Publications by authors named "Sangjoon Hahn"

Randomization among successive choices is important in adaptive decision-making, particularly for strategic interactions in which the optimal strategy is a mixed strategy. Patients with schizophrenia have been reported to have deficits in random sequential behaviors arising from impaired executive function. However, whether schizophrenic patients exhibit distinct behaviors for response randomization in one- and two-person games requiring different behavioral strategies is not known.

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We present a method for glucose prediction from mid-IR spectra by independent component analysis (ICA). This method is able to identify pure, or individual, absorption spectra of constituent components from the mixture spectra without a priori knowledge of the mixture. This method was tested with a two-component system consisting of an aqueous solution of both glucose and sucrose, which exhibit distinct but closely overlapped spectra.

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Glucose determination based on near-IR spectroscopy is investigated for reflectance and transmittance measurement. A wavelength range is 1100 to 2500 nm, which includes both the combination and overtone bands of glucose absorption. Intralipid solutions are used as samples, where glucose concentrations vary between 0 and 1000 mg/dl.

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An ethyl acetate extract of Oryza sativa (rice) hulls yielded seven compounds: hentriacontane, 1-tetratriacontanol, beta-sitosterol, momilactone A, momilactone B, tricin (a flavonoid), and beta-sitosterol-3-O-beta-D-glucoside. The structures of these compounds were elucidated with 500 MHz nuclear magnetic resonance (NMR), using 1D and 2D spectral methods, aided by electron ionization mass spectrometry (EI-MS), fast atom bombardment mass spectrometry (FAB-MS), infrared (IR), and ultraviolet (UV) spectrophotometry. The complete 1H NMR assignments for momilactone A and B and 13C NMR assignments for tricin are discussed.

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We have determined the glucose concentration of whole blood from mid-infrared spectra without sample preparation or use of chemical reagents. We selected 1119-1022 cm(-1) as the optimal wavelength range for our measurement by making a first-loading vector analysis based on partial least-squares regression. We examined the influence of hemoglobin on samples by using different calibration and prediction sets.

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