• 한국통신학회논문지
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• 제33권11B호
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• pp.989-997
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• 2008

The reverse acknowledgment (RA) scheme supports a fast loss recovery for negative acknowledgment (NAK)-based selective repeat automatic repeat request (SR-ARQ) by detecting a retransmission failure quickly before a retransmission timer expires. In this paper, we evaluate the performance of a NAK-based SR-ARQ protocol with the RA scheme and compare it with the conventional NAK-based SR-ARQ protocol. Particularly, we propose a simple analysis model for the transport delay of the NAK-based SR-ARQ protocol considering the traffic condition, the retransmission persistence, the timer-based retransmissions and the RA scheme's behavior. Both NAK-based SR-ARQ protocols with and without the RA scheme are implemented by using the OPNET simulator. We verified the analysis model's accuracy through the simulation results. Also, we evaluate the performance of the NAK-based SR-ARQ protocol with the RA scheme based on analysis and simulation results.

• 청정기술
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• 제6권2호
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• pp.129-137
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• 2000

역수성가스반응과 메탄올형성반응을 연계한 메탄올합성공정에 대한 엑서지 해석을 수행하였다. 실험자료를 이용하여 공정을 모사하였으며 공정모사의 결과를 이용하여 엑서지 해석을 수행했다. 구동엑서지 손실과 물질엑서지 손실을 각각 정의하였고 정량화 하였다. 해석결과를 바탕으로 엑서지 손실의 위치, 크기, 원인과 개선 가능방법 등을 제시하였다. 엑서지 해석은 오염방지를 위한 손실예방책을 발전시키고 나아가 산업생태학에 적용할 수 있는 타당한 과학적 근거가 될 수 있음을 알 수 있었다.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 춘계 총회 및 학술발표회
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• pp.82-85
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• 2004

Flux-enhancement mechanism of thin-film-composite (TFC) membranes for the reverse comosis (RO) process was newly explained by positron annihilation lifetime spectroscopy (PALS) that has been found to be applied for detecting molecular vacancies or pores having sizes that are equivalent to salt or hydrate ions in RO membrane.(omitted)

• 한국CDE학회논문집
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• 제11권4호
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• pp.265-272
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• 2006

For the design and analysis of 3D object featuring complexity and irregularity in shape, sectional digital images measured by an industrial CT scanner are employed to generate a finite element model with uniform voxels. The voxel model plays a key role in developing an integrated reverse engineering system including geometric modeling, simulation and optimization. Design examples applied to topology optimization show that the proposed approach can provide a remarkable reduction in time cost at the conceptual and detail design stages.

• 대한화장품학회지
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• 제23권3호
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• pp.161-167
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• 1997

Determination of several cationic surfactants in cosmetics has been investigated. Reverse phase ion pair chromatography was used to identify and quantitate cationic surfactants. Cationic surfactants analyzed in this experiment were cetylpyridium chloride, stearyltrimetylammonium chloride, bezalkonium chloride, benzyldicethylcetylammonium chloride, and bihenyltrimethyl ammonium chloride. The separation was achieved on a reverse phase coumn with 10mM HCl-acetonitrile eluent. In this condition, the most of cationic surfactants with exception of CPC and CTAC respectively with suppressed conductivity detector and UV detector connected in series. The calibration curves obtained by plotting the peak areas of the cationic surfactants were linear at levels ranging from 0.005 to 0.1% correlation coefficient, r=0.9988. The detection limits were 1 to 5ppm in sample solution. The average recoveries of cationic surfactants added to hair treatment cream and hair rinse in three to five experiments were 96.7 105.2% and relative standard deviations were 1.1-3.8%. The case that there were CPC and CTAC in same solution was also tested. CPC and CTAC which couldn't be separated on reverse phase column were quantitated with suppressed conductivity detector and UV detector connected in series. Recovery of CPC and CTAC were 101.6 and 89.2% respectively. The proposed method was applied to the determination of cationic surfactants in commercial hair treatment cream.

