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盧泰完,高鳳煥 弘益大學校 科學技術硏究所 1997 科學技術硏究論文集 Vol.8 No.-
In some classes of radiative and neutron transport problems that include strongly diffusing media, it might be impractical to refine the mesh enough to enter the regime of thin mesh cells. This is because such media are too optically thick to realistically allow sufficient mesh refinement. Considering that the simplified even-parity neutron transport equation is an approximation to the Boltzmann and even-parity transport equation, it is advantageous if the method has the correct diffusion limit; in other words, it gives generally accurate results in diffusing regimes, even when mesh cells are not thin. Our asymptotic analyses have shown that the so-called thick diffusion limit is satisfied by the finite element even-parity and simplified even-parity transport equations.
낮은 큐리온도를 가진 Fe-Ni-Zr 비정질 합금의 저온 구조완화와 자기적 특성
노태환 국립7개대학공동논문집간행위원회 2001 공업기술연구 Vol.1 No.-
The coercive force(H_c), ac permeability(μ_ac), and remanence(B_r) as a function of annealing temperature for metal-metal type (Fe_0.85Ni_0.15)_90Zr_10 amorphous alloy with low T_c(= 412 K) were measured, and temperature dependence of an enthalpy relaxation was examined. The increase in H_c and decrease in μ_ac and B_r were observed at the annealing temperature ranging from 425 to 550 K, where the low temperature enthalpy relaxation originated from Fe-Ni interactions occurred. Thus the degradation of soft magnetic properties was attributed to local-ranged Fe-Ni atom regroupings enhancing the structural heterogeneity and probably causing the non-uniform internal stresses.
Fe-(89-x)Hf-(x)B-(11) 비정질 합금의 자기적 특성
노태환 安東大學校 工業技術硏究所 2001 공업기술연구논문집 Vol.8 No.1
Fe_(89-x)Hf_(x)B_(11) (at%) 비정질 합금의 자기적 특성과 결정화 온도에 미치는 Hf의 영향을 조사하였다. Hf의 농도를 5~10at%의 범위에서 변화시킬 경우, 약 7at%의 조성 부근에서 가장 높은 실효투자율과 가장 낮은 보자력을 나타내고 동시에 최소의 고주파 자심손실이 얻어졌다. 그리고 Hf을 증가시키면 포화자기변형이 감소하여 연자성 및 교류자화 특성의 향상에 대한 원인을 제공하는 것으로 밝혀졌으며, 결정화온도가 증가하여 보다 높은 열적 안정성이 얻어지는 것으로 관찰되었다. 포화자속밀도는 Hf증가에 따라 감소하였으나 그 정도는 그리 크지 않았으며 Hf=7at%에서 대략 10kG의 값을 나타내었다. 결국 Hf이 7at% 정도 되는 조성에서 양호한 연자성과 적절한 자화의 크기를 가지면서 우수한 고주파 자심손실 특성이 함께 얻어짐을 알게 되었다. The effects of Hf on the magnetic properties and crystallization temperature of Fe_(89-x)Hf_(x)B_(11) (x=5~10)(at%) amorphous alloys were investigated. At the concentration of x=7, the highest effective permeability, lowest coercive force and high-frequency core loss were observed. Further, saturation magnetostriction decreased with increasing the Hf content, which was considered to give rise to improvement of the soft magnetic properties and a.c. magnetization characteristics. Moreover crystallization temperature increased with the Hf content, and then higher thermal stability resulted. The Hf decreased the saturation magnetization of the alloys, however the amount of decrease was not so large. The value of Bio of the alloy having 7at% Hf was about 10 kG. In consequence, good soft magnetic properties, moderate magnetization and excellent core-loss properties at high frequency were obtained in the alloy with optimum Hf content (x=7).
Relation between Disease Incidence of Bacterial Grain Rot of Rice and Weather Conditions
Noh,Tae-Hwan,Kim,Hyung-Moo,Song,Wan-Yeob,Lee,Du-ku,Kang,Mi-Hyung,Shim,Hyeong-Kwon 한국자원식물학회 2004 Plant Resources Vol.7 No.1
Bacterial grain rot of rice caused by Burkholderia glumae was examined between weather condition and disease incidence. From 1998 to 2000, average disease incidence was 3.0 % without difference in survey regions. However, it was related closely to amount of rainfall that disease incidence higher in 1998 and 2000 to 3.0 % and 3.6 % respectively than 2.3 in 1999 relatively small volum of rainfall season.
