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.

n-GaAs 구조에서의 ArF excimer laser annealing에 따른 Photoreflectance 특성 연구

김기홍,유재인,심준형,배인호,임진환,김진희,유재용,Kim, Ki-Hong,Yu, Jae-In,Sim, Jun-Hyoung,Bae, In-Ho,Lim, Jin-Hwan,Kim, Jin-Hi,Yu, Jae-Yong 한국진공학회 2007 Applied Science and Convergence Technology Vol.16 No.2

n-GaAs의 시료를 furnace annealing 처리와 laser annealing 처리를 한 후, PR 방법으로 비교 조사하였다. 시료는 Furnace annealing을 5 분간 $400{\sim}800^{\circ}C$에서 처리한 시료와 ArF excimer laser($30{\sim}50\;W$)로 5 분간 Laser annealing 처리 한 시료로 준비하였다. Furnace로 annealing을 한 경우에 주 신호(정점)는 1.43 eV에서 관측되었는데 비해 laser로 annealing 한 샘플은 1.42 eV로 0.01 eV가 더 작게 관측되었다. 이는 laser annealing이 furnace annealing 보다 표면과 내면에서 일어나는 열처리 효과가 더 고르게 일어나가 때문이다. We investigated variation of the photoreflectance(PR) signals for n-GaAs furnace and laser annealed. The samples were annealed by using ArF excimer laser(5 min, $30{\sim}50\;W$) and furnace(5 min $400{\sim}700^{\circ}C$). The PR signals(top point) measured from the ArF excimer laser annealed sample showed 1.42 eV and furnace annealed sample showed 1.43 eV. This result is ArF excimer laser annealed sample was uniform annealed surface and inter state.

혼성작업장을 고려한 혼합모델 조립라인의 투입순서 결정

심재홍,남상진,김정자 동아대학교 공과대학부설 생산기술연구소 1998 生産技術硏究所硏究論文集 Vol.3 No.1

Workstation of actual mixed assembly line hybrid-workstation that have open and close type workstation. Thus proposed of this research is to determine the sequencing of model that minimize line length for actual(hybrid-workstation) mixed model assembly line. We developed three mathematical formulation of the problem to minimize the overall length of a line with hybrid station. Mathematical formulation classify model by operator schedule.

골뱅이(Buccinum Undatum) 알레르기 : 감작률과 다른 음식물 항원과의 연관성 Sensitization rate and its relationship with other food allergens

이재영,윤성호,서유진,최정희,서창희,남동호,김윤근,민경업,박해심 대한천식 및 알레르기학회 2004 천식 및 알레르기 Vol.24 No.1

Background : The common whelk (Buccinum undatum) is one of the largest and most common snails in the North Atlantic. In Korea and Japan, common whelk is a popular eatable shellfish. Although shellfish has been known as the one of the most common causes of food allergy, there has been no published report on allergenecity and clinical significance of this sea snail. In this study, we determined the sensitization rate to common whelk and its relationship with other food allergens in allergy patients. Method : We carried out the skin prick test (SPT) with commonly consumed food stuffs in Korea including common whelk in 1700 patients over 1 year. The specific IgE to common whelk were detected by enzyme-linked immunosorbent assay (ELISA). ELISA inhibition test using sensitized sera was conducted. Results : SPT to common whelk was positive (≥2+) in 83 (4.9%) patients studied. Twenty-four (38.7%) of 62 SPT-positive patients had high serum specific IgE to common whelk. ELISA inhibition test showed significant inhibitions by abalone as well as by common whelk and, minimal inhibition were noted by shrimp. Significant correlation was also noted in specific IgE levels between common whelk and abalone (r=0.58, F<.05). Conclusion : IgE-sensitization rate to common whelk was 4.9% in allergy patients. Further stuides are needed to evaluate the clinical significance of sensitized patients to common whelk, and to confirm a cross reactivity with abalone. (J Asthma Allergy Immunol 24 : 77-84, 2004)

