• Journal of the Korean Geosynthetics Society
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• v.20 no.1
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• pp.9-19
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• 2021

This paper deals with the reinforcement performance of acrylate for reinforcing the settled railway roadbed. Concrete tracks have the advantage of reducing track maintenance costs and high resistance to track destruction. However, roadbed settlement is occurring in some construction sections, and the safety of railways is a serious concern because of difficulties in maintenance. Currently, maintenance through the track restoration method is being carried out in Korea as a way of roadbed settlement in concrete tracks, but continuous re-settlement can occur because the roadbed itself cannot be reinforced, and there are very few cases of reinforcement of railway roadbeds and field application. So the development of reinforcement materials and construction methods to reinforce railway roadbeds is required. Therefore, in this paper, acrylate was selected as reinforcement material for railway roadbed, and the reinforcement performance of acrylate was analyzed through experiment. As a result, it was analyzed that the acrylate can penetrate into a permeability coefficient of 1×10^-4 cm/sec, and secure uniaxial compression strength of 0.5 MPa/30min or more and stiffness of 80 MPa or more.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.24 no.4
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• pp.357-365
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• 2021

Purpose: A change in diagnosis from ulcerative colitis (UC) to Crohn's disease (CD) has been reported in pediatric inflammatory bowel disease; however, only a few clinical characteristics and predictors of this diagnostic change have been reported. We aimed to describe the clinical characteristics of patients with UC who underwent a change in diagnosis to CD and identify variables associated with the change. Methods: The medical records of pediatric patients with UC who were followed up at the National Center for Child Health and Development between 2006 and 2019 were retrospectively reviewed. Clinical data on disease phenotype, laboratory parameters, endoscopic findings, and treatment of patients whose diagnosis changed to CD (cCD) were compared to those of patients whose diagnosis remained UC (rUC). Results: Among the 111 patients initially diagnosed with UC, 11 (9.9%) patients were subsequently diagnosed with CD during follow-up. There was no significant difference between the cCD and rUC groups in terms of sex, age at initial diagnosis, and the extent and severity of disease at initial diagnosis. Albumin and hemoglobin levels were significantly lower in the cCD group than in the rUC group. The proportion of patients who required biologics was significantly higher in the cCD group than in the rUC group (p<0.05). Conclusion: Approximately 10% children initially diagnosed with UC were subsequently diagnosed with CD. Hypoalbuminemia and anemia at initial diagnosis and use of biologics could be predictors of this diagnostic change.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.763-769
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• 2021

In this study, ionic liquids were synthesized to remove carbon dioxide (CO2) on a laboratory scale. The vapor-liquid absorption equilibrium device (VLE) was used to investigate the carbon dioxide absorption capacity. In the regeneration study, the absorption capacity after regeneration was reduced by approximately 7% for all ionic liquids, in which the anion was sulfite-based, showing excellent regeneration. Ethyl sulfite showed the highest absorption capacity of CO2 among the ionic liquids based on the sulfite anion. In particular, the absorption capacity of [beim] ethyl sulfite was 1.1 mol CO2 / mol IL at an absorption equilibrium pressure of 22 bar. In the regeneration study, the absorption capacity after regeneration was reduced by approximately 7% for all ionic liquids, in which the anion was sulfite-based, from which regeneration is outstanding. After the absorption experiment, the viscosity of the sample tended to decrease by approximately 8% compared to that before the absorption experiment. On the other hand, the absorbent was synthesized in the first step. Moreover, the raw material used is also inexpensive and has excellent reproducibility and highly stable absorbent capacity.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.89-94
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• 2021

