• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
• /
• pp.98-99
• /
• 2003

• 한국가시화정보학회:학술대회논문집
• /
• 한국가시화정보학회 2003년도 추계학술대회 논문집
• /
• pp.55-58
• /
• 2003

In this paper the numerical method with a zonal embedded grid system for an incompressible flow within a circular container is presented. The algorithm is validated by its application to some typical flow models including the spin-up flow inside a half-circle geometry.

• Journal of Magnetics
• /
• 제7권3호
• /
• pp.80-93
• /
• 2002

The role of magnetic anisotropy of the antiferromagnetic layer on the magnetization process of exchange coupled polycrystalline ferromagnetidantiferromagnetic bilayers is discussed. In order to elucidate the magnetic torque response of Ni-Fe/Mn-Ir bilayers, the single spin ensemble model is newly introduced, taking into account the two-dimensionally random distribution of the magnetic anisotropy axes of the antiferromagnetic grains. The mechanism of the reversible inducement of the exchange anisotropy along desirable directions by field cooling procedure is successfully explained with the new model. Unidirectional anisotropy constant, J$k$, of polycrystalline Ni-Fe/Mn-Ir and Co-Fe/Mn-Ir bilayers is investigated as functions of the chemical composition of both the ferromagnetic layer and the antiferromagnetic layer. The effects of microstructure and surface modification of the antiferromagnetic layer on JK are also discussed. As a notable result, an extra large value of J$k$, which exceeds 0.5 erg/cm$^2$, is obtained for $Co_{70}Fe_{30}Mn_{75}Ir_{25}$ bilayer with the ultra-thin (50${\AA}$∼100${\AA}$) Mn-Ir layer. The exchange anisotropy of $Co_{70}Fe_{30}$ 40 ${\AA}/Mn_{75}Ir_{25}$ 100 ${\AA}$ bilayer is stable for thermal annealing up to $400{^{\circ}C}$, which is sufficiently high for the application of spin valve magnetoresistive devices.

• Nuclear Engineering and Technology
• /
• 제2권4호
• /
• pp.241-248
• /
• 1970

Karlsruhe 3 MeV pulsed Van do Graaff 사용 중성자비행시간법으로 농축된 동위원소 들의 중성자 전단면적을 측정하였다. 중성자 에너지 영역은 10kev로부터 250keV이며 에너지 분해능은 0.2와 0.5 nsec/m 사이이다. 측정된 전단면적은 R-matrix. multi-level formula로 shape-analysis를 했다. 각 원소당 50주 가까운 공조에 대하여 중성자폭과 Spin을 결정할 수 있었다. 평균중성자폭, 준위밀도, Strength function도 결정하였다. Strength function의 Spin의존성, 중성자폭분포 및 준위간 간격도 함께 규명하였다.

• 한국자기학회지
• /
• 제1권2호
• /
• pp.55-59
• /
• 1991

희토류-3d 천이원소인 비정질${[{(Fe_{80}CO_{20})}_{0.98}RE_{0.02}]}_{80}B_{20}(RE=Nd,\;Sm,\;Gd,\;Tb)$ 합금 리본시료에 대한 자기적 성질을 조사하기 위하여 시료진동형 자력계(vibrating sample magnetometor)를 이용하여 77 K부터 900 K까지의 온도 영역에서 포화자화 값을 온도의 함수로 측정 한후, Curie 온도 ($T_{c}$)와 Bloch 상수등을 추정하였다. 이들로 부터 spin wave stiffness 상수, 교환상호작용(exchange interaction)의 범위와 평균자승거리($$)등을 계산하였으며 각 희토류 원소에 대한 치환효과를 비교 분석하였다.

• 한국군사과학기술학회지
• /
• 제18권6호
• /
• pp.728-735
• /
• 2015

A gas gun system to replicate the flight motions of large caliber spin-stabilized ammunition has been investigated experimentally and numerically. The system is specially designed to study aerodynamic characteristics and dynamics of a flight body ejected from a cargo shell or a subsonic projectile itself at up to 2,000 rpm and 100 m/s. Raynolds-averaged Navier-Stokes equations with a overset mesh technique and 6-DOF dynamics were solved to decide the chamber pressure according to the muzzle velocity input by users. The predicted velocity values show less than 6 % of discrepancies compared to experimental data. The system has successfully been tested for the simulation of deployment of a parafoil for a 155 mm gun-launched projectile.

