• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.275-281
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• 2012

Community network is a communication environment where heterogeneous devices can access and communicate with each other at any time and at any space to share information. To do so, mobile devices are required to be self-configured even in absence of communication infrastructures. Semi-infrastructured wireless ad-hoc network is a promising solution to meet with such a requirement. This paper proposes the VTC(virtual topology coordinator) system as an evaluation tool for examining network protocols that are intended to be deployed in the semi-infrastructured ad-hoc networks. VTC emulates multi-hops wireless network topology virtually using a mechanism of selective receiving MAC frame in a small area, where only a single hop communication is available. VTC system cannot consider all properties introduced in real wireless network, but do more wireless properties than verification through simulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.529-534
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• 2002

It was recommended for all ship engaged in international voyages to carry the dedicated Digital Selective Calling receiver, DSC equipment, VHF transceiver, etc according to Global Maritime Distress & Safety System. Also International Maritime Organization recommended for navigation and communication equipments to applicate the EMC regulations, therefore most of electronic equipments using in the vessel to be faced with problems to cope with new regulations. This study has applied and analyzed the EMC for an equipment integrated with Ch.70 dedicated DSC receiver, DSC equipment, VHF transceiver and groped for solutions to cope with. The test has applied the electromagnetic interference such as the measurement for unwanted emissions from conductive & radio emission and the electromagnetic susceptibility such as the immunity from voltage, frequency variation and electro static discharge, hence comes to be understand the problems related with the power and the earth.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.747-749
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• 2017

To protect financial services against danger of financial accidents and customer information leakage caused by malware, injection attack and so on, Financial Services Commission announced "Financial Networks Security Enhancement Comprehensive Plan", which suggests the guideline of protecting customer information and providing secure financial services by separating network topology and then makes the financial company use network partitioning system. In consequence of this policy, financial companies respectively chose between the physical partitioning mechanism or the logical partitioning mechanism according to their IT environment. This paper suggests an efficient infrastructure configuration plan for making the logical network partition, by comparison of a construction of traditional general equipment and an integrated HCI(Hyper Converged Infrastructure) through 'Hyper Converged' which is one of virualization techniques for developing currently, and the case study of the integrated HCI method.

• Information and Communications Magazine
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• v.12 no.10
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• pp.76-86
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• 1995

In this paper, we propose a new network architecture for the future broadband personalized multimedia network. We first consider the service and technical requirements for supporting future advanced services such as personalized and intelligent communication services. In addition, we consider the design and implementation of the future network. Considering these requirements. we propose a new network architecture and its control scheme that can efficiently support the future personalized and intelligent services as well as broadband multimedia services. The network provides only a relatively simple core set of functions such as basic end-to-end connectivity, integrated access, and primitive network intelligence of user location. More intelligent features (e.g., personalized calling, virtual private networking and so on) can be offered through the additional network facilities or computing devices through an intelligent network.

• Resources Recycling
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• v.24 no.4
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• pp.50-55
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• 2015

In this study, we have investigated solvent extraction of Ga and recovery of high pure Ga solution from MOCVD dust for manufacturing of LED chip. Effect of extractan, concentration of extractant were examined for choosing the more effective extractant and high pure Ga solution was fabricated by multi-stage extraction/stripping process. For extraction/separation of Ga based on the analysis of raw-material in previous study, 3 different extractants PC 99A, DP-8R, Cyanex 272 has been investigated and the extraction efficiency of 1.5 M Cyanex 272 was 43.8%. It was conformed that extraction efficiency of Ga was 83% in multi-stage extraction and 5N high purity Ga stripping solution without impurities also obtained.

