• Journal of the Korea Institute of Building Construction
• /
• v.18 no.3
• /
• pp.235-242
• /
• 2018

The objective of the paper is to investigate the effect of mix designing factors on the workability and rheological parameters of self compacting concrete in order to facilitate the difficulties of quality control of high sensitivity of SCC. Mix proportions of SCC were prepared with various conditions of coarse, and fine aggregate, and unit water content, and the SCC mixtures were tested on workability, rheological properties to provide basic data for quantitative evaluation. Test results indicated that the yield stress of SCC decreased with increasing the coarse aggregate volume ratio, and increased with increasing the amount of VMA. However, unit water content, fine aggregate type, and air content didn't affect the yield stress value. The plastic viscosity according to the mixing factors showed a similar tendency to the yield stress. In addition, there was no correlation between yield stress and workability (flow, T50, V-lot). However, there was closely correlation among plastic viscosity and T50 and V-lot. Especially, T50 and V-lot time decreased with decreasing plastic viscosity.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 2001.04a
• /
• pp.88-88
• /
• 2001

최근 들어 초지기의 고속화, 원료의 저급화, 가공작업의 온라인화에 따라 초지기 상에서 안 정된 조업성이 더욱 중요하게 부각되고 있다. 이러한 초지 시스랩의 변화에 따라 사이징 효과의 발현 속도에 대한 관심이 고조되고 있다. 중성 사이징 시스템으로 ASA를 적용할 경우에는 초지기상에서 사이즈도의 대부분이 발현되기 때문에 온라인 후가공 작업의 안정성이 향상되며 사이즈프레스에서 조업성 역시 개선될 수 있을 것으로 기대된다. 본 연구에서는 가격이 저렴하고 국내 수급이 용이한 옥수수 양성전분을 ASA 유화안정제로 이용하기 위해서 OSA (Octenyl Succinic Anhydride)를 이용한 에스테르화 및 산가수분해를 통하 여 ASA 에멀션의 안정성 및 사이징 효과를 개선시킨 전분을 개발하고 그 효과를 규명하고자 하였 다. 이를 위해 전분을 FT-IR을 이용하여 분석하고 호액의 pH, 전기전도도, 전하밀도, 점도 변화 등 을 측정하였을 뿐 아니라 ASA 유화액의 pH, 전기전도도, 시간에 따른 가수분해 안정성 등을 평가 하였다. 또한 ASA 에멀션의 입도 변화 섬유에 대한 흡착특성과 수초지의 사이즈도를 평가하였다. 그 결과는 다음과 같았다. 첫째,OSA 전분의 사용에 따라 전분 호화액의 pH와 전기전도도의 변화는 나타나지 않았 다. 전하밀도는 첨가량이 증가할수록 감소하였으며 호화액의 점도는 상숭하였다. 또 OSA 전분의 적 용이 수초지의 사이즈도에는 영향을 주지 않았다. 그러나 OSA 전분을 사용하여 제조된 ASA 유화 액의 가수분해 안정성은 향상되었다. 이것은 콜로이드 상의 ASA 입자를 캡슐화 하는데 있어 소수성 을 띠고 있는 OSA 전분이 보다 강하고 안정하게 흡착하기 때문인 것으로 판단되었다. 둘째, 전분의 호화 시 H2S04을 사용하여 전분의 산 가수분해를 유도할 수 있었다. 이를 통 하여 전분 호화액의 pH는 낮아지고 전기전도도는 증가하였으나 전하밀도의 변화는 없었다. 또한 겔 화 온도가 낮아지고 저온에서의 점도가 상승하는 변화를 나타냈다. IN-H2S04를 2.3%까지 첨가하였 을 때 ASA 에멀션의 입도가 더욱 감소하였고 섬유에 대한 흡착량이 증가하였으며 수초지의 사이즈 도가 향상되었다. 특히 기존에 사용되어 오던 감자 양성전분에 비해 최대 90%까지 사이즈도의 향상 이 있었다.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.28 no.4
• /
• pp.397-400
• /
• 1995

Effects of rheological parameters, such as shear rate, temperature, concerntration, salts on the apparent viscosity of chitosan(deacetylation degree: $84\%$, Mw: 267,000) dissolved in acetate buffer(pH 4.5) were investigated. Rheologiral properties of chitosan solution from cuticle of red snow crab (Chinonecetes japonicus) are as follows. $0.5\%$ chitosan in 0.1M acetate buffer (pH 4.5) solution showed Bingham flow having hysteresis loop. It's flow equation was $\sigma=0.757+19.6_\gamma(r^2=0.99)$. The viscosity of chitosan solution is exponentially increased with its concentration, and showed Arrhenius dependence with respect to the temperature $(10^{\circ}C-40^{\circ}C).$ When various salts were added to chitosan solution, the viscosity decreased as the concentration of counterion increased. But the type ot counterions itself does not have any significant effects on the viscosity.

