• Title/Summary/Keyword: remaining strength

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Changes in Photosynthesis and Carbohydrate Reserves of 'Fuji'/M9 Apple trees in Response to Early Defoliation at Growing Period (생육기 조기낙엽에 따른 사과 '후지'/M9의 광합성과 탄수화물의 변화)

  • Jeong, Jae Hoon;Han, Jeom Hwa;Ryu, Suhyun;Han, Hyun Hee;Kwon, YongHee;Do, Gyung-Ran;Yim, Sun-Hee;Lee, Han-Chan
    • Journal of Bio-Environment Control
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    • v.26 no.4
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    • pp.291-296
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    • 2017
  • This study was conducted to evaluate the influence of early defoliation on photosynthesis and carbohydrate reserves when the source leaves of 'Fuji'/M9 apple (Malus domestica Borkh.) trees were removed during the growing period. Bud regrowth rates of 80%, 50% defoliation and non-defoliation treatments were significantly different 82.7%, 45.9% and 2.1% respectively at 30 days after treatment. In all treatments, sucrose and starch concentrations in remaining leaves decreased non-significantly during the 14-day period. No significant changes were observed for total soluble carbohydrates in non-defoliation and 50% defoliation. However, in 80% defoliated treatments, concentrations of sorbitol and total soluble carbohydrates in remaining leaves declined steadily during the 14-day period. It is thought that high sink strength increases the requirements of carbohydrate from remaining leaves more than non-defoliated. The concentrations of starch in the roots tend to decrease non-significantly as percentage of defoliation increased. Photosynthesis of remaining leaves was monitored during the 14-day period after partial defoliation treatments. Net photosynthetic rates (Pn) and stomatal conductance were significantly enhanced in the 80% defoliation. The observed photosynthetic enhancement following partial defoliation may have been due to the enhancement of osmotic potential in leaves. These results were estimated that increasing of photosynthetic rate in the partial defoliation is due to the sink carbohydrate requirements for the current year's secondary growth of buds.

COMPARISON OF MECHANICAL PROPERTIES OF VARIOUS POST AND CORE MATERIALS

  • Ahn Seung-Geun;Sorensen John A.
    • The Journal of Korean Academy of Prosthodontics
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    • v.41 no.3
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    • pp.288-299
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    • 2003
  • Statement of problem: Many kinds of post and core systems are in the market, but there are no clear selection criteria for them. Purpose: The purpose of this study was to compare the flexural strength and modulus of elasticity of core materials, and measure the bending strength of post systems made of a variety of materials. Material and Methods: The flexural strength and elastic modulus of thirteen kinds core buildup materials were measured on beams of specimens of 2.0×2.0×24±0.1mm2.0×2.0×24±0.1mm. Ten specimens per group were fabricated and loaded on an lnstron testing machine at a crosshead speed of 0.25mm/min. A test span of 20 mm was used. The failure loads were recorded and flexural strength calculated with the measured dimensions. The elastic modulus was calculated from the slopes of the linear portions of the stress-stram graphs. Also nine kinds commercially available prefabricated posts made of various materials with similar nominal diameters, approximately 1.25mm, were loaded in a three-point bend test until plastic deformation or failure occurred. Ten posts per group were tested and the obtained data were anaylzed with analysis of variance and compared with the Tukey multiple comparison tests. Results: Clearfil Photo Core and Luxacore had flexural strengths approaching amalgam, but its modulus of elasticity was only about 15% of that of amalgam. The strengths of the glass ionomer and resin modified glass ionomer were very low. The heat pressed glass ceramic core had a high elastic modulus but a relatively low flexural strength approximating that of the lower strength composite resin core materials. The stainless steel, zirconia and carbon fiber post exhibited high bending strengths. The glass fiber posts displayed strengths that were approximately half of the higher strength posts. Conclusion: When moderate amounts of coronal tooth structure are to be replaced by a post and core on an anterior tooth, a prefabricated post and high strength, high elastic modulus core may be suitable. CLINICAL IMPLICATIONS In this study several newly introduced post and core systems demonstrated satisfactory physical properties. However when the higher stress situation exists with only a minimal ferrule extension remaining a cast post and core or zirconia post and pressed core are desirable.

