• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.36
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• pp.23-30
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• 1995

생활용품을 포함한 제조산업에 관계되는 환경오염 문제가 심각한 국내문제로 제시되어 왔으며, 제혁산업은 심각한 환경문제를 야기 시키고 있다. 본 연구는 Bio-tech 피혁가공제로 Lupin LE-10 을 개발하여 탈모공정에 적용하고자 하며, 화학적 탈모방법과 비교를 통하여 Lupin LE-10 탈모 방법의 여러 가지 장점의 검토를 하고자 한다. 따라서, 본 연구는 개발한 Bio-tech 피혁가공제를 효해공정과 수적공정에 적용하여 Lupin LE-10의 유용성과 제혁산업으로부터 야기하는 환경문제의 개선, 가죽의 수율과 물성증진에 기여하고자 한다.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.8 no.2
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• pp.119-128
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• 2022

2-Dimensional inorganic nanoparticles with high surface area and ion-exchangeable properties have been continuously growing based on nanotechnology in the field of nanomedicine. Among one of the 2-D nanoparticles, layered double hydroxide (LDH) has been intensively explored as drug delivery due to its low toxicity, enhanced cellular permeability, and high drug loading capacity. Moreover, controllable chemical composition makes possible varying isomorphic layered materials for therapy and imaging of diseases. In this review, specific structural characteristics of LDH were introduced, and its potential for application as a biocompatible therapeutic agent and diagnostic one was addressed in nuclear medicine, one of promising fields in nanomedicine.

• Journal of Microbiology and Biotechnology
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• v.17 no.10
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• pp.1727-1732
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• 2007

Phenylacetic acid (PAA) is produced by many bacteria as an antifungal agent and also appears to be an environmentally toxic chemical. The object of this study was to detect PAA using Pseudomonas putida harboring a reporter plasmid that has a PAA-inducible promoter fused to a green fluorescent protein (GFP) gene. Pseudomonas putida KT2440 was used to construct a green fluorescent protein-based reporter fusion using the paaA promoter region to detect the presence of PAA. The reporter strain exhibited a high level of gfp expression in minimal medium containing PAA; however, the level of GFP expression diminished when glucose was added to the medium, whereas other carbon sources, such as succinate and pyruvate, showed no catabolic repression. Interestingly, overexpression of a paaF gene encoding PAA-CoA ligase minimized catabolic repression. The reporter strain could also successfully detect PAA produced by other PAA-producing bacteria. This GFP-based bioreporter provides a useful tool for detecting bacteria producing PAA.

• Current Research on Agriculture and Life Sciences
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• v.31 no.4
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• pp.250-255
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• 2013

As a renewable nanomaterial, cellulose nanocrystal (CNC) isolated from wood grants excellent mechanical properties in developing high performance nanocomposites. This study was undertaken to compare the reinforcing efficiency of two different CNCs, i.e., cellulose nanowhiskers (CNWs) and cellulose nanofibrils (CNFs) from hardwood bleached kraft pulp (HW-BKP) as reinforcing agent in polyvinyl alcohol (PVA)-based nanocomposite. The CNWs were isolated by sulfuric acid hydrolysis while the CNFs were isolated by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation. Based on measurements using transmission electron microscopy, the individual CNWs were about $6.96{\pm}0.87nm$ wide and $178{\pm}55nm$ long, while CNFs were $7.07{\pm}0.99nm$ wide. The incorporation of CNWs and CNFs into the PVA matrix at 5% and 1% levels, respectively, resulted in the maximum tensile strength, indicating different efficiencies of these CNCs in the nanocomposites. Therefore, these results suggest a relationship between the reinforcing potential of CNCs and their physical characteristics, such as their morphology, dimensions, and aspect ratio.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.923-928
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• 2012

Optimizing a water-phase suspending system is very important to manufacture high-quality suspension polymerized toners. Therefore, in this study, the effects of the molar ratio of calcium hydroxide ($CaOH_2$)/phosphoric acid ($H_3PO_4$)(Ca/P), which were used as inorganic suspending agents, and pH of the water-phase on the characteristics of styrene-based suspension polymerized toners were mainly investigated. At first, the water-phase was fixed to neutral condition (pH=7.5) and Ca/P molar ratio was changed from 1.5:1 to 1.76:1. As a result, an ideal calcium phosphate (hydroxyapatite) was prepared at the Ca/P molar ratio of 1.73:1 and polymerized toners prepared at this condition showed good particle size distribution, circularity and charging characteristic. Based on this result, Ca/P molar ratio was fixed to 1.73:1 and pH of the water-phase was changed to weak acidic (pH=5.5) and weak basic (pH=9.5) conditions. As a result, polymerized toners prepared under the weak acidic condition showed very good particle size distribution, circularity and charging characteristic along with excellent printing quality. High-quality suspension polymerized toners could be prepared via optimizing Ca/P molar ratio and pH of the water-phase.

