• Elastomers and Composites
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• v.24 no.3
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• pp.185-192
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• 1989

The thermal degradation of the homopolymer poly(methyl methacrylate)(PMMA)/tetra cyano quino dimethane(TCNQ) blend and Eccogel/TCNQ blend were carried out using the thermogravimetric method in the stream of nitrogen gas with 60ml/min at various heating rate from 1 to $20^{\circ}C/min$. Friedman and Ozawa mathermatical methods were used to obtain the value of activation energy. Produced electrical properties and activation energy by electric conductivity method that used LCR meter.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.10a
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• pp.71-72
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• 1997

1. 서론 : 공기중의 산소분리용 고분자막은 높은 선택도를 동시에 요구한다. 이 두가지 조건을 만족시키는 소재 개발과 기존의 고분자물질을 수식하는 연구가 진행되고 있다. 고분자막에 대한 수식방법으로는 UV처리, plasma처리등이 있으나, 이들 방법은 선택도는 증가시키나 투과도를 감소시키는 경향이 있다. 기체의 투과저항을 줄이기 위하여 다공성 지지체 위에 박막을 입힌 복합막과 박막의 skin layer와 sub-layer를 갖는 비대칭막은 투과저항을 줄일수 있으나 선택도는 고분자 고유의 80%정도까지 감소되는 것으로 알려졌다. 본 연구의 목적은 고분자 복합막의 투과분리특성을 향상시키기 위한 것으로 지지층의 세공과 표면에 실리카/고분자를 충전, 피복시켜 투과분리특성을 조사하였다. 현재까지의 연구는 낮은 투과계수와 높은 선택도를 갖는 고분자물질이 사용되었으나, 본 연구에서는 폴리이미드로는 폴리이미드 중에서 투과계수가 가장 높다고 알려진 6FDA-p-TeMPD[{(3,3',4,4'-dicarboxyphenyl)hexafluoropropanedianhydride}-{2,3,5,6-Tetra-methyl-1,4-phenylenediamine}] 폴리이미드를 택하였으며 다공성지지체는 aluminum oxide를 사용하였다 . 본 실험에서는 선택도와 투과속도에 주로 영향을 미치는 폴리이미드와 실리카의 양에 대하여 고찰하였다.

• Journal of Forest and Environmental Science
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• v.23 no.1
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• pp.1-4
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• 2007

The bark of Juglans mandshurica Maxim. was collected, extracted with acetone-$H_2O$ (7:3, v/v), fractioned with n-hexane, $CH_2Cl_2$ and EtOAc, then each fraction was freeze-dried to give some powders. A portion of the EtOAc (28.4 g) fraction was chromatographed on a Sephadex LH-20 column eluting with a series of MeOH-$H_2O$ and EtOH-hexane mixture. Four gallotannins, gallic acid (1), ellagic acid (2), 1,2,4,6-tetra-O-galloyl-${\beta}$-D-glucose (3) and 1,2,3,4,6-penta-O-galloyl-${\beta}$-D-glucose (4), have been isolated from the EtOAc fraction Their structures were elucidated on the basis of chemical evidence and spectrometric analysis such as NMR and MS. The antioxidant activities on each fraction and the isolated gallotannins were evaluated by DPPH radical scavenging test.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2253-2260
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• 2007

A series of tetra donor substituted [2.2]paracyclophane-based two-photon absorption (TPA) fluorophores were synthesized in neutral and cationic forms. The imaging activity of overall set of fluorophores was studied by the two-photon induced fluorescence (TPIF) method in a range of solvents. We also measured a clear progression toward a longer photoluminescence lifetime with increasing solvent polarity (intrinsic photoluminescence lifetime, τi: ~2 ns in toluene → 12-16 ns in water). The paracyclophane fluorophores with this unique property can be utilized as an optical polarity probe for the biomolecular substrates. The combined measurement of the two-photon fluorescence microscopy (TPM) cell image and TPIF lifetime can give us a better understanding of the biological processes and local environments in the cells.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.725-728
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• 2000

