• Composites Research
• /
• 제23권3호
• /
• pp.64-68
• /
• 2010

EPS 폼은 충격하중으로부터 전자제품의 파손을 방지하기 위하여 포장재로 많이 사용되는 경량소재이며 밀도, 미세구조, 변형률 속도에 따라 에너지 흡수성능이 달라진다. 본 연구에서는 변형률속도와 밀도의 변화에 대한 EPS 폼의 에너지 흡수성능을 평가하기 위하여 18.5 ~ 37.0kg/m3의 밀도를 갖는 EPS 폼의 압축시험을 수행하였다. 중고속 압축시험을 위하여 낙하방식의 시험기를 개발, 사용하였으며 변형률 속도 0.06/s ~ 60/s에서의 압축시험을 통하여 EPS 폼의 변형률속도 효과를 분석하였다. 시험 결과 변형률 속도가 0.06/s에서 60/s로 증가할 경우 EPS 폼의 강도는 약 1.7배 증가하는 것으로 관찰되었다. 또한 변형률 속도에 따른 소재의 민감도는 변형률이 증가할수록 커지는 것으로 관찰되었다.

• Journal of Korean Academy of Oral Health
• /
• 제43권3호
• /
• pp.118-123
• /
• 2019

Objectives: The purpose of this study was to investigate changes in the composition of artificial cariogenic biofilms using a Streptococcus mutans biofilm model over a period of time. Methods: We analyzed the dry weight, colony forming unit (CFU) number, extracellular polysaccharide (EPS) biovolume, and acid production rate of S. mutans biofilms formed on saliva-coated hydroxyapatite discs after 26 h, 50 h, 74 h, 98 h, 171 h, and 195 h. In addition, we performed a laser scanning confocal fluorescence microscopy to determine the bacterial volume, EPS biovolume, and biofilm thickness. We calculated the biofilm density using dry weight and EPS biovolume. Results: Over a period of time, there was no change in the CFU number and acid production rate of S. mutans biofilms, but there was an increase in the dry weight and EPS biovolume of S. mutans biofilms. The bacterial volume, EPS biovolume, and biofilm thickness only increased in the 50-h-old biofilm; however, no change was observed in 50-195-h-old biofilms. In addition, an increase in the biofilm density was observed over time. Conclusions: These results suggest that the acid production ability of cariogenic biofilms does not change, but the biofilm density increases over time. However, due to scientific information, further research needs to be conducted in the field of dentistry to get further insights on the progression of cariogenic biofilms over time.

• 한국농공학회지
• /
• 제41권1호
• /
• pp.79-85
• /
• 1999

Use of soils with crushed expanded polystyrene(EPS) satisfied both recycling of industrial waste and development of new light-weight fill materials. Objectives of the study were to make the mixed the mixed soils with the crushed EPS and to suggest the most rational mixing ration as a fill material. A series of laboratory tests was performed to investigate the relationship between miximum dry density and optimum moisture contenr and to find the variation of CBR for mixtures with 3 soils and 2 sizes of the crushed EPS. Results of the test showed that the sizes fo the curshed EPS had a little effect on the properties of mixed soils. But gradatiion of soils and mixing ration with the crushed EPS were important factors to characterize compaction properties of the mixed soils.

• Geomechanics and Engineering
• /
• 제14권6호
• /
• pp.533-544
• /
• 2018

The importance of using materials cost effectively to enhance the strength and reduce the cost, and weight of earth fill materials in geotechnical engineering led researchers to seek for modifying the soil properties by adding proper additives. Lightweight fill materials made of soil, binder, water, and Expanded polystyrene (EPS) beads are increasingly being used in geotechnical practices. This paper primarily investigates the behavior of sandy soil, modified by EPS particles. Besides, the mechanical properties of blending sand, EPS and the binder material such as fly ash and cement were examined in different mixing ratios using a number of various laboratory studies including the Modified Standard Proctor (MSP) test, the Unconfined Compressive Strength (UCS) test, the California Bearing Ratio (CBR) test and the Direct Shear test (DST). According to the results, an increase of 0.1% of EPS results in a reduction of the density of the mixture for 10%, as well as making the mixture more ductile rather than brittle. Moreover, the compressive strength, CBR value and shear strength parameters of the mixture decreases by an increase of the EPS beads, a trend on the contrary to the increase of cement and fly ash content.

