• Journal of Microbiology and Biotechnology
• /
• v.22 no.5
• /
• pp.628-636
• /
• 2012

Raw-starch-digesting enzyme (RSDA) was immobilized on Amberlite beads by conjugation of glutaraldehyde/polyglutaraldehyde (PG)-activated beads or by crosslinking. The effect of immobilization on enzyme stability and catalytic efficiency was evaluated. Immobilization conditions greatly influenced the immobilization efficiency. Optimum pH values shifted from pH 5 to 6 for spontaneous crosslinking and sequential crosslinking, to pH 6-8 for RSDA covalently attached on polyglutaraldehyde-activated Amberlite beads, and to pH 7 for RSDA on glutaraldehyde-activated Amberlite. RSDA on glutaraldehyde-activated Amberlite beads had no loss of activity after 2 h storage at pH 9; enzyme on PG-activated beads lost 9%, whereas soluble enzyme lost 65% of its initial activity. Soluble enzyme lost 50% initial activity after 3 h incubation at $60^{\circ}C$, whereas glutaraldehyde-activated derivative lost only 7.7% initial activity. RSDA derivatives retained over 90% activity after 10 batch reuse at $40^{\circ}C$. The apparent $K_m$ of the enzyme reduced from 0.35 mg/ml to 0.32 mg/ml for RSDA on glutaraldehyde-activated RSDA but increased to 0.42 mg/ml for the PG-activated RSDA derivative. Covalent immobilization on glutaraldehyde Amberlite beads was most stable and promises to address the instability and contamination issues that impede the industrial use of RSDAs. Moreover, the cheap, porous, and non-toxic nature of Amberlite, ease of immobilization, and high yield make it more interesting for the immobilization of this enzyme.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.4
• /
• pp.383-389
• /
• 2011

In this paper, a statistical calibration method is proposed in order to identify the variability of complex modulus for a rubber material due to operational temperature and experimental/model errors. To describe temperature- and frequency-dependent material properties, a fractional derivative model and a shift factor relationship are used. A likelihood function is defined as a product of the probability density functions where experimental values lie on the model. The variation of the fractional derivative model parameters is obtained by maximizing the likelihood function. Using the proposed method, the variability of a synthetic rubber material is estimated and applied to a rubber mount problem. The dynamic characteristics of the rubber mount are calculated using a finite element model of which material properties are sampled from Monte Carlo simulation. The calculated dynamic stiffnesses show very large variation.

• Journal of Magnetics
• /
• v.15 no.4
• /
• pp.209-212
• /
• 2010

Photoplethysmogram (PPG) and pressure pulse waveform (PPW) were compared and evaluated for the efficacy of stimulating knuckles by using the pulsed magnetic field. Both signals were observed simultaneously while the knuckles were exposed for 10 min to the pulsed magnetic field, with maximum field intensity of 0.8 T and transition time of 0.126 msec. After 5 min stimulation of the knuckles, the results showed that the aging indexes calculated from the second derivative of the PPG were increased from -1.913 to 0.072, and that of the PPW from -0.063 to 0.387. However, for the relatively long-term stimulation for 10 min, we found that the values of both the aging indexes of the second derivatives and augmentation index of the PPW returned to the starting level. The changes observed in characteristic factors such as the aging indexes of the second derivatives and augmentation index of the PPW indicate the potential of pulsed magnetic field stimulation as a therapeutic method for the treatment of patients with peripheral vascular disease.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.41 no.4
• /
• pp.181-189
• /
• 2015

