• Tunnel and Underground Space
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• v.29 no.6
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• pp.532-541
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• 2019

Even though shotcrete is a main support for securing the stability of tunnel, the performance of shotcrete is not properly checked due to various difficulties arisen from the characteristics of materials themselves which constitute shotcrete, such as steel fibers and accelerators, and the on-site quality control. In this study, the actual conditions of shotcrete applied to expressway tunnel construction sites were tried to find out, and then some improvement was tried to derive. For this purpose, the characteristics of steel fibers and accelerators supplied to the expressway construction sites were investigated. Also, shotcrete specimens were prepared at the tunnel sites and performance tests were carried out. For steel fiber, domestic production states were investigated, and carbon content and tensile strength were measured using the steel fibers collected in the construction sites. For three types of accelerators such as aluminate, cement mineral and alkali-free, basic properties and total amount of alkali contents were analyzed. Shotcrete specimens were prepared using on-site shotcrete machine with regard to mix designs and types of accelerators. Using these specimens, uniaxial compression tests and flexural tests were performed. As the results, compressive strength, flexural strength, flexural toughness, and etc. were compared with types of acclerators and mix designs.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3D
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• pp.425-433
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• 2006

The presented work provided a predictive equation for dynamic modulus of hot mix asphalt, which showed higher reliability and more simplicity. Lots of test result by UTM at laboratory has been used to develop the precise predictive equation. Evaluation of dynamic modulus for 13mm and 19mm surface course and 25mm of base course of hot mix asphalt with granite aggregate and two asphalt binders (AP-3 and AP-5) were carried out. Superpave Level 1 Mix Design with gyrator compactor was adopted to determine the optimum asphalt binder content (OAC) and the measured ranges of OAC were between 5.1% and 5.4% for surface HMA, and around 4.2% for base HMA. The dynamic modulus and phase angle were determined by testing on UTM, with 5 different testing temperature (-10, 5, 20, 40, & $55^{\circ}C$) and 5 different loading frequencies (0.05, 0.1, 1, 10, 25 Hz). Using the measured dynamic modulus and phase angle, the input parameters of Sigmoidal function equation to represent the master curve were determined and these will be adopted in FEM analysis for asphalt pavements. The effect of each parameter for equation has been compared. Due to the limitation of laboratory tests, the reliability of predictive equation for dynamic modulus is around 80%.

• Elastomers and Composites
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• v.14 no.4
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• pp.260-263
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• 1979

티오디에탄올을 기본(基本)으로 하는 신합성(新合成)고무의 사용온도범위(使用溫度範圍)는 $-65^{\circ}C$에서 $150^{\circ}C$이며 표준연료(標準燃料) C와 gasohol을 포함(包含)한 각종(各種) 자동차용(自動車用) 오일에 대하여 우수(優秀)한 내유성(耐油性)을 보였고, 이 외(外)에 자연(自然)에서 널리 발생(發生)되는 황화수소(黃化水素)가스에 대(對)하여서도 우수(優秀)한 내(耐)가스성(性)을 보였다. 이 TDE 탄성체(彈性體)의 배합(配合)은 종래(從來)의 2본(本) 로울러 또는 밀폐식(密閉式) 혼합기(混合機)로 혼연(混練)할 수 있으며, compression, 사출(射出), 프레스 등으로 가황(加黃) 또는 유출(押出)이 가능하다. American Cyanamid Co에서는 TDE탄성체(彈性體)를 이용(利用)한 응용개발(應用開發)에 있으며 파일롯규모(親模)의 생산체제(生産體制)를 시도(試圖)할 것으로 알려져 있다. 이것이 시판(市販)되면 상품명(商品名)으로 Cymax라 명명(命名)될 것이며, 아민계(系곤) 가황제(加黃劑)인 DPP의 상품명(商品名)도 Cymax Curative P로 시판(市販)하게 될 것이다.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.10a
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• pp.59-69
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• 2005

일본의 농림수산성은 ${\ulcorner}$농업용 폐플라스틱${\lrcorner}$으로 호칭하고 있다. 연간배출량은 약 16 만톤에 이르고 있고, 이의 처리내용은 재생 38%, 매립 32%, 소각 11%, 등이다. 재생처리단계는 민간사업자가 기본으로, 처리내용은 일반적으로 PVC가 바닥재로써 쓰이고 PE가 서멀(연료)로써 쓰인다. 그러나 최근에 와서 비닐에 혼합되어 있는 이물질을 완전제거해 일정량의 버진과 배합함으로써 비닐을 반영구적으로 순환해 사용할 수 있는 기술이 개발되어 졌다. 이 싸이클시스템은 21 세기의 절약형사회에 적합한 것으로, 버진제품보다 저가에 공급되어 농업경영의 안정화에도 기여하고 있다. 한번 사용한 농업용 생산자재를 회수해 다시 생산자재로서 활용, 끝없이 순환한다는 개념이 뒷받침하는 이 기술은 향후 환경과 자원의 문제해결이라는 주목할 만한 가치가 있다.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.305-306
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• 2009

