• 한국표면공학회지
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• 제20권1호
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• pp.4-14
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• 1987

The nickel-zinc alloy depositions have been studied in nickel chloride added chloride baths, to find out the effects of ultrasonic irradiation for the electrodeposition processes. The compositions of deposited alloys, the current efficiencies and the metallographic appearances in various conditions of Electrodeposition were investigated, in the range of ultrasonic irradiation of 50,500 and 1,000 Kc/s respectively. The results obtained are as follows; 1. Generally the nickel deposition process is more preferably activated than that of zinc by the ultrasonic irradiation. 2. The radios of nickel to zinc in the deposit are higher according to increase of nickel ion concentration and bath temperatures in irradiated baths. 3. The current efficiencies are also higher in the irradiated baths, so that the depolarization effect is noticeable. 4. The brightness and leveling effect of the deposits are appreciably better in the irradiated baths than in non-irradiated in 0.3M and 0.6M of nickel chloride and zinc chloride solutions and the current density of 3A/$dm^2$. 5. The mechanism of alloy deposition has been tentatively suggested in the case of ultrasonic irradiation.

• Membrane and Water Treatment
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• 제6권1호
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• pp.43-52
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• 2015

A small-scale electro-dialysis system was constructed for domestic use. It is composed of six compartments in which five special polystyrene ionic membranes are housed. A series of experiments on the transport of sodium and chloride ions through polystyrene membranes was performed and the effects of electric current and voltage on the pH of water were investigated. This electrodialyser could reduce the NaCl content to an acceptable level (5307 mg/L) when water containing 9945 mg/L of sodium chloride is fed to the electrodialyser. The reduction was by the action of direct current 60 mA/100 mA when a 15 V / 20 V potential is maintained across the membrane. The results showed that the pH of the treated water attained a value in the range of 7-8, with the chloride concentration of 5307 mg/L when the voltage was in the range of 20 volts. This was achieved when two of the small-scale electro-dialysers were placed in series and the solutions from the respective compartments were mixed. This is considered useful because this complies to the requirement of drinking water standard both in terms of chloride and pH. Therefore, this type electrodialyserhas the potential for domestic uses in isolated houses where potable water supply is not available.

• Membrane and Water Treatment
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• 제3권2호
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• pp.123-131
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• 2012

This study investigated the extraction and stripping performance of PIMs consisting of PVC and Aliquat 336. Extraction and stripping of three representative heavy metals - namely $Cd^{2+}$, $Cu^{2+}$, and $Zn^{2+}$ - by the synthesized membranes were evaluated as a function of sodium chloride concentration and under different stripping solutions (0.01 M $HNO_3$, Milli-Q water, 0.01 M HCl and 0.01 M NaOH), respectively. Results reported here indicate that the formation of negatively charged metal chloride complex species was responsible for the extraction of the target metal to PIMs. Experimental results and thermodynamic modeling of the speciation of chloro metal complexes further confirm that the extraction selectivity between $Cd^{2+}$, $Cu^{2+}$ and $Zn^{2+}$ can be controlled by regulating the chloride concentration of the feed solution. An acidic solution without any chloride was the most effective stripping solution, followed by Milli-Q water, and a diluted hydrochloric acid solution. On the other hand, the stripping of metals from PIMs did not occur when a basic stripping solution was used.

• Korean Chemical Engineering Research
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• 제52권4호
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• pp.436-442
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• 2014