Objectives: The purpose of this study was to compare the microbial and clinical effects of mechanical debridement (MD) alone or in combination with the application of enamel matrix derivative (EMD) and sustained-release micro-spherical minocycline (MSM) for treatment of peri-implant mucosal inflammation (PIMI). Materials and Methods: Subjects with at least one implant with PIMI were included and divided into control and two different test groups. In all three groups, MD was performed. In the MSM group, following MD, MSM was placed subgingivally around the implants. In the EMD group, after MD, EMD was placed in the sulcus around the implants. Sampling of peri-implant crevicular fluid for microbial analysis with real-time polymerase chain reaction and recording of probing depth (PD) and bleeding on probing (BOP) were performed prior to as well as two weeks and three months after treatment. Median values and interquartile range were estimated for each variable during the various assessment intervals of the study. Results: In all groups, at two weeks and three months, the counts of Porphyromonas gingivalis decreased significantly compared to baseline. Levels of P. gingivalis were significantly reduced in MSM (P<0.001) and EMD (P=0.026) groups compared to the control group. Also, clinical parameters improved significantly at two weeks and three months. Reduction of PD was significant in MSM (P<0.001) and EMD (P<0.001) groups. The decrease in BOP in the MSM, EMD, and control groups was 60%, 50%, and 20%, respectively. Conclusion: The use of MSM and EMD can be an adjunctive treatment for management of PIMI and improves clinical parameters and reduces P. gingivalis burden three months after treatment.

• Korean Journal of Microbiology
• /
• v.54 no.1
• /
• pp.18-23
• /
• 2018

A new naturally occurring benzoic acid derivative, benzyl 2,4-di(benzyloxy)benzoate (1) and six known compounds (2-7) were isolated from the fungus, Preussia sp. found in frozen soil of the Himalaya Mountain. The structures of the new compound, together with the known compounds were determined by 1D-and 2D-NMR experiments, as well as comparison with published values. In addition, to the best of our knowledge, the known compounds 2-7 were isolated for the first time from the genus Preussia and the family Sporormiaceae. The isolates were evaluated for cancer chemopreventive potential based on their ability to inhibit nitric oxide (NO) production induced by lipopolysaccharide (LPS) in mouse macrophage RAW 264.7 cells in vitro. Compounds 1 and 2 inhibited NO production by 50.7% and 88.5% at a concentration of 100 mg/ml, respectively.

• Communications for Statistical Applications and Methods
• /
• v.29 no.1
• /
• pp.85-101
• /
• 2022

Derivative-linked securities (DLS) is a type of derivatives that offer an agreed return when the underlying asset price moves within a specified range by the maturity date. The underlying assets of DLS are diverse such as interest rates, exchange rates, crude oil, or gold. A German 10-year bond rate-linked DLS and a USD-GBP CMS rate-linked DLS have recently become a social issue in Korea due to a huge loss to investors. In this regard, this paper accounts for the payoff structure of these products and evaluates their prices and fair coupon rates as well as risk measures such as Value-at-Risk (VaR) and Tail-Value-at-Risk (TVaR). We would like to examine how risky these products were and whether or not their coupon rates were appropriate. We use Hull-White Model as the stochastic model for the underlying assets and Monte Carlo (MC) methods to obtain numerical results. The no-arbitrage prices of the German 10-year bond rate-linked DLS and the USD-GBP CMS rate-linked DLS at the center of the social issue turned out to be 0.9662% and 0.9355% of the original investment, respectively. Considering that Korea government bond rate for 2018 is about 2%, these values are quite low. The fair coupon rates that make the prices of DLS equal to the original investment are computed as 4.76% for the German 10-year bond rate-linked DLS and 7% for the USD-GBP CMS rate-linked DLS. Their actual coupon rates were 1.4% and 3.5%. The 95% VaR and TVaR of the loss for German 10-year bond rate-linked DLS are 37.30% and 64.45%, and those of the loss for USD-GBP CMS rate-linked DLS are 73.98% and 87.43% of the initial investment. Summing up the numerical results obtained, we could see that the DLS products of our interest were indeed quite unfavorable to individual investors.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
• /
• 2001.06a
• /
• pp.1041-1041
• /
• 2001

