• Polymer(Korea)
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• v.25 no.5
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• pp.719-727
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• 2001

Recently it was found that the charge carrier transport properties are significantly enhanced due to effective intermolecular $\pi$-orbital overlapping and low disorder of hopping sites caused by self-organization of liquid crystal molecules. In this study, the xerographic properties of a double-layer photoconductor doped with nematic liquid crystal, 4-pentyl-4'-cyanoterphenyl (5CT), as a charge-carrier transport material to enhance the charge-tarrier mobility were investigated. From the results of measured surface voltage properties for the photoconductor doped with various concentrations of liquid crystal, 5CT, the initial voltage was found to increase with the concentration of 5CT and the dark decay decreased with the concentration of 5CT. The highest sensitivity was obtained at a specific concentration, 40wt% 5CT. The fluorescence behavior of the carrier transport layer (CTL) was also investigated. It was found that the charge-carrier transport properties of the organic photoconductor depend on the charge-carrier transport properties of the complex. The TNF : 5CT (40 wt%) and OXD : 5CT (40 wt%)samples showed the highest sensitivity because the greatest charge transport complex was termed between the charge-carrier transport materials in these samples.

• Journal of the Korean Magnetic Resonance Society
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• v.9 no.1
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• pp.67-73
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• 2005

$^{27}AI$ triple quantum magic angle spinning (3QMAS) NMR spectra of several mordenite (MOR) sample were simulated with the point charge model method and compared with experimental 3QMAS spectra. Signal positions from different tetrahedral (T) sites in 3QMAS spectra are mainly governed by local structures of T sites such as T-O-T angles and T-O bond lengths. When preparation methods, cations in addition to Si/Al rations vary, the local structures of T sites in MOR change enough to alter signal patterns in 3QMAS of MOR. This inhibits to study the of Al distribution variation over 4 different T sites in mordenite during process such as dealumination by 3QMAS spectra.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3815-3817
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• 2010

• The Korean Journal of Emergency Medical Services
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• v.7 no.1
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• pp.179-198
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• 2003

If see disaster administration system of our country, start in terms of is coping by countermeasure after four immediately after disaster occurrence many problems blessing with a sons by tribe and so on of link nature between formation, disaster administration complete charge utensil's absence, disaster charge manpower and budget be indicated and join. If examine improvement way accordingly, is as following ; Necessity of synthetic disaster administration system, Fire fighting formation's independence guarantee, Integration of fire fighting connection similarity business, Disaster administration's permanent establishment complete charge utensil's necessity, Disaster administration midautumn complete charge utensil at a metropolitan autonomous fire fighting system reorganization, Role division of labor between center and local government, Disaster administration professional human strength positivity, Disaster administration information system construction practical use, Equipment and improvement of budget state, Education public information for safety culture consciousness fixing, Internationalization of fire fighting business, globalization propulsion, Structure, member of rescue confrontation system and efficiency. Fire fighting environment is changing greatly, and fire fighting must become center to correspond to do confrontation that do one thing troble when produce disaster.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.94-94
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• 2009

최근 실리콘 태양전지는 점점 얇아 지는 추세에 있다. 실리콘 태양전지에 있어 실리콘의 두께를 감소시키는 것은 실리콘 소모량을 줄이는데 있어 필수적인 조건이 되었다. 이에 따라 실리콘 표면의 passivation도 더욱 중요하게 여겨지고 있다. 실리콘 태양전지의 passivation막의 한 종류인 $Al_2O_3$는 다른 산화막 물질들과는 달리 negative fixed charge를 가지고 있고 charge의 양이 다른 산화막의 density보다 높아 p-type 실리콘의 경우 후면 passivation막으로 이용이 고려되고 있다. 본 연구에서는 atomic layer deposition으로 $Al_2O_3$막을 실리콘 위에 증착하여 열처리에 따른 그 특성을 비교하고 태양전지를 제작하였다. $Al_2O_3$막을 rapid thermal annealing을 통해 서로 다른 분위기에서 열처리 한 결과를 capacitance-voltage를 통해 측정하여 비교, 분석하였고 ellipsomety 분석을 통해 광학적 특성을 비교하였다. 또한 열처리 온도의 변화에 따른 $Al_2O_3$내에 charge에 변화가 있다는 것을 관찰하였다. 이러한 charge의 변화가 태양전지의 passivation에 영향을 주는지 관찰하기 위해 Quasi-steady state photoconductace를 통해 lifetime의 변화를 관찰 하였다. 이러한 실험결과로부터 열처리 분위기와 온도를 최적화 하여 태양전지 passivation 특성을 증가시킬 수 있었다.

