• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.46-50
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• 2004

This paper analysed the induced current density inside human body of hot-line worker for 765kV double circuit transmission line according to locations of human body Human was modelled by several organs, which included brain, heart, lungs, liver and intestines. We applied the 3 dimensional boundary element method to calculate induced electric fields.

• 멤브레인
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• 제12권3호
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• pp.171-181
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• 2002

이온교환막의 전압-전류곡선의 plateau length를 결정하는 변수를 다양한 NaCl 농도와 유속 하에서 연구하였다. 또한, 한계전류밀도 이상의 전류에서 전기투석공정 운전의 타당성을 검토하기 위해 다양한 전류밀도의 전원을 공급하면서 0.1 M NaCl 용액의 탈염실험을 실시하여 이온의 제거효율, 전류효율, 에너지소비량, 물 분해 현상을 측정하였다. NaCl 용액의 농도와 유속이 감소하면서 확산경계층의 두께도 함께 감소하였으며, 본 확산경계층의 두께는 plateau length와도 밀접한 관련이 있는 것으로 나타났다. 탈염실험에서 측정된 이온 제거 효율 및 전류효율은 한계전류밀도 이상에서도 한계전류밀도 이하에서의 탈염실험과 크게 차이 나지 않은 것으로 보아 한계전류밀도 이상에서도 대부분의 전류는 이온교환막 표면의 물분해에 의한 것이 아니라 막을 통한 이온의 이동에 의한 것으로 사료된다. 한계전류밀도 이상에서의 탈염운전에 대한 에너지소비량은 plateau length의 영향으로 한계전류밀도 이하에서의 탈염운전 보다 다소 높지만, 한계전류밀도 이상에서는 전류밀도의 증가에도 에너지소비량이 증가하지 않았다. 이러한 결과들은 물분해 현상이 심각하게 일어나지 않는 한 한계전류밀도 이상에서도 매우 경제적으로 전기투석 공정을 운전찬 수 있다는 것을 제시해 주는 것이다.

• 한국표면공학회지
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• 제32권3호
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• pp.393-400
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• 1999

The surface characteristics of nitrogen ion implanted iron aluminides were investigated using various electrochemical methods in $H_2$$SO_4$+KSCN and HCl solutions. Nitrogen ion implantation was performed with doses of $3.0$\times$10^{17}$ /ions/$\textrm{cm}^2$ at an energy of 150keV. Nitrogen ion implanted iron aluminides increased the corrosion potential and significantly decreased grain boundary activation, the active current density, and passive current density. Nitrogen implanted iron aluminides with Mo increased the corrosion, pitting potential, repassivation potential and │$E_{pit}$-$E_{corr}$│ value. Whereas, implanted iron aluminides containing boron reduced the pitting and repassivation potential in comparison with nitrogen implanted iron aluminides with Cr and Mo.o.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권2호
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• pp.76-81
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• 2006

This paper analysed the characteristics of current density induced inside human body by 60 Hz extremely low frequency magnetic fields according to varying conductivities of human model. Human model was composed of several organs and other parts, whose shapes were expressed by spheroids or cylinders. Organs such as the brain, heart, lungs, liver and intestines were taken into account. Applying the boundary element method to the human model, we estimated effects on the induced current distribution due to differences of the organ conductivity and shape. We find organ conductivity influences most and a cross section area and a position of organ also gives effects.

• Fisheries and Aquatic Sciences
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• 제5권1호
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• pp.5-20
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• 2002

To investigate the effect of mechanical parameters on the circulation and its fluctuation in Sagami Bay, baroclinic model experiments were carried out by use of a two-layer source-sink flow in a rotating tank. In the experiment, a simple coastal topography with flat bottom was reproduced. The results show that the path of the Through Flow, which corresponds to the branch current of the Kuroshio, depends on external Rossby number (Ro) and internal Rossby number $(Ro^*)$, and divided into two regimes. For $Ro^*\leq1.0$ in which Rossby internal radius of deformation of the Through Flow is smaller than the width of the approaching channel, the current flows along the Oshima Island as a coastal boundary density current separated from the western boundary of the channel. For $Ro^*>1.0$ it changes to a jet flow along the western boundary of the channel, separated from the coast of Oshima Island. The current is independent on both Ro and Ro* in the regime of $Ro^*>1.0,\;Ro\geq0.06$ and $Ro^*\leq1.0,\;Ro\geq0.06$. The pattern of the cyclonic circulation in the inner part of the bay is also determined by Ro and Ro*. In case of $Ro^*\leq1.0$, frontal eddies are formed in the northern boundary of the Through Flow. These frontal eddies intrude into the inner part along the eastern boundary of the bay providing vorticity to form and maintain the inner cyclonic circulation. For $Ro^*>1.0$, the wakes from the Izu peninsula are superposed intensifying the cyclonic circulation. The pattern of the cyclonic circulation is divided into three types; 1) weak cyclonic circulation and the inner anticyclonic circulation $(Ro<0.12)$. 2) cyclonic circulation in the bay $(0.12\leq Ro<0.25)$. 3) cyclonic circulation with strong boundary current $(RO\geq0.25)$.

