• 지질공학
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• 제13권3호
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• pp.335-344
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• 2003

본 연구에서는 전라남도 장성과 화순에 분포하는 석회암풍화토의 물성 및 전단 특성을 연구하였다. 석회암풍화토의 교란시료에 대한 물성 및 전단 특성을 파악하기 위하여 실내 시험이 수행되었다. 연구지역의 석회암풍화토에 대한 물성 및 전단 특성은 다음과 같다 비중(Gs)은 2.78~2.80, 액성한계(LL)는 37~38(%), 소성지수(PI)는 13.7~15.4이며 흙의 분류(USCS)는 CL에 해당된다. 불포화 시료의 직접전단시험 (vd, $1.5t/\textrm{m}^3$)에 의한 강도정수는 점착력(c)이 3.07~4.4 ($t/\textrm{m}^2$) 그리고 내부마찰각($\Phi$)은 $34.8~42.4^{\circ}$의 범위를 보인다. 화강암풍화토 (양, 1997; 문. 1998; 박, 1998)와 비교해 보면, 연구지역의 석회암 풍화토의 물리적 특성은 일반적으로 차이를 보이며, 전단 강도정수 중, 내부마찰각은 대체적으로 유사한 경향을 보이는 것으로 나타났다.

• Restorative Dentistry and Endodontics
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• 제34권3호
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• pp.184-191
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• 2009

본 연구의 목적은 치면 처리와 수복물 내면의 처리가 필요 없는 자가 접착 레진 시멘트의 물성 및 lithium disilicate ceramic과 상아질에 대한 전단결합강도를 측정하고 기존의 레진 시멘트와 비교하여 임상적 유용성을 알아보고자 하는 것이다. 실험군인 자가 접착 레진 시멘트로는 Rely-X Unicem, Embrace Wetbond, Maxcem, BisCem을, 대조군으로는 기존의 레진 시멘트인 Rely-X ARC, 수복용 복합레진인 Z-350을 사용하였다. 각 레진 시멘트의 물성 평가를 위하여 테플론 주형을 이용하여 시편을 제작하고 만능 시험기를 이용하여 압축강도, 간접인장강도, 굴곡강도를 측정하였다. IPS Empress 2 및 상아질 시편에 제조사의 지시대로 Rely-X ARE군과 Z-350군에만 전처리를 시행 후 각 시멘트를 접착하고 전단결합강도를 측정하였다. 실험 결과는 다음과 같았다. 1. 자가 접착 레진 시멘트인 Biscem이 가장 낮은 물리적 성질을 나타내었다 (P<0.05). 2. 자가 접착 레진 시멘트의 상아질 및 도재에 대한 전단결합강도는 기존의 레진 시멘트에 비해 유의성 있게 낮은 값을 나타내었다. (P<0.05). 이상의 결과로 볼 때 자가 접착 레진 시멘트는 기존의 레진 시멘트에 비해 물리적 성질 및 상아질과 lithium disilicate ceramic에 대한 전단결합강도가 떨어지는 것으로 사료된다.

• 구강회복응용과학지
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• 제25권4호
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• pp.437-444
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• 2009

본 연구에서는 여러 automixing 레진시멘트의 물성과 상아질에 대한 전단결합강도를 평가, 비교하고자 하였다. Self-adhesive automixing 레진시멘트인 Rely-X Unicem(3M ESPE, St. Paul, USA), Embrace resin cement(Pulpdent, Oakland, USA)와 chemical polymerizing automixing 레진시멘트인 Resiment Ready-Mix(J.L.Blosser Inc., Liberty Missouri, USA)를 사용하였다. 물성을 평가하기 위하여 레진시멘트를 테프론 주형에 주입한 후 자가중합을 시키고 24시간 동안 빛이 차단된 상태로 100% 상대습도에 보관 후 만능 시험기를 이용하여 압축강도, 간접인장강도, 굴곡강도를 측정하였다. 상아질에 대한 전단결합강도를 평가하기 위하여 발거한 하악 제3대구치의 협측 상아질을 노출 시킨 후 일정한 크기로 레진시멘트를 부착시킨 뒤 만능 시험기를 이용하여 전단결합강도를 측정하였다. SPSS Ver 12.0(SPSS Inc., Chicago, IL, USA)을 사용하여 95% 유의수준에서 One way ANOVA test로 분석하였으며 Scheffe test로 사후검정 하였다. 연구결과, chemical polymerizing automixing 레진시멘트가 self-adhesive automixing 레진시멘트에 비해 상대적으로 높은 물리적 성질과 상아질에 대한 전단결합강도를 보였다.

