• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.569-579
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• 2005

An investigation for long-term strength characteristics of crushed sand concrete using crushed sands produced in Yang-san, Kim-hae and Jin-hae that can be assumed to respectively represent eastern, middle and western suburbs of Busan has been carried out. Concrete is composed of 70~80% of aggregates in whole volume so the effect of aggregates quality to the characteristics of concrete is very important. Since 1980s, aggregates used in concrete have already been substituted crushed stone because of the exhaustion of natural gravel and sand. Crushed sand tends to increase in using quantity because of the prohibition of sea sand picking and deterioration of river sand. Crushed sand is blended with river sand in order to investigate the quality changes and characteristics of concrete as variation of blend ratio of crushed sand (n, 50, 70, 80, 90, 100%). Slump and air content were measured to investigate the properties of fresh concrete. Unit weight, compressive strength and modulus of elasticity in age of 7, 28, 60, n, 180 days were measured to investigate properties of hardened concrete. Compressive strength, unit weight and modulus of elasticity were increased with a passage of time and they are expected to keep on increasing in long-term age as well. The experimental results of the qualifies of crushed aggregates in each producing area, were all satisfied with Korea Standard. The results of the measurement of slump exposed that slump preferably decreased as mixing rate increased till 70~80% but it increased to mixing rate 70~80%. The air content was exposed that it decreased by micro filler phenomenon according to that crushed sand b)ended ratio increased. According to the result of measuring unit weight in age of 7, 28, 60, 90, 180days, it increased in accordance with that blended ratio of crushed aggregates increases. As a result of measuring compressive strength and modulus of elasticity in age of 7, 28, 50, 90, 180days, compressive strength was highest when it is 70% of blended ratio.

• Journal of Science of Art and Design
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• v.11
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• pp.5-35
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• 2007

When it comes to art, the two conflicting themes of 'scientific progress' and the 'nature' have often motivated the advent of the new mode of arts. By the late 20th century, uniform and simplified mode of arts, inspired by scientific and technological progress of that time, was gradually disillusioned by the contemporaries due to the adverse effect of science on human life. In this context, naturalism pursuing for harmony of human and the nature came up as an alternative to those living in the 21st century. The pendulum has swung from minimalism to naturalism. Though the quantitative improvement of human life cannot be denied, the uprise of such problems as environmental pollution and exhaustion of natural resources degraded the quality of human life, which, eventually, shifted the attention to the theme - 'revival of naturality.' Therefore, this thesis intends to represent the modem interpretation of the 'revival of naturality' by applying the major expressions of Art Nouveau that also emphasized naturalism. Art Nouveau found its motifs from organic figures of natural beings and put them to designs of decorative arts. This carries a historical significance in that Art Nouveau boldly revolutionized historicism, which only repeated adoption and modification of the existing modes of arts, and opened it to the modem design with new attempts to practical applications of the arts. Art Nouveau, which means 'new art', prospered from the late 19th century to the early 20th century, and even after one century, it is highly appreciated, reviving as novel and vivid forms in this contemporary art. Art Nouveau based on naturalism has revisited our contemporary period when naturalism and feminized romanticism came into fashion and its common motifs revive in different jenre of arts such as fashion, furniture, glass works, and jewelry works. This study illustrates and analyzes the works of four major artists who gave a specific attention to botanical motifs of Art Nouveau and applies decorative beauty of highly sophisticated and organic curved lines and the expressional forms of botanical figures to design. Art Nouveau proved this; the nature herself is as beautiful as she can be. Within Art Nouveau, the true humanism can be revitalized with the 'revival of naturality'. This study rediscovered the boundless potential of modern interpretation and application of Art Nouveau in decorative art and design.

• Sleep Medicine and Psychophysiology
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• v.8 no.2
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• pp.129-137
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• 2001

