• YAKHAK HOEJI
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• v.4 no.1
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• pp.43-46
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• 1959

A new quantitiative analytical method of prussic acid by "Microdiffusion analysis" was studied. HCN-Glucoside of ARMENIACA was hydrolysed with KOH in out-room of unit, and then concentrated sulfuric acid was poured in order to liberate the HCN gas. The liberated gas was absorbed into nickel sulfate solution of inner room of unit quantitatively. The excess of nickel sulfate was determined by EDTA Reagent using MX-indicator. By this method, the following results were obtained: (1) It was needed more than 4 hours, in order to hydrolyse completely at $50^{\circ}C$, but could be shortened to 3 hrs. at $^60{\circ}C$. (2) It was completely absorbed into nickel sulfate solution after 30min.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.585-588
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• 2005

The dissolution characteristic of metal shows the different tendency according to the applied electrical potential, the kind of electrolyte and pH value, etc. In the micro electrochemical machining (ECM), unfavorable oxide/passive layer formation and overall corrosion of electrodes must be prevented. The anodic polarization curve of nickel has distinct three dissolution regions, i.e. two active regions and the transpassive dissolution region. In this paper, the stable electrode potentials of workpiece and tool were determined in sulfuric acid and hydrochloric acid solution, respectively. In each solution, different machining property was shown and possible electrochemical reactions were discussed. On the basis of this experiment, the methodology to obtain the proper electrode potential was suggested.

• Bulletin of the Korean Chemical Society
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• v.12 no.4
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• pp.368-370
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• 1991

The electrochemical behavior and the complex formation between N$i^{2+}$ and 1,7-diazs-15-crown-5 and 1,10-diaza-18-crown-6 in acetonitrile solution have been studied by DC polarography, differential puke polarography and cyclic voltammetry. Nickel(Ⅱ) complexes gave a single well-defined wave. The formation constants of their complexes were 1$0^{4.89} and 10^{3.86}$, respectively. Nickel(Ⅱ) ion was found to form complexes of 1-to-1 composition with 1,7-diaza-15-crown-5 and 1,10-diaza-18-crown-6. In addition, reduction steps were irreversible and the reduction current were diffusion controlled. The electrochemical reduction mechanism of Ni(Ⅱ)-macrocyclic diaza-crown complexes in acetonitrile solution is estimated.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.758-767
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• 1995

The purpose of this study was to evaluate canal shaping ability after canal preparation by using engine-driven nickel-titanium file and endosonic file in curved canals. 30 mesiobuccal canals of molars extracted within recent 3 months were divided into 3 groups. Group I and group II were prepared by using engine-driven nickel-titanium Gates-Glidden drill type and the engine-driven nickel-titanium file type. Group III prepared by using en do sonic file. The image of preinstrumented canals was taken by X-ray. The image of postinstrumented canal was taken by X-ray in the same condition of preinstrumentation. A magnified X-ray image on magnifier screen was traced and then compared the preinstrumentated canal image with the postinstrumentated canal image by superimposing method. The following results were obtained : 1. In the change of canal curvature, the engine-driven nickel-titanium Gates-Glidden drill type showed the least change and the ultrasonically filing showed the greatest change. 2. In the percentage of canal enlargement, the engine-driven nickel-titanium file type was greatest at all level(p<0.05), the apex of all group was the greatest, the difference of ultrasonically filing group showed greater between apex and cervix. 3. The percentage of canal enlargement on convex side was greater than that of on concave side in apex of each group(p<0.05). In the ultrasonically filing group, both sides of canal enlargement showed sharply difference(p<0.01). 4. The percentage of canal enlargement on convex side was greater than that of on concave side in the third of cervix of the engine-driven nickel-titanium file type and the ultrasonically filling. The percentage of canal enlargement of convex and concave side in the third of middle of the engine-driven nickel-titanium Gates-Glidden drill type show a similar canal enlargement between convex side and concave side. As above result, the engine-driven nickel-titanium file type was greater in canal enlargement than the other instruments. The engine-driven nickel-titanium Gates-Glidden dirll type was efficient endodontic instrument for curved canal preparation because it was least change in canal curvature.

• Journal of Electrochemical Science and Technology
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• v.8 no.3
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• pp.236-243
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• 2017

A fixed-bed zinc/nickel redox flow battery (RFB) is designed and developed. The proposed cell has been established in the form of a fixed bed RFB. The zinc electrode is immersed in an aqueous NaOH solution (anolyte solution) and the nickel electrode is immersed in the catholyte solution which is a mixture of potassium ferrocyanide, potassium ferricyanide and sodium hydroxide as the supporting electrolyte. In the present work, the electrode area has been maximized to $1500cm^2$ to enforce an increase in the energy efficiency up to 77.02% at a current density $0.06mA/cm^2$ using a flow rate $35cm^3/s$, a concentration of the anolyte solution is $1.5mol\;L^{-1}$ NaOH and the catholyte solution is $1.5mol\;L^{-1}$ NaOH as a supporting electrolyte mixed with $0.2mol\;L^{-1}$ equimolar of potassium ferrocyanide and potassium ferricyanide. The outlined results from this study are described on the basis of battery performance with respect to the current density, velocity in different electrolytes conditions, energy efficiency, voltage efficiency and power of the battery.

