• Title, Summary, Keyword: susceptibility

Search Result 3,538, Processing Time 0.05 seconds

Efficient Experimental Design for Measuring Magnetic Susceptibility of Arbitrarily Shaped Materials by MRI

  • Hwang, Seon-ha;Lee, Seung-Kyun
    • Investigative Magnetic Resonance Imaging
    • /
    • v.22 no.3
    • /
    • pp.141-149
    • /
    • 2018
  • Purpose: The purpose of this study is to develop a simple method to measure magnetic susceptibility of arbitrarily shaped materials through MR imaging and numerical modeling. Materials and Methods: Our 3D printed phantom consists of a lower compartment filled with a gel (gel part) and an upper compartment for placing a susceptibility object (object part). The $B_0$ maps of the gel with and without the object were reconstructed from phase images obtained in a 3T MRI scanner. Then, their difference was compared with a numerically modeled $B_0$ map based on the geometry of the object, obtained by a separate MRI scan of the object possibly immersed in an MR-visible liquid. The susceptibility of the object was determined by a least-squares fit. Results: A total of 18 solid and liquid samples were tested, with measured susceptibility values in the range of -12.6 to 28.28 ppm. To confirm accuracy of the method, independently obtained reference values were compared with measured susceptibility when possible. The comparison revealed that our method can determine susceptibility within approximately 5%, likely limited by the object shape modeling error. Conclusion: The proposed gel-phantom-based susceptibility measurement may be used to effectively measure magnetic susceptibility of MR-compatible samples with an arbitrary shape, and can enable development of various MR engineering parts as well as test biological tissue specimens.

A Study of Susceptibility Decomposition in MRI (자기 공명 영상 시스템에서 자화율 분해 영상법에 관한 연구)

  • 노용만;홍인기
    • Journal of Biomedical Engineering Research
    • /
    • v.16 no.4
    • /
    • pp.395-402
    • /
    • 1995
  • The intravoxel spin phases in magnetic resonance imaging (MRI) usually vary due to susceptibility differences of materials to be imaged. The phase variation in the voxel results in a reduction of the signal intensity. This signal intensity reduction is known as the susceptibility effect in MRI and has been studied extensively. In this paper, a new spectral decomposition technique Is proposed and the signal change due to the susceptibility effect can be analyzed. A pulse sequence for the spectral decomposition of the susceptibility was developed and applied to susceptibility imaging of venous blood possessing paramagnetic properties. The computer simulations and their corresponding experimental results obtained using both a phantom and human volunteers are reported. Key words : susceptibility effect in MRI : spectral decomposition of susceptibility effect.

  • PDF

Landslide Susceptibility Analysis and its Verification using Likelihood Ratio, Logistic Regression and Artificial Neural Network Methods: Case study of Yongin, Korea

  • Lee, S.;Ryu, J. H.
    • Proceedings of the KSRS Conference
    • /
    • /
    • pp.132-134
    • /
    • 2003
  • The likelihood ratio, logistic regression and artificial neural networks methods are applied and verified for analysis of landslide susceptibility in Yongin, Korea using GIS. From a spatial database containing such data as landslide location, topography, soil, forest, geology and land use, the 14 landsliderelated factors were calculated or extracted. Using these factors, landslide susceptibility indexes were calculated by likelihood ratio, logistic regression and artificial neural network methods. Before the calculation, the study area was divided into two sides (west and east) of equal area, for verification of the methods. Thus, the west side was used to assess the landslide susceptibility, and the east side was used to verify the derived susceptibility. The results of the landslide susceptibility analysis were verified using success and prediction rates. The v erification results showed satisfactory agreement between the susceptibility map and the exis ting data on landslide locations.