Effects of a new desensitizing paste containing 8% arginine and calcium carbonate on the shear bond strength of orthodontic brackets

  • Yagci, Ahmet;Uysal, Tancan;Akinci, Hatice;Uysal, Banu
    • The korean journal of orthodontics
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    • v.41 no.2
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    • pp.121-126
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    • 2011
  • Objective: The purpose of this study was to evaluate shear bond strength (SBS) and failure site location of brackets bonded to enamel with or without desensitizer application. Methods: Sixty-six freshly extracted human premolar teeth were randomly divided into 3 groups of 22. Group 1 served as the control. Desensitizer was applied to the remaining teeth at two time intervals (Group 2, bonded immediately after Pro-ReliefTMReliefTM (Colgate-Palmolive Co., New York, NY, USA) application and Group 3, bonded 30 days after Pro-ReliefTMReliefTM application with the teeth stored in artificial saliva during the 30 days). Orthodontic brackets were bonded with a light cure composite resin and cured with a halogen light. After bonding, the SBS of the brackets was tested using a universal testing device. Adhesive remnant index (ARI) scores were determined after the brackets failed. Data were analyzed with analysis of variance, Tukey's HSD, and G tests. Results: The SBS was significantly lower in Group 2 than in Groups 1 (p = 0.024) and 3 (p = 0.017). Groups 1 and Group 3 did not differ (p = 0.991). ARI scores did not differ significantly among groups. Conclusions: The Pro-ReliefTMReliefTM desensitizer agent applied immediately before bonding significantly reduces bond strength, but the SBS values still exceed the minimum 5.9 - 7.8 MPa required for adequate clinical performance. Immersing the teeth in artificial saliva for 30 days after applying the Pro-ReliefTMReliefTM desensitizer agent and before bonding increased the SBS to control levels.

Fatigue Strength in Aged Turbine Rotor Steel (시효 열화시킨 터빈 로터강의 피로강도에 관한 연구)

  • 서창민;허정훈;이해무;서덕영
    • Journal of Ocean Engineering and Technology
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    • v.10 no.2
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    • pp.77-87
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    • 1996
  • The estimation of the remaining life for the aged components in power plant as well as chemical and peroleum plants has been recently coberned. The raw materials used in this syudy are the 1Cr-1Mo-0.25V rotor steel which intensified P and S compositions along with the nominal compositions of ASTM A470 standard. Five kinds of specimens with the different degradation levels were prepared by isothermal aging teat treatment at 630C630C The mechanical properties and fatigue strength of virgin and aged 1Cr-1Mo-0.25V rotor steel have been inbestigated through the hardness, tensile, fatigue test, SEM fractograph and EDS analysis at room temperature. Thus, the data of aged specimens were compared with those of virgin specimen to evaluate the aging effects. The main results obtained in this study are as follows; The decrease of the hardness due to degradation was distinguished until 50, 000hrs simulated service time. And is was confirmed that the considerable amount of P, Mn, Cr and S was precipitated at the grain boundary of aged material through the SEM and EDS analysis. The fatigue strength of 25, 000, 50, 000, 75, 000 and 100, 000hrs aged material was decreased 29.5%, 24.4%, 28.6%, 35.7% than that of virgin material at 107107 cycles of room temperature. The major cracks of virgin and aged materials initiated at the inclusions including Si, P and Mn compositions which were located at the outer periphery of the specimen.

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FracSys와 UDEC을 이용한 사면 파괴 양상 분석 통계적 절리망 생성 기법 및 Monte Carlo Simulation을 통한 사면 안정성 해석

  • 김태희;최재원;윤운상;김춘식
    • Proceedings of the Korean Geotechical Society Conference
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    • 2002.03a
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    • pp.651-656
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    • 2002
  • In general, the most important problem in slope stability analysis is that there is no definite way to describe the natural three-dimensional Joint network. Therefore, the many approaches were tried to anlayze the slope stability. Numerical modeling approach is one of the branch to resolve the complexity of natural system. UDEC, FLAC, and SWEDGE are widely used commercial code for the purpose on stability analysis. For the purpose on the more appropriate application of these kind of code, however, three-dimensional distribution of joint network must be identified in more explicit way. Remaining problem is to definitely describe the three dimensional network of joint and bedding, but it is almost impossible in practical sense. Three dimensional joint generation method with random number generation and the results of generation to UDEC have been applied to settle the refered problems in field site. However, this approach also has a important problem, and it is that joint network is generated only once. This problem lead to the limitation on the application to field case, in practical sense. To get rid of this limitation, Monte Carlo Simulation is proposed in this study 1) statistical analysis of input values and definition of the applied system with statistical parameter, 2) instead of the consideration of generated network as a real system, generated system is just taken as one reliable system, 3) present the design parameters, through the statistical analysis of ouput values Results of this study are not only the probability of failure, but also area of failure block, shear strength, normal strength and failure pattern, and all of these results are described in statistical parameters. The results of this study, shear strength, failure area, pattern etc, can provide the direct basement on the design, cutoff angle, support pattern, support strength and etc.

