• Title/Summary/Keyword: Length of penetration

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Growth and yield responses of rice varieties to various soil water deficit conditions under different soil types

  • Kikuta, Mayumi;Samejima, Hiroaki;Magoti, Rahab;Kimani, John M.;Yamauchi, Akira;Makihara, Daigo
    • Proceedings of the Korean Society of Crop Science Conference
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    • 2017.06a
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    • pp.322-322
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    • 2017
  • To avoid drought stress under rainfed upland conditions, it is important for rice to efficiently utilize water at shallow soil layers supplied by rainfall, and access to water retained in deer soil layers. The root developmental characteristics of rice, which play important role in the adaptability to drought conditions, vary depending on the variety. Moreover, water availability for plant differs depending on the soil types that have different physical properties such as water holding capacity, permeability, capillary force, penetration resistance, etc. In this study, we evaluated growth and yield responses of rice varieties to various soil water deficit conditions under three different soil types. The experiment was conducted in a plastic greenhouse at the Kenya Agricultural and Livestock Research Organization-Mwea from October 2016 to January 2017. Two upland varieties (NERICA 1 and 4) and one lowland variety (Komboka) were grown in handmade PVC pots (15.2 cm diameter and 85.0 cm height) filled with three different types of soil collected from major rice-growing areas of the country, namely black cotton (BC), red clay (RC), and sandy clay (SC). Three watering methods, 1) supplying water only from the soil surface (W1), 2) supplying water only from the bottom of the pots (W2), and 3) supplying water both from the soil surface and the bottom of pots (W3), were imposed from 40 days after sowing to maturity. Soil water content (SWC) at 20, 40, and 60 cm depths was measured regularly. At the harvesting stage, aboveground and root samples were collected to determine total dry weight (TDW), grain yield, and root length at 0-20, 20-40, 40-60, and 60-80 cm soil layers. Irrespective of the watering methods, the greatest root development was obtained in RC, while that in BC was less than other two soils. In BC, the degree of yield reduction under W1 was less than that in RC and SC, which could be attributed to the higher water holding capacity of BC. In RC, the growth and yield reduction observed in all varieties under W1 was attributed to the severe drought stress. On the other hand, under W2, SWC at the shallow soil depth in RC was maintained because of its higher capillary force compared with BC and SC. As the result, growths and yields in RC were not suppressed under W2. In SC, deep root development was not promoted by W2 irrespective of the varieties, which resulted in significant yield losses. Under W1, the rice growth and yield in SC was decreased although shallow root development was enhanced, and the stomatal conductance was maintained higher than RC. It was suspected that W1 caused nutrients leaching in SC because of its higher permeability. Under rainfed conditions, growth and yield of rice can be strongly affected by soil types because dynamics of soil water conditions change according to soil physical properties.

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MICROLEAKAGE OF RESILON BY METHACRYLATE-BASED SEALER AND SELF-ADHESIVE RESIN CEMENT (Resilon을 이용한 근관충전 시 레진계열의 근관실러와 자가-접착 레진시멘트에 따른 미세누출)

  • Ham, Sun-Young;Kim, Jin-Woo;Shin, Hye-Jin;Cho, Kyung-Mo;Park, Se-Hee
    • Proceedings of the KACD Conference
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    • 2008.05a
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    • pp.204-212
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    • 2008
  • The purpose of this study was to compare the apical microleakage in root canal filled with Resilon by methacrylate-based root canal sealer or 2 different self-adhesive resin cements. Seventy single-rooted extracted human teeth were sectioned at the CEJ perpendicular to the long axis of the roots with diamond disk. Canal preparation was performed with crown-down technique using Profile NiTi rotary instruments and GG drill. Each canal was prepared to ISO size 40, .04 taper and 1 mm short from the apex. The prepared roots were randomly divided into 4 experimental groups of 15 roots each and 5 roots each for positive and negative control group. The root canals were filled by lateral condensation as follows. Group 1: Gutta-percha with AH-26, Group 2: Resilon with RealSeal primer & sealer, Group 3: Resilon with Rely-X Unicem, Group 4: Resilon with BisCem. After stored in $37^{\circ}C$, 100% humidity chamber for 7 days, the roots were coated with 2 layers of nail varnish except apical 3 mm. The roots were then immersed in 1% methylene blue dye for 7 days. Apical microleakage was measured by a maximum length of linear dye penetration after roots were separated longitudinally. One way ANOVA and Scheffe's post-hoc test were performed for statistical analysis. Group 1 showed the least apical leakage and there was no statistical significance between Group 2, 3, 4. According to the results, the self adhesive resin cement is possible to use as sealer instead of primer & sealant when root canal filled by Resilon.

