• 한국도로학회논문집
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• 제16권1호
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• pp.21-30
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• 2014

PURPOSES : Evaluation of input parameters determination procedure for dynamic analysis of aggregates in DEM. METHODS : In this research, the aggregate slump test and angularity test were performed as fundamental laboratory tests to determine input parameters of spherical particles in DEM. The heights spreads, weights of the simple tests were measured and used to calibrate rolling and static friction coefficients of particles. RESULTS : The DEM simulations with calibrated parameters showed good agreement with the laboratory test results for given dynamic condition. CONCLUSIONS : It is concluded that the employed calibration method can be applicable to determine rolling friction coefficient of DEM simulation for given dynamic conditions. However, further research is necessary to connect the result to the behavior of aggregate in packing and mixing process and to refine static friction coefficient.

• 한국공간구조학회논문집
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• 제15권3호
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• pp.95-102
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• 2015

Numerical model on precast prestressed concrete (PC) hollowcore slabs using 11.3 mm diameter 7-wire stand was developed based on finite element analysis. In order to validate the modelling, previous experiment results with respect to prestressed solid concrete slabs were used and compared throughout the course of fire exposure. In addition to, the fire performance of hollowcore slabs with different aggregate types, moisture contents and compressive strength of concrete was investigated. As a result, it can be seen that the type of aggregates and moisture contents used in hollowcore slabs can affect the fire performance as well as temperature developments.

• 한국콘텐츠학회논문지
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• 제17권1호
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• pp.233-241
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• 2017

세계은행에서 매년 배포되는 비즈니스 실행편의성 보고서는 경제단위별로 중소기업의 비즈니스 활동을 향상시키고 제약하는 규제들을 비즈니스 수명주기의 10개 분야(평가요소)별로 측정하고, 이를 바탕으로 분야별 및 종합 점수와 순위를 산출한다. 이 종합 점수는 10개 분야별 점수를 모두 더한 것으로, 모든 분야별 점수가 동일한 비중을 가지고 있는 것을 의미한다. 사용하는 평가요소와 가중치에 따라서 평가 결과가 크게 달라질 수 있기 때문에 세계은행의 보고서가 우리나라 기업들이 중요시하는 평가요소들을 제대로 반영하지 못한 것일 수 있고, 그 결과를 직접 활용하기 어려운 측면이 있다. 이 논문에서는 대한민국 중소기업의 관점에서 이들 10개 평가요소의 가중치를 산정하여 경제단위의 비즈니스 실행 편의성을 비교하고자 한다. 국내 경영학부 교수 및 중소기업 CEO를 대상으로 AHP 기반의 설문을 실시하여 평가요소별 가중치를 산정하고, 이를 2016년 세계은행 보고서 자료에 적용하여 종합 점수와 순위를 산출하였다. 상위권과 하위권에서는 변화가 상대적으로 적었던 반면에, 중위권에서는 큰 변화가 나타나는 경우들도 확인되었다.

• 한국도로학회논문집
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• 제17권2호
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• pp.89-98
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• 2015

PURPOSES : The objective of this study is to evaluate the performance properties of chip seals and fog seals with polymer-modified emulsions. METHODS : The performance of chip seals and fog seals was evaluated on the basis of common issues in surface treatments. Granite aggregate and four types of asphalt emulsions (one of the unmodified and three of the modified emulsions) were used considering the usage in field. A Vialit test was performed to determine the aggregate retention, and the MMLS3 (Third Scale Model Mobile Load Simulator) test was conducted to determine the aggregate retention, bleeding, and rutting. In addition, the fog seal specimens were tested by the BPT (British Pendulum Test) to evaluate skid resistance. RESULTS AND CONCLUSIONS : Overall, the polymer-modified emulsions (PMEs) showed better aggregate retention and bleeding resistance for both chip seals and fog seals. When comparing the performance of the PMEs, the difference was not considerable. In addition, PMEs present significantly better rutting resistance than unmodified emulsions. For skid resistance, if the recommended mix design is applied, the specimens do not cause issues with skid resistance. Although all of the fog seal specimens were over the criteria for skid resistance, the specimen fabricated by the high emulsion application rate (EAR) of the unmodified emulsion was nearly equivalent to the skid value criteria. Therefore, the use of an unmodified emulsion with a high EAR should be carefully applied in the field.

• 한국건설순환자원학회지
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• 제7권2호
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• pp.11-14
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• 2012

• 한국건설순환자원학회지
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• 제7권2호
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• pp.15-18
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• 2012

• 복합신소재구조학회지
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• 제6권2호
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• pp.31-39
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• 2015

• 한국건설순환자원학회지
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• 제18권1호
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• pp.73-77
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• 2023

• 한국유체기계학회 논문집
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• 제19권3호
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• pp.43-47
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• 2016

Pile foundations constructed on extremely cold regions cause serviceability problems of superstructures from repeated actions of ground freezing and thawing. Oil sand module plants are mainly constructed on seasonal frozen ground. Due to the freezing and thawing actions of grounds, vertical movements of piles have been observed. To solve these erratic pile movement problems, thin vertical layer of PET aggregates is installed around the pile shaft to prevent potential unfavorable pile movements. There is no known method to calculate "thin PET aggregate layer" -surrounded pile shaft resistance (capacity) against vertical loads; therefore, this experimental research is conducted. Specifically, in this study, horizontal (normal) pressures on pile shaft were assessed varying PET aggregate layer thickness based on the experiment.

• 콘크리트학회논문집
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• 제12권6호
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• pp.91-98
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• 2000

Porous concrete having continuous voids is gaining more interest as an ecological material. It has several useful functions such as water and air permeability, sound absorption, etc. Its strengths are considerably lower than those of conventional concrete due to the large and continuous voids in it. This study has been carried out to investigate the influence of mix factors and mixture proportion of aggregate on the strengths and water permeability of porous concrete. And it has been carried out to investigate the evaluation of void of porous concrete by the ultra-sonic pulse velocity. The results f this study are as follows: 1) The theoretical void ratio has greater influence than any other factor on the strengths and water permeability of porous concrete. And it is a little affected by the replacement proportion of silica-fume and mixture proportion of aggregate. 2) Because the coefficients of correlation between the void ratio and ultra-sonic pulse velocity were relatively high, it will be possible that the void ratio is predicted by the ultra-sonic pulse velocity.