• Applied Chemistry for Engineering
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• v.30 no.5
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• pp.597-605
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• 2019

In order to improve the adhesion of water-based adhesive, gemini type nonionic reactive surfactants were synthesized and applied to water-based adhesives. The surfactants were synthesized by using maleic acid and polyoxyethylene cetyl ether having different length of ethylene oxide and confirmed by FT-IR and $^1H-NMR$. Their appearance was light yellow wax. The cloud point of the compound was more than $78^{\circ}C$. The measured critical micelle concentration (c.m.c) was $1.0{\times}10^{-4}{\sim}7.0{\times}10^{-4}mol/L$ and surface tension at c.m.c was 25.9~32.0 mN/m. As the number of ethylene oxide increased, the emulsifying power was improved. The foaming height of each compound by Ross-Miles method was 1.4~4.5 cm. The synthesized surfactants was then used as an emulsifier in emulsion polymerization of water-based adhesives and its physical properties were evaluated. The solid contents of prepared adhesives was 59%. The average particle size and initial tackiness of the prepared adhesives were 164~297 nm and ball no. of 20~32, respectively. The peel strength was $1.8{\sim}2.1kg_f/mm$. The retention rate of adhesives viscosity was evaluated to 99% during 30 days. Therefore, synthesized gemini type nonionic reactive surfactants are expected to be applied as an emulsifier for the high adhesive force.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.6
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• pp.665-674
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• 2015

A TSL (Thin Spray-on Liner) which consists of polymers has a higher initial strength, faster construction time and higher waterproofing performance than the conventional cementitious shotcrete. Main supporting mechanism of TSL is the adhesion and tensile strength which is distinct from the conventional shotcrete. Even though highly in demand due to its outstanding characteristics, TSL is not yet well-known support material. In this study, to evaluate contact behavior of TSL, numerical analysis was performed with comparing result from laboratory tests. From the analysis, cohesive behavior at the contact surface between TSL and rock can be evaluated by using combination of cohesive and the damage model. In addition, results show that the cohesive stiffness controled slope between force and displacement, the fracture energy controled level of force at the contact.

• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.211-220
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• 2012

The numerical modeling and simulation have been used increasingly as tools for examining and interpreting the bulk structure and properties of materials. The use of molecular dynamics (MD) simulations to model the structure of materials is now both widespread and reasonably well understood. In this research, we introduced the numerical method to calculate the physico-chemical properties such as a diffusion coefficient and a viscosity of clay mineral. In this research, a series of MD calculations were performed for clay mineral and clay-water systems, appropriate to a saturated deep geological setting. Then, by using homogenization analysis (HA), the diffusion coefficients are calculated for conditions of the spatial distribution of the water viscosity associated with some configuration of clay minerals. This result of numerical analysis is quite similar to the previous experimental results. It means that the introduced numerical method is very useful to calculate the physico-chemical properties of clay minerals under various environmental conditions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.947-954
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• 2014

In general, Fracture of the material is not occurring of the maximum normal stress or the maximum shear stress failure in the state. Maximum normal stress and maximum shear stress in the state of Critical coupling from being destroyed based on the Mohr-Coulomb theory. Couple of different mixtures, including permeable asphalt pavement, SMA and dense-graded asphalt mixture, were used for compression triaxial test at $45^{\circ}C$ and $60^{\circ}C$. Mohr-Coulomb theory to the analysis of compression triaxial test result of the internal friction angle $38.9^{\circ}{\sim}46.9^{\circ}$ measured somewhat irregularly, but in the case of cohesion, depending on whether the temperature and immersion of the specimen appeared differently. In addition, Indirect tensile test and compression triaxial test of the asphalt mixture to determine the correlation between compression triaxial test results assessed as cohesion and internal friction angle calculated using the theoretical Indirect tensile strength and measured indirectly tensile strength were analyzed. The Measured & Predicted IDT St values tended to be proportional.

• Journal of the Korean GEO-environmental Society
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• v.11 no.3
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• pp.23-32
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• 2010

In this study, Generally sandbag was used to reinforce slope or restore levee by using the in-situ material. To increase shear strength of sandbag, the Velcro system was effective for geosynthetic interface and make up for the weakness of shear strength between sandbag to sandbag. In this study, shear properties of geosynthetic-geosynthetic and geosynthetic-soil were evaluated from large scale direct shear tests. The cohesion and the angle of internal friction of each interface was evaluated. And laboratory model tests were performed to compare strength of reinforcement with strength of none reinforcement. As a result of this study, the cohesion and the angle of internal friction of each interface was increased, especially the cohesion was increased more than the angle of internal friction. Also according to the result of model test, the bearing capacity was increased by 20%.

• Journal of the Korean Geotechnical Society
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• v.37 no.7
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• pp.5-12
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• 2021

When drilling investigations for Rock Slopes are not possible, it is often difficult to calculate the Ground Design Constants required for the Limit Equilibrium Analysis. Therefore, the outcrops or partially cutted Rock Slopes were analysed using JRC and JCS that can be easily and conveniently measured. In particular, the effect of the JRC on the Safety Factor or the Rock Slopes was analyzed intensively, and the results were presented as a relationship formula and Table. When the Rock slope was stable, the JRC increased by an average of 9.0% as the slope height increased, and increased by an average of 29.8% as the slope angle increased. JRC was more sensitive to slope angle changes. The Cohesion corresponding to JRC was calculated from JRC-Fs formula. JRC and Cohesion showed a nonlinear relationship, and the Cohesion was about 8.0% more sensitive to slope height changes than slope angle changes.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.7
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• pp.801-809
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• 2007

Fly ash and blast furnace slag are an industrial by-product that can be alkali-activated to yield adhesive and cementitious materials, whose production is less energy-intensive and emits less $CO_2$ than ordinary Portland cement manufacture. A laboratory investigation was carried out to evaluate the effect of alkali-activating conditions on compressive strength of fly ash/slag cement and the acid corrosion resistance of this cement. Two alkali activator solution, NaOH and waterglass + NaOH solutions, were used. Waterglass concentration was the factor that gave the highest compressive strength in all tests. The next significant factor was the NaOH concentration, followed by curing temperature. Acid corrosion resistance of FC(fly ash cement) and FSC(fly ash/slag cement), such as sulfuric$(H_2SO_4)$ and hydrochloric acid(HCl), was for better than Portland cement(PC).

