• Composites Research
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• v.34 no.2
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• pp.96-100
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• 2021

The lightweight industry continuously demands reliable near-net-shape fabrication where the preform just out-of-machine is close to the final shape. In this study, different half-finished preforms are made π-beams. Then the preforms are unfolded to make a 3D shape with integrated structure of fibers, providing easier handling in the further processing of composites. Several 3D textile preforms are made using weaving technique and are examined after resin infusion for mechanical properties such as inter-laminar shear strength, compressive strength and tensile strength. Considering that the time and labor are important parameters in modern production, 3D weaving technique reduces the manufacturing steps and therefore the costs, such as hand-lay up of textile layers, cutting, and converting into preform shape. Hence this 3D weaving technique offers many possibilities for new applications with efficient composite production.

• Asian Journal of Atmospheric Environment
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• v.8 no.3
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• pp.154-161
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• 2014

The present study was undertaken to evaluate the chemical characteristics of Asian dust (hereafter called "AD") particles with the aid of the most advanced micro-PIXE (Particle-induced X-ray emission) analytical technique. To this end, size-selected particles were sampled on a rural peninsula of Korea (Byunsan, 35.37N; 126.27E) during AD and non-AD periods in 2004. The coarse particle (> $2{\mu}m$) number density during an AD event were 170 times higher than those of the non-AD counterpart. The average net-count of silica in individual particles collected on AD event was roughly 11 times higher than that of non-AD counterpart. The X-ray net-counts of trace elements (Zn, Co, Mn, and V) were also considerably high in AD relative to the non-AD day. Particle classification based on the inter ratio analysis of elemental net-count suggests that a large portion of the coarse particles collected during AD event underwent chemical transformation to a certain degree. The visual interpretation of micro-PIXE elemental maps and elemental localization data in and/or on individual AD particles clarified the internal mixture of AD particles with sea-salt and artificial metallic particles.

• Nuclear Engineering and Technology
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• v.41 no.4
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• pp.549-560
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• 2009

Over the last three decades, nuclear technology development has played a vital role in the socio-economic development of the Republic of Korea. This study, being the first of its kind, focuses on quantifying the actual economic contribution of nuclear technologies to economic development by evaluating the net benefit of the nuclear power with respect to the country's Gross Domestic Product (GDP). An input-output analysis was employed as a methodological approach to analyze inter-industrial economic activities by calculating the industrial value added as a means of the economic contribution during the period of 1980 to 2005. The industrial value added of nuclear technologies was estimated from the construction and operation of nuclear power (backward-linked industrial value added) and from the industrial activities attributed to the electricity generated by the nuclear power (forward-linked industrial value added). It was found that the total net contribution of nuclear technologies as a percentage share of GDP amounted to 2.38% in 2005.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.680-684
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• 2001

Since establishment some 25 year ago, AMITA Corporation has continued its attempts in meeting customer needs, in reducing costs for waste treatment. The solutions we have proposed in the past made use of our networks entailing Japan as well as the East Asian region. However, as enterprises have changed their perspective approaching environmental issues recently, as needs diversify, AMITA too has been changing its strategy to incorporate the use of Information Technology to provide consulting services. AMITA has set its goals in promoting modernization of the waste treatment industry, and optimizing the recycling market to reduce environmental impacts.

• Nuclear Engineering and Technology
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• v.44 no.2
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• pp.207-224
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• 2012

This article discusses selects of some outstanding problems in nuclear reactor analysis, with proposed approaches thereto and numerical test results, as follows: i) multi-group approximation in the transport equation, ii) homogenization based on isolated single-assembly calculation, and iii) critical spectrum in Monte Carlo depletion.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4357-4366
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• 2023

MARS-KS, a domestic regulatory confirmatory code of Republic of Korea, had been developed by integrating RELAP5/MOD2 and COBRA-TF. The integration of COBRA-TF allowed to extend the capability of MARS-KS, limited to one-dimensional analysis, to multi-dimensional analysis. The use of COBRA-TF was mainly focused on subchannel analyses for simulating multi-dimensional behavior within the reactor core. However, this feature has been remained as a legacy without ongoing maintenance. Meanwhile, MARS-KS also includes its own multidimensional component, namely MULTID, which is also feasible to simulate three-dimensional convection and diffusion. The MULTID is capable of modeling the turbulent diffusion using simple mixing length model. The implementation of the turbulent mixing is of importance for analyzing the reactor core where a disturbing cross-sectional structure of rod bundle makes the flow perturbation and corresponding mixing stronger. In addition, the presence of this turbulent behavior allows the secondary transports with net mass exchange between subchannels. However, a series of assessments performed in previous studies revealed that the turbulence model of the MULTID could not simulate the aforementioned effective mixing occurred in the subchannel-scale problems. This is obvious consequence since the physical models of the MULTID neglect the effect of mass transport and thereby, it cannot model the void drift effect and resulting phasic distribution within a bundle. Thus, in this study, the turbulence mixing model of the MULTID has been improved by means of the inter-channel mixing model, widely utilized in subchannel analysis, in order to extend the application of the MULTID to small-scale problems. A series of assessments has been performed against rod bundle experiments, namely GE 3X3 and PSBT, to evaluate the performance of the introduced mixing model. The assessment results revealed that the application of the inter-channel mixing model allowed to enhance the prediction of the MULTID in subchannel scale problems. In addition, it was indicated that the code could not predict appropriate phasic distribution in the rod bundle without the model. Considering that the proper prediction of the phasic distribution is important when considering pin-based and/or assembly-based expressions of the reactor core, the results of this study clearly indicate that the inter-channel mixing model is required for analyzing the rod bundle, appropriately.

