• The Journal of Engineering Research
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• v.1 no.1
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• pp.5-14
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• 1997

The purpose of thesis is to analyze the radiation characteristics of an offset gregorian antenna in order to design the satellite-loaded antenna. In order to compute the radiation pattern of the sub-reflector, the reflected wave is obtained by GO(Geometric Optics) at an arbitrary shaped sub-reflector. Then the total radiation EM wave is obtained by summing the diffracted fields obtained by UTD(Uniform Geometrical Theory of Diffraction) and the GO fields. In order to calculate the far field radiation pattern of the main reflector, the radiation integral equation is derived from the induced current density on reflector surface using PO(Physical Optics). The kernel is expanded in terms of Jacobi-Bessel series for increasing the computational efficiency, then the modified radiation integral is represented as the double integral equation independent of observation points. When the incident fields are assumed to be x-or y-polarized field, the characteristics of radiation patterns in the gregorian antenna is analyzed in case of the main reflector having the focal length of 62.4$\lambda$, diameter of 100$\lambda$, and offset height of 75$\lambda$, and the sub-reflector having the eccentricity of 0.501, the inter focal length og 32.8$\lambda$, the horn axis angle of $9^{\circ}$ and the half aperture angle of $15.89^{\circ}$. The cross-polarized level and side lobe level in the offset geogorian reflector are reduced by 30dB and 10dB, respectively, in comparison with those of the offset parabolic antenna.

• Korean Journal of Microbiology
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• v.34 no.4
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• pp.219-224
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• 1998

The cyclic metabolism of poly(3-hydroxyhutyrate-co-3-hydroxyvalerate) synthesized from glucose by Alcaligenes sp. SH-69 in the presence or absence of new carbon substrate was investigated. In batch culture, the content and weight average molecular weight of the copolymer already stored in the cell decreased rapidly when there was no other carbon source available. After the depletion of carbon source, the amount of high molecular weight copolymer decreased more rapidly than that of low molecular weight copolymer, and as a result, average molecular weight distribution shifted to the lower value. The addition of a mixture of glucose and levulinic acid when the initial carbon substrate, glucose, was nearly depleted supported the continual increase in cell mass and the accumulation of poly(3HB-co-3HV) with high molar fraction of 3HV. However, solvent fractionation of the polymer with acetone revealed the degradation of pre-existing polyhydroxyalkanoale (PHA) in parallel with the synthesis of PHA from new carbon substrate. Even though PHAs obtained from each substrate alone were the copolymer of 3HB and 3HV, it was found that the polymer accumulated in the cells grown by sequential feeding was mainly physical mixture of two poly(3HB-co-3HV) copolymers containing different molar fractions of 3HV.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.35 no.4
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• pp.126-133
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• 2017

This study analyzed hydrological changes of stormwater runoff of Seolleung Jeongneung zone according to the application of LID system based on landscape Architectural technology. The results are as follows. First, when flooding occurred in Gwanghwamun in July 27, 2011, the maximum instantaneous rainfall amount was 183 mm/hr recorded at 10:00 on 27th for 10 minutes, and it was confirmed that rainfall intensity more than three times as high as the maximum rainfall of 57.5 mm/hr. Second, it is possible to control peak flow rate in the case of 1,500mm of soil thickness, so that it is possible to improve the vulnerability of flood damage in Seolleung and Jeongneung zone when applying the LID system. Third, in the berm height scenario, peak flow rate control was not controled in all depth level models, but the first stormwater runoff was delayed by 4 hours and 10 minutes compared to the soil thickness scenario. It was interpreted as a relatively important indicator the soil thickness for the initial stromwater runoff reduction and the berm height for the peak runoff. Through this, the systematic adaptation of landscape-friendly ecological factors within the cultural property protection zone could theoretically confirm the effects of flood disaster prevention.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.5
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• pp.512-520
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• 2019

It is quite useful to represent speeches visually for learners who study foreign languages as well as the hearing impaired who cannot directly hear speeches, and a number of researches have been presented in the literature. They remain, however, at the level of representing the characteristics of speeches using colors or showing the changing shape of lips and mouth using the animation-based representation. As a result of such approaches, those methods cannot tell the users how far their pronunciations are away from the standard ones, and moreover they make it technically difficult to develop such a system in which users can correct their pronunciation in an interactive manner. In order to address these kind of drawbacks, this paper proposes a speech visualization model based on the relative distance between the user's speech and the standard one, furthermore suggests actual implementation directions by applying the proposed model to the visualization of Korean vowels. The method extract three formants F1, F2, and F3 from speech signals and feed them into the Kohonen's SOM to map the results into 2-D screen and represent each speech as a pint on the screen. We have presented a real system implemented using the open source formant analysis software on the speech of a Korean instructor and several foreign students studying Korean language, in which the user interface was built using the Javascript for the screen display.

