• Korean Journal of Agricultural Science
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• v.43 no.2
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• pp.194-204
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• 2016

The pear psylla, Cacopsylla pyricola, is a very small sap-feeding insect of many commercial pear varieties that could be considered the most serious insect pest of pear. Detailed information on plant penetration activities of the pear psylla is essential to study its feeding behavior used to evaluate resistant traits to chemical control. The application of the electrical penetration graph technique (EPG) could provide a relevant insight into the nature of this resistance. EPG waveforms of C. pyricola were characterized on the basis of amplitude, frequency, voltage level, and electrical origin. Feeding behaviors of C. pyricola were recorded and analyzed by EPG analysis. During EPG monitoring, waveform PA occurred at the start of stylet penetration of pear leaf epidermal cell. Waveform PB followed, in which stylet secreted saliva was observed. Waveforms PC1 and PC2 involved penetrating and sucking behaviors in parenchyma cells and vascular parenchyma, respectively. In addition, waveform PC1 represented salivation into bundle sheath cells and ingestion from parenchyma. Otherwise, behaviors of salivation into phloem and ingestion from phloem produced waveforms PE1 and PE2, respectively. On the other hand, ingestion from xylem tissues showed waveform PG. Among the feeding patterns of C. pyricola described above, phloem feeding patterns occurred most frequently, followed by xylem feeding and parenchyma penetration patterns in descending order.

• Restorative Dentistry and Endodontics
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• v.26 no.5
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• pp.379-386
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• 2001

This study was performed to evaluate the sealing ability of various retrograde filling materials by using bacterial penetration and dye penetration test. One hundred and forty extracted human teeth with single, straight canals and mature apiece were collected and used for this study. All canals were instrumented using an engine driven Ni-Ti file (ProFile). After removing 3mm from the apex of tooth, a standardized 3mm root end cavity was prepared using an ultrasonic instrument. The 70 teeth were randomly divided into 7 groups : 6 groups for retrograde filling using Super-EBA, ZOE, Chelon-Silver, IRM, ZPC and amalgam. The 7th group was used as a negative control. Nail varnish was applied to all external root surfaces to the level of the reseated root ends to prevent lateral microleakages. The specimens were then sterilized in an ethylene oxide sterilizer for 24 hours. 2 mm of the reseated root was immersed in a culture chamber containing a Tripticase Soy Broth with a phenol red indicator. The coronal access of each specimen was inoculated every 72 hours with suspension of Proteus vulgaris. The culture media were observed every 24hours for color change indicating bacterial contamination. The specimens were observed for 4weeks. The remaining 70 teeth were submitted to a dye penetration test. The canals of all teeth were first sealed with AH26 and obturated using an Obtura II system. Root resection, root end preparation and retrograde filling was performed as above. All specimens were suspended in 2% methylene blue dye for 72 hours before being ion gitudinally split. The degree of dye penetration was then measured using a stereomicroscope at 10 magnification and evaluated. The results were as floows : 1. In the bacterial penetration, the degree of leakage was the lowest in the Super-EBA, followed by, in ascending order, ZOE, Chelon-Silver IRM and ZPC. The amalgam showed highest bacterial leakage of all(p<0.01). 2. In the dye penetration, the degree of microleakage was the lowest in the Chelon-Silver and Super-EBA, followed by, in ascending order, IRM, ZPC. The ZOE and amalgam showed the highest microleakage of all (p<0.05). These results suggested that the eugenol based cement, Super-EBA, have excellent sealing ability as a retrograde filling material.

• Geomechanics and Engineering
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• v.13 no.3
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• pp.475-488
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• 2017

Geotechnical data contributes substantially to the cost of engineering projects due to increasing cost of site investigations. Existing information in the form of soil maps can save considerable time and expenses while deciding the scope and extent of site exploration for a proposed project site. This paper presents spatial interpolation of data obtained from soil investigation reports of different construction sites and development of soil maps for geotechnical characterization of Multan area using ArcGIS. The subsurface conditions of the study area have been examined in terms of soil type and standard penetration resistance. The Inverse Distance Weighting method in the Spatial Analyst extension of ArcMap10 has been employed to develop zonation maps at different depths of the study area. Each depth level has been interpolated as a surface to create zonation maps for soil type and standard penetration resistance. Correlations have been presented based on linear regression of standard penetration resistance values with depth for quick estimation of strength and stiffness of soil during preliminary planning and design stage of a proposed project in the study area. Such information helps engineers to use data derived from nearby sites or sites of similar subsoils subjected to similar geological process to build a preliminary ground model for a new site. Moreover, reliable information on geometry and engineering properties of underground layers would make projects safer and economical.

