• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1304-1310
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• 2021

Two-phase flow, especially gas-liquid two-phase flow, has a wide application in industrial field. The diagnosis of two-phase flow parameters, which directly determine the flow and heat transfer characteristics, plays an important role in providing the design reference and ensuring the security of online operation of two-phase flow system. Computer tomography (CT) is a good way to diagnose such parameters with imaging method. This paper has proposed a novel image reconstruction method for thermal neutron CT of two-phase flow with improved simulated annealing (ISA) algorithm, which makes full use of the prior information of two-phase flow and the advantage of stochastic searching algorithm. The reconstruction results demonstrate that its reconstruction accuracy is much higher than that of the reconstruction algorithm based on weighted total difference minimization with soft-threshold filtering (WTDM-STF). The proposed method can also be applied to other types of two-phase flow CT modalities (such as X(𝛄)-ray, capacitance, resistance and ultrasound).

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.3
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• pp.189-203
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• 2008

The physical and chemical properties of radioactive waste drums, which have been temporarily stored on site, should be characterized before their shipment to a disposal facility in order to prove that the properties meet the acceptance guideline. The investigation of NDT(Nondestructive Test) method was figured out that the contents in drum, the quantitative analysis of free standing water and void fraction can be examined with X-ray NDT techniques. This paper describes the characteristics of X-ray NDT such as its principles, the considerations for selection of X-ray system, etc. And then, the waste drum characteristics such as drum type and dimension, contents in drum, etc. were examined, which are necessary to estimate the optimal X-ray energy for NDT of a drum. The estimation results were that: $(R)\acute{A}$ the proper X-ray energy is under 3 MeV to test the drums of 320 ${\beta}\S$ and less; $(R)\ddot{E}$ both X-ray systems of 450 keV and/or 3 MeV might be needed considering the economical efficiency and the realization. The number of drums that can be tested with 450 keV and 3 MeV X-ray system was figured out as 42,327 and 18,105 drums (based on storage of 2006. 12), respectively. Four testing scenarios were derived considering equipment procurement method, outsourcing or not, etc. The economical and feasibility assessment for the scenarios was resulted in that an optimal scenario is dependent on the acceptance guide line, the waste generator's policy on the waste treatment and the delivery to a disposal facility, etc. For example, it might be desirable that a waste generator purchases two 450 keV mobile system to examine the drums containing low density waste, and that outsourcing examination for the high density drums, if all NDT items such as quantitative analysis for 'free standing water' and 'void fraction', and confirmation of contents in drum have to be characterized. However, one 450 keV mobile system seems to be required to test only the contents in 13,000 drums per year.

• Economic and Environmental Geology
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• v.56 no.3
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• pp.293-300
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• 2023

The Shape Preferred Orientation (SPO) method has been used to analyze the orientation of fault motion, which is utilized as basic data for fault kinematics studies. The rigid grains, which as quartz, feldspar, and rock fragments, in the fault gouge are arranged in the P-shear direction through rigid body rotation by a given shear stress. Using this characteristic, the fault motion can be estimated from the SPO inversely. Recently, a method for securing precision and reliability by measuring 3D-SPO using X-ray CT images and examining the shape of a large number of particles in a short time has been developed. As a result, the SPO method analyzes the orientation of thousands to tens of thousands of particles at high speed, suggests the direction of fault motion, and provides easy accessibility and reliable data. In addition, the shape information and orientation distribution data of particles, which are by-products obtained in the SPO analysis process, are expected to be used as basic data for conducting various studies such as the local deformation of fault rocks and the fault generation mechanism.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.465-468
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• 1997

A Study on Computer Assisted Diagnosis (CAD) system extract ing lung cancer part from Digital X-ray Computerized Tomography(CT) image is discussed in this paper. It is very crucial to segment the image of lung into the three organ area such as inside, outside and the hilum so that the variant image processing algorithm can be applied an each area respectively. In this paper, the efficient algorithm extracting lung cancer part is proposed with characterizing lung hilum part and its associated vessel patterns.