• Korean Journal of Food Science and Technology
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• v.42 no.4
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• pp.459-467
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• 2010

The substitution effects of broccoli powder for flour in the preparation of sponge cake were determined by physicochemical and sensory analysis. The specific gravity and viscosity of the cake batter and cooking loss of the cake increased with an increasing amount of broccoli powder, whereas specific loaf volume and moisture content of the cake decreased. Lightness, redness, and yellowness of crust and crumb decreased with increasing broccoli powder content. A texture analyses revealed that the hardness, chewiness, gumminess, adhesiveness, and fracturability of the cake tended to increase in proportion to the amount of broccoli powder in the formula. In the sensory evaluation, cake prepared with 5% broccoli powder was similar to the control in moistness, softness, chewiness, and springiness. These results suggest that adding 5% broccoli powder is the best substitution ratio for sponge cake.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.158.1-158
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• 2003

손바닥 선인장 (Opuntia ficus-indica)은 백년초라고도 불리어지는 다년생 식물로 멕시코가 그 원산지이며, 우리나라에는 약 200년 전에 들어와 제주도 월령마을과 마라도 남쪽해변 산지에 자연상태로 착생되어 제주도 지방 기념물 제 35호로 지정되어 있다. 현재는 북제주군의 월평리를 중심으로 노지에서 재배되고 있으며, 열매는 서양배 모양을 하고 점질물과 함께 다량의 적색계 색소를 함유하고 있다. 열매는 공복에 갈아 마시면 변비치료, 이뇨효과, 장운동 활성화 및 식욕증진에 효과가 있으며, 당뇨, 고혈압, 천식에도 효능이 있다고 하여 민간요법으로 사용되어 왔다. 또한 라디칼 소거, tyrosinase 활성 억제, 항알레르기 활성, 항산화 및 항균활성, 스트레스 항위궤양 효과 등 다양한 기능성이 보고되고 있다. 색소성분은 함질소 anthocyanin의 일종인 betalaines로 적색의 betacyanines과 황색의 betaxanthines 로 구성되어 있으며 75~95%가 betacyanines에 속하는 것으로 알려져 있다. 지금까지 손바닥 선인장에 관한 연구로는 색소의 안정성, 품종별 아미노산 조성, 성분 특성, 추출물을 첨가한 면류의 품질 특성 등으로 상당히 단편적인 연구에 그치고 있다. 본 연구는 최근 식생활의 서구화로 쌀 위주의 식생활에 많은 변화를 가져와 쌀 소비량은 해마다 줄어들고 있는 반면 기능성을 가미한 쌀의 소비가 늘고 있음을 감안하여, 손바닥 선인장 물추출물로 코팅한 유색미의 취반특성을 조사하였다. 그 결과 유색미는 자청색을 띠었으나 그 취반은 연한 황색을 띠었다. 손바닥 선장의 유리아미노산은 $\alpha$-aminoadipic acid가 83.22 mg%, tyrosine이 75.61 mg%로 주 아미노산을 이루었다. 유색미 취반에는 백미 취반에는 검출되지 않는 $\alpha$-aminoadipic acid가 1.66 mg% 함유되었으며, 백미 취반에 비하여 arginine과 leucine은 2배, histidine과 Iysine은 각각 2.3배 및 4.2배, tyrosine은 3.4배가 함유되었다. 손바닥 선인장의 주요 무기질은 Ca, K및 Mg으로 전체 무기질 함량의 약 95%를 차지하였으며 이들 무기질의 함량은 유색미 취반이 백미취반에 비하여 10~45%가 높았다. 밥알의 견고성, 점착성 및 깨짐성은 유색미 취반에서 낮았으나 응집성은 높았다. 단맛은 유색미 취반과 백미 취반 간의 뚜렷한 차이가 없었으나 구수한 맛과 쫄깃한 맛은 유색미 취반에서 높았다. 취반의 종합적인 기호도 및 색상에 대한 기호도는 유의적인 차이가 없었다.

• Proceedings of the KSEG Conference
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• 2005.04a
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• pp.235-242
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• 2005

본 연구에서는 퇴적암의 시험 관련자료 2,000 여건을 사암(역암 포함), 셰일 및 석회암으로 구분하여 흡수율, 단위중량, 일축압축강도, 점착력, 내부마찰각, 인장강도, 탄성계수, P파속도 및 S파속도 등의 특성치 분포도와 상관성을 분석하였다. 이러한 암석 특성치는 지하공간개발시 안전하고 경제적인 설계와 시공에 참고자료로 활용될 수 있는데 퇴적암의 강도특성 분석결과 사암과 석회암이 셰일 보다 전반적으로 양호하여 대규모 지하공간개발에 유리한 것으로 평가하였으며, 또 84% 신뢰도를 만족하는 범위에서 퇴적암의 암종별 공학적 특성치의 상관관계식을 유도하였다.