http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
홍순철(Soon Cheol Hong),엇후(Dorj Odkhuu) 한국자기학회 2019 韓國磁氣學會誌 Vol.29 No.4
Since Nd₂Fe<SUB>14</SUB>B permanent magnet was developed in 1982, a new permanent magnet with higher performance than Nd2Fe14B has not been reported yet. On the other hand, new permanent magnet materials, which do not include rare-earth elements but are competible to ferrites in price, also are needed to be searched urgently. In this paper, we will review required material properties for good permanent magnets and discuss ways to search new permanent magnets, using first principles calculations. The goal to search the new permanent magnets should be set to find materials to have higher performance than Nd₂Fe<SUB>14</SUB>B or to be consisted of 3d transition metal as magnetic elements with compatible performance to Nd₂Fe<SUB>14</SUB>B to replace high performance rare-earth magnets or cheap ferrites.
홍순철(Soon Cheol Hong) 한국자기학회 2016 韓國磁氣學會誌 Vol.26 No.1
Pd has the highest magnetic susceptibility among single element metals and often shows ferromagnetism under some special environments. In this paper, we report magnetism of 5- and 9-monolayers (ML) calculated by using full-potential linearized augmented plane wave method. Exchange-correlation interaction is taken into account in local density approximation (LDA) and generalized gradient approximation (GGA) and calculational results in LDA and GGA are compared with each other. It is found that calculations by LDA are more reliable compared to those by GGA because LDA prediction of paramagnetism of bulk Pd is consistent with experiments, whereas GGA predicts wrongly ferromagnetim of bulk Pd. Calculational results in LDA on a 5-ML Pd(111) thin film shows a ferromagnetic ground state unlike a paramagnetic ground state of bulk Pd. The center Pd layer of the 5-ML Pd(111) thin film has the largest magnetic moment (0.273 μB) among the layers and |m| = 1 orbital states play a dominant role in stabilizing the ferromagnetism of the 5-ML Pd(111) thin film. A 9-ML Pd(111) thin film in a ferromagnetic state has almost the same total energy as in a paramagnetic state. Since the magnetization of the 9-ML Pd(111) thin film is stable, the ferromagnetic state may be meta-stable.
시장경쟁력이 있는 새로운 영구자석 소재 탐색을 위한 제일원리계산
홍순철(Soon Cheol Hong),Odkhuu 한국자기학회 2024 韓國磁氣學會誌 Vol.34 No.4
1952년에 개발되기 시작한 페라이트 자석는 가격 경쟁력이 있고 1984년에 개발된 네오디뮴 자석은 성능이 최고이어서 현재 영구자석 시장을 압도적으로 양분하고 있다. 성능은 페라이트 자석의 (BH)max는 대략 4.0 MGOe이고 네오디뮴 자석은 대략 50 MGOe으로 성능은 약 10 배정도 낮지만 가격 경쟁력(2016년 기준으로 약 15 배 낮은)을 갖추고 있다. 본 논문에서는 시장 경쟁력을 염두에 두고 새로운 영구자석 소재를 제안하기 위해 제일원리계산 방법으로 할 수 있는 일을 정리해 보았다. 시장 경쟁력을 위해서는 소재의 성능지수가 높아야 하는 것은 기본이고, 가격, 공정 용이성, 온도 특성이 우수하여야 한다. 네오디뮴 자석보다 성능이 우수한 영구자석 소재가 가능한지, 공급망 문제가 있는 희토류 원소를 포함하지 않으면서 페라이트 영구자석 보다 성능이 우수하고 가격 경쟁력도 있는 비희토류 영구자석 소재가 가능한지에 대해 이야기하고자 한다. The permanent magnet market is currently dominated by ferrite and neodymium magnets. The former, developed in 1952, are competitively priced, while the latter, developed in 1984, show the highest performance. In terms of performance, neodymium magnets have a (BH)max of about 50 MGOe, which is more than 10 times higher than that of ferrite magnets (about 4.0 MGOe). However, in terms of price, ferrite magnets are advantageous as they will be about 15 times less expensive than neodymium magnets by 2016. In this paper, we discuss what can be done with the first-principles calculation method to propose new permanent magnet materials with a focus on market competitiveness. To be competitive in the marketplace, the material must have not only high performance, but also excellent price, ease of processing, and temperature characteristics. I would like to discuss the possibility of creating a permanent magnet material that outperforms neodymium magnets, or a non-rare earth permanent magnet material that outperforms ferrite permanent magnets without containing rare earth elements that have supply chain issues, while competing on price.
제일원리계산에 의한 단층 MoS₂ 의 1H/1T 경계 자성
제갈소영(Soyoung Jekal),홍순철(Soon Cheol Hong) 한국자기학회 2016 韓國磁氣學會誌 Vol.26 No.3
Monolayer MoS₂ is energetically most stable when it has a 1H phase, but 1H to 1T phase transition (1H→1T) is easily realized by various ways. Even though magnetic moment is not observed during 1H→1T, 0.049 μ<SUB>B</SUB>/MoS₂ is obtained in local 1T phase; 75% 2H and 25% 1T phases are mixed in (2 × 2) supercell. Most magnetic moment is originated from the 1T phase Mo atom in the supercell, while the magnetic moments of other atoms are negligible. As a result, magnetic/non-magnetic boundary is created in the monolayered MoS₂. Our result suggests that MoS₂ can be applied for spintronics such as a spin transistor.
Ni/Fe(001)의 자성과 자기이방성에 대한 제일원리계산
권오룡(Oryong Kwon),홍순철(Soon Cheol Hong) 한국자기학회 2015 韓國磁氣學會誌 Vol.25 No.4
Recent theoretical calculations predicted that a system composed exclusively of 3d transition metals without 4d/5d transition metals or rare earth metals can have strong perpendicular magnetocrystalline anisotropy (MCA) if Fe and Ni layers are arranged appropriately. They considered only Fe-terminated surfaces, noting that Fe/MgO(001) and CoFeB/MgO(001) show strong perpendicular MCA. In this paper, we investigate magnetism and MCA of Ni/Fe(001) surface where Ni layer is positioned at the surface, by using complementarily the first principles calculational methods of Vienna Ab-initio Simulation Package (VASP) and Fullpotential Linearized Augmented Plane Wave (FLAPW) method. Comparing results of magnetism and MCA obtained by VASP with the results by FLAPW method, we find the VASP results do not show big difference from results by FLAPW method. Magnetic moments of Fe and Ni are enhanced due to strong hybridization between Fe and Ni bands. MCA of Ni/Fe(001) is parallel to the surface, which implies the surface termination plays a crucial role in determining MCA of a system.
신생아의 제대 혈액 및 산모의 혈액내 adiponectin 농도와 신생아의 체중과의 연관성에 관한 연구
조금준 ( Geum Joon Cho ),홍순철 ( Soon Cheol Hong ),유상욱 ( Sang Wook Yoo ),오민정 ( Min Jeong Oh ),김탁 ( Tak Kim ),김해중 ( Hae Joong Kim ),강재성 ( Jae Seong Kang ),이규완 ( Kyu Wan Lee ),나중열 ( Jung Yeol Na ),김선행 ( Sun 대한산부인과학회 2005 Obstetrics & Gynecology Science Vol.48 No.11