• Journal of the Korean Electrochemical Society
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• v.25 no.4
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• pp.134-153
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• 2022

Regardless of a trade-off relationship between energy density and safety, it is essential to improve both properties for future lithium secondary batteries. Especially, to improve the energy density of batteries further, not only thickness but also weight of separators including ceramic coating layers should be reduced continuously apart from the development of high-capacity electrode active materials. For this purpose, an attempt to replace conventional slurry coating methods with a deposition one has attracted much attention for securing comparable thermal stability while minimizing the thickness and weight of ceramic coating layer in the separator. This review introduces state-of-the-art technology on ceramic-coated separators (CCSs) manufactured by the deposition method. There are three representative processes to form a ceramic coating layer as follows: chemical vapor deposition (CVD), atomic layer deposition (ALD), and physical vapor deposition (PVD). Herein, we summarized the principle and advantages/disadvantages of each deposition method. Furthermore, each CCS was analyzed and compared in terms of its mechanical and thermal properties, air permeability, ionic conductivity, and electrochemical performance.

• Clean Technology
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• v.29 no.3
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• pp.185-192
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• 2023

This study was conducted to obtain basic process simulation data before conducting pyrolysis experiments for the development of a thermochemical conversion system by recirculation of heat carrier and gases thereby. In this study, polypropylene (PP) was used as a pyrolysis sample material as an alternative to waste plastics, and fluid sand was used as a heat transfer medium in the system. Manganese (Mn) was chosen as the catalyst for the pyrolysis experiment, and the catalyst pyrolysis was performed by impregnating it in the sand. The basic properties of PP were analyzed using a thermogravimetric analyzer (TGA), and liquid oil was generated through catalytic pyrolysis under a nitrogen atmosphere at 600℃. The carbon number distribution of the generated liquid oil was confirmed by GC/MS analysis. In this study, the effects of the presence and the amount of Mn loading on the yield of liquid oil and the distribution of hydrocarbons in the oil were investigated. When Mn/sand was used, the residue decreased and the oil yield increased compared to pyrolysis using sand alone. In addition, as the Mn loading increased, the ratio of C₆~C₉ range gasoline in the liquid oil gradually increased, and the distribution of diesel and heavy oil with more carbon atoms than C₁₀ in the oil decreased. In conclusion, it was found that using Mn as a catalyst and changing the amount of Mn could increase the yield of liquid oil and increase the gasoline ratio in the product.

• Clean Technology
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• v.29 no.3
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• pp.163-171
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• 2023

Hydrogen has been gaining a lot of attention as a possible clean energy source that can aid in reaching carbon neutrality. Currently, hydrogen production has relied on the steam reforming of fossil fuels. However, due to the carbon dioxide emissions caused by this process, hydrogen production based on the steam reforming of bio-oil derived from biomass has been proposed as an alternative approach. In order to use this alternative approach efficiently, one of the key issues that must be overcome is that the complexity of bio-oil, which has a large molecular weight and diverse functional groups of hydrocarbons, promotes the catalytic deactivation of nickel-based catalysts. In this review, research efforts to improve nickel-based catalysts for the steam reforming of bio-oil have been discussed in terms of the active phase, support, and promoters. The active phases are involved in activating C-C and C-H bonds of high-molecular-weight hydrocarbons, and noble and transition metals can be utilized. In terms of the support and promoters, the catalytic deactivation of Ni-based catalysts can be inhibited by utilizing reactive lattice oxygen for support or by suppressing the acidity. The development of active and stable Ni-based reforming catalysts plays a critical role in clean hydrogen production based on bio-oils.

