• Electronics and Telecommunications Trends
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• v.34 no.5
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• pp.1-13
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• 2019

In modern times, X-ray imaging has become a necessary tool for early diagnosis, quality control, nondestructive testing, and security screening. X-ray imaging equipment generally comprises an X-ray generator and an image sensor. Most commercially available X-ray generators employ filament-thermionic electron-based X-ray tubes, thus demonstrating typical analog behavior, such as slow response and large stray X-rays. Furthermore, digital X-ray sources, which have been studied extensively using field electron emitters manufactured from nanometer-scale materials, provide fast and accurately controlled ultra-shot X-rays. This could usher in a new era of X-ray imaging in medical diagnosis and nondestructive inspections. Specifically, digital X-ray sources, with reduced X-ray dose, can significantly improve the temporal and spatial resolution of fluoroscopy and computed tomography. Recently, digital X-ray tube technologies based on carbon nanotubes, developed by Electronics and Telecommunications Research Institute, have been transferred to several companies and commercialized for dental imaging for the first time.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.46-52
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• 2019

This research was conducted to analyze the effects of temperature on coking characteristics of kerosene. The kerosene was heated to 600 K, 700 K, and 800 K, and the cooled samples were collected. The used copper tubes were replaced according to the temperature conditions. The liquid and copper specimens were analyzed by gas chromatography-mass spectrometry and scanning electron microscopy equipped with an energy dispersive x-ray spectrometer, respectively. The results of the analysis confirmed that a carbon deposit was formed from the coking of fuel on the inner surface of the copper specimen at a relatively high temperature (800 K) of the copper tube.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.14 no.4
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• pp.35-42
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• 2018

Among the various ground source heat pump systems, vertical-type heat pump systems have been distributed greatly. Most of the vertical-type ground source heat pump systems have been designed based on the Korean Ministry of Knowledge Economy Announcement in Korea. In this study, the design process of the vertical-type ground source heat pump system in the announcement was analyzed, and the effects of the design parameters on the ground loop heat exchanger were investigated. Borehole thermal conductivity was the highest dominant design parameter for ground loop heat exchangers. The borehole thermal conductivity was changed according to the pipe and grout thermal conductivity. For optimal design of the ground heat pump system, it is highly recommended that the design process in the announcement will be revised to adopt the various tubes and grout which have higher thermal conductivity. In addition, the certification standard for heat pump unit should be revised to develop the heat pump with a small flow rate.

• The Korean Journal of Emergency Medical Services
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• v.23 no.1
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• pp.87-99
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• 2019

Purpose: The aim of this study was conducted to assess the proficiency of both direct laryngoscopy and video laryngoscopy and the usefulness of each laryngoscope, thereby provide basic data for further education using video laryngoscopy. Methods: Forty one paramedic subjects participated in this study. Usability was measured with the System usability scale. The Macintosh direct laryngoscope and $C-MAC^{(R)}$ video laryngoscope were two instruments evaluated in the study. Results: Training with video laryngoscopy showed significantly better results within the categories of dental injury (p=.004), esophageal intubation (p=.001), and proper depth placement of intubation tubes (p=.019). The results of the System usability scale questionnaire and the degrees of visibility based on the Cormack & Lehane classification were also found to be better achieved with the video laryngoscopy (p=.000). Conclusion: This study suggests enhancing education with video laryngoscopy, which could reduce the risk of complications and duration of intubation while increasing the success rate among students and emergency medical technicians with little experience, rather than the existing method of only using direct laryngoscope, which requires considerable experience and skills.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.54.1-54.1
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• 2019

Solar observations often show that interaction of more than one flux rope is involved in solar eruptions. In this regard, Lau and Finn (1996) intensively studied the interaction of two flux ropes, which reside in between two parallel planes each mimicking one polarity region of the solar photosphere. However, this geometry is quite far from the real solar situation, in which all feet of flux tubes are rooted in one surface only. In this paper, we study the interaction of two flux ropes in a semi-infinite region above a plane representing the solar photosphere. Four cases of the flux rope interaction are investigated in our MHD simulation study: (1) parallel axial fields and parallel axial currents (co-helicity), (2) antiparallel axial fields and parallel axial currents (counter-helicity), (3) parallel axial fields and antiparallel axial currents (counter-helicity), and (4) antiparallel axial fields and antiparallel axial currents (co-helicity). Each case consists of four or six subcases according to the background field direction relative to the flux ropes and the relative positions of the flux rope footpoints. In our simulations, all the cases eventually show eruptive behaviors, but their degree of explosiveness and field topological evolutions are quite different. We construct artificial emission measure maps based on the simulations and compare them with images of CME observations, which provides us with information on what field configurations may generate certain eruption features.

