• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.701-709
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• 1992

Silver particles were impregnated on carbon black with colloidal method and used as catalyst for oxygen electrode in alkaline fuel cell. With the addition of sodium dodecylbenzenesulfonate in $AgNO_3$ and $NaBH_4$solution, colloidal solution was made and confirmed with electrophoresis test. Effects of particle size on electrode performance were studied and $200{\AA}$ of silver particle size shown the highest value of mass activity. The aggromeration of silver particle was Influenced with surfactant amount, stirring time and heat treatment. Considering the increase of particle size caused of operating temperature, recommendable particle size of silver catalyst for manufacturing the electrode was $100{\AA}$. Dispersity of carbon black was investigated and reagglomeration was appeared after homogenizing 30 sec.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.617-626
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• 2020

The drilling mud is essentially used in oil and gas development. There are several roles of using the drilling mud, such as cleaning the bottomhole, cooling and lubricating the drill bit and string, transporting the cuttings to the surface, keeping and adjusting the wellbore pressure, and preventing the collapse of the wellbore. The fragments from rocks and micro-sized bubbles generated by the high pressure are mixed in the drilling mud. The systems to separate those mixtures and to keep the uniformly maintained quality of drilling mud are required. In this study, the simulation is conducted to verify the performance of the mud tank's agitation capacity. The primary role of the mud tank is the mixing of mud at the surface with controlling the mud condition. The container type is chosen as a mud tank pursuing efficient transport and better management of equipment. The single- and two-phase simulations about the agitation in the mud tank are performed to analyze and identify the inner flow behavior. The convergence of results is obtained for the vertical- and axis-direction velocity vector fields based on the grid-dependency tests. The mixing time analysis depending on the multiphase flow conditions indicates that the utilization of a two-stepped impeller with a smaller size provides less time for mixing. This study's results are expected to be utilized as the preliminary data to develop the mixing and integrating equipment of the onshore drilling mud system.

• Journal of Soil and Groundwater Environment
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• v.13 no.5
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• pp.81-87
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• 2008

In accompany with the transfer of US army bases, recent surveys reported serious contamination of soils by the release of petroleum from storage facilities and heavy metals accumulated in rifle-ranges. These problems have made an increased concerns of cleanup technology for contaminated soils. In this study, a full-scale soil washing process improved by multistage continuous desorption and agitational desorption techniques was examined for petroleum-contaminated soils obtained from three different remedial sites that contained 29.3, 16.6, and 7.8% of silt and clay, respectively. The initial concentrations of total petroleum hydrocarbon (TPH) were 5,183, 2,560, and 4,860 mg/kg for each soil. Pure water was applied to operate washing process, in which water used for washing process was recycled 100% for over 6 months. The results of full-scale washing tests showed that the TPH concentrations for soils (> 3.0 mm) were 50${\sim}$356 mg/kg (85.2${\sim}$98.2% removal rates), regardless of the contents of silt and clay from in A, B and C soil, when the soils were washed at 3.0 kg/$cm^2$ of injection pressure with the method of wet particle separation. Based on the initial TPH concentration, the TPH removal rates for each site were 85.2, 98.2 and 89.9%. For soils in the range of 3.0${\sim}$0.075 mm, the application of first-stage desorption technique as a physical method resulted 834, 1,110, and 1,460 mg/kg of TPH concentrations for each soil, also additional multi-stage continuous desorption reduced the TPH concentration to 330, 385, and 245 mg/kg that were equivalent to 92.4, 90.6, and 90.1% removal rates, respectively. The result of multi-stage continuous desorption for fine soil (0.075${\sim}$0.053 mm) were 791, 885, and 1,560 mg/kg, and additional agitation desorption showed 428, 440, and, 358 mg/kg of TPH concentrations. Compared with initial concentration, the removal rates were 92.0, 93.9 and 92.9%, respectively. These results implied we could apply strategic process of soil washing for varies types of contaminated soils to meet the regulatory limit of TPH.

