Visualization of Magnetic Domains in Electrical Steel Using High-Resolution Dark-Field Imaging

김영주,김종열,Daniel Seth Hussey,Oh Youl Kwon,이승욱 대한금속·재료학회 2019 대한금속·재료학회지 Vol.57 No.6

Electrical steel is a soft magnetic steel material used in electric devices such as transformers and motors. The performance of these electric devices is primarily related to the magnetic properties of electrical steel, and the assessment of the magnetic properties of electrical steel has been considered an important topic. We use neutron grating interferometry, which is an imaging technique for visualizing the magnetic domain of electrical steel as the evaluation of magnetic properties. The dark-field image provided by neutron grating interferometry shows a sensitive contrast with respect to the magnetic domain of electrical steel due to the small angle neutron scattering generated at the domain wall. The Talbot-Lau interferometer was installed, and the feasibility test of high-resolution dark-field imaging was conducted at cold neutron imaging beamline of the NIST Center for Neutron Research. The dark-field image of electrical steel was compared with the magnetic domain image observed by the Bitter pattern based on the magnetic powder method to prove the validity of neutron grating interferometry. The dark-field image visualizes the magnetic domains of electrical steel, more detailed domain walls regardless of laser-irradiated lines than Bitter pattern result.

Physical and electrical properties of PLA-carbon composites

Kang Z. Khor,Cheow K. Yeoh,Pei L. Teh,Thangarajan Mathanesh,Wee C. Wong Techno-Press 2024 Advances in materials research Vol.13 No.3

Polylactic acid or polylactide (PLA) is a biodegradable thermoplastic that can be produced from renewable material to create various components for industrial purposes. In 3D printing technology, PLA is used due to its good mechanical, electrical, printing properties, environmentally friendly and non-toxic properties. However, the physical properties and excellent electrical insulation properties of PLA have limited its application. In this study, with the carbon black (CB) as filler added into PLA, the lattice spacing and morphology were investigated by using X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The physical properties of PLA-carbon composite were evaluated by using tensile test, shore D hardness test and density and voids measurement. Impedance test was conducted to investigate the electrical properties of PLA-Carbon composites. The results demonstrate that the inclusion of carbon black as filler enhances the physical properties of the PLA-carbon composites, including tensile properties, hardness, and density. The addition of carbon black also leads to improved electrical conductivity of the composites. Better enhancement toward the electrical properties of PLA-carbon composites is observed with 1wt% of carbon black in N774 grade. The N550 grade with 2wt% of carbon black shows better improvement in the physical properties of PLA-carbon composites, achieving 10.686 MPa in tensile testing, 43.330 in shore D hardness test, and a density of 1.200 g/cm3 in density measurement. The findings suggest that PLA-carbon composites have the potential for enhanced performance in various industrial applications, particularly in sectors requiring improved physical and electrical properties.

Characteristics of Electrical Heating Elements Coated with Graphene Nanocomposite on Polyester Fabric: Effect of Different Graphene Contents and Annealing Temperatures

김혜림,이선희 한국섬유공학회 2018 Fibers and polymers Vol.19 No.5

This paper reports the fabrication of electrical heating elements based on the graphene/waterborne polyurethane (WPU) composite coated on polyester fabric with toughness like that of artificial leather. Samples were prepared with 0, 4, 8, and 16 wt% of graphene by using the knife edge method, and then, the samples were annealed from 100 oC to 160 oC. The graphene content had a large effect on the electrical and electrical heating properties. The surface resistivity was decreased by approximately 6 orders of magnitude with an increase from 0 wt% to 16 wt% graphene/WPU composite fabric. The electric heating properties were also improved, as indicated by the percolation threshold. Samples with various graphene contents were annealed, and it was found that the electrical and electrical heating properties were improved, and the most enhanced properties were obtained when the samples were annealed at 120 oC. The initial modulus and tensile strength were increased in comparison with those of 0 wt% and 16 wt% graphene/WPU composite coated on fabrics, but the elongation at break value was slightly decreased with an increasing graphene content. When the samples were annealed, initial modulus and tensile strength of samples were improved at 120 oC and 140 oC, and they were slightly decreased at 160 oC. However, the elongation at break showed an opposite tendency to the tensile strength. With the increase in content of graphene and annealing at 120 oC and 140 oC, the samples were more stiff and tough, and at 160 oC, the samples were softer. Therefore, graphene/WPU composite coated on polyester fabric by use of the annealing process may have applications in electrical heating elements due to its excellent heating performance and toughness like that of artificial leather.

