• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.14-20
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• 2006

During the 11 year period of 1995-2005, there was about a 40% increase in the world copper demand mainly because of the Asian economic growth. In the increase, about a half was consumed by China. Most of the China's copper demand increase has been taken place over the final 5-6 years of that period. The growth is expected to continue for several years, and in 10 years or sooner the same situation is expected for India. Copper is the third metal in global demand, but its little abundance in the Earth's crust is not well recognized. From the production rate and the abundance, a copper shortage, or crisis, has a high probability than the other metals. Deep ocean mineral resources such as manganese nodules in the Clarion-Clipperton Fracture Zones, Kuroko-type massive seafloor sulfides (SMS), and cobalt-rich manganese crusts in the EEZ and the high sea areas have big potentials for the future sources. We need to re-evaluate their potentials as copper resources and other metals to realize their developments. The same situation is under progress in the hydro-carbon markets. Methane hydrates that are classified into non-conventional hydro-carbon resources have an important role as the future sources, too.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.143-147
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• 2001

Ferromagnetism in manganese compound semiconductors open prospects for tailoring magnetic and spin-related phenomena in semiconductors with a precision specific to III-V compounds. Also it addresses a question about the origin of the magnetic interactions that lead to a Curie temperature(Tc) as high as 110 K for a manganese concentration of just 5%. Zener's model of ferromagnetism, originally suggested for transition metals in 1950, can explain Tc of $Ga_{1-x}Mn_x$ As and that of its IT-VI counterpart $Zn_{1-x}Mn_x$ Te and is used to predict materials with Tc exceeding room temperature, an important step toward semiconductor electronics that use both charge and spin. In this article, we present not only the experimental result but calculated Curie temperature by RKKY interaction. The problem in making III-V semiconductor has been the low solubility of magnetic elements, such as manganese, in the compound, since the magnetic effects are roughly proportional to the concentration of the magnetic ions. Low solubility of magnetic elements was overcome by low-temperature nonequilibrium MBE{molecular beam epitaxy) growth, and ferromagnetic (Ga,Mn)As was realized. Magnetotransport measurements revealed that the magnetic transition temperature can be as high as 110 K for a small manganese concentration.

• Journal of the Korean Society of Tobacco Science
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• v.8 no.2
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• pp.29-41
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• 1986

Effects of some mineral nutrients on the chlorine absorption by the plants, on the chemical constituents and physical properties of leaves were investigated tinder the paddy field and pot conditions. The chlorine content of cured leaf grown in paddy field was high in iron and manganese application groups and highest in combined application of iron and manganese. Lime application inhibited the absorption of chlorine and increased the yield and quality of cured leaf, and inhibited the absorption of iron and manganese those causing the grey leaf. Lime application reduced the leaf chlorine content and rate of muddy grey leaf by increasing the soil pH in acid soil.

• Journal of Environmental Science International
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• v.17 no.9
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• pp.943-947
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• 2008

For the purpose of safety identification, the concentrations of heavy metals in seaweeds collected from Busan Gijang coastal area were investigated. The average concentration of metals had a level of as high as the order of manganese (2.76 ppm)>zinc(2.11 ppm)>copper(0.59 ppm)>arsenic (0.092 ppm)>lead(0.06 ppm)> mercury(0.03 ppm)>cadmium(0.026 ppm). The contents of manganese and zinc were highly detected from P. elliptica, copper and mercury from agar, cadmium from sea mustard and arsenic from wild sea mustard, respectively. The metal contents of seaweeds varied with kinds of samples, but high level for the safety can be found in these samples. Because P. elliptica had shown a clear selectivity for both manganese and zinc, this seaweed could be useful as a bioindicator for these two metal pollution.

• Journal of Electrochemical Science and Technology
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• v.3 no.4
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• pp.178-184
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• 2012

A porous nickel (P-Ni) substrate was prepared by selective leaching of zinc from pressed pellets containing powders of Ni & Zn in 4 M NaOH solution. Anodic deposition of manganese oxide onto the porous Ni substrate ($MnO_x$/P-Ni) formed nano-flakes of manganese oxide layers as revealed in SEM studies. Pseudocapacitance of this oxide electrode was evaluated by cyclic voltammetry (CV) and chronopotentiometry (CHP) in 2 M NaOH solution. The specific capacitance of the Mn oxide electrode was as high as 1515 F $g^{-1}$, which was ten times higher than Mn oxide deposited on a flat Ni-ribbon. 80% of capacity was retained after 200 charge/discharge cycles. The system showed no loss of activity in dry form over period of days. The impedance studies indicated highly conducting $MnO_x$/P-Ni substance and the obtained specific capacitance from impedance data showed good agreement with the charge/discharge measurements.

