Hyon Hee Yoon

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Volatile fatty acids (VFAs) were produced from the marine macroalgae, Laminaria japonica, Pachymeniopsis elliptica, and Enteromorpha crinite by anaerobic fermentation using a microbial community derived from a municipal wastewater treatment plant. Methanogen inhibitor (iodoform), pH control, substrate concentration, and alkaline and thermal pretreatments(More)
Conversion of food wastes into lactic acid by simultaneous saccharification and fermentation (SSF) was investigated. The process involves saccharification of the starch component in food wastes by a commercial amylolytic enzyme preparation (a mixture of amyloglucosidase, alpha-amylase, and protease) and fermentation by Lactobacillus delbrueckii. The highest(More)
TiO2 films were prepared on glass substrates using the sol-gel process for a dye-sensitized solar cell application. The TiO2 sol was prepared using hydrolysis/polycondensation. Titanium (IV) Tetra Isopropoxide (TTIP) was used as precursor and Nitric acid (HNO3) was used as a catalyst for the peptization. The crystal structure and morphology of the prepared(More)
In this study, a novel method was proposed for the biological pretreatment of macroalgae (Laminaria japonica, Pachymeniopsis elliptica, and Enteromorpha crinita) for production of volatile fatty acid (VFA) by anaerobic fermentation. The amount of VFA produced from 40 g/L of L. japonica increased from 8.3 g/L (control) to 15.6 g/L when it was biologically(More)
Properties of ferritin, immobilized on dithiobis (N-succinimydyl propionate) (DTSP)-covered gold electrode, in 3-morpholino propanesulfonic acid buffer were investigated by AFM and FE-SEM. Electrochemical properties the ferritin was measured by a cyclic volatammetry. When the potentials of 0.2, 0.34, and 1.0V vs. Ag/AgCl were applied for 15h for the(More)
Ferritin is a globular protein consisting of 24 subunits to form a hollow shell and is capable of storing iron in the cavity. Findings that the naturally existing iron core of ferritin can be readily extracted and replaced with a variety of electroactive materials make ferritin suitable for biosensor and biofuel cell applications. The immobilization of(More)
A strain of Clostridium thermoaceticum (ATCC 49707) was evaluated for its homoacetate potential. This thermophilic anaerobe best produces acetate from glucose at pH 6.0 and 59 degrees C with a yield of 83% of theoretical. Enzyme hydrolysis of two substrates, a-cellulose and a pulp mill sludge, yielded 68% and 70% digestion, respectively. The optimum(More)
A NiCo2O4 bimetallic electro-catalyst was synthesized on three-dimensional graphene (3D graphene) for the non-enzymatic detection of urea. The structural and morphological properties of the NiCo2O4/3D graphene nanocomposite were characterized by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. The NiCo2O4/3D graphene was deposited on(More)
An electrochemical biosensor based on sulfonated graphene/polyaniline nanocomposite was developed for urea analysis. Oxidative polymerization of aniline in the presence of sulfonated graphene oxide was carried out by electrochemical methods in an aqueous environment. The structural properties of the nanocomposite were characterized by Fourier-transform(More)