• 한국주조공학회지
• /
• 제12권4호
• /
• pp.305-316
• /
• 1992

Steel and iron castings made with expandable polystylene (referred to hereafter as EPS) patterns are often affected by distinctive defects associated with incomplete decomposition of the EPS as the molds are filled with metal. The effects of practical factors on carbon pick-up were investigated on the specimens, by taking successive layers of swarf and analysis, whereas the lustrous carbon is determined by using combustion analysis. The quality of the castings, with particular reference to carbon pick-up in low carbon steel and lustrous carbon on gray iron, is further influenced to a significant extent by such practical factors as reduced pressure, the pouring temperature, the density of EPS pattern, the additive in coating and in pattern and the casting thickness. The rate at which carbon pick-up and lustrous carbon deposites are formed can be reduced by reducing the density of the pattern and also reducing pressure, especially by adding $Na_2CO_3$ in coating and in pattern to promote $CO_2$ evolution. The upper parts of castings obtained using EPS patterns are slightly higher in carbon pick-up and in lustrous carbon than other parts.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2023년도 가을학술발표대회논문집
• /
• pp.43-44
• /
• 2023

Fire doors installed to prevent the spread of fire in buildings are made of paper honeycomb, glass wool, and other materials. Due to their high water absorption rate, they absorb ambient moisture and degrade, and their increased weight causes them to sag internally, creating voids that can warp in the event of a fire and allow flames to pass through. To overcome these issues, research is being conducted on the physical performance of lightweight aerated concrete. However, there is a lack of research on how to ensure fire resistance. Therefore, in this study, the backside temperature of lightweight aerated concrete formulations was measured and compared and analyzied with the physical performance. Since it is difficult to achieve low density by saturation alone, aerated concrete with EPS was produced, which resulted in a density reduction of 24'26%, but the strength increase per unit cement increase was 5'25%, which tended to be lower than the formulation without EPS. The results showed that the lightweight aerated concrete with EPS was 130~140℃ lower than the lightweight aerated concrete with EPS, which is believed to be due to the melting point of EPS delayed the heat diffusion. In the future, wo plan to conduct research to identify the optimal formulation for fire door core materials by varying the amount of EPS added and using industrial by-products to increase long-term strength.

• 미생물학회지
• /
• 제49권3호
• /
• pp.297-300
• /
• 2013

인삼근계(근권, 근면, 근내부) 내 EPS 생성세균의 밀도를 측정한 결과, 근권토양 내에는 $2.4{\times}10^6$ CFU/g, 근면에는 $9.1{\times}10^6$ CFU/g, 그리고 근내부에는 $2.0{\times}10^4$ CFU/g로 확인되어 다수의 EPS 생성세균이 분포하고 있음이 확인되었다. 인삼 근계로부터 EPS 생성 우수 균주 24균주를 순수분리하고 계통학적 특성을 확인한 결과, 근권(RS)으로부터 분리된 EPS 생성세균은 Arthrobacter 속 6균주, 그리고 Rhizobium 속 1균주로 나타났다. 근면(RP)으로 부터 분리된 EPS 생성세균은 Arthrobacter 속 6균주, Rhodococcus 속 1균주, Pseudomonas 속 1균주로 나타났다. 근내부(IR)에서 분리된 EPS 생성세균은 Rhizobium 속 6균주, Bacillus 속 1균주 그리고 Rhodococcus 속 1균주, Pseudomonas 속 1균주로 나타났다. 근권과 근면에서 분리된 EPS 세균 중 Arthrobacter 속에 속하는 균주는 가장 특징적인 세균으로 밝혀졌으며, Rhizobium 속은 근내부에서 분리된 가장 특징적인 EPS 생성세균으로 나타났다. EPS 생성 우수균주 Rhizobium sp. 1NP2 (KACC 17637)는 10 g/L 그리고 Arthrobacter sp. 5MP1 (KACC 17636)는 4.9 g/L의 다당을 생성하였으며, 당단백질의 구성당 성분을 확인한 결과, galactose, glucose, mannose를 구성하고 있었으며, glucosamine의 아미노당이 나타났다. 특히, glucose는 72.7-84.9%로 주요 구성당임이 확인되었다.