• BMB Reports
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• 제45권3호
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• pp.165-170
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• 2012

We report here that an ethanol extract of Tetracera scandens, a Vietnamese medicinal plant, has anti-HIV activity and possesses strong inhibitory activity against HIV-1 reverse transcriptase (RTase). Using a MT-4 cell-based assay, we found that the T. scandens extract inhibited effectively HIV virus replication with an $IC_{50}$ value in the range of 2.0-2.5 ${\mu}g$/ml while the cellular toxicity value (CC50) was more than 40-50 ${\mu}g$/ml concentration, thus yielding a minimum specificity index of 20-fold. Moreover, the anti-HIV efficacy of the T. scandens extract was determined to be due, in part, to its potent inhibitory activity against HIV-1 RTase activity in vitro. The inhibitory activity against the RTase was further confirmed by probing viral cDNA production, an intermediate of viral reverse transcription, in virus-infected cells using quantitative DNA-PCR analysis. Thus, these results suggest that T. scandens can be a useful source for the isolation and development of new anti-HIV-1 inhibitor(s).

• 한국산업정보학회논문지
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• 제20권2호
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• pp.97-111
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• 2015

본 연구에서는 특정 D 광역시를 대상으로 생활폐기물 처리과정에 대한 역물류(Reverse logistics: RL)네트워크를 구성하고 이를 효율화하기 위한 방법론을 개발했다. 현재 D 광역시에 속한 8개 기초자치단체들은 각 기초자치단체별로 자체적인 RL네트워크를 구성하여 생활폐기물을 처리하고 있다. 그러나 현재와 같은 방법은 운영상의 비효율적인 측면이 있으며, 이를 개선하기 위해 새로운 개선방안을 마련했다. 사례연구에서는 D 광역시 8개 기초자치단체에서의 운영자료를 기초로 하여 기존운영방식과 개선방안에 대한 비교분석을 실시하였으며, 그 결과 개선방안이 기존운영방식보다 더 효율적이라고 분석되었다.

• 상하수도학회지
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• 제24권6호
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• pp.735-741
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• 2010

A pilot test was carried out to investigate the long term operation characteristics of Microfiltration (MF) system as a pretreatment for seawater reverse osmosis (SWRO) processes for two years. A commercialized MF module with pressurized operation type was used to filter seawater to remove particles which can foul reverse osmosis (RO) membrane. Silt Density Index (SDI) values of filtered seawater by the MF system were ranged from 0.14 to 1.79, which meet the SDI standard for RO feed water as depicted in previous literatures. Although the tested seawater is quite clean (i.e., dissolved organic cabon (DOC) concentration and turbidity were about 1 mg/l and less than 1 NTU, respectively) enough not to foul the MF membrane, steep increase in trans-membrane pressure (TMP) with a constant flux were observed over a whole operation period. A set of operation and water analysis data implies that the steep increase in TMP was resulted from iron and maganese fouling by the combination of metal corrosion by seawater and oxidation state by aeration and residual chlorine.

• 열처리공학회지
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• 제12권4호
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• pp.313-319
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• 1999

The reverse transformation behavior was investigated by DSC analysis in thermomechanically processed Fe-30%Ni-0.35%C alloy. Upon increasing the heating rate from $5^{\circ}C/min$ to $80^{\circ}C/min$, the As point of the ausformed martensite was not changed and the As point of the marformed martensite decreased at reverse transformation. The Af points showed to be constant with increasing the heating rate both in the ausformed martensite and in the marformed martensite. With increasing the deformation degree, the As points of the ausformed martensite and the marformed martensite increased and the Af points appeared to be constant, structures. The enthalpy changes increased with increasing the heating rate, but decreased with increasing the deformation degree in both structures.

• 멤브레인
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• 제4권3호
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• pp.142-151
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• 1994

역삼투 공정을 농축공정에 이용하기 위해 향류식 역삼투 나권형 모듈을 고안, 제작하여 염수의 농축실험을 수행하였다. 역삼투 분리의 배제도와 농축도의 관계를 고찰한 결과, 배제유량에 대한 투과유량의 비가 양쪽 관계의 중요한 매개 변수이며, 반사계수 값에 따라, 역삼투막의 배제도와 농축도가 Spiegler-Kedem 식의 경향을 따른다. 향류식 역삼투 공정은 일반 역삼투 농축 공정에 비해 농축의 장애 요소인 삼투압차를 효과적으로 저하시키는 효과가 있으며 농축도가 상대적으로 우수하였다. 향류식 나권형 모듈의 수치모사 결과 농축공정의 농축도 증가를 위해서는 모듈의 지름보다 모듈의 길이를 늘리는 것이 유리함을 알 수 있었다.