• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제45권3호
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• pp.123-128
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• 2019

Demineralized dentin matrix (DDM) has been used as a recombinant human bone morphogenetic protein-2 (rhBMP-2) carrier in many clinical trials. To optimize the clinical safety and efficacy of rhBMP-2 with DDM, efforts have been made to improve the delivery of rhBMP-2 by 1) lowering the administered dose, 2) localizing the protein, and 3) prolonging its retention time at the action site as well as the bone forming capacity of the carrier itself. The release profile of rhBMP-2 that is associated with endogenous BMP in dentin has been postulated according to the type of incorporation, which is attributed to the loosened interfibrillar space and nanoporous dentinal tubule pores. Physically adsorbed and modified, physically entrapped rhBMP-2 is sequentially released from the DDM surface during the early stage of implantation. As DDM degradation progresses, the loosened interfibrillar space and enlarged dentinal tubules release the entrapped rhBMP-2. Finally, the endogenous BMP in dentin is released with osteoclastic dentin resorption. According to the postulated release profile, DDM can therefore be used in a controlled manner as a sequential delivery scaffold for rhBMP-2, thus sustaining the rhBMP-2 concentration for a prolonged period due to localization. In addition, we attempted to determine how to lower the rhBMP-2 concentration to 0.2 mg/mL, which is lower than the approved 1.5 mg/mL.

• Membrane and Water Treatment
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• 제10권1호
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• pp.91-97
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• 2019

Application of bioretention systems in Korea is highly considered due to its minimal space requirements, appropriateness as small landscape areas and good pollutant removal and peak hydraulic flow reduction efficiency. In this study, the efficiency of two lab-scale bioretention types having different physical properties, media configuration and planted with different shrubs and perennials was investigated in reducing heavy metal pollutants in stormwater runoff. Type A bioretention systems were planted with shrubs whereas type B were planted with perennials. Chrysanthemum zawadskii var. latilobum (A-CL) and Aquilegia flabellata var. pumila (A-AP) respectively were planted in each type A bioretention reactors while Rhododendron indicum linnaeus (B-RL) and Spiraea japonica (B-SJ), respectively were planted in each type B bioretention reactors. Results revealed that the four lab-scale bioretention reactors significantly reduced the influent total suspended load by about 89 to 94% (p<0.01). Type B-RL and B-SJ reactors reduced soluble Cr, Cu, Zn, and Pb by 28 to 45% that were 15 to 35% greater than the soluble metal reduction of type A-CL and A-AP reactors, respectively. Among the pollutants, total Cr attained the greatest discharged fraction of 0.52-0.81. Excluding the effect of soil media, total Pb attained the greatest retention fraction in the bioretention systems amounting to 0.15-0.34. Considering the least discharge fraction of heavy metal in the bioretention system, it was observed that the bioretention systems achieved effectual reduction in terms of total Cu, Zn and Pb. These findings were associated with the poor adsorption capacity of the soil used in each bioretention system. The results of this study may be used for estimating the maintenance requirements of bioretention systems.

• Korean Journal of Environmental Agriculture
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• 제41권2호
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• pp.101-107
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• 2022

BACKGROUND: Soil amendment was necessary applied for the sand that had been used to root zone of green ground in golf course because of its low water retention power and cation exchangeable capacity. This study was conducted to evaluate the effect of the mixed ratio of peat moss and coconut coir as soil amendment materials on the soil physicochemical properties applied to rootzone based on sand. METHODS AND RESULTS: The soil amendments were blended at 0, 3, 5, 7 and 10% by soil volume. The pH in the peat moss treatment was lower than that of control (0% soil amendment), and pH and electrical conductivity (EC) in the coconut coir were higher. The blending ratio of peat moss was negatively correlated with pH of rootzone soil (p<0.01), and that of coconut coir positively with EC (p<0.01). As compared with control, capillary porosity, the physical factors such as air-filled porosity, total porosity, and hydraulic conductivity of rootzone soil were increased by applying peat moss and coconut coir. For correlation coefficients between percentage of soil amendments and soil physical factors, peat moss and coconut coir were positively correlated with porosity and hydraulic conductivity (p<0.01). CONCLUSION(S): These results indicated that the application of peat moss and coconut coir affected on the change of physicochemical properties of rootzone soil, and improved soil porosity and hydraulic conductivity.

