• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.540-543
• /
• 2000

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li polymer battery. The temperature dependence of conductivity, impedance spectroscopy and electrochemical properties of PAN/PVDF electrolytes as a function of a mixed ratio were reported for PAN/PVDF based polymer electrolyte films, which were prepared by thermal gellification method of preweighed PAN/PVDF, plasticizer and Li salt. The conductivity of PAN/PVDF electrolytes was $10^{-3}$S/cm. $PAN_{10}$$PVDF_{10}$$LiClO_4$$PC_{5}$$EC_{5}$ electrolyte has the better conductivity compared to others. The interfacial resistance behavior between the lithium electrode and PAN/PVDF based polymer electrolyte has also been investigated and compare with that between the lithium electrode and the PAN/PVDF based polymer electrolyte.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.11a
• /
• pp.374-377
• /
• 1999

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li polymer battery. This paper describes temperature dependence of conductivity, impedance spectroscopy, electrochemical properties of PVDF/PAN electrolytes as a function of a mixed ratio. PVDF/PAN based polymer electrolyte films were prepared by thermal gellification method of preweighed PVDF/PAN, plasticizer and Li salt. The conductivity of PVDF/PAN electrolytes was 10-3S/cm. 20PVDF5PANLiCIO$_4$PC$\sub$10//EC$\sub$10/ electrolyte shows the better conductivity of the others. 20P7DF5PANLiCI$_4$PC$\sub$10//EC$\sub$10/ electrolyte remains stable up to 5V vs. Li/Li$\^$+/. Steady state current method and ac impedance used for the determination of transference numbers in PVDF/PAN electrolyte film. The transference number of 20PVDF5ANLICIO$_4$/PC $\sub$10//EC$\sub$10/ electrolyte is 0.48

• Computers and Concrete
• /
• v.21 no.2
• /
• pp.139-147
• /
• 2018

Due to enhanced construction requirement, ready mixed concrete are being popular day by day. The current study aimed to develop ready mixed concrete using GBFS contained cement and determine its properties of fresh and hardened states. A real scale experiment was set up in a ready mixed plant for measuring workability and compressive strength. The workability was tested after mixing (within 5 minutes), 30, 60, 90, 120 and 150 minutes of the running of bulk carrier. The ready mixed carrier employed spinning motion i.e., rotating around its axis with 20 RPM and running on road with 1km/h speed. The mixing ratio of cement: sand:gravel, water to cement ratio, super plasticizer were, 1:1.73:2.47, 0.40 and 6% of cement, respectively. The chemical composition of raw material was determined using XRF and the properties of cements were measured according to ASTM standards. The experimental results confirm that the cement with composition of 6.89% of GBFS, 4% of Gypsum and 89.11% of clinker showed the good compressive strength and workability of concrete after 150 minutes of the spinning motion in bulk carrier.

• The Korean Journal of Ceramics
• /
• v.7 no.1
• /
• pp.16-19
• /
• 2001

For the fast dry of the aqueous tape, the process which water was reaplaced by organic solvent was proposed. Socalled, it was the solvent washing dry. Three organic solvents (methanol, ethanol and acetone) were selected for the washing solvent. The weight loss of the washed tapes was measured to evaluate the dry rate of the tapes and dried tapes were examined the generation of the cracks with the variations of the organic solvent and the washing time. Methanol, ethanol and acetone were available organic solvents for this method. The tapes washed in methanol, ethanol and acetone were dried rapidly for twenty minutes. After thirty minutes, the weight losses were not found any more, The solvent of the lower surface tension can decreases the crack of dried tape. If solvent substitutes water completely, though it was fast dried, crack can be eliminated.

• Computers and Concrete
• /
• v.15 no.2
• /
• pp.215-229
• /
• 2015

The emerging technology of self compacting concrete, fiber reinforcement together reduces vibration and substitute conventional reinforcement which help in improving the economic efficiency of the construction. The objective of this work is to find the regression model to determine the response surface of mix proportioning Steel Fiber Reinforced Self Compacting Concrete (SFSCC) using statistical investigation. A total of 30 mixtures were designed and analyzed based on Design of Experiment (DOE). The fresh properties of SCC and mechanical properties of concrete were studied using Response Surface Methodology (RSM). The results were analyzed by limited proportion of fly ash, fiber, volume combination ratio of two steel fibers with aspect ratio of 50/35: 60/30 and super plasticizer (SP) dosage. The center composite designs (CCD) have selected to produce the response in quadratic equation. The model responses included in the primary stage were flowing ability, filling ability, passing ability and segregation index whereas in harden stage of concrete, compressive strength, split tensile strength and flexural strength at 28 days were tested. In this paper, the regression model and the response surface plots have been discussed, and optimal results were found for all the responses.

