• Korean Journal of Plant Resources
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• v.34 no.4
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• pp.287-296
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• 2021

Recently, the pace of global climate change has tremendously increased, causing extreme damage to crop production. Here, we aimed to examine the growth characteristics and useful components of Angelica gigas under extreme heat stress, providing fundamental data for its efficient cultivation. Plants were exposed to various experimental temperatures (28℃, 34℃, and 40℃), and their growth characteristics and content of useful components were analyzed. At the experimental site, the ambient and soil temperature were 19.38℃ and 21.34℃, ambient and soil humidity were 81.3 % and 0.18 m³/m³, solar radiation was 162.05 W/m². Moreover, the soil was sandy-clay-loam (pH 6.65), with 2.66% organic matter, 868.52 mg/kg soil available phosphate, and 0.14% nitrogen. Values of most growth characteristics, including the survival rate (85%), plant height (38.66cm), and fresh and dry weight (41.3 g and 14.24 g), were the highest at 28℃. Although the highest content of useful components was observed at 34℃ (3.24%), there were no significant differences across temperatures. Growth characteristics varied across temperatures due to detrimental effects of heat stress, such as accelerated tissue aging, reduced photosynthesis, and delay of growth. Similar content of useful components across temperatures may be due to poor accumulation of anabolic products caused by impaired growth at extremely high temperatures.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.48 no.3
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• pp.189-196
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• 2022

Plasma refers to an ionized gas that is often referred to as "the fourth phase of matter", following solid, liquid, and gas. Plasma has traditionally been utilized for industrial applications such as welding and neon signs, but its promise in biomedical fields such as cancer treatment and dermatology has lately been recognized. Indeed, due to its beneficial effects in promoting collagen production, improving skin tone, and eliminating harmful bacteria in the skin, plasma treatment constitutes an important target for dermatological research. In this study, a plasma device for cosmetic manufacturing based on nitrogen, the main component of the atmosphere, was designed and assembled. Moreover, nitric oxide (NO) was selected since is easier to follow and evaluate than other nitrogen plasma active species, and its contents were measured to perform a quantitative and qualitative evaluation of plasma. First, an injection method, using different proximities labeled "sinking" and "non sinking" treatments, was performed to test the most efficient plasma treatment method. As a result, it was observed that the formulation obtained by a non sinking treatment was more effective. Furthermore, toner and ampoule were selected as cosmetics formulations, and the characteristics of the formulation and changes in the injected plasma state were observed. In both formulations, the successful injection of NO plasma was 2 times higher in toner formulation than ampoule formulation, and it gradually decreased with time, having dissipated after a week. It was confirmed that the nitrogen plasma used did not affect the stability of the toner and ampoule formulations at low temperature (4 ℃), room temperature (25 ℃), and high temperature (37 ℃ and 50 ℃) conditions. The results of this study demonstrate the potential of plasma cosmetics and highlight the importance of securing the stability of the injected plasma.

• Korean Journal of Food Science and Technology
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• v.40 no.4
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• pp.443-448
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• 2008

In this study, black garlic was produced by aging under high temperature $(70^{\circ}C)$ and high humidity (90% RH) conditions. Then, the physiological activity and antioxidative effects of its extract were compared to those of normal garlic extract. The black garlic extract had a 2.5-fold higher total polyphenol content than that of the normal garlic extract, showing levels of 10.0 mg/g and 3.7 mg/g, respectively. At the $1,000{\mu}g/mL$ concentration, the black garlic and normal garlic extracts had electron donating abilities of 101.9% and 12.9%, respectively. For their nitritescavenging effects, the normal garlic extract showed slightly higher scavenging activity than the black garlic extract at the 5 mg/mL concentration; whereas the black garlic extract had a slightly higher effect at concentrations above 20 mg/mL. In terms of their superoxide dismutase activities, the black garlic extract showed a 10-fold higher activity as compared to the normal garlic extract at the 20 mg/mL concentration. Furthermore, at 50 mg/mL, the angiotensin converting enzyme inhibitory effects of the normal garlic and black garlic extracts were approximately 52.7% and 88.8%, respectively. These results indicate that the antioxidant activity and ACE inhibitory effects of the black garlic extract were greater than those of the normal garlic extract.

