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Consideration of Diluents Selection and Input Amounts of the Hunter Process for Tantalum Production
Jae‑Jin Sim,Sang‑Hoon Choi,Yong‑Kwan Lee,Sung Gue Heo,Taek‑Soo Kim,Seok‑Jun Seo,Kyoung‑Tae Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7
Tantalum (Ta) is a heavy refractory metal with an atomic weight of 180.95 g/mol, a density of 16.6 g/cm3, and a high meltingpoint of 3017 °C. With its refractory characteristics, it shows excellent chemical and physical stability as well as corrosionand heat resistance at elevated temperatures. The demand for Ta metal and related compounds is increasing with the expansionof the electronics and chemical industries. The Hunter process was proven to be effective in producing Ta powder in1953. Hunter proposed a method in which potassium heptafluorotantalate (K2TaF7) was reduced by sodium (Na). Thus far,this process has been the primary commercial method to produce Ta powder. In this study, quantitative differences wereanalyzed for diluent selection. Additionally, consideration was given to changes in the caloric value depending on the inputamount of diluents. Finally, the optimum material input and the properties of the prepared Ta were analyzed. Stoichiometricratios of K2TaF7(1 mol), NaCl (6.2–6.7 mol), Na (5–7 mol) were weighed, to perform a metallothermic reduction reaction. After the reaction, the tantalum powder was recovered and the flush process was carried out. After that, it was dried in avacuum atmosphere. Physical properties such as oxygen concentration, PSA, ICP-OES, and XRD of powder were conductedto evaluate the characteristics of Ta powder that was finally manufactured.
西海岸地域 水産業發展을 위한 公開講座프로그램의 開發에 관한 硏究
金秀寬,金在璇,李禹昌,房基俊 군산대학교 1991 群山水産專門大學 硏究報告 Vol.25 No.1
The purpose of this study is to develop the extension program for the improvement of fisheries industry in the western coastal area by making the workers in fisheries understand its environment and obtain the knowledge and the skill about it. To attain the above purpose, theoretical and empirical approaches are used in this study. The extention program developed by this study will be a useful source material to the institutes which plan social education for the workers in fisheries. Suggestions for the activation and settlement of the social education are as follows. First, the frequency of the social education about fisheries will have to be increased. Second, the main institutes of social education will have to be diversed to specialize the education line and method. Third, the required subjects in pratical field will have to be selected and educated for improving the effect of social education.
Response Matrix 에 의한 감마線 Spectrum 및 그 照射線量 解析
金成冠,田載植 대한방사선 방어학회 1986 방사선방어학회지 Vol.11 No.1
3'×3' 원통형 NaI(T1) 검출기와 多重波高分錫器를 사용하여 측정한 0.05~2.0MeV 구간의 γ선 spectrum에서 實spectrum을 구하기 위하여 照射線量率산출에 편리한 response matrix방법을 사용하였다. Response matrix구성에는, 위의 에너지 구간을 0.1MeV의 등간격으로 나눈 20×20 matrix로 한것과 검출기의 분해능이 입사 γ선 에너지의 平方根에 의존한다는 가정하에 0.1(MeV)?구간으로 나누어 14×14matrix로 구성한, 두가지 방법을 사용하였으며 그 逆matrix들은 P-E82/32콤퓨터로 계산하였다. 이 방법으로 얻은 조사선량율은 에너지와 flux가 알려진 γ선場에 대하여 흔히 사용되는 계산방법으로 구한값과 10% 이내에서 일치하고 있으며, 線量測定學的 견지에서는 E? 구간으로 형성된 matrix가 등에너지간격으로 구성된 것보다 현실적인 것으로 판단되었다. A study has been carried out for figuring out real photon spectrum from an observed gamma-ray spectrum by means of response matrix method, which is known ofe of the relatively convenient method for the estimation of exposure rate of a complex gamma ray field in comparison with graphical analysis and least square fitting of the measured spectrum. A 3"×3" cylindrical Nal(T1) scintillation detector in association with multichannel pulse height analyzer and six reference gamma ray sources covering the photon energy range of 0.05 to 2.0 MeV were used. In dividing the energy region for the construction of response matrix, two different approaches were attempted. One is dividing the entire energy region of interest into 20 bins, one of which corresponds to a width of 0.1 MeV to form 20×20 matrix, and another is dividing the 2MeV region into 14 bins to form 14×14 matrix consists of 0.1(MeV)? Intervals assuming the resolution of the detector is dependent on square root of the incident photon energy. Inversion of thus constructed matrices was performed by a computer(P-E8/32) using the program attached to the end of this paper. The resultant exposure rates obtained by this method were in good agreement, within 10% with those calculated by ordinary formula widely used for a gamma-ray field of known energy and flux. It is concluded that the photen flux obtained by the response matrix constructed under the assumption of E? dependence is more realistic than that obtained by the matrix consist of identical energy bins in dosimetrical point of view.
電算化 斷層撮影像에 關한 畵像 再構成法의 數理學的 考察
南尙熙,宋在寬,趙準錫 대구보건대학 1981 대구보건대학 論文集 Vol.5 No.-
The basic principle behind computed tomography is that the internal structure of an object can be reconstructed from multiple projections of the object. The mathematical methods is to produce an accruate cross-sectional display of the linear attenuation coeffidients of each element in the image matrix. This mathematical methods of image reconstruction are described : 1. Back-projection (Sumation method) 2. Iterative methods(Algebraic reconstruction tehnique) 3. Analytical methods (Fourier transformation) We will only attempt a pictorial explanation of the two popular analytic methods, which are two - dimensional fourier analysis and filtered back projection. The basic of fourier analysis is that any function of time or space can be represented by the sum of various projection data. This type of mathematical manipulation is easily and quickly processed in a computer. The reconstruction is a little more complex for a two-dimensional image such as a CT, but the basic principle is the same.