• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.1
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• pp.37-43
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• 2022

In this study, we investigated the optical, electrical and exothermic characteristics of ITO/Ag/ITO multilayer structures prepared with various Ag thicknesses on quartz and PI substrates. The transparent conducting properties of the ITO/Ag/ITO multilayer films depended on the thickness of the mid-layer metal film. The ITO/Ag (14 nm)/ITO showed the highest Haccke's figure of merit (FOM) of approximately 19.3×10^-3 Ω^-1. In addition, the exothermic property depended on the substrate. For an applied voltage of 3.7 V, the ITO/Ag (14 nm)/ITO multilayers on quartz and PI substrates were heated up to 110℃ and 200℃, respectively. The bending tests demonstrated a comparable flexibility of the ITO/Ag/IT multilayer to other transparent electrodes, indicating the potential of ITO/Ag/ITO multilayer as a flexible transparent conducting heater.

• Bulletin of the Korean Chemical Society
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• v.28 no.8
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• pp.1358-1362
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• 2007

The structures, energetics and transfer integrals of the acene tetramers up to pentacene are investigated with the ab initio molecular orbital method at the level of second-order Møller-Plesset perturbation theory (MP2). Calculated geometries for the herringbone-style structures found in the crystal structure were characterized as local minima, however the geometrical discrepancy between crystal and MP2 theoretical structure is reasonably small. The binding energy of pentacene tetramer was calculated up to 40 kcal/mol (MP2/6-31G(d)) and about 90 kcal/mol (MP2/aug-cc-pVDZ), and the latter seems to be too much overestimated. The tendency of the hole transfer integrals computed with ab initio MP2/3-21G(d) geometry is well agreement with those estimated with crystal structure with some discrepancy, and the gradual increment of the transfer integrals at the crystal geometry is attributed to mainly packing structure rather than the intrinsic property of acene such as a size of acene.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.5
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• pp.565-572
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• 2002

The design concept of diesel engines for sea-going ships has been directed to Low-speed/Long-Stroke type to improve the efficiencies of combustion and propelling. But time-delay inevitable at low speed gives much difficulties for governors to control the engine speed because they would be apt to go into unstable region especially when operating at low speed. The purpose of this paper is to study the problem of how the governor gain can be calculated dynamically in accordance with the valiance of engine speed to locate the engine still on the properly stable condition. In this study, the property of diesel engine was described as composed of combustion element including dead time and rotating element, and the ultimate gain for the speed control system to be located on the condition of stability limit was proposed based on the frequency characteristics. And the target gains with optimized stability also were proposed by giving proper margin to these ultimate conditions. The results were applied to a model system and the availability was confirmed to be satisfactory.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.498-501
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• 2004

In this study, the threshold voltage and the response time of thermal stressed TN-LCDs showed the same performances on no thermal stressed TN-LCDs. There was little change of value in TN cells. Also, the transmittances of TN-LCDs on the rubbed PI surface were almost same while increasing thermal stress time. However, the thermal stability of TN cell was decreased by the high thermal stress for the long duration. Residual DC was decreased as the thermal stress increases. Especially, when TN cell was stressed more and more by heating, residual DC was changed a lot. As a result, the residual DC property of LCD in projection TV is affected very much by heating.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.3-5
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• 1993

The use of preformed polymers and their cross-linking have been attempted in order to improve the intrinsic fragility of monolayers and Langmuir-Blodgett (LB) films and to make their technological applications possible. It has shown that an imidization followed a polyion-complexation can stabilize the LB films against heat and solvents. And, when the polymer structure was property designed, concurrent removal of the alkyl tails together with imide formation could be accomplished. In this paper, we present a characteristic monolayer behavior of polymer with pendent polyethers and carboxyls, it's polyion-complexed LB film with subphase polymer PAA, and a possible skeletonization of the LB film by thermal imidization. Also, deposition status of LB films are evaluated by using QCM.

• Advances in concrete construction
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• v.7 no.2
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• pp.97-105
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• 2019

In this paper, the workability and static stability were evaluated using a proposed test method. Workability and static stability represent a key property of self-compacting concrete (SCC) in fresh state. A number of standardized test methods were developed to assess these properties. However, no accelerated test method reliably predicts both workability and static stability of SCC. In the present work, a modified K-slump test method was developed to evaluate workability and static stability of SCC. In order to take implicit mixture variations of SCC constituents that can affect fresh SCC properties, a central composite design was adopted to highlight the effect of gravel to sand ratio (G/S), gravel 3/8 to gravel 8/15 ratio (G1/G2), water to cement ratio (W/C), marble powder to cement ratio (MP/C) and superplasticizer content (SP) on workability measured with slump and flow time (T50) tests and static stability measured with sieve stability test (Pi), segregation test index (SSI), Penetration test (Pd) and the proposed K-slump test (Km). The obtained results show that G/S ratio close to 1 and G1/G2 ratio close to 60% can be considered as optimal values to achieve a good workability while ensuring a sufficient static stability of SCC. Acceptable relationships were obtained between Slump flow, Pi, Pd and Km. Results show that the proposed K-slump test allow to assess both workability and static stability of fresh SCC mixtures.

