• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.659-664
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• 2007

The objective of this study is to evaluate the detoxification method for the endocrine disrupting chemicals by manganese oxide. Manganese coated sand and bisphenol-A (BPA) was used as the reactive medium and the contaminant. Results showed that manganese oxide effectively degrades BPA by oxidative coupling reaction. The nonlinear oxidative coupling reaction orders were obtained for BPA and oxide, respectively. The reaction rate of BPA decreased as initial BPA concentration increased, as oxide loading decreased and as pH increased. The higher ionic strength, the higher reaction rate was observed. Divalent cations were adsorbed on the oxide surfaces, resulting in the decreased degradation rate of BPA.

• Environmental Mutagens and Carcinogens
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• v.23 no.4
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• pp.115-130
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• 2003

Idiopathic Parkinson's disease (IPD) represents a common neurodegenerative disorder. While epidemiological studies have suggested a number of risk factors including age, gender, race, and inherited disorder, the cumulative evidence supports the view that environmental or occupational exposure to certain chemicals may contribute to the initiation and progress of Parkinsonism. More recently, clinical and laboratory investigations have led to the theory that dysregulation of iron, an essential metal to body function, may underlie IPD by initiating free radical reaction, diminishing the mitochondrial energy production, and provoking the oxidative cytotoxicity. The participation of iron in neuronal cell death is especially intriguing in that iron acquisition and regulation in brain are highly conservative and thus vulnerable to interference from other metals that bear the similar chemical reactivity. Manganese neurotoxicity, induced possibly by altering iron homeostasis, is such an example. In fact, the current interest in manganese neurotoxicology stems from two primary concerns: its clinical symptoms that resemble Parkinson's disease and its increased use as an antiknock agent to replace lead in gasoline. This article will commence with addressing the current understanding of iron-associated neurodegenerative damage. The major focus will then be devoted to the mechanism whereby manganese alters iron homeostasis in brain.

• Ocean and Polar Research
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• v.25 no.3
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• pp.257-267
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• 2003

Deep-sea bottom photographs acquired in the Clarion-Clipperton fracture zone of the northeast equatorial Pacific were analyzed to reveal the controlling processes for the spatial variation of manganese nodule. The results show that regional-scale occurrence variations of manganese nodule are mainly controlled by primary productivity of surface water, sedimentation rate, and water depth (or carbonate compensation depth). As a result, the diagenetic accretion on nodules increases toward southwest while hydrogenetic accretion increases toward northeast. Considering the northwestward movement of Pacific Plate, this regional-scale variation of manganese nodule occurrence seems to be affected by oceanic environment during the active growth period (Oligocene-Miocene) of Pacific Plate.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.4
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• pp.64-72
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• 1997

백색부후균에 의한 리그닌의 분해양상을 검토하기 위해 리그닌 분해능이 우수하고 laccase활성이 높은 LKY-7 및 C. versicolor-13 균주와 manganese peroxidase 활성은 비교적 높으나 laccase활성이 전혀 나타나지 않는 LSK-27 균주로 lignosulfonate를 처리하였다. LKY-7 과 C. versicolor-13 균주에서는 lignosulfonate의 중합화 현상이 관찰되었으며 중합화는 laccase 활성 과 비례하는 것으로 나타났다. LSK-27 균주에서는 lignosulfonate의 고분자 영역이 분해되면서 탈중합화가 일어났으며 리그닌 분해 효소로는 manganese peroxidase만 검출되었다. 보조기질로 glucose를 첨가한 결과, LKY-7 균주에서는 laccase 활정이 각소하면서 중합화 현상이 어느 정도 감소하였으나 C. versicolor-13 균주는 laccase 활성의 증가와 함께 중합화도 촉진되는 것으로 나타났다. 또한 LSK-27 균주에서도 glucose 첨가에 의해 manganese peroxidase 활성이 증가되면서 lignosulfonate의 중합화가 관찰되었다. lignosulfonate 중합화에는 laccase 뿐만 아니라 manganese peroxidase도 관여하며 보조기질로서 탄소원의 종류도 영향을 미칠것으로 검토되었다.

• Journal of Microbiology
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• v.43 no.6
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• pp.569-571
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• 2005

White-rot fungi have the following enzyme systems for lignin degradation: laccase, lignin peroxidase and manganese peroxidase. There are other types of peroxidases related to lignin degradation, one of which we have cloned a cDNA gene of manganese-repressed peroxidase (MrP) in Trametes versicolor isolated in South Korea. The mrp transcript level has been decreased by $1{\mu}M\;of\;Mn^{2+}$.

