• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.120-127
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• 2022

Nitrogen oxide(NOx) is a major cause of air pollution, exists in the form of nitrogen monoxide and nitrogen dioxide, and is harmful to the human body. Recently, a number of studies to reduce NOx in the atmosphere have been conducted, and these efforts have been the same in the field of construction materials. It is known that NOx can be efficiently removed by using a photocatalytic reaction. In this study, the NOx removal performance of the foam composite using activated carbon(AC) and titanium dioxide(TiO₂) was investigated. AC was used to enhance the photocatalytic reaction of TiO₂ by increasing the internal specific surface area of the foam composite. In this study, foam composites were prepared using the substitution rate of AC as the main variable. The NOx removal performance of specimen was evaluated according to the test method presented in ISO-22197-1. The specific surface area of the foam composite showed a tendency to increase according to the AC content, but decreased at 15% or more. Also, when the AC substitution rate was 15%, the NOx removal efficiency was the highest.

• Journal of the Korean Institute of Gas
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• v.27 no.1
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• pp.63-69
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• 2023

Although Korea is the world's No. 1 semiconductor producing country, most studies are conducted with risk assessment for simple material risks due to the closedness of the site for industrial protection. In terms of industrial safety, a monitoring system such as a gas detector to determine the leakage of hazardous substances has been established, but research on effectively discharging harmful gastritis substances in case of leakage has only recently begun. Semiconductor manufacturing facilities (gas boxes) where a large amount of flammable materials are handled are currently being safety managed by using a gas detector and blocking the air inlet. It is difficult to dilute in a short time in case of leakage of flammable substances. Therefore, in this study, based on various criteria, the size of the duct according to the size of the gas box is determined and the appropriate size of the air inlet is studied to minimize the exhaust performance requirement without exposing hazardous chemicals to the outside in the event of a flammable leak. We want to do an optimal exhaust design.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.217-218
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• 2021

With the prolonged Covid-19 epidemic, movement restrictions such as social distancing are prolonged, and as people stay indoors for a longer time, interest in indoor air pollution is increasing. Indoor air quality is not easily purified unlike outdoors. Among indoor building materials, paints and flooring contain formaldehyde that causes sick house syndrome and VOCs that contain carcinogenicity and harmfulness. For modern people who spend a lot of time living indoors for more than an hour, the occurrence of these harmful substances can be said to be fatal. In response to these risks, in July 2019, the government reinforced the standards for indoor air quality to protect the public's health by raising the detection standards for fine dust, ultrafine dust, and formaldehyde in indoor multi-use facilities. People use machines such as air purifiers to improve indoor air quality, or make efforts such as periodic ventilation. In order to reduce or support these other ancillary efforts more effectively, to reduce the generation of pollutants in the building itself, or to adsorb or purify pollutants in the air, use carbon black as an admixture to make a cement hardened body, and to grasp basic physical properties and adsorption capacity. And the result is as follows. As a result of the experiment to determine the appropriate amount of carbon black, it was confirmed that the more the amount of carbon black was added, the better it was in the formaldehyde emission test, but the tendency was not clear when measuring the flexural strength, so a further experiment to improve this is needed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1A
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• pp.101-108
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• 2009

The performance of high-early strength pavement concrete for large areas is influenced by the physical and chemical environment during service life. Generally, penetration, diffusion, and absorption of harmful materials that exist outside the concrete cause damage to its structure. Thus, we have to use a mixture for durability to keep the required quality for the planned service life. Moreover, in using high-early-strength cement and accelerators, a high heat of hydration to create the initial strength can cause cracks. Based on evaluations from optimal mix proportions of high-early-strength pavement concrete for large areas, we conducted water permeability, abrasion resistance, freeze-thaw, plastic, drying, and autogenous shrinkage tests. Test result showed that a mix of accelerator and PVA fibers showed excellent performance.

