• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1655-1662
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• 2018

This paper studies the magnetic fields between the power lines which are finite length and other ones which are infinitely long around the first tower in the proximity of the power transformers. They will be used as a source of disturbance applied to the power line. The method applied in this study was gradual; develop the theoretical formulation of the magnetic fields of these lines which are finite length and other ones which are infinitely long, examine the effects of different couplings between the different neighboring lines and the distribution transformers on behavior of magnetic fields. The method also focused on the experimental results analyzing the magnetic fields which will be used as a source applied to the auditory implants EMC. The theoretical and experimental results were compared and discussed for three power lines (90kV, 150kV and 225kV) near the power station, and it proved the effect of these substations on the simulated and measured results of the magnetic field. The maximum intensities of magnetic fields measured at the height of 1m from the ground for the circuit of three lines close to each substation were significantly lower than the ICNIRP reference levels for occupational and non occupational exposures.

• Journal of the Korea Society of Computer and Information
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• v.14 no.5
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• pp.141-148
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• 2009

Wireless Sensor Networks (WSN) can be applied to various industry fields and environment analysis fields with the progress of various sensor technologies. Also WSN help automatically monitoring of sensor nodes installed at wide area. Especially, the tiny sensor nodes recently developed for the environment analysis require much more electronic power. The reasons are the measurable fields are departmentalized and the more detailed measuring fields are created by the development of various materials and applications. Furthermore, the sensor nodes operated by small batteries for the fields require low cost and low power consumption in wireless networks technology. The power efficiency is the most important factor for the WSN life time. Because the sensor nodes are installed at wide area and hard to recover. This paper proposes the WSN algorithm is applied sensor node that has low power consumption and efficiency measurement.

• Journal of the Korean Society of Combustion
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• v.21 no.3
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• pp.1-6
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• 2016

The effect of applied electric fields on jet flow instability was investigated experimentally by varying the direct current (DC) voltage and the alternating current (AC) frequency and voltage applied to a jet nozzle. We aimed to elucidate the origin of the occurrence of twin-lifted jet flames in laminar jet flow configuration, which occur when AC electric fields are applied. The results indicate that a twin-lifted jet flames originates from cold jet instability, caused by interactions between negative ions in the jet flow via electron attachment as $O_2+e{\rightarrow}O_2{^-}$ when AC electric fields are applied. This was confirmed by experiments in which a variety of gaseous jets were ejected from a nozzle to which DC voltages and AC frequencies and voltages were applied, with ambient air between two deflection plates connected to a DC power source. Experiments in which jet flows of several gases were ejected from a nozzle and AC electric fields were applied in coflow-nitrogen provided further evidence. The flow instability occurred only for oxygen and air jets. Additionally, jet instability occurred when the applied frequency was less than 80 Hz, corresponding to the characteristic collision response time. The effect of AC electric fields on the overall structure of the jet flows is also reported. Based on these results, we propose a mechanism to reduce jet flow instability when AC electric fields are applied to the nozzle.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.5
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• pp.19-26
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• 2013

This study was carried out to provide preliminary data for increasing biodiversity in agricultural ecosystem and investigate availability of using Tubificidae spp. for environment-friendly agriculture through the survey of growth of Tubificidae spp. in flooded paddy fields during winter. We estimated the number of Tubificidae spp. in rice paddy where had been flooded during the previous winter in Ganghwa-gun, Suwon-si, and Hwaseong-si (Bongdam-eup and Paltan-myeon) between March and April from 2010 to 2012. During growing period of rice, the number of Tubificidae spp. was compared between flooded and non-flooded paddy field in Ganghwa-gun. As results, mean density of Tubificidae spp. in winter flooded paddy field was 7,235.5 $ind./m^2$ in Ganghwa-gun, 14,347.5 $ind./m^2$ in Suwon-si, 59,989.9 $ind./m^2$ in Bongdam-eup, and 2,610.6 $ind./m^2$ in Paltan-myeon. Mean density of Tubificidae spp. was the highest in flooded paddy fields of Bongdam-eup that was kept wet until rice harvest time and had shallow water. While mean density was the lowest in Paltan-myeon where had deep water and later flooded paddy field than others. In Ganghwa-gun, during growing period of rice, mean density of Tubificidae spp. in flooded paddy fields (171,109.0 $ind./m^2$) and flooded fallow paddy fields (321,084.2 $ind./m^2$) was much higher than non-flooded paddy fields (1,006.6 $ind./m^2$). Flooded paddy field during winter can help increase the number of Tubificidae spp. which can control weeds and enhance biodiversity in paddy fields for environment-friendly agriculture. Early flooding and shallow water of paddy fields could be a good agriculture practice to encourage the growth of Tubificidae spp..

