• Natural Product Sciences
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• v.28 no.4
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• pp.168-180
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• 2022

Ephedra is a genus of the Ephedraceae family and is found in temperate regions, such as Central Asia and Europe. Among the various ephedra species, Ma Huang (Ephedra herb) is derived from the aerial parts of Ephedra sinica S tapf, Ephedra equisetina Bunge, and Ephedra intermedia Schrenk & C.A. Mey. Ma Huang contains various ephedra alkaloids, including (-)-ephedrine, (+)-pseudoephedrine, (-)-norephedrine, (+)-norpseudoephedrine, (-)-methylephedrine, and (+)-methylpseudoephedrine, which are found naturally as single enantiomers, although they can be prepared as racemates. Although the use of Ma Huang in foods is prohibited in Korea, products containing Ma Huang can be imported, and so it is necessary to develop a suitable analytical technique for the detection of Ma Huang in foods. Herein, we report the development of analytical methods for the detection of ephedra alkaloids in products containing Ma Huang. Following sample purification by solid phase extraction, quantitative analysis was performed using ultra-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS). Additionally, the enantiomers were successfully separated using HPLC-DAD. We successfully analyzed various food samples, where the ephedra alkaloids were qualitatively and quantitatively determined, and the enantiomers were separated. It is expected that these methods may contribute toward preventing the distribution of illegal products containing Ma Huang.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.1
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• pp.98-105
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• 2010

Squeal, a kind of self-excited vibration, is generated by the friction between the disc and the friction materials. It occurs at the ending stage of the braking process, and radiates and audible frequency range of 1 kHz to 10 kHz. Squeal is generated from unstability because of the coupling between the translation and rotation of the system. This instability is caused by the follower force and follower force is normal component of the friction force. In this paper modal analysis of wheel brake system was performed in order to predict the squeal phenomenon. It was shown that the prediction of system instability is possible by FEM. A finite element model of that brake system was made. Some parts of a real brake was selected and modeled. Modal analysis method performs analyses of each brake system component. Experimental modal analysis was performed for each brake components and experimental results were compared with analytical results from FEM. To predict the dynamic unstability of a whole system, the complex eigenvalue analysis for assembly modeling of components confirmed by modal analysis is performed. The finite element models of the disk brake assembly have been constructed, and the squeal noise problems have been solved by complex eigenvalue analysis. The complex eigenvalue analysis results compared with real train test.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1120-1124
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• 2007

Recently in the automotive brake industry brake squeal noise has become one of the top automotive quality warranty issues. The contact pressure is used to predict friction coupling in the brake squeal analysis. The formulation of friction coupling has performed by nonlinear static analysis prior to the complex eigenvalue analysis. This paper proposes a validation methodology of squeal analysis using modal testing and contact analysis and examines the effect of predicted contact pressure that leads to the discrepancy between unstable complex mode and squeal frequency. This studies compose a three step validation process : examining the modal characteristics of component and assembly loaded contact pressure using modal testing and FEM analysis and verifying the contact pressure distribution using nonlinear static analysis and experiment. Finally, the unstable modes from complex eigenvalue analysis and realistic squeal frequency from the noise dynamometer are investigated.

• Journal of the Korean Electrochemical Society
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• v.13 no.4
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• pp.223-234
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• 2010

In this review, the theory and applications of the complex capacitance analysis, which can be utilized in analyzing capacitor-like electrochemical systems, were summarized. Theoretically, it was suggested that the imaginary capacitance plots (Cim vs. log f) can provide a simple way to analyze electrochemical characteristics of capacitive systems, without complicated mathematical calculations. The usefulness of the complex capacitance analysis has been demonstrated by applying it to analyze EDLC characteristics of practical porous carbon electrodes, ionic conductivities inside small pores, and ionic resistances in the catalyst layers of polymer electrolyte membrane fuel cells.

• Journal of the Korean housing association
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• v.20 no.6
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• pp.119-126
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• 2009

This study focused on the analysis of residential satisfaction and environment awareness depending on the environment-friendly level on the outdoor space of the housing complexes. The purpose of this study is to present basic materials of the environment-friendly outdoor space planning of housing complexes. The major findings of the study are as follows. First, the results of the comparative analysis of the satisfaction of the outdoor space of apartment complexes show that the complexes with the most application of environment-friendly elements had higher residential satisfaction. But there was no meaningful statistical difference between the complexes with the higher level of application of the environment-friendly elements and the complexes with medium level of application. Secondly, according to a comparative analysis, the overall residential satisfaction of the apartment complexes was the same as the residential satisfaction of the outdoor space. Thirdly, the results of the correlative analysis of residential satisfaction and environmental awareness showed that the satisfaction of the apartment complexes decreases as the awareness of the environment-friendly apartment complex increases. The results of this study can be used as basic materials for environment-friendly outdoor space planning of apartment complexes.