• The Journal of the Acoustical Society of Korea
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• v.26 no.1
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• pp.32-41
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• 2007

The control room has been usually designed by the consideration of only one listening position for the sound engineer. By this study. many listening positions with the very similar acoustical condition were located in the specific region, so-called 'the reflection free zone', where the several engineer could evaluate the quality of sound at the same time. For constructing the reflection free zone, the control room has been designed by the concept of the $LEDE^{TM}$, and the initial time delay gap has been controled by the structure of control room and the properties of sound-absorbing materials. diffuser, Helmholtz resonator and image source of sound. The occurrence of any harmful phenomena like the standing wave, acoustic focusing. coloring. Hass effect and flutter echo, has greatly reduced in the reflection free zone.

• Journal of Mushroom
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• v.22 no.1
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• pp.17-21
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• 2024

Mushroom-based vegan meat has thus far been used as a food for humans instead of pets. However, based on its texture and nutritional content, it is considered suitable for processing into pet treats. In the present study, we developed a prototype dog chew with a sweetening coating added to a fungal mycelium mat obtained by culturing the Basidiomycetous fungus Trametes orientalis. The palatable coating applied to the mycelium mat by plasticizing the mat with glycerol improved the taste and aroma of the existing mat, and the dog consumed it without difficulty. Future improvements may include a softening process to reduce the chewiness level and a procedure to reduce the crude fiber content. Mycelium-mat-based dog chews, manufactured using eco-friendly materials and processes that are not harmful to the environment are expected to enter the market as eco-friendly alternatives to conventional pet treats. Controlling their physical properties require further study.

• Journal of dental hygiene science
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• v.3 no.2
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• pp.59-66
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• 2003

As a basic research material to make more efficient healthcare and health promotion for dental hygienists, this study intends to determine which factors may affect their awareness of occupational diseases. For this sake, this study attempted to investigate into a variety of literatures and data, and applied a questionnaire survey to 160 dental hygienists for about 5 months(from June to October 2003), who were all employed in domestic dental clinics or offices. As a result of analysis, this study can be concluded as follows: (1) The result of analyzing how dental hygienists recognized their occupational diseases showed that 'stiffness in muscle, neck or shoulder due to intensive use of specific physical regions' and 'stress resulting from the attributes of each task' reached the highest awareness(90.6%) of all, which was followed by 'lower eyesight due to detailed or even sophisticated tasks for many hours(65%)' and 'symptoms of ruptured disk due to standing tasks as dental hygienists do for many hours(62.5%).' (2) The result of analyzing how dental hygienists recognize their occupational diseases showed that their awareness averaged 7.28 points out of 14 points, which implies that their awareness of occupational diseases is not very high. Meanwhile, the result of examining how they recognize detrimental or harmful properties of given materials against human body showed that a majority of total respondents(74.4%) regarded given materials as detrimental to human body. (3) The result of examining how dental hygienists recognize their occupational diseases showed that a majority of total respondents(91.9%) identified their own occupational diseases. Many of total respondents(41.9%) pointed out that environmental improvement around workshop in each clinic or office should be foremost prerequisite to health and welfare for dental hygienists. Next, 34.4% of total respondents pointed out the necessity to perform in-house health diagnosis and examination on a regular basis, and 13.1% of total respondents thought it necessary to carry on healthcare education into harmful properties in the aspect of dental materiology, respectively.

• Journal of dental hygiene science
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• v.13 no.1
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• pp.97-104
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• 2013

This study investigated the safety management behavior of dental professionals to minimize exposure to harmful elements of amalgam and resin. As for the use of amalgam and resin, 85.8% of them used amalgam. 100% of used composite resin 100%. 97.8% used acryl resin, and 95.7% used tray resin. 95.2% and 36.5% of them were aware of the harm of amalgam and resin respectively. When using resin, their safety management behavior score was 1.99 on average, and the lowest score was 2.50 on average for 'ventilate the indoor air when handling resin'. Their average score of the safety management behavior was 1.83 when using amalgam. The lowest score was 2.89 on average for 'use the rubber dam for patients when handling amalgam'. As a result of the safety management behavior based on general characteristics, all characteristics were significant with regard to amalgam, and my position at work and work experience were significant with regard to resin (p<0.05). The correlation between the safety management behavior and general characteristics was analyzed when dental amalgam and resin are used. Amalgam was statistically correlated with academic background (p<0.05) and position at work (p<0.05), whereas resin was statistically significantly correlated with age (p<0.05) and position at work (p<0.05). Accordingly, education about the harm of dental materials must be continuously provided for dental professionals when they handle dental materials so that safety management behavior will be conducted correctly, and active efforts to protect the health of dental professionals from harmful chemicals must be made.