• Culinary science and hospitality research
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• v.9 no.4
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• pp.191-202
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• 2003

A growing interest in health has been leading to more interest in function of food rather than its taste and nutrition. Usually we think chemical-free or oriental food to be good for health. Yaksun is a food with herbal stuff, which reflects our desire for health and longevity and China's splendid food culture. It is based on the traditional medical thought of the Orient that both medicine and food have the same origin. Yaksun is a traditional functional or nourishing food with both nutritive and medicinal elements, which therefore provides such effects as epicurean pleasure, prevention of diseases and improvement of health. It is recorded that in China there was a dietitian in the royal court from the period of Seoju(B.C. 11∼7), who was responsible for supervising and controlling the health, nutrition and disease of an emperor. Therefore, herbal food has a very long history. Currently, there are many Yaksun stores in Japan and Taiwan as well as China, which are one of popular tourist destinations. Basically Yaksun follows the theory of the Oriental medicine. Yaksun is categorized into four(cold, cool, hot and warm) according to its temperature and into five basic tastes(bitter, sweet, pungent, salty and sour). Yaksun has the functions such as preventing diseases and aging improving internal organs, and healing diseases. In China many colleges of medicine have a department of Yaksun studies through which systematic researches have been being made since a long time ago. For Korea, the discipline of Yaksun studies is still at the beginning stage. To respond to a growing interest in health and prevent chronic adult diseases, it is required to develop a functional food by establishing a systematic theory of Yaksun and making more researches into it.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.4
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• pp.315-321
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• 2003

The integrity of the turbine rotors can be assessed by measuring the material properties at service temperature. In order to evaluate the remanent life of turbine rotor steel nondestructively, a measurement system of reversible magnetic permeability using an alternating perturbing magnetic field was constructed. We present a new non-destructive method to evaluate the remanent life of 1Cr-1Mo-0.25V steel using the value of reversible magnetic permeability. This method is based on the existence of reversible magnetic permeability in the differential magnetization around the coercive field strength. We measured the first harmonics voltage induced in a coil using a lock-in amplifier tuned to an exciting frequency. The Results of reversible magnetic Permeability and Wickers hardness on the aged samples show that the peak interval of reversible magnetic permeability (PIRMP) and Vickers hardness decreases as aging time increases. A softening curve is obtained from the correlation between Vickers hardness and the PIRMP. This curve can be used as a non-destructive method to evaluate the remanent life of turbine rotor steel.

• Journal of the Korea Institute of Building Construction
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• v.18 no.4
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• pp.321-327
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• 2018

Blast furnace slag has been actively used as a substitute for cement in the construction field with high value-added through resource recycling research. However, most of the slag cannot find a clear recycling purpose. This is because some slags contain unstable materials and are used for road-use asphalt and embankment, which are low value-added materials. Electric arc furnace reduction slag(ERS) has been reported to contain a large amount of unstable free CaO due to deoxidation and component adjustment. In this study, free CaO of ERS which is generated in Korean steelmakers is quantitatively evaluated by using ethylene glycol method. As a result of free CaO quantitative evaluation of ERS, it was confirmed that there is a big difference according to the location of each field. In addition, ERS generally existed in powder form as undifferentiated characteristics, but it was confirmed that free CaO content was different due to hydration product in aggregate form due to water treatment. In addition, free CaO is an amorphous material and its crystallization characteristics are different due to the influence of temperature when it is cooled. ERS requires a long-term aging period as it contains a lot of free CaO.

