• International Journal of Highway Engineering
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• v.13 no.3
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• pp.31-38
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• 2011

As the percentage of permeable ground is reduced due to the increased impermeable roads of major cities, a heat island phenomenon can be dominantly observed, resulting in increased temperature. In addition, rainfall that would have been naturally absorbed and retained by the permeable ground is overflowed due to large volumes of run-off water, resulting in more sewer failures and increased erosion. In terms of permeable pavement system, block paving has been used anywhere as well as provides many years of service. The permeable block paving is an effective alternative to the more traditional asphalt or plain concrete for minor roads; furthermore, it looks a lot better than other pavements. In this study, the functional drainage evaluation of block paving was carried out, considering the usage of experimental sludge and wheel tracking test, in order to simulate the field condition of roads.

• Journal of Dental Anesthesia and Pain Medicine
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• v.21 no.2
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• pp.129-137
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• 2021

Background: Inappropriate use of intravenous and inhaled anesthetics may be dangerous in infants undergoing facial cleft surgeries. This study primarily aimed to compare the effect of infraorbital nerve block on sevoflurane requirement in infants undergoing cheiloplasty. Intraoperative opioid consumption, hemodynamics, blood glucose levels, extubation time, and delirium were also compared. Methods: This prospective, randomized, double-blinded study was conducted in 34 infants undergoing cheiloplasty under general anesthesia. After induction, group A received bilateral infraorbital nerve block with 0.5 mL of 0.5% bupivacaine and group B 0.5 mL saline. An increase in heart rate or blood pressure > 20% was managed by increasing sevoflurane by 2-2.5%, followed by fentanyl 0.5 ㎍/kg bolus. The chi-square test and independent-sample t-test were used where applicable. Results: Demographics, duration of surgery, and intravenous fluids used were comparable between the groups. Compared to group A, patients in group B had significantly higher consumption of fentanyl (14.2 ± 4.4 ㎍ vs. 22.1 ± 6.2 ㎍) and sevoflurane (14.2 ± 4.8 mL vs. 26.8 ± 15.6 mL). Intraoperative hemodynamic parameters were significantly lower in group A, the number of times increases in hemodynamic parameters occurred, and fentanyl supplemental bolus was required remained significantly lower in group A than in group B. Intraoperative glycemic levels remained higher in group B, and the extubation time was significantly shorter in group A than in group B (4.40 ± 1.60 min vs. 9.2 ± 2.18 min). Group A had a lesser occurrence of postoperative delirium. Conclusion: Supplemental infraorbital block in infants undergoing cheiloplasty under general anesthesia resulted in significantly decreased anesthetic requirements and optimal hemodynamic and glycemic levels with faster extubation and lesser delirium.

• Computers and Concrete
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• v.32 no.4
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• pp.351-363
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• 2023

Reducing the self-weight of reinforced concrete structures problem is discussed in this paper by using two types of self-weight reduction, the first is by using lightweight coarse aggregate (crushed brick) and the second is by using styropor block. Experimental and Numerical studies are conducted on (LWAC) lightweight aggregate reinforced concrete slabs, having styropor blocks with various sizes of blocks and the ratio of shear span to the effective depth (a/d). The experimental part included testing eleven lightweight concrete one-way simply supported slabs, comprising three as reference slabs (solid slabs) and eight as styropor block slabs (SBS) with a total reduction in cross-sectional area of (43.3% and 49.7%) were considered. The holes were formed by placing styropor at the ineffective concrete zones in resisting the tensile stresses. The length, width, and thickness of specimen dimensions were 1.1 m, 0.6 m, and 0.12 m respectively, except one specimen had a depth of 85 mm (which has a cross-sectional area equal to styropor block slab with a weight reduction of 49.7%). Two shear spans to effective depth ratios (a/d) of (3.125) for load case (A) and (a/d) of (2) for load case (B), (two-line monotonic loads) are considered. The test results showed under loading cases A and B (using minimum shear reinforcement and the reduction in cross-sectional area of styropor block slab by 29.1%) caused an increase in strength capacity by 60.4% and 54.6 % compared to the lightweight reference slab. Also, the best percentage of reduction in cross-sectional area is found to be 49.7%. Numerically, the computer program named (ANSYS) was used to study the behavior of these reinforced concrete slabs by using the finite element method. The results show acceptable agreement with the experimental test results. The average difference between experimental and numerical results is found to be (11.06%) in ultimate strength and (5.33%) in ultimate deflection.

