• Rapid Communication in Photoscience
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• 제1권2호
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• pp.27-29
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• 2012

Noble diamine monomers containing thiophene moiety were prepared, such as 2,5'''-diamino-2, 2':5', 2'':5'', 2'''-quaterthiophene (4TDA) and 2, 5'''''-diamino-3'', 4'''-dihexyl-2,2':5', 2'':5'', 2''':5''', 2'''':5'''', 2'''''-sexithiophene (6TDA). Then, these monomers were utilized to prepare polyimides with 3,6-diphenylpromellitic dianhydride (DPPMDA), 3,6-di(4'-trifluoro-methylphenyl) pyromellitic dianhydride (6FPMDA) or 3,6-di(3',5'-bis (trifluoromethyl)phenyl) pyromellitic dianhydride (12FPMDA) via a conventional two-step process. The polyimides were characterized by FT-IR, TGA and DSC, and then subjected CV, UV-vis and PL measurements. The polyimides containing thiophene moiety exhibited high glass transition temperatures ($280{\sim}310^{\circ}C$) and excellent thermal stability (> $420^{\circ}C$) in air as well as green emission (535~586 nm).

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.158-158
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• 2011

A wide range of techniques for the direct-printing of functional materials have been developed for the fabrication of micro- and nanoscale structures and devices. Here we report a new direct patterning method, liquid bridge-mediated nanotransfer molding (LB-nTM), for the formation of two- or three-dimensional structures with feature sized as small as tens of nanometers over large areas up to 4". LB-nTM is based on the direct transfer of various materials from a mold to a substrate via a liquid bridge between them. The LB-nTM method was applied to the preparation of organic nanowire FETs on flexible substrates.

• 한국세라믹학회지
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• 제42권12호
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• pp.865-871
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• 2005

Submicron thick solid electrolyte membrane is essential to the implementation of low temperature solid oxide fuel cell, and, therefore, development of new electrode structures is necessary for the submicron thick solid electrolyte deposition while providing functions as current collector and fuel transport channel. In this research, a nickel membrane with multi-stage nano hole array has been produced via modified two step replication process. The obtained membrane has practical size of 12mm diameter and $50{\mu}m$ thickness. The multi-stage nature provides 20nm pores on one side and 200nm on the other side. The 20nm side provides catalyst layer and $30\~40\%$ planar porosity was measured. The successful deposition of submicron thick yttria stabilized zirconia membrane on the substrate shows the possibility of achieving a low temperature solid oxide fuel cell.

• Macromolecular Research
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• 제16권7호
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• pp.620-625
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• 2008

A novel nitrogen-phosphorus compound, diphenyl piperazine-1,4-diylbis(methylphosphinate)(DPPMP) was synthesized via a two step reaction and its flame retarding efficiency as a single component additive was investigated. The success of synthesis was confirmed by FTIR and $^1H$ and $^{31}P$ NMR analysis. The product was mixed with polycarbonate (PC), poly(butylene terephtalate) (PBT), ethylene-vinyl-acetate copolymer (EVA), and acrylonitrile-butadiene-styrene copolymer (ABS). The flame-retarding efficiency was evaluated using the limiting oxygen index (LOI) and the UL-94 vertical test methods. The addition of DPPMP enhanced the flame retardancy of the polymers and the V-0 ratings were obtained for the polymers examined in this study at a loading of 7-30 wt%. The gas-phase flame retardancy mode of action was suggested for this material from the thermogrametry experiment results.

• Fibers and Polymers
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• 제4권3호
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• pp.97-101
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• 2003

Polymer/silicate nanocomposites were prepared via two-step manufacturing process: a master batch preparation and then mixing with matrix polymer. A hybrid of PMMA and Na-MMT with exfoliated structure was first prepared by emulsion polymerization of MMA in the presence of Na-MMT. For the case that SAN24, miscible with PMMA, is used as matrix, we could prepare a nanocomposite with exfoliated structure. However, SAN31 nanocomposite shows the aggregation and/or reordering of the silicate layers due to the immiscibility between SAN31 and PMMA.