The mechanical reliability of flexible devices has become a major concern on their commercialization, where the importance of reliable bonding is highlighted. In terms of component materials' properties, it is important to consider thermal damage of polymer substrates that occupy large area of the flexible device. Therefore, room temperature bonding process is highly advantageous for implementing flexible device assemblies with mechanical reliability. Conventional epoxy resins for the bonding still require curing at high temperatures. Even after the curing procedure, the bonding joint loses flexibility and exhibits poor fatigue durability. To solve this problems, low-temperature and adhesive-free bonding are required. In this work, we develop a room temperature bonding process for polymer substrates using carbon nanotube heated by microwave irradiations. After depositing multiple-wall carbon nanotubes (MWNTs) on PET polymer substrates, they are heated locally with by microwave while the entire bonding specimen maintains room temperature and the heating induces mechanical entanglement of CNT-PET. The room temperature bonding was conducted for a PET/CNT/PET specimen at 600 watt of microwave power for 10 seconds. Thickness of the CNT bonding joint was very thin that it obtains flexibility as well. In order to evaluate the mechanical reliability of the joint specimen, we performed lap shear test, three-point bending test, and dynamic bending test, and confirmed excellent joint strength, flexibility, and bending durability from each test.

• Journal of Life Science
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• v.31 no.6
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• pp.568-573
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• 2021

This study identified genomic factors associated with endoplasmic reticulum protein (ERp)29 gene expression in a genome-wide association study (GWAS) of genetic variants, including single-nucleotide polymorphisms (SNPs). In total, 373 European genes from the 1000 Genomes Project were analyzed. SNPs with an allelic frequency of less than or more than 5% were removed, resulting in 5,913,563 SNPs including in the analysis. The following expression quantitative trait loci (eQTL) from the long noncoding RNA LOC105372577 were strongly associated with ERp29 expression: rs6138266 (p<4.172e10), rs62193420 (p<1.173e10), and rs6138267 (p<2.041e10). These were strongly expressed in the testis and in the brain. The three eQTL were identified through a transcriptome-wide association study (TWAS) and showed a significant association with ERp29 and osteosarcoma amplified 9 (OS9) expression. Upstream sequences of rs6138266 were recognized by ChIP-seq data, while HaploReg was used to demonstrate how its regulatory DNA binds upstream of transcription factor 1 (USF1). There were no changes in the expression of OS9 or USF1 following ER stress.

• Journal of the Korean Geosynthetics Society
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• v.21 no.4
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• pp.1-12
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• 2022

Generally, the plate load test and the field density test are conducted for compaction quality control in earthwork, and then additional analysis. Recently developed that the DCPT (Dynamic Cone Penetration Test) equipment for smart compaction quality control its the system are able to get location and real-time information about worker history management. The IoT-based the DCPT system improved the time-cost in the field compared traditional test, and the functions recording and storage of the DPI (Dynamic Cone Penetration Index) were automated. This paper describes using these DCPT equipment on in-situ and compared to the standards of the DCPT, and the compaction trend had be confirmed with DPI as the field test data. As a result, the DPI of the final compaction decreased by 1.4 times compared to the initial compaction, confirming the increase in the compaction strength of the subgrade compaction layer 10 to 14 cm deep from the surface. A trend of increasing compaction strength was observed. This showed a tendency to increase the compaction strength of the target DPI proposed by MnDOT and the results of the existing plate load test, but there was a difference in the increase rate. Therefore, additional studies are needed on domestic compaction materials and laboratory conditions for target DPI and correlation studies with the plate load tests. If this is reflected, it is suggested that DCPT will be widely used as smart construction equipment in earthworks.

• Applied Chemistry for Engineering
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• v.34 no.1
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• pp.23-29
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• 2023

Microfluidic reactors have been made to achieve significant development for the generation of new functional materials to apply in a variety of fields. Over the last decade, microfluidic reactors have attracted attention as a user-friendly approach that is enabled to control physicochemical parameters such as size, shape, composition, and surface property. Here, we develop a centrifugal microfluidic reactor that can control the flow of fluid based on centrifugal force and generate multifunctional particles of various sizes and compositions. A centrifugal microfluidic reactor is fabricated by combining microneedles, micro- centrifuge tubes, and conical tubes, which are easily obtained in the laboratory. Depending on the experimental control param- eters, including centrifuge rotation speed, alginate concentration, calcium ion concentration, and distance from the needle to the calcium aqueous solution, this strategy not only enables the generation of size-controlled microparticles in a simple and reproducible manner but also achieves scalable production without the use of complicated skills or advanced equipment. Therefore, we believe that this simple strategy could serve as an on-demand platform for a wide range of industrial and academic applications, particularly for the development of advanced smart materials with new functionalities in biomedical engineering.