염화코발트 용액을 사용하여 전자기파와 진동에 영향을 받지 않는 원거리 실시간 광섬유 온도 감지 센서를 개발하였다. 염화코발트 용액을 제조하기 위하여, 물과 에탄올은 부피 비율로 10%와 90%로 고정하고, 용해되는 염화코발트의 양을 다양하게 변화시켰다. 제조된 염화코발트 용액은 자외-가시선 분광 광도계를 사용하여, 온도 변화에 따른 655 nm 파장의 투과도를 측정하였다. 또한 제조된 30.8 mM 염화코발트 수화물 용액에 polyvinyl butyral을 용해시켜 겔화한 후, 온도 변화에 따른 655 nm 파장의 투과도 측정 및 센서 적용 후 광 파워 분석을 실시하였다. 투과도와 광 파워 측정 결과, $25^{\circ}C$에서 66.8%와 149.5 nW, $70^{\circ}C$에서는 7.1%와 48 nW로 각각 나타나, 온도가 증가함에 따라 투과도와 광 파워 모두 감소하는 경향을 보였다. 본 실험에서 제조된 겔화 염화코발트/polyvinyl butyral은 온도 변화에 따라 655 nm 파장에 대한 광 투과도와 광 파워가 변하는 점을 이용하여 온도 변화를 감지하기 위한 광섬유 센서로 사용 가능함을 확인하였다.

• 한국전자파학회논문지
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• 제29권4호
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• pp.247-255
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• 2018

본 논문에서는 complementary split ring resonator(CSRR)을 이용하여 마이크로파 대역에서 비침습적으로 포도당 수용액과 염화나트륨 수용액을 구별하였다. 개방형 동축 프로브로 측정한 두 수용액의 전기적 특성을 기반으로 구별이 유리한 주파수에서 동작하는 CSRR을 설계, 제작하였다. 그리고 공진기의 전기장이 강하게 형성되는 부분에 수용액을 집중시키기 위해 PDMS mold를 제작하였고, 라미네이트 필름으로 수용액과 공진기의 접촉을 방지하였다. 두 수용액의 농도는 인체 혈당 농도 범위인 400 mg/dL까지 100 mg/dL 단위로 나누었고, $50{\mu}L$의 수용액으로 실험하였다. 공진 주파수에서 포도당 수용액과 염화나트륨 수용액의 투과계수($S_{21}$)를 측정한 결과, 100 mg/dL 농도 변화 대비 각각 -0.06 dB, 0.14 dB 변하는 것을 확인하였고, 상반된 경향을 통해 두 수용액의 농도에 따른 $S_{21}$의 변화를 선택적으로 구별하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 봄 학술발표회 논문집
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• pp.396-401
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• 1995

Epoxy coated reinforcing steels (ECRs) were acquired from ten sources and coatings from each source were initially characterized in terms of defects, thickness, solvent extraction weight loss and hardness. Testing involved exposure in three aqueous solutions at elevated temperature (8$0^{\circ}C$) and in chloride-contaminated concrete slabs under outdoor exposure, It was found that the density and size of coating defects was the promary factor affecting ECR performance. The equivalent circuit analysis using electrochemical impedance spectroscopy (EIS) data indicated that the impedance response for well-performing ECR specimens showed no signs of active degradation at the interface although diffusional processes similar to those noted for poorly performing bars occurred here. Experimental results also indicated a relationship between corrosion behavior and bar source. Weight loss upon solvent extraction correlated with impedance reduction from hot water exposure. Coating defects during most of the tests, especially in high pH solutions containing chloride ions. ECRs with excessive coating defects, either initially present or ones which developed in service, performed poorly in every test category regardless of source. Forms of coating failure were extensive rusting at defects, blistering, wet adhesion loss, cathodic delamination, underfilm corrosion and coating cracks. These occurred sequentially or concurrently, depending on the condition of the ECR and nature of the environment

• 한국응용과학기술학회지
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• 제19권4호
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• pp.339-348
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• 2002

Self-diffusion coefficients of colloidal ass9Ciation structures in the aqueous solutions of anionic ammonium dodecyl sulfate (ADS) and cationic octadecyltrimethylammonium chloride (OTAC) surfactants were measured by pulsed-gradient spin echo NMR. The results were interpreted on the basis of the ADS/OTAC/water phase diagram. Crossing the phase boundaries, significant changes in self diffusion coefficients were observed and well correlated to the phase diagram. For the micelles their apparent radii were obtained from Stokes-Einstein equation. Their values were 15 for the ADS micelles and 54 ${{\AA}}$ for the OTAC micelles, respectively. For vesicles which were formed spontaneously at different relative amounts of the surfactants and total surfactant concentrations, the radius was measured as 50 to 200 nm. This result is in fair agreement with those by TEM and light scattering.

