• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1215-1217
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• 1993

• 한국자기공명학회:학술대회논문집
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• 한국자기공명학회 2002년도 International Symposium on Magnetic Resonance
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• pp.89-89
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• 2002

• 자원환경지질
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• 제32권3호
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• pp.307-315
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• 1999

Four organic polymers were mixed with mothmorillonite. Two cationic polymers a hi로 molecular weight polyacrylamide (494C) and a low molecular weight polymer (587C).Two anionic polymers include a high molecular weight polymer (aerotil). Each clay supension series were allowed to stand for 24 hours and were centrifuged, and the clay plugs were washed and dried. The dried samples investigated by XRD, IR and CEC measurement. The suspended clay containing anionic polymers was not flocculated at any concentratuons of polymer. But the suspendions containing two cationic polymers were rapidly flocculated at almost all concentrations. the d(001) spacings of Na-montmorillonite after being with cationic polymer 587C show about 15$\AA$ suggesting the polymers may have entered the interlayer spaces. The polymer 494C-treated sample produced double peaks of about 12 and 15$\AA$ in XRD. It indicates that the high molecular weight polymer. And cationic polymer 494C may be adsorbed mainy on the outside surface of clay, and some polymers may peretrate into olny interlayers in the margin of montmorillonite particles because of its high molecular weught. CEC of polumer 587-treated sample was reduecd mmarkedly suggesting polymer blocks CEC sites. The d(001) spacings of Ca-montmorillonite after being treated with cationic polymers show about 15$\AA$ suggesting that the interlayer spaces have not been expanded. In the experiment using a dilute Ca-bearing solution, the suspended caly containinf anionic polymers was flocculated. The results indicate that the flocculation behavior of montmorillonite-polymer supension depends on not only polymer properties such as concentration, electric charge and molecular weight but also compositions of solvent.

• 한국식품과학회지
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• 제22권7호
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• pp.805-811
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• 1990

대두단백질의 기능성을 개선하기 위하여 고정화된 트립신 및 키모트립신으로 가수분해시킨 후, 이 대두단백 가수물의 기능성을 조사하였다. Ferguson plot으로부터 가수분해물의 평균분자량 및 평균전하를 계산하여 대두단백의 기능성을 나타내는 인자로 이용하였다. 즉, 단백질의 평균분자량을 평균전하로 나눈 값은 단백가수물의 용해도, 포수력, 포유력, 유화도 등의 기능성을 예측하는데 이용될 수 있었다. 이 분자비가 낮으면 용해도는 향상되었으나 포수력은 감소되었으며 중간범위일 경우 포유력과 유화도는 증가되는 경향을 나타냈다.

• 한국응용과학기술학회지
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• 제31권3호
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• pp.402-407
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• 2014

Herein, we describe the effect of the cooling-off condition of a solution-processed 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) film on its molecular distribution and the resultant electrical properties. Since the solvent in a TIPS-pentacene droplet gradually evaporates from the rim to the center exhibiting a radial form of solute, for a quenched case, domains of the TIPS-pentacene film are aboriginally spread showing original features of radial shape due to suppressed molecular rearrangement during the momentary cooling period. For the slowly cooled case, however, TIPS-pentacene molecules are randomly rearranged during the long cooling period. As a result, in the lopsided electrodes structure proposed in this work, the charge transport generates more effectively under the case for radial distribution induced by the quenching technique. It was found that the molecular redistribution during the cooling-period plays an important role on the magnitude of the mobility in a solution-processed organic transistor. This work provides at least a scientific basis between the molecular distribution and electrical properties in solution-processed organic devices.

• Transactions on Electrical and Electronic Materials
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• 제17권3호
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• pp.134-138
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• 2016

The fullerene solar cells are becoming a feasible choice due to the advanced developments in donor materials and improved fabrication techniques of devices. Recently, sufficient optimization and improvements in the processing techniques like incorporation of solvent vapor annealing (SVA) with additives in solvents has become a major cause of prominent improvements in the performance of organic solar cell-based devices . On the other hand, the challenge of reduced open circuit voltage (V_oc) remains. This study presents an approach for significant performance improvement of overall device based on organic small molecular solar cells (SMSCs) by following a two step technique that comprises thermal annealing (TA) and SVA (abbreviated as SVA+TA). In case of exclusive use of SVA, reduction in V_oc can be eliminated in an effective way. The characteristics of charge carriers can be determined by the measurement of transient photo-voltage (TPV) and transient photo-current (TPC) that determines the scope for improvement in the performance of device by two step annealing. The recovery of reduced V_oc is linked with the necessary change in the dynamics of charge that lead to increased overall performance of device. Moreover, SVA and TA complement each other; therefore, two step annealing technique is an appropriate way to simultaneously improve the parameters such as V_oc, fill factor (FF), short circuit current density (J_sc) and PCE of small molecular solar cells.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.126-126
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• 2017