오스템퍼링한 구상흑연주철(ADI)의 드릴 가공시 경도 및 현미경조직변화에 관한 연구

조규재,장우양,심재기,홍성오,김선진 한국공작기계학회 1999 한국생산제조학회지 Vol.8 No.1

This paper was carried out to know the influence of advanced austempered ductile cast iron (ADI) on the tool life and mechanical properties of drilling machinability. For manufactured method of ADI, the spheroidal graphite cast iron were austenized at 900℃ for 1 hour and then austempered for 2 hour at 370℃ in the salt bath. And interrelationship has been investigated between tool life and mechanical characteristics of specimen material on drilling condition when the ordinary and step-feed drilling are carried out to drill holes of specimens. Tensile strength and hardness of ADI decrease and elongation of ADI increases with the increase austempered temperature. It is known that about 2 times of tool life in the case of step-feed decreases compared with ordinary feed due to the high hardness of ADI and hardness ascribed to the fact that retained austenite beame to martensite state due to cutting heat in drilling. Under the constant feed rate 0.1㎜/rev relation between hardness and length of end tip after drilling can be formularized to Hv=788.46L^-0.096 for the cutting speed 6.1m/min.

전통건축의 기후 적응성을 통한 전원주택 계획에 관한 연구

金鎭源,沈載京 三陟大學校 1998 論文集 Vol.31 No.2

This study suggests the considerations about planning of rural housing by the integrity of nature environment, and design of rural housing floor plan by understanding the characteristics of korean traditional houses with adaptation in korean climate environment.

Tripledecker 착물, (CpCo)_2(C_4R_4)과 Alkyne과의 반응

嚴在國,李元植,金碩峯,車震淳,李炯秀,李東鎬,金洪碩,沈相喆 대구효성가톨릭대학교 자연과학연구소 1993 基礎科學硏究論集 Vol.1993 No.1

트리플데카 착물류, bis-(η^5-cyclopentadienyl)-μ-(η^4-1,2,3,4-tetraalkylcyclobutadiene)dicobalt들은 Jonas시약과 2-hexyne 또는 3-hexyne을 실온에서 동량으로 반응시킬때, 50% 이상의 최대 수율이 얻어졌다. 한 종류의 트리플데카 착물인 bis-(η^5-cyclopentadienyl)-μ-(η^4-1,2,3,4-tetraalkylcyclobutadiene)dicobalt(13)는 실온에서 3-hexyne과 반응시키면, 착물 (η^5-cyclopentadienyl)cobalt-acyclopentadiene-μ-(η^4-2,4-cobaltacyclope-ntadiene)(η^5-cyclopentadienyl)cobalt(15)로 이성화되었다. 다른 한 종류의 트리플데카 착물, bis-(η^5-cyclopentadienyl)-μ-(η^4-1,3-dimethyl-2,4-dipropyl-cyclobutadiene)dicobalt(14)를 2-hexyne 과 반응시켰더니 1,3,5-tri-methyl-2,4,6-tripropyl benzene화합물이 생성되었다. The tripledecker complexes, bis-(η^5-cyclopentadienyl)-μ-(η^4-1,2,3,4-tetraalkylcyclobutadiene)dicobalt were produced by the reaction of Jonas reagent with 2-hexyne and 3-hexyne in the maxi-mum yield(above 50%) when they were reacted in eq-molar amounts at room temperature. A tripledecker complexes,bis-(η^2-cyclopentadienyl)-μ-(η^4-1,2,3,4-tetraalkylcyclobutadiene)dicobalt(13) was isomerized to (η^5-cyclopentadienyl)cobalt-acyclopentadiene-μ-(η^4-2,4-cobaltacyclope-ntadiene)(η^5-cyclopentadienyl)cobalt(15) on reacting with 3-hexyne at room temperature. Another tripledecker complex, bis-(η^5-cyclopentadienyl)-μ-(η^4-1,3-dimethyl-2,4-dipropyl-cyclobutadiene)dicobalt(14) was decomposed to give 1,3,5-trimethyl-2,4,6-trip-ropylbenzene through an intermediate complex by the reaction of 2-hexyne.

