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(Fe<SUB>0.95</SUB>Ni<SUB>0.05</SUB>)<SUB>7</SUB>Se<SUB>8</SUB>의 뫼스바우어 분광학적 연구
김응찬(Eng-Chan Kim) 한국자기학회 2014 韓國磁氣學會誌 Vol.24 No.2
By Mossbauer spectroscopy and x-ray measurement (Fe<SUB>0.95</SUB>Ni<SUB>0.05</SUB>)<SUB>7</SUB>Se<SUB>8</SUB> has been studied. The crystal structure of (Fe0.95Ni0.05)7Se8 is found to be a triclinic superstructure of the NiAs sturcture while Fe<SUB>7</SUB>Se<SUB>8</SUB> has a orthohexagonal superstructure. Abrupt changes of quadrupole shifts near 125 K for (Fe<SUB>0.95</SUB>Ni<SUB>0.05</SUB>)<SUB>7</SUB>Se<SUB>8 </SUB>suggests that the spin-rotation transition proceeds abruptly, in contrast with the gradual transition reported for Fe<SUB>7</SUB>Se<SUB>8</SUB> with a triclinic superstructure. Isomer shifts indicate a ferrous state for the iron ions at all four states.
직장암 3문조사와 자궁경부암 4문조사 방사선 치료 시 유리선량계를 이용한 피부선량 측정에 관한 연구
신성수(Seong-Soo Shin),최원식(Won-Sik Choi),박철수(Cheol-Soo Park),이선엽(Sun-Yeb Lee),조재환(Jae-Hwan Cho),서정민(Jeong-Min Seo),심재구(Jae-Koo Shim),김찬형(Chan-Hyeong Kim),구은회(Eun-Hoe Goo),김응찬(Eng-Chan Kim) 대한방사선과학회 2011 방사선기술과학 Vol.34 No.2
현재의 방사선 치료의학은 고도로 발전하여 다양한 기술의 방사선 치료기술(IMRT, SRS, 3D-RT, 등)이 행하여지고 있다. 자궁경부암의 방사선 치료나 직장암의 방사선 치료에서는 아직까지 보편화된 치료법인 3문조사법이나 4문조사법을 실시하고 있다. 2차원 치료 시 치료부위 피부에 방사선에 의한 화상이 생기게 된다. 이러한 피부 부작용은 방사선 치료의 대표적인 부작용이라 할 수 있다. 지금까지는 피부선량 측정에 있어서 1회 측정으로 총 치료기간을 환산하여 피부선량을 기술하였다. 본 연구에서는 환자의 매회 치료 시 마다 피부선량을 측정하였다. 피부선량 측정에는 누적선량 측정에 적합한 유리선량계를 사용하였다. 피부선량 측정 후 치료계획 장치에서 측정한 피부선량과 비교 분석하였다. 치료기간 동안 매번 측정한 피부선량과 치료 계획 장치에서 계산한 선량을 서로 유의성 분석을 실시한 결과 유의하다는 결과를 없었다. 환자치료 시 움직임에 의한 오차가 있음에도 치료 계획 장치의 계산 선량과 비교하여도 오차범위에 합당하였다. Recently a variety of high technologies for radiation therapy (IMRT, SRS,. 3D-RT, etc.) has been developed. For the cervical and rectal cancer, 3field or 4field radiotherapy have been applied to the patients. In the case of two-dimensional treatment, one of the most typical side-effects is skin burn due to the radiation irradiation. In general the skin dose is evaluated by only a single measurement during the whole treatment period. In this study, however, skin dose was measured in each radiation treatment and the total skin dose was accumulated in a glass dosimeter through all the cases. After simulating the skin dose from treatment planning system, the results were compared with the actual skin doses. The results showed a good agreement between two data sets. Even though there are certain amount of errors caused by the patient movement along the treatment, the difference between actual dose and simulated dose was within the accepted range of error.
김응찬 嶺南大學校基礎科學硏究所 1999 基礎科學硏究 Vol.19 No.-
We used the discrepancy method to receive the quantitive information about the distribution function of the effective magnetic field H_n in Mo¨ssbauer spectroscopy. NiFe_2O_4 was used as a model object because of a priori known information about the desired function. To demonstrate discrepancy method ability in search for the distribution function of the effective magnetic field on nuclei we used data for the experimental spectrum of ^57Fe in NiFe_2O_4 a different parameters. An outstanding peculiarity of the discrepancy method, that if one intend to receive more detailed information about the distribution function the noise level will increase at a great extent, was manifested in the obtained results.
김응찬 嶺南大學校 基礎科學硏究所 1997 基礎科學硏究 Vol.17 No.-
To determine whether there is an ionic substitution of Ni, Co, Mn, and Al for Fe in synthetic goethites these materials have been studied by Mossbauer spectroscopy at various temperatures. It is found that the presence of substituting elements in magnetically ordered structure of crystals may change the shape of Mossbauer spectra of these materials. The approximate distribution function of the effective magnetic field in the Fe nucleus p(Hn) was obtained from the Mossbauer spectra. It is noted that the mean value of p(Hn) and its integral width can be taken as a measure of substitution in goethites.
김응찬 嶺南大學校 基礎科學硏究所 1996 基礎科學硏究 Vol.16 No.-
Stability of the properties of magnetite particles in novel medicinal magnetic ointments of multipurpose application has been studied with Mossbauer spectroscopy. Comparative analysis of the results obtained by model fitting of ?? nuclei spectra with those known for the system Fe₂O₄- r - Fe₂O₃ allowed to identify the phase composition of the particles. This composition, as well as that of the initial pure component in the form of a highly dispersed fraction (~??), differs noticeably from the stoichiometric one. Despite their small sizes, the particles exhibit no superparamagnetism (in the temperature range from 95 or 300K). Radiative sterillization of the ointments has no effect on the magnetic component composition.
스피넬 구조의 자유 매개 변수와 뫼스바우어 흡수선 이동
김응찬 嶺南大學校基礎科學硏究所 1999 基礎科學硏究 Vol.19 No.-
The dependence of the Mo¨ssbauer lineshift δ in oxygen ferrite-spinels on the free parameter of the structure u is considered. The mutual disposition of the lines for the A and B points in the spectrum depends significantly on the oxygen parameter u. Within the framework of the field theory of ligands, theoretical dependences are obtained for the difference in the shifts Δδ^RA ≡ δ^B-δ^A as a function of u, at various values of the lattice parameter a. This difference is expedient for comparison with experimental data, since it does not depend on the choice of radiation source and scarcely depends on a. The available experimental data for ferrite-spinels with Fe^3+ ions at points A and B agree with the results of the calculations. In particular, the trend of the difference Δδ^BA to sign reversal with rise in u is confirmed. According to the results of the calculations, sign reversal should be observed at u= u_cr=0.3845 for the case when a=8.30A˚.
반강자성 CuFeS2-xSex의 결정학적 및 자기적 성질
김응찬 嶺南大學校 基礎科學硏究所 1997 基礎科學硏究 Vol.17 No.-
CuFeS???Se has been studied by Mossbauer spectroscopy and x-ray diffraction. The crystal is found to have a tetragonal structure and the lattice constants a? and c? increase linearly with increasing selenium concentration. It is noteworthy that the replacement of S by Se in the chalcopyrite decreases the strength of both the superexchange interaction and the interatomic binding. Isomer shift indicates a ferric character for the iron ions. The Debye temperature is found to be decreased with increasing selenium concentration.