• Journal of the Korean Applied Science and Technology
• /
• v.31 no.4
• /
• pp.623-627
• /
• 2014

Emulsions are a class of disperse systems consisting of two immiscible liquids. Emulsions are affected by the size of oil drop, the type of continuous and disperse phase, the ratio of continuous and disperse phase, the type of emulsifies and emulsification devices. This study is to observe the viscosity of emulsions with oil polarities and interpret the results by organic conceptual diagram. The emulsions were made with hydrocarbon, ester and silicone oils and then the viscosity of emulsions was measured. As the oil polarity was increased, the viscosity of emulsion was decreased by reducing the amount of emulsifies and emulsion stabilizers arranged at interface. Organic conceptual diagram was used to compare the polarities among oils numerically. The interpretation of organic conceptual diagram and the results of experimental measurement were corresponded except emulsion made with silicone oil.

• Clean Technology
• /
• v.20 no.2
• /
• pp.97-102
• /
• 2014

Currently various studies are underway for dispensing high-viscosity phosphor. These studies have reported limitations and challenges in the dispensing process. The discharged amount of phosphor was approximately the same each time which is important for the implementation of high-efficiency white LED technology. This paper present high-viscosity phosphor dispensing process for white LED implementation by using electrostatic printing technology. The voltage controlled DOD (Drop-On-Demand) discharge experiment was studied to determine angle of drop meniscus at nozzle and dot diameter. With increase in Discharge voltage, the discharge angle of meniscus increased while dot diameter decreased. Therefore it can be concluded that we can control the discharge rate by controling the discharge angle of meniscus.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2009.10a
• /
• pp.141-141
• /
• 2009

EHD(electrohydrodynamic) 증착법을 적용하여 코팅층 표면복합구조제어를 연구하였다. 이 방법을 이용하여 표면구조 제어를 통한 친/소수 코팅층 개발의 제반 조건들을 탐색한다. 화학적으로 안정한 코팅층을 형성할 수 있는 전구체 물질을 용매에 혼합하고, 전구체 물질의 농도를 조절하여 다양한 점도의 용액을 합성하고, 전기장을 적절한 범위에서 변화시키면서 용액의 점도와 전기장의 변화에 따른 코팅층의 표면형상을 체계적으로 조사하고, 주요 공정 변수인 용액 전구체농도와 전기장에 따른 표면형상 변화에 대한 공정 MAP을 조사하여 초친수/초발수 특성을 나타내는 최적 표면구조를 예측한다.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.2 no.3
• /
• pp.70-79
• /
• 1998

The PEG and PCP have been used as a binder of high energy and minimum smoke propellant. In this study, PEG, PCP 0260, PCP 1270 and mixed PEG/PCP as a prepolymer were used, and also used BTTN/DEGDN and BTTN/TMETN as a plasticizer. Before being cured, the solution viscosity of prepolymer and plasticizer was measured with various contents of PCP in PEG and contents of plasticizer at $20^{\cire}C$~$60^{\cire}C$. The results were shown the increased concentration of PCP enhanced the viscosity of solution due to the hydrogen bond of PCP, and the increased contents of plasticizer undoubtedly decrease the viscosity of solution. The cured binders were tested for mechanical properties and measured for glass transition temperature with various concentration of PCP in PEG and contents of plasticizer. The increased concentration of PCP has shown better mechanical properties. This results were attributed to the H-bond. Also, the glass transition temperature was lowered with the higher contents of PCP Finally, with the higher content of PCP in PEG, the better mechanical properties and the lower glass transition temperature and the higher viscosity of solution were shown.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
• /
• 2002.04a
• /
• pp.80.1-80
• /
• 2002

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.41 no.11
• /
• pp.1596-1602
• /
• 2012

Eight rice cultivars grown in Korea were analyzed to investigate the quality of flour prepared using wet and dry grinding methods. The hardness of the kernel was related with starch damage following dry grinding but not following wet grinding. Although Chenmaai had the hardest steeped kernel, its flour exhibited minimal starch damage, a lower water absorption index (WAI), and a smaller difference between the RVA properties of wet and dry ground flour. However, Seolgan and Suweon517 are soft grains, and their flours had more starch damage and a higher WAI. In general, soft kernels produce better grinding characteristics. However, our wet grinding results indicated that grain hardness was not the main factor affecting the grinding characteristics. Even Chenmaai, with its hard kernels, had good grinding characteristics, whereas the softer kernels of Seolgan and Suweon517 did not show the appropriate grinding characteristics.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2002.05b
• /
• pp.135-136
• /
• 2002

수지 및 실란트의 제조 과정에서 불양의 원인이 되는 수분을 흡습하기 위하기 위하여 첨가하는 ？ CaO는 분진 공해가 발생하며 제품의 불량의 원인이 된다. 이러한 단점을 개선하기 위하여 CaO의 함량이 80% 이상인 에멀젼의 제조할 때 용매는 DOP, 분산제는 습윤성과 분산성이 우수한 카프복실산 에스테르 종류의 계면활성제를 사용하였고, 이어서 분자량이 큰 응집 방지제를 첨가하여 습기 제거제 에멀젼을 완성하였다. 이후에 온도에 따라서 변화하는 점도를 일정하게 유지하기 위하여 POENPE를 첨가하므로서 계절에 상관없이 사용이 가능하도록 하였다.