• The Journal of Engineering Geology
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• v.33 no.3
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• pp.371-388
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• 2023

A stratum with a complex composition and a distributed low-permeability soil layer is difficult to remediate quickly because the soil remediation does not proceed easily. For efficient purification, the permeability should be improved and the soil remediation agent (H₂O₂) should be injected into the contaminated section to make sufficient contact with the TPH (Total petroleum hydrocarbons). This study analyzed a method for crack formation and effective delivery of the soil remediation agent based on pneumatic fracturing, plasma blasting, and vacuum suction (the PPV method) and compared its improvement effect relative to chemical oxidation. A demonstration test confirmed the effective delivery of the soil remediation agent to a site contaminated with TPH. The injection amount and injection time were monitored to calculate the delivery characteristics and the range of influence, and electrical resistivity surveying qualitatively confirmed changes in the underground environment. Permeability tests also evaluated and compared the permeability changes for each method. The amount of soil remediation agent injected was increased by about 4.74 to 7.48 times in the experimental group (PPV method) compared with the control group (chemical oxidation); the PPV method allowed injection rates per unit time (L/min) about 5.00 to 7.54 times quicker than the control method. Electrical resistivity measurements assessed that in the PPV method, the diffusion of H₂O₂2 and other fluids to the surface soil layer reduced the low resistivity change ratio: the horizontal change ratio between the injection well and the extraction well decreased the resistivity by about 1.12 to 2.38 times. Quantitative evaluation of hydraulic conductivity at the end of the test found that the control group had 21.1% of the original hydraulic conductivity and the experimental group retained 81.3% of the initial value, close to the initial permeability coefficient. Calculated radii of influence based on the survey results showed that the results of the PPV method were improved by 220% on average compared with those of the control group.

• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.89-94
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• 2013

Layered $Li_{1+x}(Mn_{0.4}Ni_{0.4}Fe_{0.2})_{1-x}O_2$ (0 < x < 0.3) solid solutions were synthesized using solgel method with adipic acid as chelating agent. Structural and electrochemical properties of the prepared powders were examined by means of X-ray diffraction, Scanning electron microscopy and galvanostatic charge/discharge cycling. All powders had a phase-pure layered structure with $R\bar{3}m$ space group. The morphological studies confirmed that the size of the particles increased at higher x content. The charge-discharge profiles of the solid solution against lithium using 1 M $LiPF_6$ in EC/DMC as electrolyte revealed that the discharge capacity increases with increasing lithium content at the 3a sites. Among the cells, $Li_{1.2}(Mn_{0.32}Ni_{0.32}Fe_{0.16})O_2$ (x = 0.2)/$Li^+$ exhibits a good electrochemical property with maximum initial capacity of 160 $mAhg^{-1}$ between 2-4.5 V at 0.1 $mAcm^{-2}$ current density and the capacity retention after 25 cycles was 92%. Whereas, the cell fabricated with x = 0.3 sample showed continuous capacity fading due to the formation of spinel like structure during the subsequent cycling. The preparation of solid solutions based on $LiNiO_2-LiFeO_2-Li_2MnO_3$ has improved the properties of its end members.

• Clean Technology
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• v.27 no.2
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• pp.124-131
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• 2021

As declarations of carbon neutrality are spreading throughout the world, much research is being conducted on biodegradable polymers. In this study, nanocellulose, which comprises the largest amount of natural polymer currently available in the world, was proposed as a substitute for non-biodegradable polymers. We chose to modify the surface functional group of crystalline nanocellulose using glycidoxypropyl trimethoxysilane (GPTMS), which is a silane coupling agent, and the product was then used to form a film with low density polyethylene (LDPE). We then conducted measurements using a Fourier transform infrared spectrophotometer (FT-IR) in addition to measuring hydrophilic/lipophilicity of the surface functional group modification of crystalline nitrocellulose as well as that of a polymer composite using the hybrid nanocellulose (H-NC). For compatibility with petroleum-based polymers, the best tensile strength and transparency was found when the H-NC was reacted at pH 14 and 1 wt% compared with LDPE. From the test results, we found that it is possible to modify the surface functional groups of nanocellulose using a silane coupling agent. In addition, the high compatibility of nanocellulose with petroleum-based polymers is expected to help in reaching carbon neutrality by reducing the use of fossil fuels.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.2753-2758
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• 2012

Rubia cordifolia Linn, which belongs to the Rubiaceae family, is a well-known herb used in Ayurvedic medicine. In the present study, we investigated the influence of a methanolic extract (RC) on the induction of apoptosis in HEp-2 (human laryngeal carcinoma) cell line, as evidenced by cytotoxicity, morphological changes and modification in the levels of pro-oxidants. Inhibition of cell proliferation and lactate dehydrogenase (LDH) release increased in a time and dose-dependent manner. Further, reduced glutathione (GSH), glutathione transferase (GST) and protein levels decreased and lipid peroxidation increased significantly on RC treatment in a dose dependent manner when compared to controls. Based on the results we determined the optimal dose as 30mg/ ml and the apoptotic effect of RC extract (30 mg/ml) on HEp-2 cells was confirmed by fluorescent microscopy and transmission electron microscopy (TEM) based on morphological and ultrastructural changes. RC extract suppressed the proliferation of HEp-2 oral cancer cells inducing apoptotic cell death in vitro. These results point to potential of RC extract as an agent for the treatment of laryngeal squamous cell carcinoma.

• Journal of the Korean Ceramic Society
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• v.52 no.5
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• pp.389-394
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• 2015

Direct reduced iron was made using an electric furnace. The reduction ratio of direct reduced iron varied depending on the grade of iron ore. Coal played an important role as a reducing agent in making the direct reduced iron. The coal must contain a suitable amount of volatile components having high calorie values and low impurity content. In this study, oxidized pellets were directly reduced using anthracite as a reductant in an electric furnace. Direct reduction behaviors of hematite and magnetite pellets were confirmed in a coal-based experiment. Reduction behaviors were demonstrated by analyzing the chemical compositions, measuring the reducibility, and observing the phase changes and microstructure. The superior reducibility of hematite pellets can be ascribed to their high effective diffusivity, which is due to their high porosity. The quickly after reducing for 40min and achieves a high value at the end of the reduction.