• Geomechanics and Engineering
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• 제14권1호
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• pp.99-105
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• 2018

Soils are generally classified as fine-grained or coarse-grained depending on the percentage content of the primary constituents. In reality, soils are actually made up of mixed and composite constituents. Soils primarily classified as fine-grained, still consists of a range of coarse particles as secondary constituents in between 0% to 50%. A laboratory scale model test was conducted to investigate the influence of coarse particles on the physical (e.g., density, water content, and void ratio) and mechanical (e.g., quick undrained shear strength) properties of primarily classified fine-grained cohesive soils. Pure kaolinite clay and sand-mixed kaolinite soil (e.g., sand content: 10%, 20%, and 30%) having various water contents (60%, 65%, and 70%) were preconsolidated at different stress levels (0, 13, 17.5, 22 kPa). The quick undrained shear strength properties were determined using the conventional Static Cone Penetration Test (SCPT) method and the new Fall Cone Test (FCT) method. The corresponding void ratios and densities with respect to the quick undrained shear strength were also observed. Correlations of the physical properties and quick undrained shear strengths derived from the SCPT and FCT were also established. Comparison of results showed a significant relationship between the two methods. From the results of FCT and SCPT, there is a decreasing trend of quick undrained shear strength, strength increase ratio ($S_u/P_o$), and void ratio (e) as the sand content is increased. The quick undrained shear strength generally decreases with increased water content. For the same water content, increasing the sand content resulted to a decrease in quick undrained shear strength due to reduced adhesion, and also, resulted to an increase in density. Similarly, it is observed that the change in density is distinctively noticeable at sand content greater than 20%. However, for sand content lower than 10%, there is minimal change in density with respect to water content. In general, the results showed a decrease in quick undrained shear strength for soils with higher amounts of sand content. Therefore, as the soil adhesion is reduced, the cone penetration resistances of the FCT and SCPT reflects internal friction and density of sand in the total shear strength.

• Journal of the Korean Wood Science and Technology
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• 제39권5호
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• pp.429-436
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• 2011

The selected physical and mechanical properties of non-certificated LVL circulated in domestic lumber market were investigated and compared to relevant standards. The tested LVL passed the moisture content and the soaking delamination rate limit as per domestic (KS) and Japanese standard (JAS). The evaluated mechanical properties were flatwise/edgewise bending strength, modulus of elasticity (MOE), horizontal shear and compressive strength. The 30 mm-thick LVL showed significantly higher bending strength than that of the 25 mm-thick LVL. The modulus of elasticity (MOE) showed same tendency in the results of bending strength. The edgewise bending strength and MOE were higher than that of flatwise bending strength and MOE. The horizontal shear strength values were also showed similar results to bending strength values. The tested results were compared each other and each products were graded according to JAS 701 grade specification. The failure mode of LVL in bending test showed the similar failure mode of solidwood that failed in a simple tension manner (splintery tension). The glue line failure was severe in 25 mm-thick specimens due to concentration of shear stress in layer discontinuity containing small voids and starved glue lines. In horizontal shear strength test, failure mode of LVL showed the typical horizontal shear failure. Compressive specimens failed with fiber crushing in company with apparent delamination that splitted along the length of the specimens. From the results, the complete bonding between lamination and consistency in thin veneer layer were considered as a critical factor in the mechanical properties of LVL. Moreover, the standard test procedure and specification for non-certificated LVL should be required to check the performance of uncertificated materials.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.168-170
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• 2007

Sn-Bi eutectic solder alloy have is good wetting and physical properties. The results of solder paste properties test, melting point is about $139^{\circ}C$ and spread test is represent spread properties of $7{\sim}16%$. The results of shear strength after as reflowed, thermal shock test, high temperature storage test of 500hr and 1000hr at $100^{\circ}C$. The shear strength value range is from 6000 to 11000gf, pull strength value range is from 2200 to 3300gf.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
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• pp.85-90
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• 2006