• Journal of Electrochemical Science and Technology
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• 제13권1호
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• pp.128-137
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• 2022

For this study, the sol gel method was used to synthesize the spinel LiNi_0.5Mn_1.5O₄ (LNMO) electrode material. Structural, morphological, electrochemical, and kinetic aspects of the LNMO have been characterized. The synthesized LNMO was indexed with the Fd3m cubic space group. The excellent capacity retention indicates that the spinel framework of LNMO has the ability to withstand high rate charge-discharge throughout long cycle tests. The Li diffusion coefficient (D_Li) changes non-monotonically across three orders of magnitude, from 10^-9 to 10^-12 cm² s^-1 determined from GITT method. The variation of D_Li seemed to be related to three oxidation reactions that happened throughout the charging process. A small dip in D_Li at the beginning stage of Li deintercalation is correlated with the oxidation of Mn³⁺ to Mn⁴⁺. While two pronounced D_Li minima at 4.7 V and 4.75 V are due to the oxidation of Ni²⁺/Ni³⁺ and Ni³⁺/Ni⁴⁺ respectively. The depletion of D_Li at the high voltage region is attributed to the occurrence of two successive phase transformation phenomena.

• Korean Journal of Materials Research
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• 제32권4호
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• pp.210-215
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• 2022

Extensive research is being carried out on Ni-rich Li(Ni_xCo_yMn_1-x-y)O₂ (NCM) due to the growing demand for electric vehicles and reduced cost. In particular, Ni-rich Li(Ni_xCo_yMn_1-x-y-zAl_z)O₂ (NCMA) is attracting great attention as a promising candidate for the rapid development of Co-free but electrochemically more stable cathodes. Al, an inactive element in the structure, helps to improve structural stability and is also used as a doping element to improve cycle capability in Ni-rich NCM. In this study, NCMA was successfully synthesized with the desired composition by direct coprecipitation. Boron and tin were also used as dopants to improve the battery performance. Macro- and microstructures in the cathodes were examined by microscopy and X-ray diffraction. While Sn was not successfully doped into NCMA, boron could be doped into NCMA, leading to changes in its physicochemical properties. NCMA doped with boron revealed substantially improved electrochemical properties in terms of capacity retention and rate capability compared to the undoped NCMA.

• Journal of Electrochemical Science and Technology
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• 제14권3호
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• pp.293-300
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• 2023

The global energy storage markets have gravitated to high-energy-density and low cost of lithium-ion batteries (LIBs) as the predominant system for energy storage such as electric vehicles (EVs). High-Ni layered oxides are considered promising next-generation cathode materials for LIBs owing to their significant advantages in terms of high energy density. However, the practical application of high-Ni cathodes remains challenging, because of their structural and surface instability. Although extensive studies have been conducted to mitigate these inherent instabilities, a two-step process involving the synthesis of the cathode and a dry/wet coating is essential. This study evaluates a one-step β-Li₂SnO₃ layer coating on the surface of LiNi_0.8Co_0.2O₂ (NC82) via the thermal segregation of Sn owing to the solubility limit with respect to the synthesis temperature. The doping, segregation, and phase transition of Sn were systematically revealed by structural analyses. Moreover, surface-engineered 5 mol% Sn-coated LiNi_0.8Co_0.2O₂ (NC82_Sn5%) exhibited superior capacity retention compared to bare NC82 owing to the stable surface coating layer. Thus, the developed one-step coating method is suitable for improving the properties of high-Ni layered oxide cathode materials for application in LIBs.

• The Korea Journal of Herbology
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• 제38권5호
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• pp.97-103
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• 2023

Objectives : These days many people tend to prefer spicy taste. The purpose of this study was to find out the relationship between prefer spicy and physical symptoms. Methods : We examined the subjective physical condition of patients who visited L/C clinic during the period between January and June 2023 by conducting a survey. The survey was completed voluntarily, and the anonymity and confidentiality of the research data were strictly protected, and it was stated that patients could withdraw at any time if they did not want to participate. Patients who refused to complete the survey and patients with limited capacity to give consent were excluded. The survey took about 10 minutes to complete. We analyzed 248 cases who answered the survey and found that 66 patients had a high spicy preference. Results : As a result, participants with high spicy taste preference tended to have general body symptoms such as fever, sweat, and thirst; digestive symptoms such as belching, constipation, bloody stools, and abdominal distension; genitourinary symptoms such as yellowish urine, urinary retention, white fluor albus, and premenstrual tension; and neuromuscular symptoms such as edema, blepharospasm, and cold hands. Conclusion : People who have general body symptoms, digestive symptoms, genitourinary symptoms and neuromuscular symptoms described above should try to eat as little spicy food as possible and make sure they get a good balance of the five flavors.

