• Journal of the Korean Society of Radiology
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• v.13 no.3
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• pp.333-338
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• 2019

In the field of radiotherapy, the Quality Assurance(QA) procedure to verify the safety of treatment is considered to be very important. However, due to various problems of the conventional dosimeters used for the QA, researches on these dosimeters have been actively carried out to replace them. In this study, to maximize the sensitivity by visible light(VL) emitted from phosphors, blended hybrid sensors were fabricated by blending various weight percent(wt%) of $Gd_2O_2S:Tb$ which is a phosphor with excellent fluorescence efficiency into $PbI_2$. Then, the electrical properties to high energy radiation from the blended sensors and the pure $PbI_2$ sensor were compared and evaluated. As a result of the sensitivity evaluation, the sensor of 3wt% showed the highest value with more than 40% difference from the other sensors, and gradual decreasing in sensitivity was observed with increasing wt% except for the sensor of 3wt%. Also, in the reproducibility evaluation, the pure $PbI_2$ sensor exhibited a large variation in coefficient of variation(CV)>0.015, while all the blended sensors showed CV<0.015.

• Journal of the Korean Society of Radiology
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• v.13 no.1
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• pp.39-44
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• 2019

Radiation safety management is being considered very important since radioactive isotopes such as Co-60 and Ir-192 are widely used in fields such as non-destructive test(NDT). In this study, the applicability of Mercury(II) Iodide($HgI_2$) source for tracing system was evaluated. To make sure the unit cell sensor's reliability, we evaluated the electrical properties of the sensor made with $HgI_2$, and then position dependence of the sensor was analyzed and compared with the dose distribution from the planning system. As a result of the evaluation, high reliability of the sensor was shown through the linearity of R-sq > 0.990 and reproducibility of CV < 0.015. In the position dependence evaluation, the maximum value was measured at the isocenter of the sensor and gradually decreased according to the distance. However, the dose distribution data from the planning system was turned out that has difference with that of the sensor up to 30%. This seems to come from the difference between single-point measuring based planning system and area measuring based sensor.

• Journal of Practical Engineering Education
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• v.10 no.1
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• pp.73-79
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• 2018

The purpose of this study is to explore the supporting scenario to promote vocational training in North Korea in terms of cooperation level. To this end, we have embarked on a regional and industry based vocational training program by predicting the political and social situation of North Korea and staging three scenarios systematically. These scenarios were designed originally based on the Futures Group methodology. The first scenario is to establish a technical training center in one area, focusing on the electrical, electronics, and clothing sectors. The second scenario is to set up a pilot campus of vocational training college in one region by selecting the electric, electronic, and automobile industries as its main industries. The third scenario is to establish five vocational training college campuses in North Korea, focusing on electricity and electronics, IT manufacturing, telecommunications, heavy industry, and women-specialized industries. We suggested the followings: First, establishing goals and strategies for North Korean vocational training and establishing road maps. Second, the North Korean vocational training governance system needs to be established. Third, R & D infrastructure for vocational training needs to be established. Fourth, HRD and HRM system in North Korea vocational training field needs to be established. In addition, the role of public and private employment services centers to provide them should be strengthening.

• Journal of the Korean Society of Mineral and Energy Resources Engineers
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• v.55 no.6
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• pp.576-587
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• 2018

This study has focused on analysis factors affecting safety monitoring system at tailings sites, and the evaluation equipment to monitor the factors. Twenty sites at eighteen mines with unsafe conditions were selected to examine the equipment. There were three main factors influenced safety in the sites including surface erosion, piping, and slope instability. In detail, the surface erosion was divided into three sub-factors (planting, soil-topping layer, and tailings), piping into three sub-factors (liner, rain protection facility and leachate), and slop instability was also divided into three sub-factors (slop, concrete wall, and reinforcing wall). As results of in-field measurement, a CCTV was the most effective facility, and electrical resistivity survey, acoustic sensing, thermal liner sensor, structure inclinometer, rainfall meter, and flowmeter were also highly effective. According to applications of the facilities in the unstable tailings, structural defects were mainly found in the piping, which was the most important monitoring factor for safety management of tailings sites.