• Korean Journal of Heritage: History & Science
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• v.56 no.1
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• pp.100-116
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• 2023

The Sinamsa Temple was built in the late Goryeo Dynasty and a gilt-bronze seated Buddha is enshrined in Geungnakjeon hall in the precinct. Various damages occurred in the gilt layer of the Buddha, such as peeling of the gilt layer and deteriorating gloss. In the study, the conservation conditions of the inside and outside on the statue were accurately investigated, and the making technique was interpreted through the material characteristics and non-destructive diagnosis of the statue. As a result, it is estimated that gold-gilding layer is pure gold, coloration pigment of black is carbon, green is malachite, atacamite and verdigris, red is red lead and cinnabar, respectively. In the deterioration evaluation, peeling, cracking, break out and exfoliation of the gilt layer are confirmed as damages, but the conservation condition is relatively wholesome. However, the gloss of the gilt layer is calculated to be wider in the poorer part than the maintenance part. The ultrasonic velocity of the statue was calculated to be 1,230 to 3,987 (mean 2,608) m/s and showed a relatively wide range. In infrared thermography, peeling was not confirmed, and no special bonding marks were found. In endoscope, some biological damage and corrosion were observed on the surface of the internal metal, and sealed artifacts were identified. Manufacturing technique based on the study, it is considered that the gilt-bronze seated Buddha was cast at once, and the mold was inverted to inject molten metal.

• Progress in Superconductivity and Cryogenics
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• v.25 no.2
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• pp.10-13
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• 2023

High-T_C superconductivity (HTSC) has been the central issue in the field of condensed matter physics for decades. An essential part of the research on superconductivity is finding new exotic superconductors. It was recently suggested that Ir-substituted La_0.7Sr_0.3MnO₃ (LSMIO) is a new high-T_C superconductor. However, systematic studies to experimentally verify the superconductivity have not been done. Here, we report the growth processes of LSMIO thin films and their electrical transport properties. We observed a clear negative correlation between the intensity of the laser utilized for film deposition and the Curie temperature of the deposited film. We attributed this effect to the suppression of Sr concentration in the LSMIO films as the laser intensity increased. However, our LSMIO films show conventional ferromagnetism instead of HTSC. To realize the HTSC in LSMIO systems, further exploration of diverse compositions of LSMIO compounds is essential.

• Resources Recycling
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• v.32 no.6
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• pp.45-53
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• 2023

This study discussed the trend and future strategy of adsorption technology R&D to effectively recover ammonia emitted from the livestock fields. A proper ammonia adsorbent should incorporate acidic or hydrogen bonding functional groups on the surface, as well as a high specific surface area and a good surface structure appropriate for ammonia adsorption. Activated carbon and minerals such as zeolite have widely been used as ammonia adsorbents, but their adsorption effects are generally low, so any improvement through surface modification should be necessary. For example, incorporation of metal chloride included in a porous adsorbent can promote ammonia adsorption effectiveness. Recently, new types of adsorbents such as MOFs (Metal-Organic Frameworks) and POPs (Porous Organic Polymers) have been developed and utilized. They have shown very high ammonia adsorption capacity because of adjustable and high specific surface area and porosity. In addition, Prussian Blue exhibited high ammonia adsorption and desorption performance and selectivity. This looks relatively advantageous in relation to the recovery of ammonia from livestock waste discharge. In the future, further research should be made to evaluate ammonia adsorption/desorption efficiency and purity using various adsorbents under conditions suitable for livestock sites. Also, effective pre- and/or post-treatment processes should be integrated to maximize ammonia recovery.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.2
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• pp.73-77
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• 2024

The spinel-type oxide (Ni_x, Mn_y, Co_3-x-y)O₄ (NMC) is widely utilized as a material for temperature sensors with a negative temperature coefficient (NTC), finding applications across various industries including electric vehicle battery management systems. Typically, NMC is manufactured using solid-state reaction methods employing powders of Ni, Mn, and Co compounds, with the densification process through sintering recognized as a crucial factor determining the electrical properties of the temperature sensor material. In this study, NMC pellets were synthesized via solid-state reaction and their crystallographic and microstructural characteristics were investigated. Also, the activation energy for densification behavior during the sintering process was determined. According to the analysis results, the room temperature resistance of the NMC pellets was measured at 10.03 Kohm, with the sensitivity parameter, B-value, recorded at 3601.8 K, indicating their potential applicability as temperature sensors across various industrial fields. Furthermore, the activation energy for densification was found to be 273.3 ± 0.4 kJ/mol, providing valuable insights into the thermodynamic aspects of the sintering process of the NMC.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.3
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• pp.271-279
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• 2008

