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강한 펄스자기장 자극에 의한 적혈구 연전현상의 활동성 조사
황도근(Do Guwn Hwang) 한국자기학회 2017 韓國磁氣學會誌 Vol.27 No.3
It is widely known that pulsed magnetic field (PMF) is very useful tool to manipulate chemical and physiological processes in human body. The purpose of our study is to observe dynamics of rouleaux patterns of red blood cells (RBC) under PMF. The aggregation of RBCs or rouleaux formation is caused by fibrinogen in blood plasma. The maximum magnetic field intensity is 0.27 T and pulse time of 0.102 msec and pulse repetition rate was 1 ㎐. PMF stimulus was applied to the palm of left hand for 5, 10, 15 and 20 min. Live blood analysis was used in vitro in order to quantitatively estimate the velocity of RBC exposed to PMF stimulus. The velocity of stacked-RBC of 10 minute PMF stimulus was increased up to 8 × 10<SUP>−4</SUP>m/sec, but it decreased rapidly as the time passed. The results of present study have adduced that PMF stimulus on hand provide the improvement of RBC rouleaux formation, increase of RBC’s moving velocity as well as low blood viscosity.
교류자기장 자극에 따른 인간 간암세포와 정상세포의 성장률 차이 연구
황도근(Do Guwn Hwang),박혜지(Hyeji Park) 한국자기학회 2020 韓國磁氣學會誌 Vol.30 No.5
The difference of proliferation rates between human liver cancer cells and normal liver cells stimulated by alternative magnetic field at the frequency of 1.5 kHz and the intensity of 0.5 mT during 48 hours in incubator were investigated. The proliferation rates of liver cancer cells stimulated by the magnetic field decreased up to 79%, but the rates of normal liver cells did not change in spite of the magnetic field stimulation. It is assumed that the alternative magnetic stimulation on the living cells can influence to the proliferation rates of liver cancer cells. In order to know the influence of ion channel on magnetic field in liver cell membrane, we should study to the frequency dependence of alternative magnetic field.
황도근(Do Guwn Hwang) 한국자기학회 2014 韓國磁氣學會誌 Vol.24 No.1
The change of rouleau formation of red blood cells in the hand stimulated by pulse magnetic field having a maximum intensity of 0.27 Tesla and pulse duration of 0.102 msec was investigated. Before pulse magnetic field stimulus, the red blood cells of test subject were adjoined over ten and the flow of cells was slowed. However after the stimulus in the hand during 10 minutes, the red blood cells adjoined over tens was spreaded out each other and its motion was fast. Also the red blood cells of left hand unstimulated by pulse magnetic field were spreaded out each other, even though the right hand was stimulated during 10 minute. It prove that the rouleau formation of red blood cells can be improve in the whole body in spite of stimulus in the hand because the blood is flowing a whole body.
비정질 n형 Si 박막을 이용한 자기터널링 트랜지스터 제작과 특성
이상석,이진용,황도근,Lee, Sang-Suk,Lee, Jin-Yong,Hwang, Do-Guwn 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.3
Magnetic tunneling transistor (MTT) device using the amorphous n-type Si semiconductor film for base and collector consisting of the [CoFe/NiFe](free layer) and Si(top layer) multilayers was used to study the spin-dependent hot electron magnetocurrent (MC) and tunneling magnetoresistance (TMR) at room temperature. A large MC of 40.2 % was observed at the emitter-base bias voltage ( $V_{EB}$ ) of 0.62 V. The increasing emitter hot current and transfer ratio ( $I_{C}$/ $I_{E}$) as $V_{EB}$ are mainly due to a rapid increase of the number of conduction band states in the Si collector. However, above the $V_{EB}$ of 0.62 V, the rapid decrease of MC was observed in amorphous Si-based MTT because of hot electron spin-dependent elastic scattering across CoFe/Si interfaces.
자성박막 소자 에칭용 전자 사이클로트론 공명 이온밀링 시스템 제작과 특성연구
이원형(Won-Hyung Lee),황도근(Do-Guwn Hwang),이상석(Sang-Suk Lee),이장로(Jang-Roh Rhee) 한국자기학회 2015 韓國磁氣學會誌 Vol.25 No.5
The ECR (Electron Cyclotron Resonance) Ar ion milling was manufactured to fabricate the device of thin film. The ECR ion milling system applied to the device etching operated by a power of 600W, a frequency of 2.45 GHz, and a wavelength of 12.24 cm and transferred by a designed waveguide. In order to match one resonant frequency, a magnetic field of 908 G was applied to a cavity inside of ECR. The Ar gas intruded into a cavity and created the discharged ion beam. The surface of target material was etched by the ion beam having an acceleration voltage of 1000 V. The formed devices with a width of 1 μm~9 μm on the GMR-SV (Giant magnetoresistance-spin valve) multilayer after three major processes such as photo lithography, ion milling, and electrode fabrication were observed by the optical microscope.
