• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.2
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• pp.28-36
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• 2022

As port structures are exposed to various extreme external loads such as wind (typhoons), sea waves, or collision with ships; it is important to evaluate the structural safety periodically. To monitor the port structure, especially the rubber fender, a fender segmentation system using a vision sensor and deep learning method has been proposed in this study. For fender segmentation, a new deep learning network that improves the encoder-decoder framework with the receptive field block convolution module inspired by the eccentric function of the human visual system into the DenseNet format has been proposed. In order to train the network, various fender images such as BP, V, cell, cylindrical, and tire-types have been collected, and the images are augmented by applying four augmentation methods such as elastic distortion, horizontal flip, color jitter, and affine transforms. The proposed algorithm has been trained and verified with the collected various types of fender images, and the performance results showed that the system precisely segmented in real time with high IoU rate (84%) and F1 score (90%) in comparison with the conventional segmentation model, VGG16 with U-net. The trained network has been applied to the real images taken at one port in Republic of Korea, and found that the fenders are segmented with high accuracy even with a small dataset.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.195-201
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• 2022

This study aims to evaluate the feasibility of the disinfection of clinical ultrasound probes using the vapor fumigation method, which can quickly achieve high-level disinfection. Upon the inspection of the microbial contamination level of clinically used ultrasound probes, nine different types of bacteria were detected. The disinfection efficacy of 7.5% and 35% hydrogen peroxide (H₂O₂) was comparatively tested for the detected microbes. The 35% H₂O₂ demonstrated superior efficacy per disinfection duration. No significant change was observed in the rubber component of the ultrasound probes as a result of the 35% H₂O₂ disinfection treatment. The probes were contaminated with the microbes detected in the microbial contamination level inspection and subsequently disinfected using the novel medical disinfector that utilizes the vapor fumigation method. As a result, the disinfection using the novel device achieved 100% eradication of the microbes from the probes.This study demonstrates that the novel vapor fumigation method-based disinfector provides a faster and more powerful means of disinfection than the conventional disinfection methods. Therefore, the novel disinfector has the potential to be used as a convenient ultrasound probe disinfector in clinical settings.

• Journal of Dental Anesthesia and Pain Medicine
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• v.22 no.4
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• pp.305-314
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• 2022

Introduction: This clinical trial aimed to evaluate the anesthetic effect of the addition of 2 mg (4 mg/ml) of dexamethasone to 2% lidocaine (plain or with 1:80,000 epinephrine). The solutions were injected for a primary inferior alveolar nerve block (IANB) to provide mandibular anesthesia for the endodontic treatment of mandibular molars with symptomatic irreversible pulpitis. Methods: In a double-blinded setup, 124 patients randomly received either of the following injections: 2% lidocaine with 1:80,000 epinephrine, 2% lidocaine with 1:80,000 epinephrine mixed with 2 mg dexamethasone, or plain 2% lidocaine mixed with 2 mg dexamethasone, which were injected as a primary IANB. Ten minutes after injection, patients with profound lip numbness underwent electric and thermal pulp sensibility tests. Patients who responded positively to the tests were categorized as "failed" anesthesia and received supplemental anesthesia. The remaining patients underwent endodontic treatment using a rubber dam. Anesthetic success was defined as "no pain or faint/weak/mild pain" during endodontic access preparation and instrumentation (HP visual analog scale score < 55 mm). The effect of the anesthetic solutions on the maximum change in heart rate was also evaluated. The Pearson chi-square test at 5% and 1% significance was used to analyze anesthetic success rates. Results: The 2% lidocaine with 1:80,000 epinephrine, 2% lidocaine with 1:80,000 epinephrine mixed with 2 mg dexamethasone, and plain 2% lidocaine mixed with 2 mg dexamethasone groups had anesthetic success rates of 34%, 59%, and 29%, respectively. The addition of dexamethasone resulted in significantly better results (P < 0.001, 𝛘² = 9.07, df = 2). Conclusions: The addition of dexamethasone to 2% lidocaine with epinephrine, administered as an IANB, can improve the anesthetic success rates during the endodontic management of symptomatic mandibular molars with irreversible pulpitis.

