• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.889-892
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• 2009

A microwave plasma torch at the atmospheric pressure by making use of magnetrons operated at the 2.45 GHz and used in a home microwave oven has been developed. This electrodeless torch can be used to various areas, including industrial, environmental and military applications. Although the microwave plasma torch has many applications, we in the present work focused on the microwave plasma torch operated in pure steam and several applications, which may be used in future and right now. For example, a high-temperature steam microwave plasma torch may have a potential application of the hydrocarbon fuel reforming at one atmospheric pressure. Moreover, the radicals including hydrogen, oxygen and hydroxide molecules are abundantly available in the steam torch, dramatically enhancing the reaction speed. Also, the microwave plasma torch can be used as a high-temperature, large-volume plasma burner by injecting hydrocarbon fuels in gas, liquid, and solid into the plasma flame. Lastly, we briefly report an underway research, which is remediation of soils contaminated with oils, volatile organic compounds, heavy metals, etc.

• Journal of Advanced Marine Engineering and Technology
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• v.9 no.4
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• pp.328-338
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• 1985

When the low temperature service steels are used as materials for welded structure, some problems-brittleness and weld cracking, etc.-occur in welded part due to the change of mechanical and metallurgical characteristics resulted from the thermal cycle during the welding procedure. In this study, the experiments were conducted to investigate the change of mechanical and metallurgical characteristics of the welded part for the low temperature and high pressure service steels. Moreover, the Static and Dynamic Implant Test Method was introduced to this study in order to find out the mechnism of weld cracking. In addition, the fracture toughnesses of welded bond were inspected under the various low temperature environments. Main results obtained are as follows; 1) The effect of the hydrogen on the fatigue characteristics of the weld bond can be estimated by the new self-contrived Dynamic Implant Test equipment. 2) The fine micro-structure and low hardness in the heat affected zone can be obtained by the small heat input multi-pass welding. 3) The susceptibility of the delayed cracking is largely affected by the condition of used electrode. 4) The transition temperature of the fracture surface in weld bond appears to be higher 20 .deg. C than that in base metal.

• Journal of Surface Science and Engineering
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• v.42 no.3
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• pp.139-144
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• 2009

A microwave plasma torch at the atmospheric pressure by making use of magnetrons operated at the 2.45 GHz and used in a home microwave oven has been developed. This electrodeless torch can be used to various areas, including industrial, environmental and military applications. Although the microwave plasma torch has many applications, we in the present work focused on the microwave plasma torch operated in pure steam and several applications, which may be used in future and right now. For example, a high-temperature steam microwave plasma torch may have a potential application of the hydrocarbon fuel reforming at one atmospheric pressure. Moreover, the radicals including hydrogen, oxygen and hydroxide molecules are abundantly available in the steam torch, dramatically enhancing the reaction speed. Also, the microwave plasma torch can be used as a high-temperature, large-volume plasma burner by injecting hydrocarbon fuels in gas, liquid, and solid into the plasma flame. Finally, we briefly report treatment of soils contaminated with oils, volatile organic compounds, heavy metals, etc., which is an underway research in our group.

• The Korea Journal of Herbology
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• v.29 no.6
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• pp.1-6
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• 2014

Objectives : This study was aimed to compare Gyejibokryeong-hwan (GBH) decoctions produced using different pressure levels for various extraction times to find the optimal extraction conditions through extraction yield, total soluble solids content (TSSC), hydrogen ion concentration (pH), and the contents of chemical compounds. Methods : Decoctions of GBH were prepared under the pressure levels of 0 or $1kgf/cm^2$ for 30-180 min using water as extraction solvent. The extraction yield, TSSC, and pH were measured, and the amounts of the chemical compounds were determined using high performance liquid chromatography-photodiode array detector. Results : The higher pressure and longer extraction time increased the values of TSSC and extraction yield, while decreased the pH value. The decoctions produced in 180 min by pressurized method and produced in 150 min by non-pressurized method showed maximum values of extraction yield and TSSC with minimum value of pH. The amounts of chemical compounds showed variations in pressurized and non-pressurized decoction during overall extraction times. The influences of pressure and extraction time on extraction yield, TSSC, pH, and the contents of chemical compounds were confirmed by regression analysis, which showed that all extraction values were significantly affected by at least one of two extraction factors, pressure and extraction time. Conclusions : This study suggests that the pressure and extraction time can significantly affect the extraction efficiency of components from GBH decoctions. However, optimal extraction conditions could not be chosen due to the variation of the amounts of chemical compounds.

• The Journal of Korean Medicine
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• v.34 no.4
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• pp.12-20
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• 2013

Objectives: This study compared Gumiganghwal-tang (GGT) decoctions produced using different pressure levels for various extraction times to determine the optimal extraction conditions through hydrogen ion concentration (pH), total soluble solids content (TSSC), extraction yield, and content of chemical compounds. Methods: Decoctions were prepared by the pressure levels of 0 or $1kgf/cm^2$ for 30-180 min. The pH and TSSC were measured, the extraction yield was calculated, and the amounts of the chemical compounds were determined using high performance liquid chromatography. Results: The higher pressure and longer extraction time decreased the pH value, while those conditions increased TSSC and extraction yield: the decoction produced in 180 min by pressurized method showed the minimum value of pH, but maximum values of TSSC and extraction yield. The chemical compounds showed higher amounts in decoctions produced by non-pressurized methods than pressurized methods and their amounts were decreased over the peak extraction time in both pressurized and non-pressurized methods. The results of regression analysis confirmed the correlative influences of the pressure and extraction time on pH, TSSC, and extraction yield. Conclusions: This study suggests that pressure and extraction time influence the compositional constituents in GGT decoctions, and the non-pressurized method for 120 min should be chosen as the optimal extraction condition for the preparation of GGT decoction.