최종구(Jong-Gu Choi),황도근(Do-Guwn Hwang),이상석(Sang-Suk Lee),이장로(Jang-Roh Rhee) 한국자기학회 2009 韓國磁氣學會誌 Vol.19 No.4
The soft magnetic property for the Corning glass/Ta(5 ㎚)/[Conetic, Permalloy)/Ta(3 ㎚) prepared by the ion beam deposition sputtering was investigated. The coercivity and saturation magnetic field of conetic (NiFeCuMo) and permalloy (NiFe) layer with easy and hard direction along to the applying magnetic field during deposition was compared with each other. The surface resistance of conetic film with a thickness of 10 ㎚ was 2 times lower than one of permalloy film. The coercivity and the magnetic susceptibility of conetic film decreased and increased 3 times to one of permalloy film, respectively. These results suggest that a highly sensitive GMRSV or MTJ using conetic film can be possible to develop the bio-device.
NiFe/FeMn 이중박막의 증착시 자기장에 의한 교환결합력 이방성 효과
박영석(Young-Seok Park),황도근(Do-Guwn Hwang),이상석(Sang-Suk Lee) 한국자기학회 2008 韓國磁氣學會誌 Vol.18 No.5
The relation of ferromagnet anisotropic magnetization and the antiferromagnet atomic spin configuration has been investigated for variously angles of unidirectional deposition magnetic field of FeMn layer in Corning glas/Ta(5 ㎚)/NiFe(7 ㎚)/FeMn(25 ㎚)/Ta(5 ㎚) multilayer prepared by ion beam deposition. Three unidirectional deposition angles of FeMn layer are 0°, 45°, and 90°, respectively. The exchange bias field (H<SUB>ex</SUB>) obtained from the measuring easy axis MR loop was decreased to 40 Oe in deposition angle of 45°, and to 0 Oe in the angle of 90°. One other side hand, H<SUB>ex</SUB> obtained from the measuring hard axis MR loop was increased to 35 Oe in deposition angle of 45°, and to 79 Oe in the angle of 90°. Although the difference of uniderectional axis between ferromagnet NiFe and antiferromagnet FeMn was 90°, the strong antiferromagnetic dipole moment of FeMn caused to rotate the weak ferromagnetic dipole moment of NiFe in the interface. This result implies that one of origins for exchange coupling mechanism depends on the effect of magnetic field angle during deposition of antiferromgnet FeMn layer.
버퍼층 Ta에 의존하는 코네틱 박막의 연자성 자기저항 특성
최종구(Jong-Gu Choi),황도근(Do-Guwn Hwang),이상석(Sang-Suk Lee),최진협(Jin-Hyub Choi),이기암(Ky-Am Lee),이장로(Jang-Rho Rhee) 한국자기학회 2009 韓國磁氣學會誌 Vol.19 No.6
The property of soft magnetism for the Corning glass/non-buffer or buffer Ta/Conetic(NiFeCuMo)/Ta prepared by the ion beam deposition sputtering was studied. The effect of crystal property and post annealing treatment depending on the thickness of Conetic thin films was investigated. The coercivities of Conetic thin films with easy and hard direction along to the applying magnetic field during deposition were compared with each other. The coercivity and magnetic susceptibility of Ta(5 ㎚)/Conetic(50 ㎚) thin film were 0.12 Oe and 1.2 × 10⁴, respectively. From these results, firstly, the Conetic thin film was more soft magnetism thin film than other one such as permalloy NiFe. Secondly, the usage of soft magnetism Conetic thin film for GMR-SV (giant magneoresistance-spin valve) or MTJ (Megnetic Tunnel Junction) structure in a low magnetic field can be possible.
Si₃N₄ 장벽층을 이용한 경사형 모서리 접합의 터널링 자기저항 특성
김영일(Young-Il Kim),황도근(Do-Guwn Hwang),이상석(Sang-Suk Lee) 한국자기학회 2002 韓國磁氣學會誌 Vol.12 No.6
The tunneling magnetoresistance (TMR) of a ramp-edge type junction has been studied. The samples with a structure of NiO(60)/ Co(10)/NiO(60)/Si₃N₄(2-6)/NiFe(10) (㎚) were prepared by the sputtering and etched by the electron cyclotron (ECR) argon ion milling. Nonlinear I-V characteristics was obtained from a ramp-type tunneling junctions having the dominant difference between zero and +90 Oe perpendicular to the junction edge line. The voltage dependence of TMR was stable up to a bias volt of ±10 V with a TMR ratio of about -10%, which may be very peculiar magnetic tunneling properties with asymmetric tunneling process between wedge Co pinned layer and NiFe free layer.