• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.1 s.53
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• pp.78-87
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• 2009

When the steel slag is utilized to the concrete as the alternative fine aggregate, its use is limited as the concrete aggregate because of expansibility caused by much quantity of free CaO. So, this study is intended to examine the characteristics of the concrete which uses the rapidly cooled steel slag whose content of free CaO is sharply reduced by rapidly cooling the steel slag as the fine aggregate. Accordingly, by comparing and considering the results of the concrete slump loss test with the different substitution ratio and fine aggregate ratio of rapidly cooled steel slag, hydration by XRD and SEM analysis, compressive test by age, a length variation test and rapid chloride ion penetration test, the rapidly cooled steel slag's proper substitution ratio and the fine aggregate ratio was derived.

• Composites Research
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• v.26 no.4
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• pp.254-258
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• 2013

Polypropylene films reinforced with multi-walled carbon nanotubes and exfoliated graphite nanoplatelets were fabricated by extrusion, and the effects of filler type and take-up speed on the mechanical properties and microstructure of composite films were investigated. Differential scanning calorimetry revealed that the addition of carbon nanomaterials resulted in increased degree of crystallinity. However, increasing the take-up speed reduced the degree of crystallinity, which indicates that tension-induced orientations of polymer chains and carbon nanomaterials and the loss of degree of crystallinity due to rapid cooling at high take-up speeds act as competing mechanisms. These observations were in good agreement with tensile properties, which are governed by the degree of crystallinity, where the C-grade exfoliated graphite nanoplatelet with a surface area of $750m^2/g$ showed the greatest reinforcing effect among all types of carbon nanomaterials used. Scanning electron microscopy was employed to observe the carbon nanomaterial dispersion and orientation, respectively.

• Advances in aircraft and spacecraft science
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• v.4 no.1
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• pp.37-52
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• 2017

Gas turbines operating in dusty or sandy environment polluted with micron-sized solid particles are highly prone to blade surface erosion damage in compressor stages and molten sand attack in the hot-sections of turbine stages. Commercial/Military fixed-wing aircraft engines and helicopter engines often have to operate over sandy terrains in the middle eastern countries or in volcanic zones; on the other hand gas turbines in marine applications are subjected to salt spray, while the coal-burning industrial power generation turbines are subjected to fly-ash. The presence of solid particles in the working fluid medium has an adverse effect on the durability of these engines as well as performance. Typical turbine blade damages include blade coating wear, sand glazing, Calcia-Magnesia-Alumina-Silicate (CMAS) attack, oxidation, plugged cooling holes, all of which can cause rapid performance deterioration including loss of aircraft. The focus of this research work is to simulate particle-surface kinetic interaction on typical turbomachinery material targets using non-linear dynamic impact analysis. The objective of this research is to understand the interfacial kinetic behaviors that can provide insights into the physics of particle interactions and to enable leap ahead technologies in material choices and to develop sand-phobic thermal barrier coatings for turbine blades. This paper outlines the research efforts at the U.S Army Research Laboratory to come up with novel turbine blade multifunctional protective coatings that are sand-phobic, sand impact wear resistant, as well as have very low thermal conductivity for improved performance of future gas turbine engines. The research scope includes development of protective coatings for both nickel-based super alloys and ceramic matrix composites.

• Journal of the Korean Institute of Gas
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• v.22 no.3
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• pp.32-37
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• 2018

Recently, the distributed power generation market using natural gas is expected to expand gradually according to the government's future energy conversion policy. Distributed power generation means small power generation source near the power demand site, which has the advantage of reducing the construction costs of the transmission and distribution infrastructure, operating cost and power loss. A typical example of distributed generation using natural gas is the trigeneration system. In this study, we conducted a basic study on the performance analysis of trigeneration desiccant system for dehumidifying / cooling / heating in the air conditioner room by using the cold and engine waste heat energy generated in the trigeneration system. It shows that the system efficiency increases and the energy consumption decreases as the temperature difference between the inlet and outlet of the trigeneration system increases compared with the general air conditioning system.

• Economic and Environmental Geology
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• v.19 no.2
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• pp.147-151
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• 1986

K-Ar ages on biotites have been determined from the Proterozoic Buncheon and Hongjesa granitic rocks in comparison with the Rb-Sr whole-rock ages to investigate the ages of metamorphic events. The Rb-Sr whole-rock ages determinations on the Buncheon and Hongjesa granitoid rocks were previously reported as 2,100Ma and 1,700Ma, respectively. K-Ar ages on biotites separated from the studied rock have revealed three different age groups such as 1) 1,200~1,300Ma, 2) 600~700Ma and 3) 300~400Ma. The Rb-Sr whole-rock ages for the granitic rocks represent the time of emplacement, whereas the K-Ar ages on biotites generally indicate the time of metamorphism or alteration. The large discordance in the two age systems may not be explained as indicating the cooling period of the granitic batholiths. The K-Ar ages on biotites from the granitoid rocks might not be simply interpreted as the age of the last phase of metamorphism, since the granitic rocks had been undergone multistages of amphibolite facies-metamorphism in the Precambrian period. During the multistages of intermediate grade metamorphism, $^{40}Ar$-loss could be inevitably taken place as the metamorphic temperatures went up above the blocking temperature of biotite ($300{\pm}50^{\circ}C$). The results of the K-Ar dating on biotites from this study are probably minimum ages or hydrothermal alteration ages.