3차원 레이저 진동 측정기를 이용한 초고속 진공청소기 모터의 진동특성분석

김재열,김우진,심재기,김영석 한국공작기계학회 2004 한국공작기계학회 추계학술대회논문집 Vol.2004 No.-

Recently technology resulted in highly efficient and multiple-functional electric appliances considering environmental problems. One of the environmental problems is noise of a product in respect to its function. A vacuum cleaner is an essential electric appliance in our daily lives. However, severe noise resulted from high motor speed for improving the function of the appliance is a nuisance for the user. This noise is caused by vibration from various parts of the appliance and fluid noise during a series of intake and exhaust processes while rotating the impeller connected to the axle at a high speed of the fan motor inside the vacuum cleaner rotating around 30,000-35,000 rpm. Despite the fact that many researchers conducted studies on reducing the noise level of the fan motor in a vacuum cleaner, only few studies have been conducted considering both the theoretical and experimental aspects using fluid analysis by measuring vibration and noise. Moreover, there has not been a study that accurately compared major noise data obtained considering both of the aspects. In this study, both aspects were considered by considering the following experimental and theoretical methods to verify the major causes of noise from the fan motor in a vacuum cleaner.

모멘트법을 이용한 평판 도체의 전하분포와 용량산출

이원규,심재명,김상진 大田産業大學校 1997 한밭대학교 논문집 Vol.14 No.1

There were a few works on computation of capacitance in electrostatic problems using method of moments. Point matching method was introduced at first, which calculate charge distributions on planar conflicting surface divided into small rectangles. This method could be applied to limited geometry. For this, it was presented that a method dividing conductor surface into triangular area can be applied in plate objects. Point matching method was also used. In this paper charge distributions and capacitance are computed with rectangular and triangular area functions, and accuracy is investigated. Point matching and Galerkin's method are used for testing. When integrating, approximate and numerical method were carried out and the convergence was observed. Pulse function and impulse or pulse function for testing. When field and source points coincide, the integration was done analytically, by doing this sample results were obtained and generalized for numerical integrations. For example in applications, the convergence of solution was investigated for rectangular plate and capacitance was compared with that of circular disk which has exact value.

가스터빈 블레이드 온도 특성 및 코팅층 건전성 평가를 위한 적외선 열화상 카메라 기법 활용

김재열,심재기,최승현,최진호 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-

Key part of main equipment in a gas turbine may be likely to be damaged due to operation under high temperature, high pressure, high-speed rotation, etc. Accordingly, the cost for maintenance increases and the damaged parts may cause generation to stop. The number of parts for maintenance also increases, but diagnostics technology for the maintenance actually does not catch up with the demand. Blades are made of precipitation hardening Ni superalloy IN738 and the like for keeping hot strength. The surface of a blade is thermal-sprayed, using powder with main compositions such as Ni, Cr, Al, etc. in order to inhibit hot oxidation. Conventional regular maintenance of the coating layer of a blade is made by FPI(Fluorescent Penetrant Inspection) and MTP(Magnetic Particle Testing). Such methods, however, are complicated and take long time and also require much cost. In this study, defect diagnostics were tested for the coating layer of an industrial gas turbine blade, using an infraredthermography camera. Since the infrared thermography method can check a temperature distribution on a wide range of area by means of non-contact, it can advantageously save expenses and time as compared to conventional test methods. For the infrared thermography method, however, thermo-load must be applied onto a tested specimen and it is difficult to quantify the measured data. To solve the problems, this essay includes description about producing a specimen of a gas turbine blade (bucket), applying thermo-load onto the produced specimen, photographing thermography images by an infrared thermography camera, analyzing the thermography images, and pre-testing for analyzing defects on the coating layer of the gas turbine blade.