• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.176-179
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• 2003

Fuel oxygenates, such as Methyl tertiary Butyl Ether (MTBE) is additive in gasoline used to reduce air pollution. Gasoline components and fuel additives can leak form underground storage tanks. MTBE is far more water soluble than gasoline hydrocarbons like BTEX then it travels at essentially the same velocity as groundwater. MTBE in drinking water causes taste and odor problems. Therefore, the purpose of the this study is to examine the ability of ground rubber to sorb MTBE form water. The study consisted of running both batch and column tests to determine the sorption capacity and the flow through utilization efficiency of ground rubber. The result of Column test indicate that ground tire rubber has on the 36% utilization rate. Finally, it is clear that ground rubber present an attractive and relatively inexpensive sorption medium for a MTBE. The Author thought that to determine the economic costs of ground rubber utilization, the cost to sorb a given mass of contaminant by ground rubber will have to be compared to currently accepted sorption media.

• 아시안잔디학회지
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• 제16권1호
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• pp.19-30
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• 2002

경직된 지반의 물리성 개선재로서 rubber chip의 토양 내 혼합 또는 배토는 잔디의 생육과 지반의 이·화학성 및 중금속 추출 실험을 통하여 다음과 같은 결론을 얻었다. Rubber chip의 토양 내 혼합은 지면의 온도 상승효과를 가져왔으며 이는 겨울철의 동해방지 및 맹아출현기를 앞당길 수 있을 것이라 추정된다. 그러나 복사열이 높은 여름에는 rubber chip에 의한 표면, 지중 온도의 상승으로 잔디의 피해가 우려된다. 또한 토양 내에 rubber chip의 혼합함량(rubber chip 20%, 40%)이 많을수록 잔디의 발아와 생육 및 피복에 부정적인 영향을 끼쳤다. Rubberchip의 토양혼합은 지반의 이·화학성 변화에 크게 작용하지 않았으며 중금속 추출실험에서도 차이를 나타내지 않아 토양환경 오염이 없을 것으로 판단된다. Rubber chip을 배토용 재료로서 사용했을 경우, 경직된 토양구조를 개선시켜 주었다. 특히 통기작업 후 rubber chip의 배토는 지반의 표면탄성을 현저히 완화시켰다. 따라서 현재 우리나라에서 보수중이 거나 건설중인 연습구장, 보조구장에 재활용이 가능한 폐타이어 rubber chip을 지반 답압 개선용, 배토용 재료로서 사용이 가능할 것으로 판단된다.

• Elastomers and Composites
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• 제39권4호
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• pp.294-300
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• 2004

혼합폐플라스틱과 폐타이어분말을 혼합하여 복합체를 구성하고 그 기계적인 물성을 조사하였다. 수지-고무분말 사이의 계면접착력을 증대시키고자 두 요소와 친화성을 가질 것으로 예상되는 trans-octylene rubber(TOR)를 소량 첨가하였다. 고무분말의 투입량이 많아질수록 인장강도와 압축강도는 플라스틱자체보다 저하되었으며 파단신장률과 충격강도는 증가되었다. 상용화제 TOR이 첨가되면 인장강도와 충격강도 및 압축강도는 크게 향상되었으나 신장률은 변화가 없었다. 이러한 물성의 변화는 TOR의 화학적인 이중성에 기인한다고 여겨진다.

• Elastomers and Composites
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• 제35권2호
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• pp.132-137
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• 2000

EPDM 발포체 제조의 충전제로 폐타이어 분쇄고무와 카본블랙을 각각 사용하면서 가황특성 및 기계적 물성을 조사하여 이들을 비교하였다. 그 결과 충전제의 함량이 증가함에 따라 가황시간이 짧아짐을 알았다. 분쇄고무를 충전제로 사용한 경우 충전제의 함량이 30 phr 이상이 되면 발포배율, 인장강도 및 신율이 급격히 감소하였다. 반면에 카본블랙을 사용한 경우는 70 phr이 사용될 때까지 인장강도 및 신율의 급격한 변화는 없었다. 이들을 고려할 때, 분쇄고무의 사용량은 30 phr 미만으로 제한시켜야 함을 알았으며 이는 낮은 계면 접착력 때문이었다. 제조된 EPDM 발포체는 우수한 내노화성을 나타내었다.

• 전기학회논문지
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• 제62권4호
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• pp.577-583
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• 2013

We have analyzed influence of potential rise in negative bus, which caused by decrease of power feeding line insulation, upon protecting method of DC ground protection device which detecting potential rise between negative bus and ground in order to detect ground fault in the rubber wheel system. For this purpose, we proposed negative potential equation between negative bus and ground and calculated negative potential according to system condition changes by estimating power feeding line insulation changes in steel wheel system and rubber wheel system, and equalizing DC power feeding system when ground fault occurred. Also, in order to estimate negative potential of real system, we modeled the rubber wheel system, and simulated normal status, grounding fault occurrence and power feeding line insulation changes. In normal status, negative potential did not rise significantly regardless of vehicle operation. When ground fault occurred, negative potential rose up over 300V regardless of fault resistance. However, we also observed that negative potential rose when power feeding line insulation dropped down under $1M{\Omega}$. In conclusion, our result shows that in case of rubber wheel system unlike steel wheel system, relay will be prevented maloperation and insulation status observation can be ensured when ground over voltage relay will be set 200V ~ 300V.