• Journal of the Korean Applied Science and Technology
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• v.34 no.3
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• pp.545-554
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• 2017

This study is concerned with the stability of liquid crystal forming emulsifier with localized depend on change of pH using liquid crystal forming agent of advanced company. The liquid crystal emulsifying agent was localized using Sugar Crystal-LC (bio-tech Co., Ltd., Korea), and comparative samples were measured by using Nikkomulese-LC (Nikko Camicarls, Japan) and Alacel-LC (Croda Camicarls, UK). Liquid crystal formation was confirmed microscopically to show the formation of liquid crystal structure at acidic (pH=4.2), neutral (pH=7.0) and alkaline (pH=11.7). The particles of the liquid crystal were observed with a polarizing microscope according to the stirring speed. The stirring time was all the same for 3 minutes with a homo-mixer, and the stirring speed was increased to 2500 rpm, 3500 rpm and 4500 rpm to observe the liquid crystal state. As a result, it was found that the Korean surfactant was more stable and clear liquid crystal structure was formed than the two foreign acids. In the case of the UK in acid zone, the emulsion particle size was uniform and unstable. In the case of Japanese surfactant, it has similar structure and performance to those of localized Korean. It was found that Korean surfactant had superior emulsifying performance in acid zone compared with foreign products. It is possible to develop various formulations such as liquid crystal cream, lotion, eye cream, etc. using Sugar Crystal-LC emulsifier as an application cosmetic field, and it is expected that it can be widely applied as emulsifying technology for skin care external application in the pharmaceutical industry and the pharmaceutical industry as well as the cosmetics industry.

• Journal of Mushroom
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• v.16 no.4
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• pp.250-256
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• 2018

The windrow turner, widely used for outdoor fermentation of mushrooms in Europe, has been improved by using rice straw instead of wheat straw in accordance with Korea's actual situation. It was compared with conventional excavator work, and the results were as follows. Agitation performance was $81m^3/hr$, which was 2.8 times higher than $28.6m^3/hr$ of excavator. As a result of the temperature distribution in the pile at the end of the fermentation stage, it was found that the temperature at the lower part of the pile was $5^{\circ}C$ higher than that of conventional pile. This was more favorable for aerobic fermentation. Meanwhile, ash ratio of prototype ($30.9{\pm}1.1%$) was higher than that of control $28.4{\pm}1.6%$. In the case of prototype turner agitation, the yield of mushroom cultivation was $880kg/66m^2$, that was 22.9% higher than the conventional control yield of $716kg/66m^2$.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.493-498
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• 2019

In polymer exchange membrane fuel cells, it is crucial to fabricate a highly active and thin Pt catalyst layer for the smooth mass transport of dissolved oxygen and water. Although a highly loaded platinum (Pt) catalyst based on the hydrothermal synthesis has been reported in several studies, its growing behaviors and kinetics were yet to be understood. In this study, we investigated the growth of Pt crystal in suspension after the reduction step depending on a stirring time and evaluated the electrochemical activity. For only a couple of hours in the early stage, Pt colloids were adsorbed on the Pt-carbon catalyst and the Pt crystal was grown. After that, the small Pt colloid was formed by another nucleation step, which did not involve the growth of Pt crystal. We reveal that the Pt-Carbon catalyst with stirring for 6 h showed a high activity toward the oxygen reduction reaction.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.206.1-206.1
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• 2013

유기 혼합물을 사용한 비휘발성 메모리 소자는 간단히 공정 할 수 있고 생산성이 높기 때문에 많은 연구가 진행 중이다. 하지만 종류가 많은 유기 혼합물 중에서, [6,6]- phenyl-C85 butyric acid methyl ester (PCBM) 나노 입자가 고분자 박막에 분산되어 있는 유기 혼합물을 사용하여 제작한 메모리 소자에 대한 연구는 아직 미미하다. 본 연구에서는 PCBM 나노 입자를 포함한 polymethyl methacrylate (PMMA) 박막을 활성층으로 사용하는 비휘발성 메모리 소자를 제작하고 활성층의 두께를 변화하며 전기적 특성과 안정성에 대한 실험을 통해 성능을 평가했다. 소자는 PCBM 나노 입자와 PMMA를 클로로벤젠으로 용해시킨 후에 초음파 교반기를 사용하여 PCBM 나노 입자가 PMMA용액에 고르게 섞이도록 해서 제작하였다. Indium tin oxide (ITO)가 증착한 유리기판 위에 PCBM/PMMA 형성된 고분자 용액을 여러가지 rpm 속도로 스핀 코팅하였다. 용매를 가열해서 제거하여, PCBM 나노 입자가 PMMA에 분산된 두께가 다른 박막을 형성 하였다. 상부 전극은 분산된 PMMA 박막 위에 열 진공 증착기를 이용하여 제작하였다. 본 연구에서 전류-전압 (I-V) 측정을 사용하여 메모리 소자의 기억층의 두께 변화에 따른 전기적 성질을 관찰 하였다. I-V 측정 결과는 특정 두께의 박막에서 큰 ON/OFF 전류 비율을 보였다. 기억층의 두께가 최적화된 소자로 형성된 박막에서 전류-시간 유지 특성을 측정하여 소자의 ON/OFF 비율이 $1{\times}104$ 초까지 유지되는 것을 확인 할 수 있었다. 나노 입자가 포함된 박막의 특정 두께에서 성능이 향상된 메모리 특성을 보이는 것을 확인하였다.