• Journal of Biomedical Engineering Research
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• v.30 no.6
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• pp.476-481
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• 2009

The most troublesome artifacts in micro computed tomography (micro-CT) are ring artifacts. The ring artifacts are caused by non-uniform sensitivity and defective pixels of the x-ray detector. These ring artifacts seriously degrade the quality of CT images. In flat-panel detector based micro-CT systems, the ring artifacts are hardly removed by conventional correction methods of digital radiography, because very small difference of detector pixel signals may make severe ring artifacts. This paper presents a novel method to remove ring artifacts in flat-panel detector based micro-CT systems. First, the bad lines of a sinogram which are caused by defective pixels of the detector are identified, and then, they are corrected using a cubic spline interpolation technique. Finally, a ring artifacts free image is reconstructed from the corrected projections. We applied the method to various kinds of objects and found that the image qualities were much improved.

• Journal of Korea Multimedia Society
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• v.1 no.1
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• pp.45-55
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• 1998

In the tele-medical system, the broadband network for multimedia telecommunication and the multimedia terminal equipment for the remote access of the tele-medical information are essential. Especially, the tele-medical terminal equipment should provide the multimedia GUI environment in order to support the similar medical process by the tele-medical system. In this paper, we present a multimedia GUI (Graphic User Interface) for a Multimedia Tele-Medical System (TeleMedi_GUI) based on ATM/B-ISDN. In the tele-medical system, one workstation is used for the multimedia data server that is supporting multiple client terminals that are connected by the ATM network. The client terminals are based on Multimedia Personal Computers, and provide the remote access environment of the tele-medical database. We also developed the remote access protocols among the clients and the server to access multimedia medical information of the multimedia server. With using the TeleMedi_GUI, the doctors can examine and treat patients efficiently, using image data like X-ray/CT and voice data such as the S-ray diagnosis. The result of this paper can be applied to the following areas: 1) the implementation of the advanced medical service system interconnecting the small-scale health center and general hospitals, 2) the development of a fully computerized medical information system within the hospital.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.4
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• pp.301-307
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• 2010

Purpose: The objectives of the current study are to assess the accuracy of X-Ray Micro Computed Tomography (microCT) in measuring enamel thickness and to evaluate enamel thickness in maxillary incisors of Koreans. Materials and methods: Five maxillary incisors were embedded in resin block. These teeth were longitudinally sectioned labiolingually through the medial axis. After polishing, the teeth were scanned using a microCT (X-EYE SYSTEM; DRGEM, Seoul, Korea). On a scanning electron microscope (S-4300; Hitachi, Tokyo, Japan) (${\times}20$) and a microCT, nearly identical planes were reconstructed. In each tooth, the thickness of labial enamel was measured 1, 3 and 5 mm above the cementoenamel junction (CEJ). Thus, the accuracy of the microCT was evaluated. In addition, using 26 maxillary central incisors and 11 maxillary lateral incisors, in the medial axis and 2 mm remote areas mesially and distally from the medial axis, the thickness of labial enamel was measured 1, 3 and 5 mm above the CEJ along the long axis of the teeth. Results: Measurements from nearly identical planes in physical and microCT sections differed by 3.81%. An independent t-test was performed and this showed that there were no significant differences in the measurements between the two methods. Mean values of labial enamel thickness in maxillary central incisors 1, 3 and 5 mm above the CEJ were $0.32{\pm}0.01$, $0.50{\pm}0.0.2$ and $0.70{\pm}0.02\;mm$, respectively. Mean values of labial enamel thickness in maxillary lateral incisors 1, 3 and 5 mm above the CEJ were $0.30{\pm}0.01$, $0.55{\pm}0.03$ and $0.80{\pm}0.02\;mm$, respectively. Conclusion: In measuring enamel thickness, microCT is one of useful way of measurement. So according to the results of this research, when restoring a porcelain laminate veneer on maxillary incisors in Koreans, careful consideration is needed in the amount of enamel reduction.

