• 한국재료학회지
• /
• 제27권12호
• /
• pp.672-678
• /
• 2017

In the production of zirconium cladding tube, a pickling acid solution is used to remove surface contaminants, which generates tons of pickling acid waste. The waste pickling solution is a valuable resource of Hf-free Zr. Many studies have investigated separating the Hf-free Zr source from the waste pickling acid. The results showed that $Ba_2ZrF_8$ precipitates prepared from the waste pickling acid were useful as an electrolyte for the electrorefining of Zr in molten salt. In the present work, electrorefining was performed in a $Ba_2ZrF_8-LiF$ binary electrolyte to recover Zr from a Hf-free CuZr ingot anode prepared by electroreduction. Before electrorefining, two pretreatments are performed. First, electrolyte melting was carried out to determine the eutectic temperature, and second, the electrolyte was treated to eliminate impurities, mainly hydride. After electrorefining, the cathode deposits were analyzed by $O_2$ gas analyzer and SEM-EDX to explore the possibility of recovering nuclear-grade Zr metal. Moreover, the anode was analyzed by SEM-EDX to determine the Zr dissolution depth.

• 한국방사선학회논문지
• /
• 제16권1호
• /
• pp.15-23
• /
• 2022

3D 프린팅 기술은 의료, 바이오 등 다양한 분야에서 활용되고 있으며, 최근 소재 개발을 통해 금속 분말이 함유된 물질 등이 상용화되고 있다. 이에 본 연구에서는 모의실험을 통해 진단 X-선 검사 시 3D 프린팅 재료를 이용한 부가 여과 시 광자 스펙트럼을 분석하고자 한다. 몬테카를로 기법 중 MCNPX(ver. 2.5.0)를 이용하였으며, 첫 번째, 진단 분야에서의 X-선 스펙트럼 생성 프로그램인 SRS-78, SpekCalc를 통해 모의실험 내 발생된 광자 스펙트럼에 대한 적정성을 평가하였다. 두 번째, 금속분말이 함유된 3D 프린팅 재료에 대한 특성 평가를 위해 기존 Al, Cu 필터와 동일한 두께 내 광자 스펙트럼을 획득하였으며, 관전압 변화에 따른 광자 플루언스 및 평균 에너지 등을 비교 분석하였다. 그 결과, 동일한 여과 정도를 나타내기 위해 PLA-Al는 기존 Al 필터 대비 약 1.2 ~ 1.4배, PLA-Cu는 Cu 필터 대비 1.4 ~ 1.7배 정도의 두께가 필요한 것으로 분석되었다. 향후 본 연구를 토대로 의료분야 내 3D 프린팅 부가 필터 제작을 위한 기초 자료로서 활용될 수 있으리라 판단된다.

• 한국의학물리학회지:의학물리
• /
• 제27권3호
• /
• pp.125-130
• /
• 2016

Dual energy computed tomography (DECT) is used to classify two materials and quantify the mass density of each material in the human body. An energy modulation filter based DECT could acquire two images, which are generated by the low- and high-energy photon spectra, in one scan, with one tube and detector. In the case of DECT using the energy modulation filter, the filter should perform the optimization process for the type of materials and thicknesses for generating two photon spectra. In this study, Geant4 Monte-Carlo simulation toolkit was used to execute the optimization process for determining the property of the energy modulation filter. In the process, various materials used for the energy modulation filter are copper (Cu, $8.96g/cm^3$), niobium (Nb, $8.57g/cm^3$), stannum (Sn, $7.31g/cm^3$), gold (Au, $19.32g/cm^3$), and lead (Pb, $11.34g/cm^3$). The thickness of the modulation filter varied from 0.1 mm to 1.0 mm. To evaluate the overlap region of the low- and high-energy spectrum, Geant4 Monte-Carlo simulation is used. The variation of the photon flux and the mean energy of photon spectrum that passes through the energy modulation filter are evaluated. In the primary photon spectrum of 80 kVp, the optimal modulation filter is a 0.1 mm lead filter that can acquire the same mean energy of 140 kVp photon spectrum. The lead filter of 0.1 mm based dual energy CBCT is required to increase the tube current 4.37 times than the original tube current owing to the 77.1% attenuation in the filter.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2003년도 추계학술대회논문집
• /
• pp.301-301
• /
• 2003

In current study, Nanocomposites are reinforced with carbon nanofiber, carbon nanotube and SiC, etc. Since the nano reinforcements have the excellent mechanical, thermal and electrical properties compared with that of existing composites, it has lately attracted considerable attention in the various areas. Cu have been widely used as signal transmission materials for electrical electronic components owing to its high electrical conductivity. However, it's size have been limited to small ones due to its poor mechanical properties. Until now, strengthening of the copper alloy was obtained either by the solid solution and precipitation hardening by adding alloy elements or the work hardening by deformation process. Adding the alloy elements lead to reduction of electrical conductivity. In this aspect, if carbon nanofiber is used as reinforcement which have outstanding mechanical strength and electric conductivity, it is possible to develope Cu matrix nanocomposite having almost no loss of electric conductivity. It is expected to be innovative in electric conducting material market. The unidirectional alignment of carbon nanofiber is the most challenging task developing the cooer matrix composites of high strength and electric conductivity. In this study, the unidirectional alignment of carbon nanofibers which is used reinforced material are controlled by drawing process and align mechanism as well as optimized drawing process parameter are verified via numerical analysis. The materials used in this study were pure copper and the nanofibers of 150nm in diameter and of 10∼20$\mu\textrm{m}$ in length. The materials have been tested and the tensile strength was 75MPa with the elongation of 44% for the copper. it is assumed that carbon nanofiber behave like porous elasto-plastic materials. Compaction test was conducted to obtain constitutive properties of carbon nanofiber Optimal parameter for drawing process was obtained by analytical and numerical analysis considering the various drawing angles, reduction areas, friction coefficient, etc. The lower drawing angles and lower reduction areas provides the less rupture of co tube is noticed during the drawing process and the better alignment of carbon nanofiber is obtained.

