• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.4
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• pp.270-274
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• 2006

This study proposes a new method for automatic recording of snowfall by a mass unit which is required in weather forecast and hydrology research. In this method the weight of a buoyancy bar submerged in a liquid is measured by a strain-gauge loadcell. Field test results of the strain-gauge loadcell showed good stability as well as high accuracy. Indoor tests of the instrument using a large tank of 120 cm diameter and 25 cm height connected to a small tank measured the liquid level with a good stability, showing a measurement error of less than 0.1 mm in a 100 mm range. This method of water depth measurement is very useful in measuring snowfall because it has no limitation on the funnel size of the instrument. In addition, an antifreezing solution instead of water used in the tank makes a heating system for melting snow unnecessary.

• Korean Journal of Materials Research
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• v.12 no.8
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• pp.641-649
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• 2002

The redox properties of a homogeneously-precipitated $TiO_2$ rutile powder with a BET surface area of ~$200 m^2$/g, consisting of an acicular primary particle, were characterized using photocatalytic reaction in aqueous 4-chlorophenol, Cu-EDTA and Pb-EDTA solutions under ultraviolet irradiation, compared to those of commercial P-25 X$200 m_2$ powder with a spherical primary particle as well as home-made anatase $TiO_2$ powder with ~$200 m^2$/g BET surface area. Here, the anatase powder also includes mainly the primary particles very similar to the acicular shapes of the rutile $TiO_2$ powder. The rutile powder showed the fastest decomposition rate and the largest amount in the photoredor, compared with the anatase or P-25 powder, while the anatase powder unexpectedly showed the slowest rate and the smallest amount in the same experiments regardless of almost the same surface area. From results, the excellent photoredox abilities of this rutile powder appears to be due to specific powder preparation method, like a homogeneous precipitation leading to direct crystallization from the solution, regardless of their crystalline structures even when having the similar particle shape and surface area.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.2 no.1
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• pp.51-59
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• 1992

Effect of agglomeration of $Nb_20_5$ of the same primary particle size on formation reaction and sintering of $Pb(Mg_{1/3}\;Nb_{2/3})O_3$ was examined. Both solid state reaction and molten salt synthesis were adopted. With decreasing agglomeration of $Nb_20_5$ increased the rate of formation reaction of perovskite PMN in solid state reaction, but had little influence in molten salt synthesis. It was concluded that the increase in the inhomogeneity of the dispersion state of intermediate pyrochlore with increasing agglomeration of $Nb_20_5$ retarded the formation reaction of perovskite PMN in solid state reaction, while had little influnce in molten salt synthesis due to its solution - precipitation mechanism -mainly depends on powder surface area.

• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.46-52
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• 1992

$TiO_2/SO_4{^{2-}}$ was prepared by precipitation from the mixed solution of titanium chloride and hydrochloric acid followed by modification with sulfuric acid. The characterization of prepared catalyst was performed by using IR, XPS, XRD and DT-TGA. Infrared spectra of $TiO_2/SO_4{^{2-}}$ showed bidentate sulfate ion coordinated to the surface of $TiO_2$. The acid strength of modified catalyst was at least $H_0{\leq}-14.52$, showing the superacidic properties which are attributed to the double bond nature of S=O of the complex formed by the interaction of $TiO_2$ with sulfate ion. For $TiO_2/SO_4{^{2-}}$, the specific surface area increased and the transition from the amorphous to anatase phase occurred at a higher temperature, as compared with pure $TiO_2$.

• Journal of the Korean Ceramic Society
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• v.41 no.3
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• pp.259-265
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• 2004

The microstructure of nano-sized hydroxyapatite (HAp) powders coating layer on ZrO$_2$ substrate was investigated, which was formed by plasma spray process. The nano-sized HAp powders were successfully synthesized by precipitation of Ca(NO$_3$)$_2$$.$4H$_2$O and (NH$_4$)$_2$HPO$_4$ solution. The HAp coating layer with thickness of 150∼250 $\mu\textrm{m}$ was free from the cracks at interfaces between the coating and ZrO$_2$ substrate. In the plasma sprayed HAp coating layer, the undesirable phases were not found, while in the HAp coating layer heat-treated at 800$^{\circ}C$, TTCP, and ${\beta}$-TCP phase were detected as well as HAp phase. However, at 900$^{\circ}C$, they were completely disappeared. At 1100$^{\circ}C$, XRD analysis revealed that the coating layer was composed of the highly crystallized HAp.

• Korean Chemical Engineering Research
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• v.44 no.2
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• pp.114-120
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• 2006

Bismuth vanadate is one of the environmentally benign substitutes for conventional inorganic pigments composed of heavy metals. The effect of process parameters on the physical properties of bismuth vanadate pigment prepared from aqueous solutions of potassium vanadate and bismuth nitrate were experimentally examined. Two aqueous solutions were fed into precipitation chamber at the same flow rate, and precipitates were formed at primary pH of 4.5 and secondary pH of 7.0~7.5. After aging for 3 hours in reaction mixture, 3 hours' calcination at $400^{\circ}C$ gave bismuth vanadate pigment with a good color and hiding power. Increase in molybdenum concentration in reaction mixture increased the hiding power of the pigment, but the other minor constituents had minor effect on the physical properties of the pigment.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.5 no.2
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• pp.9-16
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• 1999

