• 한국정밀공학회지
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• 제22권3호
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• pp.130-136
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• 2005

The nondestructive evaluation system consisted of a ball indentation tester and a ultrasonic tester was developed to evaluate material properties. The relations between the parameters from test results using the system and the results of tensile and fracture toughness tests were investigated. The fracture toughness and tensile properties could be determined using the system. Some metallic materials were experimented to predict the fracture toughness and tensile properties and verify the relations between them. The predicted fracture toughness and tensile properties show a good agreement with the results obtained by conventional tests. It is found that the material properties and the material degradation can be evaluated using the nondestructive evaluation system.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표회 논문집(I)
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• pp.111-116
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• 1998

Most previous wave tests for concrete have been done to evaluate static material properties, and thus there are less works to investigate dynamic material characteristics of concrete, which should be few in Korea. The objective of this experimental work is to investigate dynamic material characteristics of concrete, such as dynamic elastic modulus, dynamic shear modulus, first resonant frequency, dynamic poisson's ratio and etc. A dynamic Signal Analyzer has been used to perform the wave analysis for various dynamic material properties of test specimen. First Fourier transform technique has been carried out on various wave data acquired by the Resonant Column method, which is a kind of nondestructive tests. Wave analysis has been performed based on KS F2437, which is similar to ASTM C607-71 and is identical to JIS A 1127-1976.

• 소음진동
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• 제8권5호
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• pp.900-907
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• 1998

Rubber materials are extensively used in various machine design application, mainly for vibration/shock/noise control devices. Over the years an enormous effort has been put into developing procedures to provide properties of rubber material for design function. However, there are still a lot of difficulties in the understanding of dynamic characteristics of the rubber components in compression. In this paper, the dynamic characteristics of rubber materials for anti-vibration under compression were investigated. Dynamic and static tests for rubber material with 3 different hardness were performed. In dynamic tests, non-resonance method, impedance method, was used to obtain the complex modulus(storage modulus and loss factor) and the effects of static pre-strain on the dynamic characteristics were investigated. Also, a relation equation between linear dynamic and nonlinear static behavior of rubber material was discussed and its usefulness to predict their combined effects was investigated.

• 한국도로학회논문집
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• 제14권5호
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• pp.85-91
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• 2012

PURPOSES: In this study, various laboratory tests were performed to investigate the suitability of wasted vinyl as a modifier of asphalt binder. METHODS: Based on the ASTM specification, variations in material properties of asphalt binder such as penetration, flash point, softening point, ductility, penetration index (PI), and performance grade (PG) with vinyl content were tested and analyzed. RESULTS: Lavoratory tests revealed that penetration and ductility of the asphalt binder increased with the vinyl content. The flash point, softening point, and PI decreased, and PG changed from 64-22 to 70-22 with increase of the vinyl content. CONCLUSIONS: Wasted vinyl modified the material properties of the asphalt binder. However, the asphalt binder with vinyl content over 6.0% was unsuitable as a pavement material.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1175-1180
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• 2008

This study explored the compacition characteristics of organic weathered soils. Weathered soils were collected around the Gwangju University in Jinwol-dong, Gwangju city, and coal was used as organic material. Weathered soils were mixed with coal so that the ratio of organic elements against mixed soil can be 0%, 25%, 50%, and 75% respectively. Compaction tests were carried out on these organic mixture soils in different ratios of organic materials. And soap water instead of water in compaction tests was used. Through this study, We knew that the bigger the organic material ratio was, the more the optimum moisture content increased and the less the maximum dry unit weight reduced. In case of using small compaction energy, using soap water instead of water improved the compaction efficiency a little.

• Nuclear Engineering and Technology
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• 제55권10호
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• pp.3581-3590
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• 2023

High-temperature design evaluations were conducted on Type 316L stainless steel piping for a 700 ℃ large-capacity thermal energy storage verification test loop (TESET) under construction at KAERI. The hot leg piping with sodium coolant at 700 ℃ connects the main components of the loop heater, hot storage tank, and air-to-sodium heat exchanger. Currently, the design rules of ASME B31.1 and RCC-MRx provide design procedures for high-temperature piping in the creep range for Type 316L stainless steel. However, the design material properties around 700 ℃ are not available in those rules. Therefore, a number of material tests, including creep tests at various temperatures, were conducted to determine the insufficient material properties and relevant design coefficients so that high-temperature design on the 700 ℃ piping may be possible. It was shown that Type 316L stainless steel can be used in a 700 ℃ high-temperature piping system of Generation IV reactor systems or a renewable energy systems, such as thermal energy storage systems, for a limited operation time.