• Composites Research
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• v.35 no.3
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• pp.127-133
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• 2022

Polypropylene (PP) has been received great attention as a next-generation high-voltage power cable insulation material that can replace cross-linked polyethylene (XLPE). However, the PP cannot be used alone as an insulation material because of its high elastic modulus and vulnerability to impact, and thus is mainly utilized as a form of a copolymer with rubber phases included in the polymerization step. In this paper, a soft PP-based blend was prepared through melt-mixing of impact PP, polyolefin elastomer, and propylene-ethylene random copolymer. The elastic modulus and impact strength of the blend could properly be decreased or increased, respectively, by introducing elastomeric phases. Furthermore, the blends showed a high storage modulus even at a temperature of 100℃ or higher at which the XLPE loses its mechanical properties. In addition, the blend was found to be effective in suppressing the space charge compared to the pristine PP as well as XLPE.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.293-299
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• 2022

Recently, various stakeholder are interested in microplastic to cause pollution of the marine's ecosystem and effort to conduct study of product's life cycle to reduce pollution of marine's ecosystem. The micorplastic refer to materials of the nano- to micro- sized units and it can be classified into primary and secondary. The primary microplastic mean the manufactured for use in the specific field such as the microbead of the cosmetic or cleanser. also, secondary mean the unintentionally generated during use of the product such as the textile crumb by the doing the laundry. Tire and Road Wear Particles(TRWPs) are also defined as secondary microplastic. Typically, TRWPs are created by friction between the tread compound's rubber of the tire and the surface of the road du ring the driving cars. Most of the generated TRWPs exist on the roadside and some of them were carried to marine by the rainwater. In this study, we perform the quantitative analysis of the TRWPs existed in fine dust at the roadside. So, we collected the dust from the roadside in Chungcheongnam-do's C site with a movement of 1,300 cars per the hour. The collected samples were separated according to size and density. And shape analysis was performed using the Scanning Electron Microscope(SEM). We were possible to discover a lot of TRWPs at the fine dust of the 100 ± 20 ㎛. And we analysis it u sing the Thermo Gravimetric Analysis(TGA) and Gas Chromatography/Mass Spectrometer(GC/MS) for the quantitative components from the tire. As a result, it was confirmed that TRWPs generated from the roadside fine dust were included the 0.21 %, and the tire and road components in the generated TRWPs consisted of the 3:7 ratio.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.154-160
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• 2021

Recently, there have been increasing construction works carried out in urban centers, which are inducing frequent artificial vibration in the vicinity of existing structures due to such construction works. moreover, in case of industrial estates, vibration is induced due to operation of machines in the surrounding areas, thereby causing problems. meanwhile, in case of ordinary concrete that compose structure has low level of damping capability for vibration. accordingly, there are difficulties in blocking a wide range of vibrations delivered to the structures from outside including not only vibrations generated in the structures themselves but also ground vibration. recently, numerous studies are being carried out actively on high-damping system that markedly enhanced the damping performances of structures by utilizing polymer concrete in order to block the vibrations delivered to the structures through ground. therefore, this study compared the performances of polymer concrete with those of ordinary concrete, polyurethane pad and foamed rubber pad in order to review its performances in reducing ground vibration. for this purpose, review of FRF and vibration acceleration as dynamic characteristics was made. after comparative verification on the dynamic characteristics is made when polymer concrete and other aforementioned materials are applied to underground structures, the possibility of application of polymer concrete to structures is reviewed.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.561-568
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• 2021

