• Advances in environmental research
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• 제6권3호
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• pp.159-171
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• 2017

A successful oil well drilling depends largely on a good mud Program. During drilling, mud provides sufficient hydrostatic pressure, removes drill cuttings and cools drill bits. Mud additives are always required to provide sufficient hydrostatic pressure to ensure borehole stability. Barium Sulphate ($BaSO_4$) also known as barite is the prevalent weighting material but there is needed to develop local materials to augment the use of Barite. The present search is concerned on the early Carboniferous succession exposed in Um Bogma Formation, west central Sinai, Egypt as a new weighting agent in drilling fluids. The increases in the cost of drilling fluids and a shortage of using barite have introduced the locale dolomite as alternative weighting materials. The rheological properties of mud drilling samples weighted by local dolomite samples are being examined and investigated to know its potential to be used as a weighting material in drilling mud. Two mud samples were prepared which comprised of fresh water, caustic soda, bentonite and the weighting material. The weighting materials are added to achieve the required density. The first sample: Water-based mud with commercial barite of density between 10.00 lb/gm and 18.00 lb/gm. The second sample: Water-based mud with dolomite of density between 10.00 lb/gm and 18.00 lb/gm. These samples were analyzed and the density, rheological properties, aging of barite and dolomite and solid contents were investigated. At 10.00 lb/gm, the yield point of dolomite was $20.00lb/100ft^2$ and barite $22.00lb/100ft^2$ while the 10 second gel strength of dolomite was $30.00lb/100ft^2$ and $22.00lb/100ft^2$ for barite. Similarly, little difference was observed in plastic and apparent viscosities. At 10.00 lb/gm, the plastic and apparent viscosities of dolomite were 8.00 cp and 20.00 cp while barite was 8.00 cp and 24.00 cp. The result show that dolomite mud sample gave a little higher yield point and gel strength than barite mud sample. Therefore, dolomite has the potential to be used as weighting material in drilling mud in place of barite thereby enhancing the local content initiative of the government. When dolomite is sourced locally and used it will reduce overall mud and drilling costs.

• 구강회복응용과학지
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• 제25권1호
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• pp.31-40
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• 2009

고무인상재의 유변학적 특성은 높은 정확성을 가진 인상체의 채득에 중요한 역할을 한다. 그러나 국산 고무인상재의 유변학적 특성에 관한 연구가 거의 이루어지지 않았다. 이 연구는 국산 및 수입 고무 인상재의 유변학적 특성을 측정, 연구함으로써 임상적 과정에서 정확성 높은 인상채득에 도움이 되고자 함이다. 시판중인 Type 3 점성을 가진 6종의 고무인상재의 유변학적 특징을 측정하였다. 2종의 국산 폴리비닐실록산, 3종의 수입 폴리비닐실록산, 1종의 폴리이써, 1종의 폴리썰파이드에 대하여 plate 대 plate 형의 rotational rheometer인 HAAKE RHEOSTRESS $1^{(R)}$ 이용하여 Mixing 후 900초간 G′, Loss tangent 값을 측정하였다. 각 제품 당 3회씩 측정 후 통계분석하였다. 국산 PVS, 수입 PVS, Polyether, Polysulfide 모두 G′의 S자형 증가와, Loss tangent 값의 S자형 감소를 보였다. 경화 후 G′ 값의 최대치는 Polyether였으며, 최소치는 Polysulfide였다. Loss tangent의 초기값은 폴리이써 인상재에서 가장 높았으며 국산 폴리비닐실록산 인상재에서 가장 낮았다. 같은 점조도를 가진 국산 PVS 와 수입 PVS의 G′ 값은 유의한 차이가 없었으나, 초기 Loss tangent 값에서 유의한 차이가 나타났다.

• Applied Biological Chemistry
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• 제48권3호
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• pp.273-279
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• 2005

To develop cosmetics using Jindalae flowers (Rhododendron mucronulatum), the surface tensions of extracts were measured and the properties and stability of cream with extracts were investigated. The surface tension of 0.1% ethanol extract was 30.42 mN/m and that of distilled water was 72.2 mN/m. The surface tension of cream with 0.1% ethanol extract was similar to that of sample cream and the measured pH were weakly alkalic. The surface tension of 1% ethanol extract was the lowest value of 24.98 mN/m, the measured pH of cream with 1% ethanol extract was weakly acidic and the particle size of cream was stable. According to an oscillatory test, linear viscoelastic region was extended by adding of 1% water extract and 1% ethanol extract to cream, indicating that the cream had greater enhanced resistance for preserving inner structure as compared to outside stress.　Besides, as a result of the diminished loss angle of ethanol extract cream, the elasticity of cream was increased more than that of sample cream and cream with 0.1% ethanol extract. In contrast, in the case of the increased loss angle of water extract cream, the viscosity of cream was increased. In conclusion, Rhododendron mucronulatum can be deliberated as a cosmetic material because 0.1% water and ethanol extracts showed efficacious physiological activities and cream with 1% extracts could extend linear viscoelastic region.

