• 한국지구물리탐사학회:학술대회논문집
• /
• 2003.11a
• /
• pp.441-448
• /
• 2003

Refraction tomography requires an algorithm for efficiently computing the traveltimes and their $Fr\'{e}chet$ derivatives. We have attempted to solve the damped wave field using the frequency domain finite element model ing and then invoked the reciprocity theorem to calculate the $Fr\'{e}chet$ derivative of the traveltime with respect to the subsurface parameter. Then, we used a damped least square method to invert the traveltimes of the Marmousi 2 model. Numerical tests demonstrate that the refraction tomography with large aperture data can be used to estimate the smooth velocity model for the prestack depth migration.

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.14
• /
• pp.5595-5597
• /
• 2015

Electrical impedance tomography (EIT) is a new non-invasive, mobile screening method which does not use ionizing radiation to the human breast. It is based on the theory that cancer cells display altered local dielectric properties, thus demonstrating measurably higher conductivity values. This article reviews the utilisation of EIT in breast cancer detection. It could be used as an adjunct to mammography and ultrasonography for breast cancer screening.

• Journal of the Korean Mathematical Society
• /
• v.45 no.1
• /
• pp.97-119
• /
• 2008

Electrical impedance tomography (EIT) problem with anisotropic anomalous region is formulated in a few different ways using boundary integral operators. The Frechet derivative of Neumann-to-Dirichlet map is computed also by using boundary integral operators and the boundary of the anomalous region is approximated by trigonometric expansion with Lagrangian basis. The numerical reconstruction is done in case that the conductivity of the anomalous region is isotropic.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.23 no.2
• /
• pp.278-284
• /
• 1986

There are considerabel interests in the use of acoustical lengths for characterization of scattered data required in diffraction tomography. In this paper, we present two new methods, calculation of acoustical lengths by Hibert transform and estimate on of integrated values on the scan lines from calcualted vales. These techniques offer insight into the acquisition of projection data in diffraction tomography. The validity of the proposed methods has bee confirmed by computer simulation.

• Imaging Science in Dentistry
• /
• v.41 no.3
• /
• pp.135-137
• /
• 2011

Impaction of third molar is a common developmental abnormality. However, ectopic impaction of the mandibular third molar in condylar region is an extremely rare condition. This report describes a case of impacted tooth in the mandibular condyle without any associated pathologic condition. Also, this report presents the spatial relationship of the impacted mandibular third molar to the surrounding anatomic structures using cone beam computed tomography.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05a
• /
• pp.87-91
• /
• 2002

본 연구는 탐지 대상물체의 형상인식 이 가능한 비접촉, 원격 탐지장치의 개발에 관한 것이다. 형체인식용 비접촉 시스템은 주로 Magneto-Impedance법과 Magneto-Inductance법이 있 으며, Magneto- Inductance법은 왜곡이 적고, 인체나 탐지대상물체에 손상을 가져오지 않는다. 본 연구에서는 2극으로 디자인 된 Magnetic Tomography System을 이용하여 물체의 위치에 따른 투자율 변화량을 계산 및 실측하였다.

• Applied Microscopy
• /
• v.46 no.4
• /
• pp.176-178
• /
• 2016

Efficient neural circuit reconstruction requires sufficient lateral and axial resolution to resolve individual synapses and map a large enough volume of brain tissue to reveal the molecular identity and origin of these synapses. Sparse circuit reconstruction using array tomography meets many of these requirements but also has some limitations. In this minireview, the advantages and disadvantages of applicable imaging techniques will be discussed.

• Journal of Powder Materials
• /
• v.19 no.1
• /
• pp.67-71
• /
• 2012

The present paper gives an overview about the Atom Probe Tomography technique and its application to powder materials. The preparation of needle-shaped Atom Probe specimens from a single powder particle using focused-ion-beam milling is described. Selected experimental data on mechanically alloyed (and sintered) powder materials are presented, giving insight into the atomic-scale elemental redistribution occurring under powder metallurgical processing.

• Proceedings of the KSEEG Conference
• /
• 2003.04a
• /
• pp.150-153
• /
• 2003

High-resolution imaging of electrical conductivity has been the subject of many studies in crosshole tomography using electromagnetic (EM) fields (Zhou et al., 1993; Wilt et al., 1995; Alumbaugh and Morrison, 1995; Newman, 1995; Alumbaugh and Newman, 1997). Although the theoretical understanding and associated field practices for crosshole EM methods are relatively mature, fast and stable imaging of crosshole EM data is still a challenging problem. (omitted)

• Journal of Korea Multimedia Society
• /
• v.19 no.8
• /
• pp.1371-1376
• /
• 2016

In this paper, an iterative method is proposed to perform attenuation correction and image reconstruction simultaneously for positron emission tomography, by using the time-of-flight information. Numerical simulation results are presented to demonstrate an improved performance of the proposed method in attenuation correction and image reconstruction.