  • PDF

The Rapid Drug Susceptibility Testing of Mycobacterium tuberculosis by GenoType$^{(R)}$ MTBDRplus in Contaminated Specimen

  • Heo, Reun;Kim, Yoon-Sik
    • Biomedical Science Letters
    • /
    • v.19 no.4
    • /
    • pp.330-337
    • /
    • 2013
  • There are several methods currently being used to diagnose tuberculosis in patients, such as smear, PCR, tuberculosis culture and X-ray. For a proper medical treatment, antimicrobial susceptibility test and rapid drug susceptibility testing have been operated. Tuberculosis bacilli usually need 3~8 weeks of culture period because of delay in RNA synthesis and require 15~22 hours for generation. After a germ raises in culture, we initiated antimicrobial susceptibility test for a proper treatment. It has some difficulties to give a proper prescription for a tuberculosis patient because antimicrobial susceptibility test requires 4 weeks. To supplement this, we are practicing drug susceptibility testing which allow us to know the sensibility of RMP and INH after 2 or 3 days. But this is only possible when more than 2 positive germ. Therefore, we should practice rapid drug susceptibility testing with culture test. But if media is contaminated by other germs except Mycobacterium tuberculosis, it's hard to interpret result about culture test and to practice antimicrobial susceptibility test and rapid drug susceptibility testing. Because we have to practice again smear, culture test after extracting specimen from the patient, time is consumed and proper patient treatment is postponed. To address these problems and quick patient treatment, rapid drug susceptibility testing is practiced by using GenoType$^{(R)}$ MTDRplus method. As a result of this method we detected sensibility 10 and 7 cases and resistance 0 and 3 cases using RIM and INH respectively with other 1 case toward medicals out of the total 11 test. In conclusion rapid drug susceptibility testing can be used from the contaminated specimen after elimination of contaminated source from culture and proved that it can be practiced for rapid examination of a tuberculosis patient.

Electromagnetic Susceptiblity Experiments for Battery Protection Circuit Module (배터리 보호회로 모듈에 대한 전자파 내성 실험)

  • Park, Kyung-Je;Yoo, Jong-Gyeong;Lee, Dae-Heon;Yeo, Junho;Cho, Young-Ki;Kim, Jong-Kyu
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
    • /
    • /
    • pp.57-58
    • /
    • 2017
  • In this paper, we have studied electromagnetic susceptibility tests of the battery protection circuit module of a lithium ion battery. Electromagnetic susceptibility tests can be divided into conducted susceptibility for electromagnetic waves flowing through power lines, input / output lines, antenna ports, and radiated susceptibility for spatially radiated electromagnetic waves. A lithium ion battery of S company was used as an experimental sample, and conducted susceptibility tests were conducted on Surge (IEC 61000-4-5), Ring wave (IEC 61000-4-12), and Damped oscillatory wave(IEC 61000-4-18). Radiated susceptibility tests were performed according to IEC 61000-4-3.

  • PDF

Landslide Susceptibility Analysis in Baekdu Mountain Area Using ANN and AHP Method

  • Quan, Hechun;Moon, Hongduk;Jin, Guangri;Park, Sungsik
    • Journal of the Korean Geoenvironmental Society
    • /
    • v.15 no.12
    • /
    • pp.79-85
    • /
    • 2014
  • To analyze the landslide susceptibility in Baekdu mountain area in china, we get two susceptibility maps using AcrView software through weighted overlay GIS (Geographic Information System) method in this paper. To assess the landslide susceptibility, five factors which affect the landslide occurrence were selected as: slope, aspect, soil type, geological type, and land use. The weight value and rating value of each factor were calculated by the two different methods of AHP (Analytic Hierarchy Process) and ANN (Artificial Neural Network). Then, the weight and rating value was used to obtain the susceptibility maps. Finally, the susceptibility map shows that the very dangerous areas (0.9 or higher) were mainly distributed in the mountainous areas around JiAnShi, LinJiangShi, and HeLongShi near the china-north Korea border and in the mountainous area between the WangQingXian and AnTuXian. From the contrast two susceptibility map, we also Knew that The accuracy of landslide susceptibility map drew by ANN method was better than AHP method.

