• 한국도로학회논문집
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• 제11권2호
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• pp.133-139
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• 2009

콘크리트 도로에서 줄눈의 역할은 계절적 온도변화에 따라 콘크리트 슬래브의 수축과 팽창 시 적절한 공간을 확보하여 파손과 균열을 보호하는 역할을 하게 된다. 이때 줄눈 부위를 줄눈재로 채워 넣어 이물질이 침투하여 슬래브의 움직임을 방해하거나 파손시키는 것으로부터 보호하는 역할과 강우나 강설 등에 의한 수분이 포장 내부로 침투하여 동결융해에 의한 내부균열 방지 및 다웰바 등을 부식시키는 것을 막는 역할을 수행하여 도로의 공용성을 향상시키는 역할을 하게 된다. 본 연구에서는 콘크리트 도로 줄눈에서 시공된지 2년 경과한 시료를 채취하여 열화를 겪지 않은 초기시료와의 물리적 강도, 내후성, 제설제 저항성 등으로 평가하였으며 실리콘 소재 대비 내후성과 접착성에 큰 차이가 발생하는 것을 확인하였다.

• 한국도로학회논문집
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• 제14권4호
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• pp.73-81
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• 2012

PURPOSES : The purpose of this study is to select the proper sealing method and to see the performance of the saw and seal method for concrete rehabilitation based on accelerated pavement testings and lab tests. METHODS : Two accelerated pavement testings were conducted. One is to select proper sealing method of the asphalt joints and the other is to see the performance of the saw and seal method. Lab tests were conducted to select proper sealing method and a test section was constructed to see the field performance. RESULTS : The result of the first accelerated pavement testing indicated that the adhesive preformed sealants showed good performance when asphalt layer was rutted and in terms preventing from water infiltration. The second acceleration test indicated that the saw and seal method using the adhesive preformed sealant showed much better performance than the control. In the lab test bitumen, rubber and epoxy showed good performance as the adhesive. CONCLUSIONS : Saw and Seal method using the adhesive preformed sealant would markedly reduce the joint damage on the asphalt overlay.

• 접착 및 계면
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• 제7권4호
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• pp.24-27
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• 2006

International standards claim the best possible reliability in industrial manufacturing processes. This is also essential for the application with manual applicators. The application of adhesives with manual applicators is one of the most frequently used application techniques. The range of application reaches from the building of prototypes in the automobile industry over the use in single or small-batch manufacturing up to applications in crafts enterprises. Conventional manual applicators for adhesives and sealants don't fulfill the demands in international standards for the best possible reliability. Only the worker is able to control the quality and the quantity of the bond. A velocity-controlled manual applicator solves these restrictions. Special sensors and micro controllers calculate the flow-rate, the velocity and the location of the manual applicator. This leads to stable and repeatable application processes which are claimed in international standards. The location of the bond can be compared with the nominal value, so that it is possible to check the quality of the bond during application. Furthermore there is the potential to document the data of the manufacturing process.

• 한국재료학회지
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• 제26권10호
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• pp.521-527
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• 2016

Geopolymers have many advantages over Portland cement, including energy efficiency, reduced greenhouse gas emissions, high strength at early age and improved thermal resistance. Alkali activated geopolymers made from waste materials such as fly ash or blast furnace slag are particularly advantageous because of their environmental sustainability and low cost. However, their durability and functionality remain subjects for further study. Geopolymer materials can be used in various applications such as fire and heat resistant fiber composites, sealants, concretes, ceramics, etc., depending on the chemical composition of the source materials and the activators. In this study, we investigated the thermal properties and microstructure of fly ash and blast furnace slag based geopolymers in order to develop eco-friendly construction materials with excellent energy efficiency, sound insulation properties and good heat resistance. With different curing times, specimens of various compositions were investigated in terms of compressive strength, X-ray diffraction, thermal property and microstructure. In addition, we investigated changes in X-ray diffraction and microstructure for geopolymers exposed to $1,000^{\circ}C$ heat.

• Journal of Chest Surgery
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• 제28권6호
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• pp.557-564
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• 1995

Microvel knitted double velour vascular grafts coated with biodegradable algin were evaluated in the canine experimental model as a new biologically coated Dacron graft. Three series of implantations were conducted involving the insertion of 6 mm diameter grafts in the abdominal aortae of mongrel dogs. The first series used the regular Microvel vascular grafts coated with algin,whereas the second and third series used Hemashield [collagen-coated grafts and the regular Microvel grafts with preclotting,respectively as control groups. Each series involved the implantation of one prosthesis for each of 2 preselected periods,namely 3 months and 6 months. In addition,algin-impregnated grafts were implanted for 4 hours,72 hours,2 weeks,and 4 weeks. All grafts were patent when the animals were sacrificed at intervals ranging from 4 hours to 6 months. Histological examinations revealed no obvious or significant differences in the healing characteristics of the algin-coated grafts and the control grafts after 3 months and 6 months of implantation. Endothelial cell-like cells were present on the midsegments of all grafts explanted from animals sacrificed after 3 months and 6 months,except a suspicious finding in the 3 month-implantation animal of a preclotted graft. With special stains,the algin became invisible between the polyester filaments during the first 3 months of implantation. This study has demonstrated that the use of a biodegradable algin coating is a feasible approach as biological sealants for textile arterial prostheses.