• The KIPS Transactions:PartB
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• v.14B no.3 s.113
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• pp.145-152
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• 2007

In this paper, we propose an automatic extraction model for unknown translations and implement an unknown translation extraction system using the proposed model. The proposed model as a phrase-alignment model is incorporated with three models: a phrase-boundary model, a language model, and a translation model. Using the proposed model we implement the system for extracting unknown translations, which consists of three parts: construction of parallel corpora, alignment of Korean and English words, extraction of unknown translations. To evaluate the performance of the proposed system, we have established the reference corpus for extracting unknown translation, which comprises of 2,220 parallel sentences including about 1,500 unknown translations. Through several experiments, we have observed that the proposed model is very useful for extracting unknown translations. In the future, researches on objective evaluation and establishment of parallel corpora with good quality should be performed and studies on improving the performance of unknown translation extraction should be kept up.

• Korean Journal of Construction Engineering and Management
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• v.19 no.1
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• pp.32-42
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• 2018

The importance of facility maintenance management cannot be overemphasized in that not only the value but also the performance of the facility is determined by the level of maintenance. The maintenance cost of the facility ranges from 3 to 10 times the initial construction cost depending the type and use of the facility over the life span. This maintenance importance is increased for the group of facilities and even more critical when the facilities compete for the limited budget with the limited resources such as manpower and equipment. This study analyzed sixteen public facility management corporations primarily for three items: 1) facility management system, 2) long-term rehabilitation plan, 3) the rehabilitation selection system. This paper provides and recommends the key elements of the facility maintenance management system based on the analysis of the sixteen corporations.

• Progress in Medical Physics
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• v.13 no.3
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• pp.135-138
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• 2002

Fractionated stereotactic radiosurguy (FSRS) requires precise and reproducible patient set up. For these reasons non-invasive mask fixation methods have been used in Linac based FSRS. In this study, we measured and assessed the isocenter reproducibility using a commercial head mask fixation system based on thermoplastic materials. For the verification and the measurement of isocenter deviation a special acrylic brain phantom was designed. The designed phantom has 22 vertical rods and each rod has different lengths. At the end of the 8 rods, the monochromic film is attached and irradiated due to planned target position. Deviations of isocenter were measured separately for each direction. The mean deviation showed 0.4 mm in longitudinal direction, 0.1 mm in the lateral direction, 0.1 mm in the anterior-posterior direction of the treatment couch. The data demonstrates the high accuracy and reproducibility. This study reinforces previous literature published.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.620-625
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• 2001

The pulpectomy or root canal treatment on primary teeth is to be done when there is evidence of chronic in flammation or necrosis in the radicular pulp. Due to the tortuous and ribbon-shaped anatomy of the primary teeth, the instrumentation of endodontic hand files and barbed broaches is not an easy procedure. Recently, many automatic Ni-Ti rotary instruments have been developed and has made endodontic treatment easier and faster. This report describes two cases of root canal treatment on primary molars using Ni-Ti rotary files. The cervical constricture was eliminated by the crown-down method, as smaller file proceeded unhindered into the apical third of the canal. In addition, the crown-down technique enhanced the efficacy of the endodontic irrigant. The use of rotary instrumentation for primary teeth seemed to be a more effective way to debride the uneven walls of primary teeth.

• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.305-313
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• 2001

Conductivity is an important thermal property which governs heat transfer in a solid medium. Generally, the determination of conductivity in concrete is very difficult, because concrete is a heterogeneous material composed of cement, water, aggregate, et cetera and time dependent material of which properties change with curing age. In this study, influencing factors on thermal conductivity of concrete are quantitatively investigated by QTM-D3, a conductivity tester developed in Japan. Then, a prediction equation of thermal conductivity of concrete is suggested from the regression analysis of test results. To consider the factors influencing thermal conductivity of concrete, mortar, and cement paste, seven testing variables (age, amount of cement, types of admixtures, amount of coarse aggregate, fine aggregate ratio, temperature, and humidity condition) of the specimens are used. According to the experimental results, the amount of coarse aggregate and humidity condition of specimen are the main factors affecting the conductivity of concrete. Meanwhile, the conductivity of mortar and cement paste is strongly affected by the amount of cement and types of admixtures. However, the curing age has minor effect on the conductivity variation. Finally, the prediction formula of concrete conductivity as a function of aggregate amount, fine aggregate ratio, specimen temperature, and humidity condition is developed.