• Environmental Engineering Research
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• v.24 no.3
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• pp.501-512
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• 2019

The seasonal effects on the biostability of drinking water were investigated by comparing the seasonal variation of assimilable organic carbon (AOC) in full-scale water treatment process and adsorption of AOC by three filling materials in lab-scale column test. In full-scale, pre-chlorination and ozonation significantly increase $AOC_{P17\;(Pseudomonas\;fluorescens\;P17)}$ and $AOC_{NOX\;(Aquaspirillum\;sp.\;NOX)}$, respectively. AOC formation by oxidation could increase with temperature, but the increased AOC could affect the biostability of the following processes more significantly in winter than in warm seasons due to the low biodegradation in the pipes and the processes at low temperature. $AOC_{P17}$ was mainly removed by coagulation-sedimentation process, especially in cold season. Rapid filtration could effectively remove AOC only during warm seasons by primarily biodegradation, but biological activated carbon filtration could remove AOC in all seasons by biodegradation during warm season and by adsorption and bio-regeneration during cold season. The adsorption by granular activated carbon and anthracite showed inverse relationship with water temperature. The advanced treatment can contribute to enhance the biostability in the distribution system by reducing AOC formation potential and helping to maintain stable residual chlorine after post-chlorination.

• Polymer(Korea)
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• v.28 no.1
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• pp.86-91
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• 2004

Hydrogels with enhanced biocompatibility and biostability were prepared by copolymerization of 2-hydroxyethyl methacrylate (HEMA) and sodium methacrylate (SMA) at high monomer concentration to replace a sponge which has limited applications as an implant material. It was found that incorporation of SMA moiety suppressed cytotoxicity. P(HEMA-co-SMA) hydrogel prepared at SMA feed ratio of 0.05 showed minimal cytotoxicity as compared with a normal cell culture plate. The adhesion and the spreading of cells were preferred on the surface of the hydrogel prepared with SMA feed ratio of 0.01. On the other hand, the hydrogel prepared with SMA feed ratio of 0.05 showed lower cell adhesion. Histological findings revealed no evidence of significant foreign body reaction in the tissues around the copolymer hydrogels. Conclusively, it is suggested that the hydrogels prepared by copolymerization of HEMA and SMA at high monomer concentration are strong candidates for an implant material with excellent biocompatibility and biostability.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.2
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• pp.169-176
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• 2017

Dental implants are required to have biomechanical functions and biostability in order to perform authoring, pronunciation, and aesthetic functions in the oral cavity. In terms of biostability, pure titanium for medical have good biostability and no rejection in the alveolar bone. with appropriate strength in terms of strength as well as biocompatibility. In recent years, various surgical methods and devices have been developed to improve the convenience and safety of the procedure. However, as the number of procedures increases, the screw loosening of the abutment screw connecting the artificial root and the abutment There are many reports of artificial root and abutment fracture. Fig. 1 is an example of a case where the upper part of the abutment screw is arbitrarily modified to remove the abutment by the abutment fracture due to the loosening of the abutment screw. The fundamental cause of abduction of the abutment screw is caused by the slight movement due to the lowering of the retention force of the abutment screw. It is necessary to minimize loosening of the abutment screw to avoid problems such as fracture during the period of using the implant. The purpose of this study is to investigate the structure of the abutment screw to prevent the loosening of the abutment screw by forming 0.5mm slot.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.158-162
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• 2005

The objective of this study was to assess the assimilable organic carbon (AOC) in processing water, a measurement of biostability, at several stages of a full-scale nanofiltration (NF) water treatment plant. The NF membrane plant investigated was a $45,400\;m^3$/day (12 mgd) water softening facility at Plantation City in southern Florida, which utilized an organic rich groundwater (dissolved organic carbon (DOC) = 17.6 mg/L) originated from a surficial aquifer. The average AOC concentration of raw feed water was estimated at 158 g/L acetate-C. After pretreatment(acid and antiscalant addition), AOC levels increased by 12.7%, suggesting that pretreatment chemicals used to control scaling may deteriorate feed water biostability. The results also demonstrated that nanofiltration was capable of effectively removing 63.4% of AOC and 94.8% of DOC from the raw water. AOC rejection in stage 1 (${\approx}\;68%$) was slightly higher than that of stage 2 (${\approx}\;58%$) indicating that AOC was removed less at the solution environment (i.e. low pH, high ionic strength and high hardness), which was often created in the $2^{nd}$ stage of full-scale membrane plants due to pretreatment (acid addition) and high recovery operation.

