• Journal of the Korean Electrochemical Society
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• v.10 no.1
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• pp.43-47
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• 2007

Electrochemical rectification at electrode chemically modified with redox active agents isolated at monolayer level was considered. Formulation of the rising part of linear sweep voltammogram at steady and rotating disc electrode was introduced.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.877-878
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• 2006

The sintered parts are mainly used for automobile industry, and a part of air conditioners. In automobile industry, the application range of sintered parts is very broad and use for a driving and a lubricating system. And air conditioner uses them for compressor. Grinding of compressor and pump parts is very difficult these days, because these parts use High hardness materials and require high precision grinding. Tool life has to be extended to decrease production cost. We analyzed processing mechanism and developed new grinding wheels for Double Disk Grinding. And, we introduce new truing technology that improved tool-life and precision.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.798-800
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• 2003

Recently, in optical storage device technical trends, the size of optical drive is slimmer to adopt notebook computer and the power of actuator is higher to achieve the high transfer rate. However, these trends of optical disc drives tend to increase the temperature of the actuator part, it causes some problems on the performance of optical parts - the resonance frequency of the actuator is down to lower band and the objective lens, coil and magnet are easily damaged. In this study, to overcome these thermal problems, the numerical simulations of heat transfer were performed. As the result of simulations, the thermal characteristic of the hybrid actuator is better than the previous design. And, it shows the good dynamic performance in experiment.

• Communications of the Korean Mathematical Society
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• v.37 no.4
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• pp.1025-1039
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• 2022

For given non-negative real numbers 𝛼_k with ∑^m_k=1 𝛼_k = 1 and normalized analytic functions f_k, k = 1, …, m, defined on the open unit disc, let the functions F and Fn be defined by F(z) := ∑^m_k=1 𝛼_kf_k(z), and F_n(z) := n^-1 ∑^n-1_j=0 e^-2j𝜋i/nF(e^2j𝜋i/nz). This paper studies the functions f_k satisfying the subordination zf'_k(z)/F_n(z) ≺ h(z), where the function h is a convex univalent function with positive real part. We also consider the analogues of the classes of starlike functions with respect to symmetric, conjugate, and symmetric conjugate points. Inclusion and convolution results are proved for these and related classes. Our classes generalize several well-known classes and the connections with the previous works are indicated.

• Microbiology and Biotechnology Letters
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• v.9 no.4
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• pp.207-212
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• 1981

A strain of Penicillium sp. which produces considerable amount of $\beta$-galactosidase was selected from extracellular $\beta$-galactosidase-producing fungi isolated from soil. The enzyme was found to be very stable in neutral pH range. Maximum enzymatic activity was reached after 72 hr of incubation in a wheat bran medium at 3$0^{\circ}C$. Productivity of the enzyme appeared not to be affected by the addition of carbon sources to the medium but the activity of the enzyme was increased from 14% to 85% by the addition of various nitrogen sources. The enzyme extracted from the wheat-bran culture of the Penicillium sp. was purified to 5050-fold by ammonium sulfate fractionation, SP-Sephadex C-50 chromatography, Ultrogel AcA 44 filtration and hydroxyapatite chromatography. The purified $\beta$-galactosidase was homogeneous on ultracentrifugation and disc electrophoresis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.187-190
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• 2009

A multiple pulse rocket motor distributes the thrust energy more effectively compared to typical rocket motor as providing subsequent thrusts by the pulse motors of the missile. The pulse rocket motor is the advanced technology to improve an end game capability of the missile by increasing the range and final velocity. A pulse separation device is the core part of the pulse motor. The pulse separation device of bulkhead type was designed and developed. The elastic-plastic structural analysis of the bulkhead and rupture disc was conducted. Several air tests were also conducted to confirm the structural safety and acceptability about the design concept. Test results were compared with the analysis results, which showed reasonable agreements.