• Korean Journal Plant Pathology
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• v.2 no.3
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• pp.199-206
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• 1986

Penetration level, female development and histological changes in infected root tissues were investigated following inoculation with different inoculum levels (110,440 and 1760 juveniles/plant) of Heterodera glycines (SCN) race 3 on susceptible 'Lee' and resistant 'Pickett' soybean cultivars. Penetration level was lower in Pickett at the higher inoculum levels but no differences were detected in Lee. However, the lower penetration level in the resistant soybean cultivar appeared not to be directly related to plant resistance (female maturation). The number of females recovered from Lee was lower at the highest inoculum level. The number of females maturing on Pickett was much less than that on Lee, showing that changes of SCN population is associated with the number of SCN maturing rather than nematode penetration. In Lee mono-infection sites (a single nematode per site) syncytia had dense cytoplasm and no central vacuoles. while multi-infected sites (many overlapping nematodes per site) had syncytia with a large central vacuole and many small vacuoles. Resistant responses in mono-and multi-infected root tissues of Pickett were delayed and rapid necrosis, respectively. The differences in tissue response are suggested as a mechanism that controls density-dependent population changes in resistant and/or susceptible soybean cultivars.

• Journal of Digital Convergence
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• v.2 no.2
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• pp.63-76
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• 2004

There is a considerable gap in the level of the Internet access charges among countries because of the history of the Internet use, current status of the Internet infrastructure, the Internet penetration rate, and so on. Low Internet access charge increases the number of the Internet users and the Internet penetration rate, which boosts economic activities. This paper empirically explores the impacts of the internet access charges on economic activities using a cross-country analysis based on data from 76 countries for the year 1998-2001. To this end, several versions of the neoclassical growth models, explicitly including the internet access charges, are estimated with the GDP used for a proxy for economic activities and the level of Internet access charges considered as an input to production. Subject to the appropriate caveats, the results show that the level of the Internet access charges make a significantly negative effect on economic activities. In other words, it is concluded that low Internet access charges of a county increase economic activities and the increased economic activities in turn raise the real income of the county.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.6
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• pp.1-7
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• 2015

Most of chloride diffusion models based on finite difference method (FDM) could not express the diffusion in horizontal direction at each elevation. To overcome these weakness, two dimensional chloride ion penetration model based on finite element method (FEM) to be able to combine various multi-physics simultaneously was suggested by introducing moving mesh technique. To avoid the generation of mesh being able to be distorted depending on the relative movement of water level to static concrete, a rectangular type of mesh was intentionally adopted and the total number of meshes was empirically selected. The simulated results showed that the contents of surface chloride decreased following to the increase of elevation in the top part of low sea level, whereas there were no changes in the bottom part of low level. In the DuraCrete model, the diffusion coefficient of splashed zone is generally smaller than submerged zone, whereas the trend of Life365 model is reverse. Therefore, it could be understood that the developed model using moving mesh technique effectively reflects $DuraCrete^{TM}$ model rather than $Life365^{TM}$ model. In the future, the model will be easily expanded to be combined with various multi-physics models considering water evaporation, heat of hydration, irradiation effect of sun and so on because it is based on FEM.

