• Journal of Power System Engineering
• /
• v.9 no.2
• /
• pp.81-87
• /
• 2005

This study is numerical analysis on the increasing temperature characteristics of vaporizer fin for liquefied natural gas with super low temperature. Existing LNG vaporizers use the direct contact heat transfer mode where the extreme super low temperature LNG of $-162^{\circ}C$ flows inside of the tubes and about $20^{\circ}C$air flows on outside of the fin. Recently, the vaporizers with great enhanced performance compared to conventional type have been developed to fulfill these requirements. The vaporizing characteristic of LNG vaporizer with air as heat source has a fixed iced. These characteristic cause a low efficiency in vaporizer, total plant cost and installing space can be increased. The vaporizing characteristics of LNG via heat exchanger with air are analytically studied for an air heating type vaporizer. This study is intended to supply the design data for the domestic fabrication of the thickness and angle vaporizer fin. Governing conservation equations for mass, momentum and energy are solved by STAR-CD based on an finite volume method and SIMPLE algorithm. Calculation parameter is fin thickness, setup angle and LNG temperature. If the vaporization performance of the early stage and late stage of operating is considered, the case of ${\phi}=90^{\circ}$ was very suitable. In this paper was estimated that the heat transfer was most promoted in case of THF=2mm.

• Journal of Environmental Science International
• /
• v.25 no.4
• /
• pp.567-577
• /
• 2016

The purpose of this study was to measure the antioxidant activity and bioactivity of black chokeberry (Aronia melanocarpa). The black chokeberry was known to contain many physiologically active substance, such as ascorbic acid, anthocyanin, quercetin. We extracted black chokeberry powder from four solvents such as chloroform:methanol(CM, 2:1, v/v), distilled water (DW), 70% ethanol, 70% methanol. After that, we determined anthocyanin, total phenol, flavonoid content, DPPH radical scavenging activity, ABTS radical scavenging activity, ferric reducing antioxidant power, reducing power and Nitrite scavenging activity of black chokeberry extracts and as results of comparing each extract. respectively. From the above results shows that antioxidant activity and bioactivity of black chokeberry extracts was the highest in 70% methanol (p<0.05). The results suggest that black chokeberry can be used as nutraceutical foods and natural antioxidant.

• Preventive Nutrition and Food Science
• /
• v.10 no.2
• /
• pp.198-205
• /
• 2005

Korean medicated diet (KMD) is not a simple combination of food and Chinese drugs, but a special carefully constructed diet made from Sasang constitutional medicines, food and condiments under the theoretical guidance of diet preparation based on differentiation of symptoms and signs of traditional Sasang medicine (TSM). It combines the functional efficacy of medicine with the delicacy of food, and can be used to prevent and cure diseases, build up one's health and prolong one's life. Korean traditional medicated diet has a long history of development. Although influenced by Chinese medicine, Korean traditional medicine has been developed into a unique system of traditional medicine that has surpassed the continental medical practice, sublimating itself into a native medical practice suitable to Korean lifestyles and physical constitutions. In the 19th century, Lee Jema's Sasang medicine (medicine of four types of energy determining the physical constitution) was introduced. It is an integration of mind and body according to the individual's physical constitution that is categorized allowing a customized method of treatment ideal for each category-making the content of Korean traditional medicated diet even richer. The characteristics of Korean medicated diet are as follows: (1) Laying stress on the wole, selecting medicated diet on the basis of differential diagnosis. (2) Suitable for prevention and treatment, outstanding in effect. (3) Good in taste, convenient for taking. KMD refers to drink and food according to certain prescriptions, by processing and cooking that can be used either for prevention and cure of diseases, or for health care and recovery. The purpose of this review is to introduce TSM and KMD based on Sasang constitutional medicines.

• KEPCO Journal on Electric Power and Energy
• /
• v.1 no.1
• /
• pp.15-20
• /
• 2015

To examine the magnetic shielding effect for carbon-based materials at extremely low frequencies (60 Hz), two types of carbon black (Super-P and Denka Black) and a natural graphite (HC-198) were mixed into organic binder at 10 wt.% to produce a coating solution, and a powder coating with varying thickness was applied on an aluminum disk measuring 88 mm in radius. A device was developed to measure the sheielding effect at extremely low frequencies. A closed circuit was achieved by connecting a transformer and a resistor. The applied voltage was fixed at 65 V, and the magnetic field was measured to being the range of 4.95~5.10 mG. Depending on the thickness of the coating layer, the magnetic field showed a decreasing trend. The maximum decrease in the magnetic field of 38.3% was measured when natural graphite was coated with specimens averaging $455{\mu}m$. This study confirmed that carbon-based materials enable magnetic shielding at extremely low frequencies, and that the magnetic shielding effect can be enhanced by varying the coating thickness.