• Health Policy and Management
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• v.29 no.1
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• pp.4-10
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• 2019

The term new tobacco products (NTPs) refers to the new alternatives to conventional cigarettes. There are several kinds of NTPs in South Korea. The present study discusses the most widely used NTPs namely electronic cigarette (ECs) and heated tobacco products (HTPs). The aims of this study are to evaluate the risk related to the use of ECs and HTPs, introduce policy examples across different countries of management of this issue, and finally, present some policy implications of the problem and our response strategies. Since the advent of ECs, there has been a lot of debate about its risk. Some studies have reported that ECs are less harmful than conventional cigarettes and that they are effective in aiding smoking cessation. Nevertheless, the efficacy of ECs in smoking cessation and its potential health risks are still unclear. However, the obvious fact is that it is not harmless. Regulations on ECs differ from country to country. In many countries, they are strictly regulated as tobacco or toxic substances; however, in the United Kingdom, the use of ECs are included as part of their smoking cessation policy, and in Japan, they are treated as a form of medication. On the other hand, HTPs are the most recently introduced NTPs and they have attained sensational popularity because of the wrongly held belief that they are less harmful to health. So, what about our policy response to these two tobacco products? The research on ECs requires more systematic statistical monitoring, such as monitoring the ratio of dual-users. Further, the new EC smokers should be identified taking into account that the arguments for the use of ECs often emphasize smoking cessation or less risks to health, the government should further strengthen its policy to prevent those claims. The HTPs market experienced a very sharp growth and continues to grow because the government policy is too passive. Taking this as a lesson, it is necessary to approach NTPs, such as HTPs, proactively and increase their contribution to the National Health Promotion Fund by imposing greater taxes on them. Finally, considering the likelihood of NTPs being promoted as a less harmful tobacco product, it is essential to strictly regulate tobacco companies' publicity from the very beginning to ensure that potential consumer s are not mislead.

• Journal of Digital Convergence
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• v.17 no.1
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• pp.337-345
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• 2019

In this study, it focused on observational documentary based on observation. This study comparatively analyzed how differently the narrative style is implemented depending on the social and cultural background of East and West by analyzing the narrative style of Frederick Wiseman, a representative director of observational documentary who has been active in foreign countries for a long time, and Lee Seung-jun, recently become active in Korea. As a result of the analysis, It might be too early to judge by simple comparison of two directors, but it became an opportunity to see the difference between the long-standing observer style and the observer style documentary which actively accepts the new form. While it cannot be simply judged which style is better between the traditional observer style which shapes the simple contents into conflicts in the sequence structure and the recent style which sublimates the human inner conflict into the drama, a side could have been seen that the diversity is attained. It can be judged that the traditional documentary film can be gradually changed later. It was found that the documentary can emerge from the logic that it is difficult and boring, and that the same theme can be various and creative depending on what style is chosen.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.1
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• pp.141-148
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• 2021

In some intersections or busy traffic roads, there are more pedestrians in a specific period of time, and there are many traffic accidents caused by road congestion. Especially at the intersection where there are schools nearby, it is particularly important to protect the traffic safety of students in busy hours. In the past, when designing traffic lights, the safety of pedestrians was seldom taken into account, and the identification of motor vehicles and traffic optimization were mostly studied. How to keep the road smooth as far as possible under the premise of ensuring the safety of pedestrians, especially students, will be the key research direction of this paper. This paper will focus on person, motorcycle, bicycle, car and bus recognition research. Through investigation and comparison, this paper proposes to use YOLO v4 network to identify the location and quantity of objects. YOLO v4 has the characteristics of strong ability of small target recognition, high precision and fast processing speed, and sets the data acquisition object to train and test the image set. Using the statistics of the accuracy rate, error rate and omission rate of the target in the video, the network trained in this paper can accurately and effectively identify persons, motorcycles, bicycles, cars and buses in the moving images.