• Journal of Digital Convergence
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• v.16 no.6
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• pp.353-361
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• 2018

RFW and RFE of castor fruit selected as part of the development of natural antimicrobials and antioxidants yielded 15.8% and 18.4% respectively. In the results of measuring the antimicrobial activity through paper disc method, the antimicrobial activity of castor fruits in ethanol extracts appeared. Especially, the activity was excellent in P. aeruginosa and S. aureus, and antimicrobial activity of C. was 1.5mm up to 16 hours. However, the proliferation of C. was observed again after 24 hours. In the MIC experiment results of RFE, S. aureus and P. aeruginosa showed 96% and 93% of antimicrobial activity, respectively. The DPPH radical scavenging activity of RLW and castor leaf ethanol extract showed $1.8{\pm}0.6%$ and $2.1{\pm}0.7%$ free radical scavenging activity at $1000({\mu}g/m{\ell})$. This study is expected to provide basic data for the development of antimicrobial agents and antioxidants using natural products.

• Korean Journal of Food Science and Technology
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• v.8 no.3
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• pp.141-146
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• 1976

1) The purified enzyme was obtained with the specific activity 126.5 u/mg protein (about 45 times of the original activity) and the yield of 4.2%, by means of salting out with ammonium sulfate (0.5 saturation) of the crude enzyme solution, desalting by Sephadex G 25, CM cellulose columm chromatography, concentration by Sephadex G 25, and gel filtration by Sephadex G 75. 2) In the acrylamide gel disc electrophoresis of the purified enzyme, the main band and two obscure ones on the both side of the main band appeared, which indicated that the enzyme was considerably purified compared with its crude enzyme solution, even if it is not referred to as a pure protein.

• Food Science and Biotechnology
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• v.17 no.2
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• pp.313-318
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• 2008

This study was conducted to evaluate in vitro antioxidative and antimicrobial properties of ethanolic extracts from Allium victoriallis L. var. platyphyllum (AVP) with 6 different parts. The antioxidative activities of these samples were determined using the 4 separate methods that involved reducing power, DPPH, hydrogen radical scavenging, and lipid peroxidation with use of a $\beta$-carotene/linoleic acid system. The leaf part ethanolic extracts (1,000 ppm) showed the strongest inhibitory potential for reducing power, DPPH, and hydroxyl radicals to 99.8, 49.4, and 52.8%, respectively. Inhibition values of linoleic oxidation were calculated as 58.0, 39.5, and 38.0% for seed, flower, and leaf ethanolic extracts (1,000 ppm), respectively, from AVP. In addition, the ethanolic extracts of the root part showed the most effective antimicrobial activity. The inhibition zones of the root ethanolic extracts ($200\;{\mu}g/disc$) of AVP against Bacillus cereus and Staphylococcus aureus were 17 and 14 mm, respectively. In a micro-dilution assay, B. cereus, S. aureus, and Vibrio parahaemolyticus exhibited sensitivity to root part ethanolic extracts with an minimum inhibition concentration (MIC) value of 20, 28, and 18 mg/mL, respectively. Therefore, the AVP extracts may be suitable as antimicrobial and antioxidative agents in the food industry.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.2
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• pp.91-111
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• 2024

Most of utility cable tunnels are constructed utilizing shield TBM as part of the underground transmission line project. The TBM chamber is the only space inside the tunnel that encounters rock and soil, and is the place with the highest frequency of accident exposure, such as collapse and collision accidents. Since there is currently no way to measure the disc cutter wear from outside the chamber, frequent inspection by workers is essential. Accordingly, in this study, in order to prevent safety accidents inside the TBM chamber and expect the effect of shortening the construction period by reducing the number of chamber openings, the concept of disk cutter wear measurement technology was established and a prototype was produced. By considering prior technology and determining that magnetic sensors are most suitable for the excavation environment, wear measurement sensor package were developed integrating magnetic sensors, wireless communication modules, power supply, external casing, and monitoring systems. To verify the performance of the prototype in an actual excavation environment, a full-scale tunnelling test was performed using a 3.6 m EPB shield TBM. Based on the full-scale tests, five prototypes were operated normally among eight prototypes. It was analyzed that sensor measurement, wireless communication, and durability performance were secured within a maximum thrust of 3,000 kN and a rotation speed of 1.5 RPM.