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Observation of Dendritic Spines of Purkinje Cell Using High-Voltage Electron Microscopy (고압전자현미경을 이용한 소뇌 조롱박세포 가지돌기가시 관찰)

  • Rhyu, Im-Joo;Lee, Kea-Joo;Suh, Young-Suk
    • Applied Microscopy
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    • v.31 no.1
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    • pp.1-8
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    • 2001
  • The morphological features of neuronal dendritic spines are changed their shapes, sizes and density in response to physiological or pathological conditions . Therefore, exact analysis of spines warrants understanding of neuronal function. The size of the spine is at the borderline of resolution with light microscopy. High voltage electron microscopy Provide excellent resolution of the spines with proper stain techniques thanks to its higher resolution and penetration power. We evaluated more effective staining method for observing dendritic spines after labeling Purkinje cells with anti-calbindin 28 kD immunohistochemistry or Golgi staining methods. 4 fm thickness sections were observed with high voltage electron microscopy and some morphometric analyses were performed. Both Golgi staining and immunohistochemistry revealed the detail structures of the Purkinje cell such as soma, dendrites, and dendritic spines. High voltage electron micrographs with Golgi staining provide more precise morphology and are easy to measure. Average density of spine is $24.5{\pm}3.6/10{\mu}m$ and its length is $1.12{\pm}0.22{\mu}m$. For quantitative analysis of the spines, high voltage electron, micrographs with Golgi staining are more effective. This preliminary result is expected to be useful for further study of spine plasticity in various conditions.

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The Effects of the Spat Planting Time and Environmental Factors in the Arkshell, Scapharca broughtonii Schrenck Culture (피조개(Scapharca broughtonii Schrenck) 양식시 살포시기와 환경 특성의 영향)

  • Kim, Jeong-Bae;Lee, Sang-Yong;Jung, Choon-Goo;Jung, Chang-Su;Son, Sang-Gyu
    • Journal of Aquaculture
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    • v.20 no.1
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    • pp.31-40
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    • 2007
  • To find out the effect of the spat planting time and environmental factors in the arkshell, Scapharca broughtonii (Schrenck), we investigated the growth, survival rate of arkshell and habitat characteristics in Gamak Bay, Yeoja Bay and Saryang Island. We planted artificial spats of arkshell in Gamak Bay and Yeoja Bay at November 2004, and also planted domestic and Chinese natural spats in Saryang Island at March 2005. We measured growth, survival rate of arkshell, physiochemical parameters of the water mass (water temperature, salinity, dissolved oxygen, nutrients and chlorophyll a) and characteristics of the sediment (oxygen penetration depth, oxygen microprofiles, ignition loss and chemical oxygen demand) by monthly. The cumulative survival ratio of arkshell in Gamak Bay was the highest at December, whereas the ratio of arkshell in Yeoja Bay was recorded as 0% at October. The monthly growth rates of arkshell length in Gamak Bay and Yeoja Bay were the highest in May and the growth rate of the Korean arkshell in Saryang Island was higher than Chinese ones significantly. The high mortality (> 65%) of the arkshell in Yeoja Bay during summer probably caused by high water temperature, inflow of low salinity water, and low dissolved oxygen concentration in sediment. The concentrations of nutrient and sediment COD were considered to play an important role in the monthly survival ratio of arkshell in Gamak Bay and Sarayng Island. We suggest that the growth and mortality of arkshell might be influenced to the planting time of spat and the habitat characteristics.

Study on Bearing Capacity of Ultra High Strengh End Extended PHC Pile by Loading Test (재하시험을 통한 초고강도 선단확장 PHC말뚝의 적용성 연구)

  • Hwang, Ui-Seong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.3
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    • pp.269-275
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    • 2019
  • As the national industry is developing gradually due to the expansion of the economic scale, the construction of large and super high-rise structures for building social infrastructure has been increasing, and studies have been conducted actively to transmit the large loads at the upper portion to the lower bedrock. In this study, the PHC was extended to an ultra-high strength PHC, which increased the concrete compressive strength of the PHC from the conventional 80 MPa to 110 MPa, and the PHC, which extended the tip of the pile. After construction with the driving method and injected pile method, the tendency of the bearing capacity was tested through a load test. Measurements of the bearing capacity of the extended PHC using the pile driving method revealed the main surface friction force to be smaller than that of the general PHC, and the stet-up effect was also insignificant. On the other hand, the effect of the friction force on the ground surface when the injected pile method was applied is expected to increase the bearing capacity when the gap between the main surface and the ground is wide and the cement paste is filled tightly. In addition, the ultrahigh strength PHC showed higher bearing capacity than the conventional PHC, and the permissible pile stress was less than 60%. Therefore, it is possible to reduce the number of piles and reduce the construction cost and effect of shortening the length of the pile by designing the tip of the pile on the ground with the intensity of soft rock as a method for utilizing the increased strength of the ultra-high strength PHC.