• Current Photovoltaic Research
• /
• 제2권3호
• /
• pp.115-119
• /
• 2014

$Cu(In,Ga)Se_2$ (CIGS) thin films have been used as a light absorbing layer in high-efficiency solar cells. In order to improve the quality of the CIGS thin film, often selenization step is applied. Especially when the thin film was formed by non-vacuum powder process, selenization can help to induce grain growth of powder and densification of the thin film. However, selenization is not trivial. It requires either the use of toxic gas, $H_2Se$, or expensive equipment which raises the overall manufacturing cost. Herein, we would like to deliver a new, simple method for selenization. In this method, instead of using a costly two-zone furnace, use of a regular tube furnace is required and selenium is supplied by a mixture of selenium and ceramic powder such as alumina. By adjusting the ratio of selenium vs. alumina powder, selenium vaporization can be carefully controlled. Under the optimized condition, steady supply of selenium vapor was possible which was evidently shown by large grain growth of CIGS within a thin powder layer.

• Transactions on Electrical and Electronic Materials
• /
• 제9권6호
• /
• pp.265-272
• /
• 2008

In this paper, AC losses of long wire Bi-2223 tapes with different twist pitch of superconducting core were fabricated, measured and analyzed. These samples produced by a powder-in-tube method are multi-filamentary tape with Ag matrix. Also, it's produced by non-twist. The critical current measurement was carried out under the environment in Liquid nitrogen and in zero field by 4-prob method. And the Magnetic measurement was carried out under the environment of applied time-varying transport current by transport method. From experiment, the susceptibility measurements were conducted while cooling in a magnetic field. Flux loss measurements were conducted as a function of ramping rate, frequency and field direction. The AC flux loss increases as the twist-pitch of the tapes decreased, in agreement with the Norris Equation. Neutron-diffraction measurements have been carried out investigate the crystal structure, magnetic structures, and magnetic phase transitions in Bi-2223([Bi, Pb]:Sr:Ca:Cu:O).

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
• /
• pp.222-224
• /
• 1997

This study is about a connective method of High Tc wire for long wire. We prepared silver-sheathed BiPbSrCaCuO wires by the powder-in-tube method. Since the superconducting wires are ceramic, it is very hard to connect each other. In this study, we used a silver sleeve to contract wires and pressed them by various preasures. Then optimum preasure was 9,000 Kgf/$\textrm{cm}^2$ to get the high critical current. The higest critical current was 10A.

• 대한전기학회논문지
• /
• 제43권6호
• /
• pp.958-964
• /
• 1994

To study on the superconducting properties with cooling conditions, silver-sheathed Bi-Pb-Sr-Ca-Cu-O wires fabricated by the powder-in-tube method. The wires cooled down in the furnace, air and liquid NS12T after sintering at 840$^{\circ}C$ Critical current density of sample cooled in the furnace is 5.1${\times}$10S03TA/cmS02T and sample cooled in the air is 40A/cmS02T at 77K, zero magnetic field. The latter is very low critical current density of Bi system. 2223 high-Tc superconducting phase of sample cooled in the air was distroyed. Properties of sample cooled down in the liquid nitrogen is the same as cooled in the furnace.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
• /
• pp.961-963
• /
• 2002

Organic electroluminesencent device have been studied because of its easy fabrication and high brightness for plate panel display instead of cathode ray tube. There are some device structure for full color filter system can be applicable to the full color application if the blue light organic electroluminesencent device(OELD) is developed. In this study, we fabricated OELD of ITO/CuPc/PBD/LiF/Al using mixed of 500, 600, $700[{\AA}]$ by vacuum method as a emitting layer. We studied the voltage-current, voltage-luminance characteristics and blue light emission of OELD,

• 한국초전도저온공학회:학술대회논문집
• /
• 한국초전도저온공학회 1999년도 제1회 학술대회논문집(KIASC 1st conference 99)
• /
• pp.10-13
• /
• 1999

For large scale applications of high temperature superconductor(HTS) such as transmission cables, motors and generators, long length of flexible HTS conductors is required. Currently, HTS tape that is capable of being fabricated in long length by industrial processes is the Bi-2223 HTS tape. In this study, we fabricated 19 filamentary Bi-2223($Bi_{1.8}$$Pb_{0.4}$$Sr_{2}$$Ca_{2}$$Cu_{3}$$O_{10+X}$) HTS tape with 100m length by PIT(Powder In Tube) process. Critical current(Ic) of this long length tape was measured 18.5 A at 77 K, self field and short sample Ic is 32.5 A at the same condition. Critical current of 100m length tape was decreased by about 1/3 compared to that of short tape. This was mainly resulted from the increase of non homogeneity in oxide layer.