• Resources Recycling
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• v.10 no.1
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• pp.16-24
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• 2001

In this study, various mechanical properties of concretes employing waste concrete as aggregate were examined. These concretes were obtained by mixing seven types of aggregate for different ratios. So, the experimental variables are the kinds of aggregates (some different aggregate compositions) and W/C ratio (0.40, 0.45, 0.50). From experimental results, the reliable regression analysis equations between compressive strength and various experimental data for recycled aggregate concrete are presented. Consequently, this study was accomplished to investigate basic engineering properties of recycled aggregate concrete using waste concrete.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2007.05a
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• pp.64-66
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• 2007

범주화(categorization)은 제품디자인에 있어서 매우 중요하다. 범주화의 유형에 따라 소비자의 감성이 다르고 감성의 차이에 따라 디자인 컨셉 및 디자인요소가 다르게 배합되어야 하기 때문이다. 특히 요즘처럼 제품라인이 확대되어 제품의 차별화가 모호한 경우에는 범주화과정이 필요하다. 즉 감성의 유사성정도를 바탕으로 정확한 범주를 정하고 컨셉화하여 소비자 지향적인 디자인을 제공해야 하는 것이다. 본 연구는 특정의 제품범주(장) 안에 유사한 하위 범주(고추장, 된장, 청국장, 쌈장, 간장)를 구성하고 있는 장류제품전체와 고추장, 된장, 청국장, 쌈장, 간장제품에 대한 소비자의 감성을 추출하고 그 유사성정도를 바탕으로 고추장, 된장, 청국장, 쌈장, 간장의 범주를 결정하여 디자인방향을 어떻게 결정해야 할지를 제시하는데 목적이 있다. 장류제품을 연구대상으로 한 것은 장류제품이 한국인의 식탁에서는 가장 기본적이고 중요한 제품 중의 하나이고 또 현대화시대의 라이프스타일과 환경의 변화로 시장이 확대되고 있기 때문이다. 실증연구는 전북지역과 서울지역의 소비자을 바탕으로 이루어졌다. 본 연구는 학문적 측면과 실무적 측면에서 제품디자인에 대한 다양한 통찰력을 제공할 것이다.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.292-295
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• 2011

본 논문에서는 배수성(저소음)포장을 포함하는 2-Layer 아스팔트 포장의 상부층과 하부층의 역학적인 특성을 평가하는데 목적이 있다. 연구 방법으로는 슈퍼페이브 배합설계로 2-Layer 아스팔트 포장의 상 하부층 시편을 제작하였으며, 시편 상부층의 최대공칭치수는 4.75mm이고 하부층의 최대공칭치수는 13mm이다. 이 시편에 대한 기본 물성 시험 실시 후 마샬 안정도 시험에 대한 안정도와 흐름값을 평가하였다. 그리고 상부층과 하부층의 자유단 공진주 시험을 통해 탄성계수(E)를 측정하였고, 비파괴 시험법인 슈미트해머(Schmidt hammer)를 이용해 반발경도를 측정한 후 강도를 추정하였다. 또한 일축압축시험으로 측정된 압축강도로 탄성계수($E_{50}$)를 계산하였다. 마지막으로 각각의 역학적 시험을 통해 얻어진 결과값으로 강도(qu)와 탄성계수 ($E_{50}$)의 상관관계와 추정식으로 구한 강도와 일축압축강도 시험으로 얻어진 강도와의 상관관계를 분석하였고, 자유단 공진주 시험의 탄성계수(E)값과 일축압축시험의 결과로 얻어진 탄성계수($E_{50}$)의 상관관계를 분석하였다.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.474-482
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• 2002

The purpose of the study is to establish an optimum geometry and optimum geometry factor through bond test of a structural synthetic fiber, which fully utilizes matrix anchoring without fiber fracturing with the maximum pullout resistance. Seven deformed structural synthetic fibers with widely different geometries were investigated and pullout test was conducted. Included parameters are seven different types of fiber and two of mortar matrixes. The test result shows that the crimped type structural synthetic fiber is significant improvement in the interface toughness(pullout energy) and pullout load. The pullout test was performed with various size of crimped type structural synthetic fiber in order to invest optimum geometry factor, In the basis of the test results, optimum geometry factor is established such as D=b$^{{\alpha}0{\alpha}}$h$^{λ{\beta}}$.

• Elastomers and Composites
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• v.36 no.2
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• pp.79-85
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• 2001

It goes to be serious with environmental pollution cause waste rubber. That is why there are lot of studies for efficient recycle. The purpose of this study is to improve the physical properties of EPDM powder by using De-link system. We changed on the size of waste rubber powder and De-link contents. we examined the physical, rheological, mechanical properties. And also examined cross-link state at various De-link. Also we carried out morphological studies after making the weather strip's feature by optical microscope.