The effects of agitation rate and agitation time on the synthesis of sphingosome were studied. As increase in the agitation rates 4,000, 6,000, 8,000, 10,000 and 12,000 rpm the viscosity of sphingosome were decreased. The most sufficient agitation rate was 8,000rpm for which micell viscosity and stability. The effect of agitation time on the sphingosome viscosity and stability was investigated by changing the agitation times 2, 4, 6, 8 and 10 minute at 8,000rpm. 4 minute was the most sufficient for the viscosity and stability. The sphingolipid activity of cutaneous wound healing in impaired mice was examined. As a result, we could prove that phytosphingosine-HCl medically worked on wound healing well. For the phytosphingosine-HCl, it was found that the experimentally determined medical action more effective than that of tetra-acetylphytosphingosine.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.9
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• pp.1398-1405
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• 2015

Domestic railway communication in Korea has been introduced for mutual communications among control center, operation staffs, and maintenance staffs. It has been mainly used as railway disaster and safety functions from VHF and UHF from 1980’s and TRS-Astro and TRS-Tetra from the 2000’s. Recently for urban railways communications, 18GHz and 2.4GHz ranges have been utilized for image transmissions and control command communications, respectively. This paper analyzes technical development of LTE-R, LTE communication for Railways, that has been designed as a single integrated railway wireless network in order to merge the current various communication systems. In this paper, we present the details of the examination of the LTE-R test-bed using 2.6GHz test frequency in Daebul test line through CW test and optimization test.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.205-208
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• 2006

This paper proposes a new computational aeroacoustics method for an axial fan analysis. The major aeroacoustic noise source of an outdoor air-conditioner is the axial fan. It was revealed that the dominant noise source is the aerodynamic interactions between the rotating blade and stationary orifice. Many researches were focused on the fan only case. However, it does not fit to a real outdoor unit of air-conditioner. Especially, the inlet part of the axial fan of real system case is complex and not uniform. So, in order to identify the dominant noise source of axial fan, full outdoor unit analysis is important. Transient CFD analysis of full system was performed by commercial CFD code - SC/Tetra. Dominant noise source of the system was calculated by commercial CFN code - FlowNoise. The results show that not only BPF peaks but also broadband noise are similar to the measured data.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.233-238
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• 2008

An alternator which converts mechanical rotating energy into electric energy is an important component of a vehicle. It operates in broad range from 3000 RPM to 18000 RPM. So, sufficient flow rate and low noise are needed in such broad operating range for a cooling fan of this alternator. In current study, the cooling fan of an alternator is developed through DFSS process and numerical analysis. In order to calculate flow rate and noise level, SC/Tetra and Flow Noise are used respectively, for a new developed fan, compared with original model, numerical result shows 3 dBA reduction and measured value shows 4 dBA reduction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.3
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• pp.186-193
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• 2009

In this article, the effect of silica addition on the phase transformation characteristics of $TiO_2$ nanoparticles synthesized by using an $O_2$-enriched coflow, hydrogen, diffusion flame was investigated. TTIP(titanium tetra-isopropoxide) and TEOS(tetraethyl-orthosilicate) were used as precursors for $TiO_2$ and $SiO_2$ nanoparticles, respectively. Based on the results from TEM and XRD analysis, it is believed that the silica addition on the flame synthesis of $TiO_2$ nanoparticles reduces the particle size distribution and raises the temperature of the phase transition from anatase to rutile. But the reduced sizes of the synthesized particles due to the silica addition made the sintering and phase transformation of particles more easily.

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.65-68
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• 2004

The design procedure for centrifugal blower with high inlet resistance is not presented yet. Overall fluid dynamic performance is estimated for comparison between the case of atmospheric inlet condition and the present model. Detail information between blades is prepared by using a commercial program, SCRYU-Tetra. A centrifugal blower with large inlet pressure is adopted in an air purifier having filtering devices. As the inlet residence increases the flow rate of the system is decreased. In parallel, outlet area of the system affects the performance of the system in the sense of flow balance. Consequently, the flow balance between the inlet and outlet becomes an important parameter for the design of the scroll casing for the centrifugal blower with high inlet pressure.