• Korean Journal of Crystallography
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• v.12 no.2
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• pp.88-91
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• 2001

The complex [NiL₃]Cl₂·3H₂O (1) (L=trans-1,2-diaminocyclohexane) has been synthesized and characterized by X-ray crystallography. The compound 1 crystallizes in the cubic space group P2₁3, with a=13.830(1) Å, V=2645.9(2) ų, Z=4, R₁(wR₂) for 1500 observed reflections of [I> 2σ(I)] was 0.0766 (0.2068).

• Journal of the Korean institute of surface engineering
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• v.38 no.1
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• pp.21-27
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• 2005

Tensile properties and hardness of nickel electroform from chloride-free nickel sulfamate electrolyte at 50℃ and PH 4.5 were investigated. Current density varied from 20 to 60 mA/㎠. The deposit thicknesses were 360, 480 and 980 ㎛. It was found in 480 ㎛ thick electroform that highest tensile and yield strengths and hardness of 83.7 ksi, 53.6 ksi and 216 DPH, respectively were obtained at a current density of 40 mA/㎠ and they were slightly decreased at 20 and 60 mA/㎠. However the ductility was lowest of 7.9% at 40 mA/㎠. Such a high strength and low ductility at 40 mA/㎠ seems to be related to the narrower columnar structure than those of other current densities. All the deposits exhibited pronounced necking behavior. Tensile strength, yield strength and ductility increased as the nickel electroform thickens. Initial strong (200) texture developed on stainless steel mandrel decreased and (111) and (220) textures increased as deposit thickness increased, whereas (200) texture was preferred as the current density increased.

• Resources Recycling
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• v.7 no.1
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• pp.27-33
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• 1998

A study on thc recovcry oi nickel from waste pickling solutions removed li-ee nil~ica cid and hydmflnoric acid is carried out with pulsed column extractor for thc industrial application. The ~esults show that thc Iron and chromium arc efteclively elunmatcd from the waste solution by precipitalion as the form of hydraxidc with thc adjustment of pH with CaCO;, whlle the nickel is not prcc~pitatcd. Thc cxlraction eficicncy ol nickel with column cxtraclor generally improves 8s the pulse velosity (product of amplmde and frequency) incrcascs, optimum pcrfarmancc typically occuring slightly below an amplihldefrecluency product which results in flooding the column because of excessive emulsiIicalian And the nickel loaded in the organic is erfeclively conce~~trtratebdy ZM H2S0,, ~ I It he stlipping stage. The solubility of NiSO, in the H,SO, solution dccreaaes w~th thc higher H,SO, concentralion and appears to be 55 grL in the 2M HSO* solulian.

• Journal of the Korean Chemical Society
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• v.22 no.1
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• pp.19-24
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• 1978

Novel nickel(II) complexes of the type Ni(IBA-NH)(IBA-NR), where IBA-NH and IBA-NR (R=H, methyl, ethyl, n-propyl, iso-propyl, n-butyl or benzyl) represent isonitrosobenzoylacetone imine and its N-alkyl derivative respectively, have been prepared. The ir, nmr, and electronic spectra and magnetic moment of the nickel(II) complexes have been studied. It has been determined that the isonitroso group of IBA-NH coordinates to nickel through the oxygen to form 6-membered chelate ring and that of IBA-NR coordinates to nickel through the nitrogen to form 5-membered ring in square-planar Ni(IBA-NH) (IBA-NR). The coordination manner of the ligands is similar to that of isonitrosoacetylacetone imines obtained by Bose, et al.

• The korean journal of orthodontics
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• v.48 no.3
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• pp.153-162
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• 2018

Objective: The aim of this trial was to compare the alignment efficiency and intermaxillary arch dimension changes of nickel-titanium (NiTi) or copper-nickel-titanium (CuNiTi) round archwires with increasing diameters applied sequentially to the mandibular arch. Methods: The initial alignment phase of fixed orthodontic treatment with NiTi or CuNiTi round archwires was studied in a randomly allocated sample of 66 patients. The NiTi group comprised 26 women, 10 men, and the CuNiTi ($27^{\circ}C$) group comprised 20 women, 10 men. The eligibility criteria were as follows: anterior mandibular crowding of minimum 6 mm according to Little's Irregularity Index (LII), treatment requiring no extraction of premolars, 12 to 18 years of age, permanent dentition, skeletal and dental Class I malocclusion. The main outcome measure was the alignment of the mandibular anterior dentition; the secondary outcome measure was the change in mandibular dental arch dimensions during 12 weeks. Simple randomization (allocation ratio 1:1) was used in this single-blind study. LII and mandibular arch dimensions were measured on three-dimensional digital dental models at 2-week intervals. Results: No statistically significant difference was observed between NiTi and CuNiTi according to LII (p > 0.05). Intercanine and intermolar arch perimeters increased in the CuNiTi group (p < 0.001). Inter-first premolar width showed a statistically significant interaction in week ${\times}$ diameter ${\times}$ application (p < 0.05). Conclusions: The effects of NiTi and CuNiTi round archwires were similar in terms of their alignment efficiency. However, the intercanine and intermolar arch perimeters, and the inter-first premolar width changes differed between groups.