In this study, in order to observe the change in the amount of Tire and Road Wear Particles and the ratio of tire components in it according to the tire wear resistance performance, carried out the evaluation by varying the vulcanization reaction design of the tire tread rubber. In addition, in order to improve the reliability of the evaluation of Tire and Road Wear Particles, the evaluation was performed indoor laboratory test equipment that simulates the condition on real driving to exclude various environmental influences including minerals, driver's habits, road surface, weather, tire structure and pattern designs. After the evaluation in closed space, it is estimated that the amount of collected Tire and Road Wear Particles is 84% compared to 100% of the tire and road wear loss weight, of which 96.4~97.7% was around the road and 2.3~3.6% was in the air. As a result of analy sis of the collected Tire and Road Wear particles, the tire component existed 63~75% in the Tire and Road Wear Particles depending on the wear resistance performance of the tire.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.77-83
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• 2022

This study was conducted to determine the optimal composition of sex attractant for monitoring adults of the tobacco cutworm, Spodoptera litura, in Korea. Lures of different compositions from the two sex pheromone components the female, (Z,E)-9,11-tetradecadienyl acetate (Z9E11-14:Ac) and (Z,E)-9,12-tetradecadienyl acetate (Z9E12-14:Ac), were compared for male attraction using synthetic chemicals, rubber septa, and funnel traps in soybean and peanut fields. After sequential tests were conducted using three sets of the two components different ranges from 5:5 to 10:1, from 9:1 to 99:1, and from 9:1 to 39:1, the 19:1 ratio was identified as the most efficient composition. However, S. litura males were barely caught in the trap of the Z9E11-14Ac single component lure. The results show that both the sex attractant compounds are necessary for monitoring adults S. litura males. The higher the pheromone amount in the dispenser in the range from 0.1 to 10 mg, the more males were attracted. Furthermore, the trap height of 1.5 m was optimal for male capture.

• Journal of Science Education
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• v.46 no.3
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• pp.223-236
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• 2022

The purpose of this study is to investigate pre-service elementary teachers' awareness on the sources of microplastics. The participants were 75 male and 91 female undergraduates. A 15-item survey questionnaire was developed based on prior researches regarding microplastics emission sources and were modified through expert review and preliminary research. The survey results show that over 80% of the respondents had heard of microplastics before through news, internet, TV, etc. However, they tended not to be aware that things such as lab coats, wet tissue, dust protective mask, or paper cup were made of microplastics-causing substances. For the questions on the expected situation of microplastics contamination, the frequency of their choices were relatively low in 'Tires of cars running are worn out' and 'The gum stuck to the floor becomes smaller.' These results show that many of them were not aware that synthetic fiber or synthetic rubber was one of the microplastics emission sources. Gender differences were found in the attitudes toward microplastics problems. Female students are more interested in the issues and are more willing to participate in the solution, and recognize the need for more education on microplastics. The implications and future directions for science education were discussed.

• Applied Chemistry for Engineering
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• v.34 no.4
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• pp.388-396
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• 2023

The evaluation of fire risk for combustible materials was carried out using Chung's equations-X, Chung's equations-XI, and Chung's equation-XII, which were newly established. The fire risk index-XII (FRI-XII) and fire risk rating (FRR) were calculated for specimens including camphor tree, cherry, rubber tree, and elm. The combustion characteristics were determined using a cone calorimeter according to ISO 5660-1. Chung's equations caculated the fire performance index-X (FPI-X) and fire growth index-X (FGI-X) values ranged from 89.34 to 1696.75 s² /kW and from 0.0006 to 0.0107 kW/s² , respectively. In addition, the fire performance index-XI (FPI-XI) and fire growth index-XI (FGI-XI) varied from 0.08 to 1.48 and from 0.67 to 11.89, respectively. The fire risk index-XII (FRI-XII), which is an indicator of fire risk, showed that camphor tree had a value of 148.63 (fire risk rating: G), indicating a very high fire risk. This suggests that combustible materials with a high concentration of volatile organic compounds have lower FPI-X and FPI-XI values, higher FGI-X and FGI-XI values, and consequently higher FRI-XII values, indicating an increased fire risk.