• Journal of Energy Engineering
• /
• v.6 no.1
• /
• pp.104-113
• /
• 1997

This study aims to develop an analysis model using a commercial process simulator-ASPEN PLUS for an IGCC (Integrated Gasification Combined Cycle) system consisting a dry coal feeding, oxygen-blown entrained gasification process by Shell, a low temperature gas clean up process, a General Electric MS7001FA gas turbine, a three pressure, natural recirculation heat recovery steam generator, a regenerative, condensing steam turbine and a cryogenic air separation unit. The comparison between those results of this study and reference one done by other engineer at design conditions shows consistency which means the soundness of this model. The greater moisture contents in Illinois#6 coal causes decreasing gasifier temperature and the greater ash and sulfur content hurt system efficiency due to increased heat loss. As the results of sensitivity analysis using developed model for the parameters of gasifier operating pressure, steam/coal ratio and oxygen/coal ratio, the gasifier temperature increases while combustible gases (CO＋H2) decreases throughout the pressure going up. In the steam/coal ratio analysis, when the feeding steam increases the maximum combustible gas generation point moves to lower oxygen/coal ratio feeding condition. Finally, for the oxygen/coal ratio analysis, it shows oxygen/coal ratio 0.77 as a optimum operating condition at steam/coal feeding ratio 0.2.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.64-64
• /
• 2010

This paper presents the results of changes of optical properties of front materials in crystalline PV modules. If PV modules on the outdoor, transmittance of front materials is reduced by solar light. That is UV, IR included Solar spectrum will have change the properties of glass. Therefore decrease in transmittance leads to loss of the PV modules output. All the PV modules showed the loss in Isc by 1~5% within few hors. To investigate the changes we are analyzed using spectrophotometer from raw glass to laminated glass.

• The KSFM Journal of Fluid Machinery
• /
• v.17 no.6
• /
• pp.84-88
• /
• 2014

A long term passive cooling system is considered as the most important safety feature for the nuclear design after the Fukushima Daiichi nuclear power plant accident in 2011. The conventional active pump driven safety systems are not available during a station Black Out (SBO) accident. The current design requirement on cooling time of the Passive Auxiliarly Feedwater System (PAFS) is about 8 hours only. To meet the 72 hours cooling time, the pool capacity of cooling water tank should be increased as much as 3~4 times larger than that of current water cooling tank. In order to extend the cooling time for 72 hours, a new passive air-water combined cooling system is proposed. This paper provides the feasibility of the combined passive air-water cooling system. The current pool capacity of water cooling system is preserved, and the cooling capability is extended by an additional air cooler.

• Wind and Structures
• /
• v.14 no.3
• /
• pp.253-283
• /
• 2011

This paper presents the field measurement results of wind effects on a super-tall building (CITIC Plaza, 391 m high) located in Guangzhou. The field data such as wind speed, wind direction and acceleration responses were simultaneously and continuously recorded from the tall building by a wind and vibration monitoring system during two typhoons. The typhoon-generated wind characteristics including turbulence intensity, gust factor, peak factor, turbulence integral length scale and power spectral density of fluctuating wind speed were presented and discussed. The dynamic characteristics of the tall building were determined based on the field measurements and compared with those calculated from a 3D finite element model of the building. The measured natural frequencies of the two fundamental sway modes of the building were found to be larger than those calculated. The damping ratios of the building were evaluated by the random decrement technique, which demonstrated amplitude-dependent characteristics. The field measured acceleration responses were compared with wind tunnel test results, which were found to be consistent with the model test data. Finally, the serviceability performance of the super-tall building was assessed based on the field measurement results.

• Journal of Energy Engineering
• /
• v.5 no.1
• /
• pp.42-49
• /
• 1996

Natural gas is one of the promising alternative fuels for automotive vehicles, because it has lower exhaust emissions and better fuel economy characteristics than those of gasoline, and can be used in conventional gasoline engines without major modifications. In the present study, a conventional gasoline engine was modified to a CNG engine, which can be operated with CNG only, and an engine bench test was performed to calibrate the operating parameters of the engine such as air fuel ratio, spark advance, etc. at various operating conditions. The modified CNG engine, then, was installed on a commercial gasoline vehicle and a vehicle driving test on chassis dynamometer was performed to examine the fuel economy and exhaust emission characteristics. As a result, the prototype CNG vehicle showed lower exhaust emissions and better fuel economy characteristics, but slightly reduced brake horse power, compared to the gasoline vehicle.

• Nuclear Engineering and Technology
• /
• v.47 no.1
• /
• pp.59-65
• /
• 2015

Background: After the Fukushima accident, the importance of hazard analysis for extreme external events was raised. Methods: To analyze typhoon-induced hazards, which are one of the significant disasters of East Asian countries, a statistical analysis using the extreme value theory, which is a method for estimating the annual exceedance frequency of a rare event, was conducted for an estimation of the occurrence intervals or hazard levels. For the four meteorological variables, maximum wind speed, instantaneous wind speed, hourly precipitation, and daily precipitation, the parameters of the predictive extreme value theory models were estimated. Results: The 100-year return levels for each variable were predicted using the developed models and compared with previously reported values. It was also found that there exist significant long-term climate changes of wind speed and precipitation. Conclusion: A fragility analysis should be conducted to ensure the safety levels of a nuclear power plant for high levels of wind speed and precipitation, which exceed the results of a previous analysis.