• Journal of Korean Society of Steel Construction
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• v.26 no.3
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• pp.177-189
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• 2014

When floor vibration problems occur in existing buildings, TMD (tuned mass damper) can be a viable alternative to resolving the problem. Only when TMD has been exactly tuned to the natural frequency of the floor, it can control the vibration as intended in design. However, TMD gets inefficient in the situation where the natural frequency changes as a result of the uncontrollable variation of the floor mass weight. This physical phenomenon is often called as TMD-off-tuning. This study proposes asymmetric TMD for enhancing the robustness of floor vibration control against uncertain natural frequencies. The proposed TMD features two asymmetric linear springs such that the floor vibrational energy can be dissipated through both the translational and rotational motion. An easy-to-use graphical optimization method was developed in this study. The asymmetric TMD proposed outperformed in vibration control by 28% compared to that of conventional TMD. The robustness of asymmetric TMD of this study was two times higher than that of conventional TMD.

• Resources Recycling
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• v.29 no.1
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• pp.25-34
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• 2020

Electrochemical Quartz Crystal microbalance is a tool that is capable of measuring nanogram-scale mass change on electrode surface. When applying alternating voltage to the quartz crystal with metal electrode formed on both sides, a resonant frequency by inverse piezoelectric effect depends on its thickness. The resonant frequency changes sensitively by mass change on its electrode surface; frequency increase with metal dissolution and decrease with metal deposition on the electrode surface. The relationship between resonant frequency and mass change is shown by Sauerbrey equation so that the mass change during metal dissolution can be measured in real time. Especially, it is effective in the case of reaction mechanism and rate studies accompanied by precipitation, volatilization, compound formation, etc. resulting in difficulties on ex-situ AA or ICP analysis. However, it should be carefully considered during EQCM experiments that temperature, viscosity, and hydraulic pressure of solution, and stress and surface roughness can affect on the resonant frequency. Application of EQCM was shown as a case study on leaching of platinum using aqueous chlorine for obtaining activation energy. A platinum electrode of quartz crystal oscillator with 1000 Å thickness exposed to solution was used as leaching sample. Electrogenerated chlorine as oxidant was purged and its concentration was controlled in hydrochloric acid solution. From the experimental results, platinum dissolution by chlorine is chemical reaction control with activation energy of 83.5 kJ/mol.

• Tunnel and Underground Space
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• v.31 no.4
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• pp.221-242
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• 2021

A numerical study of the performance assesment of coupled thermo-hydro-mechanical (THM) processes in improved Korean reference disposal system (KRS⁺) for high-level radioactive waste is conducted using TOUGH2-MP/FLAC3D simulator. Decay heat from high-level radioactive waste increases the temperature of the repository, and it decreases as decay heat is reduced. The maximum temperature of the repository is below a maximum temperature criterion of 100℃. Saturation of bentonite buffer adjacent to the canister is initially reduced due to pore water evaporation induced by temperature increase. Bentonite buffer is saturated 250 years after the disposal of high-level radioactive waste by inflow of groundwater from the surrounding rock mass. Initial saturation of rock mass decreases as groundwater in rock mass is moved to bentnonite buffer by suction, but rock mass is saturated after inflow of groundwater from the far-field area. Stress changes at rock mass are compared to the Mohr-Coulomb failure criterion and the spalling strength in order to investigate the potential rock failure by thermal stress and swelling pressure. Additional simulations are conducted with the reduced spacing of deposition holes. The maximum temperature of bentonite buffer exceeds 100℃ as deposition hole spacing is smaller than 5.5 m. However, temperature of about 56.1% volume of bentonite buffer is below 90℃. The methodology of numerical modeling used in this study can be applied to the performance assessment of coupled THM processes for high-level radioactive waste repositories with various input parameters and geological conditions such as site-specific stress models and geothermal gradients.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.3
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• pp.263-274
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• 2020