• 한국공간구조학회논문집
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• 제11권4호
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• pp.101-108
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• 2011

유리강회플라스틱(GRP)은 재료의 자중에 비해 아주 높은 강도를 가지고 있다. 또한 부재의 두께에 따라서 투명 혹은 반투명의 효과를 거둘 수 있다. 하지만 Hand laminating의 특성상 일률적인 재료의 강도를 선뢰하기 어렵기 때문에 구조 계산 혹은 설계 시 반드시 재료 실험을 수행하여야한다. 본 논문은 두께 4mm, 높이 30m의 의장적 기둥을 구조적으로 설계하기 위한 재료 실험을 수행하였다. 또한 실험 결과에 대한 평가를 통해 DIN에서 규정하는 재료적인 강도와 비교 분석하였다. 이를 통해 규준에서 제시하는 값과의 차이를 확인했으며 실제 설계에 반영하기 위해 반드시 재료실험이 수행되어야함을 알 수 있다.

• Geomechanics and Engineering
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• 제21권4호
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• pp.315-326
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• 2020

The long-term behavior of rockfill material used in the construction of infrastructures such as dams is of great significance. Because of concerns about the application of weak rockfill material in dam construction, further experimental studies on the behavior of these materials are required. In this study, laboratory experiments were performed to investigate the one-dimensional deformation and particle breakage of the weak rockfill material under stress. A one-dimensional compression apparatus was designed and developed for testing of rockfill materials of different maximum particle sizes (MPSs). The compression tests were performed under dry, wet and saturated conditions on samples of rockfill material obtained from a dam construction site in Iran. The results of the experiments conducted at the specimen preparation stage and the 1D compression tests are presented. In weak rockfill, the effect of the addition of water on the behavior of the material was uncertain as there were both an increases and decreases observed in particle breakage. Increasing the MPS of the weak rockfill materials increased particle breakage, which was similar to the behavior of strong rockfill material. In all of the MPSs examined, the settlement of specimens under wet conditions was higher than that observed under dry conditions. Also, the greatest deformation occurred during the first hour of loading.

• Geomechanics and Engineering
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• 제31권3호
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• pp.305-318
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• 2022

Permeable reactive barriers used for groundwater treatment require proper estimation of the reactive material behavior regarding the emplacement method. This study evaluates the dry emplacement of zeolite (clinoptilolite) to be used as a reactive material in the barrier by carrying out several geotechnical laboratory tests. Dry zeolite samples, exhibited higher wetting-induced compression strains at the higher vertical stresses, up to 12% at 400 kN/m². The swelling potential was observed to be limited with a 3.5 swell index and less than 1% free swelling strain. Direct shear tests revealed that inundation reduces the shear strength of a dry zeolite column by a maximum of 10%. Falling head permeability tests indicate decreasing permeability values with increasing the vertical effective stress. Regarding self-loading and inundation, the porosity along the zeolite column was calculated using a proposed 1D numerical model to predict the permeability with depth considering the laboratory tests. The calculated discharge efficiency was significantly decreased with depth and less than 2% relative to the top for barrier depths deeper than 20 m. Finally, the importance of directional dependence in the permeability of the zeolite medium for calibrating 2D finite element flow analysis was highlighted by bench-scale tests performed under 2D flow conditions.

• 한국지반공학회논문집
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• 제18권5호
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• pp.229-236
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• 2002

본 논문은 실용화된 지반개량용 마이크로시멘트 및 보통포틀랜드시멘트의 주입특성에 관한 연구로서 기초물성, 고결율, 침투성과 같이 실험적으로 주입재의 입도와 다짐정도를 조정하고, 주입대상 토사지반의 투수계수를 3종류로 변화시컥 약액주입의 주요 특성을 검토한 것이다. 주입재의 적용성을 평가하기 위하여 고결성 시험 및 침투성 시험을 실시한 결과, 모형토사지반의 상대밀도에 따른 투수계수를 $10^{-4}$~$10^{-2}$cm/sec로 변화시킨 경우, 마이크로시멘트는 투수 계수 $10^{-4}$cm/sec에서 유효고결율 75%, 침투주입율 86%로서 침투성 및 고결성이 우수한 결과를 나타낸 반면, OPC는 $10^{-2}$cm/sec에서 유효고결율 및 침투주입율이 50% 미만으로서 원활한 침투주입이 될 수 없음을 알 수 있었다. 댐 기초 지반 및 연약지반의 보강을 위해 주입재의 침투성이 요구되는 경우에는 마이크로시멘트가 적용성이 매우 우수한 것으로 판단된다. 동수지중 모형시험 결과 유속이 상대적으로 느린 경우 주입압이 높을수록, 완결형 주입재가 고결효과가 우수한 반면, 유속이 빠른 경우에는 완결형의 경우 주입재의 대부분이 외부로 유출되는 등 유효고결율이 매우 낮아 고결효과가 불량함을 알 수 있었다.