• The Journal of the Korea Contents Association
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• v.21 no.2
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• pp.85-99
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• 2021

Graphene, called the "dream material" is drawing attention as a groundbreaking new material that will lead the era of the 4th Industrial Revolution. Graphene has high strength, excellent electrical and thermal conductivity, excellent optical permeability, and excellent gas barrier properties. In this paper, as the South Korean government recently announced Green New Deal and Digital New Deal policy, we analyze graphene technology, which is also attracting attention for its application to Corona 19 biosensor, to understand its national R&D trend and knowledge structure, and to explore the possibility of its application. Firstly, 4,054 cases of national R&D project information for the last 10 years are collected from the National Science & Technology Information Service(NTIS) to analyze the trend of graphene-related R&D. Besides, projects classified as green technology are analyzed concerning the government's Green New Deal policy. Secondly, text mining analysis is conducted by collecting 500 recent graphene-related articles from e-newspapers. According to the analysis, the field with the largest number of projects was found to be high-efficiency secondary battery technology, and the proportion of total research funds was also the highest. It is expected that South Korea will lead the development of graphene technology in the future to become a world leader in diverse industries including electric vehicles, cellular phone batteries, next-generation semiconductors, 5G, and biosensors.

• Journal of the Korea Organic Resources Recycling Association
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• v.30 no.4
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• pp.151-163
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• 2022

This study was conducted to promote organic fertilizer(s) that sustain soil productivity for corn production and protect the environment as required by the Act on the promotion of eco-friendly agriculture. It was conducted at the research station of the Organic Agriculture Division of the National Institute of Agricultural. The treatments consisted of Compost (Com), Bokashi as fermented organic fertilizer (FOF), and mixed expeller pressed cake (PC). They were applied at 174 kg N /ha to field corn, together with a 'no fertilizer' check in Randomized Complete Block Design. At eight weeks after transplanting (WAT) corn, compost increased soil carbon (C) and nitrogen (N) to 7.48 and 0.76 g/kg respectively, while other fertilizers maintained the initial levels (before treatment application). At corn harvest (13 WAT), soil chemical properties (total C, total N, pH, electrical conductivity, P₂O₅, Ca, K, and Mg) were similar among all organic fertilizer treatments. For soil respiration, FOF increased soil CO₂ respiration by 31-76% above other fertilizer treatments. However, there were no prominent changes in the trends of CH₄ fluxes following the two mechanical weeding operations. Fermented organic fertilizer affected N₂O emissions between 87-96% lower than other fertilizer treatments. Compared to the initial microbial densities, FOF increased fungi and actinomycete colony foming unit by 25 and 16% at harvest. Therefore, the additional potential of improving soil biological fertility and local availability of raw materials make FOF a better option to sustain soil productivity while protecting the environment.

• New Physics: Sae Mulli
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• v.68 no.11
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• pp.1192-1195
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• 2018

We studied the electrical properties of organic thin-film transistors (OTFTs) fabricated at different deposition rates by measuring the field-effect mobility and the threshold voltages. As the active layer, pentacene thin film with a thickness of 50 nm was deposited at a rate of $0.05{\AA}/s$ to $1.14{\AA}/s$. The thickness of the drain-source gold electrode was 50 nm. The mobility was $1.9{\times}10^{-1}cm^2/V{\cdot}s$ at a deposition rate of $0.05{\AA}/s$, the mobility increased to $5.2{\times}10^{-1}cm^2/V{\cdot}s$ when the deposition rate was increased to $0.4{\AA}/s$, and then the mobility decreased to $6.5{\times}10^{-1}cm^2/V{\cdot}s$ when the deposition rate decreased to $1.14{\AA}/s$. Thus, the mobility of pentacene OTFTs was observed to depend on the thermal deposition rate.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.97-105
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• 2020

