• International Journal of Fuzzy Logic and Intelligent Systems
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• 제6권1호
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• pp.47-51
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• 2006

Electrical resistance tomograpy (ERT) maps resistivity values of the soil subsurface and characterizes buried objects. The characterization includes location, size, and resistivity of buried objects. In this paper, truncated least squares (TLS) is presented for the solution of the ERT image reconstruction. Results of numerical experiments in ERT solved by the TLS approach is presented and compared to that obtained by the Gauss-Newton method.

• 전기전자학회논문지
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• 제20권3호
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• pp.226-234
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• 2016

전기 저항 단층촬영법(ERT)은 대상체 내부 단면의 저항률 분포를 추정하고 이를 영상화하는 기술이다. ERT의 영상복원은 매우 비정치성이 강한 역문제의 일종으로 의미있는 영상을 얻기 위해서는 조정기법이 사용된다. 대표적으로 l2-norm 조정기법, l1-norm 조정기법, Total Variation 조정기법이 사용되며, 조정기법에 따라 ERT의 영상복원 성능이 달라진다. 즉, 상황에 맞는 적절한 조정기법의 사용은 ERT 영상 복원을 개선할 수 있다. 따라서, 본 논문에서는 모의실험을 통하여 상황에 따른 세 가지 조정기법의 영상복원 성능을 비교하였다.

• 전기전자학회논문지
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• 제18권1호
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• pp.8-18
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• 2014

Electrical resistance tomography (ERT) has high temporal resolution characteristics therefore it is used as an alternative technique to visualize two-phase flows. The image reconstruction in ERT is highly non-linear and ill-posed hence it suffers from poor spatial resolution. In this paper, the inverse problem is solved with homogeneous data used as a prior information to reduce the condition number of the inverse algorithm and improve the spatial resolution. Numerical experiments have been carried out to illustrate the performance of the proposed method.

• 전기전자학회논문지
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• 제26권3호
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• pp.475-482
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• 2022

Signal pre-processing and post-processing are some areas of study around electrical resistance tomography due to the low spatial resolution of pixel-based reconstructed images. In addition, methods that improve integrity and noise reduction are candidates for application in ERT. Lately, formulations of image processing methods provide new implementations and studies to improve the response against noise. For example, compact variational mode decomposition has recently shown good performance in image decomposition and segmentation. The results from this first approach of C-VMD to ERT show an improvement due to image segmentation, providing filtering of noise in the background and location of the target.

• 한국산학기술학회논문지
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• 제14권7호
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• pp.3460-3467
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• 2013

본 논문에서는 2차원 대지구조를 분석하기 위해 ERT(electrical resistance tomography) 방법을 사용하여 대지모델을 영상복원하는 방법들을 수치적인 실험방법들을 통해 비교분석한다. 영상복원을 위한 역산방법으로는 Gauss-Newton, TLS(truncated least squares), 그리고 SIRT(simultaneous iterative reconstruction technieque) 알고리즘들이 제시되고 대지저항을 측정하기 위한 전극법은 대표적인 웨너와 슐럼버거 측정방법을 사용한다. 컴퓨터 시뮬레이션을 통해 Gauss-Newton과 TLS 알고리즘이 대지모델의 2차원 영상복원에서 적합하다는 것을 보인다.

• 전자공학회논문지
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• 제53권4호
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• pp.117-128
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• 2016

대지의 접지 시스템 설치는 안전성과 전기 기기의 올바른 작동을 위해 필수적이며, 대지 파라미터, 특히 토양의 저항률은 대지 접지 시스템 설계에서 결정되어야 한다. 토양의 저항률을 측정하기 위한 가장 흔한 방법은 Wenner의 4전극 방법이 있으며, 이 방법은 1차원의 저항률을 얻기 위하여 가변 전극 간격을 갖는 큰 측정 세트가 요구되어 번거롭고, 시간소모가 많으며 비용이 많이 든다. 전기 저항 단층촬영법은 저비용이며 빠른 측정이 가능하다는 장점 때문에 토양의 저항률 분포를 추정하기 위해 적용될 수 있다. 전기 저항 단층은 관심지역에 놓인 전극에서 얻은 측정데이터를 사용하여 토양 저항률 분포를 특성화한다. 이때 전기 단층 촬영법의 역문제는 비선형성이 강하여 저항률 분포를 추정하기 위하여 Tikhonov 조정 방법을 갖는 반복적 Gauss-Newton 방법을 사용한다. 다양한 시뮬레이션을 수행하여 3차원 토양의 저항률 분포를 추정하는데 전기 저항 단층 촬영법은 유용한 성능을 제공하고 있음을 확인하였다.