MICROLEAKAGE OF RESILON BY METHACRYLATE-BASED SEALER AND SELF-ADHESIVE RESIN CEMENT (Resilon을 이용한 근관충전 시 레진계열의 근관실러와 자가-접착 레진시멘트에 따른 미세누출)

  • Ham, Sun-Young;Kim, Jin-Woo;Shin, Hye-Jin;Cho, Kyung-Mo;Park, Se-Hee
    • Restorative Dentistry and Endodontics
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    • v.33 no.3
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    • pp.204-212
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    • 2008
  • The purpose of this study was to compare the apical microleakage in root canal filled with Resilon by methacrylate-based root canal sealer or 2 different self-adhesive resin cements. Seventy single-rooted extracted human teeth were sectioned at the CEJ perpendicular to the long axis of the roots with diamond disk. Canal preparation was performed with crown-down technique using Profile NiTi rotary instruments and GG drill. Each canal was prepared to ISO size 40, .04 taper and 1 mm short from the apex. The prepared roots were randomly divided into 4 experimental groups of 15 roots each and 5 roots each for positive and negative control group. The root canals were filled by lateral condensation as follows. Group 1: Guttapercha with AH-26, Group 2: Resilon with RealSeal primer & sealer, Group 3: Resilon with Rely-X Unicem, Group 4: Resilon with BisCem. After stored in $37{\circ}C$, 100% humidity chamber for 7 days, the roots were coated with 2 layers of nail varnish except apical 3 mm. The roots were then immersed in 1% methylene blue dye for 7 days. Apical microleakage was measured by a maximum length of linear dye penetration after roots were separated longitudinally. One way ANOVA and Scheffe's post-hoc test were performed for statistical analysis. Group 1 showed the least apical leakage and there was no statistical significance between Group 2, 3, 4. According to the results, the self adhesive resin cement is possible to use as sealer instead of primer & sealant when root canal filled by Resilon.

MICROLEAKAGE OF CURRENT DENTIN BONDING SYSTEMS (복합레진 수복시 복합용기 및 단일용기 상아질 접착제의 미세변연누출에 관한 연구)

  • Ryu, Ju-Hee;Park, Dong-Sung;Kwon, Hyuk-Choon
    • Restorative Dentistry and Endodontics
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    • v.24 no.1
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    • pp.55-66
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    • 1999
  • The purpose of this study was to evaluate the microleakage of 5 current dentin bonding systems which are composed of 2 multi-bottle systems(Scotchbond Multi-Purpose, All Bond2) and 3 one-bottle systems(Single bond, One-Step, Prime & Bond). In this in vitro study, class V cavities were prepared on buccal and lingual surfaces of sixty extracted human premolars and molars on cementum margin. The experimental teeth were randomly divided into six groups of 10 samples (20 surfaces) each, Group 1 : Scotchbond Multi-Purpose ; Group 2 : All Bond 2 ; Group 3 : Single Bond ; Group 4 : One-Step ; Group 5 : Prime & Bond ; Group 6 : no bonding agent(control). The bonding agent and composite resin were applied for each group following the manufacturer's instructions. After 500 thermocycling between $5^{\circ}C$ and $55^{\circ}C$, the 60 teeth were placed in 2% Methylene blue dye for 24 hours, then rinsed with tab water. The specimen were embedded in clear resin, then sectioned buccolingually through the center of restoration with a low speed diamond saw. The dye penetration on each of the specimen were then observed with a stereomicroscope at ${\times}20$. The results of study were statistically analyzed using the Student-Newmann-Keul's Methods and the Mann-Whitney Rank Sum Test. The resin/dentin interfaces were examined under Scanning Electron Microscopy. The results of this study were as follows. 1. None of the dentin bonding systems used in this study showed significant difference in leakage values at both the enamel and the dentin margins (P>0.05). 2. In all groups except the control, leakage value seen at the enamel margin was significantly lower than that seen at the dentin margin (P<0.05). 3. Compared to the control group, all the groups treated with dentin bonding systems showed significantly lower leakage value at both enamel and dentin margins (P<0.05). 4. In the SEM view, gaps were observed in the composite resin / dentin interface in group 6 where no dentin bonding agent was used, and in all the other groups (group 1, 2, 3, 4, 5) composite resin, hybrid layer, and dentin were seen to be closely adhering to each other where there were no leakages. Well-developed resin tags 3~100${\mu}m$ in length infiltrated dentinal tubules past the hybrid layer and a hybrid layer 1~5${\mu}m$ thick had developed between the dentinal surface and the composite resin surface.