• Journal of the Korean Geotechnical Society
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• v.38 no.12
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• pp.19-28
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• 2022

Cavities behind concrete walls can adversely affect the stability of structures. Thus study aims to detect cavities behind concrete structures using a microphone in a laboratory model test. A small-scale concrete wall is constructed in a chamber, which is composed of a reinforced concrete plate and dry soil. A plastic bowl is then placed between the plate and soil to simulate a cavity behind the concrete structure. Leaky surface acoustic waves are generated by impacting the concrete plate using a hammer and are measured using a microphone. The measured signals are analyzed using natural frequencies, and cavity-free sections are evaluated. The test results show that the first natural frequency decreases at the cavity section due to the flexural vibration behavior of the plate. In addition, the amplitude corresponding to the first natural frequency decreases as the measurement location becomes farther from the cavity center and significantly decreases at the measurement locations near the rebars. This study demonstrates that a microphone may be useful to detect cavities behind concrete walls.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.1
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• pp.78-88
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• 2022

Objectives: To develop the smart sensor to protect worker's health from chemical exposure by adopting ICT (Information and Communications Technology) technologies. Methods: To develope real-time chemical exposure monitoring system, IoT (Internet of Things) sensor technology and regulations were reviewed. We developed and produced smart sensor. A smart sensor is a system consisting of a sensor unit, a communication unit, and a platform. To verify the performance of smart sensors, each sensor has been certified by the Korea Laboratory Accreditation Scheme (KOLAS). Results: Chemicals (TVOC; Total Volatile Organic Compounds, Cl₂: Chlorine, HF: Hydrogen fluoride and HCN: Hydrogen cyanide) were selected according to a priority logic (KOSHA Alert, acute poisoning statistics, literature review). Notifications were set according to OEL (occupational exposure limit). Sensors were selected based on OEL and the capabilities of the sensors. Communication is designed to use LTE (Long Term Evolution) and Wi-Fi at the same time for convenience. Electronic platform were applied to build this monitoring system. Conclusions: Real-time monitoring system for OEL of hazardous chemicals in workplace was developed. Smart sensor can detect chemicals to complement monitoring of traditional workplace environmental monitoring such as short term and peak exposure. Further research is needed to expand the scope of application, improve reliability, and systematically application.

• Journal of Korea Entertainment Industry Association
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• v.15 no.8
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• pp.279-290
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• 2021

As the university's academic management was not carried out smoothly due to COVID-19, and most of them were conducted as non-face-to-face classes, students' dropout is steadily increasing. In this study focus group interviews were conducted to analyze physics students and professors' recognition of the COVID-19 non-face-to-face class environment. Based on the results, the implications of non-face-to-face classes for physics education were presented. Physics students described their feelings about un-tact teaching as 'the class in which the body is comfortable but the mind is uncomfortable', 'a person who is smarter than me seems to explain a book, reading it' and 'a short clip lecture which may be comfortable but cause losses to me', while the professors also described them as 'a fully transformed class system' and 'a online class putting much burden on me'. Regarding school dropout, students said that the concerns about dropout during non-face-to-face classes were deepened about transfer or transfer. The professors said that the department atmosphere had lost vitality due to the increase in non-face-to-face classes and academic dropouts, and had a lot of worries because of the recruitment rate and external university evaluation. The implications of the COVID-19 non-face-to-face class situation for physics education suggest that it is required to strengthen the interaction between professors and students, finding ways to enhance the sense of reality to supplement laboratory classes and giving opportunities to professors to share their pedagogical contents knowledge in physics.