Removal of variability in spectra data before the application of chemometric modeling will generally result in simpler (and presumably more robust) models. Particularly for sparsely sampled data, such as typically encountered in diode array instruments, the use of Savitzky-Golay (S-G) derivatives offers an effective method to remove effects of shifting baselines and sloping or curving apparent baselines often observed with scattering samples. The application of these convolution functions is equivalent to fitting a selected polynomial to a number of points in the spectrum, usually 5 to 25 points. The value of the polynomial evaluated at its mid-point, or its derivative, is taken as the (smoothed) spectrum or its derivative at the mid-point of the wavelength window. The process is continued for successive windows along the spectrum. The original paper, published in 1964 [1] presented these convolution functions as integers to be used as multipliers for the spectral values at equal intervals in the window, with a normalization integer to divide the sum of the products, to determine the result for each point. Steinier et al. [2] published corrections to errors in the original presentation [1], and a vector formulation for obtaining the coefficients. The actual selection of the degree of polynomial and number of points in the window determines whether closely situated bands and shoulders are resolved in the derivatives. Furthermore, the actual noise reduction in the derivatives may be estimated from the square root of the sums of the coefficients, divided by the NORM value. A simple technique to evaluate the actual convolution factors employed in the calculation by the software will be presented. It has been found that some software packages do not properly account for the sampling interval of the spectral data (Equation Ⅶ in [1]). While this is not a problem in the construction and implementation of chemometric models, it may be noticed in comparing models at differing spectral resolutions. Also, the effects on parameters of PLS models of choosing various polynomials and numbers of points in the window will be presented.

• Parasites, Hosts and Diseases
• /
• v.60 no.6
• /
• pp.401-407
• /
• 2022

Antimalarial drugs play an important role in the control and treatment of malaria, a deadly disease caused by the protozoan parasite Plasmodium spp. The development of novel antimalarial agents effective against drug-resistant malarial parasites is urgently needed. The novel derivatives, SKM13-MeO and SKM13-F, were designed based on an SKM13 template by replacing the phenyl group with electron-donating (-OMe) or electron-withdrawing groups (-F), respectively, to reverse the electron density. A colorimetric assay was used to quantify cytotoxicity, and in vitro inhibition assays were performed on 3 different blood stages (ring, trophozoite, and schizonts) of P. falciparum 3D7 and the ring/mixed stage of D6 strain after synchronization. The in vitro cytotoxicity analysis showed that 2 new SKM13 derivatives reduced the cytotoxicity of the SKM13 template. SKM13 maintained the IC₅₀ at the ring and trophozoite stages but not at the schizont stage. The IC₅₀ values for both the trophozoite stage of P. falciparum 3D7 and ring/mixed stages of D6 demonstrated that 2 SKM13 derivatives had decreased antimalarial efficacy, particularly for the SKM13-F derivative. SKM13 may be comparably effective in ring and trophozoite, and electron-donating groups (-OMe) may be better maintain the antimalarial activity than electron-withdrawing groups (-F) in SKM13 modification.

• Journal of the Korean Chemical Society
• /
• v.55 no.5
• /
• pp.756-759
• /
• 2011

In this paper, chloracetyl chitosan (CACTS) was prepared at first. In the molecules of CACTS, there are active chlorine groups, which can take part in other reactions. Thus, number of chitosan derivatives will be obtained after chlorine is substituted. Choosing pyridine as the active group, a novel water-soluble chitosan derivative, (2-pyridyl)-acetyl chitosan (PACTS) was obtained and its antioxidant activity against hydroxyl radicals and superoxide radicals was assessed. The results indicated that PACTS had better antioxidant activity than that of chitosan, carboxymethyl chitosan (CMCTS), hydroxypropyl chitosan (HPCTS), and Vitamin C. And the $IC_{50}$ values against hydroxyl radicals and superoxide radicals were 0.31 mg/mL and 0.21 mg/mL, respectively.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.22 no.1
• /
• pp.60-66
• /
• 2017

This paper presents the design of a proportional-integral (PI)-proportional-derivative (PD) position controller without using a speed controller in motor drive systems. Unlike the existing PI-PD position controller design methods, the proposed controller is designed by reducing the entire position control system to a second-order transfer function. Thus, the gain values for the PI-PD position controller can be determined easily by a given bandwidth of the position controller. The PI-PD position controller designed by the proposed method is adopted for position control in an interior permanent magnet synchronous motor drive system to confirm the validity of the proposed design method. The effectiveness of the proposed design method is confirmed through experiments.