• Journal of the Korean Society of Radiology
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• v.15 no.4
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• pp.455-461
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• 2021

Cardiomegaly is one of the most common diseases seen on chest X-rays, but if it is not detected early, it can cause serious complications. In view of this, in recent years, many researches on image analysis in which deep learning algorithms using artificial intelligence are applied to medical care have been conducted with the development of various science and technology fields. In this paper, we would like to evaluate whether the Inception V3 deep learning model is a useful model for the classification of Cardiomegaly using chest X-ray images. For the images used, a total of 1026 chest X-ray images of patients diagnosed with normal heart and those diagnosed with Cardiomegaly in Kyungpook National University Hospital were used. As a result of the experiment, the classification accuracy and loss of the Inception V3 deep learning model according to the presence or absence of Cardiomegaly were 96.0% and 0.22%, respectively. From the research results, it was found that the Inception V3 deep learning model is an excellent deep learning model for feature extraction and classification of chest image data. The Inception V3 deep learning model is considered to be a useful deep learning model for classification of chest diseases, and if such excellent research results are obtained by conducting research using a little more variety of medical image data, I think it will be great help for doctor's diagnosis in future.

• Journal of Electrochemical Science and Technology
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• v.9 no.1
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• pp.60-68
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• 2018

In aqueous rechargeable lithium ion batteries, $LiV_3O_8$ exhibits obviously enhanced electrochemical performance after $AlF_3$ surface modification owing to improved surface stability to fragile aqueous electrolyte. The cycle life of $LiV_3O_8$ is significantly enhanced by the presence of an $AlF_3$ coating at an optimal content of 1 wt.%. The results of powder X-ray diffraction, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma-optical emission spectrometry, and galvanostatic charge-discharge measurements confirm that the electrochemical improvement can be attributed mainly to the presence of $AlF_3$ on the surface of $LiV_3O_8$. Furthermore, the $AlF_3$ coating significantly reduces vanadium ion dissolution and surface failure by stabilizing the surface of the $LiV_3O_8$ in an aqueous electrolyte solution. The results suggest that the $AlF_3$ coating can prevent the formation of unfavorable side reaction components and facilitate lithium ion diffusion, leading to reduced surface resistance and improved surface stability compared to bare $LiV_3O_8$ and affording enhanced electrochemical performance in aqueous electrolyte solutions.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.303-303
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• 2015

In order to investigate ion release and biocompatibility of Ti-6Al-4V dental alloy by electrochemical corrosion test and MTT assay, commercial Ti-6Al-4V alloy rod (99.99% Ti, USA, Co) were used in the study. The microstructure of the alloys was examined by optical microscopy (OM), Field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), MTT assay, and corrosion test. From the polarization curves, very low current densities were obtained for Ti-6Al-4V alloys, indicating a formation of stable passive layer.

• Vacuum Magazine
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• v.3 no.4
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• pp.4-7
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• 2016

An X-ray Free Electron laser facility (PAL-XFEL) has been built in Pohang Accelerator Laboratory to provide X-ray FEL radiations for photon users. The machine consists of a 10 GeV normalconducting S-band linear accelerator and two undulator beamlines. The hard and soft X-ray beamlines will provide FEL radiations with wavelengths of 0.6 to 0.1 nm and 4.5 to 1 nm, respectively. Beam commissioning of PAL-XFEL is ongoing and user service will start in 2017. In this report, the PAL-XFEL layout and the working principle are discussed.

• Publications of The Korean Astronomical Society
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• v.8 no.1
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• pp.199-206
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• 1993

We review recent systematic investigation of the X-ray spectra of early type galaxies by using the Einstein data base and present new results by the ROSAT observations. The Einstein data suggested that the galaxies with low X-ray to optical luminosity ratio may have another very soft component. ROSAT observations confirm its presence and call for further study to understand the nature of this very soft emission. The X-ray bright galaxies have emission temperature of ${\sim}\;0.8\;keV$ and show radial gradients in the sense that X-ray emission is softer and more absorbed in the inner region.

• Journal of the Korean Society of Radiology
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• v.12 no.3
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• pp.289-295
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• 2018

Most diagnostic devices in the medical field use X-ray sources, which emit energy spectra. In radiological diagnosis, the quantitative and qualitative analyses of X-rays are essential for maintaining the image quality and minimizing the radiation dose to patients. This work aims to obtain the X-ray energy spectra used in diagnostic imaging by Monte Carlo simulation. Various X-ray spectra are simulated using a Monte Carlo simulation tool. These spectra are then compared to the reference data obtained with a tungsten anode spectral model using the interpolating polynomial (TASMIP) code. The X-ray tube voltages used are 50, 60, 80, 100, and 110 kV, respectively. CdTe and a-Se detector are used as the detectors for obtaining the X-ray spectra. Simulation results demonstrate that the various X-ray spectra are well matched with the reference data. Based on the simulation results, an appropriate X-ray spectrum, in accordance with the tube voltage, can be selected when generating an image for diagnostic imaging. The dose to be delivered to the patient can be predicted prior to examination in the diagnostic field.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.1
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• pp.60-65
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• 2007