This study is on basic experimental methods of easily verifying the fiber content in non-spalling concrete at construction sites. As a result, fiber content in a mixture can be effectively measured by using 15$\ell$ of water for dilution of specimens, dry bit trowel for tool, and microwave for drying.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.1097-1100
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• 2010

지하매설물의 안전성은 뒤채움재의 시공과정 및 재료의 품질관리에 큰 영향을 받는다. 최근 지하매설물의 파손형태을 검토한 결과, 파손의 주요 원인으로 부적절한 뒤채움재 이용 및 충분하지 못한 다짐 등이 있다. 이러한 원인으로 매설물 주위의 지반침하로 인한 파손이 빈빈하게 발생하고 있다. 본 연구에서는 현장에서 발생하는 현장발생토사, 정수장처리장의 정수슬러지, 화력발전소의 플라이애쉬, 폐타이어 고무분말 등을 혼합한 유동성 뒤채움재의 최적배합설계 및 설계에 필요한 기본적인 강도특성을 규명하였다.

• 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.211.1-211
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• 2003

식혜를 제조하는 과정에서 엿기름 추출액의 농도가 당화시간과 밥알형태 및 식혜의 관능평가에 미치는 영향 등에 대하여 조사하였다. 엿기름 추출액의 농도가 기본배합비(쌀 6g, 엿기름 7g, 물240ml)의 4배(쌀 24g, 엿기름 28g, 물 240ml)일때 당화시간 단축과 밥알 형태 유지에 가장 적합하였다. 당화된 밥알의 형태는 엿기름 추출액의 농도 및 당화시간과 당화 전 밥알형태에 의해 영향을 받는 것으로 나타났다. 당화가 완료되었을 때 보다 미량의 전분질이 남아 있을 때가 식혜의 부드러운 맛과 밥알형태 유지에 적합하였다. 밥알형태유지에 적합한 당화시간은 240분이 가장 좋았고 또한 210분과 270분에서도 적합한 것으로 나타났다. 식혜제조시 부드러운 맛과 밥알 형태를 유지하고 생산공정의 단축을 위해서는 쌀 : 엿기름 : 물을 24g : 28g ： 240m1의 비율로 제조한 후 전체의 양이 4배가 되게 약 3배의 물을 첨가하는 것이 바람직한 것으로 사료된다.

• Polymer(Korea)
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• v.25 no.1
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• pp.63-70
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• 2001

The objective of this study was to investigate the effect of cure type on the processing and physical properties under conditions of similar stress-strain properties. On the carbon black filled natural rubber(NR) based compound, the induction time decreased, but the cure rate became fast with increasing loading of sulfur donor agent. Tensile strength was little affected on the curing type. However, elongation generally decreased with increasing accelerator. Effect of cure type on the blow-out properties was followings: CV

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.456-459
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• 2011

Among the various activated carbons available in the market, an optimum mixing method of two kind activated carbons with different adsorbability was investigated in this study. The representative adsorption behaviors of the activated carbon are the adsorption isotherm plots obtained by the BET-Analysis which suggests also basic information of adsorption filter design. So we have tested three cases with certifications, the one was the extreme case of coal cokes based activated carbon with highest BET-model and coconut-shell based activated carbon with the lowest Langmuir-model, the other middle and cross case were applied this method to two kinds of activated carbons with higher and lower specific surface areas which are not available but supplied as research samples by an authority of an Korean Research Institute.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.171-184
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• 2007

Chemical admixture stabilization has been extensively used in both shallow and deep stabilization in order to improve inherent properties of the soil such as strength and deformation behavior. An increment in strength, a reduction in compressibility, an improvement of the swelling or squeezing characteristics and increasing the durability of soil are the main aims of the admixtures for soil stabilization. Recently, the various advanced cement stabilizer mixing technique was developed. Advanced cement stabilizer mixing technique is environmentally-friendly and has an excellent mixing property and outstanding mixing speed. In this study, to develop the rural road pavement technology using cement stabilizer, compaction and unconfined compression test were performed with various mixing ratio and two types of soil(clay and silty soil). And the freezing/thaw test and bending strength test performed to develop suitable cement stabilizer material for stabilization of rural road. Based on the test results, the liquid types of cement stabilizer material and silty soil mixture are most suitable for rural road construction and although the mixing ratio is low, cement stabilizer mixture is effective for durability of rural road surface layer.