• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.8
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• pp.692-700
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• 2014

In this work, satellite FE (finite element) model updating for the prediction of the effect of micro-vibration is described. In the case of satellites launched in low earth orbit, high agility and more mission accomplishments are required by the customer in order to procure many images from satellites. To achieve the goal, many mechanisms, including high capacity wheels and antennas with multi-axis gimbals have been widely adopted, but they become a source of micro-vibration which could significantly deteriorate the quality of images. To investigate the effect due to the micro-vibration in orbit on the ground, a prediction is conducted through an integrated model coupling the measured jitter sources with FE (finite element) model. Before prediction, the FE model is updated to match simulation results with the modal survey test. Subsequently, the quality of FE model is evaluated in terms of frequency deviation error, the resemblance of mode shapes and FRFs (frequency response functions) between test and analysis.

• Korean Journal of Environmental Biology
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• v.24 no.2 s.62
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• pp.119-125
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• 2006

Present study aims to study antioxidant enzyme activity due to turbidity change in various tissues of Carassius auratus. As for the changes of antioxidant enzyme activity in tissues of C. auratus pursuant to the raising period under 50, 100, and 150 NTU with turbid water levels, there was no great difference between 50 NTU and 100 NTU compared to a control (0 NTU), however, it demonstrated a relatively noticeable difference at 150 NTU high turbid water level. When considering the antioxidant capacity in tissues of C. auratus in terms of DPPH free radical scavenging activity, there was shown a high activity in gill and liver tissues, therefore, it is thought that there appears a non-enzymatic antioxidant reaction when C. auratus is reared under the condition of highly turbid water. As for the enzymatic antioxidant reaction of antioxidant enzyme activity got increased as turbid water level went higher in order of 50, 100, 150 NTU, and the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione-s-transperase (GST), increased in all tissues except for an integument, up to 20th day when it was started to be reared, and they showed a gradual decrease as time passed by. However, since the activity of glutathione reductase (GR) and glutathione peroxidase (GPX) is very low in almost all tissues, it is thought that the role of those enzymes would be quite ignorable in the course of antioxidant process.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.22-29
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• 2012

Robot related injuries in industrial accidents statistics during 2008~2010 have accounted for a total of 109 cases equivalent to 30~40 cases for each of those years. The number of injured compared to the dissemination of industrial robots(51,302 units/2004) can be regarded as quite low. However, the fatal injuries sustained by 7 (6.4%) out of 109 cases paints the stark reality of robot-related accident fatalities. It is a sad probability that as the automation process expands its use of industrial robots which have increased significantly in demand, the incidence of workplace accidents will also increase. Therefore, the incidence of accidents throughout the period of 2008~2010 has been analysed to prevent the injuries due to the increased use of industrial robots. In the analysis, the injuries occurred during the industrial robot operation accounted for 45.9% of the entire accidents. Thus, we examined the present status of the industrial robot operation to analyze the root cause of accidents occurred in our studied time period. We looked at a total of 469 workplaces. 456 workplaces responded in the year 2009 and survey studies were implemented at 13 of the 29 workplaces where work injuries were sustained in the year 2010. Even where protective measures and interlock devices were in place, our studies indicated that workers could access the robot area to perform the tasks in 188 sites(40.1%). Also, the 143 sites(30.5%) had control measures and equipment located in the safety fence. In addition, the robots found at 164 sites(35.0%) could be restarted without additional restarting operation. These three causes accounted for most of the workplace injuries during the industrial robot operations. Futhermore, we confirmed the fact that the protective measures of the current safety regulations were not strictly enforced. Based upon our studies and the investigation of the present status of the industrial robot operation, higher standards in training and supervision of workers in the robot operation must quickly be met in order to prevent these industrial injuries.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.1
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• pp.29-35
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• 2015

The concept design of a riser for Ocean Thermal Energy Conversion in 10 MW is proposed and its dynamic behaviour characteristics is analyzed with numerical method. A riser pipe with a hollow along its thickness in the cross-section to increase the effective modulus of its cross-section is designed considering the manufacture. The riser pipe without hollows along its thickness needs a lumped weight at the bottom end of a riser in order to keep its vertical hanging configuration from large buoyancy and the strong current. The riser is designed to control its density by inserting materials in high or low density into a hollow. The dynamic behaviour characteristics of the two designed risers is evaluated with the developed numerical analysis tool. The combined stress of the riser with a lumped weight is showed to be dominated by weight of a lumped mass. The riser with no hollow shows large combined stress near sea surface by strong current. Local structural analysis for the cross-section of a hollow riser is needed in detail.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.644-653
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• 2018