Increasing the filler content of sheet improves the optical properties and printability of paper and provides an opportunity for saving production cost through fiber replacement with relatively low-priced filler. But increasing the filler content tends to decrease the strength of paper and filler retention. It also tends to deteriorate drainage on the paper machine. To overcome these problems, preflocculation technology of fillers may be employed. Many research efforts have been made on the properties of preflocculated filler, namely prefloc, whose size and size distribution were influenced by polymer type and shear level. But there is much to be investigated about the effect of the prefloc characteristics on the physical properties of paper. To evaluate the effect cationic polymers on the size and size distribution of preflocculated GCC and their shear stability, cationic PAM and cationic starch were used. The influence of the preflocculation on filler retention and its surface distribution, and the changes of physical and optical properties of handsheets affected by the characteristics of preflocs were examined. Filler distribution on sheet surface was also analyzed by EPMA. Results showed that cationic PAM formed large preflocs at low dosage. Cationic starch was required to add 15 times as much as cationic PAM to obtain the preflocs with similar size. But preflocs formed with cationic starch was superior in shear stability to those formed with cationic PAM. Filler preflocculation technology could provide an opportunity of increasing filler content significantly without loss in tensile strength. And increased filler contents could compensate brightness loss which often accompanies filler preflocculation. When excessively large preflocs were used, however, brightness loss rather than the improvement in tensile strength was predominant. Therefore it is of great importance to produce preflocs with proper size and shear stability for maximizing the improvement of physical properties of papers.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.723-728
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• 1997

The aim of this study is to define the physical properties of successive pours surfaces of concrete by various surface treatment methods with the laps of time. This paper is intended to study on the physical properties (the compressive strength, the tensile strength, the shear bonding strength and the bending strength) of the concrete successive pours surface used concrete surface finishing agent.

• Geomechanics and Engineering
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• 제17권1호
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• pp.31-45
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• 2019

In this study the spatial variability of soils is substantiated physically and numerically by using random field theory. Heterogeneous samples are fabricated by combining nine homogeneous soil clusters that are assumed to be elements of an adopted random field. Homogeneous soils are prepared by mixing different percentages of kaolin and bentonite at water contents equivalent to their respective liquid limits. Comprehensive characteristic laboratory tests were carried out before embarking on direct shear experiments to deduce the basic correlations and properties of nine homogeneous soil clusters that serve to reconstitute the heterogeneous samples. The tests consist of Atterberg limits, and Oedometric and unconfined compression tests. The undrained shear strength of nine soil clusters were measured by the unconfined compression test data, and then correlations were made between the water content and the strength and stiffness of soil samples with different consistency limits. The direct shear strength of heterogeneous samples of different stochastic properties was then evaluated by physical and numerical modelling using FISH code programming in finite difference software of $FLAC^{3D}$. The results of the experimental and stochastic numerical analyses were then compared. The deviation of numerical simulations from direct shear load-displacement profiles taken from different sources were discussed, potential sources of error was introduced and elaborated. This study was primarily to explain the mathematical and physical procedures of sample preparation in stochastic soil mechanics. It can be extended to different problems and applications in geotechnical engineering discipline to take in to account the variability of strength and deformation parameters.

• Restorative Dentistry and Endodontics
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• 제20권1호
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• pp.142-151
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• 1995

The purpose of this study was to compare and estimate the physical properties of five root canal sealers classified Calciobiotic root canals sealer as calcium hydroxide based sealer, Apatite root sealer type II as calcium phosphate based sealer, AH-26 as resin based sealer, Canals and Pulpdent root canals sealer as zinc oxide eugenol based sealer. The author investigated dimensional change and flow rate of canal sealers, diametral tensile strength and shear bond strength of sealers to dentin to evaluate the physical properties on affect of complete obturation of root canal and performed the total 100 specimens of each 25 sealers under the condition of root temperature according to manufacturer's instructions. All specimens were stored at $37{\pm}1^{\circ}C$ in 100 % relative humidity. A microscope for measurement of micro distance is used for the dimensional change test and evacuation methods using vaccum were used for the flow rate test. The result differed by the storage time measured on the tests of diametral tensile strength and shear bond strength to dentin. The following results were obtained ; 1 On the test of dimensional change, Canals and Pulpdent expanded slightly, AH-26 and Apatite showed the severe shrinkage after 48 hours. 2. AH-26 and Apatite were the excellent with each 24.59mm, 31.19mm after 3 minutes in the aspect of flow property. 3. On the diametral tensile strength, Calciobiotic root canals sealer showed the highest strength with 27.13kg/$cm^2$ after 48 hours, Apatite root sealer type II showed highest strength with 84.57kg/$cm^2$ after 120 hours. 4. On the shear bond strength to dentin, AH-26 was most excellent with 55.73kgf/$cm^2$ after 24 hours and with 134.71kgf/$cm^2$ after 120 hours.