Using first principles calculations we unveil fundamental mechanism of hydrolysis reactions of two hazardous chemicals $PCl_3$ and $POCl_3$ with molecular water clusters nearby. It is found that the water molecules play a key role as a catalyst significantly lowing the activation barriers by transferring its protons to the reaction intermediates. Interestingly, torsional angles of molecular complexes at transition states are identified as a vital descriptor on the reaction rate. Analysis of charge distribution over the complexes further reinforces the finding with atomic level correlation between the torsional angle and variation of the orbital hybridization state of P in the complex. Electronic charge separation (or polarization) enhances thermodynamic stability of the activated complex at transition state and reduces the activation energy through hydrogen bonding network with water molecules nearby. Calculated potential energy surfaces (PES) for the hydrolysis reactions of $PCl_3$ and $POCl_3$ depict their two contrastingly different profiles of double- and triple-deep wells, respectively. It is ascribed to the unique double-bonding O=P in the $POCl_3$. Our results on the activation free energy show well agreements with previous experimental data within $7kcalmol^{-1}$ deviation.

• Macromolecular Research
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• 제15권2호
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• pp.114-128
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• 2007

Polyimides are one of the most important classes of polymers used in the microelectronics and photoelectronics industries. Because of their high thermal stability, chemical resistance, and good mechanical and electric properties, polyimides are often applied in photoresists, passivation and dielectric films, soft print circuit boards, and alignment films within displays. Recently, fully aliphatic and alicyclic polyimides have found applications as optoelectronics and inter layer dielectric materials, due to their good transparencies and low dielectric constants $(\varepsilon)$. The low molecular density, polarity and rare probability of forming inter- or intra-molecular charge transfers, resulting in lowering of the dielectric constant and high transparency, are the most striking characteristics of aliphatic polyimide. However, the ultimate end use of polyimides derived from aliphatic monomers is in their targeted applications that need less stringent thermal requirements. Much research effort has been exerted in the development of aliphatic polyimide with increased thermal and mechanical stabilities, while maintaining their transparencies and low dielectric constants, by the incorporation of rigid moieties. In this article, the recent research process in synthesizing fully aliphatic polyimides, with improved dimensional stability, high transparency and low $\delta$values, as well as the characterizations and future scope for their application in micro electric and photo-electronic industries, is reviewed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.379-380
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• 2008

Molecular Dynamics (MD) simulations have been used to model the dynamics of the charge-compensating sodium ions in the non-stoichiometric hollandite Nax$(Ti_{8-x}Cr_x)O_{16}$. These interstitial ions reside in 'tunnels' in the crystal structure and move under the forces of both the ions making up the cage structure and the many body interactions of the other sodium ions in the tunnel. The Velocity Autocorrelation Function (VAF) of the sodium ions is calculated for a range of temperature from 250K to 1000K and converted into the linear ac-conductivity and ac-susceptibility response via Fourier transformation. A peak is found in the conductivity around $6\times10^{12}$ Hz that has some of the character of a Poley absorption. Here it is shown to be due to an harmonically coupled site vibrations of the sodium atoms, which extend only over a limited range. At frequencies below the peak the conductivity tends towards a constant i.e. dc value corresponding to a constant flow of ions through the simulation cell. At high temperatures the conductivity due to this ion transport process behaves like a metal with an insulator to metal transition occurring around a specific temperature.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.70-70
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• 2013

As the costs of carbon-footprinetd fuels grow continuously and simultaneously atmospheric carbon dioxide concentration increases, solar fuels are receiving growing attention as alternative clean energy carriers. These fuels include molecular hydrogen and hydrogen peroxide produced from water, and hydrocarbons converted from carbon dioxide. For high efficiency solar fuel production, not only light absorbers (oxide semiconductors, Si, inorganic complexes, etc) should absorb most sunlight, but also charge separation and interfacial charge transfers need to occur efficiently. With this in mind, this talk will introduce the fundamentals of solar fuel production and artificial photosynthesis, and then discuss in detail on photoelectrochemical (PEC) water splitting and CO2 conversion. This talk largely divides into two section: PEC water oxidation and PEC CO2 reduction. The former is very important for proton-coupled electron transfer to CO2. For this oxidation, a variety of oxide semiconductors have been tested including TiO2, ZnO, WO3, BiVO4, and Fe2O3. Although they are essentially capable of oxidizing water into molecular oxygen, the efficiency is very low primarily because of high overpotentials and slow kinetics. This challenge has been overcome by coupling with oxygen evolving catalysts (OECs) and/or doping donor elements. In the latter, surface-modified p-Si electrodes are fabricated to absorb visible light and catalyze the CO2 reduction. For modification, metal nanoparticles are electrodeposited on the p-Si and their PEC performance is compared.