• 대한화학회지
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• 제21권3호
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• pp.155-160
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• 1977

경쟁 1,2-와 1,4-고리화첨가반응에 대한 frontier 분자궤도와 전전자에너지의 상관도를 작도하고 이 상관도에 의해서 반응기구를 설명할 수 있었다. 고찰해서 유도된 중요 결론은 다음과 같다. 1) HO와 LU사이에 교차가 일어나지 않았다. 그러므로 반응은 열반응이다. 2) diradical을 경유하는 이단계기구가 일단계기구 보다 에너지장벽으로 미루어 보아 유리하다. 3) [2+2]와 [2+4] 고리화첨가물의 생성물분포를 예측할 수 있다.

• Bulletin of the Korean Chemical Society
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• 제25권1호
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• pp.119-121
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• 2004

A new and efficient synthesis of the novel bioactive bis(benzopyrano) fused dihydropyridines is described. The conventionally developed route is a two step multicomponent condensation reaction. This is latter modified by a one pot microwave (MW) assisted reaction using inorganic solid support via the arylidene derivative intermediate. With this environmentally benign approach, the reaction time is brought down from hours to minutes along with a yield enhancement. Furthermore, the role of different solid supports is studied and it is concluded that the acidic alumina is the best solid support for the present investigation.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권3호
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• pp.123-128
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• 2004

In electrical impedance tomography (EIT), the internal resistivity distribution of the unknown object is computed using the boundary voltage data induced by different current patterns using various reconstruction algorithms. This paper presents a new image reconstruction algorithm based on the genetic algorithm (GA) via a two-step approach for the solution of the EIT inverse problem, in particular for the reconstruction of "static" images. The computer simulation for the 32 channels synthetic data shows that the spatial resolution of reconstructed images in the proposed scheme is improved compared to that of the modified Newton-Raphson algorithm at the expense of an increased computational burden.rden.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1997년도 추계총회 및 학술발표회 논문집
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• pp.126-130
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• 1997

A series of Thermoplastic polyurethane elastomers was prepared via a two-step polymerization process. The NCO/OH feed ratio of polyurethane synthesized in this study was varied from 1 to 1.3. Studies have been made on the effects of chemical and physical cross-linkina, and the properties of thermoplastic polyurethane elastomers based on isophorone diisocyanate (IPDI)/1,4-butanediol (BD)/poly(propylene glycol) (PPG, MW:2000), isophorone diisocyanate (IPDI)/BD /poly(oxytetramethylene) glycol (PTMG, MW:2000) was compared. These materials were characterized using FTIR spectrometer, dynamic mechanical thermal analyzer, and tensile retraction tester. PTMG based polyurethane elastomers showed higher elasomeric behavior than PPG based polyurethane elastomers at the same NCO/OH ratio. This feature has been connected with the specific nature of the polyols. The permanent set(%) was decreased with increasing maximum elongation from 50% to 300%.

• Journal of information and communication convergence engineering
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• 제17권4호
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• pp.255-260
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• 2019

A pendubot is a representative example of an underactuated system that has fewer actuators than the degree of freedom of the system. In this study, the characteristics of the pendubot are first reviewed; each part is then designed using Solidworks by dividing the pendubot into three parts: the base frame, first link frame, and second link frame. These three parts are then imported into the Simulink environment via a STEP file format, which is the standard protocol used in data exchange between CAD applications. A 3D model of the pendubot is then constructed using Simscape, and the usefulness of the 3D model is validated by a comparison with a dynamic equation derived using the Lagrangian formulation. A linearized model around an upright equilibrium position is finally obtained, and a sliding mode controller is designed based on the linear quadratic regulator. Simulation results showed that the designed controller effectively maintained upright balance of the pendubot in the presence of disturbance.