• 신재생에너지
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• 제3권3호
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• pp.5-13
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• 2007

Stacks of solid oxide fuel cell with 1kW max power performance were designed on planar type employing anode-supported cells and metallic interconnects. The stacks composed of 3-cells, 8-cells, and 16-cells were fabricated and tested in serials by using anode-supported cells purchased from Indec, and sealants/interconnects prepared at RIST. In the performance test of the final 16-cells stack, OCV was recorded to be 16.7V. The peak power and the power density showed 1 kW, $0.77W/cm^2$ at $820^{\circ}C$, respectively. In addition, the long-term degradation rate of the power exhibited 2.25 % during 500h at $750^{\circ}C$.

• 한국전기전자재료학회논문지
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• 제20권3호
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• pp.273-280
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• 2007

In this paper, the ZnO surge arrester performance of power distribution class has been studied under different manufacturing conditions such as housing materials(polymeric, porcelain), interface sealants and one-body molding type. In the recent years, the polymeric ZnO surge arresters have been developed and put into operations based on their excellent characteristics. For polymeric surge arresters, the inner gas volume is extremely small, especially in solid insulation polymeric arresters there are not any gas volume inside arresters in the structure due to polymeric materials are filled into the internal gas volume. The sealing integrity is related to safe operation of surge arrester, the prime failure reason of porcelain housed arresters is moisture ingress. In this paper, the sealing integrity of polymeric surge arresters is investigated with moisture multi-aging test and ingress test. The evaluation techniques are used to inspect the sealing integrity of polymeric arresters, including leakage current, surface temperature, reference voltage and dissipation factor.

• 한국도로학회논문집
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• 제11권3호
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• pp.33-40
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• 2009

폐타이어 고무분말은 도로 유지 및 보수제로 아스팔트 바인더의 개질제로 사용되고 있다. 도로보수제인 폐타이어 고무분말 개질 아스팔트 (crumb rubber modified asphalt, CRMA) 실란트에 필요한 접착특성은 저온에서 아스팔트 바인더의 취성과 접착파괴특성 때문에 주목받고 있다. 본 연구에서는 저온에서 CRMAs의 개질제로서 유연제의 영향을 조사하였다. 저온에서 CRMAs의 특성은 침입도, 연화점, 인장 및 인장접착시험을 통하여 측정하였다. 유연제를 도입한 CRMAs에서 CR과 아스팔트바인더의 연성변형이 증가함에 따라 인장접착강도와 변형률이 증가하였다. 저온영역에서 CRMAs의 인장특성과 접착특성은 유연제의 함량이 중요한 요소임을 발견하였다.

• 한국치위생학회지
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• 제15권6호
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• pp.999-1007
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• 2015

Objectives: The objective of the study is to investigate oral health behavior and oral health education experience in Korean adolescents from the ninth(2013) web-based survey of Korean youth risk behavior. Methods: The subjects were 72,435 students through the ninth 2013 web-based survey of Korean youth risk behavior conducted by the Ministry of Education, Science, and Technology, the Ministry of Health and Welfare, and the Korea Centers for Disease Control. The questionnaire consisted of socio-demographical characteristics of the subjects, oral health behavior, and oral health education experience. Data were analyzed by SPSS 18.0 program. Results: Oral health education had much influence on tooth brushing after lunch, oral cavity disease prevention, sealants, fluoride application, scaling experience, and consumption of vegetables, milk, carbonated soft drinks, noodles, and snacks. The oral health education had a great impact on those who took good oral health behavior into action. Conclusions: It is very important and necessary to develop the continuing effective oral health education program for the adolescents and make them tale into action.

• Corrosion Science and Technology
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• 제12권4호
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• pp.191-197
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• 2013

This study is the second stage of developing the corrosion control technical manual about unpainted weathering steel bridge with closed box girder structures. This paper contains selection of corrosive sealant to apply into crevice of upper flange, injecting test of sealant at mock-up equipment with various condition, evaluation of experiment result. Through the experiment of injection of sealants into crevice of mock-up equipment, it is proved that the tar sealant injecting corrosion control method is useful to protect corrosion at box girder upper flange corroded by remaning rain water with calcium chloride.