• Journal of Multimedia Information System
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• v.5 no.3
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• pp.163-170
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• 2018

We developed a multicast communication packet radio protocol using a time-sharing tablet system ("wireless token ring") to achieve the efficient exchange of files among packet radio terminals attached to swans. This paper provides an overview of the system and the protocol of the packet communications. The packet device forming the main part of the transceiver developed is the Texas Instruments CC2500. This device consists of one call-up channel and one data transmission channel and could improve error frame correction using FEC (forward error correction) with 34.8 kbps MSK and receiving power of at least -64 dBm (output 1 dBm at distance of 200 m using 3 dBi antenna). A time-sharing framework was determined for the wireless token ring using call sign ordinals to prevent transmission right loss. Tests using eight stations showed that resend requests with the ARQ (automatic repeat request) system are more frequent for a receiving power supply of -62 dBm or less. A wireless token ring system with fixed transmission times is more effective. This communication protocol is useful in cases in which frequency resources are limited; the energy consumed is not dependent on the transmission environment (preset transmission times); multiple terminals are concentrated in a small area; and information (position data and vital data) is shared among terminals under circumstances in which direct communication between a terminal and the center is not possible. The method allows epidemiological predictions of avian influenza infection routes based on vital data and relationships among individual birds based on the network topology recorded by individual terminals. This communication protocol is also expected to have applications in the formation of multiple in vivo micromachines or terminals that are inserted into living organisms.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.341-347
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• 2009

As a right-of-way security for the high power transmission line tower construction is becoming more and more difficult, the friendly environmental compact tower design is required. For a proper insulation for the compact tower, the polymer material are being tried. Some countries has already adapted, in the various polymer application and management data, polymer arm insulator to the transmission tower, and shown a stable operation. However, in our country, the polymer arm insulator has left much to be desired in the installation on the transmission line tower. But polymer material has been developed by high strength and technology and is expected to be used in various electric equipments. The polymer arm insulator is a one of good electric insulation materials to expand the power supply capacity in the rapid power demand increasement In this research, the new polymer am insulator is designed and its electric specifications are analyzed. Its mechanical specifications is verified through the field test on the compact tower which is modified by the polymer arm insulator.

• Journal of Periodontal and Implant Science
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• v.26 no.1
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• pp.47-67
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• 1996

The purpose of this study was to observe the effect of $Biocoral^R$ graft and bioglass 45S5 graft in combination with ePTFE membrane in periodontal osseous defects for new bone formation. Nine healthy dogs were used. Under general anesthesia, 3-wall defects were created on the mesial and distal surfaces of the maxillary right canines, the mesials of the maxillary right second premolars, the distals of the mandibular right canines and the mesials of the mandibular right third premolars. To induce periodontitis, a silicone rubber, $Provil^R$ light body, was injected under pressure into the defects. Ninety days later, $Provil^R$was removed and followed by thorough root planing. The followings were then applied in the mesial and distal defects of the maxillary right canines, the mesials of the maxillary right second premolars, the distals of the mandibular right canines and the mesials of the mandibular right third premolars by random selections : 1) ePTFE membrane only application, 2) $Biocoral^R$ graft, 3) $Biocoral^R$ graft and ePTFE membrane application, 4)Bioglass 45S5 graft, 5) Bioglass 45S5 graft and ePTFE membrane application. The membranes were removed 1 month later. The dogs were sacrified at 1, 2 and 3 months following the graft, and block sections were made, demineralized, embedded, stained and examined by light microscope and transmission electron microscope. On the sections from teeth treated with ePTFE membrane only, the defect demonstrated extensive connnective tissue and alveolar bone regeneration. The $Biocoral^R$ graft group demonstrated extensive bone regeneration compared with ePTFE membrane only group. In the $Biocoral^R$ graft plus ePTFE membrane group, regeneration of new alveolus and crest occurred within the defect. As the experimental period lengthened, bone regeneration was increased and bone bridge was formed among the graft particles. The but bioglass 45S5 graft group demonstrated extensive bone regeneration but the amount of new bone was less than that of the $Biocoral^R$ graft group. For the bioglass 45S5 graft plus ePTFE membrane group, the amount of new bone was also increased. As the experimental period lengthened, bone regeneration was increased. Multinucleated giant cells, fibroblasts and macrophages were observed. As the bone formation was increased, the number of such cells was decreased. In conclusion, the $Biocoral^R$ was found better than the bioglass 45S5 for new bone formation, and the use of ePTFE membrane alone or with $Biocoral^R$/bioglass 45S5 can be supported as potential methods of promoting bone formation.

