• Korean Chemical Engineering Research
• /
• v.51 no.1
• /
• pp.42-46
• /
• 2013

Extraction process of fucoxanthin from Undaria pinnatifida and stability of fucoxanthin was studied. In this study, to utilized extracted components as a functional food material, ethanol was used as a solvent. The maximum concentration of fucoxanthin was obtained when 80% ethanol solvent was used. The extraction yield of fucoxanthin increased as extraction temperature raised to $50^{\circ}C$. Water washing of raw material for 5 minutes reduced the salt content about 94%. From the experiment that fucoxanthin content reduced by 30% for 1 day storage at $70^{\circ}C$, it was demonstrated that fucoxanthin was thermal-unstable above $70^{\circ}C$. And experimental result of light- stability showed that fucoxanthin was very unstable with light.

• Korean Journal of Food Science and Technology
• /
• v.17 no.4
• /
• pp.265-270
• /
• 1985

The saponin yield and its compositional changes of red ginseng extract (RG-EXT) was investigated during extraction at various temperature for 5 times of 8 hours. The higher temperature resulted an increase in solids yield while the total saponin recovered was decreased, particularly at $100^{\circ}C$. A relatively lower thermal stability was found for protopanaxadiol saponin, one of the saponin fractions, than protopanaxatriol saponin. The compositional ratio of saponin at ginsenoside level was little affected by extraction time. The yields data showed that more than 94% of total saponin was recovered by 3$\sim$4 times of 8 hours extraction. Extraction at $80^{\circ}C$ for 4 times of 8 hours were suggested for preparation of RG-EXT from the result of this work.

• Nuclear Engineering and Technology
• /
• v.53 no.1
• /
• pp.188-198
• /
• 2021

A modern approach to nuclear energy involves reprocessing like transmutations of spent nuclear fuel products to reduce their radiotoxicity and time needed for their storage. For this purpose, they are immobilized in inert matrices made of zirconia and can be "burned" in fast neutron reactor or Accelerator Driven System. These matrices in spherical form can be obtained by sol-gel process. The paper presents a method of microspheres fabrication based on the combined Complex Sol-Gel Process and double extraction process consisting in the preparation of zirconium-ascorbate sol and simultaneous extraction of water and nitrates. The procedure allows obtaining gel microspheres with a diameter of 50 ㎛, which after heat treatment are processed into the final product. The synthesis of zirconia microspheres with Yttrium by internal gelation process is well known for over a decade now. However, the explanation and characterization of synthesis of such material by extraction of water process is rarely found. Parameters such as: pH, viscosity, shape, sphericity and crystal structure have been determined for synthesized products and semi-products. In addition, preliminary research consisting in irradiation of the obtained materials in fast and thermal neutron flux was carried out. The obtained results are presented and described in this work.

• Analytical Science and Technology
• /
• v.33 no.2
• /
• pp.76-85
• /
• 2020

A stainless-steel needle (Hamilton 90022, 22 gauge, 718-㎛ o.d., 413-㎛ i.d., 51-mm length, bevel tip) with an electrochemically coated polyaniline layer having a microbore tunnel was newly prepared as a device for headspace in-needle microextraction. For designing the needle, the polyaniline layer length was optimized, and to evaluate the extraction efficiency for polycyclic aromatic hydrocarbons, numerous cyclic voltammetry scans were conducted. In addition, the optimization of the analytical conditions (including the adsorption and desorption parameters) and the validation of the analytical method were conducted. The optimized adsorption and desorption conditions were 40 ℃ for 30 min and 230 ℃ for 60 s, respectively. Finally, in this study, a polyaniline layer was electrochemically deposited on the in-needle surface, and it exhibited good thermal stability. The needle with the polyaniline layer was repeatedly used more than 200 times during this study. This method has some advantages in terms of the extraction time, extraction efficiency, and analysis cost.