Edible films were prepared from proteins extracted from soybean curd residue by alkaline extraction and isoelectric precipitation. Effects of film forming solution pH and plasticizers on mechanical and barrier properties of edible films were studied. films were formed within pH $7{\sim}11$ with tensile strength (TS) of $2.9{\sim}3.3$ MPa. Films produced under pH 10 had the highest TS and Elongation (E) (3.3 MPa and 60.1%) but no significant difference was observed among water vapor permeabilities (WVP) of film. Glycerol, sorbitol and its mixture (1:1, w/w) were added as plasticizers. The concentration and mixing ratio of plasticizers also affected the TS, E and WVP of films. TS of films decreased from 15.0 MPa to 2.9 MPa as plasticizer concentration increased from 0.4 to 0.8 g plasticizer/g protein. At a plasticizer concentration, the highest TS was observed when sorbitol was used whereas the highest E was measured when mixture of glycerol and sorbitol was used as plasticizer WVP of films increased as the plasticizer concentration increased. Films plasticized with glycerol showed the highest WVP among the films with the same plasticizer concentrations. Edible films prepared from soybean curd residue protein showed very low oxygen permeabilities ($29.5{\sim}61.1aL{\cdot}m/m^2{\cdot}s{\cdot}Pa$) and oil resistance at all plasticizer concentration level tested.

• Resources Recycling
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• v.19 no.6
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• pp.51-60
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• 2010

A study on the recovery of cobalt and lithium from Lithium Ion Battery(LIB) scraps has been carried out by a physical treatment - leaching - solvent extraction process. The cathode scraps of LIB in production were used as a material of this experiment. The best condition for recovering cobalt from the anode scraps was acquired in each process. The cathode scraps are dissolved in 2M sulfuric acid solution with hydrogen peroxide at $95^{\circ}C$, 700 rpm. The cobalt is concentrated from the leaching solution by means of a solvent extraction circuit with bis(2-ethylhexyl) phosphoric acid(D2EHPA) and PC88A in kerosene, and then cobalt and lithium are recovered as cobalt hydroxide and lithium carbonate by precipitation technology. The purity of cobalt oxide powder was over 99.98% and the average particle size after milling was about 10 lim. The over all recoveries are over 95% for cobalt and lithium. The pilot test of mechanical separation was carried out for the recovery of cobalt from the scraps. The $Co_3O_4$ powder was made by the heat treatment of $Co(OH)_2$ and the average particle size was about 10 ${\mu}m$ after grinding. The recovery was over 99% for cobalt and lithium each other and the purity of cobalt oxide was over 99.98%.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.3
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• pp.223-229
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• 1986

These studies were investigated ionic balance of leaves from different stalk positions of tobacco plant (cv. NC82) grown on pots supplied with nitrate salts solution in the phytotrone. The results of studies are summerized as follows: 1. In comparision with the leaves along the stalk positions, lower position contained higher proportion of total cation and total anion including organic acid, but their concentration lessened gradually at the upper stalk. The ratio in amounts of inorganic cations and anions in leaf laminae depended on their stalk positon, being more than three times in the fifth, but becoming about 1.3 in the tenth. 2. Inorganic cations in the laminae were mostly $K^+$, $Ca^{{+}{+}}$, and $Mg^{{+}{+}}$, comprising about 80% of total with the first two regardless of their stalk positions. Among these two ions $Ca^{{+}{+}}$ tended to become higher at lower stalks, while $K^+$ was higher in younger and became lower when leaves got older and/or more number of leaves were emerged. 3. Total cations were balanced with inorganic and organic acid anions. Composition of inorganic and organic anions were different along stalk positions, ionic balance was governed by organic acid anions dominantly in older leaves, but by inorganic anions in the younger leaves. 4. The discrepancy in the balance between total cations and anions was more pronounced in the older leaves containing higher amount of cations and organic acids. It was suggested that discrepancy was due to precipitation of oxalate as Ca-salt which was not dissolved in the methylation solution of measurement employed.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.1
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• pp.113-116
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• 2011

Purpose: Acetylcholine receptor antibodies cause acetylcholine receptor loss, which is responsible for failure of the neuromuscular junction in the acetylcholine receptor autoantibody. The disease characterized by muscle weakness and fatigue, myasthenia gravis(MG) occurs when the body inappropriately produces antibodies against acetylcholine receptors, and thus inhibits proper acetylcholine signal transmission. And this reason, the measurement of acetylcholine receptor antibodies can be of considerable value in disease diagnosis. Methods: From 2010. August to September, we tested orderd AchRAb 19 samples to get the results. 1. Pipette $5{\mu}{\ell}$ undiluted patient sera and kit control and add 125I AChR $50{\mu}{\ell}$ and incubate at R.T for 2 hours. 2. Pipette $50{\mu}{\ell}$ of anti-human IgG into each tube, and incubate at $2{\sim}8^{\circ}C$ for 2 hours. 3. Pipette $25{\mu}{\ell}$ precipitation enhancer into each tube and add 1mL washing solution into all tubes. 4. Centrifuge each tube for 20minutes at $2{\sim}8^{\circ}C$ at 1500g. 5. Aspirate or decant the supernatant. 6. Pipette 1 mL washing solution into all tubes and resuspend the pellet and repeat centrifugation. 7. Aspirate or decant the supernatant and count all tubes on a gamma counter. Results: Cut off value is 0.2 nmol/L and the results taken below 0.2 nmol/L are negative, the results above that identified as being positive values. We assayed the 19 patients samples and got 7 positive results. Of which, 6 patients were diagnosed as MG.(85.7%). Conclusions: Acetylcholine Receptor autoantibody test is intended for use by persons only for the quantitative determination of it in human serum. Even if measurement of the antibodies is not a routine test, it can be of considerable value in disease diagnosis.