• Resources Recycling
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• v.24 no.4
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• pp.32-37
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• 2015

Cobalt is abundant only in some countries including Democratic Republic of the Congo. It would be necessary to secure overseas Co ores and Co extraction technology. Two kinds of matte varying the sulfur content were manufactured by smelting reduction of Co concentrate containing ~8 wt% Co, ~19 wt% Cu, and ~3 wt% Fe. The amount of Co, Cu and Fe was concentrated to 19~21 wt%, 39~41 wt%, and 7~9 wt% respectively in the resulting matte. High-pressure leaching of matte was performed in an autoclave with considering the effect of oxidizing agent, $H_2SO_4$ concentration as a lixiviant, and the amount of sulfur added to the matte. An oxidizing agent (oxygen) is necessary to improve Co leaching efficiency enabling usage of a dilute $H_2SO_4$ leaching agent. An increase in $H_2SO_4$ concentration prevents selective leaching of Co, and the sulfur content in matte has a minor influence on the Co leaching efficiency.

• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.1083-1096
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• 2020

Global attention to the greenhouse gas emissions from deforestation and forest degradation is increasing. There is a growing recognition of reducing emission from deforestation and forest degradation plus (REDD+) as an effective way to reduce greenhouse gas emissions in the forestry sector. The Republic of Korea is implementing REDD+ pilot projects in four Southeast Asian countries as part of its efforts to reduce greenhouse gas emissions. This study evaluates countries with the potential to become priority partner countries for Korea's REDD+ programs, using the following five criteria: The first criterion is that a country should include the forest sector and REDD+ in its national plan for reducing greenhouse gas (GHG) emissions. The second and third criteria refer to an average forest coverage rate of over 44% and a forest change rate of over - 0.1%, among the countries with forest cover of more than 10 million ha. The fourth criterion is that the country should meet the Forest Reference Emission Level requirements, one of the four elements of the Warsaw REDD+ Framework. The fifth criterion is that the country should have bilateral relations with the Republic of Korea in forestry while at the same time be a partner country for cooperation on climate change as well as a REDD+ pilot country. Based on our evaluation, we conclude that the first priority countries are Indonesia, Cambodia, and Myanmar. The second priority countries include Brazil, Ecuador, and Peru. Finally, the third priority countries are Columbia, Congo, and Mozambique. This study suggests that for the selection of priority partner countries, Korean REDD+ programs should center on existing REDD+ pilot countries.

• Journal of Powder Materials
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• v.29 no.3
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• pp.252-261
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• 2022

Cobalt is a vital metal in the modern society because of its applications in lithium-ion batteries, super alloys, hard metals, and catalysts. Further, cobalt is a representative rare metal and is the 30th most abundant element in the Earth's crust. This study reviews the current status of cobalt extraction and recycling processes, along with the trends in its production amount and use. Although cobalt occurs in a wide range of minerals, such as oxides and sulfides of copper and nickel ores, the amounts of cobalt in the minerals are too low to be extracted economically. The Democratic Republic of Congo (DRC) leads cobalt mining, and accounts for 68.9 % of the global cobalt reserves (142,000 tons in 2020). Cobalt is mainly extracted from copper-cobalt and nickel-cobalt concentrates and is occasionally extracted directly from the ore itself by hydro-, pyro-, and electro-metallurgical processes. These smelting methods are essential for developing new recycling processes to extract cobalt from secondary resources. Cobalt is mainly recycled from lithium-ion batteries, spent catalysts, and cobalt alloys. The recycling methods for cobalt also depend on the type of secondary cobalt resource. Major recycling methods from secondary resources are applied in pyro- and hydrometallurgical processes.

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.305-313
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• 2010

Mineralogical characteristics of Cu-Co ores from the Central African Copperbelt in the Democratic Repblic of Congo are studied using powder X-ray diffractometer, general area detector X-ray diffractometer, and electron proble microanalyzer. Black ores are mainly composed of heterogenite (cobalt oxide/hydroxide mineral) and malachite (copper carbonate mineral), whereas green ores are only composed of malachite. Heterogenite shows very bright white color under the reflected microscope, and belongs to 3R polytype, because it has d-spacings at $4.39{\AA}$ and $2.316{\AA}$. Since NiO and $Fe_20_3$ content of heterogenite are lower than those of 3R polytype from other localities, it cannot completely exclude the presence of 2H polytype in heterogenite from this study. Malachite is light grey color under the reflected microscope with approximate chemical formula of $Cu_{1.97}Co_{0.02}Fe^{2+}{_{0.01}}CO_3(OH)_2$. Heterogenite and malachite were probably formed at the supergene emichment stage, the last mineralization stage in the Central African Copperbelt. Cobalt seems to be much more emiched in the black supergene (oxy)hydroxide ore than those in the primary sulfide ore.