• 한국응용과학기술학회지
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• 제25권1호
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• pp.23-31
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• 2008

In general, anionic and cationic surfactants are incompatible because their mixtures form insoluble complexes. There are, however, some complexes that are soluble and behave like regular surfactants, specifically like nonionic surfactants, thus named pseudo-nonionic surfactant complexes. Pseudo-nonionic complexes are more effective and efficient than their ionic surfactant components as shown by their equilibrium and dynamic surface tensions and interfacial tensions. They pack at the interface more than their ionic components. Since, pseudo-nonionic complexes show their own characteristics, they can be treated as separate classes of surfactants distinct from ionic and nonionic surfactants. Novel cationic surfactant was synthesized, having the polyhydroxyl group at the head group. We found that aqueous mixtures of our cationic surfactant and usual anionic surfactant(SDS) could form homogeneous solutions even at high concentration. The properties of mixed surfactant solutions were measured. Foam stability, CMC(critical micelle concentration), water hardness tolerance and thickening effect were tested. The foam stability of mixed surfactants was very good and various synergy effects were observed.

• 한국분말재료학회지
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• 제10권4호
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• pp.228-234
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• 2003

In the present study, the focus is on the synthesis of titanium carbide/cobalt composite powder by the spray thermal conversion process using metallic salt solution as the raw materials. Two types of oxide powders of Ti-Co-O system were prepared by the spray drying of two types of metallic salt solutions : titanium chloride-cobalt nitrate and $TiO_2$ powder-cobalt nitrate solutions. These oxide powders were mixed with carbon black, and then these mixtures were carbothermal reduced under a flowing argon atmosphere. The changes in the phase structure and thermal gravity of the mixtures during carbothermal reduction were analysed using XRD and TG-DTA. In the case of using the titanium chloride-cobalt nitrate solution, it could not be obtained TiC/Co composite powder due to contamination of the impurities during the spray drying of the solution. However, in tile case of using the $TiO_2$ powder-cobalt nitrate scullion, TiC-15 wt. %Co composite powder could be synthesized by the spray thermal conversion process. The synthesized TiC-15 wt. %Co composite powder at 120$0^{\circ}C$ for 2 hours has average particle size of 150 nm.

• 한국응용과학기술학회지
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• 제13권1호
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• pp.87-98
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• 1996

In this study, benzoxazolo carbocyanine dye was used as sensitizer for photographic emulsion, and the photographic characteristics were examined. The basic properties of sensitizer such as stability in various solvents were examined. The sensitizer was very stable in methanol, acetonitrile, acetone, dimethylformamide, and chloroform solution. Absorption spectra of benzoxazolo carbocyanine dye $2.5{\times}10^{-6}M$ and $5{\times}10^{-6}M$ concentrations in 10% aqueous methanol solutions containing $10^{-2}M$ potassium chloride show the monomer-J-aggregation characteristics. Compared to the absorption peak of the monomer in pure methanol solution, the red shifts of the monomer-J-aggregate peaks of benzoxazolo carbocyanine dye of $2.5{\times}10^{-6}M$ and $5{\times}10^{-6}M$ concentrations in 10% aqueous methanol solutions containing $10^{-2}M$ potassium chloride are 34nm respectively, and the sensitizing peak of benzoxazolo carbocyanine dye in photographic emulsion has red shift of 34nm. Therefore, if was concluded that benzoxazolo carbocyanine dye can be used as green sensitizing dye for the spectral sensitization of photographic emulsion.