• 대한금속재료학회지
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• 제49권1호
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• pp.1-8
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• 2011

To measure the sensitivity of the hydrogen embrittlement from plated high strength bolts (SWCH18A, F11T), the bolt was stressed by a corresponding to the amount of tensile strain of 5% and 20%, and then the bolt developed a crack on the surface. The bolt that didn't have concentrated hydrogen, even though it was stressed by a corresponding the amount of tensile strain of 5% and 20%, no crack developed. However, the bolt that had concentrated hydrogen, developed cracks from the thread crest to the root. It is impossible to measure the hydrogen amount from plated high strength bolts using Hydrogen-Determinator, because of the limitation of the minimum sample size (about 1g as a mass or $5{\times}5{\times}5 mm^3$ as a volume). Therefore, the sensitivity of hydrogen embrittlement can be measured by observing the presence of cracks on the surface of plated high strength bolts which are stressed by a corresponding to the amount of tensile strain of 5% and 20%.

• Restorative Dentistry and Endodontics
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• 제26권1호
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• pp.41-50
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• 2001

The purpose of this study was to examine the influences of camphoroquinone on the properties of five experimental composites. The contents of camphoroquinone were varied as 0.2%, 0.3%, 0.4%, 0.5%, and 0.6%, with silanized filler 75% and tertiary amine 0.2%. Five kinds of experimental composites were prepared, and diametral tensile strength, shear bond strength, depth of cure and yellowish discoloration were tested as a measurement. Specimen numbers of 10 were applied to all test items and experimental groups. Specimens for testing the diametral tensile strengths with internal diameter of 6mm in diameter and 3mm in height were filled with 5 experimental composites which were crushed with 1mm/min cross-head speed on Instron universal testing machine (Model No. 4467). Shear bond strength was measured on specimens attached to bovine teeth enamel etched with 37% phosphoric acid. Depth of cure was measured by the measurement of height of specimens which were removed the un-polymerized portion with acetone. Yellowness measurements were made by chromometer(Minolta Co. Japan) using L$^*$a$^*$b$^*$ values. ANOVA and Multiple range tests were used analyzed data with confidence level at 95%. The mean value of the shear bond strengths ranged from 31.03MPa to 39.49MPa. Following results were obtained ; 1. Diametral tensile strength was highest in experimental group 3, then was not affected by the contents of camphoroquinone ($r^2$=0.0422). 2. Composite resins containing 0.4% camphoroquinone showed the highest shear bond strength, but there was no statistical significance (p=0.3718). 3. Camphoroquinone reduces the depth of cure in the composite resins (p=0.0004, $r^2$=0.9483). 4. Camphoroquinone made the composites yellowish ($r^2$=0.9815). These results mean that increased content of camphoroquinone reduces the depth of cure, and that camphoroquinone make composites yellowish.

• 한국재난정보학회 논문집
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• 제13권3호
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• pp.348-357
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• 2017

본 연구에서는 생갯벌을 잔골재 대신 치환한 모르타르의 물리적 특성에 대한 실험을 진행하여 벽돌로써의 활용 가능성을 분석하였다. 플로우 측정결과 시멘트와 잔골재의 배합비가 높을수록 플로우 값이 증가하였으며, 생갯벌의 치환율이 감소할수록 플로우값이 감소하는 것으로 나타났다. 염화물 함유량 측정결과 생갯벌의 치환율이 감소할수록 염화물 함유량 또한 감소하는 것으로 나타났다. 압축강도 측정결과, 대부분의 배합비에서 생갯벌의 치환율이 감소할수록 압축강도는 반비례하여 증가하는 것으로 나타났다. 인장강도 측정결과, 압축강도와 비슷한 경향을 나타냈다. 그리고 생갯벌 치환율이 감소할수록 강도가 증가하는 것으로 나타났다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.45-48
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• 2008

The mechanical behavior of small-sized materials has been investigated for many industrial applications, including MEMS and semiconductors. It is challenging to obtain accurate mechanical properties measurements for thin films due to several technical difficulties, including measurement of strain, specimen alignment, and fabrication. In this work, we used the micro-tensile testing unit with the real-time DIC (Digital Image Correlation) strain measurement system. This system has advantages of real time strain monitoring up to 50 nm resolution during the micro-tensile test, and ability to measure the young's modulus and Poisson's ratio at the same time. The mechanical properties of SCS (Single Crystal Silicon) are measured by uniaxial tension test from freestanding SCS which are $2.5{\mu}m$ thick, $200-500{\mu}m$ wide specimens on the (100) plane. Young's modulus, Poisson's ratio and tensile strength in the <110> direction are measured by micro-tensile testing system.

