• Analytical Science and Technology
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• v.33 no.1
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• pp.11-22
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• 2020

When extracting semi-volatile components of herbal medicines using hot water vapor, some substances may react with water vapor or oxygen, and some volatile substances may be lost, when using an organic solvent extraction method has the disadvantage that it may contain a non-volatile material and residual organic solvent. In addition, it is inefficient to separate semi-volatile substances from herbal medicines into each single component and conduct biological activity research for each component to determine the effective ingredient, and some components may be lost in the separation process. In this study, semi-volatile substances evaporated under two pressure-reduced conditions in Chinese herbal medicines such as Cnidii Rhizoma, Aucklandiae Radix and Amomum Fructus were separated by cooling with liquid nitrogen. Those were analyzed by gas chromatography-mass spectrometry (GC-MS) to identify the components, and this method may be used to study biological activities at the cellular level. The substances separated under reduced pressure, essential oil obtained by simultaneous distillation extraction (SDE) method and substances by using solid phase micro-extraction (SPME) from Cnidii Rhizoma, Aucklandiae Radix and Amomum Fructus were analyzed by GC-MS. In the case of Cnidii Rhizoma and Aucklandiae Radix, there were some differences among the essential oil components obtained by SDE and those identified by low temperature capture (CT) and SPME method, these were believed to be produced by some volatiles reacting with water or oxygen at the boiling point temperature of water.

• Journal of Aerospace System Engineering
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• v.10 no.4
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• pp.67-74
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• 2016

The primary aim for using a Korean Condition Based Maintenance (CBM) system is to maintain military operational readiness using Interactive Collection Analysis Systems (ICAS) installed on naval vessels. Other aims are to preemptively provision maintenance and supply functions, to guarantee economical management of logistical assets, and to implement data driven equipment life cycle management. In order to accomplish these aims, it is necessary to establish standard system conditions. However, because manufacturers do not provide the technology necessary for maintenance management, it is required to retain component performance maps for each piece of equipment, and to accumulate data about frequently occurring fault patterns. This study confirms the validity of component performance maps using micro gas turbines and provides accumulated data on machine break downs. This would allow real time equipment performance checks and present performance trends. Then analysis would provide solutions for maintaining the best machine operating conditions with detailed maintenance manuals for operators. This study is a basis for further research to investigate additional ways to develop CBM using data obtained from naval vessels used in actual military operations.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.537-541
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• 2009

The gas turbine engine performance is greatly relied on its component performance characteristics. Generally, acquisition of component maps is not easy for engine purchasers because it is an expensive intellectual property of gas turbine engine supplier. In the previous work, the maps were inversely generated from engine performance deck data, but this method is limited to obtain the realistic maps due to calculated performance deck data. Therefore this work proposes newly to generate more realistic compressor map from experimental performance test data. And then a realistic compressor map can be generated form those processed data using the proposed extended scaling method at each rotational speed. Evaluation can be made through comparison between performance analysis results using the performance simulation program including the generated compressor map and on-condition monitoring performance data.

• Journal of Environmental Science International
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• v.14 no.1
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• pp.71-80
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• 2005

Soil is one of the most fundamental elements as well as with water and air in studies associated with the environment, in addition, it is one of the important environmental mediums that constructs a basis of the bio­logical system and performs various roles of matter circulation. This study was carried out in Seoul, in May 2000 to evaluate variation in the concentration levels and distribution characteristics for PAH compounds in soil. Soil samples were collected from 33 sites covering traffic, factory, incineration and mountain groups and the PAHs were analyzed. The results show a wide dis­tribution range of PAHs concentrations between 14.66 ng/g and 1,219.35 ng/g. The highest concentration levels exist at Sungsu-2 of the factory group (FS-2). Daemo-3 of the Mountain group (MD-3) presents the lowest levels as compared with the other sites. PAH compounds including mutagenic and carcinogenic materials show high concentrations in the traffic and factory groups and a high ratio in the mountain group. Besides, these compounds absorbed with micro particles might be spread out over a wide region associated with particles' movement and diffusion. After principal component analysis of the soil samples, the results indicated that the sources of PAHs in the soil were divided into two groups, pesticides and vehicles.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.1
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• pp.80-88
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• 2013

In currently developed engine condition monitoring systems, most field engine maintenance engineers have difficulties to use them in fields due to complexity, unpractical use, lack of understanding, etc. Therefore a practical usable engine condition monitoring system must be needed. This work proposes a practical performance condition monitoring of a small turbojet engine through comparing between the on-line performance monitoring data and the initial clean performance data calculated by the base engine performance model. Moreover the proposed monitoring system checks the gas path components' on-line health condition through comparing the component performance characteristics between the running engine represented as a deteriorated engine or a degraded engine and the base engine performance model represented as a clean engine. The proposed condition monitoring system is coded in a friendly GUI type program for easy practical application by a commercial tool, MATLAB/SIMULINK and LabVIEW.

