Seong-Yeop Jeong

Generating Characteristics of a Cantilever-Type Unimorph Piezoelectric Generator Depending on the Material and Mass

Structure of a cantilever-type unimorph piezoelectric generator was proposed and designed so as to allow the generator to resonate at frequencies lower than commercial frequencies. This generator is capable of generating amount of voltage its despite low frequency and simple fabrication that result from its simple structure. In this paper, the resonance characteristics of the generator depending on significant parameters were determined through a modal analysis and the influence of each parameter was analyzed to define each its level of sensitivity on the high output characteristics using ANSYS, a FEM program. The generators resonated at frequencies lower than 60 [Hz], as determined through the FEM results. The generating characteristics were then defined by implementing vibration experiment and comparing the results with those from the analysis. The resonance frequency and output power depending on changes in the mass and material were determined by the analysis.

Optimization of Production Yield for Neohesperidin by Response Surface Methodology

Neohesperidin is a natural new nutrition sweetener, widely existing in plants of dry citrus peel, which can be derived from extraction. Since the sweetness is 1,300-1,500 times greater than that of sugar, neohesperidin are widely used in fruit juices, wines, beverages, bakeries and pharmaceutical formulations, and are particularly suitable for consumption by diabetic patients. However, the yield of extraction from citrus peel waste is very low. In this study optimal yield conditions were determinedusing response surface methodology (RSM) in order to increase the neohesperidin extraction yield. The critical factors for maximum extraction yield were selected extraction pressure (), extraction time (), and concentration of ethanol (). As a result, the extraction yield was improved when the extracting pressure increased. The extraction yield also increased in a time-dependent manner. When adding ethanol as an assistance solvent to the supercritical carbon dioxide, extraction yield was increased as more ethanol concentration was added. Finally, the extraction yield of neohesperidin was improved to about 162.22% compared to ethanol extraction as a conventional method.

Activity assay for nisin-like acidic bacteriocins using an optimal pH-conditioned gel matrix.

A new zymography for detecting nisin-like acidic bacteriocins was developed using a tricine-sodium dodecyl sulfate (SDS) gel and an acidic gel matrix (pH 4.0). After electrophoresis, proteins in the tricine gel were electrotransferred to an optimal pH-conditioned gel matrix (OP-CGM). The OP-CGM was overlaid with indicator cells (Bacillus cereus) embedded in nutrient broth soft agar (0.8%, w/v). Antibacterial activity shown as a growth inhibition using B. cereus was detected at approximately 3.8kDa. Because nisin is unstable in buffers at pH values over 6.0, the common electrophoretic systems, SDS-polyacrylamide gel electrophoresis and tricine gel, are not suitable for detection of nisin-like acidic bacteriocins.

Design of a Nib-Shaped Ultrasonic Motor for Auto-focusing Camera

In this paper, a newly designed nib-shaped ultrasonic motor was proposed. The motor can be easily designed and fabricated as a small actuator due to its simple structure composed of a nib-shaped elastic body frame and two ceramics. Also, the motor is expected to be used as small actuator for auto-focusing camera by designing the size of the motor less than 10[mm], because the ultrasonic motor has general merit of generating high torque in spite of low speed. When two sinusoidal sources with phase difference of 90 degrees are applied to two ceramics, the elliptical displacement is generated at contact tip of the motor. To define vibration shapes and output characteristics of the motor, design parameters were chosen and the modeling of the motor was conducted by using ANSYS 11.0, FEM(Finite Element Method) Program. Elliptical motions of the contact tips of the stator were consistently obtained at resonance frequency. Characteristics of the motor such as frequency, speed, torque, and pre-load were measured by using the driving system and measurement equipment. From the fabricated prototype motor, high rotational speeds were obtained by applying relatively low voltages. Speed and torque were increased linearly by increasing the voltage

Characterization of Lactobacillus brevis SCML 432 isolated from Meju in Sunchang and optimization of its culture conditions by statistical methods

When used as a starter in the manufacture of Meju, it is expected that the quality of the soup products can be improved. In this study, we isolated Lactobacillus strain having possible safety and food-industrial benefits as a starter. Four hundred and seven isolates were screened from Meju, and chemically characterized for their antibacterial activity against Bacillus cereus, non-productivity of biogenic amine, and hemolysis. Eight of the isolates were selected upon chemical characterization, and their antioxidant and β-glucosidase activity was measured. Finally, we selected, and measured its enzyme activity and antibiotic resistance. Next, we investigated its cell growth, showed maximum biomass of 3.5 g/L after 28 h of culture. The ingredients of the medium to improve biomass were selected using the Plackett-Burman design (PBD) and central composite design (CCD). The results obtained using PBD revealed molasses, yeast extract, and maltose to be significant factors determining the biomass of the L. brevis SCML 432 strain. The CCD was then applied with three variables found from PBD and the optimum values were predicted to be 5.5% molasses, 1.5% yeast extract, and 2.0% maltose, and the maximum biomass was predicted to be 11.2 g/L. Through model verification, we confirmed that the predicted and actual results were similar, with about 3.2-fold improvement in the biomass from 3.5 g/L to 11.3 g/L when compared to that obtained in basal medium. These results suggest that SCML 432 has high potential in the food industry as a starter.