민법의 물건과 형법의 재물개념의 상호관계에 관한 연구 -민사법과 형사법의 통일적 해석을 중심으로-

김성수 ( Seong Soo Kim ) 한국경찰법학회 2007 경찰법연구 Vol.5 No.2

The most immediate purpose of my paper is to furnish the logical and correlational interpretation between the definition of Things in the Korea Civil Code(KCC) and that of Property in the Korea Penal Code(KPC),moreover between Natural force(KCC article 98) and Energy(KPC article 346). In connection with this issue,the paper begins first by posing problems of terms between of Things in the KCC(article 98) and of Property in the KPC(article 329),which will be solved by studying of their historical background and comparative study. Next,we should note that Property in the KPC is meant by corporeal and incorporeal things,which is same to natural force in the KCC. Nonetheless two diffrent penal perspectives about its meaning,one is Corporeality theory and the other is Controllability theory. Historycally the penal code is directly from Japanese Penal Code(article 235) with its expansive application (from electricity to energy which is subject to human control)(KPC article 98), which is also the addition of the Japanese Civil Code defining the things meant by the corporeal things and electricity deemed to be property. By contrast,things in the KCC is more original in defining things mentioned in this law as corporeal things, electricity, and other natural force which can be controlled. So it is impossible to be interpretated with coherence of these articles,which are historically contradictory. De lege ferenda, we propose that the property in the article 329(larceny) of the KPC is to be interpreted according to aritcle 98 (Definition of Things) of the KC C,which is included corporeal things and incorporeal things. The illustrational term "electricity" in KCC,which is seems to inutile to us, comes historically of the amendment of the JPC,which includes only corporeal things,so it is discussed about the punishment of Larceny of electricity between scholors,is solved by adding to its orginal article. In the next section,we discussed whether the immovables(real estate) is included in the definition property, which is being a heated controversy, on the contrary is accepted natural in the civil law scholors. To us,who thinks the definition in the penal sense and in the civil sense,is to be interpreted as same, it is quite clear that the immovables,with the movable property, are naturally included. There remains a range of problems to be tackled,potential deficiencies in this topic of this paper,which is due entirely to me,but it is also hoped that this paper will serve as a platform of the interdisciplinary study between the civil law and the penal law, which studies of greater depth and specificity in this field may be undertaken.

Electrical Properties of a High Tc Superconductor for Renewed Electric Power Energy

Lee Sang-Heon The Korean Institute of Electrical Engineers 2006 Journal of Electrical Engineering & Technology Vol.1 No.3

Effects of $Ag_2O$ doping on the electromagnetic properties in the BiSrCaCuO superconductor. The electromagnetic properties of doped and undoped $Ag_2O$ in the BiSrCaCuO superconductor were evaluated to investigate the contribution of the pinning centers. It was confirmed experimentally that a larger amount of magnetic flux was trapped in the $Ag_2O$ doped sample than in the undoped one, indicating that the pinning centers of magnetic flux are related closely to the occurrence of the magnetic effect. We have fabricated superconductor ceramics by the chemical process. A high Tc superconductor with a nominal composition of $Bi_2Sr_2Ca_2Cu_3O_y$ was prepared by the organic metal salts method. Experimental results suggest that the intermediate phase formed before the formation of the superconductor phase may be the most important factor. The relation between electromagnetic properties of Bi HTS and the external applied magnetic field was studied. The electrical resistance of the superconductor was increased by the application of the external magnetic field. But the increase in the electrical resistance continues even after the removal of the magnetic field. The reason is as follows; the magnetic flux due to the external magnetic field penetrates through the superconductor and the penetrated magnetic flux is trapped after the removal of the magnetic flux. During the sintering, doped $Ag_2O$ was converted to Ag particles that were finely dispersed in superconductor samples. It is considered that the area where normal conduction takes place increases by adding $Ag_2O$ and the magnetic flux penetrating through the sample increases. The results suggested that $Ag_2O$ acts to amplify pinning centers of magnetic flux, contributing to the occurrence of the electromagnetic properties.