• Journal of Power System Engineering
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• v.16 no.1
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• pp.30-37
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• 2012

공기 양수 펌프는 재생 에너지 분야, 부식 및 마모 특성의 유체의 활용 등 높은 신뢰성과 낮은 유지보수 비용을 필요로 하는 분야에서 그 사용이 증대되고 있다. 본 연구에서는 소형 공기 양수 펌프의 성능 평가 및 기초 데이터를 얻기 위한 연구로, D=0.012~0.019m, L=0.933m인 배관의 침수 깊이(${\beta}$=0.55,0.60,0.65,0.70)에 따른 수치해석을 수행하였다. 수치 해석 및 실험 결과는 유사성을 뛰었으며, 펌프의 사양과 효율은 공기의 질량 유속 비, 침수 깊이 비와 양수 배관의 길이에 관한 함수로 나타났다. 그리고 최대 물과 공기 질량 유속의 비는 각 배관에서 서로 다른 침수 깊이의 비로 나타났으며, 공기 양수 펌프의 최대 효율이 발생되는 운전조건은 슬러그(slug)와 슬러그 교반 정도(slug-churn flow regime)에 따라 나타남을 알 수 있었다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.148-150
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• 2015

최근 가압경수로 핵연료는 다양한 형태의 원자로의 개발 및 다양한 운전 방식을 요구한다. 장주기 운전이 가능한 고연소도 핵연료의 지속적인 성능 개선이 필요하다. 핵연료에서 가연성 중성자 흡수체(Burnable absorber-BA) 역할은 매우 중요하다. 다양한 원자로 및 다양한 운전방식을 대비하여 BA 제조에 유연성을 고려하면 핵연료 피복관 내부에 직접 코팅하는 것이 바람직하다. 이에 피복관 내부표면에 직접 금속도금이 가능 여부와 기존에 많이 사용하던 전해도금에서 발생되는 기포에 의한 불균질한 도금(핀홀) 문제점 해결 방안을 고안하였다. 본 연구에서는 초임계 이산화탄소와 전해도금액간의 초음파 교반을 통한 강한 진동에 의해 매크로 에멀젼을 형성시켜 피 도금 물질 표면에 얇은 막을 얻는 도금 방법을 적용하였다. 초임계 유체를 이용한 전해도금을 적용한 결과 균질한 얇은 도금 막을 증착 시켰으며, 기포에 의한 핀홀 현상을 억제하였다. 또한 전해도금액의 사용량을 최소화 하여 폐수 발생 문제를 개선하였다.

• Nuclear Engineering and Technology
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• v.27 no.4
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• pp.626-634
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• 1995

소수성 고운자촉매는 중수형 원자력발전소의 감속재 및 냉각재로 사용되는 중수의 제조, 그리고 발전소의 가동에 따라 중수중에 축적되는 삼중수소의 제거공정 둥에 이용된다. 여러 소수성 담체중 하나인 소수성 고분자담체를 제조하기 위하여 스티렌-디비닐벤젠의 제조 특성을 실험하였다. 제조된 담체에 백금 금속을 담지시켜 촉매를 완성한 후 삼중수소제거 실증실험을 통하여 촉매성능을 확인하였다. 스티렌-디비닐벤젠 고분자담체의 제조시 담체의 기공 특성 및 비표면적에 대한 용매의 영향을 실험하였다. 또한 용매비를 변화시킨 경우에는 solvating power 값을 계산하여 거시기공 형태의 담체 형성기준을 정하였고 여기에 따른 기공 특성 및 비표면적 변화를 부인하였다. 담체의 제조 후 후처리 방법을 변화시켜 기공 특성 및 비표면적 변화를 확인하였고, 이의 결과를 통하여 적절한 후처리 방법을 정하였다. 담체의 입자크기를 조절하기 위해 중합반응 과정중의 교반속도를 변화시켜 담체의 크기 변화를 실험하였다. 제조된 담체에 백금 금속을 담지시켜 촉매를 완성한 후 삼중수소제거 반응실험을 통해 촉매의 활성을 확인하였다.