The radiologic imaging device was implemented. It can be installed in an ambulance or used when an accident happens. After an equipment which generates X-ray generating unit with a tube in DC 12[V] had been made, a trait experiment using an oscilloscope was made. An experiment was carried out where the generated X-ray was saved as a form of a file using a digital detector. In this experiment, as a result of generating X-ray and detecting it using a digital detector, 1.67[MB]-, jpg- radical rays information could be saved. One distinct advantage of the developed radiologic imaging device is the fact that we can efficiently deal with emergency cases too far from the hospital, difficult to diagnose but treat simultaneously. By using the radiologic imaging device at the urgent scene of an accident or in a moving ambulance, we can provide the patient's X-ray information with the emergency medical specialist who is in the emergent medical center and have the patients prescribed and treated appropriately. As a result the developed emergency medical treatment can be expected.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.191-191
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• 1999

Extended X-ray Absorption Fine Structure (EXAFS)는 일반적으로 널리 사용하는 X선 회절분광기로 분석하기 힘든 chemical 또는 biological system의 structural analyses에 매우 유용한 분석방법이다. 특히 세라믹이나 유전체 비정질 재료의 미세 원자 구조에 관한 정보를 얻는데는 가장 강력한 분석방법중의 하나로 알려져 있다. 현재까지 대부분의 EXAFS 실험은 방사광 가속기를 이용하여 수행하였다. 그런데 신제품 개발의 순환주기가 급속하게 단축되는 현실적인 문제에 부응하기 위하여 실험실에서 EXAFS 실험을 수행할 수 있는 system을 개발하게 되었다. 개발한 XIEES 장비는 rotating anode 형의 18kW X-ray source, Optical system, Detection system, Stepping motor control system, vacuum system, Utility 등으로 구성하였다. Optical system에서의 6개의 Johanson type monochromator를 사용하여 분석가능한 x-ray energy range를 480eV에서 41keV까지 구현하였다. 이는 산소에서 우라늄까지 분석이 가능함을 의미하는 것으로, 산화물 연구에 많이 활용할 것으로 기대한다. XIEES는 투과 및 형광 X-ray를 검출할 수 있는 기능과 X-ray에 의해 여기 되는 모든(광전자, Aiger 전자, 이차전자)들을 검출할 수 있는 기능을 갖추고 있는데 이를 Total Electron Yield 측정이라고 한다. Total Electron Yield 측정은 박막 시료와 같이 투과가 되지 않는 시료를 분석할 뿐만 아니라, 경원소 분석, 낮은 에너지에서 흡수 edge가 나타나는 L-edge 측정을 통한 전자 구조 분석 등에 유용한다. 실험실용 XIEES 장비는 방사광가속기에 비해 x-ray flux가 크게 뒤지는 문제와 Total Electron Yield를 측정하는 데 있어서 source에서 나오는 x-ray beam이 진공용기 안에서 산란되어 이차전자를 여기하고 이 이차전자들이 전자검출기에 유입되어 측정에 영향을 미치는 background 문제 등이 있다. 이 두 가지 문제를 해결하기 위하여 Capillary tube를 사용하였다. 본 연구에서는 실험실용 XIEES 장비를 소개하고 이를 이용하여 Cu standard 시료에서 측정한 EXAFS 결과와 Capillary tube를 사용하여 얻은 x-ray flux 증진 및 background 제거 효과에 대해서 발표한다.

• Journal of Astronomy and Space Sciences
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• v.30 no.2
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• pp.83-85
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• 2013

Anomalous X-ray pulsars (AXPs) are thought to be magnetars which are young isolated neutron stars with extremely strong magnetic fields of > $10^{14}$ Gauss. Their tremendous magnetic fields inferred from the spin parameters provide a huge energy reservoir to power the observed X-ray emission. High-energy emission above 0.3 MeV has never been detected despite intensive search. Here, we present the possible Fermi Large Area Telescope (LAT) detection of ${\gamma}$-ray pulsations above 200 MeV from the AXP, 1E 2259+586, which puts the current theoretical models of ${\gamma}$-ray emission mechanisms of magnetars into challenge. We speculate that the high-energy ${\gamma}$-rays originate from the outer magnetosphere of the magnetar.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.2
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• pp.192-198
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• 2003

Recently, the Inverter type X-ray generator is rapidly replacing the conventional single-phase or three-phase X-ray generator, it has several merits of space-saving: high accuracy and reproducibility. This paper presents a 40kw(12kV, 80mA) high tension generator system for diagnosis X-ray. The control circuit and design consideration of the proposed high tension power supply are given. Issues in the design of high voltage isolating transformer are discussed. Experimental results are presented to verify the performance of the designed power supply for varying load conditions. 1'he proposed apparatus has several advantages, e. g., the fast rising time of tube voltage, accuracy and reduced component size etc.