• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.217-227
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• 2000

The permalloy soft magnet was produced by powder injection molding process. Rheological characteristics of mixtures, debinding conditions and the magnetic properties of permalloy after sintering ware investigated. The permalloy soft magnet with a permeability of 14200 could be obtained by preparing a mixture with a powder loading of 65.4 vol.% and PP/PEG binder system, solvent extraction, thermal debinding and subsequent sintering at 1350 $^{\circ}C$ in hydrogen. The permalloy soft magnet sintered in hydrogen showed a 95 % of theoretical density and a magnetic induction of 13.2 kG at the applied magnetic field of 50 Oe

• Korean Journal of Medicinal Crop Science
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• v.26 no.2
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• pp.148-156
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• 2018

Background: Hot steaming is known to be effective in improving the biological activities of plant extracts by breaking down useful compounds to low molecular weight ones. Methods and Results: This study aimed to develop an optimal extraction and steam processing method for enhancing the low molecular ginsenoside contents of the adventitious roots culture of wild mountain ginseng. The total ginsenoside was optimally extracted when 70% EtOH was used at $50^{\circ}C$, whereas low molecule ginsenoside such as Rg2, Rh1, Rh4 and Rk1 could be extracted using 70% EtOH at $70^{\circ}C$. The adventitious roots culture of wild mountain ginseng is known to contain four major ginsenosides, i.e., Rb2, Rb1, Rg1 and Rd, however new ginsenosides Rg6, Rh4, Rg3, Rk1 and Rg5 were new abundantly obtaind after steam processing method was applied. The contents of total ginsenosides were the highest when thermal steam processing was conducted at $120^{\circ}C$ for 120 min. Unlike ginsenosides such as Rg1, Re, Rb1, Rc, Rb2, and Rh1, which decreased after steam processing, Rg3, Rk1, and Rg5 increased after thermal processing. Steam processing significanltly reduced the content of Rb1, increased that of Rg6 by about ten times than that in the adventitious roots culture of wild mountain ginseng. Conclusions: Our study showed that the optimal extraction and steam processing method increased the content of total ginsenosides and allowed the extraction of minor ginsenosides from major ones.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.915-920
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• 2001

A spent fuel problem has prevented the nuclear power from claiming to be a completely clean energy source. The nuclear transmutation technology to incinerate the long lived radioactive nuclides and produce energy during the incineration process is believed to be one or the best solutions. HYPER(Hybrid Power Extraction Reactor) is the accelerator driven transmutation system which is being developed by KAERI(Korea Atomic Energy Research Institute). Some major feature of HYPER have been developed and employed. On-power fueling concepts are employed to keep system power constant with minimum variation of accelerator power. A hollow cylinder-type metal fuel is designed for the on-line refueling concept. Lead-bismuth(Pb-Bi) is adopted as a coolant and Spallation target material. HYPER is a subcritical reactor which needs an external neutron source. 1GeV proton beam is irradiated to Lead-bismuth(Pb-Bi) target inside HYPER, and spallation neutrons are produced. When proton beams are irradiated, much heat is also deposited in the Pb-Bi target and beam window which separates Pb-Bi and accelerator vacuum. Therfore, an effective cooling is needed for HYPER target. In this paper, we performed the thermal-hydraulic analysis of HYPER target using FLUENT code, and also calculated thermal and mechanical stress of the beam window using ANSYS code.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.232-237
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• 2008

The integration of PV modules into building facades or roof could raise their temperature that results in the reduction of PV system's electrical power generation. Hot air can be extracted from the space between PV modules and building envelope, and used for heating in buildings. The extraction of hot air from the space will enhance the performance of BIPV systems. The solar collector utilizing these two aspects is called PV/T(photovoltaic/thermal) solar collector. This research is about the development of solar roof system with PV/T collector to apply into buildings. A test cell experiment was performed with the PVT roof installed: It found that the hot air supply from the PVT air collector contributed to increase the heating efficiency by 2 times and the electrical efficiency by about 8%.

• Applied Science and Convergence Technology
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• v.27 no.3
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• pp.47-51
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• 2018

We fabricated an anode-type ion beam source and studied its driving characteristics of the initial extraction of ions using two driving mechanisms: a diffusion phenomenon and a charge repulsion phenomenon. For specimen exposed to the ion beam in two methods, the surface impurity element was investigated by using X-ray photoelectron spectroscopy. Upon Ar gas injection for plasma generation the ion beam source was operated for 48 hours. We found a Fe 2p peak 5.4 at. % in the initial ions by the diffusion mechanism while no indication of Fe in the ions released in the charge repulsion mechanism. As for a long operation of 200 min, the temperature of ion beam sources was measured to increase at the rate of ${\sim}0.1^{\circ}C/min$ and kept at the initial value of $27^{\circ}C$ for driving by diffusion and charge repulsion mechanism, respectively. In this study, we confirmed that the ion beam source driven by the charge repulsion mechanism was very efficient for a long operation as proved by little electrode damage and thermal stability.

