1,530 research outputs found

    New-type of Multi-purpose Standard Radon Chamber in South Korea

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    Radon is an inert and a radioactive gas which is colorless, tasteless and odorless. As the radon decay proceeds, and if DNA damage continues beyond repair capacity of cells in the human body, it can cause severe health problems such as lung cancer in the long-term. There is a tendency that those countries where legal restriction on radon is strict, various studies related to radon are under way. In South Korea, radon has been regulated under recommendation level. Even though there are about 3 standard radon chambers in Korea, they have not been in an active use because of lack of demand. Also, most of them are specialized in calibration of radon detectors only. Recently, Korean government started giving some attention to radon issue and supporting radon research fields. Thus, this study was carried out to develop a new type of radon chamber for multi-purpose such as 1) radon emission rate from natural and artificial radon sources; 2) calibration of radon detectors; 3) evaluation of radon mitigation efficiency. Keywords: Radon, Radon Chamber, Indoor Air Quality, Chamber Desig

    Properties of Magnesia Composites According to Replacement Ratio of Perlite

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    Recently, passive and zero-energy construction has increased in Korea due to the government`s continuous application of budget-conscious policies for establishments. Accordingly, construction materials are being advanced, and the required performance standards for insulation materials are increasing. However, problems such as fire vulnerability and degradation of physical properties for organic and inorganic insulation materials are shown, so it is necessary to solve this problem. The objective of this research is to examine the properties of the composites by analyzing the flexural breaking load, impact resistance, density, VOCs concentration reduction rate, and fine dust concentration reduction rate of the composites manufactured based on the perlite substitution rate of the magnesia composites. The flexural breaking load test of the composites was assessed according to ‘KS F 3504’, a gypsum board standard and the impact resistance was assessed according to ‘KS F 4715’. The performance evaluation of adsorption performance of air pollutants of the VOCs and fine dust in the context of the small chamber technique suggested by Hanbat University. The results of this study are as follows: The flexural breaking load according to the perlite replacement rate tended to decrease as the perlite replacement rate increased. It is determined that the flexural breaking load is reduced by generating a large amount of pores inside due to the perlite porous structure characteristics. In the case of impact resistance, the impact resistance tended to increase as the perlite displacement rate increased. It is determined that the volume of the binder in the board is reduced, and pores inside the board are generated due to perlite, which is a porous material, thereby reducing the overall bonding force of the board. In the case of VOCs and fine dust concentrations, the VOCs and fine dust concentration reduction rates tended to increase as the perlite replacement rate increased. In the case of the perlite displace rate of 30%, the VOCs concentration decreased by 82.6%, and the fine dust concentration decreased by 87.9%. It has been established that the porous properties of perlite used to create a huge number of pores in the hardened body cause the concentration to be lowered physically through adsorption. This study\u27s findings are thought to be fundamental information for securing the engineering properties and air pollution absorption of magnesia composites blended with perlite

    Anxiety Control and Periodontal Practice

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    Chronic periodontitis is one of the most common diseases in clinical dentistry, which requires various surgical interventions to treat the moderately to severely destructed supporting periodontium. Most patients have anxiety and fear to those surgical procedures and dentists often have problems dealing with those patients. By applying the conscious sedation technique in outpatient units, periodontists have become able to manage their patients successfully with less anxiety or fear. Also, we have experienced the increased level of patients\u27 satisfaction. Generally, periodontal treatments are time consuming procedures and patients are usually reluctant to the periodontal instruments. This study is focused on the sedation procedure with intravenous midazolam infusion performed in Department of Periodontology of Ewha Womans University Hospital. Using questionnaires, we evaluated 80 randomly selected patients for the anxiolytic effect of intravenous midazolam. Anxiety control using IV sedation was very helpful in performing various periodontal reconstructive and advanced surgical procedures in implant dentistry

    Development of Automatic Mold Shot Measurement and Management System for Smart Factory

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    Many small- and medium-sized car-part manufacturers are either still managing their mold manually or rarely managing it, and therefore, experience significant manufacturing cost and loss in time. In such a situation, a module has been developed in the present work which can count the number of mold used. Such a module is extremely important for small and medium-sized enterprises (SMEs) applying which in the production line they will be able to manage the mold life cycle and improve product quality. This is expected to have both direct and indirect effects on their business activities. The developed system uses a photo sensor, distance measurement sensor, Atmega128 MCU, tablet pc and Bluetooth communication module. The actual module developed in this study was set up on a molding equipment for test and data were collected using an existing tablet PC. The test showed that the number of shots increased when the upper mold touched the lower mold. The maximum and minimum value between the upper and lower molds could be adjusted with the automatic mold shot measurement and management system. Therefore, any molding equipment with various upper-lower gaps will be able to apply the newly developed system

    The Effect of Ca-P Coated Bovine Bone Mineral on Bone Regeneration around Dental Implant in Dogs