Recently, as the data speed and operating frequencies of Ethernet keeps increasing, electro magnetic interference (EMI) also becomes increasing. The generation of such EMI will cause malfunction of near electronic devices. In this study, EMI filters were applied to reduce the EMI generated by DC-DC SMPS (switching mode power supply), which is the main cause of EMI generation of Ethernet switch. As the EMI filter, MLCCs with excellent withstanding voltage characteristics were used, which had advantages in miniaturization and mass production. Two types of EMI MLCC filters were used, which are X-capacitor and X, Y-capacitor. X-capacitor was composed of 2 MLCCs with 10 nF and 100 nF capacity and 1 Mylar capacitor. Y-capacitor was consisted of 6 MLCCs with a capacity of 27 nF. When only X-capacitor was applied as EMI filter, the conductive EMI field strength exceeded the allowable limit in frequency range of 150 kHz ~ 30 MHz. The radiative EMI also showed high EMI strength and very small allowable margin at the specific frequencies. When the X and Y-capacitors were applied, the conductive EMI was greatly reduced, and the radiation EMI was also found to have sufficient margin. In addition, X, Y-capacitors showed very high insulation resistance and withstanding resistance performances. In conclusion, EMI X, Y-capacitors using MLCCs reduced the EMI noise effectively and showed excellent electrical reliability.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.3
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• pp.123-128
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• 2021

For accurate speed and current control in industrial applications, SRM (Switched Reluctance Motor) is very important to synchronize the stator phase excitation and rotor position in the drive due to its nature. In general, position sensors such as encoder and resolver are used to generate rotational force by exciting the stator winding according to the rotor position and to control the motor by using speed and position information. However, for these sensors, 1) the cost of the sensors is quite large in terms of price, so the proportion of the motor system to the total system cost is high. 2) In terms of mechanical, position sensors such as encoders and resolvers are attached to the stator to increase the size and weight. In conclusion, in order to drive the SRM, control based on the rotor position information should be basically performed, and it is important to design the SRM driving system according to the environment in consideration of the application field. Therefore, in this paper, we intend to study the driving and control characteristics of SRM through variable switching duty control by designing a low-cost analog driving device, deviating from the general control system using the conventional encoder and resolver.

• Korean Journal of Environmental Agriculture
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• v.40 no.1
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• pp.49-59
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• 2021

BACKGROUND: Soil salinity causes reduction of crop productivity. Rhizosphere microbes have metabolic capabilities and ability to adaptation of plants to biotic and abiotic stresses. Plant growth-promoting bacteria (PGPB) could play a role as elicitors for inducing tolerance to stresses in plants by affecting resident microorganism in soil. This study was conducted to demonstrate the effect of selected strains on rhizosphere microbial community under salinity stress. METHODS AND RESULTS: The experiments were conducted in tomato plants in pots containing field soil. Bacterial suspension was inoculated into three-week-old tomato plants, one week after inoculation, and -1,000 kPa-balanced salinity stress was imposed. The physiological and biochemical attributes of plant under salt stress were monitored by evaluating pigment, malondialdehyde (MDA), proline, soil pH, electrical conductivity (EC) and ion concentrations. To demonstrate the effect of selected Bacillus strains on rhizosphere microbial community, soil microbial diversity and abundance were evaluated with Illumina MiSeq sequencing, and primer sets of 341F/805R and ITS3/ITS4 were used for bacterial and fungal communities, respectively. As a result, when the bacterial strains were inoculated and then salinity stress was imposed, the inoculation decreases the stress susceptibility including reduction in lipid peroxidation, enhanced pigmentation and proline accumulation which subsequently resulted in better plant growth. However, bacterial inoculations did not affect diversity (observed OTUs, ACE, Chao1 and Shannon) and structure (principle coordinate analysis) of microbial communities under salinity stress. Furthermore, relative abundance in microbial communities had no significant difference between bacterial treated- and untreated-soils under salinity stress. CONCLUSION: Inoculation of Bacillus strains could affect plant responses and soil pH of tomato plants under salinity stress, whereas microbial diversity and abundance had no significant difference by the bacterial treatments. These findings demonstrated that Bacillus strains could alleviate plant's salinity damages by regulating pigments, proline, and MDA contents without significant changes of microbial community in tomato plants, and can be used as effective biostimulators against salinity stress for sustainable agriculture.