In the Southeast Sea of Korea, a cold water mass is formed intensively in summer every year, causing frequent abnormal sea conditions. In order to analyze the spatial changes of sea surface temperature distribution in this area, ocean fields buoy data observed at Gori and Jeongja and reanalyzed sea surface temperature(SST) data from GHRSST Level 4 were used from June to September 2018. The buoy data were used to analyze the time-series water temperature changes at two stations, and the GHRSST data were used to calculate the daily SST variance and weighted mean center(WMC) across the study area. When the buoy's water temperature was lowered, the variance of SST in the study area trend to increase, but it did not appear consistently for the entire period. This is because GHRSST is a reanalysis data that does not reflect sensitive changes in water temperature along the coast. As such, there is a limit to grasping the local small-scale water temperature change in the coast or detecting the location and extent of the cold water zone only by the statistical variance representing the SST change in the entire sea area. Therefore, as a result of using WMC to quantitatively determine the spatial location of the cold water mass, when the cold water zone occurred, WMC was located in the northwest sea area from the mean center(MC) of the study area. This means that it is possible to quantitatively identify where and to what extent the distribution of cold surface water temperature appears through SST's WMC location information, and we could see the possibility of WMC's use in detecting the scale of cold water zones and the extent of regional spread in the future.

• The Journal of Art Theory & Practice
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• no.6
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• pp.27-50
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• 2008

This thesis examines contemporary Chinese painting after the Cultural Revolution(1966~76), focusing upon so-called "Chinese Pop art", which I termed as "Socialist Pop art". I considered the art of this period within the broader context of social changes especially after the Tienanmen incident of 1989. After the Cultural Revolution during which idolization of Chairman Mao was at its peak, one of the major changes in communist China was that an anti-Mao wave was generated in almost every social class. For example, novels that revealed the hardships during the Cultural Revolution were published. Posters that openly criticized the Maoism were also produced and displayed on the walls, and demand for democracy spurred widespread activist movements among young generations. These broad social changes were also reflected in art. A variety of art movements were introduced from the West to China, and after a period of experimentation with the new imported styles, artists began to apply the new artistic idiom to their works in order to visualize their own social and political realities they lived in. It was a shift from earlier Socialist Realism to a new expression either directly or indirectly, "Socialist Pop", an amalgam of Socialist Realism and Pop art tradition. After the 1989 crackdown of Tienanmen Square protest, when communist government quelled with brutal measures the students, workers, and ordinary people who rose for democracy, greater urge to protest the Deng Xiaoping regime emerged. This time coincided with the gradual emergence of art using Pop art vocabulary to satirize the social reality, the Socialist Pop art, along with many other art forms all with avant-garde spirit. One of the most frequent subjects of Chinese Pop art was visual images of Chairman Mao and his Cultural Revolution, and new China that was saturated with capitalism, which tainted the Chinese way of life with a Western way of consumerism and commercialism. The reason for the popularity of Mao's image was spurred by the "Mao Craze" in the early 1990's. People suddenly began to fall in a kind of nostalgia for the past, and once again, Mao Zedong was idolized as an entity who can heal the problems of modern China who had been marching towards their ultimate destination, the economic development. But this time Chairman Mao was no more an idol but just a popular, commercial product. He is no more an object of worship of almost religious nature but he has become an iconography symbolizing the complex nature of present Chinese society. During this process of depicting the social reality, Chinese artists are making the authority and sanctity of Maoism ineffective. Dealing with this new trend of contemporary Chinese art in view of "Socialist Pop art" two manners of re-creating Pop art can be illustrated: one that incorporates the propaganda posters of the Cultural Revolution; the other borrows from Chinese traditional popular imagery or mass media, such as photos taken during Mao era. What is worth mentioning is that these posters and photos of the Cultural Revolution can be identified as 'popular' media, as they were directed to educate the popular mass, thus combination of this ingenuous pop media with Western Pop art can be fully justified as a genre unique to China. Through this genre, we can discover a new chapter of the Chinese contemporary painting and its society, as their Pop art can be considered as self-portraits true to their present appearances.

