• Journal of Radiation Protection and Research
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• v.11 no.1
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• pp.70-76
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• 1986

In order to establish the national standards of neutron measurements, a manganese sulphate ($MnSO_4$) bath system was developed under the IAEA technical support. This bath system was made up of a spherical s.s. 316 L bath, of 3.5 mm thick and of 125 cm internal diagmeter, filled with a manganese sulphate solution, a solution circulating system, and a $^5Mn\;{\gamma}-ray$ monitoring system. The solution pumped from the bath was introduced into a Marinelli beaker-type monitor vessel which was equipped with two seperate detectors, $3.8cm{\phi}{\times}3.8cm$ NaI(T1) crystals. The performance of the system were tested using the neutron sources, $^{241}Am-Be\;and\;^{252}Cf$, mounted at the center of the bath. From the decay curve analysis of $^{56}Mn$ activity, neutron emission rate of $^{252}Cf$ by the comparative method was obtained to be $3.71{\times}10^7\;n/s\;per\;50{mu}g$ as of November 15, 1985.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.3
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• pp.422-428
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• 2006

Dentin bonding system have recently been developed in an effort to simplify and shorten bonding procedure. The intent of this study was to evaluate microleakage of newer generation of dentin bonding system comparing with other generations. Forty extracted human premolar teeth were randomly assigned to four groups for bonding : the 4th generation bonding system (Scotchbond Multi-Purpose). the 5th generation bonding system (Clearfil SE Bond), 6th generation bonding system (AQ bond) and 7th generation bonding $system(i-bond)^{TM}$ Class V cavities were prepared in buccal and lingual surface. The cavities were restored with composite resin (Z100) after the application of dentin bonding systems according to the instructions of the manufacturer Samples were thermocycled and immersed in methylene blue dye(2%). Each sample was sectioned with Isomet and evaluated for microleakage using stereomicroscopy. The mean value of the microleakage in 7th generation bonding system was greater than those of 4, 5, 6th generation dentin bonding system. Statistically, the mean values of microleakage between 4th and 7th generation bonding system were significantly different from each other (p<0.05).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.2
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• pp.78-84
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• 2001

The binary forsterite($Mg_2SiO_4$)/spinel ($MgAl_2O_4$) system, a possible refractory for industrial applications, is investigated for their density and grain growth the same firing conditions as the each component material between $1400^{\circ}C$ and $1700^{\circ}C$ ($1650^{\circ}C$). The forsterite grain growth exponent is established to be equal to 5 for all compositions within this binary system. Generally; the spinel addition to forsterite inhibited the forsterite grain growth. The activation energies for the forsterite grain growth of the eight compositions(weight ratio of forsterite/spinel) within the binary system are determined to be: 952$\pm$79(95/5), 363$\pm$37(90/10), 219$\pm$21(80/20), 220$\pm$44(70/30), 112$\pm$16(50/50), 112$\pm$23(30/70), 198$\pm$26(10/90), and 121$\pm$12(5/95) KJ/mol. The more forsterite is contained within the binary system, the higher value the activation energy for forsterite grain growth. It is considered that the forsterite grain growth at the higher forsterite compositions are more inhibited by spinel than that of the lower forsterite compositions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.5
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• pp.688-694
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• 2018

The transition section of the overhead rigid conductor rail (ORCR) consists of a direct induction device and a limit point to prevent the power supply failure and failure of the electric railway vehicle pantograph due to the difference of the uplift in the catenary line. In T-Bar transition section, a twin simple catenary is mostly installed between the overhead catenary system (OCS) in the ground section and the ORCR in the underground section. In this paper, we compare and analyze the possibility of replacing the twin simple catenary with heavy simple catenary. The reliability of numerical analysis results was confirmed by comparing field test with numerical results. Comparing the numerical results of the twin simple catenary with the heavy simple catenary in the transition section, the difference uplift is 5.9[mm] on average. When applying heavy simple catenary instead of twin simple catenary, the slight difference of uplift can be compensated by adjusting the height of hanger-ear or support bracket.