Screening of Non-Biogenic-Amine-Producing Bacillus subtilis and Medium Optimization for Improving Biomass by the Response Surface Methodology

Biogenic amines are produced primarily by microorganisms found in fermented foods and are often implicated in poisoning incidents in humans. In this study, 620 strains of microorganisms were isolated from traditional Korean fermented food in Sunchang in order to screen for non-biogenicamine- producing microorganisms present in these foods. One strain was identified and named Bacillus subtilis SCJ1, by using 16S rRNA sequencing and biochemical characterization. We investigated the cell growth of this organism in order to understand its potential for industrial application. To this end, we optimized the culture medium constituents by using the response surface methodology. The Plackett-Burman experimental design was used for screening of the medium constituents, such as molasses, yeast extract and peptone, for improving cell growth. In order to determine the optimal concentration of each constituent, we used a central composite design. Consequently, the optimized concentrations of molasses, yeast extract and peptone were predicted to be 27.5 g/l, 7.5 g/l and 17.5 g/l, respectively. By model verification, we confirmed that a 1.49-fold increase in dry cell weight compared to the basal medium-from 1.32 g/l, to 1.9722 g/l-was achieved.

Optimization of a Medium for the Production of Cellulase by Bacillus subtilis NC1 Using Response Surface Methodology

Hee-Jong Yang 1 , Chang-Su Park 2 , Ho-Yeon Yang 3 , Su-Ji Jeong 1 , Seong-Yeop Jeong 1 , Do-Youn Jeong 1 , Dae-Ook Kang, Ja-Young Moon and Nack-Shick Choi* Microbial Institute for Fermentation Industry (MIFI), Sunchang 595-804, Korea 2 Department of Food Science and Technology, Catholic University of Daegu, Hayang 712-702, Korea RealBioTech Co., Ltd., Gongju-si, Chungnam 314-853, Korea Department of Biochemistry and Health Science, Changwon National University, Changwon 641-773, Korea

Generating Characteristics of a Cross-Shaped Piezoelectric Energy Harvester

The cross shaped piezoelectric energy harvester is designed to generate effectively by given vibrations or forces at the center point of the harvester by consisting of four cantilever ceramic harvesters which are centro-symmetrically arranged in one structure. Moreover, these harvesters can be serially arranged on one shaft which going through the center points of each harvester. If vibration source is connected at one end of the shaft, the vibrations from the vibration source can be transferred to the center points of these harvesters simultaneously through the shaft and the harvesters can be activated by one vibration source. By FEA (finite element analysis) and experiment, generating voltage characteristics were obtained. Among the four kinds of materials of the metal plate, stainless steel (SUS304) was chosen to get the highest voltage. The output voltages were increased and the resonance frequencies were decreased when the elastic length was increased. Resonant frequencies and output voltages were not critically dependent on the elastic width from over a certain width. The output voltages and the resonance frequencies were increased when the elastic thickness was increased. By changing resistance of the external resistors, impedance matching was accomplished and higher voltage was obtained. Through the experiment of arrangement of harvesters on same shaft, possibility of multiplication of the generating power by increasing the number of harvesters was presented.

Speed and Torque Characteristics of Three-Phase Ultrasonic Motor

A three-phase ultrasonic motor was proposed as an actuator for small precision machinery. Twelve ceramic plates were attached on upper and bottom sides of the metal plate. When three-phase alternating voltage was applied to the stator, elliptical displacements were generated at the three inner edges of the stator. The displacement characteristics and resonance frequency were obtained by using a finite element analysis program. The maximum displacement was occurred at frequency of minimum impedance. The effectiveness of the proposed design was verified experimentally. By measuring characteristics of the motor such as speed and torque. When pre-load to rotor was increased, motor speed was decreased and torque of the motor was increased. Three contact points between the rotor and stator made stable driving of the motor.

Driving Characteristics of a Simple Square-Frame Ultrasonic Motor

A novel design of a simple square-frame USM (ultrasonic motor) was proposed. The stator of the motor consists of a square-frame shape elastic body and four rectangular plate ceramics. The four ceramics were attached to outer surfaces of the square-frame elastic body. The same phase voltages were applied to the ceramics on horizontal surfaces, and 90 degree phase difference voltages were applied to the ceramics on vertical surfaces. When the four outer edges of stator were clamped, the bending vibrations of the right angled bars were transformed into travelling vibrations and elliptical displacements were generated at the center of the bars. To find an optimal size of a stator, that generates elliptical displacement at the centers of the inner surfaces, the finite element analysis program ATILA was used. The analyzed results were compared to the experimental results. As result, the model EL10W3T0.5_CL7 which generates the maximum elliptical displacement was chosen by analyzing the resonance mode according to changes in frequency.