• Advances in concrete construction
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• 제9권6호
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• pp.547-556
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• 2020

This study aimed to develop reference materials (RMs) that are chemically stable and can simulate the flow characteristics of cement paste. To this end, the candidate components of RMs were selected considering the currently required properties of RMs. Limestone, slag, silica, and kaolin were selected as substitutes for cement, while glycerol and corn syrup were selected as matrix fluids. Moreover, distilled water was used for mixing. To select the combinations of materials that meet all the required properties of RMs, flow characteristics were first analyzed. The results revealed that silica and kaolin exhibited bilateral nonlinearity. When an analysis was conducted over time, slag exhibited chemical reactions, including strength development. Moreover, fungi were observed in all mixtures with corn syrup. On the other hand, the combination of limestone, glycerol, and water exhibited a performance that met all the required properties of RMs. Thus, limestone, glycerol, and water were selected as the components of the RMs. When the influence of each component of the RMs on flow characteristics was analyzed, it was found that limestone affects the yield value, while the ratio of water and glycerol affects the plastic viscosity. Based on this, it was possible to select the mixing ratios for the RMs that can simulate the flow characteristics of cement paste under each mixing ratio. This relationship was established as an equation, which was verified under various mixing ratios. Finally, when the flow characteristics were analyzed under various temperature conditions, cement paste and the RMs exhibited similar tendencies in terms of flow characteristics. This indicated that the combinations of the selected materials could be used as RMs that can simulate the flow characteristics of cement paste with constant quality under various mixing ratio conditions and construction environment conditions.

• 한국세라믹학회지
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• 제38권9호
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• pp.860-865
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• 2001

본 논문은 출발물로서 2mol% CdO가 치환된 $0.05Pb(Mn_{1/3}Sb_{2/3})O_3-0.95Pb(Zr_{0.52}Ti_{0.48})O_3$ 분말을 제조 후, 닥터 블레이드 방법으로 green sheet를 제조하기 위한 slurry의 최적 공정첨가제 조성에 관한 연구를 수행하였다. 또한, 제조된 green sheet에 대하여 소결 특성과 두께 변환에 따른 유전 및 압전 특성을 관찰하였다. 공정첨가제의 첨가에 따른 점도거동을 통하여 slurry를 최적화하였고, TGA 분석으로 소결조건을 정하였으며, sheet의 특성에 미세구조와 XRD 등으로 측정하였다. 최적의 slurry는 고형분량 30vol%에 대해 분산제 3.0wt%에서 가장 안정화되었고, 이후 바인더/가소제(0.75/0.25) 3.0wt% 첨가시 점도는 7.55Pa${\cdot}$s이었다. Green sheet의 유전 및 압전 특성들은 각각 900$^{\circ}$C, 950$^{\circ}$C, 1000$^{\circ}$C로 소결온도를 증가함에 따라 다소 증가하였지만, 두께에 따른 특성들은 큰 변화가 관찰되지 않음을 확인하였다.

• 동아시아식생활학회지
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• 제14권4호
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• pp.370-378
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• 2004

The purpose of this study was to investigate the effect of added nutriprotein and rice powder as a plasticizer on physicohemical property, texture property of Backsulgi. In the physicochemical property, the content of proximate composition of nutriprotein was measured as 6.1% of moisture, 3.6% of carbohydrate, 84.3% of crude protein, 0.6% of crude lipid, 5.4% of ash. The raw material of rice powder was measured as 9.6% of moisture, 83.7% of carbohydrate, 6.0% of crude protein, 0.4% of crude lipid, 0.3% of ash. Swelling power and pore ratio of the control were 78.53% and 72.42%, and tended to increase as the amounts of nutriprotein and plastic rice powder increased. Aging by Avrami eguation retarded in Backsulgi added 10% plastic rice powder than rice powder Backsulgi. All the samples added 2, 4, 6, and 8% nutriprotein at the temperatures of 20 were more effective than others on aging. In texture properties, cohesiveness and springiness were not significantly changed by adding nutriprotein and not significantly changed during the storage period in all samples. Hardness and gumminess decreased by adding 2∼8% nutriprotein and increased during the storage period in all samples. Springiness and gumminess decreased by adding 40% plastic rice powder and increased during the storage period in all sample. Cohesiveness and hardness decreased by the increase of plastic rice powder. The texture characteristics by rheometer showed that Backsulgi with nutriprotein and plastic rice powder exhibited lower in hardness than the control, indicating that nutriprotein and plastic rice powder were effective in retarding retrogradation, which is better when storage time became longer.

