• KIPS Transactions on Computer and Communication Systems
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• v.12 no.10
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• pp.299-308
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• 2023

As the spectrum shortage problem has accelerated by the emergence of various services, New Radio-Unlicensed (NR-U) has appeared, allowing users who communicated in licensed bands to communicate in unlicensed bands. However, NR-U network users reduce the performance of Wi-Fi network users who communicate in the same unlicensed band. In this paper, we aim to simultaneously maximize the fairness and throughput of the unlicensed band, where the NR-U network users and the WiFi network users coexist. First, we propose an optimal power allocation scheme based on Monte Carlo Policy Gradient of reinforcement learning to maximize the sum of rates of NR-U networks utilizing rate-splitting multiple access in unlicensed bands. Then, we propose a channel occupancy time division algorithm based on sequential Raiffa bargaining solution of game theory that can simultaneously maximize system throughput and fairness for the coexistence of NR-U and WiFi networks in the same unlicensed band. Simulation results show that the rate splitting multiple access shows better performance than the conventional multiple access technology by comparing the sum-rate when the result value is finally converged under the same transmission power. In addition, we compare the data transfer amount and fairness of NR-U network users, WiFi network users, and total system, and prove that the channel occupancy time division algorithm based on sequential Raiffa bargaining solution of this paper satisfies throughput and fairness at the same time than other algorithms.

• Journal of Adhesion and Interface
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• v.13 no.1
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• pp.45-50
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• 2012

Recently developed polyketone fiber has various applications in the mechanical rubber goods as reinforcement because of its good mechanical properties. However, its surface is not suitable for good adhesion with the rubber matrix. Thus, a surface modification is essential to obtain the good interfacial adhesion. Plasma treatment, in this study, has been conducted to modify the surface of the polyketone fiber. The morphological changes of the fibers by oxygen plasma treatment were observed by using SEM and AFM. The chemical composition changes of PK fiber surface treated with oxygen plasma were investigated using an XPS (X-ray photoelectron spectroscopy). Finally, the effect of these changes on the interfacial adhesion between fiber and rubber was analyzed by using a microdroplet debonding test. By the plasma treatment, oxygen moieties on the fiber surface increased with processing time and power. The surface RMS roughness increases until the proper processing condition, but a long plasma processing time resulted in a rather reduced roughness because of surface degradation. When the treatment time and power were 60 s and 80 W, respectively, the highest interfacial shear strength (IFSS) was obtained between the PK fiber and natural rubber. However, as the treatment time and power were higher than 60 s and 80 W, respectively, the IFSS decreased because of degradation of the PK fiber surface by severe plasma treatment.

• Journal of the Society of Disaster Information
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• v.14 no.2
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• pp.174-181
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• 2018

Purpose: The purpose of this study is to develop and demonstrate the customized modernization technology of the old aged hydropower generation system in operation Method: The modernization design was carried out based on the daily, weekly, monthly, and yearly information of the power plant in operation at the site. Results: In this paper, a safety diagnosis of existing facilities located in the Philippiness was carried out in accordance with the Special Act on the Safety Management of Domestic Facilities, and a method for reinforcing the facilities was selected. Conclusion: The selection of wheel suitable for the local environment and the maintenance of the old facilities were designed by domestic repair/reinforcement technology.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.623-646
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• 2021

As the demand for electric power increases with acceleration of electrification at home and abroad, the needs for coal-fired electrical power plant are accordingly increased. However, these coal-fired electrical power plants induce also many environmental problems such as increase of air pollutants, increase of possibility of land contamination by reclamation of coal ash, even though these power plants have a good economical efficiency. In case of a by-product of coal-fired electrical power plants, only 70% of them are recycled and the remaining 30% of by-product are fully buried in surrounding ground. Consequently, this study deals with coal ash backfilling mechanism in abandoned mine openings for the purposes of increasing the coal ash recycling rate as well as securing the mine area stability. In order to analyze the backfill and ground reinforcement by interaction between rock mass and backfills, the copying samples of discontinuous surface with different roughnesses were produced for bond strength tests and direct shear tests. And statistical analysis was also conducted to decide the characteristics of bond and shear behavior with joint roughness and their curing day. Numerical simulations were also analyzed for examining the effect of interface behavior on ground stability.

• Corrosion Science and Technology
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• v.4 no.2
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• pp.56-59
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• 2005

In rebar concrete structure, the corrosion of rebar can arise the deterioration of concrete structure and may affect the safety of the whole system. Recently, several methods for corrosion protection have been used and are more important for concrete structure using the sand including chloride ion. Among several protections, electrical cathodic protection has been expected to be one of the most useful methods in corrosion protection for reinforcement of concrete structures. The anode for cathodic protection needs high current density, high corrosion resistance and low overvoltage. To fill up the special qualities, the insoluble anodes were developed and these anodes were coated with metal oxide of $TiO_2$, $ZrO_2$, $RuO_2$, and $IrO_2$. Lifetime of these anodes can be one of the important factors affecting the lifetime of concrete structure in cathodic protection. In this work, several anodes were made by sol-gel method and thermal decomposition method and the lifetime of these anodes was evaluated by NACE international standard test method, TM 0294-94. Also, we did analyze the properties of coated metal oxides.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.7
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• pp.496-501
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• 2018