부유대역 용융응고법으로 제조된 YBa_2Cu_3O_x 산화물초전도체의 미세구조와 전기적 특성
노태형,송정환,장규철,한이섭,김소정,구본급,김호기 대전산업대학교 반도체기술연구소 2000 半導體技術硏究所報 Vol.2 No.-
The YBa_2Cu_3O_x-20 wt% Y_2BaCuO_5 composition designed in YBCO system was synthesized by solid state reaction method. The optimum condition of hot zone temperature and growth rate in floating-zone melt were 1080 ℃ and 2.5 mm/hour, respectively. In samples growth as these condition, the low angel boundaries in grain direction and small amount of amorphous phase known as decreasing characteristics of superconducting materials between grain boundaries in microstructure are investigated by polarized light microscopy on the whole. The critical current density(Jc) at 77k of sample using powder fabricated with no CeO_2 and doped 5 wt%CeO_2 were 8,000 A/㎠(Jc : 561A) and 12,000 A/㎠(Jc: 826A) at 0 T by direct current transport method, respectively.
Fe_(73.5)Cu₁Nb₃Si_(13.5)B_(9) 초미세 결정립 합금의 분말코아 특성
노태환,최혁열 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.6
The melt-spun Fe_(73.5)Cu₁Nb₃Si_(13.5)B_(9) ribbons so called Finemet alloy were annealed in the temperature range of 490 to 610℃ for 1 h and milled by using a planetary ball mill into the powders with the size of 250~850 sm. Then the powder cores were produced through the blending of the magnetic powders with the 5 wt% of ceramic insulator and cold compaction. Further the annealing responses of magnetic, electrical properties and microstructure were investigated. At the annealing temperature of 550℃, the microstructure was transformed from amorphous to crystalline a-Fe phase with the grain size of 10.7 nm, and the electrical resistivity of 117 μΩ-㎝ was obtained. At the same time, the effective permeability and quality factor reached 120 and 50, respectively, and the permeability persisted up to about 500 kHz. Moreover the core loss at the frequency of 50 kHz and the magnetic induction of 0.1 T was about 300 mW/cm³. These magnetic properties were comparable to the conventional powder core materials such as MPP(molybdenum permalloy powder), Sendust etc. However the dc bias characteristics represented by the permeability stability upon dc magnetic field superposition were found to be unsatisfactory. (Received February 16, 2004)
인산염 피막처리 분말을 사용한 철계 나노결정합금 분말코아의 자기적 특성에 미치는 인산농도의 영향
김영민,노태환 국립7개대학공동논문집간행위원회 2005 공업기술연구 Vol.5 No.-
Phosphate coating to the FeCuNbSiB nanocrystalline alloy powders for electrical insulation has been carried out in aqueous solutions with different phosphoric acid concentrations, and the surface-treated powders were cold-compressed into the powder cores. In the solutions with higher acid concentration, the more phosphatized surface was obtained. The powder cores using phosphate-coated powders in the solution with 2.0 wt% H₃PO₄ exhibited effective permeability of 95 up 500kHz and core loss of 380 mW/cm3 at 50kHz/0.1 T. The effective permeability and core loss had a tendency to decrease with increasing the acid concentration. These indicate that the formation of larger quantity of phosphates on the surface could provide more effective electrical insulation between magnetic nanocrystalline powders.
Tae Hwan Noh 사단법인 한국질량분석학회 2023 Mass spectrometry letters Vol.14 No.3
The reaction of (COD)PdCl 2 with new C 3 -symmetric tridentate L (COD = 1,5-cyclooctadien; L = 1,3,5- tris(picolinoyloxyethyl)cyanurate) in a mixture of acetone and dichloromethane produces single crystals consisting of unprecedented monometallacyclic [PdCl 2 (L)]. This cyclic compound arises from trans-chelation of two of three donating pyridyl groups of L, while the third pyridyl group remains uncoordinated. Electrospray ionization mass spectrometry (ESI-MS) data on L exhibited the major peak corresponding to [C 27 H 24 N 6 O 9 + H + ] + . Fast atom bombardment mass spectrometry (FAB- MS) data on [PdCl 2 (L)], however, showed the mass peak corresponding to the L instead of the present palladium(II) compound species, due to the insolubility and dissociation in solution. The physicochemical properties of the present palladium(II) compound were fully characterized by means of infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy, thermal analysis, single-crystal X-ray diffraction (SC-XRD) measurement.