• Nuclear Engineering and Technology
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• 제46권1호
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• pp.109-116
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• 2014

An electrical resistance tomography (ERT) technique combining the particle swarm optimization (PSO) algorithm with the Gauss-Newton method is applied to the visualization of two-phase flows. In the ERT, the electrical conductivity distribution, namely the conductivity values of pixels (numerical meshes) comprising the domain in the context of a numerical image reconstruction algorithm, is estimated with the known injected currents through the electrodes attached on the domain boundary and the measured potentials on those electrodes. In spite of many favorable characteristics of ERT such as no radiation, low cost, and high temporal resolution compared to other tomography techniques, one of the major drawbacks of ERT is low spatial resolution due to the inherent ill-posedness of conventional image reconstruction algorithms. In fact, the number of known data is much less than that of the unknowns (meshes). Recalling that binary mixtures like two-phase flows consist of only two substances with distinct electrical conductivities, this work adopts the PSO algorithm for mesh grouping to reduce the number of unknowns. In order to verify the enhanced performance of the proposed method, several numerical tests are performed. The comparison between the proposed algorithm and conventional Gauss-Newton method shows significant improvements in the quality of reconstructed images.

• 전자공학회논문지SC
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• 제49권4호
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• pp.36-44
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• 2012

전기 임피던스 단층촬영법은 대상물의 경계면에 부착된 여러 개의 전극들을 통해 전류를 주입하고 이에 유기되는 전압을 측정한 후, 이를 바탕으로 대상물 내부의 도전율(또는 저항률) 분포를 영상으로 복원하는 비교적 새로운 영상복원 기법이다. 본 논문에서는, 대상물 내부의 저항률 분포를 추정하기 위해서 전극사이의 전기저항과 저항률 분포와의 관계를 선형으로 가정하고, 이 선형 관계로부터 가중행렬을 계산한 후, 수정된 반복 Landweber 알고리즘을 적용하였다. 그리고 제안한 방법의 수렴시간을 줄이고 영상 복원의 정확도를 향상시키고자 목적 함수를 최소화하는 최적의 step length를 찾아 제안한 방법에 적용하였다. 몇 가지 시나리오를 설정하고 모의실험을 통해 제안된 방법의 영상 복원 성능을 평가한 결과, 비교적 양호한 복원 성능을 나타내었다.

• 한국잠사곤충학회지
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• 제51권2호
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• pp.123-129
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• 2013

The purpose of this study is to investigate the effects of supplementation of mulberry powder, mulberry extract and silkworm powder during the 8 weeks of resistance exercise on muscle increase of rats. Fifty males, Sprague-Dawley rat, were randomly divided into 5 groups: CON(control group, n = 10), REG(resistance exercise group, n = 10), MP REG(mulberry powder intake and resistance exercise group, n = 10), ME REG(mulberry extract intake and resistance exercise group, n = 10) and SP REG(silkworm powder intake and resistance exercise group, n = 10). After climbing the ladder without weights during the 1 week of adaptation period, the rats in the resistance exercise group were trained to climb a 0.98-m vertical(80 degree incline) ladder with weights in their tail during 7 weeks(10 times each day, 2 days per week). After exercise, the skeletal muscle was extracted from the flexor hallucis longus. The absolute weight of skeletal muscle was measured by the electronic balance and the relative weight of skeletal muscle about the weight was calculated. The strength and density of legs muscle were analyzed by the computed tomography scan. After 8 weeks of resistance exercise, the absolute weight of skeletal muscle wasn't significant, but it increased in MP REG 8%, ME REG 8% and SP REG 10% compared to REG. The relative weight of skeletal muscle increased significantly in SP REG compared to REG (p < 0.05). Additionally, there was a significant increase of density and strength of the forelegs in SP REG compared to CON (p < 0.05). However, there was no significant increase of density and strength of the hind legs. In conclusion, regular resistance exercise made rats muscle increase and there was more muscle increase effected by providing silkworm.

• 전기학회논문지
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• 제65권8호
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• pp.1430-1435
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• 2016

Electrical impedance tomography (EIT) has been applied to measure the location of external disturbance using a phantom and conductive yarns. According to the test results, the addition of carbon nanotube particles into the phantom does not show remarkable improvement in location errors. On the other hand combined fabric, conductive yarns with fabric, and non-woven fabric, were added to evaluate its performance as a fabric sensor. The combined fabric resulted in a decrease of 21.5% in the circumferential location error and a decrease of 50% in the radial location error, compared to those of the yarns. Additionally, it was revealed that the measurement error is almost linearly proportional to the conductivity of the phantom liquid and resistance of the conductive yarns. The combined fabric can be a promising material for fabric sensors in sports utilities and medical devices.