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정보과학(情報科學)의 기초(基礎) : 제1부 - 그 철학적(哲學的) 측면(側面) -
Brookes, Bertram C. 한국과학기술정보연구원 과학기술정보센터 1983 Journal of Information Science Theory and Practice Vol.16 No.4
여타 다른 학문분야에서 주장되지 않는 정보과학(情報科學)에 대한 정립(定立)은 Kari Popper의 제 3 세계 - 객관적(客觀的) 지식(知識)의 세계(世界) - 고도(高度)의 자율성(自律性)을 인정함으로써 발견 될 수 있다는 것을 우선적으로 논의하게 된다. 따라서 정보과학의 임무란 객관적(客觀的) 지식(知識)의 세계(世界)를 탐구(探究)하는 것으로 정의(定議)를 내릴 수 있으며, 또한 도큐멘테이션과 도서관학의 영역을 확대시키는 것도 되지만, 양자(兩者)는 분명히 구별되어야 한다. Popper 식(式)의 존재론은 정보(情報) 개념(槪念) 및 주관적(主觀的) 객관적(客觀的) 지식(知識)들과의 관계가 확대되어 수용되어져야 한다. 그리하여 Popper의 세가지 세계의 공간영역들은 고찰(考察)의 대상이 된다. 인식과 물리적인 공간은 동일(同一)하지 않으며, 이러한 동일성(同一性)의 결여가 정보현상에 대한 적절한 정량화(定量化)를 저지시키는 문제를 발생케하는 요인이 된다고 주장하고 있다.
NEXAFS and XMCD studies of single-phase Co doped ZnO thin films
Singh, Abhinav Pratap,Kumar, Ravi,Thakur, P,Brookes, N B,Chae, K H,Choi, W K IOP Pub 2009 Journal of Physics, Condensed Matter Vol.21 No.18
<P>A study of the electronic structure and magnetic properties of Co doped ZnO thin films synthesized by ion implantation followed by swift heavy ion irradiation is presented using near-edge x-ray absorption fine structure (NEXAFS) and x-ray magnetic circular dichroism (XMCD) measurements. The spectral features of NEXAFS at the Co L<SUB>3,2</SUB>-edge show entirely different features than that of metallic Co clusters and other Co oxide phases. The atomic multiplet calculations are performed to determine the valence state, symmetry and the crystal field splitting, which show that in the present system Co is in the 2+ state and substituted at the Zn site in tetrahedral symmetry with 10<I>Dq</I> = −0.6 eV. The ferromagnetic character of these materials is confirmed through XMCD spectra. To rule out the possibilities of defect induced magnetism, the results are compared with Ar annealed and Ar-ion implanted pure ZnO thin films. The presented results confirm the substitution of Co at the Zn site in the ZnO matrix, which is responsible for room temperature ferromagnetism.</P>
Thakur, P.,Kumar, R.,Cezar, J.C.,Brookes, N.B.,Sharma, A.,Arora, S.K.,Gautam, S.,Kumar, A.,Chae, K.H.,Shvets, I.V. North Holland 2011 Chemical physics letters Vol.501 No.4
We report on the element-specific magnetic characterization of Ni nanoparticles (NPs) embedded in Al<SUB>2</SUB>O<SUB>3</SUB> (001) matrix prepared by ion-implantation (Ni:5x10<SUP>16</SUP>-2x10<SUP>17</SUP>ionscm<SUP>-2</SUP>) technique. The X-ray diffraction studies reveal the coexistence of fcc Ni NPs of average size ~8-19nm along with the other NiO<SUB>x</SUB> phases. X-ray magnetic circular dichroism (XMCD) experiments demonstrate the competing nature of magnetic interactions between the Ni NPs and NiO<SUB>x</SUB> phases. The ferromagnetism at 10K (for all the Ni implants) is related to the combined contribution of both phases, while the room temperature superparamagnetism at higher fluence is dominated by Ni NPs phase as confirmed by Ni L<SUB>3,2</SUB> XMCD measurements.
Orbital anisotropy in SnO<sub>2</sub> thin films and its modification by swift heavy ion irradiation
Thakur, H.,Kumar, R.,Thakur, P.,Brookes, N.B.,Sharma, K.K.,Singh, A.P.,Kumar, Y.,Gautam, S.,Chae, K.H. North Holland ; Elsevier Science Ltd 2011 Chemical physics letters Vol.511 No.4
We report on the observation of a strong orbital anisotropy in the orthorhombic phase of SnO<SUB>2</SUB> thin films and its modification by swift heavy ion (SHI) irradiation. Structural investigations along with the Raman spectroscopy show a significant distortion of the SnO<SUB>6</SUB> octahedra after SHI irradiation. The X-ray absorption and X-ray linear dichroism (XLD) experiments provide the direct evidences of change in orbital anisotropy/electronic structure due to orbital reconstruction in the SnO<SUB>2</SUB> lattice after irradiation. The XLD measurements at the O K edge confirm the deterioration in the SnO<SUB>6</SUB> octahedra due to controlled structural disorder induced by SHI irradiation.