• Structural Engineering and Mechanics
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• v.53 no.5
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• pp.897-919
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• 2015

In this study, the effects of ground shocks due to explosive loads on the dynamic response of historical masonry bridges are investigated by using the multi-point shock response spectrum method. With this purpose, different charge weights and distances from the charge center are considered for the analyses of a masonry bridge and depending on these parameters frequency-varying shock spectra are determined and applied to each support of the two-span masonry bridge. The net blast induced ground motion consists of air-induced and direct-induced ground motions. Acceleration time histories of blast induced ground motions are obtained depending on a deterministic shape function and a stationary process. Shock response spectrums determined from the ground shock time histories are simulated using BlastGM software. The results obtained from uniform and multi-point response spectrum analyses cases show that significant differences take place between the uniform and multi-point blast-induced ground motions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.1
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• pp.73-77
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• 2021

Inorganic-organic hybrid perovskite solar cells have demonstrated considerable improvements, reaching 25.5% of certified power conversion efficiency in 2020 from 3.8% in 2009. In normal structured perovskite solar cells, TiO2 electron-transporting materials require heat treatment process at a high temperature over 450℃ to induce crystallinity. Inverted perovskite solar cells have also been studied to exclude the additional thermal process by using [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as a non-oxide electron-transporting layer. However, the drawback of the PCBM layer is a charge accumulation at the interface between PCBM and a metal electrode. The impact of bathocuproin (BCP) buffer layer on photovoltaic performance has been investigated herein to solve the problem of PCBM. 2-mM BCP-modified perovskite solar cells were observed to exhibit a maximum efficiency of 12.03% compared with BCP-free counterparts (5.82%) due to the suppression of the charge accumulation at the PCBM-Au interface and the resulting reduction of the charge recombination between perovskite and the PCBM layer.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1604-1612
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• 2011

We developed three-dimensional quantitative structure activity relationship (3D-QASR) models for 17 adamantyl derivatives as P-glycoprotein (P-gp) inhibitors. Eighteen different partial charge calculation methods were tested to check the feasibility of the 3D-QSAR models. Best predictive comparative molecular field analysis (CoMFA) model was obtained with the Austin Model 1-Bond Charge Correction (AM1-BCC) atomic charge. The 3D-QSAR models were derived with CoMFA and comparative molecular similarity indices analysis (CoMSIA). The final CoMFA model ($q^2$ = 0.764, $r^2$ = 0.988) was calculated with an AM1-BCC charge and electrostatic parameter, whereas the CoMSIA model ($q^2$ = 0.655, $r^2$ = 0.964) was derived with an AM1-BCC charge and combined steric, electrostatic, hydrophobic and HB-acceptor parameters. Leave-five-out (LFO) cross-validation was also performed, which yielded good correlation coefficient for both CoMFA (0.801) and CoMSIA (0.656) models. Robustness of the developed models was checked further with 1000 run bootstrapping analyses, which gave an acceptable correlation coefficient for CoMFA (BS-$r^2$ = 0.997, BS-SD = 0.003) and CoMSIA (BS-$r^2$ = 0.996, BS-SD = 0.018).

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.587-596
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• 2014

A new ${\pi}$-stacked donor-acceptor (D-A) system, [Ru(1-([2,2'-bipyridine]-6-yl-methyl)-3-(2-cyclohexa-2',5'-diene-1,4-dionyl)-1H-imidazole)(2,2':6',2"-terpyridine)]$[PF_6]_2$ (ImQ_T), has been synthesized and characterized. Similar to its precedent, [Ru(6-(2-cyclohexa-2',5'-diene-1,4-dione)-2,2':6',2"-terpyridine)(2,2':6',2"-terpyridine)]$[PF_6]_2$ (TQ_T), this system has a cofacial alignment of terpyridine (tpy) ligand and quinonyl (Q) group, which facilitates an electron transfer through ${\pi}$-stacked manifold. Despite the presence of lowest-energy charge transfer transition from the Ru-based-HOMO-to-Q-based-LUMO (MQCT) predicted by theoretical calculations by using time-dependent density functional theory (TD-DFT), the experimental steady-state absorption spectrum does not exhibit such a band. The selective excitation to the Ru-based occupied orbitals-to-tpy-based virtual orbital MLCT state was thus possible, from which charge separation (CS) reaction occurred. The photo-induced CS and thermal charge recombination (CR) reactions were probed by using ultrafast visible-pump/mid-IR-probe (TrIR) spectroscopic method. Analysis of decay kinetics of Q and $Q^-$ state CO stretching modes as well as aromatic C=C stretching mode of tpy ligand gave time constants of <1 ps for CS, 1-3 ps for CR, and 10-20 ps for vibrational cooling processes. The electron transfer pathway was revealed to be Ru-tpy-Q rather than Ru-bpy-imidazol-Q.

• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.2135-2146
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• 2022

A nuclear energy facility is one of the most critical facilities to be safely protected during and after operation because the physical destruction of its barriers by an external attack could release radioactivity into the environment and can cause harmful effects. The barrier walls of nuclear energy facilities should be sufficiently robust to protect essential facilities from external attack or sabotage. Physical protection system (PPS) vulnerability assessment of a typical small nuclear research reactor was carried out by simulating an external attack with a tri-nitro toluene (TNT) shaped charge and results are presented. The reinforced concrete (RC) barrier wall of the research reactor located at a distance of 50 m from a TNT-shaped charge was the target of external attack. For the purpose of the impact assessment of the RC barrier wall, a finite element method (FEM) is utilized to simulate the destruction condition. The study results showed that a hole-size of diameter 342 mm at the front side and 364 mm at the back side was created on the RC barrier wall as a result of a 143.35 kg TNT-shaped charge. This aperture would be large enough to let at least one person can pass through at a time. For the purpose of the PPS vulnerability assessment, an Estimate of Adversary Sequence Interruption (EASI) model was used, which enabled the determination of most vulnerable path to the target with a probability of interruption equal to 0.43. The study showed that the RC barrier wall is vulnerable to a TNT-shaped charge impact, which could in turn reduce the effectiveness of the PPS.