• Macromolecular Research
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• 제16권5호
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• pp.404-410
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• 2008

In order to obtain 'value added products' from polypropylene (PP)/waste ground rubber tire powder (WGRT) composites, PP/WGRT microcellular foams were prepared via supercritical carbon dioxide. The effects of blend composition and processing condition on the cell size, cell density and relative density of PP/WGRT micro-cellular composites were studied. The results indicated that the microcellular structure was dependent on blend composition and processing condition. An increased content of waste ground rubber tire powder (WGRT) and maleic anhydride-grafted styrene-ethylene-butylene-styrene (SEBS-g-MA) reduced the cell size, and raised the cell density and relative density, whereas a higher saturation pressure increased the cell size, and reduced the cell density and relative density. With increasing saturation temperature, the cell size increased and the relative density decreased, whereas the cell density initially increased and then decreased.

• Elastomers and Composites
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• 제38권2호
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• pp.103-121
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• 2003

The application of powerful ultrasound to rubber recycling is a very recent field of study. An ultrasonic field creates high frequency extension-contraction stresses by acoustic cavitation. The breakdown of rubber network occurs primarily around pulsating cavities due to the highest level of strain produced by high-power ultrasound. Stronger reductions of cross-link density were observed at a higher pressure, indicating an important role of pressure during ultrasonic recycling. Visible bubbles were observed during ultrasonic treatment as a proof of acoustic cavitation. Shearing effect has a significant influence on improving the efficiency of ultrasonic treatment. After the ultrasonic treatment, the cross-link densities of NR/SBR blends were lower than those of NR and SBR due to the reduced degree of unsaturation and chemical reactions. Carbon black fillers increase the probability of bond scission during ultrasonic treatment, due to the restricted mobility. The mechanical properties of ground tire rubber (GRT)/HDPE blends were improved by ultrasonic treatment and dynamic revulcanization. Ultrasonic treatment of GRT in the presence of HDPE matrix was found to give better mechanical properties due to the chemical reactions between rubber and plastic phases.

• Nuclear Engineering and Technology
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• 제46권5호
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• pp.605-618
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• 2014

The effects of variability of the mechanical properties of lead rubber bearings on the response of a seismic isolation system are investigated. Material variability in manufacturing, aging, and operation temperature is assumed, and two variation models of an isolation system are considered. To evaluate the effect of ground motion characteristics on the response, 27 earthquake record sets with different peak A/V ratios were selected, and three components of ground motions were used for a seismic response analysis. The response in an isolation system and a superstructure increases significantly for ground motions with low A/V ratios. The variation in the mechanical properties of isolators results in a significant influence on the shear strains of the isolators and the acceleration response of the superstructure. The variation provisions in the ASCE-4 are reasonable, but more strict variation limits should be given to isolation systems subjected to ground motions having low A/V ratios. For application of seismic isolation systems to safety-related nuclear structures, the variation in the material and mechanical properties of the isolation system should be properly controlled during the manufacturing and aging processes. In addition, special consideration should be given to minimize the accidental torsion caused by the dissimilarity in the stiffness variations of the isolators.

• Earthquakes and Structures
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• 제7권6호
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• pp.1141-1169
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• 2014

This study is aimed to investigate the seismic performance of low-rise precast wall system with base isolation. Three types of High Damping Rubber Bearing (HDRB) were designed to provide effective isolation period of 2.5 s for three different kinds of structure in terms of vertical loading. The real size HDRB was manufactured and tested to obtain the characteristic stiffness as well as damping ratio. In the vertical stiffness test, it was revealed that the HDRB was not an ideal selection to be used in isolating lightweight structure. Time history analysis using 33 real earthquake records classified with respective peak ground acceleration-to-velocity (a/v) ratio was performed for the remaining two types of HDRB with relatively higher vertical loading. HDRB was observed to show significant reduction in terms of base shear and floor acceleration demand in ground excitations having a/v ratio above $0.5g/ms^{-1}$, very much lower than the current classification of $0.8g/ms^{-1}$. In addition, this study also revealed that increasing the damping ratio of base isolation system did not guarantee better seismic performance particularly in isolation of lightweight structure or when the ground excitation was having lower a/v ratio.

• Macromolecular Research
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• 제13권1호
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• pp.30-38
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• 2005

Sulfur-cured gum natural rubber vulcanizates were devulcanized using two different concentrations of diallyl disulfide. The devulcanization process was performed at $110^{\circ}C$ min in an open two-roll cracker-cum-mixing mill. Natural rubber vulcanizates having various sulfur/accelerator ratios were used to study the cleavage of monosulfide, disulfide, and polysulfide bonds. The properties of devulcanized natural rubber increased upon increasing the disulfide concentration and the mechanical properties of the revulcanized natural rubber increased upon decreasing the sulfur content in the original rubber vulcanizates. The scorch time and the maximum state of cure both increased when the ground vulcanizates were treated with higher amounts of disulfide. TGA and DMA were conducted to study the effects of the devulcanization on the thermal stability and the $T_g$ behavior of the vulcanizates. SEM analysis was conducted to study how the failure mechanism was affected by the devulcanization process. It was possible to recover $70-80\%$ of the original gum rubber properties by using this process. From IR spectroscopic analysis, we observed that the oxidation of the main chains did not occur during high-temperature milling.