• Korea Trade Review
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• v.41 no.5
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• pp.187-211
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• 2016

This study discusses the right of suspension of performance against anticipatory breach under SGA. Anticipatory breach originated in Hochster v De La Tour allows the innocent party to exercise immediately the right or rights reserved for the non-performance of obligations. But it has not been codified in English Law. Instead, under SGA s. 41 and s. 44, the seller may suspend his performance against the buyer' anticipatory breach. Lien under s. 41 and stoppage in transit under s. 44 are given only to the seller in a narrowly-defined situation. Under SGA s. 41, the unpaid seller is entitled to retain possession of goods where the buyer becomes insolvent. But under SGA s. 43, the unpaid seller loses the right of lien when he delivers goods to a carrier or other bailee or custodian for the purpose of transmission to the buyer without reserving the right of disposal, or when the buyer or his agent lawfully obtains possession of the goods, or by waiver of lien. Under SGA s. 44, the unpaid seller may exercise the right of stoppage in transit if the buyer becomes insolvent, despite the fact that the property of goods has passed or a bill of lading has been transferred to the buyer. But, under s. 45, the right of stoppage in transit is ended when the buyer or his agent takes delivery of goods. And where the buyer transfers a bill of lading to a sub-buyer, the unpaid seller loses his right to stop goods in transit.

• The Journal of the Korea Contents Association
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• v.11 no.10
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• pp.242-256
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• 2011

The activity to share personal daily life through social media is becoming more common. In this case, photographs as well as text are used a lot; it has been as easy as winking to clip others' photographs just as it's very easy to take and post pictures. If the picture is the photographic work protected by the copyright law, however, the clipping should be paid close attention. If you use others' photographic works without authorization, you infringe their copyright; if you post them on your social media such as blog, you infringe the right of reproduction, interactive transmission and exhibition. Even though the clipping is permitted, if you'd like to use the photographic works for a profit-making purpose, you should get additional authorization. Others' photographic works are occasionally altered and used for the purpose of avoiding the argument in relation to the infringement of copyright; this act means that it's the infringement of the right of reproduction, the right to preserve the integrity and the right of the production of derivative works for degrees of alteration. We can download others' photographic works with a few mouse clicks thanks to the technology of capturing the screen; we have to recognize that all the acts technically possible are not always legal.

• Journal of the Korean Society for information Management
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• v.31 no.4
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• pp.179-200
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• 2014

This study investigated the present situation of the use of cinematographic works and the problems of copyright. Surveys were conducted in public and university libraries for these. Also, content analyses were conducted to make sense of copyright problems in libraries. As a result, this study found that problems of copyright had occurred in various aspects related to public performance, lending, digitization and internet services according to the diversity of facilities for watching cinematographic works and library services. Also, the librarians' questions to the copyright were very various from the primary level to specific level. This study suggested that regular courses of study in library schools need to be opened to primitive understanding to copyright law and occupational training programs for librarians need to be opened to complementary education as revisions of copyright law. This study also suggested that the online Q&A services need to be started for librarians who have detailed copyright problems.

