• 한국응용과학기술학회지
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• 제25권2호
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• pp.205-210
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• 2008

The transformation of the liquid crystal complex made by binding of anionic surfactant, sodium dodecyl sulfate (SDS), into high charge density cationic polymer, the homopolymer of diallyldimethylammonium chloride (PDADMAC) was induced by adding of nonionic surfactants and investigated by means of microscopy and FE.SEM. Among nonionic surfactants in this experiments polyethylene glycol (3 mol) ether of lauryl alcohol (laureth-3) made variation in the complex. The laureth-3 transformed the complex into spherulite vesicle with the size of ca.$100{\mu}m$. This change increased the viscosity and the turbidity of the solution phase separated originally. Microscope showed that they are spherulite particles and polarized microscope suggested they are multi.lamellar liquid crystals. FE-SEM also proved that explicitly.

• 한국광학회:학술대회논문집
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• 한국광학회 2001년도 제12회 정기총회 및 01년도 동계학술발표회
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• pp.206-207
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• 2001

The photorefractive (PR) effect in liquid crystals sandwiched between photoconductive polymer layers was first studied by Ono et al. They reported that the PR effect vanished at steady state If there were not insulating layers because no charge trapping occurred in the photoconductive poly(N-vinylcarbazole) (PVK) layers. However we observed a significant PR effect in the polymer layered liquid crystal (PLLC) system where a liquid crystal layer doped with fullerene is sandwiched between two photoconductive PVK layers. (omitted)

• 조명전기설비학회논문지
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• 제25권8호
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• pp.39-47
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• 2011

The motion of a conductive spherical particle under uniform electric field is investigated in order to find a suitable method for removing the conducting solid impurities contained in liquid plastic. When the positive dc voltage applied to the upper electrode, the vertical up-and-down motion of a charged particle by electrostatic force is observed by a charge-coupled device (CCD) camera or a high-speed video camera. The experimental data of the static threshold voltage by which the particle starts to move toward the counter electrode in air or silicone oil are in good agreement with theoretical value. When the applied voltage is larger than the static threshold voltage, the particle motion pattern in silicone oil consists of four stages: upward motion, stopping at the upper electrode, downward motion and stopping at the lower electrode. The stopping motion on the electrode is thought to be caused by the liquid flow accompanied by the particle motion. The particle charge calculated by integrating the pulse current, which is generated by the charge exchange between the electrode and the particle, is approximately 0.1~0.25 times of the theoretical value. This study is expected to help understand the electric properties of microparticles in oil circuit breaker (OCB) and oil transformer and improve their performance and longevity.

• 청정기술
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• 제20권4호
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• pp.354-358
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• 2014

이온성 액체는 상온에서 액체로 존재하는 이온성염으로 최근 청정 공정에 사용될 수 있는 용매, 전해질, 촉매로써 주목받고있다. 본 연구에서는 비전도성 매질 내 액적의 접촉 충전 현상을 이용하여 여섯 가지 서로 다른 이온성 액체에 대한 충전 거동을 고찰하였다. 이온성 액체 액적의 충전 현상은 이전 수용 액적의 충전 현상과 유사한 특징을 나타내었으며 기본적으로 완전 도체 이론으로 설명이 가능하였다. 하지만 이온 종류에 따른 상세 거동은 다소의 변화가 관찰되었다. 본 연구의 결과는 청정 용매 및 촉매로 각광 받고 있는 이온성 액체의 전기화학적 특성을 이해하고 분석하는데 유용하게 활용될 수 있을 것으로 기대된다.

• Journal of Advanced Marine Engineering and Technology
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• 제31권5호
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• pp.558-566
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• 2007

The performance characteristics of water-chilling heat pump using $CO_2$ with respect to variation of refrigerant charge amount was investigated experimentally. An experimental apparatus is consisted of a compressor, a gas cooler, an expansion valve, an evaporator and a liquid receiver. All heat exchangers used in the test rig are counter-flow-type heat exchangers with concentric dual tubes, which are made of copper. The gas cooler and the evaporator consist of 6 and 4 straight sections respectively arranged in parallel, each has 2400 mm length. The experimental results summarize as the followings : As the refrigerant charge ratio of $CO_2$ heat pump system increases, the discharge pressure and compressor ratio increases, but mass flow rate of refrigerant decreases. Also the compressor work increases with the increase of refrigerant charge ratio. However, the heating and cooling capacity of $CO_2$ heat pump decreases as the refrigerant charge ratio increases. The maximum heating COP of $CO_2$ heat pump system presented at 0.25 refrigerant charge ratio. It is possible to confirm the optimum charge ratio of $CO_2$ heat pump system by the viewpoint of heating COP.