• Journal of Environmental Health Sciences
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• v.32 no.6
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• pp.539-542
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• 2006

The objective of this paper is to compare the applicability of assimilable organic carbon (AOC) or biodegradable dissolved organic carbon (BDOC) for quantifying biodegradable organic material (BOM) and bio-stability in distribution systems for a variety of finished waters. The study the data is derived from was part of an AWWARF and Tampa Bay Water tailored collaboration project to determine the effect of blending different waters on distribution system water quality. Seven different finished waters were produced from surface, ground, or brackish water on site and fed 18 independent pilot distribution systems (PDSs), either as single finished water or as a blend of several finished waters. AOC and BDOC have often been used as indicators of bacterial regrowth potential in distribution systems. In this study, AOC was the more useful assay of the two for the BOM concentrations observed in the PDSs. BDOC did not distinguish BOM while AOC did at the low BOM levels from many of the advanced treatments (e.g. RO, $O^3/BAC$). AOC in contrast allowed much more meaningful calculations of the consumption or production of AOC as the blends passed through the PDSs even for very low BOM blends. In addition, meaningful trends corresponding to changes in heterophic plate count (HPC) were observed for AOC but not for BDOC. Moreover, AOC stability was associated with waters produced from advanced membrane treatment.

• Korean Journal of Materials Research
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• v.20 no.3
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• pp.132-136
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• 2010

This study examined the biostability and drug delivery efficiency of g-$Fe_2O_3$ magnetic nanoparticles (GMNs) by cytotoxicity tests using various tumor cell lines and normal cell lines. The GMNs, approximately 20 nm in diameter, were prepared using a chemical coprecipitation technique, and coated with two surfactants to obtain a water-based product. The particle size of the GMNs loaded on hangamdan drugs (HGMNs) measured 20-50 nm in diameter. The characteristics of the particles were examined by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-TEM) and Raman spectrometer. The Raman spectrum of the GMNs showed three broad bands at 274, 612 and $771\;cm^1$. A 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay showed that the GMNs were non-toxic against human brain cancer cells (SH-SY5Y, T98), human cervical cancer cells (Hela, Siha), human liver cancer cells (HepG2), breast cancer cells (MCF-7), colon cancer cells (CaCO2), human neural stem cells (F3), adult mencenchymal stem cells (B10), human kidney stem cells (HEK293 cell), human prostate cancer (Du 145, PC3) and normal human fibroblasts (HS 68) tested. However, HGMNs were cytotoxic at 69.99% against the DU145 prostate cancer cell, and at 34.37% in the Hela cell. These results indicate that the GMNs were biostable and the HGMNs served as effective drug delivery vehicles.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.05
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• pp.105-107
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• 1992

• Journal of Biomedical Engineering Research
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• v.39 no.3
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• pp.140-145
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• 2018

Cancer is a major burden of human disease worldwide. Current chemotherapy has severe side effects because the drugs affect whole body nonspecifically. In addition, the drugs to reach cancer cells are very limited. Over the last two decades, Drug Delivery System (DDS) using nanoparticles has suggested promising results to improve current limitations. In this study, we prepared PLGA nanoparticles with different charge properties and observed their stability and internalization effect to cancer cells. Results using Dynamic Light Scattering (DLS) and Fourier Transform Infrared Spectroscopy (FTIR) confirmed the size and chemical composition of the nanoparticles. The stability of the nanoparticles in pH buffers were variable depending on charge properties. The nanoparticles showed different cytotoxicity and internalization effects to MCF-7 human breast cancer cells. In conclusion, we demonstrated the importance of delicately engineered nanoparticles for better DDS in cancer.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.39-42
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• 1997

Biostabilities of the iron oxide MRI contrast agent were evaluated using the cytotoxicity test and the animal test. Six experimental groups (35, 17, 5, 3.4, 1.7, 0.9 mg of iron oxide/10ml) and a control group were prepared for the cytotoxicity test. The cell count of higher concentration than 5 mg/10m1 become decrease significantly after 4-days incubation. Iron oxide was injected into the right vein of the two fully grown rabbits with the concentration of 0.5 or 0.9mg/kg of body weight respectively. Blood samples were collected and analyzed in turn after 30min, 1, 2, 4, 8, 16, 30, 60, 90days injection. The body temperature and weight of rabbits were measured simultaneously. The result of blood and serum analyses and the body temperature shows that there was no significant variation with respect to the sampling term and the dosage within this experimental conditions.

• Journal of Industrial Technology
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• v.43 no.1
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• pp.25-31
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• 2023

Stretchable and flexible electronics that comply with dynamic movements and micromotion of the human tissues can enable real-time monitoring of physiologic signals onto the human skin and in the brain, respectively. Especially, gallium based liquid metal stretchable electronics can offer human-interactive biosensors to monitor various physiologic parameters. However, the liquid-like nature, surface oxidation and contamination by organic materials, and low biostability of the liquid metals have still limited the long-term use as bioelectronics. Here we introduced electrochemical deposition without oxidation pathways to overcome these practical challenges in liquid metal bioelectronics. CNT/PDDA composite with reduction way and PEDOT:BF₄ with oxidation way under organic solvent are suggested as rationally designed material engineering approaches. We confirmed that the structures with the soft, flexible, and stretchable liquid metal platform can successfully detect dopamine with a high sensitivity and selectivity, record neural signals including action potentials without scar formation, and monitor physiologic signals such as EMG and ECG.