• The Journal of Natural Sciences
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• v.8 no.1
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• pp.33-39
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• 1995

Klebsiella sp. L-10 was treated with physical and chemical mutagens, and one of the NTG mutant which increased hyaluronic acid complex yield 2.5 folds was selected. The yield of hyaluronic acid complex from Klebsiella sp. L-10 NTG 50 mutant reached maximum level I the YPD medium containing 0.1% yeast extract, 3% Bacto-tryptone, 3% dextrose, each 30mM of $K_2HPO_4$ and $KH_2PO_4$ (pH 6.0-6.5) with shaking culture at $37^{\circ}C$ for 24 hrs, and 2900mg of hyaluronic acid complex per litre of culture was produced under the above condition.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.4
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• pp.629-638
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• 2002

This paper deals with the free vibration analysis of compressive tapered members resting on elastic foundation using the Differential Quadrature Method. Based on the differential equation subjected to the boundary conditions, adopted from the open literature, which governs the free vibrations of such member, this equation is applied to the Differential Quadrature Method. For computing natural frequencies, the numerical procedures are developed by QR Algorithm, in which the Chebyshev-Gauss-Lobatto method is used for choosing the grid points. The numerical methods developed herein for computing natural frequencies are programmed in FORTRAN code, and all solutions obtained in this study are quite agreed with those in the open literature.

• Applied Biological Chemistry
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• v.39 no.6
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• pp.419-423
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• 1996

We have established the quantitative method for assay antimutagenic activity from natural products using SOS chromotest technique. Establishment of the method in this study makes it possible to numerize antimutagenic activities from samples in term of the sample amount required for 50% inhibition to mutagenic activity induced by the chemical mutagen under the standard assay condition. Antimutagenic activities of rices from different cultivars as well as other cereals were assayed through this method. The results revealed that antimutagenic activities of mutant cultivar, Suwon 393(Hyangdo) and Sanghaehyanghyulla(Jado), were higher than Chuchung which mainly consumed for steamed rice, and also indicated that antimutagenic activities of cereals, such as job'tear, buckwheat, small red bean, black bean were generally higher than that of brown rice.

• Microbiology and Biotechnology Letters
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• v.14 no.4
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• pp.271-277
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• 1986

A sisomicin-producing strain, Micromonospora inyoensis, was treated with various mutagens. The optimal death rates to obtain the high-producers of sisomicin were 90% for ultraviolet light, 99% for nitrosoguanidine, and 99.3% for nitrous acid, respectively. In place of the method of liquid culture, an agar plug method, which is easy and convenient, was used to measure the antibiotic-producing abilities of the strains isolated from mutagen-treated cells. On the other hand, as the selection method of overproducing mutants after mutagenesis, gradient agar plates which included various antibiotics and salts were used. Among the antibiotics and salts tested, gentamicin and kanamycin as antibiotics, and CuCl$_2$ and HgCl$_2$ as salts, were effective to select the high-producers of sisomicin.

• Journal of the Korea Society for Simulation
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• v.26 no.1
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• pp.39-46
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• 2017

An arrangement of passive sonars is considered to be a fixed underwater surveillance system for detecting an anti-submarine consistently. An effectiveness score for optimizing the arrangement of passive sonars is defined in a function of the probability of detection and localization. These two features contain various probabilistic variations including seasons, sea states, depths of water, etc. Due to this reason, the effectiveness scores show probabilistic characteristics from the input of the arrangement of passive sonars. This paper defines the optimization problem having the results of probabilistic characteristics from various parameters of input conditions. Also, we suggest a simulation-based process of deciding the optimized arrangement of passive sonars using DPSO(Discrete binary version of PSO) method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1993.10a
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• pp.163-168
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• 1993

