• Microbiology and Biotechnology Letters
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• v.17 no.3
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• pp.193-197
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• 1989

The three new Alkylene bisdithionreido $\beta$-lactam derivatives were synthesized and evaluated for antimicrobial activities. Treatment of cefadroxil.2DMF with alkylene diisothiocyanate which was obtained by the reaction of alkylene diamine with carbon disulfide, sodium hydroxide and ethyl chloroformate afforden alkylene bisdithioureido $\beta$ -lactam derivatiives. The antimicrobial activities of the compounds synthesized were ethylene bisdithioureido $\beta$-lactam derivative lost the sensitivity against Escherichia coli but showed potent antimicrobial activity against $\beta$-lactams Escherichia coli, but, tetramethylene bisdithioureido $\beta$-lactam derivative and hexamethylene bisdithioureido $\beta$ -lactam derivative compounds showed diminished or no antimicrobial activities.

• Korean Journal of Food Science and Technology
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• v.4 no.2
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• pp.72-76
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• 1972

Seven new hydroxyamine derivatives of 2,2'-methylene bis(3,4,6-trichloroacetoxy benzene) were synthesized by the Mannich reactions. 13 strains of microorganisms were tested for sensitivity to these derivatives by both paper disk method and tube dilution method. Of these compounds, -NHOH compound displays the most effective antimicrobial activity in vitro against Brevibacterium ammoniagenes, Staphylococcus aureus and Bacillus subtilis. Its minimal inhibitory concentration is $1.6{\mu}g/ml$ for Brevibacterium ammoniagenes, and $5{\mu}g/ml$ for Staphylococcus aureus and Bacillus subtilis.

• Analytical Science and Technology
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• v.6 no.1
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• pp.77-82
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• 1993

Negative chemical ionization mass spectrometry(NCI-MS) can provide the enhancement in sensitivity in the analysis of amino acids. For molecules which are strongly electron-capturing, NCI-MS has been of amino to have detection limits in the femtomole to attomole($10^{18}$) range. Because of the selectivity of the ionization process, background noise is diminished, further enhancing signal to noise ratio. In this paper, we explored a dinitro-phenyl derivatives of amino acids by NCI-MS and compared it with eletron ionization method. The results demonstrated NCI-MS produces very clean spectra with a very little noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1038-1043
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• 2003

There are many industrial applications including thin-body structures such as fins. For the numerical modeling of radiation of sound from thin bodies, the conventional boundary element method (BEM) using the Helmholtz integral equation fails to yield a reliable solution. Therefore, many researchers have tried to solve the thin-body acoustic problems. In the area of the design sensitivity analysis (DSA) and optimization methods, however, there has been just a few study reported. Especially fur the thin-body acoustics, however, no further study in the DSA and optimization fields has been reported. In this research, the normal derivative integral equation is adopted as an analysis formulation in the thin-body acoustics, and then used for the sizing DSA and optimization. Since the gradient-based method is used for the optimization, it is important to have accurate gradients (design sensitivities) of the objective function and constraints with respect to the design variables. The DSA formulations are derived through chain-ruled derivatives using the finite element method (FEM) and BEM by using the direct differentiation and continuum variation concepts. The proposed approaches are implemented and validated using a numerical example.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.8
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• pp.398-402
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• 2002

The ELD computation has been based upon the so-called B-coefficient which uses a quadratic approximation of system loss as a function of generation output. Direct derivation of system loss sensitivity based on the Jacobian-based method was developed in early 1970s', which could eliminate the dependence upon the approximate loss formula. However, both the B-coefficient and the Jacobian-based method require a complicated Procedure for calculating the system loss sensitivity included in the constraints of the optimization problem. In this paper, an ELD formulation in which only the bus power equations are defined as the constraints has been introduced. Derivation of the partial derivatives of the system loss with respect to the generator output and calculation of the penalty factors for individual generators are not required anymore in proposed method. A comprehensive solution procedure including calculation of the Jacobians and Hessians of the formulation has been presented in detail. Proposed ELD formulation has been tested on a sample system and the simulation indicated a satisfactory result.

• Journal of Ecology and Environment
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• v.31 no.3
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• pp.233-241
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• 2008

Functional feeding groups (FFGs) of benthic macroinvertebrates are guilds of invertebrate taxa that obtain food in similar ways, regardless of their taxonomic affinities. They can represent a heterogeneous assemblage of benthic fauna and may indicate disturbances of their habitats. The proportion of different groups can change in response to disturbances that affect the food base of the system, thereby offering a means of assessing disruption of ecosystem functioning. In this study, we used benthic macroinvertebrate communities collected at 650 sites of 23 different water types in the province of Overijssel, The Netherlands. Physical and chemical environmental factors were measured at each sampling site. Each taxon was assigned to its corresponding FFG based on its food resources. A multilayer perceptron (MLP) using a backpropagation algorithm, a supervised artificial neural network, was applied to evaluate the influence of environmental variables to the FFGs of benthic macroinvertebrates through a sensitivity analysis. In the evaluation of input variables, the sensitivity analysis with partial derivatives demonstrates the relative importance of influential environmental variables on the FFG, showing that different variables influence the FFG in various ways. Collector-filterers and shredders were mainly influenced by $Ca^{2+}$ and width of the streams, and scrapers were influenced mostly with $Ca^{2+}$ and depth, and predators were by depth and pH. $Ca^{2+}$ and depth displayed relatively high influence on all four FFGs, while some variables such as pH, %gravel, %silt, and %bank affected specific groups. This approach can help to characterize community structure and to ecologically assess target ecosystems.

