• Journal of the Korean Geosynthetics Society
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• v.17 no.2
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• pp.33-40
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• 2018

Characteristics of interface friction between cohesionless soils and geotechnical structure surfaces play an important role in the analysis of earth load and resistance on the structure. In general, geotechnical structures are mainly composed of either steel or concrete, and their surface roughnesses with respect to soil particle sizes influence the interface characteristics between soils and the structures. Accurate assessment of the interface friction characteristics between soils and structures is important to ensure the safety of geotechnical structures, such as mechanically stabilized earth walls reinforced with inextensible reinforcements, piles embedded into soils, retaining wall backfilled with soils. In this study, based on the database of high quality interface friction tests between frictional soils and solid surfaces from literature, equation representing peak interface friction angle is proposed. The influential factors of the peak interface friction angle are relative roughness between soil and solid surface, relative density of frictional soil, and residual (constant volume) interface friction angle. Futhermore, for the developed equation of the interface friction angle, its uncertainty was assessed statistically based on Goodness-of-fit test results.

• Journal of Periodontal and Implant Science
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• v.26 no.1
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• pp.47-67
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• 1996

The purpose of this study was to observe the effect of $Biocoral^R$ graft and bioglass 45S5 graft in combination with ePTFE membrane in periodontal osseous defects for new bone formation. Nine healthy dogs were used. Under general anesthesia, 3-wall defects were created on the mesial and distal surfaces of the maxillary right canines, the mesials of the maxillary right second premolars, the distals of the mandibular right canines and the mesials of the mandibular right third premolars. To induce periodontitis, a silicone rubber, $Provil^R$ light body, was injected under pressure into the defects. Ninety days later, $Provil^R$was removed and followed by thorough root planing. The followings were then applied in the mesial and distal defects of the maxillary right canines, the mesials of the maxillary right second premolars, the distals of the mandibular right canines and the mesials of the mandibular right third premolars by random selections : 1) ePTFE membrane only application, 2) $Biocoral^R$ graft, 3) $Biocoral^R$ graft and ePTFE membrane application, 4)Bioglass 45S5 graft, 5) Bioglass 45S5 graft and ePTFE membrane application. The membranes were removed 1 month later. The dogs were sacrified at 1, 2 and 3 months following the graft, and block sections were made, demineralized, embedded, stained and examined by light microscope and transmission electron microscope. On the sections from teeth treated with ePTFE membrane only, the defect demonstrated extensive connnective tissue and alveolar bone regeneration. The $Biocoral^R$ graft group demonstrated extensive bone regeneration compared with ePTFE membrane only group. In the $Biocoral^R$ graft plus ePTFE membrane group, regeneration of new alveolus and crest occurred within the defect. As the experimental period lengthened, bone regeneration was increased and bone bridge was formed among the graft particles. The but bioglass 45S5 graft group demonstrated extensive bone regeneration but the amount of new bone was less than that of the $Biocoral^R$ graft group. For the bioglass 45S5 graft plus ePTFE membrane group, the amount of new bone was also increased. As the experimental period lengthened, bone regeneration was increased. Multinucleated giant cells, fibroblasts and macrophages were observed. As the bone formation was increased, the number of such cells was decreased. In conclusion, the $Biocoral^R$ was found better than the bioglass 45S5 for new bone formation, and the use of ePTFE membrane alone or with $Biocoral^R$/bioglass 45S5 can be supported as potential methods of promoting bone formation.

• Journal of the Korean GEO-environmental Society
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• v.17 no.9
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• pp.5-12
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• 2016

Numerical analyses were carried out to simulate tilting control on the suction pile for offshore wind power embedded into cohesive soil and cohesionless soil using finite element software, ABAQUS. A 3-dimensional suction pile was modelled as a wished-in-place pile with $1^{\circ}$ tilted from vertical line. The inner room of suction pile was divided into 3 separate rooms for tilting control, and point load was applied to the center of gravity of a separate room to restore the original position of the suction pile. From numerical analyses, required suction pressure was obtained for desired tilting degree, and the maximum/minimum principle stresses of concrete skirt and the Mises stresses of inner steel wall were collected at original position. It was found that the required suction pressure was about 410 kPa for cohesive soil, and about 1,800 kPa for cohesionless soil.; likewise, obtained stresses were greater for cohesionless soil than cohesive soil.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.4
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• pp.366-376
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• 2013