• Korean Journal of Food Science and Technology
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• v.47 no.1
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• pp.87-94
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• 2015

High voltage pulsed electric fields (PEF) treatment is one of the more promising nonthermal technologies to fully or partially replace thermal processing. The objective of this research was to investigate the microbial inactivation mechanisms of PEF treatment in terms of intra- and extracellular changes in the cells. Saccharomyces cerevisae cells treated with PEF showed cellular membrane damage. This resulted in the leakage of UV-absorbing materials and intracelluar ions, which increased with increasing treatment time and electric fields strength. This indicates that PEF treatment causes cell death via membrane damage and physical rupture of cell walls. We further confirmed this by Phloxine B staining, a dye that accumulates in dead cells. Using scanning and transmission electron microscopy, we observed morphological changes as well as disrupted cytoplasmic membranes in PEF treated S. cerevisae cells. In addition, PEF treatment led to damaged chromosomal DNA in S. cerevisiae.

• Informatization Policy
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• v.22 no.3
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• pp.3-15
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• 2015

This study aims to examine the recent trend of domestic researches on the Internet of Things(IoT) which has drawn a lot of attention in the field of ICT. This meta-analysis analyzes 101 studies published in academic journals from 2010, focusing on research topics, methods and the fields of study. The results show that the research topics of most used studies were related to the technological and industrial issues, and especially in the technical field, the major topic was suggesting new IoT technology. The most research method was testing research followed by the literature review. Even though engineers are holding the mainstream of the IoT technology, some experts in the field of social science release their articles nowadays. These results indicate that the IoT has a great ripple effect both technologically and socioculturally, and researches need to be vitalized in the fields of industry, service, policy and institution as well as technological fields. In addition, the research for the future should extend methodological diversity and take more convergence approaches in a variety of fields.

• Wind and Structures
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• v.30 no.2
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• pp.165-180
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• 2020

To determine tornadic wind loads, the wind pressure, forces and moments induced by tornadoes on civil structures have been studied. However, in most previous studies, only the individual building of interest was included in the wind field, which may be suitable to simulate the case where a tornado strikes rural areas. The statistical data has indicated that tornadoes induce more significant fatalities and property loss when they attack densely populated areas. To simulate this case, all buildings in the community of interest should be included in the wind field. However, this has been rarely studied. To bridge this research gap, this study will systematically investigate the influence of a community of buildings on tornadic wind fields by modeling all buildings in the community into the wind field (designated as "the Community case under tornadic winds"). For comparison, the case in which only a single building is included in the tornadic wind field (designated as "the Single-building case under tornadic winds") and the case where a community of buildings are included in the equivalent straight-line wind field (designated as "the Community case under straight-line winds") are also simulated. The results demonstrate that the presence of a number of buildings completely destroys the pattern of regular circular strips in the distribution of tangential velocity and pressure on horizontal planes. Above the roof height, the maximum tangential velocity is lower in the Community case under tornadic winds than that in the Single-building case under tornadic winds because of the higher surface friction in the Community case; below the roof height, greater tangential velocity and pressure are observed in the Community case under tornadic wind fields, and more unfavorable conditions are observed in the Community case under tornadic winds than under the equivalent straight-line winds.