• Polymer(Korea)
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• v.39 no.2
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• pp.275-280
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• 2015

Two series of copolyimides (Co-PIs) were prepared by reacting 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 1,2,4,5-benzentetra carboxylic dianhydride (pyromellitic dianhydride) (PMDA), as dianhydrides based on 4,4'-biphthalic anhydride (BPA) and 2,2'-bis(trifluoromethyl)benzidine (TFB) by using thermal- and chemical imidizations. Co-PIs films with different dianhydride monomer compositions were compared in terms of their thermal properties and optical transparencies. The addition of PMDA was more effective than the addition of 6FDA for improving the thermal properties. Meanwhile, 6FDA is more effective in optical transparencies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.05a
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• pp.61-62
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• 2006

본 연구에서는 대표적인 양친매성분자인 Arachidic acid를 이용하여 박막을 제작하였으며, 층수 변화에 따른 표면이미지와 전압-전류 특성을 측정하였다. Arachidic acid 는 포화지방산으로 ($CH_3(CH_2)_{18}$ COOH)의 구조를 가지며, 크기가 $27.5{\AA}$으로 $CH_3(CH_2)_{18}$의 소수기와 COOH의 친수기로 구성되어 있어, Langmuir-Blodgett (LB) Trough을 사용하여 박막제작과 분자제어가 쉽다. Chloroform을 용매로 하여 2 mmol/l의 농도를 조성하여 ${\pi}$-A 등온선을 통해 기체 상태, 액체 상태, 고체 상태를 관찰하였다. LB 막의 제작 및 평가에서 막의 안정성은 ${\pi}$-A 곡선, AFM(Atomic force microscopy) 등을 통하여 확인하였다. 또한 LB 막을 Metal/유기물 LB막/Metal 구조의 소자로 제작하여 전압-전류 특성을 측정하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.394-395
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• 2006

본 연구에서는 Arachidic acid Langmuir-Blodgett (LB) 막의 표면이미지와 전압-전류 특성을 측정하였다. Arachidic acid는 포화지방산으로 ($CH3(CH_2)_{18}$ COOH)의 구조를 가지며, 크기가 $27.5\;{\AA}$으로 $CH_3(CH_2)_{18}$의 소수기와 COOH의 친수기로 구성되어 있어, LB Trough를 사용하여 박막제작과 분자제어가 쉽다. Chloroform을 용매로 하여 2mmol/l의 농도를 조성하여 ${\pi}$-A 등온선을 통해 기체 상태, 액체 상태, 고체 상태를 관찰하였다. LB막의 제작 및 평가에서 막의 안정성은 ${\pi}$-A곡선, AFM (Atomic force microscopy) 등을 통하여 확인 하였다. 또한 LB 막을 Metal/LB막/Metal 구조의 소자로 제작하여 전압-전류 특성을 측정하였다.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.894-898
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• 2011

The first example of lead compound from $Pb(NO_3)_2$ and $H_3L$ N-heterocyclic ligand $(H_3L\;=\;(HO_2C)_2(C_3N_2)(C_3H_7)CH_2(C_6H_4)(C_6H_3)CO_2H)$, $[Pb_4(L')_4]{\cdot}5H_2O$ 1 (L' = OOC$(C_3H_7)(C_3N_2)CH_2(C_6H_4)(C_6H_3)COO)$, has been obtained under hydrothermal condition by decarboxylation, and characterized by elemental analysis, IR, TGDTA, and single-crystal X-ray diffraction. Compound 1 possesses a rare two-dimensional upper-lower offset terrace-like layer structure. In 1, crystallographic distinct Pb(II) ion adopts five-coordination geometry, and two lattice water molecules occupy the voids between 2-D layers. Results of solid state fluorescence measurement indicate that the emission band 458 nm may be assigned to $\pi^*-n$ and $\pi^*-\pi$ electronic transitions within the aromatic systems of the ligand L', however, the emission bands centred at 555 nm, 600 nm and 719 nm may be derived from phosphorescent emission ($\lambda_{excitation}$ = 390 nm).