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An Experimental Study on the Effect of Capillary Pressure on the Void Formation in Resin Transfer Molding Process (수지이동 성형공정에서 기공형성에 미치는 모세관압의 영향에 관한 실험적 연구)

  • 이종훈;김세훈;김성우;이기준
    • The Korean Journal of Rheology
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    • v.10 no.4
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    • pp.185-194
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    • 1998
  • Flow-induced voids during resin impregnation and poor fiber wetting give serious effects on the mechanical properties of composites in resin transfer molding process. In order to better understand the characteristics of resin flow and to investigate the mechanism of void formation, flow visualization experiment for the resin impregnation was carried out on plain weaving glass fiber mats using silicon oils with various viscosity values. The permeability and the capillary pressure for the fiber mats of different porosities were obtained by measuring the penetration length of the resin with time and with various injection pressure. At low porosity and low operating pressure, the capillary pressure played a significant role in impregnation process. Video-assisted microscopy was used in taking the magnified photograph of the flow front of the resin to investigate the effect of the capillary pressure on the void formation. The results showed that the voids were formed easily when the capillary pressure was relatively high. No voids were detected above the critical capillary number of 2.75$\times$$10^{-3}, and below the critical number the void content increased exponentially with decrease of the capillary number. The content of void formed was independent of the viscosity of the resin. For a given capillary number, the void content reduced with the lower porosity of the fiber mat.

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Biomechanical Comparison of Inter-fragmentary Compression Pressures : Lag Screw versus Herbert Screw for Anterior Odontoid Screw Fixation

  • Park, Jin-Woo;Kim, Kyoung-Tae;Sung, Joo-Kyung;Park, Seong-Hyun;Seong, Ki-Woong;Cho, Dae-Chul
    • Journal of Korean Neurosurgical Society
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    • v.60 no.5
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    • pp.498-503
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    • 2017
  • Objective : The purpose of the present study was to compare inter-fragmentary compression pressures after fixation of a simulated type II odontoid fracture with the headless compression Herbert screw and a half threaded cannulated lag screw. Methods : We compared inter-fragmentary compression pressures between 40- and 45-mm long 4.5-mm Herbert screws (n=8 and n=9, respectively) and 40- and 45-mm long 4.0-mm cannulated lag screws (n=7 and n=10, respectively) after insertion into rigid polyurethane foam test blocks (Sawbones, Vashon, WA, USA). A washer load cell was placed between the two segments of test blocks to measure the compression force. Because the total length of each foam block was 42 mm, the 40-mm screws were embedded in the cancellous foam, while the 45-mm screws penetrated the denser cortical foam at the bottom. This enabled us to compare inter-fragmentary compression pressures as they are affected by the penetration of the apical dens tip by the screws. Results : The mean compression pressures of the 40- and 45-mm long cannulated lag screws were $50.48{\pm}1.20N$ and $53.88{\pm}1.02N$, respectively, which was not statistically significant (p=0.0551). The mean compression pressures of the 40-mm long Herbert screw was $52.82{\pm}2.17N$, and was not statistically significant compared with the 40-mm long cannulated lag screw (p=0.3679). However, 45-mm Herbert screw had significantly higher mean compression pressure ($60.68{\pm}2.03N$) than both the 45-mm cannulated lag screw and the 40-mm Herbert screw (p=0.0049 and p=0.0246, respectively). Conclusion : Our results showed that inter-fragmentary compression pressures of the Herbert screw were significantly increased when the screw tip penetrated the opposite dens cortical foam. This can support the generally recommended surgical technique that, in order to facilitate maximal reduction of the fracture gap using anterior odontoid screws, it is essential to penetrate the apical dens tip with the screw.

Strength and Durability Characteristics of Low-alkali Mortar for Artificial Reefs Produced by 3D Printers (인공어초 3D 프린터 출력을 위한 저알칼리 모르타르의 강도와 내구성능)

  • Lee, Byung-Jae;Kim, Bong-Kyun;Kim, Yun-Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.26 no.1
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    • pp.67-72
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    • 2022
  • Concrete prevents corrosion of reinforcing bars due to its strong alkalinity. However, in the sea, strong alkali components with a pH of 12 to 13 are eluted, which adversely affects the ecological environment and growth of marine organisms. In this study, the mechanical properties and durability of the low alkali mortar were evaluated for the development of a low alkali mortar for the 3D printed artificial reefs. As a result of evaluation of strength characteristics, the α-35 mixture, which were produced with fly ash, silica fume and α-hemihydrate gypsum, satisfied the strength requirement 27 MPa in terms of compressive strength. As a result of pH measurement, it was found that mixing with alpha-type hemihydrate gypsum resulted in minimizing pH due to the the formation of calcium sulfate instead of calcium hydroxide production. As a result of the chloride ion penetration resistance test, the α-35 mixture exhibited the best performance, 3844C. As a result of measuring the length change over time, the α-35 mixture showed the shrinkage 33.5% less compared to the Plain mix.