Electrical and Mechanical Properties of Carbon/Glass Hybridized Long Fiber Reinforced Polypropylene Composites

이동우,마성원,이기윤 한국고분자학회 2013 Macromolecular Research Vol.21 No.7

The electrical percolation and hybrid effect that forms from long carbon fiber (LCF) and long glass fiber (LGF) hybridized composite in a polypropylene matrix were studied by investigating electrical and mechanical properties. As a process, the electrical and mechanical properties were investigated in terms of LCF loading at constant volume percentage in the total. The electrical resistivities of volume and surface were measured in order to learn the percolation threshold points, which were 8-9 and 10-12 volume percents of LCF loading individually. The mechanical properties, such as, were tensile and flexural modulus of the hybridized composite were obtained and compared with the prediction results using the rule of hybrid mixtures (RoHM) equation. The hybrid effect was observed in the result of the tensile modulus in the range of 6-10 volume percent of LCF loading whereas there was no hybrid effect in flexural modulus. The tensile and flexural strengths of LCF/LGF hybridized composite are 100and 140MPa at 20 vol% of LCF loading. The tensile and flexural modulus are approximately 22 and 14 GPa at 20 vol%of LCF. The interaction between reinforced fiber and the matrix was reported and analyzed by scanning electron microscopy (SEM) and heat depletion temperature (HDT). Through the process, the mechanical strength was more related to the interaction between fiber and the polypropylene matrix than the mechanical modulus.

Electrical Properties of a High Tc Superconductor for Renewed Electric Power Energy

Sang-Heon Lee 대한전기학회 2006 Journal of Electrical Engineering & Technology Vol.1 No.3

Effects of Ag₂O doping on the electromagnetic properties in the BiSrCaCuO superconductor. The electromagnetic properties of doped and undoped Ag₂O in the BiSrCaCuO superconductor were evaluated to investigate the contribution of the pinning centers. It was confirmed experimentally that a larger amount of magnetic flux was trapped in the Ag₂O doped sample than in the undoped one, indicating that the pinning centers of magnetic flux are related closely to the occurrence of the magnetic effect. We have fabricated superconductor ceramics by the chemical process. A high Tc superconductor with a nominal composition of Bi₂Sr₂Ca₂Cu₃Oy was prepared by the organic metal salts method. Experimental results suggest that the intermediate phase formed before the formation of the superconductor phase may be the most important factor. The relation between electromagnetic properties of Bi HTS and the external applied magnetic field was studied. The electrical resistance of the superconductor was increased by the application of the external magnetic field. But the increase in the electrical resistance continues even after the removal of the magnetic field. The reason is as follows; the magnetic flux due to the external magnetic field penetrates through the superconductor and the penetrated magnetic flux is trapped after the removal of the magnetic flux. During the sintering, doped Ag₂O was converted to Ag particles that were finely dispersed in superconductor samples. It is considered that the area where normal conduction takes place increases by adding Ag₂O and the magnetic flux penetrating through the sample increases. The results suggested that Ag₂O acts to amplify pinning centers of magnetic flux, contributing to the occurrence of the electromagnetic properties.

충격보강제가 보강된 PPS (polyphenylene sulfide)/MWCNT (multi-walled carbon nanotube) 나노복합체의 물성연구

박지수,남병욱,김승범 한국반도체디스플레이기술학회 2012 반도체디스플레이기술학회지 Vol.11 No.2

Polymer composites which have electrical properties have been studied in various industries. The Multi-walled carbon nanotube (MWCNT) are thought to be reinforcements for polymers because of their high aspect ratio and specially mechanical, thermal and electrical properties. We introduced MWCNT and impact modifier in order to improve thermal and mechanical properties of Polyphenylene sulfide (PPS) and give electric characteristic to PPS. The thermal properties were investigated by Differential scanning calorimeter (DSC) and Thermogravimetric analysis (TGA). The morphology, mechanical properties and electrical characteristic were performed by Field emission scanning electron microscopy (FE-SEM), Izod impact tester and surface resistance meter. As a result, we could find that the PPS/MWCNT composites have high conductivity and good mechanical properties than neat PPS resin.