• Herbal Formula Science
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• v.22 no.2
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• pp.15-24
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• 2014

Objectives : Gwakhyangjeonggi-san (GJS) which consists of 13 herbal medicines has been used to treat gastrointestinal disorders caused by common cold. This study was performed to compare GJS decoctions produced using different pressure levels for various extraction times. Methods : Decoctions were prepared by the pressure levels of $0kgf/cm^2$ (non-pressurized) or $1kgf/cm^2$ (pressurized) for 30-180 min. The extraction yield, total soluble solid content (TSSC), and hydrogen ion concentration (pH) were measured, and the contents of the nine marker compounds were determined using high performance liquid chromatography. Results : The higher pressure and longer extraction time significantly increased TSSC value, while decreased the pH value. However, only extraction time affected the extraction yield of pressurized decoction. Variation of the amounts of chemical compounds was shown in pressurized and non-pressurized decoctions during extraction time. The result of regression analysis showed that pressure and extraction time can influence to extraction yield, TSSC, pH, and the content of chemical compounds. Conclusions : This study suggests that the pressure and extraction time can significantly affect the extraction efficiency of components from GJS decoctions.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.4
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• pp.686-692
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• 2013

Today, environmental issues have become a matter of worldwide concern. In particular, automobile industries engage in considerable research and investment to develop high-efficiency and ecofriendly cars. Most ecofriendly cars use natural gas or hydrogen gas instead of fossil fuels. In this regard, low-weight and high-pressure vessels have gradually been developed to increase the driving distance of a car. However, most pressure vessels installed in cars develop many defects over time owing to shocks sustained when the car is being driven. Such defects can cause the explosion of the pressure vessel. Therefore it is important to prevent such explosions due to internal defects. The use of shearography for measuring the internal defects of objects afford many advantages. It is a non-contact and non-destructive method, and it is not limited by the object shape. In this study, the internal defect deformation and strain of an aluminum liner that is used in a CNG bus for the fuel storage tank is measured using shearography. It is important to measure the strain and deformation in order to detect defects and repair the pressure vessel. To verify the accuracy of the shearography measurement method, the measurement results of shearography, out-of-plane ESPI, and FEM are compared quantitatively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.381-387
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• 2017

Dehydrogenation from the hydrolysis of a sodium borohydride ($NaBH_4$) solution has been of interest owing to its high theoretical hydrogen storage capacity (10.8 wt.％) and potentially safe operation. An experimental study has been performed on the catalytic reaction rate and pressure drop of a $NaBH_4$ solution over both a single microchannel with a hydraulic diameter of $300{\mu}m$ and a staggered array of micro pin fins in the microchannel with hydraulic diameter of $50{\mu}m$. The catalytic reaction rates and pressure drops were obtained under Reynolds numbers from 1 to 60 and solution concentrations from 5 to 20 wt.％. Moreover, reacting flows were visualized using a high-speed camera with a macro zoom lens. As a result, both the amount of hydrogenation and pressure drop are 2.45 times and 1.5 times larger in a pin fin microchannel array than in a single microchannel, respectively.

• Journal of Korea Foundry Society
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• v.42 no.4
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• pp.218-225
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• 2022

For hydrogen-vehicle applications (air pressure control valve housing, APCVH), an investigation was conducted to determine how micro-defects in a high- pressure die-casted Al alloy (industrial code: ALDC12) could be controlled by means of a post-treatment using an organic-based impregnation solution in order to improve the air- tightness of the die-casted Al sample. Two different impregnation solutions were proposed and its test results were compared to a imported product from Japan with respect to the processing variables used. A structural investigation of the components under study was conducted by means of computer tomography and 3D X-ray micro-CT. These observations revealed that the use of the impregnation treatment to seal micro-defects led to highly significant and beneficial changes which were attributed mainly to interconnections among inherent micro-pores. A leak test after impregnation revealed that the performance improvement rate of the die-casted Al sample was ~70% for INNO-01. Therefore, the developed impregnation solutions offer an effective strategy to control the micro-defects found in various vehicle parts via die-casting.

• Journal of the Korean Vacuum Society
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• v.7 no.1
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• pp.1-4
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• 1998

We have developed an extreme high vacuum (XHV) system using a new combination pump cpmposed of a suitably shaped NEG(Non-Evaporable Getters) in the body of a sputter-ion pump (SIP). The stainless-steel test chamber was used which had been well oxidized at $450^{\circ}C$ and already yielded XHV with a turbomolecular pumping system. The pressure was measured by a Leybold extractor gauge (EXG,limit:1~$2{\times}10^{-12}$torr, but in the ultimate pressure regionthe EXG shows an unusual sign as $-0.{\times}10^{-12}$ torr which indicates much lower pressure range than its available lower limit. These results are mainly due to the high pumping speed of NEG for hydrogen. Furthermore, use of the SIP combined with the NEG as a XHV pumping system implies the potential for actualization of the surface analysis under XHV environment, and allows one to have a chance tp meet a new world in nanometer science and technology.