Objectives: The purpose of this study is to investigate the effects of 38-hour sleep deprivation on fine motor performance. The Motor Performance Series (MPS) in the Vienna Test System (computerized neurocognitive function tests) was used in this study. Methods: Twenty four subjects participated in this study. Subjects had no past history of psychiatric disorders and physical illness. Subjects had normal sleep-waking cycle without current sleep disturbances and were all right-handed (Annett's Hand Preference Questionnaire: above +9 points). To minimize the learning effects, familiarization with the Vienna Test System was performed one day before the study. Subjects were to get up at 6:00 in the morning after getting enough sleep according to his or her usual sleep-wake cycle. After awakening, subjects remained awake for 38 hours under continuous surveillance. During two consecutive study days, the subjects tested MPS at 7 AM and 7 PM each day, which means the MPS was done four times in total. During the experiment, anything that could affect the subjects' sleep such as coffee, tea, alcohol, a nap, tiring sports, and all medications were prohibited. Results: In MPS, the fine motor functions of both hands decreased after 38 hours of sleep deprivation. The decrement in motor performance was prominent in the dominant right hand. In the right hand, the total number of tapping was reduced (p<.005), and the number of misses (p<.05) and the length of misses (p<.05) of line tracking, the total length of inserting a short pin (p<.01), the total length of inserting a long pin (p<.05), and the number of misses in aiming (p<.05) increased. Such performance decrement was distinct in the morning sessions. Conclusions: These results suggest that fine motor performance decrement during sleep deprivation is predominant in the right hand, which exerts maximal motor function. The finding of decrement in motor function in tapping during sleep deprivation also suggested that the time required for exhaustion of muscles is shortened during sleep deprivation. More deterioration of motor performance was shown in the morning, which could be explained as circadian rhythm effects.

• Journal of Korea Society of Industrial Information Systems
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• v.24 no.5
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• pp.9-16
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• 2019

In today's global energy market, the importance of green energy is emerging. Hydrogen energy is the future clean energy source and one of the pollution-free energy sources. In particular, the fuel cell method using hydrogen enhances the flexibility of renewable energy and enables energy storage and conversion for a long time. Therefore, it is considered to be a solution that can solve environmental problems caused by the use of fossil resources and energy problems caused by exhaustion of resources simultaneously. The purpose of this study is to efficiently produce hydrogen using plasma, and to study the optimization of DME reforming by checking the reforming reaction and yield according to temperature. The research method uses a 2.45 GHz electromagnetic plasma torch to produce hydrogen by reforming DME(Di Methyl Ether), a clean fuel. Gasification analysis was performed under low temperature conditions ($T3=1100^{\circ}C$), low temperature peroxygen conditions ($T3=1100^{\circ}C$), and high temperature conditions ($T3=1376^{\circ}C$). The low temperature gasification analysis showed that methane is generated due to unstable reforming reaction near $1100^{\circ}C$. The low temperature peroxygen gasification analysis showed less hydrogen but more carbon dioxide than the low temperature gasification analysis. Gasification analysis at high temperature indicated that methane was generated from about $1150^{\circ}C$, but it was not generated above $1200^{\circ}C$. In conclusion, the higher the temperature during the reforming reaction, the higher the proportion of hydrogen, but the higher the proportion of CO. However, it was confirmed that the problem of heat loss and reforming occurred due to the structural problem of the gasifier. In future developments, there is a need to reduce incomplete combustion by improving gasifiers to obtain high yields of hydrogen and to reduce the generation of gases such as carbon monoxide and methane. The optimization plan to produce hydrogen by steam plasma reforming of DME proposed in this study is expected to make a meaningful contribution to producing eco-friendly and renewable energy in the future.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.10
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• pp.1409-1416
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• 2012

This study examined the effects of four herbal sports drinks containing Prunus mume, Liriope platyphylla, and Acanthopanax senticosus fruit extracts on body fat and endurance of rats trained by a progressive loaded exercise program. Forty male Sprague-Dawley rats (6 weeks old) were divided into five groups and fed experimental diets for 6 weeks according to the following protocol: C, exercise-trained control group (n=8); A, exercise group with Acanthopanax senticosus extract (n=8); L, exercise group with Liriope platyphylla extract (n=8); PA, exercise group with Prunus mune fruit extract plus Acanthopanax senticosus extract (n=8); PL, exercise group with Prunus mune fruit extract plus Liriope platyphylla extract (n=8). Endurance was measured by a progressive loaded exercise test using a treadmill. PA and PL supplementation significantly extended time to exhaustion compared to the control group (p<0.05). Further, the four herbal sports drinks all significantly reduced epididymal and interscapular white adipose tissue weights compared to the control group (p<0.05). Plasma triglyceride concentration was significantly lower in the A group compared to the control group. Plasma free fatty acid concentration was higher in the A group compared to the control group. On the other hand, Acanthopanax senticosus fruit extract supplementation tended to reduce the plasma glucose concentration compared to the control group. PA and PL supplementation significantly increased gastrocnemius muscle LDH activities compared to the control group (p<0.05). These results show that sports drink containing Acanthopanax senticosus improved endurance capacity, plasma lipids, and glucose concentrations. Sports drink with Prunus mume and Liriope platyphylla or Acanthopanax senticosus was synergistically improved endurance.