• Applied Microscopy
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• v.40 no.3
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• pp.147-154
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• 2010

The aim of this study is to determine microstructure, chemical composition and crystal structure of hydroxyapatite for mouth teeth using optical microscopy and electron microscopy as well as electron probe micro-analysis (EPMA). Enamel, a protective cover to the teeth, consisted of rods oriented in regular and had relatively higher crystallinity and Ca component. In contrast, dentin showed a sponge-like microstructure with circular holes which were passages of dentinal tubules, and had higher Mg component than the enamel region due to its higher organic content. Hydroxyapatite crystals appeared as large rods in enamel, but as small needles in dentin. Their electron diffraction patterns were different by their crystallinity as well as by the organic content of the matrix.

• 한국문화재보존과학회:학술대회논문집
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• 2004.10a
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• pp.137-153
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• 2004

We have analyzed the ingredients of 17 pieces of Bronze Age bronze ware, and an additional 22 pieces of Koryo and Chosun dynasty bronze ware. We have also conducted analysis of the extraction sites where these bronze ware items were found. For analyzing the main ingredient the bronze ware items have been divided into 3 groups - Cu-Sn(70?75:20), Cu-Pb-Sn(70:10:10), Cu-Pb-Sn(60:10:20) type respectively. In tile cases of the Cu-Pb-Sn groups the division comes down to differences in the Cu content as the main component, and elements such as Ni, Fe, Co contribute as a micro ingredient. The geographical and periodic characteristics of ancient bronze ware items show that theircompositional element changes from Cu:Sn to Cu:Pb:Sn and the Cu content decreases with the period,while the Pb content increases with the period. Bronze ware items from Suchon Ri, Gongju (that were used in 3 B.C.) form very different categories from 3rd ${\~}$ 2nd B.C.. They additionally formed very different categories from those bronze ware items analyzed in this research. These bronze ware itemsare shown to be geographically close and periodically overlapped, but made of a new elemental composition. This shows an inflow of a production technical culture present in the new bronze wares. The main component content of Cu is lower, and the Co and Fe contents (as microelements) are much higher than that of other bronze ware items. Such facts showthat those bronze ware items used completely different materials from bronze ware items in other cultural areas, or that there were differences in smelting techniques In the places where ancient bronze ware items have been extracted, it is presumed that the materials originated from the southern parts of Korea andnorthern parts and southern parts of China. .As more bronze ware scientific research is compiled one can conclude that that there will be enough scientific evidence to study the Bronze Age culture of Koreasystematically.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.7
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• pp.874-880
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• 2007

Volatile flavor compounds of 4 grape species (Campbell, Sheridan, Red globe, and Meoru) were identified during 3-day storage at either $4^{\circ}C$ or room temperature. Each sample was analyzed by solid-phase micro-extraction (SPME) method combined with gas chromatography-mass spectrometry. Also electronic nose composed of 12 different metal oxide sensors was used to differentiate flavors of grapes. Sensitivities (delta $R_{gas}/R_{air}$) of sensors from electronic nose were obtained by principal component analysis (PCA). Proportion of the first principal component was 99.30% at $4^{\circ}C$ and 99.36% at room temperature, respectively. In our result, flavor patterns of grape can be differentiated according to the storage period. The major volatile flavor compounds were 1-hexanol, hexanoic acid and its ethyl ester, and phenylethyl alcohol with the presence of butanoic acid and its ethyl ester, acetic acid, benzeneacetic acid and its ethyl ester.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5150-5155
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• 2011

Alzheimer's disease (AD) and vascular dementia (VD) are the most common dementia. In this paper, we proposed a region selection for classification of AD, VD and normal (NOR) based on micro-Raman spectra from platelet. The preprocessing step is a smoothing followed by background elimination to the original spectra. Then we applied the minmax method for normalization. After the inspection of the preprocessed spectra, we found that 725-777, 1504-1592 and 1632-1700 $cm^{-1}$ regions are the most discriminative features in AD, VD and NOR spectra. We applied the feature transformation using PCA (principal component analysis) and NMF (nonnegative matrix factorization). The classification result of MAP(maximum a posteriori probability) involving 327 spectra transformed features using proposed local region showed about 92.8 % true classification average rate.

• Korean Journal of Materials Research
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• v.31 no.12
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• pp.704-709
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• 2021

In the flux used in the batch galvanizing process, the effect of the component ratio of NH₄Cl to ZnCl₂ on the microstructure, coating adhesion, and corrosion resistance of Zn-Mg-Al ternary alloy-coated steel is evaluated. Many defects such as cracks and bare spots are formed inside the Zn-Mg-Al coating layer during treatment with the flux composition generally used for Zn coating. Deterioration of the coating property is due to the formation of AlCl_x mixture generated by the reaction of Al element and chloride in the flux. The coatability of the Zn-Mg-Al alloy coating is improved by increasing the content of ZnCl₂ in the flux to reduce the amount of chlorine reacting with Al while maintaining the flux effect and the coating adhesion is improved as the component ratio of NH₄Cl to ZnCl₂ decreases. Zn-Mg-Al alloy-coated steel products treated with the optimized flux composition of NH₄Cl·3ZnCl₂ show superior corrosion resistance compared to Zn-coated steel products, even with a coating weight of 60 %.