• Journal of Forest and Environmental Science
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• v.36 no.3
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• pp.175-186
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• 2020

This study approaches, from a floristic perspective, the under-researched human-primate competition for forest resources. Investigating the human impact on fruit trees edible for Kinda baboons (Papio kindae Lönnberg), we have collated dietary data on a free-ranging troop and floristic information on two forest sites of the Kundelungu National Park (KNP), Democratic Republic of Congo: the relatively intact Integral Zone (IZ) and the human-disturbed Annex Zone (AZ). Trees with DBH≥10 cm have been identified, counted and measured throughout 22 sample plots (11 per site), each measuring 1,000 ㎡. A total of seven woody species whose fruits are eaten by Kinda baboons were recorded. Four of them, namely the Sycamore fig Ficus sycomorus L., the Mobola plum Parinari curatellifolia Planch. ex Benth, the Kudu berry Pseudolachnostylis maprouneifolia Pax and the Monkey orange Strychnos innocua Delile were found in both sites, while the Large-leaved jackal-berry Diosyros kirkii Hiern and the Buffalo thorn Ziziphus mucronata Willd. were exclusively in the IZ, and Strychnos cocculoides Baker only in the AZ. Compared to the IZ, the AZ had lower values of stem density, species richness and diversity indices, suggesting a negative human impact on baboon-edible trees, in line with our hypothesis. Moreover, as was expected, human activities decreased the abundance of larger baboon-edible fruit trees. However, the size-class distribution of P. curatellifolia depicted a reverse J-curve in the AZ. The abundant younger P. curatellifolia trees remaining in that human-disturbed site constitute an important food stock for baboons, if well preserved. These results also illustrate the critical role of rangers' patrols, formerly more frequent (and presumably efficient) in the IZ than in the AZ of the Park. Their implications on baboons and miombo forests are discussed from both the research and conservation perspectives.

• Journal of Veterinary Science
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• v.22 no.3
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• pp.35.1-35.13
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• 2021

Background: African swine fever (ASF) is an infectious viral disease of domestic pigs that presents as a hemorrhagic fever, and for which no effective vaccine is available. The disease has a serious negative social and economic impact on pig keepers. There is limited information on the potential risk factors responsible for the spread of ASF in South Kivu. Objective: The aim of this study was to determine the potential risk factors associated with ASF infection in suspected ASF virus (ASFV)-infected pigs. Methods: We sampled whole blood from 391 pigs. Additionally, 300 pig farmers were interviewed using a structured questionnaire. Viral DNA was detected by using the real-time polymerase chain reaction technique. Results: The majority of pigs sampled, 78% (95% confidence interval [CI], 74.4-82.6), were of local breeds. Over half, 60.4% (95% CI, 55.5-65.2), were female, and most of them, 90.5% (95% CI, 87.6-93.4), were adult pigs (> 1 year old). Viral DNA was detected in 72 of the 391 sampled pigs, indicating an overall infection rate of 18.4% (95% CI, 14.5-22.4). Multivariable logistic regression analysis revealed several risk factors positively associated with ASFV infection: feeding with swill in pen (odds ratio [OR], 3.8; 95% CI, 2.12-6.77); mixed ages of pigs in the same pen (OR, 3.3; 95% CI, 1.99-5.57); introduction of new animals to the farm (OR, 5.4; 95% CI, 1.91-15.28). The risk factors that were negatively (protective) correlated with ASFV positivity were the presence of male animals and the use of an in-pen breeding system. Conclusion: Local pig farmers should be encouraged to adopt proper husbandry and feeding practices in order to increase the number of ASF-free farms.

• Journal of Environmental Science International
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• v.23 no.8
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• pp.1463-1468
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• 2014

An exotic parasitic wasp Anisopteromalus apiovorus of Pteromalidae was newly recorded in Korea. Specimens of this species have been collected in Gimhae of Korea since 2012. External morphology of this species was described in detail and diagnostic differences of this species from the related species and the host insect were also given. The funicle segments of female antennae are 1.2 to 1.5 times longer than those of Anisopteromalus calandrae, an sister species. Body color is gold-glossy black and with dense creamy-white hairs on the surface. This exotic species has been originated from the African continent including Democratic Republic of Congo and Cote d'Ivoire, and then intruded into other countries, for instance, Korea. This is the first distribution record of this species except the country of origin after original description as a new species. Although little is known about the life history or ecology of this species, we found that a new host of this small parasitic wasp is Lasioderma serricorne of coleoptera through present study. And this species possibly be a new agent of biological control for economic pests. It was presumed that the invasion of Anisopteromalus apiovorus into Korea was prior to November of 2012.