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Effect of dentin biomodifiers on the immediate and long-term bond strengths of a simplified etch and rinse adhesive to dentin

  • Singh, Payal;Nagpal, Rajni;Singh, Udai Pratap
    • Restorative Dentistry and Endodontics
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    • v.42 no.3
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    • pp.188-199
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    • 2017
  • Objectives: This in vitro study evaluated the effect of dentin biomodifiers on the immediate and long-term bond strengths of a simplified etch and rinse adhesive to dentin. Materials and Methods: Flat coronal dentin surfaces were prepared in 120 extracted human molars. Teeth were randomly divided into 5 groups (n = 24) according to 5 different surface pre-treatments: No pre-treatment (control); 1M carbodiimide (EDC); 0.1% epigallocatechin-3-gallate (EGCG); 2% minocycline (MI); 10% sodium ascorbate (SA). After surface pre-treatment, adhesive (Adper Single Bond 2 [SB], 3M ESPE) was applied. Composite was applied into transparent plastic tubes (2.5 mm in diameter), which was placed over the bonded dentin surface. From each group, 10 samples were subjected to shear bond strength (SBS) evaluation at 24 hours (immediate) and remaining 10 samples were tested after 6 months (delayed). Additionally, 4 samples per group were subjected to scanning electron microscopic analysis for observation of resin-dentin interface. The data were statistically analysed with Shaperio-Wilk W test, 2-way analysis of variance (ANOVA), and post hoc Tukey's test. Results: At 24 hours, SBS of all surface pre-treatment groups were comparable with the control group, with significant differences found between EDC and SA groups only (p = 0.009). After 6 months storage, EDC, EGCG, and MI pre-treatments preserved the resindentin bond strength with no significant fall. Conclusions: Dentin pre-treatment with all the dentin biomodifiers except SA resulted in significant preservation of resin-dentin bond over 6 months storage period, without negatively affecting the immediate bond strength of the etch and rinse adhesive tested.

TENSILE STREGNTH BETWEEN MACHINABLE CERAMIC AND DENTIN CEMENTED WITH LUTING COMPOSITE RESIN CEMENTS (합착용 복합레진시멘트로 합착한 Machinable Ceramic과 상아질 사이의 인장강도에 대한 실험적 연구)

  • Cho, Byeong-Hoon
    • Restorative Dentistry and Endodontics
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    • v.23 no.1
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    • pp.487-501
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    • 1998
  • In the case of CAD/CAM ceramic inlay restorations, if isthmus width is widened too much, it may cause fracture of remaining tooth structure or loss of bonding at the luting interface because of excessive displacement of buccal or lingual cusps under occlusal loads. So to clarify the criterior of widening isthmus width, this study was designed to test the tensile bond strength and bond failure mode between dentin and ceramic cemented with luting composite resin cements. Cylindrical ceramic blocks(Vita Cerec Mark II, d=4mm) were bonded to buccal dentin of 40 freshly extracted third molars with 4 luting composite resin cements(group1 : Scotchbond Resin Cement/Scotchbond Multi-Purpose, group2 : Duolink Resin Cement/ All-Bond 2, group3: Bistite Resin Cement/Ceramics Primer, and group4:Superbond C&B). Tensile bond test was done under universal testing machine using bonding and measuring alignment blocks(ϕiloϕilo & Urn, 1992). After immersion of fractured samples into 1 % methylene blue for 24 hours, failure mode was analysed under stereomicroscope and SEM. Results: The tensile bond strength of goup 1, 2 & 4 was 13.97±2.9013.97±2.90 MPa, 16.49±3.9016.49±3.90 MPa and 16.l7±4.3216.l7±4.32 MPa, respectively. There was no statistical differences(p>0.05). But, group 3 showed significantly lower bond stregnth(5.98±1.l75.98±1.l7 MPa, p<0.05). In almost all samples, adhesive fractures between dentin and resin cements were observed. But, in group 1, 2 & 4, as bond strength increased, cohesive fracture within resin cement was observed simultaneously. And, in group 3, as bond strength decreased, cohesive fracture between hybrid layer and composite resin cement was also observed. Cohesive fracture within dentin and porcelain adhesive fracture were not observed. In conclusion, although adhesive cements were used in CAD/CAM -fabricated ceramic inlay restorations, the conservative priciples of cavity preparation must be obligated.