• 한국표면공학회지
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• 제37권2호
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• pp.128-136
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• 2004

Effects of alloying elements on the surface characteristics of Fe-38Al intermetallic compounds were investigated using potentiostat. The specimens were casted by the vacuum arc melting. The subsequent homogenization and the stabilization led to the homogeneous DO$_3$ structure of the specimen. After the corrosion tests, the surface of the tested specimen was observed by the optical microscopy and scanning electron microscopy(SEM). For Fe-38 at.% Al intermetallic compound, the addition of Cr and Mo proved to be beneficial in decreasing the grain boundary attack by decreasing the active current density. Addition of Band Nb resulted in a higher active current density and also a higher passive current density. These results indicated the role of Cr and Mo in improving the pitting corrosion resistance of Fe-38 at.%Al intermetallic compound. Band Nb addition to Fe-38 at.%Al accelerated the granular corrosion. Fe-38 at.%Al containing Cr and Mo showed remarkably improved pitting corrosion resistance in comparison with Band Nb addition to Fe-38 at. %Al.

• 대한수학회논문집
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• 제16권3호
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• pp.519-541
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• 2001

Magnetic Resonance Electrical Impedance Tomography(MREIT) is a new medical imaging technique for the cross-sectional conductivity distribution of a human body using both EIT(Electrical Impedance Tomography) and MRI(Magnetic Resonance Imaging) system. MREIT system was designed to enhance EIT imaging system which has inherent low sensitivity of boundary measurements to any changes of internal tissue conductivity values. MREIT utilizes a recent CDI (Current Density Imaging) technique of measuring the internal current density by means of MRI technique. In this paper, a mathematical modeling for MREIT and image reconstruction method called the alternating J-substitution algorithm are presented. Computer simulations show that the alternating J-substitution algorithm provides accurate high-resolution conductivity images.

• 전기학회논문지
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• 제57권3호
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• pp.433-438
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• 2008

This paper analyses current densities induced inside a worker using AC arc welder. Applying the boundary element method, we calculate current densities induced in organs inside a worker in case he was located at 1cm, 3cm, 5cm, 10cm, 15cm, 20cm far from a power cable of AC arc welder. As results of study, we find a maximum current density induces at a heart surface and may be higher than $10mA/m^2$ of ICNIRP guideline if he works within 15cm from a power cable.

• Computers and Concrete
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• 제21권2호
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• pp.181-187
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• 2018

In order to solve the life prediction problem of damaged coating steel bar in magnesium cement concrete, this study tries to establish the marginal distribution function by using the corrosion current density as a single degradation factor. Representing the degree of steel corrosion, the corrosion current density were tested in electrochemical workstation. Then based on the Copula function, the joint distribution function of the damaged coating was established. Therefore, it is indicated that the corrosion current density of the bare steel and coated steel bar can be used as the boundary element to establish the marginal distribution function. By using the Frank-Copula function of Copula Archimedean function family, the joint distribution function of the damaged coating steel bar was successfully established. Finally, the life of the damaged coating steel bar has been lost in 7320d. As a new method for the corrosion of steel bar under the multi-dimensional factors, the two-dimensional Copula function has certain practical significance by putting forward some new ideas.

• Journal of Magnetics
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• 제16권1호
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• pp.15-18
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• 2011

We have studied the $TiO_2$ doping effects on the flux pinning behavior of an $MgB_2$ superconductor synthesized by the in-situ solid-state reaction. From the field-cooled and zero-field-cooled temperature dependences of magnetization, the reversible-irreversible transition of $TiO_2$-doped $MgB_2$ was determined in the H-T diagram (the temperature dependence of upper critical magnetic field and irreversibility line). For comparison, the similar measurements are also obtained from SiC-doped $MgB_2$. The critical current density was estimated from the width of hysteresis loops in the framework of Bean's model at different temperatures. The obtained results manifest that nano-scale $TiO_2$ inclusions served as effective pinning centers and lead to the enhanced upper critical field and critical current density. It was concluded that the grain boundary pinning mechanism was realized in a $TiO_2$-doped $MgB_2$ superconductor.