• Journal of Energy Engineering
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• v.4 no.3
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• pp.372-378
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• 1995

분류층 석탄가스 반응온도에서 slag의 배출 조건을 원활하게 유지하기 위하여 CaCO3를 flux로 사용한 용융특성을 파악하였다. 첨가에 의한 용융온도는 flux 주입량에 따라 감소하다가 증가하였다. 최저 용융온도의 범위는 ash중 CaO 농도기준 30-40%의 범위에서 나타났으며, Base/Acid ratio에 따라 최소 용융온도는 ash중 무기물간의 eutetic effect가 작용함을 알 수 있었다. 고온에서의 slag 조성은 ash의 조성과 비교시 알카리 산화물의 휘발화와 SO2의 감소를 보여주고 있으며, salg중 환원성 가스가 증가함에 따라 금속 산화물의 환원에 의해 SiO2 조성은 증가하였다. CaCO3를 혼합한 시료를 질소분위기하에서 조제하여 점도를 측정한 결과, low silica ash의 경우 낮은 점도치를 보여주나, 250 poise 이하의 범위에서 고화되는 현상이 발생하였다. high silica ash에서는 CaCO3 투입에 의해 slag 점도는 감소하였는데, slag 분석 결과 CaO가 산소 제공물질(oxide doner)로 작용하여 silicate의 응집현상을 억제하는 것으로 나타났다.

• Proceedings of the Materials Research Society of Korea Conference
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• 1995.11a
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• pp.87-87
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• 1995

• Proceedings of the Korean Vacuum Society Conference
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• 2002.02a
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• pp.125-125
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• 2002

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1996.04a
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• pp.32-32
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• 1996

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.11a
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• pp.38-38
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• 1998

• Journal of the Korea Computer Graphics Society
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• v.23 no.1
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• pp.9-16
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• 2017

Simulating the clumping and stiffness of wet hair or fur is a challenging problem. The dynamics of wet hair or fur is characterized by the clumping and stiffness at the tip, which is easily seen in running animals or headbanging scenes. Existing methods address these phenomenon within pre-set scenarios. But there is no consensus on the method of depicting the details of wet hair. Hence, the present paper proposes a new method of modeling the clumping and stiffness of wet hair or fur. Previous studies focused on modeling the absorption of water into hair or fur, whereas this paper highlights a realistic simulation of wet hair. Unlike dry hair strands, wet hair strands adjacent to one another are subjected to the clumping force and gather together, while at the same time becoming stiff as the saturation of water increases. The proposed method builds on the surface tension model based on SPH (smoothed particle hydrodynamics) to simulate the clumping force and to adjust the hair elasticity by giving stiffness constraints. The present method enables a realistic simulation of wet hair by maintaining the clumping force of the wet hair even in dynamic motions, and by simulating the stiffness of hair in line with water saturation.

• Journal of Korea Game Society
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• v.11 no.1
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• pp.131-138
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• 2011

Recently in terrain rendeing, most researches introduce mipmap-based out-of-core methods for handling large sized DEM data which does not fit in main memory of general computer. However, mipmap-based LOD(level-of-detail) methods occur geometric errors which appear in data simplifying the higher LOD level. These geometric errors cause geometric popping effects where LOD level changes when viewpoint moves. In this paper, we propose vertex cohesion map for reducing geometric error. In preprocessing step, we generate vertex cohesion map, which is a texture that stores the vectors. By these vectors, each vertex will be cohered into the position in which the difference of gradient value is bigger than others. Therefore in terrain rendering, using vertex cohesion map can dramatically reduce the geometry popping effects rather than using mipmap.

• Composites Research
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• v.32 no.3
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• pp.134-140
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• 2019

Graphene nanoplatelets (GNP), one of the graphene derivatives is famous as the most proper candidate for industrial applications. However, current performance of GNPs as reinforcing filler in composites is limited by their agglomeration and physicochemical heterogeneity. Herein, an approach to produce non-covalently functionalized GNPs (F-GNPs) is reported which possesses potential to be extended as the industrial level of mass production. The one-step functionalization process uses melamine, a low-cost chemical, to prevent agglomeration and dispersion in polar solvents. Furthermore, a purification strategy called salting-out process based on differences in the dispersibility of the individual F-GNP flakes is reported to separate F-GNPs. The functionalization and separation process developed in this paper provides a strategy to use GNPs at the industrial level in composite applications.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.2
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• pp.101-109
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• 2004

In this study, the solid-liquid separation characteristics of swine wastewater were investigated for the coagulation and dissolved air flotation (DAF). Coagulation characteristics were studied using jar-tester with the different coagulants and dosage amounts. DAF characteristics were also investigated in terms of the different flotation conditions with the raw swine wastewater, pH adjustment only, and adding coagulants. When the raw swine wastewater was coagulated with the only inorganic coagulants, the proper inorganic coagulants were founded as $FeCl_3$ > PAC > Alum orderly, and the optimal coagulant dosages were founded as $1,000mg/{\ell}$, $1,500mg/{\ell}$, $1,500mg/{\ell}$, respectively. As the raw swine wastewater was treated with the polymer coagulants, the only cationic polymer coagulant showed an effective coagulation and the optimal dosage of cationic coagulant was founded as $200mg/{\ell}$. When the different dosages of cationic polymer was added to each $500mg/{\ell}$ of the inorganic coagulants, the proper inorganic coagulants were founded as $FeCl_3$ > Alum > PAC orderly, and optimal cationic polymer dosages was founded as $25mg/{\ell}$, $25mg/{\ell}$, and $100mg/{\ell}$, respectively. Resulting from the raw swine wastewater experiments using DAF without coagulation, the proper operation conditions of DAF were set to 400% of recycling ratio, 4 atm in air dissolving tank, and under pH 3. But the raw swine wastewater was difficult to successfully operate DAF without pre-coagulation. While the DAF separation after pre-coagulation using inorganic coagulants was not accomplished due to the low intensity of the floc, DAF after pre-coagulation using both the inorganic and cationic polymer coagulants was accomplished very well. Optimal dosage of cationic polymer coagulant in case of $500mg/{\ell}$ Alum dosage was founded as $500mg/{\ell}$.

• The Journal of Engineering Geology
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• v.28 no.1
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• pp.61-67
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• 2018

Grouting is reinforcement or cutoff method which uses the hardening agent which is typically represented by portland cement and injected into the ground or the structure. When mixing the cement in powder form with water, the particles tend to cohere each other. Once they cohered, the particle size tends to become larger while injection efficiency becomes lower. This study, in a bid to reduce the cohesion of cement, the screen was set inside the grout mixer so that the cement particles are separated while vibrating them. To validate the effect of vibration screen, comparison test was conducted by using ordinary portland cement, slag cement and micro cement. Viscosity test, bleeding test and grain-size analysis indicated that the characteristics varied significantly after passing through the vibration filter. It is expected that the vibration filter installed inside the grout mixer will reduce the cement cohesion when mixing with water.