• Bulletin of the Korean Chemical Society
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• v.17 no.10
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• pp.929-934
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• 1996

The electrochemistry and the reaction of non-μ-oxo dimer-forming [5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrinato] manganese(Ⅲ) chloride [(Cl8TPP)MnⅢCl] with tetraethylammonium hydroxide in water [-OH(H2O)] have been investigated by electrochemical and spectroscopic methods under anaerobic conditions. The stronger autoreduction of (C18TPP)MnⅢCl by -OH(H2O) in comparison with (Me12TPP)MnⅢCl by -OH(CH3OH) in MeCN is explained as the influence of electronic effects on substituted phenyl groups bonded to meso-position of porphyrin ring and the positive shift of reduction potential (-0.11 V) for (C18TPP)MnⅢCl. The autoreduction of manganese(Ⅲ) porphyrin to manganese (Ⅱ) by this process is only observed when one axial position is occupied by a ligating solvent and OH- coordinates the other axial site. The results are discussed in relation to the mechanisms for the reduction of manganese(Ⅲ) porphyrin.

• Journal of the Korean institute of surface engineering
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• v.48 no.2
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• pp.56-61
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• 2015

In this study, the wear performance of manganese phosphate coating on SM45C with addition agent of Tartaric acid and Citric acid were investigated. The Surface morphology of manganese phosphate coating was examined by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectroscopy (EDS). It is found that Mn, P, Fe, O and C. The crystal structure and thee composition was analysis and determined by using XRD. The XRD results indicated that manganese phosphate coatings are mainly composed of $(Mn,Fe)_5H_2(PO_4)_44H_2O$ and consists of a lot of close packed lump crystalline. Based on the time dependence of morphology and the weight of manganese phosphate coating, it shows that the phosphating process mainly includes three stages: corrosion of the substrate, creation and growth of phosphate crystal nucleus and thickening of manganese phosphate coating. The wear tests were performed in a ball on disc apparatus as per ASTM G-99 Standard. It was showed that the initial wear was quite high followed by low sludge.

• Ocean and Polar Research
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• v.36 no.4
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• pp.455-463
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• 2014

This paper presents data from performance tests carried out to assess a manganese nodule crusher. Manganese nodules should be crushed into smaller pieces in order to assure the slurry flow of the lifting system. Both artificial nodules and real manganese nodules are used to evaluate nodule breaking ability of the crusher. The crushing performance of the crusher depends on the flow rate and pressure of the power transmission device. The size of the crushed manganese nodules also depends on the shape of the crushing drum. In this paper, several comparative tests are carried out to evaluate and improve the crushing performance and find the optimal design point of the crusher.

• Ocean and Polar Research
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• v.32 no.4
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• pp.489-499
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• 2010

The securing of raw material is an important requirement for economic development. Many countries, including Korea, actively seek out a stable supply of minerals such as manganese. Manganese nodules are rock concretions on the sea bottom formed of concentric layers of iron and manganese hydroxides around a core and include several strategic minerals necessary for economic development. In particular, the manganese nodule development project (MNDP) plays an important role in the Korean national economy. This study attempts to apply input-output (I-O) analysis in investigating the economic impacts of the MNDP in the Korean national economy. A static I-O framework was employed, focusing on four topics in its application; the production-inducing impacts, the value-added-inducing impacts, the employment-inducing impacts and R&D-inducing impacts of MNDP investments on other sectors. To this end, several versions of the demand-driven models are utilized. In addition, inter-industry linkage analysis is performed to obtain information on the forward and backward linkage effects of industries, including MNDP, to quantify the strength of causation among these industries.

• Journal of the Mineralogical Society of Korea
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• v.5 no.1
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• pp.1-5
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• 1992

The manganese oxide ores in the Taebaeg Mt. region have been formed by supergene weathering of the primary hydrothermal or sedimentary manganese ores. The supergenesis is controlled by the physical chemistry of the descending groundwater in the supergene zone. It includes the fundamental geological processes, such as dissolution, oxidation, transportation, precipitation, and crystallization and recrystallization. However, the fundamental mechanisms for the formation of various manganese oxide minerals are 1) replacement, 2) precipitation from solution, and 3) solid state crystallization and recrystallization. Various textures and structures of ores have been formed by these processes. Detailed paragenetic sequence of manganese oxide minerals in each ore deposit is summerized.