• International Journal of Advanced Culture Technology
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• v.5 no.2
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• pp.90-97
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• 2017

The Internet of Things(IoT) market is expected to grow from 15.5billion to 75.4 billion by 2015-2025. As the number of IoT devices increases, the amount of data that is sent to the cloud is increasing. Today's Cloud Computing models are not suited to handle the vast amount of data generated by IoT devices. In this paper, we propose a Cooperation Coordinator System that reduces server load and improved real-time processing capability under specific circumstances by using Band-Cloud. The cooperation coordinator system dynamically forms the cloud when cooperation is needed between mobile devices located near. It is called Band-Cloud. Band-Cloud provides services entrusted by Central Cloud. This paper describes the proposed system and shows the cooperation process using the Android-based mobile devices and Wi-Fi Direct technology. Such a system can be applied to cases where real-time processing is required in a narrow area such as a hospital ward or a school classroom.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.2
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• pp.315-323
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• 2015

Nowadays, it is expected that mobility loads such as electric railways and electric vehicles will be penetrated gradually and affect on the power system stability by their load characteristics. Various researches have been carried out about electric vehicles for the recent decade though the load of electric railway could be forecasted because of the specified path and timetable, is a field with a long historic background. Some precise 5th polynomial equations are required to analyze the power system stability considering mobility load to be increased in the immediate future while the electric railway dispatching simulator uses load models with constant power and constant impedance for the system analysis. In this paper, seasonal urban railway load models are established as the form of 5th polynomial equations and substation load modeling methods are proposed merging railway station load models and general load models. Additionally, load management effects by the load modeling are confirmed through the case studies, in which seasonal load models are developed for Seoul Subway Line No. 2, Gyeongui Line and Airport Railroad and the substation load change is analyzed according to the railway load change.

• Journal of the Korean Chemical Society
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• v.54 no.6
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• pp.727-730
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• 2010

A tricyclic ring system bearing new stereogenic center namely 2,3-dihydro[1]benzothieno[3,2-b]pyrrole 4,4-dioxide was synthesized by asymmetric photoisomerization of 2,3-dihydropyrrolo[1,2-b]benzisothiazole 5,5-dioxide by irradiation with 245 nm emission of the low-pressure mercury lamp. The chemical structure and the purity of the photoproduct were delineated preliminarily by IR, NMR, and MS and finally confirmed by single crystal X-ray crystallography.

• Electronics and Telecommunications Trends
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• v.36 no.6
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• pp.13-24
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• 2021

Industrial networks has been developing various technologies from fieldbus technology to industrial Ethernet and time-sensitive networking. The industry expects that the 5G mobile network will solve the diverse and highly specific industrial site requirements. Accordingly, 3GPP has been developing standard functions to provide ultra-high reliability, ultra-high speed, ultra-connection, and ultra-low latency services, and 3GPP Rel-16 began developing ultra-low latency and ultra-high reliability communication functions for 5G mobile networks to support vertical industries. In this paper, we show the related standardization trends and requirements to apply industrial IoT service scenarios to 5G mobile networks, and in particular, we introduce 5G system features and extended 5G system architecture to provide time sensitive communication and time synchronization services.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.5
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• pp.580-585
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• 1988

In this paper, a low frequency acoustic microscope system has been built for the purpose of detecting subsurface defects in materials. The lateral resolution of acoustic microscope is studied and analyzed in order to evaluate that system performance. And a NDE technique is demonstrated by using this system. In the focused and defocused mode of operation, the acoustic microscope system showed in experiment that its lateral resolution was about 0.5 mm at a frequency of operation of 3MHz on a fused-quartz sample with seeded circular cracks ranged in size from 0.2 mm to 1.0 mm in diameter wihtin 1 mm of the surface. It also showed the acoustic image of 100 won coin with fine contrast.

• Journal of IKEEE
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• v.13 no.2
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• pp.220-223
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• 2009

A simple measurement system is built to estimate the dual-antenna diversity gain at 2.4GHz easily in open lab environment. To obtain multipath fading propagation channel, the system consists of two transmission horn that placed on opposite direction and a rotating stage mechanically changing the position of test dual-antenna with time over distance greater than one wavelength. Estimated diversity is nearly same as theoretical value such that measured diversity gain of 30mm separated is about 6dB similar to theoretical value of 5.7dB and increases monotonically with the increasing separation distance as predicted by the theory. Proposed measurement system that is simple enough to fit in a small space can evaluate the performance of various dual-antennas with a reasonable accuracy with lower 5% difference between the ten sets of measured waveform distribution and theoretical Rayleigh cumulative distribution.