In this study, we prepared 40, 45, 50, 55, 60, 65, and 70 wt% content composites filled in epoxy matrix for two micro silica and three micro alumina types for use as a GIS heavy electric machine. As a filler type of epoxy composite, micro silica composites showed excellent AC breakdown strength properties compared to micro alumina composites in the case of electrical properties of micro silica and alumina. The electrical breakdown properties of micro silica composites increased with increasing filler content, whereas those of micro alumina decreased with increasing filler content. In the case of mechanical properties, the micro silica composite showed improved tensile strength and flexural strength compared with the micro alumina composite. In addition, mechanical properties such as tensile strength and flexural strength of micro silica and alumina composites decreased with increasing filler content. This is probably because O-H groups are present on the surface of silica in the case of micro silica but are not present on the surface of alumina in the case of micro alumina.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.276-278
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• 2005

For over 25 years, the stray currents from DC electric railroads have caused serious interference problems with underground metallic infrastructures in Korea. The most serious interference is reported at the pipelines near the depot areas. Our field survey proves that this phenomena is mainly due to the missing of dedicated rectifiers for mainline, depot and/or workshop areas. Because it takes so much time and costs too much to replace the traction power system, we consider a stray current confinement method which collects the stray currents and drains them to the negative terminal of the rectifier. This can be realized by installing a stray current collecting wire along the depot boundary. Moreover, we found the stray current collecting reinforcement bar located beneath the rails of concrete slab tracks. Using this bar, we arc going to draing the stray currents from mainline rails. In this paper we show the result of field survey on railroad facilities and present the stray current confinement method under field test.

• International Commerce and Information Review
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• v.14 no.1
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• pp.301-314
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• 2012

To improve support for damages due to FTA and competitive power to overcome it, direct damages to farming and fisheries are compensated through Direct Payment Policy and Business Cessation Support System. Support plans will be developed to enhance competitive power in industries and income base in rural areas. This study carried an AHP to decide Priority and Evaluation Criteria in respect to domestic support measures according to FTA. For the AHP, the classes were categorized into direct damage conservation, higher competitive power and expansion of income. For the direct damage preservation measures, the classes were categorized into farmers, fishermen, manufactures, service business managers, and workers. In respect to reinforcement of competitive power of each industry, the classes were categorized into farming, fisheries, manufacturing, the drug industry, and service business. In respect to expansion of income, the classes were categorized into farming and fishing. Then 27 national support measures were presented for sub-classes. As a result of the analysis, it was discovered that more weight was given to measures to reinforce competitive power of each industry and expand income than those on direct damage conservation. In respect to higher competitive power in industries, more weight was given to support for farming and manufacturing. In respect to expansion of income, more weight was given on measures on farming than fisheries. For the direct damage preservation measures, more weight was given on support measures on farmers and workers.

• International Commerce and Information Review
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• v.1 no.2
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• pp.1-24
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• 1999

In this study, I have suggested a basic theories in introducing and applying EC indispensible for a positive development of international logistics' competitiveness by the Chonbuk firms, and I assure that the Chonbuk firms can get a full effect in strengthening international competitiveness in worldwide trade war by effectively utilizing the application method suggested in this study as well as by erecting its basic direction. Our market faced an accelerating pressure against a full-scale market opening with the WTO system, and our Chonbuk firms will face a danger that all the markets, domestic and international will be occupied by the foreign enterprises, for we can not win the competition with the foreign enterprises, provided that we do not prepare for the rationalization and effectiveness of management. It will be very significant for our Chonbuk firms to introduce and utilize EC as a method for innovation and rationalization of management as well as a method for strengthening international competitiveness. This study will serve the study of this field, for the purpose of this study is on analyzing its propriety in introducing and utilizing EC. It will guarantee the importance that this study helps the Chonbuk firms to upgrade understanding on introduction and utilization of EC for strengthening their logistics competitiveness, and this study serves to improve international competitiveness in an era of information and globalization.

• Cross-Cultural Studies
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• v.42
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• pp.313-342
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• 2016

This paper is an attempt to look up the life of Guanyu who was a sainted warrior of Shu Han(蜀漢) and later, was revered as God, especially focusing on the Political perspective of Chinese Dynasty. People represented Guanyu as the general during the Wei Jin Southern and Northern Dynasties(魏晉南北朝), however, throughout the Su-Dang Dynasty(隋唐), Guanyu was Honored in the Wuchengwangmiao(武成王廟) then, was promoted from Hou(侯) to Gong(公), Gong(公) to King(王) in the Song-Yuan Dynasty(宋元). In the Ming-Qing Dynasty(明 淸) when the deification of Guanyu was proceeded most positively, he became a Di(帝) over a King and was endowed with the power over the Three Worlds(三界). He had an influence on nobility as well as the people in Folkbelief over Moral Spirits, and consequently rose through the ranks to become the spiritual guardian. The rulers gave him various names(封號) celebrating the life and work of Guanyu, In fact, they showed interests in the Belief of Guanyu as they attempted to establish an ideological base for the solution of the national disaster and maintenance of feudal system which came to the fore along with the reinforcement for emperor's power.