Polymetallic sulphides means hydrothermally formed deposits of sulphide minerals which contain concentrations of metals including, inter alia, copper, lead, zinc, gold and silver. Nautilus is the first company to commercially explore the seafloor polymetallic sulphide deposits. The Company holds exploration licences and exploration applications for more than 370,000 $km^2$ in the jurisdictional seas of Papua New Guinea, Fiji, Tonga, the Solomon Islands and New Zealand along the western Pacific Ocean's Rim of Fire. Neptune Minerals is also a leading explorer and developer in this field, with exploration licences awarded totalling more than 270,000 $km^2$ in the territorial seas or EEZ of New Zealand, Papua New Guinea and the Federated States of Micronesia. These two companies now carry out the most active investment activities for seafloor polymetallic sulphide deposits with a goal of commercial production by 2010. China and Japan carry out exploration activities for the seafloor polymetallic sulphide deposits to secure supplies of strategic metals. China carries out national R&D projects relating to deep sea mineral resources in the world ocean through China Ocean Mineral Resources R&D Association(COMRA). And Japan investigates her own EEZ for exploration of the seafloor polymetallic sulphide deposits. In consideration of aforementioned international activities of coastal nations as well as private companies for exploring the sulphide deposits, Korea shall prepare strategic plans : First, consolidation of the authorities concerned and legislative support; second, determination of main entity of the project; third, securing government's decisive investment of sufficient budget; and lastly, establishment of the mid, long-term plan for development of seafloor polymetallic sulphides deposits.

• Clean Technology
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• v.30 no.2
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• pp.105-112
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• 2024

Globally, the demand for electric vehicles has surged due to greenhouse gas regulations related to climate change, leading to an increase in the production of used batteries as a consequence of the battery life issue. This study aims to selectively leach and recover valuable metal lithium from the cathode material of spent LFP (LiFePO₄) batteries among lithium-ion batteries. Generally, the use of inorganic acids results in the emission of toxic gases or the generation of large quantities of wastewater, causing environmental issues. To address this, research is being conducted to leach lithium using organic acids and other leaching agents. In this study, selective leaching was performed using the organic acid methane sulfonic acid (MSA, CH₃SO₃H). Experiments were conducted to determine the optimal conditions for selectively leaching lithium by varying the MSA concentration, pulp density, and hydrogen peroxide dosage. The results of this study showed that lithium was leached at approximately 100%, while iron and phosphorus components were leached at about 1%, verifying the leaching efficiency and the leaching rates of the main components under different variables.

• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.297-302
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• 2001

To compare the relationship between the vertical distribution of heavy metals in paddy soil and soil pH near four abandoned metal mines, 40 paddy surface soils $(0{\sim}15\;cm)$ and 12 soils with soil depths ($0{\sim}20$, $20{\sim}40$, $40{\sim}60$, $60{\sim}80$ and $80{\sim}100$ cm) were collected. Both total and extractable heavy metal contents in soils were analyzed after acid digestion $(HNO_3:HClO_4:H_2SO_4)$ and 0.1 N-HCl extraction, respectively. The 0.1 N-HCl fraction ratio over total contents of Cd, Cu, Pb, and Zn were 57, 30, 23, and 19% respectively. Vertical distribution of heavy metals varied considerably among the different mines. In Choil mine, there was no difference in concentrations of all the metals with soil layers. However, Cu and Pb contents in Gahak mime were high at $0{\sim}20\;cm$ depth, and Zn was high at $0{\sim}40\;cm$ depth. In Sinyemi mine, Cd and Cu contents were high at $0{\sim}40\;cm$ depth. Cd, Cu, and Pb contents in Okcheon mine were high through all soil profiles up to 100 cm soil depth. The 0.1 N-HCl fraction ratio over total contents of heavy metals with soil layers were very high at $0{\sim}20\;cm$ depth. As soil depth increased, fraction ratio of heavy metals decreased at the high soil pH (Gahak, Sinyemi, and Choil mines). However, the ratios of Cd, Cu, and Pb in Okcheon mine, having a relatively lower soil pH than other sites, were relatively similar through all the soil profiles up to 100 cm soil depth. Therefore, it was estimated that the mobility and availability of heavy metals in soils were affected by soil pH.