Landslides occur frequently due to the effects of heavy rainfall and typhoons caused by climate change. Erosion control measures are needed to effectively prevent landslide damage. In order to improve their efficiency, it is necessary to quantitatively measure the sediment discharge from the mountain stream. In this study, a load cell sensor was installed in a mountain stream and the measured values were compared according to the applicability and load test type in the mountain stream. The result of the load test showed that the effect of the loading type (load test 1, 2) was low at average (loadings) of 0.4kgf and 0.6kgf at sites 1 and 2, respectively. The load factor was also derived by regression analysis to increase the accuracy of the measured values. According to the results of the load factor (normalized) to the load-cell measurement value, the output value increased by 14.8% and 24.6% in sites 1 and 2, respectively, and was calculated to be similar to the reference value. The load cell sensor enabled us to quantitatively estimate the amount of sediment discharge in the mountain stream through time series analysis with the water level and rainfall information. If the monitoring is carried out for a long time, it can be used to find the sediment discharge mechanism for the mountain stream. In addition, applying sensors such as load-cells to a mountain stream is expected to contribute to the development of related industries, such as the manufacturing of measurement sensors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.565-576
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• 2020

This study compares and analyzes satisfaction with Korean and Canadian primary medical care based on a survey of Koreans living in Canada. Based on data collected from Koreans who live in Canada, a paired sample t-test, analysis of variance (ANOVA), and GLM were used. The main conclusions of this study are as follows. First, overall satisfaction with Korean primary care was high. Second, the results of the analysis were stable, regardless of gender, age, education, and residential area. Third, overall satisfaction with Korean medical care was higher than for medical care in Canada. Fourth, satisfaction was high in terms of treatment skill and technology, and promptness in appointments, but was low in terms of medical expense. Fifth, there was a high level of confidence in physician skills and practices, but there was no significant difference in terms of sufficient counseling and explanations. Finally, the survey found that the tendency to increase medical treatment volume in order to increase a physician's own income was large. As a result of detailed analysis, it was concluded that Korea's primary care is more competitive than in Canada, but the primary medical doctors' patient interview and explanation obligations, and incentives to control income and medical expenses, need to be improved.

• Journal of Conservation Science
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• v.34 no.3
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• pp.211-225
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• 2018

The Stupa of the State Preceptor Jigwang from the Beopcheonsaji temple site in Wonju (National Treasure No. 101) was built in the Goryeo Period (around the 11th century), with very excellent style and techniques. It was returned to the Korea after being taken to Osaka of Japan without notice in 1912, and was severely damaged during the Korean War. Subsequently, the Stupa was restored using restoration materials like mortar, and relocated to the National Palace Museum of Korea. Surface contaminants in the Stupa primarily existed around the restoration materials. Black discoloration, which indicates a high discoloration grade, signified a high possession rate in the north and inner regions of the Stupa, which may be related to the relative moisture maintenance time. Most surface contaminants were calcite and gypsum; the black discoloration area underwent secondary discoloration due to air pollution. Moreover, the stone properties exhibited a relatively low discoloration grade, exhibiting crystallized contaminants that partly covered the rock-forming minerals. Overall, the Stupa deteriorated due to discoloration and being covered by lime materials, which were dissolved as the mortar degraded. Hence, it required contaminants removal, surface cleaning and desalination during conservation treatment, in order to control the rate of physicochemical deterioration by contaminants.

• Journal of Astronomy and Space Sciences
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• v.26 no.4
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• pp.499-510
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• 2009

In this paper, relative orbit of Low Earth Orbit satellites is determined using only GPS measurements and the effects of Equatorial Spread-F (ESF), that is one of biggest ionospheric irregularities, are investigated. First, relative orbit determiation process is constructed based on doubly differenced GPS observations. In order to see orbit determination performance, relative orbit of two GRACE satellites is estimated for one month in 2004 when no ESF is observed. The root mean square of the achieved baselines compared with that from K-Band Ranger sensor is about 2~3 mm and average of 95% of ambiguities are resolved. Based on this performance, the relative orbit is estimated for two weeks of two difference years, 2003 when there are lots of ESF occurred, and 2004 when only few ESF occurred. For 2003, the averaged baseline error over two weeks is about 15 mm. That is about 4 times larger than the case of 2004 (3.6 mm). Ionospheric status achieved from K-Band Ranging sensor also shows that more Equatorial Spread-F occurred at 2003 than 2004. Investigation on raw observations and screening process revealed that the ionospheric irregualarities caused by Equatorial Spread-F gave significant effects on GPS signal like signal loss or enhancement ionospheric error, From this study, relative orbit determination using GPS observations should consider the effect of Equatorial Spread-F and adjust orbit determination strategy, especially at the time of solar maximum.