• Journal of the Korea Institute of Building Construction
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• v.9 no.6
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• pp.113-119
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• 2009

This study is to investigate the fundamental and fireproof qualities of high strength concrete corresponding to changes in the curing factors and the PP fiber ratio. The results were as follows. For the fundamental characteristics of concrete, the fluidity was reduced in proportion to the increase in the PP fiber ratio. The compressive strength was somewhat reduced according to an increase in the PP fiber ratio. However, it had the high strength scope of more than 60 MPa at 7 days and of more than 90 MPa at 28 days. On the spalling mechanism followed by changes of the water content ratio, spalling was prevented in all combinations, except the specimen without PP fiber and subjected to 3.0% of moisture contents. When spalling was prevented at that time, the residual compressive strength ratio was 22%~41% and the mass reduction ratio was 5%~7%, which was relatively favorable. As the spalling mechanism corresponds to changes in the curing method, spalling was prevented in concrete with a PP fiber mixing ratio of more than 0.05% in the event of standard curing, and in concrete with a PP fiber mixing ratio of more than 0.10% in the case of steam curing and autoclave curing. In these cases, when spalling was prevented, the residual compressive strength ratio was 23~42% and the mass reduction ratio was 7~11%. In these results, the ease of spalling prevention in high strength concrete was inversely proportional to the water content ratio. Depending on the curing method, spalling was prevented in concrete with over 0.05% PP fiber with standard curing and in concrete with over 0.1% PP fiber with steam curing and autoclave curing.

• Journal of Preventive Medicine and Public Health
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• v.26 no.3 s.43
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• pp.387-399
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• 1993

This study was conducted to analyze blood lipid profile and other risk factors among crew members who are currently active and had more than 10 years of experience as crew members. Data was analyzed using medical record files in an airline medical department. The results are as follows. 1. The total number of crew members studied was 392. Among age groups, those below age 40 consisted of 26(6.9% of the total), those in age $41{\sim}50$ were 135 (34.4%) and those over age 51 were 230 (58.7%). 263 were former air force pilots consisting 66.9%. Those who had captain status numbered 21 I comprising 53.7% of the total. The type of aircraft most of the crew members involved were large size aircraft which totaled 268 (68.2%). With respect to the number of working years as crew members, 488(48.9%) comprised the largest group with $11{\sim}15$ years. 2. The rate of smoking among crew members has shown gradual decrease with 50.3% smoking in 1983 to 33.6% in 1993. Among $41{\sim}50$ age group the rate has shown a decrease from 20.9% to 13.3% In those group over age 51 it decreased from 25.5% to 16.6%. But group below age 40 were within the range of 3.6~3.8% with no significant change in the rate of smoking. 3. Body Mass Index in age group over 51 was slightly higher than other age groups. On the whole, BMI over 25 was not found. 4. The total cholesterol levels of those below age 40 were $196.9{\pm}38.5mg/dl,\;216.2{\pm}39.2mg/dl$ in ages $41{\sim}50$, and $225.1{\pm}42.5mg/dl$ in age group over 51. No significant difference was found among age groups. 5. HDL-cholesterol levels of over age 50 were higher than other age group and ranged from $40{\sim}55mg/dl$. 6. LDL-cholesterol levels of those over 51 were $126.7{\pm}37.7mg/dl$ higher than other age groups. But there were no significant changes in all age during 10 years of follow up. 7. Cardiac index of age group below age 40 was 3.8, 4.3 in age group $41{\sim}50$ and 4.5 in those over age 51 group. No significant changes among groups were found during the follow up period. 8. Triglyceride levels of age group below age 40 was $142.2{\pm}70.1,\;167.3{\pm}77.5$ in age group of $41{\sim}50$ and $113.6{\pm}897$ in age group over 50 showing that triglyceride levels increased with age. No significant changes in pattern were noted.

• Korean Journal of Food Science and Technology
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• v.5 no.4
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• pp.231-234
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• 1973