Evaluation of the Usefulness of PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) Technique to Reduce the Magnetic susceptibility artifact (Magnetic susceptibility artifact를 줄이기 위한 PROPELLER 확산강조영상기법의 유용성에 대한 평가)

  • Cho, Jae-Hwan
    • Journal of Digital Contents Society
    • /
    • v.11 no.1
    • /
    • pp.73-78
    • /
    • 2010
  • This study attempted to examine whether the propeller diffusion weighted image method may remove magnetic susceptibility artifacts caused by metallic materials. A comparison of occurrence rates of magnetic susceptibility artifacts in the four regions, both temporal lobes, pons, and orbit, between b = 0 and b = 1,000 s/mm2 images was made after obtaining echo-planar diffusion weighted image, propeller diffusion weighted image, and ADC map images, respectively, from a total of 20 patients who had MRI shots taken of their brain and were found to be with retained metallic foreign bodies within their teeth using a 3.0T MR scanner. In the case of echo-planar diffusion weighted image technique, the presence of metallic materials may bring in some limits on accurate diagnosis due to magnetic susceptibility artifacts, while the propeller diffusion weighted image technique where magnetic susceptibility artifacts decrease is expected to be more useful in ensuring accurate diagnosis in the clinical context.

Development and application of artificial neural network for landslide susceptibility mapping and its verfication at Janghung, Korea

  • Yu, Young-Tae;Lee, Moung-Jin;Won, Joong-Sun
    • Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
    • /
    • /
    • pp.77-82
    • /
    • 2003
  • The purpose of this study is to develop landslide susceptibility analysis techniques using artificial neural network and to apply the developed techniques to the study area of janghung in Korea. Landslide locations were identified in the study area from interpretation of satellite image and field survey data, and a spatial database of the topography, soil, forest and land use were consturced. The 13 landslide-related factors were extracted from the spatial database. Using those factors, landslide susceptibility was analyzed by artificial neural network methods, and the susceptibility map was made with a e15 program. For this, the weights of each factor were determinated in 5 cases by the backpropagation method, which is a type of artificial neural network method. Then the landslide susceptibility indexes were calculated using the weights and the susceptibility maps were made with a GIS to the 5 cases. A GIS was used to efficiently analyze the vast amount of data, and an artificial neural network was turned out be an effective tool to analyze the landslide susceptibility.

  • PDF

Naval ship's susceptibility assessment by the probabilistic density function

  • Kim, Kwang Sik;Hwang, Se Yun;Lee, Jang Hyun
    • Journal of Computational Design and Engineering
    • /
    • v.1 no.4
    • /
    • pp.266-271
    • /
    • 2014
  • The survivability of the naval ship is the capability of a warship to avoid or withstand a hostile environment. The survivability of the naval ship assessed by three categories (susceptibility, vulnerability and recoverability). The magnitude of susceptibility of a warship encountering with threat is dependent upon the attributes of detection equipment and weapon system. In this paper, as a part of a naval ship's survivability analysis, an assessment process model for the ship's susceptibility analysis technique is developed. Naval ship's survivability emphasizing the susceptibility is assessed by the probability of detection, and the probability of hit. Considering the radar cross section (RCS), the assessment procedure for the susceptibility is described. It's emphasizing the simplified calculation model based on the probability density function for probability of hit. Assuming the probability of hit given a both single-hit and multiple-hit, the susceptibility is accessed for a RCS and the hit probability for a rectangular target is applied for a given threat.

A Comparative Analysis of Landslide Susceptibility Assessment by Using Global and Spatial Regression Methods in Inje Area, Korea

  • Park, Soyoung;Kim, Jinsoo
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
    • /
    • v.33 no.6
    • /
    • pp.579-587
    • /
    • 2015
  • Landslides are major natural geological hazards that result in a large amount of property damage each year, with both direct and indirect costs. Many researchers have produced landslide susceptibility maps using various techniques over the last few decades. This paper presents the landslide susceptibility results from the geographically weighted regression model using remote sensing and geographic information system data for landslide susceptibility in the Inje area of South Korea. Landslide locations were identified from aerial photographs. The eleven landslide-related factors were calculated and extracted from the spatial database and used to analyze landslide susceptibility. Compared with the global logistic regression model, the Akaike Information Criteria was improved by 109.12, the adjusted R-squared was improved from 0.165 to 0.304, and the Moran’s I index of this analysis was improved from 0.4258 to 0.0553. The comparisons of susceptibility obtained from the models show that geographically weighted regression has higher predictive performance.