• Child Health Nursing Research
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• v.25 no.2
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• pp.133-142
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• 2019

Purpose: This prospective study was conducted to determine the incidence and related characteristics of respiratory medical device-related pressure ulcers (MDRPU) in children admitted to a pediatric intensive care unit (PICU). Methods: The participants were 184 children who were admitted to the PICU of P University Hospital from April 2016 to January 2017. Data were collected on the occurrence of respiratory MDRPU and characteristics regarding the application of respiratory medical devices. Results: Respiratory MDRPU occurred in 11.9% of participants (58.3%: stage I ulcers, 37.5%: mucosal ulcers). The devices associated with respiratory MDRPU were endotracheal tubes (54.2%), high-flow nasal cannulas (37.5%), and oximetry probes (8.3%). Respiratory MDRPU associated with an endotracheal tube were significant differences according to the site and strength of fixation, the use of a bite block and adhesive tape, skin dryness, and edema. In high-flow nasal cannulas, significant differences were found according to the site of fixation, immobility after fixation, and skin dryness. Conclusion: The occurrence of respiratory MDRPU is significantly affected by the method and strength of fixation, as well as skin dryness and edema. Therefore, appropriate consideration of these factors in nursing care can help prevent respiratory MDRPU.

• Composites Research
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• v.32 no.5
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• pp.211-215
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• 2019

The cell culture process under in vitro condition is much different from the actual human body environment. Therefore, in order to precisely simulate the human body environment, a dynamic cell culture device capable of delivering mechanical stimulation to cells is essential. However, conventional dynamic cell culture devices require relatively complicated devices such as tubes, pumps, and motors, and the mechanical stimuli delivered is also simple. In this study, an electro-active polymer actuator as a driving component is introduced to design simply driven dynamic cell culture device without complicated components. The device is capable of delivering relatively complex mechanical stimuli to the cells.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.4
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• pp.465-479
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• 2020

Two waste forms, namely cement and geopolymer, were investigated and tested in this study to solidify the corrosive sludge generated from the surface and precipitates of the tubes of steam generators in nuclear power plants. The compressive strength of the cement waste form cured for 28 days was inversely proportional to waste loading (24.4 MPa for 0wt% to 2.7 MPa for 60wt%). The corrosive sludge absorbed the free water in the hydration reaction to decrease the cementation reaction. When the corrosive sludge waste loading increased to 60wt%, the cement waste form showed decreased compressive strength (2.7 MPa), which did not satisfy the acceptance criteria of the repository (3.45 MPa). Meanwhile, the compressive strength of the geopolymer waste form cured for 7 days was proportional to waste loading (23.6 MPa for 0wt% to 31.9 MPa for 40wt%). The corrosive sludge absorbed the free water in the geopolymer when the water content decreased, such that a compact geopolymer structure could be obtained. Consequently, the geopolymer waste forms generally showed higher compressive strengths than cement waste forms.

• Journal of the Korean Society of Radiology
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• v.79 no.6
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• pp.337-339
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• 2018

Parovarian cyst is usually simple cyst, and accounts for 10%-20% of adnexal masses. Borderline or malignant parovarian tumor is rare, and it contains papillary projection at the smooth inner wall. We report the ultrasonography, CT and MRI findings of a parovarian serous borderline tumor in 19-year-old female presenting left lower quadrant abdominal discomfort for 2 days.

• International journal of steel structures
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• v.18 no.5
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• pp.1577-1588
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• 2018

As the excellent mechanical performance and easy construction of concrete filled steel tubes (CFST) composite structure, it has the potential to be used to strengthen RC pier columns. Therefore, tests were conducted on 2 reinforcement concrete (RC) stub columns and 9 RC columns strengthened with circular CFST under axial loading. The test results show that the circular CFST strengthening method is effective since the mean bearing capacity of the RC columns is increased at least 3.69 times and the ductility index is significantly improved more than 30%. One of the reasons for enhancement is obvious confinement provided by steel tube besides the additional bearing capacity supplied by the strengthening materials. From the analysis of the enhancement ratio, the strengthening structure has at least an extra 20% amplification except for taking full advantage of the strength of the strengthening material. Through the analysis of confining stress provided by steel tube and the stress-strain relationship of confined concrete, it is found that the strength of the core concrete can be increased by 21-33% and the ultimate strain can be enhanced to beyond $15,000{\mu}{\varepsilon}$.