• 대한기계학회논문집B
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• 제26권8호
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• pp.1102-1114
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• 2002

An electret filter is composed of permanently charged electret fibers and is widely used in applications requiring high collection efficiency and low-pressure drop. In this work, the collection efficiency of the filter media used in manufacturing cabin air filters was investigated by using poly-disperse particles when submicron particles were loaded. Long-term experiments were conducted by applying two different charging states, which were spray electrification and charge equilibrium by bipolar ionization. In order to investigate the effect of particle loading in filter media, NaCl particles were generated from 0.1% and 1% solutions by an atomizer. Liquid DOS particles were used to evaluate the effect of liquid particles on the collection efficiency of an electret filter. The results show significant effect of charge amount and size distribution of loading particles on the collection performance of a filter media in submicron region. Smaller particles loaded in electret fibers cause a more rapid degradation in collection efficiency and have lower minimum efficiency with time. The pressure drop of a filter media do rarely increase when the collection efficiency decreases to the minimum value. For the larger particles charged by spray electrification, which have charge amounts more than that of Boltzmann equilibrium charge distribution, the pressure drop of a filter media slowly increases in comparison with that of equilibrium charged particles. For DOS particles it is shown that the charging level of an electret filter severely decreases and the collection efficiency is below 10% in some particle size range.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.228-230
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• 2008

The response time characteristic of low voltage liquid crystals (LCs) is investigated and a new simulator for low voltage LCs is proposed. In order to enable low voltage operation, it is important to minimize Vth of LCs and variation of pixel voltage caused by dynamic capacitance operation of LC Display. Because dynamic capacitance variation is much larger for low voltage LC operation compared to that of conventional LC material, it is necessary to make a better model for dynamic capacitance operation. A proposed minimizing Vth of LCs and variation of pixel voltage study results through a new constant charge model improve response characteristics for low voltage LCs operation.

• 한국자동차공학회논문집
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• 제10권1호
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• pp.106-114
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• 2002

In this study, the air-fuel ratio(A/F) control characteristics of a liquid and a gaseous fueled engine are investigated. Engine models far both the liquid and the gaseous fueled engine are developed to compare the characteristics of fuel delivery into the cylinder, and the performances of the models are evaluated using the simulation and experiment. The simulation and experimental results show that the gaseous fueled engine has better control performance than that of the liquid fueled engine in terms of the air-fuel ratio control. This study could be used to develop air-fuel ratio control schemes for both the liquid and the gaseous fueled engine.

• 한국건축시공학회지
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• 제3권1호
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• pp.115-122
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• 2003

In order to analyze liquidity change according to increasing the charge of superplasticizer, we inputted charges by dividing into six steps, 0% through 1.25%; at the same time, to observe liquidity change according to the change of charge-time, we carried out the experiment applying 30-minute intervals, i.e. at beginning of mixing, 30, 60 and 90 minutes. The results are below. 1) According to increasing the charge of superplasticizer, the liquidity of concrete was enhanced, however, when inputted 1.25%, a little segregation was occurred, which allowed us to make a conclusion that concrete performance would be deteriorated due to this segregation. 2) When we inputted 1.25% of superplsticizer, steady liquidity features were shown regardless of the charge-time of concrete, which allowed us to make a conclusion that this input would be the best for liquidity performance considering only liquidity features. 3) After analyzing the dynamical features of liquid concrete, the result showed that there was not significant effect on revelation of compressive strength. We concluded form this result that there was no influence on the stripping-time of a mold form. 4) When we charge superplasticizer in concrete more than 1%, we, in advance, should clearly judge the concrete performance required during constructing in site, as it were, the compressive strength or liquidity etc.; furthermore, we had better decide a charge and input-time of superplasticizer to meet the required performance.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1997년도 Proceedings of the 12th KACG Technical Meeting and the 4th Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.253-259
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• 1997

The iron doped GaAs single crystals were grown by liquid phase epitaxial method and its some physical properties were evaluated with a view to investigate the crystal quality and emission property. The isomer shift of 0.303mm/sec is calculated from low-temperature M ssbauer spectroscopy and we know that charge state of iron ion is 3+ in GaAs crystal. In low temperature photoluminescence, the deep emission bands with wide-line width have been observed at 0.99eV and 1.15eV in addition to sharp excitonic peaks. We attributed that these deep emissions are originated from substitutional Fe-acceptor which has charge state of 3+ and 2+, respectively.