현대 산업사회에서 발전소는 중요한 시설물이다. 특히 원자력발전소는 지진 과 같은 천재지변시 매우 위험하기 때문에 내진설계가 필수적으로 요구되어 진다. 최근 국내 원자력발전소의 증가와 1986년 이후 만들어진 내진관련 법 규에 따라 내진설계가 보편화 되어가고 있다. 본 연구에서는 발전소에서 쓰 이는 입축펌프를 해석대상기종으로하여 구조해석과 내진해석을 수행하엿다. 입축펌프는 큰 질량을 가진 모터가 펌프의 윗부분에 위치하고 있어 진동문 제가 야기되는 기종이다. 펌프의 고유진동수는 기초부의 강성과 수조의 내수 위에 따라 변하며, 펌프의 축계의 진동수에 비하여 구조계의 진동수가 운전 회전수에 가깝기 때문에 구조계의 진동이 문제시된다. 해석에 있어서 펌프는 단면이 변하는 Euler Beam으로 보고 유한요소법을 사용하여 모델링하였고, 물의 저항에 의한 부가질량을 고려하였다. 내진해석은 응답스펙트럼법으로 수행하였으며 GRS는 Housner가 0.2g에 대하여 제작한 것을 OBE 조건 (0.12g)으로 scaling하여 사용하였다. 각 모드에 대한 합성방법은 SRSS 법을 적용하였다. 또한 응답스펙트럼법과 시간이력해석의 결과를 비교하였으며, 시간이력해석에서, 수치해석방법으로는 Newmark법을 적용하였다. 지진자료 는, 1940년, California에서 발생한 Elcentro 지진 자료를 이용하였다. 연구수 행과정에서 기초강성계수와 수조내 물의 수위를 주된 인자로 하여 이들의 값에 따라 변하는 고유진동수를 고찰하고, 지진입력시 예상되는 최대응답을 구하여, 비교 분석하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.1
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• pp.60-67
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• 2022

A study was conducted to analyze the behavioral change of the kerosene flame ultrasonically-atomized under an ultrasonic standing-wave. Combustion region was visualized through DSLR, ICCD camera and the Schlieren photography with high-speed camera. The fuel consumption was measured by a precise scale. As a result, in the case of ultrasonic standing-wave excitation, it was observed that the intensity of OH radical(OH^*) was enhanced and optimal combustion condition was formed around the upper edge of the standing-wave field.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.533-538
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• 2006

This study deals with the static and dynamic stability analyses of simple tapered columns with constant volume. The crosssections of column taper are the regular polygons whose depths are varied with the parabolic functional fashion. The hingedhinged end constraint is chosen as the boundary condition of the column. The non-dimensional ordinary differential equation governing free vibrations of such column subjected to an axial load is derived and solved numerically. From numerical results, the relationships between natural frequencies and section ratios are obtained, from which the configurations of dynamic optimal shapes of columns and the strongest columns are extracted.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.181-186
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• 2005

This experiment was conducted to know the appropriate methods for extraction and determination of rutin contained buckwheat plants. The efficient HPLC analytical condition of rutin contained buckwheat plants was developed. The gradient elution employed a $250mm\times4.6mm$ i.d. Tosoh ODS 120T column. The gradient system was used two mobile phases. A gradient elution was performed with mobile phase A, consisting of $2\%$ Acetic $acid-45\%$ Acetonitrile, and mobile phase B, comprising $2\%$ aqueous acetic acid, and delivered at a flow rate of 1mL/min as follows: 0-18 min, $50-100\%$ A; 18-20 min, $100-50\%$ A; 20-22 min, $50\%$ A. The UV detection wavelength was set at 355 nm. The limit of detection (LOD) for rutin standard compound was 20 ng/mL. And, the higher content of rutin in the extracts was obtained by $80^{\circ}C$ reflex extraction for 120 min. from plants of buckwheat using ethanol.

• Geophysics and Geophysical Exploration
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• v.15 no.2
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• pp.57-65
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• 2012

Various numerical methods in simulation of seismic wave propagation have been developed. Recently an innovative numerical method called as the Spectral Element Method (SEM) has been developed and used in wave propagation in 3-D elastic media. The SEM that easily implements the free surface of topography combines the flexibility of a finite element method with the accuracy of a spectral method. It is generally used a weak formulation of the equation of motion which are solved on a mesh of hexahedral elements based on the Gauss-Lobatto-Legendre integration rule. Variational formulations of velocity-stress motion are newly modified in order to implement ADE-PML (Auxiliary Differential Equation of Perfectly Matched Layer) in wave propagation in 3-D elastic media, because a general weak formulation has a difficulty in adapting CFS (Complex Frequency Shifted) PML (Perfectly Matched Layer). SEM of Velocity-Stress motion having ADE-PML that is very efficient in absorbing waves reflected from finite boundary is verified with simulation of 1-D and 3-D wave propagation.