• 터널과지하공간
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• 제14권4호
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• pp.261-268
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• 2004

The main objectives of this study are to investigate the anisotropic characteristics of rocks and to evaluate the relationships between physical properties. A series of experiments were performed in three mutually perpendicular directions for three rock types, which are granite, granitic gneiss and limestone. The relationships of measured physical properties were evaluated. The results of ultrasonic wave velocity measurement show that granite of three rock types gives the largest directional difference, and that the wave velocity in a plane parallel to a transversely isotropic one is dominantly faster than that in a subvertical or vertical plane. It implies that ultrasonic wave velocity for rock could be used as a useful tool for estimating the degree of anisotropy. The ratio of uniaxial compressive strength to Brazilian tensile strength ranges approximately from 13 to 16 for granite. from 8 to 9 for granite gneiss, and from 9 to 18 for limestone. The directional differences for granite and granitic gneiss are very small, and on the other hand, is relatively large for limestone. It is suggested that strength of rock makes quite difference depending on the rock types and loading directions, especially for the anisotropic rocks such as transversely isotropic or orthotropic rocks. The ratio of uniaxial compressive strength to point load strength index ranges from 18 to 20 for granite, from 17 to 19 for granitic gneiss, and from 21 to 24 for limestone. These results show that point load strength index makes also a difference depending on rock types and directions. Therefore. it should be noted that the ratio of uniaxial compressive strength to point load strength index could be applied to all rock types. Uniaxial compressive strength shows relatively good relationship with point load strength index, Schmidt hammer rebound value, and tensile strength. In particulat, point load strength index is shown to be the best comparative relationship. It is indicated that point load test is the most useful tool to estimate an uniaxial compressive strength indirectly.

• Journal of Welding and Joining
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• 제14권4호
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• pp.43-52
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• 1996

The plasma sprayed Cr$_{2}$C$_{2}$-NiCr coatings are widely used as wear-resistant and corrosion-resistant materials. The mechanical properties of the plasma sprayed Cr$_{2}$C$_{2}$-NiCr coatings were examined in this study. The distribution of the residual stress with the coating thickness was also examined by X-ray diffraction method. The pore in the coatings could be classified into two types ; one is the intrinsic pore originated from the spraying powder, the other is the extrinsic pore formed during spraying. During the tensile adhesion test, the fracture occurred at the interface of top coat and substrate or top coat and bond coat depending on the existence of bond coat. It was found that the compressive residual stress near the interface decreased with the increase of the top coat thickness. The tensile adhesion strength of the coating without bond coat was higher than that with bond coat, because the coating with bond coat has higher horizontal crack density near the interface between bond coat and top coat.

• 한국응용과학기술학회지
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• 제39권5호
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• pp.614-622
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• 2022

본 연구는 라벤더추출물을 첨가한 제형제를 제조하여 손상된 모발에 도포할 때 미치는 영향에 대하여 알아보고자 하였다. 실험재료는 라벤더추출물 함량을 0 g, 3 g, 6 g, 9 g 으로 펌베이스제에 첨가하여 제조하였다. 제조한 제형제로 4개의 손상 모발 시료에 도포하여 비교 분석하였다. 손상 모발에 미치는 영향에 대한 측정방법은 인장강도, 메틸렌블루를 이용한 흡광도, 광택을 측정하였다. 연구결과의 신뢰성을 위해 통계분석을 하였다. 인장강도 측정결과는 8레벨에 6 g 과 9 g 을 함유한 제형제로 도포 한 시료의 인장강도가 증가하여 손상모발에 영향을 미치는 것을 알 수 있었다. 메틸렌블루를 이용한 흡광도 분석 결과 추출물을 첨가하여 도포 한 모든 시료의 흡광도가 감소하여 손상모발에 영향을 미치는 것을 알 수 있었다. 광택 측정 결과는 9 g 첨가시에 손상모발에 영향을 미치는 것을 알 수 있었다. 결론은 라벤더추출물이 손상된 모발에 영향을 미치는 것을 알 수 있어 모질 개선효과가 있을 것으로 생각된다.