• Corrosion Science and Technology
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• v.19 no.1
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• pp.31-36
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• 2020

An efficient wet process approach to modifying natural graphite (NG) electrodes for Li-ion batteries is introduced in this paper. With homogeneous mixing and thermal decomposition of NG with diammonium phosphate ((NH₄)₂HPO₄), phosphorus and nitrogen were successfully incorporated into the surface layer of NG particles. Electron microscopy and X-ray photoelectron spectroscopy analyses demonstrated that the surface was well modified by this process. As a result, the treated NG electrodes exhibited much improved electrochemical performance over pristine NG at two different temperatures: 25 ℃ and 50 ℃. Excellent capacity retention of 95.6% was obtained after 100 cycles at 50 ℃. These enhanced properties were confirmed in a morphology analysis on the cross-sections of the NG electrodes after galvanostatic cycling. The improved cycle and thermal stabilities can be attributed to the surface treatment with phosphorus and nitrogen; the treatment formed a stable solid electrolyte interphase layer that performed well when undergoing Li insertion and extraction cycling.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.153-160
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• 2018

An environmentally favorable (chlorine-free) solid oxidizer, guanidinium dinitramide [GDN; $NH_2C(NH_2)NH_2N(NO_2)_2$], was newly synthesized from guanidine carbonate [$NH_2C(=NH)NH_2{\cdot}1/2H_2CO_3$]. Two different crystalline forms (${\alpha}-type$ and ${\beta}-type$) appeared according to the applied solvents and synthesis conditions. Moisture, during extraction, might become trapped in a crystal between inner molecules. Therefore, despite having the same chemical composition, Raman-IR and TGA-DSC revealed different physical characteristics of the two forms. Peaks of Raman shift near $1000cm^{-1}$ implied different chemical structures. Thermal analysis revealed an exothermic temperature $155.7^{\circ}C$ for ${\alpha}-type$ but one of $191.6^{\circ}C$ for ${\beta}-type$. The caloric value of ${\alpha}-type$ was 536.4 J/g, which was 2.5 times larger than that of the ${\beta}-type$, which was 1310 J/g. While the synthesized GDN of ${\alpha}-type$ showed a steep exothermic decomposition, the ${\beta}-type$ was slowly decomposed after melting through an endothermic process. This work implied that despite of the same molecular formula some different core thermal properties would appear depending on synthesis conditions.

• KSBB Journal
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• v.17 no.2
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• pp.176-181
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• 2002

Astaxanthin (3,3＇-dihydroxy-${\beta}$, ${\beta}$-carotene-4-4＇-dione), a natural pigment of pink to red color, is widely distributed in nature particularly in the skin layer of salmonoids and the crust of shrimp, lobster, etc. Recently, it was produced from the yeast culture of Phaffia rhodozyma. Because of its high thermal stability and antioxidant functionality, its applications can be extended into food, cosmetics, and pharmaceutical ingredient beyond the traditional feed additive. Because of its very high lipophilicity, astaxanthin has been extracted traditionally by strong organic solvents such as chloroform, petroleum ether, acetone, etc. In this study, we developed a surfactant-based solubillization system for astaxanthin, and used it to extract astaxanthin from disrupted yeast cells. Among Tween 20, Triton X-100 and SDS, Tween 20 was identified as the most suitable surfactant in terms of extraction capacity and safety. The ethylene oxide group of Tween 20 was identified as the most significant factor to increase the HLB value that determined the extraction capacity. The effects of micelle formation condition, such as the molar ratio of astaxanthin and Tween 20, pH, and ionic strength were also investigated. pH and ionic strength showed no significant effects. The optimal molar ratio between astaxanthin and Tween 20 was 1 : 12. Antioxidant activity of astaxanthin was higher than ${\beta}$-carotene and ${\alpha}$-tocopherol. Astaxanthin in the crude extract from the yeast cell was more resistant to air and/or light degradation than pure astaxanthin, probably because of the presence of other carotenoids and lipids.

• KSBB Journal
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• v.22 no.3
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• pp.174-178
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• 2007

The aim of this study was to identifyisothiocyanates (ITCs) from wasabi (Wasabi japonica Matsum) using supercritical carbon dioxide ($SCO_2$) and to compare the composition in the extracts between $SCO_2$ and organic solvents extraction. A semi-continuous high pressure apparatus was used to extract wasabi (roots, stems and leaves) at following conditions pressure 80$\sim$120 bar, temperature $40\sim50^{\circ}C$. Ether, ethanol, chloroform and dichloromethane were used as organic solvents. The ITCs extracted by means of both separation technologies were analyzed by a gas chromatography system. As the results of study, AITC and ITCs were highly extracted at 40$^{\circ}C$ and 80 bar. To extract AITC from wasabi, $SCO_2$ extraction is more effective than organic solvents extraction, resulted in thermal degeneration and remaining of organic solvents.

• Journal of the Regional Association of Architectural Institute of Korea
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• v.20 no.6
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• pp.81-87
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• 2018

In this paper, in order to maximize the input process efficiency of the building energy simulation field, the authors developed the automatic extraction module of spatial information based BIM geometry information. Existing research or software extracts geometry information based on object information, but it can not be used in the field of energy simulation because it is inconsistent with the geometry information of the object constituting the thermal zone of the actual building model. Especially, IFC-based geometry information extraction module is needed to link with other architectural fields from the viewpoint of reuse of building information. The study method is as follows. (1) Grasp the category and attribute information to be extracted for energy simulation and Analyze the IFC structure based on spatial information (2) Design the algorithm for extracting and reprocessing information for energy simulation from IFC file (use programming language Phython) (3) Develop the module that generates a geometry information database based on spatial information using reprocessed information (4) Verify the accuracy of the development module. In this paper, the reprocessed information can be directly used for energy simulation and it can be widely used regardless of the kind of energy simulation software because it is provided in database format. Therefore, it is expected that the energy simulation process efficiency in actual practice can be maximized.