• Economic and Environmental Geology
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• v.40 no.6
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• pp.833-841
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• 2007

The groundwater heat pump system(GWHP) is one of the most efficient ground source heat pump system(GSHP) which uses low grade and shallow geothermal energy for cooling and heating purpose. The GWHP system shall be designed properly based on peak block load performance and optimum pumping rate of groundwater comparable to ground coupled heat pump system(GCHP). The optimum pumping rate depends on groundwater temperature at a specific site, size of plate heat exchanger, and total head loss occurred by whole system comprising pumps and pipings. The required optimum flow rates of the system per RT are ranged from 3.8 to 9.8lpm being less than the typical building loop flow of 9.5 to 11.4lpm.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.5
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• pp.1346-1351
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• 2007

Crohn' disease is an auto-immune disease characterized by intermittent chronic diarrhea, high fever, weight loss, abdominal spastic pain or abdominal discomfort which is followed by granulomatous necrosis and cicatrical inflammation. It is also called segmental enteritis or granulomatous enteritis. In western medicine the exact cause is undefined, however it is presumed as an immunological unbalance in alimentary tract commoonly occured in ileum portion of small intestitine or ascending colon and therefore immuno suppressive agents(usually steroids) and anti-inflammatory drugs are prescribed. In case of emergency such as ileus, perforation of intestinal wall surgical methods are considered. In oriental medicine this falls under the category of diarrhea(泄瀉), dysentery(痢疾), splenic diarrhea(脾泄). As to the pathological mechanism the abnormal ascending and descending circulation of stomach and splenic energy(脾不升淸, 胃不下降) the hepatic stagnation(肝鬱氣滯) and dysfunction of small intestine in expelling urine and feces(小陽淸獨不利) all together causes such condition. Main treatments are inducing diuresis(利小便), warming kindey to reinforce yang(溫賢助陽), nourishing the middle energy to invigorate spleen(補中健脾), elimination of the dampness by cooling(淸熱燥濕). In this case the patient was diagnosed as soyangyin(少陽人) constitution and herb medicine soyangyin Hyongbangjihwan-tang(少陽人 荊防地黃湯), Sa-am acupuncture Sojangjeonggyeok(小腸政格) was applied. There was an significant improve in chief complaints and general conditions.

• Journal of the Korean Society of Food Culture
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• v.32 no.3
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• pp.227-234
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• 2017

This study attempted to establish the optimal conditions for storage of spring kimchi cabbage to stably control supply and demand. To this end, this study stored kimchi cabbages in various manners for different periods and compared the quality characteristics of kimchi using these cabbages. According to the results, pre-drying with photocatalytic and pre-cooling treatments showed average selectivity loss rates of 18.83 and 21.37%, respectively, which were lower than those of other treatments. Spring kimchi cabbages were stored for 15 weeks under various conditions, and the kimchi was stored for 4 weeks at $4^{\circ}C$. After ripening, each kimchi was analyzed for their soluble solid content, pH, acidity, and salinity. The average pH of kimchi was 4.60 and tended to rise, whereas average acidity was 0.38% and fell by 0.24 to 0.31% as the storage period was extended. Extension of the storage period caused decreases in soluble solid content and salinity, and the number of lactic acid bacteria decreased due to increased pH and reduced acidity (p<0.05). Sensory evaluation showed that all experts and non-professionals preferred kimchi treated by precooling compared to any other treatment.

• Food Science and Preservation
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• v.14 no.1
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• pp.109-112
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• 2007

Precooling and improved packing of mushrooms were investigated with a view to prolonging their freshness. Harvested mushrooms were precooled by forced air cooling and then packed in an EPS container. Mushrooms were transported to customers by insulated truck and stored at either $10^{\circ}C\;or\;25^{\circ}C$. Conventionally packed mushrooms in cartons were also examined as controls. Mushroom respiration rate slowly fell 2- to 3-fold upon precooling. Weight loss was decreased by precooling and the use of the insulated pack. Also, the L-value of the mushroom surface remained high with precooling, and mushroom elongation was less than in the control. Summer market life was extended to 3-4 days (from 1-2 days) by the improved distribution method.

• Journal of Radiation Protection and Research
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• v.20 no.1
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• pp.53-64
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• 1995

The radiation fields following the large loss of coolant accident (LOCA) have been assessed for the vital areas in the service building of Wolsong 2, 3, and 4 nuclear power plants. The ORIGEN2 code was used in calculating the fission product inventories in the fuel. The source terms were based upon the activity released following the dual failure accident scenario, i.e., a LOCA followed by impaired emergency core cooling (ECC). Configurations of the reactor building, the service building, and the ECC system were constructed for the QAD-CG calculations. The dose rates and the time-integrated doses were calculated for the time period of upto 90 days after the accident. The results showed that the radiation fields in the vital access areas were found to be sufficiently low. Some areas however showed relatively high radiation fields that may require limited access.