• 한국건축시공학회지
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• 제2권4호
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• pp.145-152
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• 2002

High fluid concrete unlike OPC concrete is made with various material, and the phase of fresh concrete is considerably different. In order to understand fluidity phase and mix properties of high fluid concrete, concrete is required to access as suspension structure which consists of aggregate and paste. The focus of this paper is to analyze the test results and quantify the effect of mix proportions of mortar and fineness modulus of sand on the properties of fresh mortar. The effect of water-binder ratio. sand-binder ration. contents of ggbs (by mass of total cementitious materials). and various contents of water reducing agent on the yield stress and plastic viscosity of the mix is studied. Based on the experimental results, the fellowing conclusions can be drawn: (1) The mixing time needed for high fluid mortar was approximately two times more than that of ordinary portland mortar. (2) The fluidity phase of mortar could be explained by yield stress of mix and the fluidity of mortar. (3) As the content of ggbs increased, yield stress of mortar was decreased and plastic viscosity of it was increased. (4) For the high fluid mortar, it was appeared that sand-binder ratio should be below 1.5.

• 한국구조물진단유지관리공학회 논문집
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• 제25권5호
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• pp.135-140
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• 2021

본 연구에서는 일반강도 범위 콘크리트의 단면에서 골재 형상의 특성을 추출하고 이를 인공신경망과 이미지 프로세싱 기술에 적용하여 콘크리트의 압축강도를 예측하였다. 이를 위하여 면적, 둘레, 길이 등과 같은 일반적인 골재 형상 특성과 함께 골재의 거리-각도 특징을 수치적으로 표현하고 물성치 예측에 활용하였다. 그 결과, 콘크리트 압축강도에 영향을 미치는 주요변수를 사용하지 않고 단면의 골재 형상 특성만을 사용하여 압축강도 예측이 가능하였으며, 인공신경망 알고리즘 구축을 통해 예측 강도와 실제 강도의 상대오차 4.43% 이내의 범위에서 콘크리트 압축강도를 예측할 수 있었다. 본 연구에서 도출된 결과를 기반으로 골재의 거리-각도 특징을 활용하여 콘크리트의 유동성, 휨·인장강도 등 다양한 특성을 예측도 가능할 것으로 판단된다.

• 한국철도학회논문집
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• 제18권6호
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• pp.543-551
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• 2015

급속경화궤도는 자갈궤도를 콘크리트궤도로 개량하는 공법으로서 야간 차단시간에 공사가 이루어지기 때문에 시공속도를 충분히 확보하는 것이 중요하다. 시공시간의 대부분은 자갈을 철거하고 재포설하는 과정에 소요되는데 도상자갈을 교체하지 않는 무교환방식이 적용 가능하다면, 시공시간 및 공사비를 대폭적으로 절감할 수 있다. 본 논문에서는 도상자갈 무교환방식의 급속경화궤도공법을 개발하기 위하여 침투성이 매우 높은 대체 충전재를 제시하고 재료의 공극조건을 고려하여 층별로 분리주입하는 시공방식을 도입하였다. 분리주입은 공극률이 높은 상부도상층과 공극률이 낮은 하부 혼입층에 최적화된 재료를 분리 주입하여 필요한 소요강도를 확보할 수 있다. 이를 달성하기 위하여 우선적으로 도상자갈의 크기, 분포도, 형상에 따른 공극률, 공극의 크기, 유효길이, 비틀림도, 침투성에 따른 충전재의 유동학적 해석을 통하여 최적의 충전재를 설계하고자 하였다. 하부 혼입층에 충전되는 1차 충전재료는 세립화 도상의 충전성과 부착력을 확보할 수 있는 폴리머계 재료를 도입하였으며, 상부 도상층에 충전되는 2차 충전재는 상온 반응성 마그네시아-포스페이트(MPC, Magnesium-Phosphate Ceramic)를 도입하였다. 선정재료 및 구조에 대한 역학시험 결과, 기존 급속경화궤도에 준하는 성능을 확인하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제26권4호
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• pp.73-80
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• 2022

이 연구는 3D 프린팅 복합재료에 대하여 굳지 않은 상태에서는 시간에 따른 경시변화와 레올로지 특성을 평가하였으며, 굳은 상태에서는 적층된 시험체와 몰드 시험체에 대하여 압축강도와 쪼갬 인장강도 특성을 평가하였다. 3D 프린팅용 복합재료는 압출 30분 후부터 급격한 물성변화가 시작되고 90분까지 재료의 점도가 유지되는 경향을 나타나지만, 이송성능과 적층성능의 품질을 확보하기 위해서는 배합 후 60분 이내의 시공이 효과적임을 확인하였다. 적층 시험체의 압축강도는 몰드 시험체 대비 전 재령에서 동등이상의 성능을 나타내었다. 적층 시험체의 응력-변형률 곡선에서 초기 기울기는 몰드 시험체와 유사하게 나타났지만, 최대 응력 이후의 하강 기울기는 몰드 시험체 대비 평균적으로 1.9배 높게 나타나 상대적으로 취성적인 거동을 하였다. 적층 패턴으로 수직으로 측정한 쪼갬인장강도는 몰드 시험체 대비 약 6% 낮게 나타났으며, 적층 패턴을 수평으로 측정할때는 몰드 시험체와 거의 동일한 쪼갬 인장강도를 나타내었다. 이는 적층 시험체의 패턴 방향에 따라 수직하중에 대한 계면간의 부착력이 영향을 받기 때문으로 판단된다.