• Analytical Science and Technology
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• v.20 no.5
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• pp.448-451
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• 2007

A new bis(dicyclohexylammonium) chromate dihydrate complex, $[(C_6H_{11})_2NH_2]_2[CrO_4]{\cdot}2H_2O$, (I), has been synthesized and its structure analyzed by FT-IR, EDS, elemental analysis, ICP-AES, and single crystal X-ray diffraction methods. The Cr(VI) complex (I) is tetragonal system, I${\bar{4}}$2d space group with a = 12.5196(1), b = 12.5196(1), c = $17.3796(3){\AA}$, a = ${\beta}$ = ${\gamma}$ = $90^{\circ}$, V = $2724.09(6){\AA}^3$, Z = 4. The crystal structure of complex (I) consists of tetrahedral chromate $[CrO_4]^{2-}$ anion, two organic dicyclohexylammonium $[(C_6H_{11})_2NH_2]^+$ cations and two lattice water molecules. The chromate anion and protonated dicyclohexylammonium cation is mainly constructed through the ionic bond. The cyclohexylammonium rings of the dicyclohexylammonium cation take the chair form and vertical configuration with each other. The N-H${\cdot}$O and O-H${\cdot}$O hydrogen bond networks between the $N_{dicyclohexylammonium}$, $O_{water}$ and $O_{chromate}$ atom lead to self-assembled molecular conformation and stabilize the crystal structure.

• The Journal of the Korea Contents Association
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• v.21 no.8
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• pp.184-200
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• 2021

This study proposes to secure the necessity and possibility of creating a footwear-only district utilizing the Kaesong Industrial Complex, a special economic zone in the North Korea. This is a policy proposal to explore strategic values for revitalizing the Korean footwear industry through a win-win cooperation model between the South and North Korea. With SWOT-AHP analysis method, we are planning to establish a strategy to utilize the footwear-only complex in Kaesong Industrial Complex for sustainability of the footwear industry. It presents a direction to overcome the industrial structural problems that the domestic footwear industry is facing with the aspect of the possibility of inter-Korea cooperation. As a result of the analysis, the 'SO strategy' is a proposal to establish inter-Korea cooperation K-shoe belt through footwear clusters in the two Koreas. The 'WO strategy' is an internationalization strategy of the Kaesong footwear-only complex. The 'ST strategy' is the use of flexible governance in the creation of a footwear-only complex for the relief of sanctions against North Korea. The 'WT strategy' is a paradigm shift in the perception of the peace economy in the footwear industry of inter-Korea for the re-opening of the Kaesong Industrial Complex.

• Korea Real Estate Review
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• v.28 no.3
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• pp.37-52
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• 2018

This paper analyzed the relative efficiency of industrial complexes by type based on the DEA Model. In this analysis, the output and exports of 287 industrial complexes in 2017 were used as output variables, while the industrial land area and the number of employees in the same year were used as input variables. The results of the relative efficiency of industrial complexes by type were as follows: The relative efficiency of industrial complexes was affected mainly by type and the operating period of industrial complexes. In the types of industrial complexes, the most efficient industrial complex was the Urban, high-tech industrial complex, followed by the National industrial complex and the General industrial complex. Therefore, high-tech innovation and government support for industrial complexes would be necessary to increase the efficiency of industrial complexes. In the operation period of industrial complexes, relative efficiencies increased with longer operation periods. To maximize the regeneration effect of the old industrial complex, efficiency must be kept as a priority item of the old industrial complex regeneration project.

• YAKHAK HOEJI
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• v.55 no.5
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• pp.419-425
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• 2011

To secure the good quality of pharmaceutical products, dissolution specifications for Octylonium bromide tablets and Pinaverium bromide tablets are needed to be established, which are enrolled in KPC (Korea Pharmaceutical Codex) with having no appropriate specifications. For establishing dissolution specifications, a number of experiments based on the "Guideline of Dissolution Testing for Solide Oral Dosage Forms" were performed. The results of this study will be used for revising KPC and it is expected to contribute to the incessant production of quality ensured drugs.

• Journal of Environmental Impact Assessment
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• v.21 no.3
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• pp.417-429
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• 2012

In this study, a diagnostic wind model, CALMET and a micrometeorological numerical model, ENVI-MET were used to analyze the wind field in and out of the site designated for the industrial complex around Buron-myeon, Wonju, Gangwon-do. The results of modeling with CALMET showed that the air flow in industrial complex was little affected by the surrounding terrain. And the result of wind field analysis with ENVI-MET showed there are turbulent air flows such as cavity and wake around structures in the industrial complex, which can cause high-air pollution. Therefore, it is necessary to design the industrial complex considering the wind path according to wind directions.