• Macromolecular Research
• /
• v.16 no.3
• /
• pp.247-252
• /
• 2008

Lithium gel electrolytes based on a mixed polymer matrix consisting of poly(vinylidenefluoride-hexafluoropropylene) (PVDF-HFP) and cyanoresin type M (CRM) were prepared using an in situ blending process. The CRM used in this study was a copolymer of cyanoethyl pullulan and cyanoethyl poly(vinyl alcohol) (PVA) with a mole ratio of 1:1. The mixed plasticizer was ethylene carbonate (EC) and propylene carbonate (PC) with a volume ratio of 1:1. In this study, the presence of PVDF in the electrolytes helps to form a dimensionally stable film over a broad composition range, and decreases the viscosity. In addition, it provides better rheological properties that are suitable for the extrusion of thin films. However, the presence of HFP has a positive effect on generating an amorphous domain in a crystalline PVDF structure. The ionic conductivity of the polymer electrolytes was investigated in the range 298-333 K. The introduction of CRM into the PVDF-HFP/$LiPF_6$, complex produced a PVDF-HFP/CRM/$LiPF_6$ complex with a higher ionic conductivity and improved thermal stability and dynamic mechanical properties than a simple PVDF-HFP/$LiPF_6$, complex.

• Journal of the Korean Geosynthetics Society
• /
• v.14 no.3
• /
• pp.13-20
• /
• 2015

Inappropriate backfill material and poor compaction cause the damage to sewer and ground settlement. To deal with such problem, flowable backfill material has attracted attention recently. A basic study was conducted in a bid to obtain optimum mixing ratio of backfill material with the characteristics of rapid hardening, pseudo-plasticity, flowability and anti washout ability and enhance the cost efficiency of backfill material. Through the test of optimal mixing ratio of rapid hardening, evaluation of optimal mixing ratio of backfill material was conducted. As a result, required performance as well as cost efficiency could be achieved by adjusting plasticizer even in case of increasing W/M of the paste of rapid hardening to 100%.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.20 no.5
• /
• pp.1-8
• /
• 2016

This paper presents an evaluation of engineering properties in TDFA(Tire Derived Fuel Ash)- based concrete in early age. Concrete containing 0.5 of w/b(water to binder) ratio and 20% of FA(Fly Ash) replacement ratio are prepared, and FA content are replaced with TDFA from 3% to 12% for evaluating the effect of TDFA on fresh and hardened concrete properties. With higher than 6% of TDFA replacement ratio, workability is significantly worsened but it is improved with more SP(Super plasticizer) and AE(Air Entrainer) agent. Concrete with 6~12% of TDFA shows reasonable strength development and better resistance to carbonation and chloride attack in spite of early-aged condition. However concrete with 6% TDFA shows poor resistance to freezing and thawing action due to insufficient air content. If air content and workability are obtained, replacement of TDFA to 12% can be used for concrete with FA.

• Magazine of the Korea Concrete Institute
• /
• v.7 no.3
• /
• pp.149-155
• /
• 1995

An experimental study was carried out to investigate the strength implovlng effect of stone dust in no fines concrete. The cement aggregate ratios of 1:6, 1:8 and 1:10 and several water-cemment ratios between 30% and 56% were chosen for the mix design of no-fines concrete. For the no-fines concrete with stone dust, the weight ratio of cement to stone dust 1:1 was adopted and super plasticizer, 1.5% of cement in weight, was used to obtain proper and workable state of concrete. The compressive and tensile strength test were performed and the results for the different mix designs were compared with each other. The results show that the compressive strength of no-fines concrete can be improved by 38% and the tensile strength by 17%~72% for the same w/c, when the same weight of stone dust as cement is mixed together.

• Journal of Biosystems Engineering
• /
• v.27 no.3
• /
• pp.249-258
• /
• 2002

The fourteen different electrodes coated with polymeric lipid membrane were evaluated to selectively monitor the sweet, salty, sour and bitter tastes, and umami. The polymeric lipid membrane consisted of the three components, or polymer matrix, plasticizer and electroactive material, the compositional ratio of which was 1:1.25:1. Herein, the 14 different electroactive materials were used. Sucrose, NaCl, citric acid, caffeine and MSG were used as standard materials of sweet, salty, sour and bitter tastes, and umami. The linear responses of each electrode regarding 5 tastes were analyzed by means of the correlation coefficient between electric potential difference and concentration of a taste material when the linearity was based on a linear model and a thermodynamic model, respectively. As fur salty taste, the electrode coated with valinomycin had a selective linearity at the significance level of 0.01. For monitoring sweet taste, the electrode with oleylamine and the electrode with the mixture of tai-n-octylmethylammonium chloride and dioctylphosphate (2:8) showed the significant linearities at the levels of 0.05 and 0.10, respectively.