• Analytical Science and Technology
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• v.33 no.1
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• pp.23-32
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• 2020

Methamphetamine (MA) is the most common and available drug of abuse in Korea and its primary metabolite is amphetamine (AP). Detection of AP derivatives, such as MA, AP, phentermine (PT), MDA, MDMA, and MDEA by the use of immunoassay screening is not reliable and accurate due to cross-reactivity and insufficient specificity/sensitivity. Therefore, the analytical process accepted by most urine drug-testing programs employs the two-step method with an initial screening test followed by a more specific confirmatory test if the specimen screens positive. In this study, a gas chromatography-mass spectrometric (GC-MS) method was developed and validated for confirmation of MA and AP in human urine. Urine sample (500 µL) was added with N-isopropylbenzylamine as internal standard and ethyl chloroformate as a derivatization reagent, and then extracted with 200 µL of ethyl acetate. Extracted samples were analysed with GC-MS in the SIM/ Scan mode, which were screened by Cobas c311 analyzer (Roche/Hitachi) to evaluate the efficiency as well as the compatibility of the GC-MS method. Qualitative method validation requirements for selectivity, limit of detection (LOD), precision, accuracy, and specificity/sensitivity were examined. These parameters were estimated on the basis of the most intense and characteristic ions in mass spectra of target compounds. Precision and accuracy were less than 5.2 % (RSD) and ±14.0 % (bias), respectively. The LODs were 3 ng/mL for MA and 1.5 ng/mL for AP. At the screening immunoassay had a sensitivity of 100% and a specificity of 95.1 % versus GC-MS for confirmatory testing. The applicability of the method was tested by the analysis of spiked urine and abusers' urine samples.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.3
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• pp.256-260
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• 1999

Minimun-detectable levels to 28 antibacterial agents used for the prevention and the treatment of fish diseases were determined to establish optimal detective method of bioassay in fish by the EEC 4-plate method, the modified method of EEC 4-plate and the standard method of analysis in food safety regulation. The test organisms used in the methods of bioassay were as follows: Bacillus subtilis BGA (B. subtilis) and Micrococcus luteus ATCC 9341 (M. luteus) in the EEC 4-plate method, B. subtilis, M. luteus and Bacillus cereus var. mycoides ATCC 11778 (B. cereus) in the modified of EEC 4-plate, and B. subtilis, M. luteus, B. cereus and Bacillus stearothermophilis var. calidolactis C-953 (B. stearothermophilis) in the standard method. The standard method showed predominant sensitivity in the detection of penicillins (PCs), and was also highly sensitive to aminoglycosides (AGs). The sensitivity of standard method in the detection of tetracyclines (TCs), marrolides (MLs), nitrofuran derivatives(NFs) and quinolones (QNs) was very low, and against sulfonamides (SAs), however, was extremely low. The modified method of EEC 4-plate showed very high sensitivity to TCs. Both the EEC 4-plate and the modified method of EEC 4-plate showed competitively high sensitivity in the detection of PCs, MLs, NFs, QNs and SAs. All the methods studied in the experiment showed very low sensitivity against chloramphenicol (CMs). Consequently, the modified method of EEC 4-Plate was the best bioassay method with a wide range of sensitivity for the optimal detection of the residual antibacterial agents in fish.

• Korean Journal of Construction Engineering and Management
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• v.11 no.2
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• pp.54-63
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• 2010

Domestic construction companies suffer from the difficulty in financing in the wake of economic slump at home and abroad. In the periods of this economic slump, which hit the nation REITs, the facilitator of fluid financing and the stimulating of construction economic, has increasingly been expanded since its introduction in 2001. But, REITs relatively falls behinds any other nations, in terms of its growth speed and marketing volume. The purpose of this research thesis is to suggest the method for composing a portfolio using Markowitz portfolio selection models for stimulating REITs. Main contents are as follows. First, the thesis made the comparative analysis on profit increase in REITs investment in application of models by Markowitz and REITs derivatives from 2007/07/03 to 2008/07/21 during investment analysis periods. The result showed that total profits by Markowitz model amounted to about 10 percent higher than average profits of REITs derivatives. Second, this thesis made the analysis on sensitivity of data-gathering and portfolio change periods of the existing profits, in order to measure the both periods and yield optimum profits. The six month data-collecting periods of profits accounted for some 16% higher profits than profits of REITs derivatives. In case when the two week periods of portfolio change accounted for some 11% higher profits than profits of REITs derivatives.

• Analytical Science and Technology
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• v.15 no.3
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• pp.196-213
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• 2002

The alkylphenols, chlorophenols and bisphenol A were determined by gas chromatography/mass spectrometry-selected ion monitoring mode followed by three work-up methods for comparison; EPA method, isoBOC derivatization method and TBDMS derivatization method. Eleven phenols in water samples were extracted with dichloromethane. Also, solid-phase extraction (SPE) with XAD-4 and subsequent conversion to isobutoxycarbonyl derivatives or tert.-butyldimethylsilyl derivatives for sensitive analysis with the selected ion-monitoring (SIM) mode. The recoveries were 85.1~109.9% (EPA method) and 90.3~126.6% (isoBOC derivatization and TBDMS derivatization), respectively. The method detection limit of bisphenol A for SIM were 0.732 ${\mu}g/{\ell}$ (EPA method), 0.002 ${\mu}g/{\ell}$ (isoBOC derivatization) and 0.021 ${\mu}g/{\ell}$ (TBDMS derivatization). The SIM responses were linear with the correlation coefficient varying 0.9755~0.9981 (isoBOC derivatization), and 0.9908~0.9996 (TBDMS derivatization). When these methods were applied to treated wastewater sample from a polyethylene plant, the concentrations of 11 phenols were below the method detection limit.