• 한국응용과학기술학회지
• /
• 제14권1호
• /
• pp.53-59
• /
• 1997

Spin finish(NSFs) for synthetic fiber were prepared. NSF-3 was proved to be the best spin finish by testing the properties and emulsion stability, etc. of NSFs. NSF-3 prepared by blending of spindle oil 70g, paraffin wax 10g, glyceryl mono-oleate 5g, POE(10) nonylphenyl ether 4g, POE(20) sorbitan tri-oleate 4g, Na-dioctyl sulfosuccinate 4g, antistatic agent 2g and water 1g was excellent in its characteristics. Optimum physical conditions of nylon filament treated with NSF-3 according to the number of revolution of oil roller were obtained at conditions of 5.5rpm in the number of revolution of oil roller, 1.21% of oil pick up, and denier 69.2D.

• 한국자기학회지
• /
• 제27권4호
• /
• pp.145-152
• /
• 2017

동맥스핀표지 기법(ASL)은 체내의 혈액을 이용하여 조직의 관류상태를 평가할 수 있는 자기공명영상 방법이다. 조영제를 사용하지 않는 비침습적 검사 특성과 정량적인 관류량의 측정이 가능하여 임상이나 연구목적으로 이용 빈도가 증가하고 있다. 아직까지는 ASL 방법이 조영제를 이용한 관류영상 방법에 비해 낮은 SNR과 영상화 과정에서의 여러 가지 변수의 최적화 과정이 어렵기 때문에 이로 인한 측정오차가 발생할 수 있다. 이를 개선하기 위해 다양한 기술을 적용한 ASL 방법들이 소개되고 있다. 본 논문은 ASL의 개요와 영상화 과정에서의 특징 및 다양한 기술, 임상적 적용에 대해 간단히 소개한다.

• Bulletin of the Korean Chemical Society
• /
• 제29권3호
• /
• pp.623-626
• /
• 2008

Spin-coating electrostatic self-assembly (SCESA) is utilized to fabricate a single layer of carboxylic-acid-coated Pd nanoparticles (NPs) (D??5 nm) on an oppositely charged surface. The packing density of a NP monolayer formed on a rotating solid substrate (3000 rpm) was examined with regards to various parameters, including the particle concentration, the pH, and the ionic strength of the solution. Initially, the packing density grew exponentially with increases in the particle concentration, up to a maximum value (of 8.4 ´ 1011/cm2) at 1.2 wt%. The packing density was also found to increase drastically as the pH decreased and the ionic strength of the solution increased; these trends can be attributed to a reduction in the interparticle repulsions among the NPs in the solution and on the substrate. The best result of this study was achieved in a 1.2 wt% solution at pH 8; under these conditions, an NP monolayer with the highest density (namely, 1.6 ´ 1012/cm2) was obtained.

• Journal of Astronomy and Space Sciences
• /
• 제33권4호
• /
• pp.295-304
• /
• 2016

The atmosphere strongly affects the Earth's spin rotation in wide range of timescale from daily to annual. Its dominant role in the seasonal perturbations of both the pole position and spinning rate of the Earth is once again confirmed by a comparison of two recent data sets; i) the Earth orientation parameter and ii) the global atmospheric state. The atmospheric semi-diurnal tide has been known to be a source of the Earth's spin acceleration, and its magnitude is re-estimated by using an enhanced formulation and an up-dated empirical atmospheric S2 tide model. During the last twenty years, an unusual eastward drift of the Earth's pole has been observed. The change in the Earth's inertia tensor due to glacier mass redistribution is directly assessed, and the recent eastward movement of the pole is ascribed to this change. Furthermore, the associated changes in the length of day and UT1 are estimated.