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Strength prediction of corrosion reinforced concrete columns strengthened with concrete filled steel tube under axial compression

  • Liang, Hongjun;Jiang, Yanju;Lu, Yiyan;Hu, Jiyue
    • Steel and Composite Structures
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    • v.37 no.4
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    • pp.481-492
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    • 2020
  • Twenty-two corrosion-damaged columns were simulated through accelerated steel corrosion tests. Eight specimens were directly tested to failure under axial load, and the remaining specimens were tested after concrete-filled steel tube (CFST) strengthening. This study aimed to investigate the damage of RC columns after corrosion and their restoration and enhancement after strengthening. The research parameters included different corrosion degrees of RC columns, diameter-to-thickness ratio of steel tube and the strengthening concrete strength. Experimental results showed that CFST strengthening method could change the failure mode of corrosion-damaged RC columns from brittleness to ductility. In addition to the bearing capacity provided by the strengthening materials, it can also provide an extra 26.7% amplification because of the effective confinement provided by steel tubes. The influence of corrosion on reinforcement and concrete was quantitatively analysed and considered in the design formula. The proposed formula accurately predicted the bearing capacity of the strengthened columns with a maximum error of only 7.68%.

Sensor Location Estimation in of Landscape Plants Cultivating System (LPCS) Based on Wireless Sensor Networks with IoT

  • Kang, Tae-Sun;Lee, Sang-Hyun
    • International Journal of Internet, Broadcasting and Communication
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    • v.12 no.4
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    • pp.226-231
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    • 2020
  • In order to maximize the production of landscape plants in optimal condition while coexisting with the environment in terms of precision agriculture, quick and accurate information gathering of the internal environmental elements of the growing container is necessary. This may depend on the accuracy of the positioning of numerous sensors connected to landscape plants cultivating system (LPCS) in containers. Thus, this paper presents a method for estimating the location of the sensors related to cultivation environment connected to LPCS by measuring the received signal strength (RSS) or time of arrival TOA received between oneself and adjacent sensors. The Small sensors connected to the LPCS of container are known for their locations, but the remaining locations must be estimated. For this in the paper, Rao-Cramer limits and maximum likelihood estimators are derived from Gaussian models and lognormal models for TOA and RSS measurements, respectively. As a result, this study suggests that both RSS and TOA range measurements can produce estimates of the exact locations of the cultivation environment sensors within the wireless sensor network related to the LPCS.

Behavior of PCC During Loading at High Consistency Pulp Slurry (고농도 펄프 슬러리 충전에서 PCC의 거동)

  • Cho, Byoung-Uk;Won, Jong-Myoung
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.43 no.5
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    • pp.43-48
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    • 2011
  • Filler loading at thick stock was carried out in order to verify if the dual addition of filler can be used as a means to reduce the detrimental effects of filler on the strength properties of paper. PCC was added to 3.5% pulp slurry blended with HwBKP, BCTMP and SwBKP. Cationic starch was used as a fixing agent. The mixture of PCC and pulp was stirred for 5, 10 and 20min. at 1,000 rpm. The remaining PCC was washed out before handsheet making. PCC particles were flocculated and fixed on the pulp fiber and/or space between fibers. It is expected that the flocculation and inclusion of PCC can be helpful to improve the strength properties of paper due to the reduction of detrimental effect in fiber bonding. The distinct tendency in PCC flocculation and fixing on pulp fiber was not observed by the change of cationic starch dosage and treatment time.