• 한국건설순환자원학회논문집
• /
• 제11권3호
• /
• pp.210-217
• /
• 2023

Various performances of ultra-high performance concrete (UHPC) applied with microplastics and expanded polystyrene (EPS) beads were evaluated. CompressIve and flexural strength, performance after ignition, flow-down in fresh state, and effective bond strength were evaluated. Designed weight of the cement panel with these mixtures was calculated based on the flexural strength. As a result of the experiments, it was confirmed that the EPS could reduce the density of UHPC with largest range. By maximum addition of EPS beeds, the density of UHPC decreased to 1300 kg/m³, and the compressive and flexural strengths for this mixtures were in ranges of 20-30 MPa and 15-20 MPa, respectively. On the other hand, lightest cement panel could be designed with UHPC having a density ranges about 2.0 g/cm³.

• 미생물학회지
• /
• 제46권3호
• /
• pp.278-285
• /
• 2010

국내에 자생하는 당귀, 삽주, 쇠무릎, 지모, 황기의 근권토양내 EPS 생성균주의 분포율을 조사한 결과 당귀로부터 분리된 균주의 56%가 EPS 생성 균주로 가장 높은 분포율을 나타내었다. 또한, 당귀 근계 (근권, 근면, 근 내부) 내 EPS 생성 세균의 밀도를 측정한 결과, 근권 토양 내에는 $9.0{\times}10^6$ CFU/$g{\cdot}soil$, 근면에는 $7.0{\times}10^6$ CFU/$g{\cdot}soil$, 그리고, 근 내부에는 $1.4{\times}10^3$ CFU/$g{\cdot}soil$로 확인되어, 다수의 EPS 생성 세균이 분포하고 있음이 확인되었다. 당귀 근권으로부터 분리된 EPS 생성세균은 Alphaproteobacteria (4 strains), Betaproteobacteria (6 strains), Firmicutes (2 strains), Actinobacteria (3 strains), 그리고 Bacteroidetes (1 strain) 계통군에 속하는 균주였다. 근면으로 부터 분리된 EPS 생성세균은 Alphaproteobacteria (7 strains), Betaproteobacteria (3 strains), Actinobacteria (2 strains), Bacteroidetes (3 strains), 그리고 Acidobacteria (1 strain) 계통군으로 나타났으며, 근 내부에서 분리된 EPS 생성세균은 모두 Bacteroidetes 계통군 Chitinophaga에 속하는 특징을 나타내었다. 약초 근권토양으로부터 분리된 EPS 생성세균 112균주중에서 Burkholderia caribiensis DR14 (1,547 mpa.s), Terriglobus sp. DRP35균주(2,136 mpa.s), Rhizobium hainanense SAP110균주(1,680 mpa.s)를 최우수 EPS 생성 균주로 선발하였다. 분리 정제된 EPS를 Bio-LC로 분석한 결과 glucose, galactose, mannose의 중성당과, galactosamine, glucosamine의 아미노당이 나타났다. 특히 Rhizobium hainanense SAP110 균주는 주요 중성당으로 glucose (60-89%)를 그리고 주요 아미노당으로 glucosamine (8.5%)을 생성하는 특징을 나타내었다.

• 한국지반신소재학회논문집
• /
• 제9권3호
• /
• pp.57-65
• /
• 2010

본 연구의 주된 목적은 반복적인 하중조건하에서 연성포장체의노반재료로써, EPS블럭의 시간의존적 변형을 연구하는데 있다. 반복하중 조건에서의 EPS블럭의 거동을 이해하기 위해서 본 연구에서는 실험적 방법 및 수치모형을 제시하였다. 이 수치모델링을 위해서 반복하중 조건하에서 관찰된 변형거동과 단위중량, 변형 그리고 적용된 하중과의 상관관계의 조사가 행해졌다. 실험결과는 핀들레이 이론과 반복하중 조건에서의 연구결과의 모델 분석등과 비교되었고, 보완된 핀들레이 모델과 본 연구에서 제시한 모델은 반복하중에서의 EPS블럭의 변형거동을 나타내는데 이용될 수 있는 것으로 기대된다.