• Journal of Life Science
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• v.27 no.1
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• pp.23-31
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• 2017

This study was performed to determine the ethanol ratios (30%, 50%, 70%, and 90%) of extraction solvent of Seomaeyakssuk (Artemisia Argyi H.) prepared using different methods (drying at room temperature [D], aging at $60^{\circ}C$ for 7 days after drying [AD], and roasting for 30 min at $160^{\circ}C$ after drying [RD]). The extract yield of the D extracts was lower than that of the AD and RD extracts, but the ethanol concentration of extract solvent did not affect. The L, a, and b values of the D extracts were highest, whereas those of the AD extracts were lowest. No clear trend was observed in the ethanol ratios. The soluble solids, total phenol, total flavonoid, jaceosidin, and eupatilin contents of each extract varied significantly, with RD > AD > D. The soluble solids significantly increased by ethanol ratio of extraction solvent, but other phytochemicals contents of 50% and 70% ethanol extracts were higher than others without affecting the processing methods. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was highest (77.71%) in the 70% ethanol extract obtained from RD. 2,2-azinbis-(3-ethylbenzo-thiazoline-6-sulphonate(ABTS) radical scavenging activity was significantly higher in 30-70% ethanol extract than 90% ethanol extract from RD. The results suggest that the contents of active ingredients and radical scavenging activity of ethanol extracts from Seomaeyakssuk were highest in the RD extract using 50-70% ethanol.

• Journal of the Korea Concrete Institute
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• v.17 no.1 s.85
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• pp.77-84
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• 2005

The steel slag, a by-product which is produced by refining pig iron during the manufacture of steel, is mainly used as road materials after aging. It is necessary to age steel slag for long time in air because the reaction with water and free-CaO in steel slag could make the expansion of volume. This problem prevents steel slag from being used as aggregate for concrete. However, steel slag used in this study was controled by a air-jet method which rapidly cools substance melted at a high temperature. The rapidly-chilled method would prevent from generation of free-CaO in steel slag. This study dealt with the influence of the using rate of rapidly-chilled steel slag on flow, dosage of SP, W/C ratio, and strength of mortar by statistical experimental design. Also, the results of this experiment were approved by statistical analysis methods, such as analysis of variance and F-testing. As results of F-testing, this paper proved at $1\%$ level of significance that the more the using rate of rapidly-chilled steel slag increased, the more this affected the enhancement of flow, the decrease of dosage of SP and W/C ratio, and the development of compressive strength. Also, considering the fluidity and compressive strength of mortar, it is desirable to use $75\%$ of rapidly-chilled steel slag for river sand.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.4
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• pp.323-330
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• 2019

The 500 MW Korean standard coal-fired power plant is the largest standardized power plant in Korea and has played a pivotal role in domestic power generation for over 20 years. In addition to the aging degradation due to long term operation, the probability of failure of power generation facilities is increasing due to frequent startup and stop caused by the lower utilization rate due to air pollution problem caused by coal-fired power plants. Among them, steam piping plays an important role in transferring high-temperature & pressure steam produced in a boiler to turbine for power generation. In recent years, failure of steam piping of large coal-fired power plant has frequently occurred. Therefore, in this study, failure analysis of high pressure piping weld was conducted. We identify the damage caused by high stress due to abnormal supporting structure of the piping and suggest improved supporting structure to eliminate high stress through microstructure analysis and piping stress analysis to prevent the occurrence of the similar failure of other power plant in the case of repetitive damage to the main steam piping system of the 500 MW Korean standard coal-fired power plant.

• Elastomers and Composites
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• v.46 no.2
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• pp.144-151
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• 2011

Intermittent CSR testing was used to investigate the degradation of a hydrogenated NBR(HNBR) O-rings, and also the prediction of its life-time. The cure system of HNBR O-ring was controlled as sulfur cure and peroxide cure system. An intermittent CSR jig was designed taking into consideration the O-ring's environment under use. The testing allowed observation of the effects of friction, heat loss, and stress relaxation by the Mullins effect. Degradation of O-rings by thermal aging was observed between 100 and $120^{\circ}C$. In the temperature range of $100-120^{\circ}C$, O-rings showed linear degradation behavior and satisfied the Arrhenius relationship. The activation energy of HNBR-S was about 70.6 kJ/mol. From Arrhenius plots, predicted life-times of HNBR-S O-ring were 31.1 years and 33.7 years for 50% and 40% failure conditions, respectively. In case of HNBR-P, the activation energy was about 72.1kJ/mol, and predicted life-times were 34.0 years and 36.5 years for 50% and 40% failure conditions, respectively. The peroxide cure system showed slower degradation rate and higher activation energy than the sulfur cure system.