• 한국응용과학기술학회지
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• 제41권1호
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• pp.36-45
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• 2024

본 연구는 아보카도 오일을 첨가한 제형제를 제조하여 손상된 모발에 도포할 때 미치는 영향에 대하여 알아보고자 하였다. 실험재료는 아보카도 오일 함량을 0 g, 3 g, 6 g, 9 g 으로 펌베이스제에 첨가하여 제조하였다. 제조한 제형제로 4개의 손상 모발 시료에 도포하여 비교 분석하였다. 손상 모발에 미치는 영향에 대한 측정 방법은 인장강도, 메틸렌블루를 이용한 흡광도, 광택을 측정하였다. 연구 결과의 신뢰성을 위해 통계분석을 하였다. 인장강도 측정 결과는 시료에 6 g 과 9 g 을 함유한 제형제로 도포 한 시료의 인장강도가 증가하여 손상모발에 영향을 미치는 것을 알 수 있었다. 메틸렌블루를 이용한 흡광도 분석 결과 오일을 첨가하여 도포 한 모든 시료의 흡광도가 감소하여 손상모발에 영향을 미치는 것을 알 수 있었다. 광택 측정 결과는 6 g 과 9 g 첨가 시에 손상모발에 영향을 미치는 것을 알 수 있었다. 결론은 아보카도 오일이 손상된 모발에 영향을 미치는 것을 알 수 있어 모질 개선효과가 있을 것으로 생각된다.

• 통합자연과학논문집
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• 제6권1호
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• pp.1-7
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• 2013

Polyurethane resin containing isocyanate is marked by excellent tensile and mechanical strengths and this test aims to gauge its applicability as a medical high polymer. Tris [2-(acryloyloxy)ethyl]isocyanurate and hexamethylenediisocyanate were added to a basic mixing ratio of HEMA (2-hydroxyethyl methacrylate), MMA (methyl methacrylate), NVP (n-vinyl-2-pyrrolidone) and crosslink agent, EGDMA (ethylene glycol dimethacrylate) with increasing proportions and copolymerized respectively. Also, the basic physical properties of the polymerized high polymers including refraction rate, tensile strength, light transmission and water content were measured to confirm that they are appropriate as hydrogelcontact lenses. After measuring the physical properties of high performance polymers produced by adding tris [2-(acryloyloxy) ethyl]isocyanurate, it was found that the average tensile strengths of sample TRIS1 to TRIS10 were between 0.285 and 0.612 kgf, while the average values of refractive index were ranged from 1.441 to 1.449 with water content from 30.00 to 37.35%.The measurement of physical properties of the copolymers generated by adding hexamethylenediisocyanate showed that the average tensile strength of sample HEXA1 to HEXA10 ranged from 0.267 to 1.742 kgf, the refractive index ranged from 1.443 to 1.475 and water contents were in the range of 21.22 to 35.58%. In all combinations the transmission rates satisfied the transmittance of general hydrogel contact lenses. From theresults, it is possible to conclude that the produced copolymers can be used as contact lens materials with excellent tensile strength.

• 대한기계학회논문집
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• 제19권6호
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• pp.1479-1489
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• 1995

In this study, tensile strength and modulus were evaluated for a filament wound ring specimen by split disk test and compared with the theoretical values obtained by the rule of mixtures. The circumferentially wound ring specimens were prepared from 4 types of material systems. The results showed that the measured strengths of the composite systems were considerably lower than the theoretical values due to the local bending stresses around the split disk edges. for the measurement of elastic moduli of the filament wound ring specimens, the effect of friction on the strain of the ring must be taken into account. But the effect of friction between the split disk fixture and the ring specimen can be eliminated by averaging the moduli for loading and unloading state with maintaining the same crosshead rates. The measured elastic moduli of ring specimens showed very good agreement with the theoretical values.