• Journal of environmental and Sanitary engineering
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• v.4 no.1 s.6
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• pp.53-60
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• 1989

This study was performed to investigate the contents of heavy metals in Anguilla japonica habiting in Korea. The samples were collected along by Nak Tongriver, Young San river and culture farms. Lead, Cadmium, Copper, Zinc, Manganese, Chromium were tested by the Atomic Absoption Spectrop-hotometer after wet digestion, Mercury was tested by using mercury analyzer. The results were as follows: 1. Aresenic, Copper contents in the four parts were the higest values in liver 2. In total mercury contents of the each parts, the higest value was detected in muscle. 3. In all metals, Zinc and Manganese were detected with high contents, Mecury and Cadmium were detected with low contents. Lead, Cadmium, Zinc, chromiumi, Manganese were detected with high in bone. 4, The difference was not significant between natural and feeding Anguilla Japonica, but significant correlation with parts.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.2
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• pp.249-255
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• 2014

So many drinking water treatment plants are under various difficulties by new reinforced effluent standards. Since the target turbidity, much higher than annual average, for designing sludge thickener have to be set to confront high turbidity season, the sludge at thickener should be put up for a long time during usual days. So the soluble manganese and chloroform may be formed under the anaerobic environment in the sludge thickener when the sludge retention time is longer with low turbidity. This phenomenon results in difficulties to keep regulatory level of the discharged effluent. For an effort to overcome the problems, a sludge aeration was successfully implemented into the thickening process. As a result, the final effluent quality and sludge volume were much improved; 41 % of manganese, 62 % of chloroform and 35 % of sludge volume. Additionally, effluent quality was improved ; 61 % of Manganese on aeration with pH control and we could make sure of stability effluent quality despite a long sludge retention time. We recommended the standard of installation sludge aeration equipment to nationally supply water treatment plant under effluent water quality problem ; Manganese, Chloroform, etc.

• Korean Journal of Metals and Materials
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• v.47 no.5
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• pp.304-310
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• 2009

Recently, manganese nodule has been focused on alternative resources because of its high grade of noble metallic elements such as Co, Ni, and Cu etc. From the viewpoint of an optimization the operating variables for energy efficiency of smelting reduction process, thermodynamic model for smelting reduction process of Manganese nodule was developed by using energy and material balance concept. This model provided that specific consumption of pure oxygen and coke was strongly depended on post combustion ratio (PCR) and heat transfer efficiency (HTE). The dressing and dehydrating process of low grade manganese can be proposed an essential process to minimize the specific energy consumption with decreasing slag volume. The effect of electricity coal base smelting reduction process was also discussed from the energy optimizing point of view.

• Corrosion Science and Technology
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• v.13 no.3
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• pp.102-106
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• 2014

Nickel electrodeposition from sulfamate bath has several benefits such as low internal stress, high current density and good ductility. In nickel deposited layers, sulfur induces high temperature embrittlement, as Ni-S compound has a low melting temperature. To overcome high temperature embrittlement problem, adding manganese is one of the good methods. Manganese makes Mn-S compound having a high melting temperature above $1500^{\circ}C$. In this work, the mechanical properties of Ni-Mn deposited layers were investigated by using various process variables such as concentration of Mn$(NH_2SO_3)_2$, current density, and bath temperature. As the Mn content of electrodeposited layers was increased, internal stress and hardness were increased. By increasing current density, internal stress increased, but hardness decreased. With increasing the bath temperature from 55 to $70^{\circ}C$, internal stress of Ni deposit layers decreased, but hardness didn't change by bath temperature. It was likely that eutectoid manganese led to lattice deformation, and the lattice deformation increased hardness and internal stress in Ni-Mn layers. Increasing current density and decreasing bath temperature would increase a mount of $H_2$ absorption, which was a cause for the rise of internal stress.

• Journal of the Korean institute of surface engineering
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• v.53 no.1
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• pp.22-28
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• 2020

In this study, manganese dioxide (MnO₂) nanoparticles were synthesized from KMnO₄ and MnCl₂·4H₂O without any dispersing agents and oxidant via ultra-high pressure homogenization process. We investigated various physicochemical properties and CO oxidation reactions of the MnO₂ nanoparticles as a function of the number of passes at 1,500 bar in a high pressure homogenizer nozzle. The observed X-ray diffraction patterns and scanning electron microscopy images revealed that the synthesized MnO₂ nanoparticles had a hexagonal structure and a uniform spherical shape. It was found from the Brunauer-Emmett-Teller measurements that the pore size of the MnO₂ nanoparticles ranged from 23.6 to 7.2 nm and their specific surface area ranged from 24 to 208 m²g^-1. In particular, it was confirmed from the measurements of CO conversion into CO₂ that CO oxidation reaction over the MnO₂ nanoparticles exhibited excellent catalytic activity at low temperatures below 100℃.