• Resources Recycling
• /
• v.26 no.3
• /
• pp.69-78
• /
• 2017

Magnesium has been used as parts of vehicles, case materials of notebook PC and mobile phone, and its demand has been increasing recently. Its extraction technologies were classified according to the two major reduction methods: the fused salt electrolysis and the thermal reduction method. A research on the extraction of magnesium from magnesite which has been being carried out at KIGAM was briefly introduced here. Magnesium was prepared using a fused salt electrolysis method through preparation of anhydrous magnesium chloride with lab scale experiments.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.1819-1824
• /
• 2006

A microlens arrays formed by thermal reflow method is attached to an OLED device and the light extraction efficiency which includes luminance and power information is determined by adjusting the area ratio and the height ratio.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.34 no.6
• /
• pp.619-627
• /
• 2016

Cells of a PV (photovoltaic) module can suffer defects due to various causes resulting in a loss of power output. As a malfunctioning cell has a higher temperature than adjacent normal cells, it can be easily detected with a thermal infrared sensor. A conventional method of PV cell inspection is to use a hand-held infrared sensor for visual inspection. The main disadvantages of this method, when applied to a large-scale PV power plant, are that it is time-consuming and costly. This paper presents an algorithm for automatically detecting defective PV panels using images captured with a thermal imaging camera from an UAV (unmanned aerial vehicle). The proposed algorithm uses statistical analysis of thermal intensity (surface temperature) characteristics of each PV module to verify the mean intensity and standard deviation of each panel as parameters for fault diagnosis. One of the characteristics of thermal infrared imaging is that the larger the distance between sensor and target, the lower the measured temperature of the object. Consequently, a global detection rule using the mean intensity of all panels in the fault detection algorithm is not applicable. Therefore, a local detection rule was applied to automatically detect defective panels using the mean intensity and standard deviation range of each panel by array. The performance of the proposed algorithm was tested on three sample images; this verified a detection accuracy of defective panels of 97% or higher. In addition, as the proposed algorithm can adjust the range of threshold values for judging malfunction at the array level, the local detection rule is considered better suited for highly sensitive fault detection compared to a global detection rule. In this study, we used a panel area extraction method that we previously developed; fault detection accuracy would be improved if panel area extraction from images was more precise. Furthermore, the proposed algorithm contributes to the development of a maintenance and repair system for large-scale PV power plants, in combination with a geo-referencing algorithm for accurate determination of panel locations using sensor-based orientation parameters and photogrammetry from ground control points.

• Carbon letters
• /
• v.11 no.2
• /
• pp.127-130
• /
• 2010

Boron doped fullerene $C_{60}$ ($B:C_{60}$) films were prepared by the thermal evaporation of $C_{60}$ powder using argon plasma treatment. The morphology and structural characteristics of the thin films were investigated by scanning electron microscope (SEM), Fourier transform infra-red spectroscopy (FTIR) and x-ray photo electron spectroscopy (XPS). The electrochemical application of the boron doped fullerene film as a coating layer for silicon anodes in lithium ion batteries was also investigated. Cyclic voltammetry (CV) measurements were applied to the $B:C_{60}$ coated silicon electrodes at a scan rate of $0.05\;mVs^{-1}$. The CV results show that the $B:C_{60}$ coating layer act as a passivation layer with respect to the insertion and extraction of lithium ions into the silicon film electrode.

• Journal of the Korean Solar Energy Society
• /
• v.22 no.1
• /
• pp.31-42
• /
• 2002

This study has been carried out to design a number of storage units which could improve the utilizability of solar energy by offering convenient means to store it. The proposed units are systematically tested to establish their reliability in actual operations. One of the prominent features of the present storage units is that each design is meant to drastically improve the thermal response of solar systems which would definitely offer extreme convenience to whoever uses it. Also sought in the present study is to elicit ideal operating conditions during the storage and extraction phases of solar energy once it is delivered to the storage unit. The present study has confirmed the potential use of the proposed units with their applicability in capitalizing the sun's energy.

• Mass Spectrometry Letters
• /
• v.5 no.1
• /
• pp.12-15
• /
• 2014

Thermal ionization mass spectrometry (TIMS) was used to determine the concentration and isotope ratio of uranium contained in samples of soil and groundwater collected from Korea. Quantification of uranium in ground water samples was performed by isotope dilution mass spectrometry. A series of chemical treatment processes, including chemical separation using extraction chromatography, was applied to the soil samples to extract the uranium. No treatments other than filtration were applied to the groundwater samples. Isotopic analyses by TIMS showed that the isotope ratios of uranium in both the soil and water samples were indistinguishable from those of naturally abundant uranium. The concentration of uranium in the groundwater samples was within the U.S. acceptable standards for drinking water. These results demonstrate the utility of TIMS for monitoring uranium in environmental samples with high analytical reliability.