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    There are many obstacles to overcome in implant dentistry. The bony defect around implant can be seen in immediate installation procedures. Following tooth extraction, however, a socket often presents dimensions that may be considerably greater than the dimensions of a conventional implant

    Shuttle-effect-free sodium–sulfur batteries derived from a Tröger's base polymer of intrinsic microporosity

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    Room-temperature sodium-sulfur (RT Na-S) batteries have recently gained attention as next-generation energy storage devices owing to their low cost, the abundance of sodium, and the high theoretical capacity of sulfur. However, the notorious shuttle effect, caused by the dissolution of intermediate polysulfides during cycling, limits the long-term performance of Na-S batteries. In this study, intrinsically microporous Tro center dot ger's base based polymer (PIM-EA-TB)-based carbon-sulfur composites are prepared for shuttle-effect-free RT Na-S batteries by utilizing the combination of physical confinement and covalent bonding in a single material. The composites demonstrate excellent electrochemical performance, including a negligible capacity fading over 350 cycles and a high coulombic efficiency of approximately greater than 99%.

    A mirror for lab-based quasi-monochromatic parallel x-rays

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    A multilayered parabolic mirror with six W/Al bilayers was designed and fabricated to generate monochromatic parallel x-rays using a lab-based x-ray source. Using this mirror, curved bright bands were obtained in x-ray images as reflected x-rays. The parallelism of the reflected x-rays was investigated using the shape of the bands. The intensity and monochromatic characteristics of the reflected x-rays were evaluated through measurements of the x-ray spectra in the band. High intensity, nearly monochromatic, and parallel x-rays, which can be used for high resolution x-ray microscopes and local radiation therapy systems, were obtained.open0

    Experimental Study on the Acellular Demal Matrix Graft for the Root Coverage in Dog

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    Mucogingival surgery is a plastic surgical procedure designed to correct defects in the morphology, position, and dimensions of the gingiva surrounding the teeth. Many surgical techniques have been reported in mucogingival surgery. Since these procedures also include the soft tissue esthetic approach, the term periodontal plastic surgery has been proposed to be more appropriate.1 Root coverage is a procedure that falls with this definition, and it has attracted more interest than others

    Genetic evaluation of domestic walnut cultivars trading on Korean tree markets using microsatellite markers

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    Walnut (Juglans regia L.) is regarded as a healthy food because of its high nutritional composition and various health benefits. Although several walnut cultivars are being actively traded for domestic plantation or ornament in Korea, no particular effort has been made to evaluate genetic quality management of walnut cultivars in domestic tree markets. In this study, as an effort to evaluate the status of walnut seedling trade, we collected walnut seedlings of diverse cultivars from domestic tree markets and several locations in Korea and performed genotype analysis for the collections using microsatellite markers (76 individuals belonging to eight domestic cultivars). We used 12 markers that were previously reported to be informative and polymorphic in walnuts. The number of alleles that was detected from the collections using these markers ranged from 6 to 16, with heterozygosity values ranging from 0.03 to 0.75. Dendrogram revealed that the domestic walnut cultivars trading on tree markets could be genotypically distinguished from various foreign cultivars. However, genotyping data also showed that individual plants belonging to identical cultivars were sporadically distributed on the dendrogram, indicating that walnut cultivars trading on domestic tree markets seem to be poorly managed.Keywords: Walnut (Juglans regia L.), microsatellite markers, tree market, seedling trade, domestic cultivars, foreign cultivars, cultivar managementAfrican Journal of Biotechnology Vol. 11(29), pp. 7366-7374, 10 April, 201

    Inappropriate antidiuretic hormone syndrome presenting as ectopic antidiuretic hormone-secreting gastric adenocarcinoma: a case report

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    INTRODUCTION: Although the syndrome of inappropriate antidiuretic hormone has connection with various malignant tumors, there are few reports associated with advanced gastric cancer. CASE PRESENTATION: We describe the case of a 63-year-old Korean male with inappropriate antidiuretic hormone syndrome due to an ectopic antidiuretic hormone-producing advanced gastric adenocarcinoma manifested with overt serum hypo-osmolar hyponatremia and high urinary sodium concentrations. His adrenal, thyroidal, and renal functioning were normal, and the hyponatremia improved following removal of the tumor. The cancer cells were immunostained and found to be positive for the antidiuretic hormone. To our knowledge, this is the first report of an antidiuretic hormone-secreting advanced gastric adenocarcinoma associated with the syndrome of inappropriate antidiuretic hormone, showing cancer cells immunostained for the antidiuretic hormone. CONCLUSIONS: Although a strong relationship between gastric cancer and the syndrome of inappropriate antidiuretic hormone remains to be established, we suggest that gastric cancer could be included as a differential diagnosis of cancer that is associated with the syndrome of antidiuretic hormone
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