Structural, Electrical and Multiferroic Properties of Nb-doped Bi7Fe3Ti3O21 Thin Films

라그하반,김진원,김상수 한국물리학회 2015 새물리 Vol.65 No.6

The effects of donor Nb5+-ion doping on the structural, electrical, and multiferroic properties of an Aurivillius Bi7Fe3Ti3O21 thin film were investigated. Incorporation of Nb5+-ions into the Ti4+-sites of the Bi7Fe3Ti3O21 thin film resulted in a substantial improvement of its electrical and multiferroic properties. From the study of the electrical properties, the Bi7Fe3Ti2.94Nb0.06O21+δ thin film exhibited a low leakage current density of 5.11×10−6 A/cm2 at 100 kV/cm, which was about one order of magnitude lower than that of the untreated Bi7Fe3Ti3O21 thin film. The ferroelectric P −E hysteresis loops of the Bi7Fe3Ti2.94Nb0.06O21+ thin film showed a large remnant polarization (2Pr) of 20.6 μC/cm2 at 630 kV/cm whereas the 2Pr value measured for the untreated Bi7Fe3Ti3O21 thin film was 3.5 μC/cm2 at 318 kV/cm. Furthermore, a well-saturated magnetic hysteresis loop with an enhanced magnetization was observed for the Bi7Fe3Ti2.94Nb0.06O21+δ thin film at room temperature.

고상 반응법에 의하여 합성된 $LiMn_2O_4$의 구조와 전기적 특성

오원춘,김범수,이영훈,고영신,Oh, Won-Chun,Kim, Bum-Soo,Lee, Young-Hoon,Ko, Young-Shin 한국분석과학회 1998 분석과학 Vol.11 No.5

We have studied structural characterization, electrical charge and discharge, and impedence properties for the $LiMn_2O_4$ synthesized by solid state reaction. From the X-ray diffraction results, diffraction patterns for compounds of the four kinds of $LiMn_2O_4$ compounds were observed to peaks of (111), (311), (004) and (400). Also, Small similar peaks (110), (222) and (313) were observed for sample C1 and C2. Concerning to new peaks of (113) and (331) for the sample C4, we can found that structural transitions were accompanied from C1 and C2 to C4 via C3 structure. A electrical charge and discharge data showed that efficiency of C1 was very poor state and efficiencies of C2 and C3 were about 60-70% of theoretical capacity. But, the C4 showed good charge and discharge properties of more than 70% of theoretical capacity. From the impedence properties for finding the effect of ions and electrons transfer of battery, C2 and C3 of high frequency of real number showed good electrical impedence properties. 고상 반응법에 의하여 합성된 $LiMn_2O_4$를 구조적인 특성과 전기적인 충방전 특성과 임피던스 특성에 대하여 연구하였다. X-선 회절 분석 결과에 의하면 4가지 형태의 화합물 모두가 $LiMn_2O_4$의 주요 회절선인(111), (311), (004)와 (400)이 모두 일치하여 나타났다. C1과 C2는 유사하게 (110), (222) 및 (313)의 회절선이 미소하게 나타났음을 알 수 있었다. C4의 경우는 (113)이나 (331)과 같은 새로운 회절선이 나타난 것으로 보아 C1과 C2의 구조에서 C3의 구조를 거쳐서 C4의 구조로 구조변환이 일어나는 과정임을 알 수 있었다. 전기적인 충방전 특성으로 부터 C1의 경우는 충전 방전 특성이 아주 저하된 상태를 나타내었으며, C2와 C3의 경우는 유사하게 나타났으나, 이들은 이론용량에 60-70%의 범위에 미치는데 그쳤다. 그러나 C4의 경우는 이론 용량의 70% 이상을 나타내는 좋은 충전 방전 특성을 나타냄을 알 수 있었다. 전지의 이온이나 전자 전달의 효과를 알아보기 위하여 임피던스의 특성으로부터 실수부의 파장이 높은 부근에서 형성된 C2과 C3의 경우는 비교적 좋은 특성을 보이고 있음을 알 수 있었다.