• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.2011-2018
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• 2021

Nowadays, evaluation of amounts and distributions of radioactive waste is an important preparatory step in the process of nuclear reactor decommissioning. For tentative estimation of radioactive waste, a cell-based rigorous 2 step (R2S) method usually is used; however, a poor resolution caused by the averaged flux and spectrum in a cell is still a great challenge because of leading to underestimated or overestimated results. To overcome the poor resolution, several systems were introduced. Neither system, however, provides any function for evaluation of radioactive waste amount and distribution. Thus, it is additionally required to classify radioactive waste based on the results of activation calculation. In this study, the advanced R2S (AR2S) system was developed. To verify the performance of the system, its results for a verification problem were compared with those of the cell-based R2S method. The results showed good agreement, which is to say, within 2.0% relative error. Also, several characteristics of fine/coarse mesh were analyzed. To demonstrate the performance of the AR2S system, the radioactive waste from the Japan Power Demonstration Reactor (JPDR) was estimated, and the result indicated a high-resolution distribution. Therefore, it is expected that the AR2S system will prove useful for precise evaluation of radioactive waste.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.22-29
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• 2022

Recently, with the development of mobile computing power, mobile-based VR and AR services are being developed. Due to network performance and computing power constraints, VR and AR services using large-capacity 3D content have limitations. A study on an efficient 3D content load method for a mobile device is required. The conventional method downloads all 3D content used for AR services at the same time. In this paper, we propose an active 3D content load according to the user's track. The proposed method is a partitioned 3D object load. Edge servers were installed for each area and connected through the MESH network. Partitioned load the required 3D object in the area referring to the user's location. The location is identified through the edge server information of the connected AP. The performance of the proposed method and the conventional method was compared. As a result of the comparison, the proposed method showed a stable Mobile AR Service. The results of this study, it is expected to contribute to the activation of edge server-based AR mobile services.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1C
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• pp.54-62
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• 2012

A Wi-Fi mesh network providing multi-hop wireless connections based on IEEE 802.11 PHY/MAC technology has recently received a significant attention as a network infrastructure that interconnects RFID systems and wireless sensor networks (WSNs). However, the current IEEE 802.11 contention-based MAC protocol cannot fully utilize the network capacity due to eithor frame collisions or unused network resources. In this paper, we propose a novel multi-channel scheduling MAC (MCS-MAC) protocol for Wi-Fi mesh networks. Under the secondary interference model of Wi-Fi mesh networks, the MCS-MAC protocol can maximize the network throughput via activation of collision-free links that has a maximal link weight. Through the simulations, we show that the throughput of the MCS-MAC protocol is at least three times higher than that of existing MAC protocols in Wi-Fi mesh networks.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2410-2414
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• 2008

Human heart valves diseased by congenital heart defects, rheumatic fever, bacterial infection, cancer may cause stenosis or insufficiency in the valves. Treatment may be with medication but often involves valve repair or replacement (insertion of an artificial heart valve). Bileaflet mechanical heart valves (BMHVs) are widely implanted to replace the diseased heart valves, but still suffer from complications such as hemolysis, platelet activation, tissue overgrowth and device failure. These complications are closely related to both flow characteristics through the valves and leaflet dynamics. In this study, the physiological flow interacting with the moving leaflets in a bileaflet mechanical heart valve (BMHV) is simulated with a strongly coupled implicit fluid-structure interaction (FSI) method which is newly organized based on the Arbitrary-Lagrangian-Eulerian (ALE) approach and the dynamic mesh method (remeshing) in FLUENT. The simulated results are in good agreement with previous experimental studies. This study shows the applicability of the present FSI model to the complicated physics interacting between fluid flow and moving boundary.

• Transactions of the Korean hydrogen and new energy society
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• v.11 no.4
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• pp.189-202
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• 2000

$AB_2$ type Zr-based Laves phases alloys have been studied for potential application as a negative electrode in a Ni-MH battery. The $AB_2$-type electrodes have a much higher energy density than $AB_5$-type electrodes per weight, however they have some disadvantages such as poor activation behavior and cycle life etc. Nonetheless, the $AB_2$-type electrodes have been studied very extensively due to their high energy density. In this study, in order to develop the cycle life, the Mn of $AB_2$ alloy composition was substituted partially by Mo. The alloys were melted by arc furnace and remelted 4-5 times for homogeneity. The alloy powder was used below 200-325 mesh for experiments. The structures and phases of the alloys were analyzed by XRD, SEM and EDS, and measured the curve of a pressure-composition isotherms. The electrodes were prepared by cold pressing of the copper-coated(25 wt%) alloy powders, and tested by a half cell. The results are summarized as follows. The cycle life was improved with the increase of Mo amount in $Zr_{1-x}Ti_xV_{0.4}Ni_{1.2}Mn_{0.4}Mo_y$(x=0.3, 0.4) and the activation was faster, whereas the discharge capacity decreased.

• Korean Journal of Food Science and Technology
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• v.48 no.2
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• pp.147-152
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• 2016

This study was conducted to investigate the physicochemical quality properties and provide basic data for the activation of traditional Kamju of juice type product prepared by mixing malt and extruded rice collet powder. Malt extracts were prepared by extracting the mixture of malt and water at a weight ratio of 25:75 after soaking for 2 h at $45^{\circ}C$. Rice collet powder was prepared by adjusting the barrel temperature to $95^{\circ}C$, screw speed to $3.07{\times}g$, discharge port diameter to 7 mm and a raw material input to 50 kg/h, the powder was then ground to a particle size of 80 mesh. The physicochemical characteristics (pH, color, viscosity, reducing sugars, number of viable cells, free amino acids) and sensory evaluations were conducted at various time points during the saccharification and at different mixing ratios of the extruded rice collet powder to malt extract (5:95, 15:85, 25:75, 35:65, each at $55^{\circ}C$ for 9 h). As a result, with an increase in the proportion of the extruded rice collet powder and saccharification time, the physicochemical properties of traditional Kamju significantly improved (p<0.05). A mixing ratio of 35:65 rice collet powder to malt extract and a saccharification time of 9 h were found to be the most desirable conditions. However, based on the sensory evaluation, a mixing ratio of rice collet powder and malt extract of 25:75 and a saccharification time of 5 h resulted in the most preferable palatability of traditional Kamju (p<0.05). Therefore, the mixing ratio and saccharification time should be determined to provide a better choice with respect to the taste and economic aspects of traditional Kamju.