The purpose of this study is to evaluate the marginal and internal fit of coping made by CAD/CAM using different scanning methods. Zirconia coping was made by each CAD/CAM system followed by intra-oral scanning, model optical scanning and model contact scanning. It was embedded into Epoxy Resin and was cut by buccal to lingual. AMD (Absolute marginal discrepancy), MG (Marginal gap), GA (Gap of axial), GL (Gap of line angle) and GO (Gap of occlusal) of each sample were measured. The result is as followed; 1. The mean value of AMD in Group 1, Group 2, Group 3 are $141.21{\pm}42.94{\mu}m$, $140.63{\pm}31.64{\mu}m$, $109.37{\pm}28.42{\mu}m$. The averages of MG in Group 1, Group 2, Group 3 are $82.52{\pm}43.99{\mu}m$, $90.28{\pm}27.93{\mu}m$, $66.55{\pm}28.77{\mu}m$. Statistically there is no difference in AMD and MG among the three Groups (Anova, P>0.05). 2. GA of Group 2 revealed statistically difference compared with Group 1 and Group 3 (Anova, P<0.05). 3. GL and GO of Group 1 showed statistically significant differences compared with Group 2 and Group 3 (Mann-whitney test (P<0.05). Zirconia copings made by 3 ways of scanning methods have no difference with conventional ceramics in AMD and MG which are known as the most important factors.

• Journal of the Korea Society of Computer and Information
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• v.18 no.10
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• pp.97-107
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• 2013

The latest programming paradigm has been mostly geared toward object-oriented programming and visual programming based on the object-oriented programming. However, object-oriented programming has a more difficult and complicated concept compared with that of existing structural programming technique; thus it has been very difficult to educate students in the IT-related department. This study designed and implemented a Java robot training kit in which the Java virtual machine is built so that it may enhance the desire and motivation of students for learning the object-oriented programming using the training kit which is possible to attach various input and output devices and to control a robot. The developed Java robot training kit is able to communicate with a computer through the USB interface, and it also enables learners to manufacture a robot for education and to practice applied programming because there is a general purpose input and output port inside the kit, through which diverse input and output devices, DC motor, and servo motor can be operated. Accordingly, facing the IT fusion era, the wall between the academic circles and the major becomes lower and the need for introducing education about creative engineering object-oriented programming language is emerging. At this point, the Java robot training kit developed in this study is expected to make a great commitment in this regard.

• Journal of the Korea Institute of Building Construction
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• v.18 no.1
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• pp.17-24
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• 2018

The pullout test, a nondestructive testing(NDT), for pre-installed inserts is perhaps the most widely used technique to estimate the in-situ compressive strength of concrete. It measures the force needed to pullout a standardized metal insert embedded into concrete members. The pullout test was certified by the American Society for Testing and Materials(ASTM) and Canadian Standards Association(CSA) as a reliable method for determining the strength of concrete in concrete structures under construction. To easily estimate the strength of ultra-high-strength concrete, a simplified pullout tester, primarily composed of a standard 12mm bolt with a groove on the shaft as a break-off bolt, an insert nut, and a hydraulic oil pump without a load cell, was proposed. Four wall and two slab specimens were tested for two levels of concrete strength, 80MPa and 100MPa, using a simplified pullout tester with a load cell to verify the advantages of the pullout test and simplified pullout test. The compressive strength of concrete, pullout load, and the rupture of the break-off bolt were measured 11 times, day 1 to 7, 14, 21, 28, and 90. The correlation of the pullout load and the compressive strength of each specimen show a higher degree of reliability. Therefore, a simplified pullout test can be used to evaluate the in-place strength of ultra-high-strength concrete in structures. The prediction equation for the groove diameter of the break-off bolt(y) with the concrete strength(x) was proposed as y=0.0184x+5.4. The results described in this research confirm the simplified pullout's utility and potential for low cost, simplicity, and convenience.

• Parasites, Hosts and Diseases
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• v.29 no.1
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• pp.21-30
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• 1991

An immunohistochemical study was performed to demonstrate comparative antigenicity of each body structure of the liver fluke, Clonorchis sinensis, such as the digestive tract, reproductive organs, excretory system, tegument and suckers. Indirect immunoperoxidase technique was applied, rising formalin-fixed and paraffin-embedded sections of C. sinensis as the antigen. Pooled cat sera obtained 10 weeks after an experimental infection with C. sinensis and peroxidase-conjugated goat anti-cat IgG were used as the primary and secondary antibodies, respectively. The intensity of immunohistochemical stain was very sensitive upon the titers of the primary and secondary antibodies, and their optimum dilutions were found to be 1:1,000∼1:2,000 and 1:1,000, respectively. The intestinal epithelial cells, intestinal content and excretory bladder showed strong positive coloring reactions even at lower titer (1 : 2,000) of the primary antibody, whereas the uterine wall and eggs, vitelline glands, and male reproductive organs showed only weak positive reactions despite an increase in the antibody titer (1:1,000). On the other hand, the suckers, tegument, subtegumental cells and other parenchyme portions did not reveal any positive immunoperoxidase reaction at the same antibody titers. From the above results, it is highly suggested that the most potent antigenicity of C. sinensis occur from their excretory-secretory substances originated from the digestive and excretory organs.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.5
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• pp.79-86
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• 2009