• Magazine of the Korea Concrete Institute
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• v.10 no.4
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• pp.171-182
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• 1998

Vibration-controlled concrete has been developed by using various concrete mixtures, such as latex, rubber powders, plastic resins and polystyrene(styrofoam). As part of the recycling research of obsolete aged tires and plastic materials, various vibration-reducing mixtures are used for 10 concrete panels having above 200 kg/cm$^2$ in uniaxial compressive strength. Plywood box with sand uniformly saturated by the raining device has been used for the analysis of the impact wave, of which data have been transfered by the FFT technique to comparatively investigate damping ratios of 10 concrete panels.According to wave propagation analysis on vibration-controlled concrete for this research, it can be concluded that Latex concrete has relatively larger damping ratios than those for noncontrolled normal concrete in a similar compressive strength

• Journal of the Korea Concrete Institute
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• v.18 no.1 s.91
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• pp.21-28
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• 2006

This paper presents both experimental and analytical studies for the development of an ECC(Engineered Cementitious Composites) using ground granulated blast furnace slag(slag). This material has been focused on achieving moderately high composite strength while maintaining high ductility, represented by strain-hardening behavior in uniaxial tension. In the material development, micromechanics was adopted to properly select optimized range of the composition based on steady-state cracking theory and experimental studies on matrix, and interfacial properties. A single fiber pullout test and a wedge splitting test were employed to measure the bond properties of the fiber in a matrix and the fracture toughness of mortar matrix. The addition of the slag resulted in slight increases in the frictional bond strength and the fracture toughness. Subsequent direct tensile tests demonstrate that the fiber reinforced mortar exhibited high ductile uniaxial tension behavior with a maximum strain capacity of 3.6%. Both ductility and tensile strength(~5.3 MPa) of the composite produced with slag were measured to be significantly higher than those of the composite without slag. The slag particles contribute to improving matrix strength and fiber dispersion, which is incorporated with enhanced workability attributed to the oxidized grain surface. This result suggests that, within the limited slag dosage employed in the present study, the contribution of slag particles to the workability overwhelms the side-effect of decreased potential of saturated multiple cracking.

• Journal of Animal Science and Technology
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• v.53 no.5
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• pp.441-450
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• 2011

This study was conducted to determine the effects of partial replacement of corn grain and soybean meal with agricultural by-product feeds on in vitro rumen fermentation characteristics and optimum levels of mixing ratio. The agricultural by-products to examine the effectiveness of the partial replacement of concentrate were wheat bran, corn gluten feed, bakery waste, soybean curd, rice bran, green kernel rice, soybean hull, distillers' grain, and mushroom substrate. In the first experiment, in vitro ruminal fermentation characteristics of feedstuffs were evaluated at 0, 3, 6, 12, 24, and 48 hours after incubation. In the second experiment, fermentation characteristics were investigated with green kernel rice and soybean curd which replaced corn grain or soybean meal. Feed were formulated with 40% corn grain + 20% soybean meal (T1), 40% corn grain + 17.5% soybean meal + 2.5% soybean curd (T2), 25% corn grain + 20% soybean meal + 15% green kernel rice (T3), and 30% corn grain + 15% soybean meal + 6% green kernel rice + 9% soybean curd (T4), respectively, with forage source of 10% alfalfa hay, 20% timothy hay, and 10% corn silage as fed-basis. In 24 and 48 hour cultivations, T4 showed significantly lower pH compared to T1, whereas in 3 and 24 hour cultivations, T4 showed significantly higher DM degradation compared to T1. In addition, the gas production of T3 was also higher than T1 (p<0.05). Overall results of the present experiments indicated that green kernel rice and soybean curd as agricultural by-products have the possibility of partial replacements of corn grain and soybean meal.

• Journal of the Korea Concrete Institute
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• v.21 no.2
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• pp.179-186
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• 2009

The peculiarity pointed out for high strength concrete is the occurrence of spalling during a fire. Recently, there are many efforts such as development of all types of spalling reducing materials and other innovative materials in various fields. Need is now to examine the adequate mixing proportions of these materials. This study intended to derive experimentally and statistically mix proportions that can represent the basic quality requirements as well as the optimal effects on the fire-resistance for 4 types of functional materials that are metakaolin, waste tire chip, polypropylene fiber and steel fiber. Here, the tests were planned through an optimal test method using an orthogonal array table with 4 parameters and 3 levels. The statistical analysis adopted the response surface analysis method. Results verified mutual complementary contribution between the materials when using a combination of the functional materials selected as parameters for the strengthening of the fire-resistance of 80 MPa-class high strength concrete. Besides, the optimal conditions of the fire-resistance strengthening materials derived through response surface analysis were a volumetric replacement of silica fume by 80% of metakaolin, a volumetric replacement of fine aggregates by 3% of tire waste chip, and an addition of 0.2% of the whole volume by polypropylene fiber without mixing of steel fiber. In such cases, the basic characteristics as well as the fire-resistant characteristics of high strength concrete were also satisfied.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.10-19
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• 2013

Recently, researches related to precast modular construction have been actively conducted for nuclear power plant, LNG gas tank, and small-medium PCCV as well as bridges and buildings. In this study, the precast panel cast with steel mesh reinforced mortar (SRM) which is similar reinforced ferrocement was developed for efficient precast construction, construction time reduction, and easy transportation. Mortar mixture with high strength and flowability was obtained from various case studies using silica fume and GGBS. Also, $1,200{\times}600{\times}150mm$ SRM and reinforced concrete (RC) panels were manufactured with reinforcing ratio of 2% and 4%. To verify structural performance of the SRM specimen, the basic material tests, free shrinkage test, and 3-point flexural test with a line loading were carried out. From the test results, it was determined that SRM specimens showed outstanding flexural capacity and ductility. However, the 4% reinforced SRM specimens must consider shear reinforcing to be used as a precast modular member.