• Journal of Korean Society of Rural Planning
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• v.6 no.2 s.12
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• pp.3-11
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• 2000

The high salt concentration of reclaimed tidelands in the beginning of reclamation interferes with the growth of most crops. Although the crops are cultivated in the unripened tidal reclaimed paddy fields after desalinization to be arable, they we apt to be injured from salt by the resalinization through accumulated salts in the root zone during the growing period. In oder to make the reasonable irrigation plan in the unripened tidal reclaimed paddy fields, the preventive water requirements of resalinization as well as leaching requirements have to be included in irrigation water requirements. The critical salinity for the normal growth of crops should be determined to estimate the preventive water requirements of resalinization, and the changes of salinity in soil and water should be analyzed during the growing period, In this study, the growth tests of crops were conducted by soil textures and water management methods in the experimental field with lysimeters, using the samples of good drainage soils and poor drainage soils. And the changes of salinity in soil and water during the growing period, were analyzed to obtain the basic data for determining the critical salinity and making the estimation criteria of the preventive water requirements of resalinization. As the results obtained from analyzing the changes of salinity during the growing period in the unripened tidal reclaimed paddy fields, the exchanging interval of water for the prevention of resalinization was estimated to be within two weeks in good drainage soils and a week in poor drainage soils. And the total exchanging requirements of water for the prevention of resalinization during the growing period was estimated to be over 280mm in good drainage soils and 540mm in poor drainage soils.

• Proceedings of the Korean Nuclear Society Conference
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• 2005.10a
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• pp.1043-1044
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• 2005

• Journal of radiological science and technology
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• v.5 no.1
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• pp.77-95
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• 1982

The result of this study from surveying and analyzing the present situation of educational institutes of radiologic technology, educational situation of radiologic technology, and students' attitude and recognition about the education of radiologic technology, the faculty's thought of it throughout the country from October, 1981 to April, 1982 is as follows: 1. The total number of educational institutes for radiologic technology is 11, but all of them are private colleges classified by foundation and 1,414 freshmen were admitted to enter the colleges by admission quotas of students at present in March, 1982. 2. The number of male(1965-1982) is 3,046(78.0%), that of female is 856(22.0%), and total of them is 3,904 that graduated from the departments of radiologic technology in 9 junior colleges in Korea. 3. The number of the instructional staffs in radiologic technology in Korea is 32, but among them 1 professor, 1 associate professor, 16 assistant professors and 14 full-time instructors. 4. The credits for graduation are 80-96 credits and students need required liberal arts and required major studies to get the qualification for graduation. 5. In the national examination for radio-technologist license, total 7,150 persons took the examination, but only 2,796 persons passed it, therefore, the average passed rate is 39.1% from the year 1965 to 1982. 6. 61.3% of students expressed dissatisfaction about their campus lives, the reason of which is mainly poor educational facilities(26.7%), insufficient number of faculty(21.2%) and negative Recognition on junior college from society, etc. 7. About the education of their major studies of colleges, 70.9% of students answered that they were short of laboratory works and clinical trainings rather than theoretical lessons. 8. The chief problem in practice works is about facilities and equipemtns for practice (students 39.1%, faculty 68.8%), and about the fact that too many students usually work at a time(students 17.1%, faculty 21.9%), etc. 9. 87.4% of students and 93.8% of faculty answered that clinical training in school is necessary. 10. Students' viewpoints on the radiologic technologist and the attitudes on the profession as a radiologic technologist are approximately affirmative. 11. Fields of employment to advance after graduation are mainly the fields related to their major studies(hospital, clinic, health clinic, industrial companies related and military officers of medical technology, etc.), which fields arc predominant to 74.5% rather than non-related fields(enrols into 4 year colleges, etc.). 12. 85.2% of students, 87.5% of the faculty expressed their opinions that the present academic years of 2 should be lengthened more. 13. 90.7% of the faculty expressed their opinions that the present students quotas should be reduced in whole or in part.