• The Mathematical Education
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• v.26 no.1
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• pp.61-66
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• 1987

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.11-16
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• 2006

The object of this study is to develop new examination techniques for detecting the debonds in adhesive interface of different kinds of the material. Ultrasonic signal was modeled by theoretically analyzing ultrasonic propagation phenomenon of the adhesive interface and debonding interface. The test method using the phase reversal of the debonding interface applied to the FRP/Rubber test block. Aluminum/Rubber test block with the flat bottom hole was manufactured to quantitatively evaluate the minimum detection ability of the defects. The pulse echo reflection method and the phase reversal method were mutually compared and it was estimated that the phase reversal method could detect the debonds on the basis of the theoretically predicted ultrasonic signal and ultrasonic test data.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.2
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• pp.9-16
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• 2009

The object of this study is to develop new examination technique for detecting debond in adhesive interface of different kinds of materials. Ultrasonic signal was modeled by theoretically analyzing ultrasonic propagation phenomenon of the adhesive interface and debonding interface. The test method using the phase reversal of the debonding interface applied to the FRP/Rubber test block. Aluminum/Rubber test block with the flat bottom hole was manufactured to evaluate quantitatively the minimum detection ability of defects. The pulse echo reflection method and the phase reversal method were mutually compared and it was estimated that the phase reversal method could detect the debond on the basis of the theoretically predicted ultrasonic signal and ultrasonic test data.

• Resources Recycling
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• v.31 no.5
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• pp.42-51
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• 2022

Aggregate resources in Korea are expected to run out owing to an increase in development demand and construction investment. Recycled concrete aggregates (RCA), extracted from waste concrete, have a lower quality than natural aggregates. However, RCA can produce concrete similar in quality to the normal concrete by aggregate pretreatment, use of admixtures, and quality control. RCA are most suitable for use in precast concrete products such as sidewalk blocks and revetment blocks. Herein, the feasibility of producing revetment blocks using recycled aggregate concrete (RAC), similar in quality to normal concrete, was analyzed. The amount of RCA was varied, and moderate high early strength cement and steam curing were used to produce the concrete test blocks. In the block test, the load resistance characteristics of the blocks were evaluated to determine optimal RAC and glass fiber reinforced polymer (GFRP) rebar compositions. Thus, the variable that reduced the cement content was determined at the same level as that of natural aggregate concrete by the control of steam curing. In the concrete block test, although this depends on the reinforcement ratio, the RAC block exhibited the same or better performance than a normal concrete block. Therefore, the low quality of RCA in RAC is no longer a problem when concrete mixing and curing are controlled and appropriate reinforcement is used.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.176-182
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• 2018

One of the most important factor of esthetic prosthesis is the color of the teeth. Zirconia is produced in the process of design, milling, coloring, drying, and sintering. The effect of the drying degree of zirconia colorant on the color tone is examined. For the experiment, a total of 45 zirconia specimens(15 for each) were fabricated by using cad/cam system. The zirconia specimens(L block(LAZOR), Z block(Zircos-E block posterior), A block(AlphaZ)) were then subjected to zirconia sintering in accordance with the manufacturer's instructions, using a chemical coloring agent to Non-drying(0sec), intermediate (10sec), and completely dried (10min) temperature holding times. The color tone was measured using a spectrophotometer. The results were analyzed with a One-way analysis of variance and the Tukey post-hoc test (${\alpha}=.05$) The $L^*$ values of L, A specimens, $a^*$ values of A specimens, and $b^*$ values of Z specimens were not statistically different according to the degree of drying (p>0.05), While the $L^*$ value of Z specimen, $a^*$ value of L, Z specimen, $b^*$ values of L, A specimens were statistically different according to the degree of drying(p <0.05). In conclusion, the drying of zirconia colourants improves zirconia brightness and increases the optical properties of the enamel.

• Journal of Welding and Joining
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• v.33 no.4
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• pp.44-49
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• 2015

The structural epoxy adhesive used in car body assembly needs the highest level of joint mechanical strength under lap shear, T-peel and impact peel conditions. In this study, the effect of nano functionalized block copolymer addition on the impact peel strength of epoxy adhesive was investigated. DSC analysis showed that the addition of nano functionalized block copolymer did not affect the curing reaction of epoxy adhesive. From single lap shear test, it was found out that the addition of nano functionalized block copolymer slightly decreased the cohesive strength of cured adhesive layer. The addition of nano functionalized block copolymer showed beneficial effect on T-peel strength by changing the adhesive failure mode to the mixed mode. However, the addition of nano functionalized block copolymer just decreased the room temperature impact peel strength. It was considered that the addition of nano functionalized block copolymer could have effect on disturbing the crack propagation only for the case of slow strain rate.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.5
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• pp.59-66
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• 2017

Preeminent water treatment plans are essential to preserve the water quality of aquatic biotopes. Previous studies have not been sufficient to provide cost-effective maintenance method since they focused only on the purification of deteriorated water that requires a continuous supply of clean water. This study proposes an economical method of water quality maintenance using water treatment media block constructed vertically using porous ceramics, zeolite, and river pebble. The water treatment media block does not require a separate purification area because it functions as a purifier within the ecological pond which can maximize the biotope area. To evaluate the performance of the water treatment media block, we longitudinally tracked the change of water quality indicators (pH, TDS, COND, DO, T-P, T-N, COD) suggested by Water Environment Standards, Ministry of Environment, Republic of Korea. We compared the water quality of one control (A: general ecological pond composition method of the laminated structure) and two experimental groups (B: a combination of aquatic plants and a water treatment media block, C: a water treatment media block only). As a result, we confirmed that the water treatment media block is an efficient and economical method to maintaining the water quality of the ecological pond for a long time. The water treatment media block will be a great help in providing a better aquatic biotope space for aquatic insects and fishes living in clear water.