• Journal of Electrochemical Science and Technology
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• 제14권2호
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• pp.152-161
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• 2023

Vanadium redox flow batteries (VRFBs) have been considered one of promising power sources for large scale energy storage systems (ESS) because of their excellent cycle performance and good safety. However, VRFBs still have a few challenging issues, such as poor Coulombic efficiency due to vanadium crossover between catholyte and anolyte, although recent efforts have shown promise in electrochemical performance. Herein, the vanadium complexes with various glyme ligands have been examined as active materials to suppress vanadium crossover between catholyte and anolyte, thus improving the Coulombic efficiency of VRFBs. The conventional Nafion membrane has a channel size of ca. 10 Å, whereas vanadium cation species are small compared to the Nafion membrane channel. For this reason, vanadium cations can permeate through the Nafion membrane, resulting in significant vanadium crossover during cycling, although the Nafion membrane is a kind of ion-selective membrane. In this regard, various glyme additives, such as 1,2-dimethoxyethane (monoglyme), diethylene glycol dimethyl ether (diglyme), and tetraethylene glycol dimethyl ether (tetraglyme) have been examined as complexing agents for vanadium cations to increase the size of vanadium-ligand complexes in electrolytes. Since the size of vanadium-glyme complexes is proportional to the chain length of glymes, the vanadium permeability of the Nafion membrane decreases with increasing the chain length of glymes. As a result, the vanadium complexes with tetraglyme shows the excellent electrochemical performance of VRFBs, such as stable capacity retention (90.4% after 100 cycles) and high Coulombic efficiency (98.2% over 100 cycles).

• Membrane and Water Treatment
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• 제15권1호
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• pp.21-29
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• 2024

1H,1H,2H,2H-perfluorodecytriethoxysilane (C₁₆H₁₉F₁₇O₃Si) be successfully applied to the hydrophobic modification of Al₂O₃ tubular ceramic membrane. Taking the concentration of modification solution, modification time, and modification temperature as factors, orthogonal experiments were designed to study the hydrophobicity of the composite membranes. The experiments showed that the modification time had the greatest impact on the experimental results, followed by the modification temperature, and the modification solution concentration had the smallest impact. Concentration of the modified solution 0.012 mol·L^-1, modification temperature 30 ℃ and modification time 24 h were considered optimal hydrophobic modification conditions. And the pure water flux reached 274.80 kg·m^-2·h^-1 at 0.1MPa before hydrophobic modification, whereas the modified membrane completely blocked liquid water permeation at pressures less than 0.1MPa. Air gap membrane distillation experiments were conducted for NaCl (2wt%) solution, and the maximum flux reached 4.20 kg·m^-2·h^-1, while the retention rate remained above 99.8%. Given the scarcity of freshwater resources in coastal areas, the article proposed a system for seawater desalination using air conditioning waste heat, and conducted preliminary research on its freshwater production performance using Aspen Plus. Finally, the proposed system achieved a freshwater production capacity of 0.61 kg·m^-2·h^-1.

• Journal of The Korean Society of Agricultural Engineers
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• 제66권4호
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• pp.27-39
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• 2024

Soil texture is determined by the proportions of sand, silt, and clay within the soil, which influence characteristics such as porosity, water retention capacity, electrical conductivity (EC), and pH. Traditional classification of soil texture requires significant sample preparation including oven drying to remove organic matter and moisture, a process that is both time-consuming and costly. This study aims to explore an alternative method by developing an AI model capable of predicting soil texture from images of pre-sorted soil samples using computer vision and deep learning technologies. Soil samples collected from agricultural fields were pre-processed using sieve analysis and the images of each sample were acquired in a controlled studio environment using a smartphone camera. Color distribution ratios based on RGB values of the images were analyzed using the OpenCV library in Python. A convolutional neural network (CNN) model, built on PyTorch, was enhanced using Digital Image Processing (DIP) techniques and then trained across nine distinct conditions to evaluate its robustness and accuracy. The model has achieved an accuracy of over 80% in classifying the images of pre-sorted soil samples, as validated by the components of the confusion matrix and measurements of the F1 score, demonstrating its potential to replace traditional experimental methods for soil texture classification. By utilizing an easily accessible tool, significant time and cost savings can be expected compared to traditional methods.