• Safety and Health at Work
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• v.5 no.3
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• pp.131-135
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• 2014

Background: Cassava and corn milling is a growing small-scale enterprise in Africa. We aimed to determine the incidence of hand-arm musculoskeletal complaints among vibration-exposed Congolese cassava and corn millers in the previous 12 months. Methods: A cross-sectional study was conducted, prior to a follow-up study, from March to May 2013 among cassava/corn millers in Lubumbashi, Democratic Republic of Congo, in which 365 millers age-matched to 365 civil workers anonymously answered a questionnaire. Results: Overall incidence of hand-arm musculoskeletal complaints was 25.8% in millers (vs. 5.2% in civil workers; p < 0.001). The risk of experiencing musculoskeletal symptoms was seven times higher in millers [vs. civil workers; odds ratio (OR) = 7.10; 95% confidence interval (CI): 4.03-12.50; p < 0.0001]; 2.4 times higher in smoking millers (vs. smoking civil office workers; OR = 2.36; 95% CI: 1.42-3.88; p < 0.001); 3.6 times higher in millers with longer daily exposure (> 8 hours; vs. those working ${\leq}8$ hours; OR = 3.56; 95% CI: 1.93-3.61; p = 0.026); and 7.4 times higher in young millers (vs. older millers, OR = 7.39; 95% CI: 1.29-75.52; p < 0.001). Smoking, number of cigarettes, and daily exposure duration were positively correlated with musculoskeletal complaints. Conclusion: This study revealed a relatively high incidence of musculoskeletal complaints among African cassava and corn millers. The use of anti-vibration protective equipment and the regulation of this hazardous occupation may reduce the burden of musculoskeletal disorders in millers.

• Journal of Korean Society of Forest Science
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• v.98 no.3
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• pp.263-271
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• 2009

This study aims to identify negotiation alternatives related to Post-2012 reducing emissions from deforestation (RED) and enhancement of forest carbon stock (EFCS) activities. It also aims to recommend a negotiation strategy considering environmental integrity and national interest on the basis of estimating reduction potentials of each alternative on the assumption that tradable carbon credits play an important role as positive incentives. In order to estimate greenhouse gas (GHG) reduction potentials and income potential from RED and EFCS activities, 99 countries were selected by the Global Forest Resources Assessment of the Food and Agriculture Organization of the United Nations. A 'baseline and credit' method was applied to estimate RED activities. Gross-net and net-net methods were applied for EFCS activities. According to the results, Brazil, Indonesia, and the Democratic Republic of Congo have more potential to get positive incentives through RED, while China, Chile, and the Republic of Korea have more potential to get positive incentives through EFCS. This study suggests including both RED and EFCS activities in the boundary of policy approaches and endowment of positive incentives to consider GHG reduction potentials in the global scale and equity among developing countries. Making a discount rate application of forest management activities can be also recommended to factor out the effects of human-induced activities by EFCS activities.

• Microbiology and Biotechnology Letters
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• v.40 no.3
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• pp.190-196
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• 2012

In this study, a total of more than 1,000 bacteria, including 739 species of aerobic bacteria, 80 species of urease producing bacteria and 303 species of photosynthetic bacteria, were isolated from red-pepper field soils located in the Gyeongsan Province of the Republic of Korea. Amongst these, 158 species of aerobic bacteria, 70 species of urease producing bacteria and 228 species of photosynthetic bacteria were found to be auxin producing soil bacteria through quantification analysis with the Salkowski test. The latter groupings were then tested for antifungal activities to ${\beta}$-Glucanase and siderophore using CMC congo red agar and CAS blue agar media. In addition, the selected strains were examined for antifungal activity against various phytopathogenic fungi on PDN agar media. Six strains; BCB14, BCB17, C10, HA46, HA143, and HJ5, were noted for their ability to both produce auxin and act as antifungal substances. 16S rDNA sequence comparison analyses of these six strains identified them as Bacillus subtilis BCB14, B. methylotrophicus BCB17, B. methylotrophicus C10, B. sonorensis HA46, B. subtilis HA143, and B. safensis HJ5.