• Geomechanics and Engineering
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• v.37 no.3
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• pp.293-306
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• 2024

Influenced by the alternating effects of dynamic and static pressure during the mining process of close range coal seams, the surrounding rock support of cross mining roadway is difficult and the deformation mechanism is complex, which has become an important problem affecting the safe and efficient production of coal mines. The paper takes the inclined longwall mining of the 10304 working face of Zhongheng coal mine as the engineering background, analyzes the key strata fracture mechanism of the large inclined right-angle trapezoidal mining field, explores the stress distribution characteristics and transmission law of the surrounding rock of the roadway affected by the mining of the inclined coal seam, and proposes a segmented and hierarchical support method for the cross mining roadway affected by the mining of the close range coal seam group. The research results indicate that based on the derived expressions for shear and tensile fracture of key strata, the ultimate pushing distance and ultimate suspended area of a right angle trapezoidal mining area can be calculated and obtained. Within the cross mining section, along the horizontal direction of the coal wall of the working face, the peak shear stress is located near the middle of the boundary. The cracks on the floor of the cross mining roadway gradually develop in an elliptical funnel shape from the shallow to the deep. The dual coupling support system composed of active anchor rod support and passive U-shaped steel shed support proposed in this article achieves effective control of the stability of cross mining roadways, which achieves effective control of floor by coupling active support and preventive passive support to improve the strength of the surrounding rock itself. The research results are of great significance for guiding the layout, support control, and safe mining of cross mining roadways, and to some extent, can further enrich and improve the relevant theories of roof movement and control.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.141-147
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• 2019

Recently, the biggest issue in the electricity industry is the increase in renewable energy, and various technologies are being developed to ensure the capacity of the power system. In addition, super-grids linking power systems are being pushed to utilize eco-friendly energy between countries and regions worldwide. The HVDC transmission technology is required to link the power network between regions with different characteristics of the power system such as frequency and voltage. Until now, Korea has applied HVDC transmission technology that connects mainland and Jeju Island with submarine cables. But, the HVDC transmission technology is still developing for long-distance high-capacity power transmission from power parks on the east coast to load-tight areas near the metropolitan area. Considering the high population density and mountainous domestic environment, it is pushing for commercialization of the design technology of the ${\pm}500kV$ Double Bipole with metallic return wire transmission line to transmit large-scale power of 8 GW using minimal right of ways. In this paper, the insulation characteristics were studied for the design of double-bipole transmission tower with metallic return wire, which is the first time in the world. And the air insulation characteristics resistant to the various overvoltage phenomena occurring on transmission lines were verified through a full-scale impulse voltage test.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.8
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• pp.900-904
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• 2010

In this paper, a frequency tunable zeroth-order resonant(ZOR) antenna has been implemented. The ZOR characteristics of the proposed antenna is realized by using a composite right-and left-handed(CRLH) transmission line which consists of a rectangular slot on the ground plane of a mushroom structured antenna in order to minimize the antenna size. In addition, the tunable devices are introduced on the slotted ground plane for frequency tuning capability. Depending on the on and off states of the tunable device on the slotted ground plane, a shunt inductance value of the CRLH transmission line is changed and its resonant frequency becomes tunable. From the experimental results, the resonant frequency of the proposed antenna is changed from 4.92 GHz to 2.96 GHz. Additionally, the proposed antenna's size is reduced by 94.24 % compared with the half-wavelength patch antenna.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.9
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• pp.54-58
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• 2011

In this paper a dual-band Class-E power amplifier using Composite Right-/Left-Handed transmission lines and PIN diode is proposed. Dual-band operation is achieved by the frequency offset and nonlinear phase slope of CRLH TL for the matching network of power amplifiers. The proposed power amplifier has been realized by using in the input and the output matching network for high power added efficiency. PIN diode has been used to obtain the dual-band of power amplifier. The measured results show that output powers of 42.17 dBm and 41.43 dBm were obtained at 800 MHz and 1900 MHz, respectively. At this frequency, we have obtained the power-added efficiency(PAE) of 67.84 % and 65.31 % in two operation frequencies, respectively.