With the substantial increase of the size of structure, the management of excavation becomes more difficult. Therefore, massive collapses which are related to retaining wall recently increase. However, since the study on measuring and monitoring the pre-stressing force of anchor is insufficient, behavior of anchor may not be predicted and monitored appropriately by the existing strain gauge and load cell type monitoring system. FBG Sensor, which is smaller than strain gauge and has better durability and does not have a noise from electromagnetic waves, is adapted to measure the strain and pre-stressing force of 7-wire strand, so called smart tendon. A series of pullout tests were performed to verify the feasibility of smart tendon and find out the load transfer mechanism around the steel wire tendon fixed to rock with grout. Distribution of measured strains and estimated shear stresses are compared with those predicted by theoretical solutions. It was found that developed smart tendon can be used effectively for measuring strain of 7-wire strand anchor and theoretical solutions underestimate the magnitude of shear stress and load transfer depth.

• Science of Emotion and Sensibility
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• v.24 no.2
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• pp.65-74
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• 2021

With recent innovations in the ICT industry, the demand for wearable sensing devices to recognize and respond to biological signals has increased. In this study, a three-dimensional (3D) spacer fabric was embedded in a single-wall carbon nanotube (SWCNT) dispersive solution through a simple penetration process to develop a monolayer piezoresistive pressure sensor. To induce electrical conductivity in the 3D spacer fabric, samples were immersed in the SWCNT dispersive solution and dried. To determine the electrical properties of the impregnated specimen, a universal testing machine and multimeter were used to measure the resistance of the pressure change. Moreover, to examine the changes in the electrical properties of the sensor, its performance was evaluated by varying the concentration, number of penetrations, and thickness of the specimen. Samples that penetrated twice in the SWCNT distributed solution of 0.1 wt% showed the best performance as sensors. The 7-mm thick sensors showed the highest GF, and the 13-mm thick sensors showed the widest operating range. This study confirms the effectiveness of the simple process of fabricating smart textile sensors comprising 3D spacer fabrics and the excellent performance of the sensors.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.2
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• pp.351-360
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• 2000

The purpose of this study was to evaluate the microleakage of class V compomers according to acid etching treatment and treatment times. Extracted 180 sound human molar teeth were selected then prepared physiologic pulpal pressure far this experiment. In this study class V cavities were prepared on buccal surface with gingival margin located in 1mm superior to CEJ under simulate physiological conditions. These specimens were randomly divided into 6 groups of 30 each and restored following methods : A: Dyract AP + Prime&Bond 2.1 Group 1 : No acid etching, according to manufacturer's instruction. Group 2 : 15 seconds acid etching and same method with Group 1. Group 3 : 30 seconds acid etching and same method with Group 1. B: F2000 groups + Single Bond adhesive Group 1 : No acid etching, according to manufacturer's instruction. Group 2 : 15 seconds acid etching and same method with Group 1 Group 3 : 30 seconds acid etching and same method with Group 1. After 500 thermocycling between $5^{\circ}C\;and\;55^{\circ}C$, the specimens were sealed with glass ionomer and nail varnish then placed in 5% methylene blue dye for 5 hours and rinsed with tab water. The specimens were embedded in orthodontic clear resin, then sectioned buccolingually through the center of restoration with a low speed diamond saw. The dye penetration on each of the specimens were then observed with a stereomicroscope at $\times20$ magnification. The results of this study were statistically analyzed using the indepedent sample t-test and analysis of variance. Results were as follows, 1. In occlusal walls, microleakage were significantly reduced in acid etched group restored with Dyract AP but no statistically significance in F2000 groups. 2. In gingival walls, microleakage were significantly reduced in group 2 restored with Dyract AP, and group 2 and group 3 in F2000 groups. 3. All groups, except group 3 in Dyract AP, showed significantly less microleakage in occlusal wall than gingival wall. 4. No statistical significance were showed between group 2 and group 3 in both materials.