• Journal of Pharmaceutical Investigation
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• v.30 no.4
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• pp.247-252
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• 2000

The advantages of transdermal administration are avoiding hepatic first pass effect, minimizing inter- and intra-patient variation, maintaining steady-state plasma level to provide long-term therapy from a single dose, and allowing a rapid termination of drug input. Clenbuterol, a selective ${\beta}_2-adrenergic$ receptor stimulant, has been introduced as a potent bronchodilator for patients with bronchial asthma, chronic obstructive bronchial disease. For the development of transdermal systems containing clenbuterol, two limiting factors - long lag time and low flux - must be overcome. In this study, we attempted to select optimal formulation for preparation of clenbuterol patch using hairless mouse skin and flow-through diffusion cell. The flux of clenbuterol increased as the percent of clenbuterol dose dependently in the concentration range of 5-15%. Based on this result, we fixed the concentration of clenbuterol as 15%. The effect of various penetration enhancers on percutaneous absorption of clenbuterol through hairless mouse skin was investigated. Labrafil was the most effective enhancer, which increased the permeability of clenbuterol approximately 4-fold compared with the control without penetration enhancer. Optimal enhancer concentration was 3%. The effect of various adhesives on penetration of clenbuterol was also investigated. Among the adhesives studied, MA-31 was the most effective adhesive. Furthermore, the clenbuterol patch composed of 15% clenbuterol, 3% Labrafil and 82% MA-31, which gave most excellent penetration of drug in in vitro penetration study, maintained therapeutic plasma levels in in vivo study using S.D. rats. These studies demonstrated a good feasibility of clenbuterol administration through the intact skin using a transdermal patch, and show a possibility of the development of clenbuterol patches.

• Korean Journal of Labor Studies
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• v.23 no.1
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• pp.197-220
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• 2017

This paper provides empirical evidence on the impact of increasing import penetration on the job stability of Korean workers. The main results are as follows. First, import penetration negatively affects job stability. If an industry's ratio of imports to total supply increases by 1 percentage point, the turnover probability of workers in that industry increases by 4.5 percentage points. Second, the effect of trade liberalization is not symmetric between imports and exports. Unlike the case of imports, an industry's ratio of exports to output does not have a significant effect on job stability. Third, the impact of import penetration is not uniform across different types of workers. The negative impact is greater for workers in small firms, less educated workers, and those not protected by labor unions.

• International Journal of Highway Engineering
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• v.8 no.4 s.30
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• pp.125-133
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• 2006

In this study, the Korean Industrial Standard(KS) penetration grade system was examined to evaluate its statistical validity. It was found from this limited study that the system has no gap between each grade, the binder falling out of limit trespasses into other binder grade. Therefore, many products can have similar property level with an adjacent grade even though the mean value is within the specification limit. It was also found out that the equal range setup of each grade, such as 20 for 40-60, 60-80, 80-100, has no statistical foundation. Since KS penetration grade is defined without gap between each grade, the producer must maintain the coefficient of variation below the level by the ASTM system to satisfy the normal quality control limit of products. Due to its lack of a gap between grades, higher percentage of products will be duplicated even if the mean is at the median of the specification limits due to material's quality uncertainty. Especially if the mean moves toward the upper limit, a half or more of the binder grade will be overlapped with the upper binder grade. Therefore, KS penetration specification should be immediately modified by statistically valid methodologies.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.561-577
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• 2021

The compacted bentonite buffer in a geological repository for high-level radioactive waste disposal is saturated due to groundwater inflow. Saturation of the bentonite buffer results in bentonite swelling and bentonite penetration into the rock discontinuities present around the disposal hole. The penetrated bentonite is exposed to groundwater flow and can be eroded out of the repository, resulting in bentonite mass loss which can affect the physical integrity of the engineered barrier system. Hence, the evaluation of buffer-rock interactions and coupled behavior due to groundwater inflow and bentonite penetration is necessary to ensure long-term disposal safety. In this study, the effects of the bentonite penetration and swelling on the physical properties of jointed rock mass were evaluated using the quasi-static resonant column test. Jointed rock specimens with bentonite penetration were manufactured using Gyeongju bentonite and hollow cylindrical granite rock discs obtained from the KAERI underground research tunnel. The effects of vertical stress and saturation were assessed using the P-wave and S-wave velocities for intact rock, jointed rock and jointed rock with bentonite penetration specimens. The joint normal and joint shear stiffnesses of each joint condition were inferred from the wave velocity results assuming an equivalent continuum. The joint normal and joint shear stiffnesses obtained from this study can be used as input factors for future numerical analysis on the performance evaluation of geological waste disposal considering rock discontinuities.