Dried lavers, Porphyra yezoensis Ueda, were stored at $20^{\circ}C$ for 10, 25 and 45 days under a dry and humid conditions respectively, and changes in the contents of organic acids were studied by GLC and supplementary use of GC-MS. 1) Out of eight acids determined, i. e., pyruvic, lactic, oxalic, malonic, fumaric, succinic, malic, and citric acid, relatively abundant ones were oxalic, succinic, malic, and citric acid. 2) Oxalic, malic, and succinic acid did not show any notable changes in their contents under a dry condition, however, under a humid condition the contents of the former tow acids decreased rapidly showing contrast to that of succinic acid, of which content increased markedly. The content of citric acid rapidly· decreased independent of the storage conditions. 3) Among some unidentified components, two of them were presumed to be aromatic acids from their mass spectra. The contents of the two acids decreased slowly under a dry condition, however, rapidly decreased under a humid condition and after 45 days storage almost all of them disappeared. 4) The contents of total volatile acids were increased under the both storage conditions, however, the rate of increment was larger under a humid than under a dry condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6130-6141
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• 2015

This study was performed to elucidate the association of blood pressure and incidence of hypertension in response to changes in body mass index. A total of 28,249 industrial workers (male: 25,548, female: 2,701) who aged 30~69 years old, received regular medical check-up at least once per year from 2002 to 2012 (over 11 years) were included. In the analysis, the averages of blood pressure were stratified by BMI which was obtained from the initial examination results of each individual. In addition, averages of changes in blood pressure were analyzed by stratifying with changes in BMI over 10 years(from 2002); annual occurrence rates of high blood pressure, stratified per BMI, were further assessed in which patients were in normal ranges of blood pressure. As a result, the averages blood pressure over 10 years were more significantly elevating in the group of obesity compared to those of the low weight group as well as the normal weight group. Similarly, when it comes to the occurrence rates of high blood pressure, the group of higher BMI represented elevated risks compared to the groups of low BMI. In conclusion, the increase of BMI over 10 years(2002-20012) were significantly influenced on the increase of blood pressure.

• Journal of Nutrition and Health
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• v.38 no.6
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• pp.432-444
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• 2005

The purpose of this study was to investigate the effect of medical nutrition therapy (MNT) on anthropometric measurements, quality of diets, and blood parameters through the weight loss program in over weight or obese women. The subjects (n=76, $age\;31.1{\pm}8.4y,\;weight\;70.3{\pm}7.9kg,\;BMI\;27.2{\pm}2.4kg/m^2$) without medical disease were treated with MNT 5 times for 12 weeks by dietitian. Anthropometric measurements included height, weight, fat mass, lean body mass, triceps and thigh skin-fold thickness, mid-arm, waist, hip and thigh circumference. Dietary assessments were accomplished using 3-days food records, diet quality index (DQI), and dietary pattern. The dietary pattern was assessed by daily energy intakes from breakfast, lunch, dinner, and snacks of calorie density, and numbers of eating. Blood levels of leptin, lipid profiles (total lipids, total cholesterol, LDL-cholesterol, HDL-cholesterol), and insulin were analyzed. Anthropometric measurements decreased significantly after MNT (p<0.001). Waist circumference was reduced most rapidly and tricep skin-fold thickness was reduced most effectively after 12 weeks of MNT. Daily energy intake, calorie density and numbers of eating incidence decreased significantly $0796.4{\pm}395.5\;vs\;1402.9{\pm}217.8\;kcal/day,\;162.3{\pm}56.5\;vs\;113.4{\pm}30.1,\;5.0{\pm}1.4\;vs\;3.8{\pm}0.4$, respectively, p<0.05). The daily energy intake from breakfast and snacks significantly decreased (p<0.001). Calories from snack, calorie density of snack and numbers of snacking also decreased (p<0.05). The mean scores of DQI significantly increased ($7.6{\pm}2.1\;vs\;6.5{\pm}1.6$, p<0.05). The plasma levels of total lipid, triglyceride (TG), total cholesterol, LDL-cholesterol and leptin decreased significantly after MNT ($489.8{\pm}100.4\;vs\;447.0{\pm}87.3mg/dL,\;187.7{\pm}34.0\;vs\;175.9{\pm}31.5mg/dL,\;115.2{\pm}29.2\;vs\;109.2{\pm}26.7mg/dL,\;15.7{\pm}7.6\;vs\;12.4{\pm}5.9ng/mL$, respectively, p<0.05). These results indicate that MNT efficiently reduced the body weight through the changes in dietary intake, dietary patterns and dietary quality. MNT also changed body composition and reduced the levels of plasma lipid, cholesterol and leptin.