• Journal of Microbiology and Biotechnology
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• v.32 no.8
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• pp.1017-1025
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• 2022

Bone homeostasis is regulated by constant remodeling through osteogenesis by osteoblasts and osteolysis by osteoclasts and osteoporosis can be provoked when this balance is broken. Present pharmaceutical treatments for osteoporosis have harmful side effects and thus, our goal was to develop therapeutics from intrisincally safe natural products. Fucoidan is a polysaccharide extracted from many species of brown seaweed, with valuable pharmaceutical activities. To intensify the effect of fucoidan on bone homeostasis, we hydrolyzed fucoidan using AMG, Pectinex and Viscozyme. Of these, fucoidan biotransformed by Pectinex (Fu/Pec) powerfully inhibited the induction of tartrate-resistant acid phosphatase (TRAP) activity in osteoclasts differentiated from bone marrow macrophages (BMMs) by the receptor for activation of nuclear factor-κB ligand (RANKL). To investigate potential of lower molecular weight fucoidan it was separated into >300 kDa, 50-300 kDa, and <50 kDa Fu/Pec fractions by ultrafiltration system. The effects of these fractions on TRAP and alkaline phosphatase (ALP) activities were then examined in differentiated osteoclasts and MC3T3-E1 osteoblasts, respectively. Interestingly, 50-300 kDa Fu/Pec suppressed RANKL-induced osteoclasts differentiation from BMMs but did not synergistically enhance osteoblasts differentiation induced by osteogenic agents. In addition, this fraction inhibited the expressions of NFATc1, TRAP, OSCAR, and RANK, which are all key transcriptional factors involved in osteoclast differentiation, and those of Src, c-Fos and Mitf, as determined by RT-PCR. In conclusion, enzymatically low-molecularized 50-300 kDa Fu/Pec suppressed TRAP by downregulating RANKL-related signaling, contributing to the inhibition of osteoclasts differentiation, and represented a potential means of inducing bone remodeling in the background of osteoporosis.

• Korean journal of aerospace and environmental medicine
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• v.31 no.1
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• pp.24-30
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• 2021

Purpose: The purpose of this study is to consider ways to strengthen it through comparison and curriculum while recognizing the importance of global competencies in liberal arts education in universities. Methods: In order to explore ways to reinforce the sub-competence of global competencies, this study was conducted at a four-year university in Chungcheong-do for one year in 2019, such as 'Global Culture Talk', 'Global Travel', 'Global Nanta', and 'Making Global Friends'. Cases of comparison and application of educational programs were analyzed. The program was attended by the Department of Business Administration, Department of Aviation Service, Department of Design, Department of Manga Animation, Department of Broadcasting and Film, and foreign exchange students. The competency-centered curriculum not only has clear educational goals, but is also very advantageous in establishing a feedback system by measuring its performance. This study will assess the effectiveness of the education plan by diagnosing the change in competencies before and after the comparison and curriculum is operated. Results: The overall global competency has increased by 0.2 points compared to 2017. By subsector, it was found that the flexibility increased by 1.4 points. In the field of cross-cultural understanding, it rose 0.6 points, and in the field of global understanding, it rose 2.2 points, showing the largest increase in the sub-fields. Nevertheless, the field of global interest remains at a low level. This is considerably low compared to flexibility and ability to understand other cultures, and it is expected that measures for improvement should be continuously sought. Since the understanding of other cultures has already exceeded 60 points, it is expected that the global competency of the university will be strengthened if the level is consistently maintained and the emphasis is placed on enhancing flexibility and improving global understanding. Conclusion: The importance of strengthening global capabilities is steadily rising. Universities are also reorganizing the curriculum by analyzing the needs and satisfaction of education consumers to respond to this. The programs operated and analyzed in this study were also made as part of this effort. However, since there are various factors that affect global competency, it cannot be but admitted that it is not easy to gauge the change in competency with only a few programs and short-term efforts. However, if the efforts pursued by this study are accumulated and supplemented through feedback from a long-term perspective, it can be expected that there are not a lot of contributions to strengthening global competencies in liberal arts education.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.5
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• pp.167-173
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• 2023

Li₃V₂(PO₄)₃ and Li₃V₂(PO₄)₃/C composite with single phase monoclinic structure for the cathode materials are successfully synthesized by direct co-precipitation method using N₂H₄·H₂O as the reducing agent and alginic acid as the carbon source, and their electrochemical properties were compared. The particles with approximately 1~2 ㎛ size and the uniform spherical-like morphology of the narrow particle size distribution were obtained. In addition, the residual carbon can also improve the electrical conductivity. The Li₃V₂(PO₄)₃/C composite has improved initial specific discharge capacity and excellent cycle characteristics to maintain capacity stably than Li₃V₂(PO₄)₃. The results indicate that the reducing agent and carbon composite can affect the good crystallinity and electrochemical performance of the cathode materials.