• Journal of the Korean GEO-environmental Society
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• v.13 no.1
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• pp.45-51
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• 2012

This article aims to find method to mix a harmless hardening agent and soil generated during construction to make paving materials. The main purpose of this research is to get rid of the harmfulness(Chromium (VI), etc.) of cement which has been generally and frequently used as a hardening agent and strengthen it so that it can be used for the general foundation solidification and stabilization of civil engineering/construction structures such as dredging soil treatment, marine structure foundation treatment, surface soil stabilization, and river bank erosion prevention. NSS(Natural Stabilizer Soil) used for this study takes as its chief ingredient the mixture of lime and staple fibers extracted from natural fibers. It increases the shearing strength of soil that it improves the support and durability of the foundation and prevents flooding and frost as well. The pH measured to know its eco-friendliness was 6.67~7.15, and according to the migration testing, only Pb and CN were lower than the standards, so it can be said that NSS has almost no harmful components in it. According to the result of uniaxial strength testing, when the mixture ratio of weathered soil to NSS was 6%, about 1,850kpa strength was expressed. And according to the result of CBR. testing to figure out its appropriateness as a paving material, the CBR of the foundation was 4%~6%. But when the mixture ratio of NSS is over 6%, the water immersion CBR. is over 100%; thus, it is expected that it will show great utility as a paving material.

• Journal of Chest Surgery
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• v.45 no.6
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• pp.380-389
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• 2012

Background: Bovine pericardium is one of the most widely used materials in bioprosthetic heart valves. Immunologic responses have been implicated as potential causes of limited durability of xenogenic valves. This study aimed to determine the effectiveness of decellularization and ${\alpha}$-galactosidase (${\alpha}$-gal) to remove major xenoreactive antigens from xenogenic tissues. Materials and Methods: Recombinant Bacteroides thetaiotaomicron (B. thetaiotaomicron) ${\alpha}$-gal or decellularization, or both were used to remove ${\alpha}$-gal from bovine pericardium. It was confirmed by ${\alpha}$-gal-bovine serum albumin-based enzyme-linked immunosorbent assay (ELISA), high-performance anion exchange chromatography, flow cytometry, 3,3'-diaminobenzidine-staining, and lectin-based ELISA. The mechanical properties of bovine pericardium after decellularization or ${\alpha}$-gal treatment were investigated by tests of tensile-strength, permeability, and compliance. Collagen fiber rearrangement was also evaluated by a 20,000${\times}$ transmission electron microscope (TEM). Results: Recombinant B. thetaiotaomicron ${\alpha}$-gal could effectively remove ${\alpha}$-gal from bovine pericardium B. thetaiotaomicron (0.1 U/mL, pH 7.2) while recombinant human ${\alpha}$-gal removed it recombinant human ${\alpha}$-gal (10 U/mL, pH 5.0). There was no difference in the mechanical properties of fresh and recombinant ${\alpha}$-gal-treated bovine pericardium. Furthermore, the TEM findings demonstrated that recombinant ${\alpha}$-gal made no difference in the arrangement of collagen fiber bundles with decellularization. Conclusion: Recombinant B. thetaiotaomicron ${\alpha}$-gal effectively removed ${\alpha}$-gal from bovine pericardium with a small amount under physiological conditions compared to human recombinant ${\alpha}$-gal, which may alleviate the harmful xenoreactive immunologic responses of ${\alpha}$-gal. Recombinant ${\alpha}$-gal treatment had no adverse effects on the mechanical properties of bovine pericardium.