• Korean Journal of Digital Imaging in Medicine
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• v.9 no.2
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• pp.5-9
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• 2007

As developing the medical treatment image portion with the change of these times, PACS, which is able to digitalize image portion data, has a lot of data-based image data. Applying this PACS, we would like to settle down RNSXI(real-name shooting X -ray of inspector) system. We interviewed with P ACS's operators of university hospitals which is using PACS in Seoul about the present conditions whether using of RNSXI or not. And we inquired the RNSXI equipments, applying PACS database, and Interface conditions undertook to do in our hospital. All university hospitals in Seoul are set up the P ACS system. But no hospital use the RNSXI. In our hospital, we can check inspector' name or initials who exposure x-ray with the PACS Viewer by looking over equipments(CR, DR, US, MG, MR, CT) and Interface of the DICOM Header data. However, some equipments like RF and Angio can not check inspector' name or initials. Under the Film/System environment, RNSXI system has been used frequently like that inspector's signature or initial added to a patient data. Though the digital medical treatment was developed, RNSXI system was declined. It is necessary to using RNSXI system in order to improving radiologists' rights, even if it is not under the application of the medical treatment image laws. If RNSXI system use, radiologists should specialize in their major and the Repeat rate should be reduced. In environment of PACS, RNSXI system can be used by linking both the equipments and the Interface with a production enterprise of P ACS. Therefore RNSXI system applying the P ACS datebase should settle down in our medical system for being provided lots of data.

• Imaging Science in Dentistry
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• v.48 no.3
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• pp.167-176
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• 2018

Purpose: In the age of X-ray computed tomography (CT) and digital volume tomography (DVT), with their outstanding post-processing capabilities, indications for planar radiography for the study of the dentition of ancient Egyptian mummies may easily be overlooked. In this article, the advantages and limitations of different approaches and projections are discussed for planar oral and maxillofacial radiography using portable digital X-ray equipment during archaeological excavations. Furthermore, recommendations are provided regarding projections and sample positioning in this context. Materials and Methods: A total of 55 specimens, including 19 skeletonized mandibles, 14 skeletonized skulls, 18 separate mummified heads, and 4 partially preserved mummies were imaged using portable digital X-ray equipment in the course of archaeological excavations led by the University of Basel in the Valley of the Kings between 2009 and 2012. Images were evaluated by 2 authors with regard to the visibility of diagnostically relevant dental structures using a 4-point grading system(Likert scale). Results: Overall, the visibility of diagnostically relevant dental structures was rated highest by both authors on X-ray images acquired using a dental detector. The tube-shift technique in the lateral projections of mandibular dentition achieved the second-best rating, and lateral projections achieved the third-best rating. Conclusion: Conventional planar digital X-ray imaging, due to its ubiquity, remains an excellent method-and often the only practicable one-for examining the skulls and teeth of ancient Egyptian mummies under field conditions. Radiographic images of excellent diagnostic quality can be obtained, if an appropriate methodology regarding the selected projections and sample placement is followed.

• Electronics and Telecommunications Trends
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• v.29 no.5
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• pp.96-104
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• 2014

1895년 독일 과학자 Wilhelm Roentgen 박사가 X-ray를 발견하고 미국의 Herman Carr가 MRI(Magnetic Resonance Imaging)의 기본 원리를 개발하여 발표한 이후 전자기장을 이용한 비침습적 의료영상 이미지 시스템은 놀라운 발전을 계속하여 왔다. 하지만, X-ray, CT(Computed Tomography), PET(Positron Emission Tomography)의 경우는 방사능의 사용과 조영제의 독성이라는 문제로 인하여 안전성에 대한 계속적인 문제를 야기해왔고 상대적으로 안전성이 입증된 MRI의 경우는 장비 자체 및 운용비가 일반화되기에는 고가여서 우리나라를 포함한 선진국에서도 아주 제한적으로 운영되고 있는 실정이다. 따라서, 세계적으로도 이러한 문제를 해결하기 위하여 안전하면서도 상대적으로 저렴한 비용으로 운용이 가능한 의료영상장비를 개발하기 위하여 많은 노력들이 경주되고 있어 관련 연구동향 및 산업화 동향을 소개하고자 한다.