• Journal of Nutrition and Health
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• v.45 no.3
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• pp.264-273
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• 2012

This study analyzes the food frequency for the elderly regarding different family types and finds the factors for nutritional risk, offers a basic reference for providing nutritional support for them. The study referred to the dietary behavioral survey data of 3,680 elderly people (1652 male and 2028 female) from 21 regions in the northern Kyeonggi province. The data was collected through the method of one-to-one interviews and was a part of the Community Health Survey for 2008 by the Korea Centers for Disease Control and Prevention (KCDC). We classified family types as a household for elderly people living alone, a household of elderly people with a spouse, a household of the elderly with unmarried children and a household of the elderly with married children, and as for intakes of foods, the frequencies of taking fruits, vegetables, kimchi, rice with mixed cereals, meat, fish, bean tofu soymilk, milk and dairy products, as well as sweet beverages are calculated on a daily basis and skipped meals are calculated on a weekly basis. Elderly women showed lower income, lower education level, higher unemployment rates, and a higher rate of government healthcare subsidies than elderly men. Elderly women tend to live alone and with their children while elderly men tend to live with their spouse. In both males and females, the intake of fruits and vegetables were the least in the elderly living alone, while the elderly with married children ate the most. In both males and females, the household of the elderly living alone ate significantly less amounts of Kimchi than other family types. Elderly people living alone tended to have significantly less meat and fish, especially women. In the case of rice with mixed cereals, the elderly men living alone and the elderly men with unmarried children ate significantly less amounts than the elderly men living with a spouse. The elderly men living alone took significantly less milk and dairy products than the elderly men with unmarried children while the elderly women living with a spouse took significantly less milk and dairy products than the elderly women with married children. With regards to the frequency of meal-skipping, the elderly living alone had the highest frequency for skipping meals. From this result, having various foods is difficult for the elderly living alone. Furthermore, the elderly living with unmarried children demonstrated a low quality of dietary life compared to those of married children. Hence, it can be concluded that social support is important in order for the elderly to have a balanced diet.

• Journal of Korean Society on Water Environment
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• v.21 no.5
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• pp.477-483
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• 2005

Anammox (Anaerobic Ammonium Oxidation) bacteria is recently discovered microorganism which can oxidize ammonium to nitrogen gas in the presence of nitrite under anaerobic conditions. The anammox process can save an energy for nitrification and need not require a carbon source for denitrification, however, the start-up periods takes a long time more than several months due to the long doubling time (approximately 11 days). In order to find the effects of seeding microorganisms, hydrazine, and nitrite concentration on the enhancement of the anammox activity, five kinds of microorganisms were selected. Among the several kinds of seeding microorganisms, the granule from acclimated microorganisms treating high concentration of ammonia nitrogen (A-1) and sludge from piggery wastewater treatment plant (A-2) were found to have a high anammox activity. In the case of A-1, the maximum nitrogen conversion rate represented 0.4 mg N/L-hr, and the amount of nitrite utilization was high compared to those of other seeding microorganisms. The A-4 represented a higher nitrogen conversion rate to 0.7 mg N/L-hr although the ammonium concentration in the serum bottle was high as 200 mg/L. Meanwhile, the anaerobic granule from UASB reactor treating distillery wastewater showed a low anammox activity due to the denitrification by the remained carbon sources in the granule. Hydrazine, intermediate product in anammox reaction, enhanced the anammox activity by representing 1.4 times of nitrogen gas was produced in the test bottle than that of control, when 0.4 mM of $N_2H_4$ was added to serum bottle which contains 5 mM of nitrite. The high concentration of nitrite (10 mM) resulted in the decrease of the anammox activity by showing lower production of nitrogen gas compared to that of 5 mM addition of nitrite concentration. As a result of FISH (Florescence In-Situ Hybridization) experiment, the Amx820 probe showed a more than 13% of anammox bacteria in a granule (A-1).