• Korean Journal of Social Welfare
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• v.62 no.3
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• pp.31-58
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• 2010

Using Seoul Welfare Panel Study, this research examines regional differentials in income and asset between Gangnam households and Non-Gangnam households in Seoul. Applying the Oaxaca decomposition method, it also decomposes factors associated with the differentials into explained and unexplained components. Results show that average monthly income is about 4 million won for Gangnam households and 3.2 million won for Non-Gangnam households. The explained component accounts for most of the income differential, which mainly originates from differences in the distributions of individual and household characteristics associated with the monthly income. The net asset differential between the two regions is much greater than the income differential. The net asset is about 460 million won for Gangnam households and approximately 280 million won for Non-Gangnam households. Most of the net asset differential is remained unexplained after controlling for covariates which measure demographic characteristics of householders and various features of labor market in which household members are employeed. It implies that other factors such as inter-generational transfers of wealth may play a significant role in creating the net asset differential.

• Nuclear Engineering and Technology
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• v.54 no.7
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• pp.2599-2605
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• 2022

The Korea Retrospective Dosimetry network (KREDOS) performed an inter-laboratory comparison to confirm the harmonization and reliability of the results of retrospective dosimetry using mobile phone. The mobile phones were exposed to ¹⁹²Ir while attached to the human phantoms in the field experiment, and the exposure doses read by each laboratory were compared. This paper describes the reference dosimetry performed to present the reference values for inter-comparison and to obtain additional information about the dose distribution. Reference dosimetry included both measurement using LiF:Mg,Cu,Si and calculation via MCNP simulation to allow a comparison of doses obtained with the two different methodologies. When irradiating the phones, LiF elements were attached to the phones and phantoms and irradiated at the same time. The comparison results for the front of the phantoms were in good agreement, with an average relative difference of about 10%, while an average of about 16% relative difference occurred for the back and side of the phantom. The differences were attributed to the different characteristics of the physical and simulated phantoms, such as anatomical structure and constituent materials. Nevertheless, there was about 4% of under-estimation compared to measurements in the overall linear fitting, indicating the calculations were well matched to the measurements.

• Journal of Korea Multimedia Society
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• v.9 no.5
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• pp.635-648
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• 2006

As the advances of Internet infra structure and the support of console and mobile for network games, the industry of online game has been growing rapidly, and the online game traffic in the Internet has been increasing steadily. For design and simulation of game network, the analysis of online game traffic have to be preceded. Therefore a number of papers have been proposed for the purpose of analyzing the traffic data of network games and providing the models. We make and use GameNet Analyzer as a dedicated tool for game traffic measurement and analysis in this paper. We measure the traffic of FPS Quake 3, RTS Starcraft and MMORPG World of Warcraft (WoW), and analyze the packet size, packet IAT(inter-arrival time), data rate and packet rate according to the number of players and in-game behaviors. We also present the traffic models using measured traffic data. These analysis and models of game traffic can be used for effective network simulation, performance evaluation of game network and the design of online games.

• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1428-1435
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• 2019

The total ionizing dose (TID) and non ionizing energy loss (NIEL) effects of 100 MeV phosphorous ($P^{7+}$) and 80 MeV nitrogen ($N^{6+}$) ions on 200 GHz silicon-germanium heterojunction bipolar transistors (SiGe HBTs) were examined in the total dose range from 1 to 100 Mrad(Si). The in-situ I-V characteristics like Gummel characteristics, excess base current (${\Delta}I_B$), net oxide trapped charge ($N_{OX}$), current gain ($h_{FE}$), avalanche multiplication (M-1), neutral base recombination (NBR) and output characteristics ($I_C-V_{CE}$) were analysed before and after irradiation. The significant degradation in device parameters was observed after $100MeV\;P^{7+}$ and $80MeV\;N^{6+}$ ion irradiation. The $100MeV\;P^{7+}$ ions create more damage in the SiGe HBT structure and in turn degrade the electrical characteristics of SiGe HBTs more when compared to $80MeV\;N^{6+}$. The SiGe HBTs irradiated up to 100 Mrad of total dose were annealed from $50^{\circ}C$ to $400^{\circ}C$ in different steps for 30 min duration in order to study the recovery of electrical characteristics. The recovery factors (RFs) are employed to analyse the contribution of room temperature and isochronal annealing in total recovery.