타내었다. 또한, stepwise를 이용한 다중회귀분석결과 표층토양에서의 조공극률에 영향하는 인자는 표층토양의 견밀도, 상층임분 지하고, 임목축적, B층 토양의 견밀도, 토양의 유기물함량비 등 5개 인자이었다. 침엽수림의 수원함양기능 증진을 위한 시업은 표층토양의 조공극 발달이 촉진되도록 상충식생 울폐도가 80%를 넘게 되었을 때 실시해야 할 것으로 판단된다.

• 대한수학교육학회지:수학교육학연구
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• 제25권2호
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• pp.225-240
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• 2015

본 연구에서는 중점연결정리의 사각형으로의 확장을 소재로 학교수학에서 다루어지는 증명의 대표성에 대해 고찰하였다. 다양한 사각형을 생각하고, 그에 맞는 중점연결정리의 확장을 증명하였으며, 이들 증명 간의 관계를 파악하여 학교수학에서의 증명이 대표성을 가짐을 보였다. 한편, 이러한 내용에 기초한 실태조사에서 학생들은 사각형 종류의 일부만을 찾았으며, 찾은 사각형 각각에 대한 증명은 쉽게 완성하였으나, 같은 수학적 사실을 증명하고 있음에도 대상 도형이 바뀌면 다른 증명 방법이나 수학적 개념을 사용하는 경향을 보였다. 따라서 증명들 간의 관계를 파악하는 것을 어려워하였다. 이러한 사실들은 구체적 도형에 대한 증명은 할 수 있으나, 증명들 간의 관계를 이해하여 일반화하는 증명의 대표성에 대한 이해는 부족함을 보여준다. 따라서 증명활동이 유기적이고 의미론적으로 이루어질 필요가 있음을 알 수 있다.

• 한국유체기계학회 논문집
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• 제19권6호
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• pp.50-54
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• 2016

The performance of a scroll expander is the most important factor for the efficiency of small scale Organic Rankine cycle waste heat power generation systems. In this research, a scroll compressor was purchased and operated in reverse to function as a scroll expander. With air as a working fluid, a series of performance test were conducted on this expander by varying the inlet and outlet pressure. Secondly, We have tested through 2000 to 3500 rpm rotational speed to find the maximum power and efficiency of the expander. And last, It was observed in the initial experiments that the design of the expander's orbiting scroll wrap partially blocked the fluid intake which may have caused unnecessary flow resistance. To verify this theory, a small part of the scroll wrap was removed and the performance test was redone. It was observed that the lower back pressure assure the higher efficiency and power of expander and the rotational speed that shows maximum adiabetic efficiency of scroll expander is 69% at 2500 rpm. And by modified wrap of the scroll, we could get volume flow rate for 13% to 19% and power for 5% to 18% increased. But the maximum efficiency of the modified scroll was decreased 8%.