• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.3910-3917
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• 2021

Reactor fuel's power distribution plays a vital role in designing the new generation thermionic Space Reactor Power Systems (SRPS). In this paper, the 1/12th SPACE-R's full reactor core was numerically analyzed with two kinds of different axial power distribution, to identify their impacts on thermal-hydraulic and thermoelectric characteristics. In the benchmark study, the maximum error between numerical results and existing data or design values ranged from 0.2 to 2.2%. Four main conclusions were obtained in the numerical analysis: a) The axial power distribution has less impact on coolant temperature. b) Axial power distribution influenced the emitter temperature distribution a lot, when the core power was cosine distributed, the maximum temperature of the emitter was 194 K higher than that of the uniform power distribution. c) Comparing to the cosine axial power distribution, the uniform axial power distribution would make the maximum temperature in each component of the reactor core much lower, reducing the requirements for core fuel material. d) Voltage and current distribution were similar to the axial electrode temperature distribution, and the axial power distribution has little effect on the output power.

• The KIPS Transactions:PartC
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• v.9C no.3
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• pp.331-336
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• 2002

In this paper, we propose a new distribution and renewal scheme for a group key suitable for secure mobile communications based on identification protocol, in which all members of the group can reshare the new group common key except revoked members by using a key distribution center (a trusted center). The security of this scheme is based on the difficulty of the discrete logarithm problem. The proposed scheme can be appropriately managed in case that terminal's capability of storage and computing power is relatively small and more than one caller are revoked. It also renews a group key easily when the center changes this key intervally for security.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.957-966
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• 2020

This paper presents the virtual mass method to implement the prediction of total resistance for ice-going ship in floe ice region based on the combined method of CFD and DEM. Two ways of floe ice distribution are adopted for the analysis and comparison. The synthetic ice model test has been conducted to determine the optimal virtual mass coefficients for the two different floe ice distributions. Moreover, the further verification and prediction are developed in different ice conditions. The results show that, the fixed and random distributions in numerical method can simulate the interaction of ship and ice vividly, the trend of total resistance varying with the speed and ice concentration obtained by the numerical simulation is consistent with the model test. The random distribution of floe ice has higher similarity and better accuracy than fixed distribution.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.11
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• pp.5218-5233
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• 2018

The coexisting wireless body area networks (WBAN) is a very challenging issue because of strong inter-networks interference, which seriously affects energy consumption and spectrum utilization ratio. In this paper, we study a power control strategy with nearest neighbor nodes distribution for coexisting WBAN based on stochastic geometry. Using homogeneous Poisson point processes (PPP) model, the relationship between the transmission power and the networks distribution is analytically derived to reduce interference to other devices. The goal of this paper is to increase the transmission success probability and throughput through power control strategy. In addition, we evaluate the area spectral efficiency simultaneously active WBAN in the same channel. Finally, extensive simulations are conducted to evaluate the power control algorithm.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.2
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• pp.123-133
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• 2002

In Network Environment, Kerberos certification mechanism to require Kerberos server in other area unconditionally belief. Also, Kerberos server in cooperation area must be share server of other area and secret key. To solve these two problems, this paper proposed safe security mechanism of doing to ably IETF CAT's PKINIT/PKCROSS a1gorithm with Public Key Infrastructure and use Directory System and service between realms do trust and prove each Kerberos trust center base. Also, Although Kerberos server of each area must be foreknowing each server's secret key and public key, Obtain through Trust center and acquire each area's public key and common symmetric key, Application server excluded process that must register key in Key Distribution Center.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.7
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• pp.1180-1190
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• 2020

Objective: To develop healthier comminuted meat products to meet consumer demand, the gel properties, rheological properties, microstructure and water distribution of pork meat batters formulated with various amounts of bamboo shoot dietary fiber (BSDF) were investigated. Methods: Different levels of BSDF (0% to 4%) were added to pork batters, and the pH, color, water-holding capacity, texture and rheological properties of pork batters were determined. Then, pork batters were analyzed for their microstructure and water distribution using scanning electron microscopy (SEM) and low-field nuclear magnetic resonance (LF-NMR). Results: Compared with the control, BSDF addition into meat batters showed a significant reduction in L^*-value and a significant increase in b^*-value (p<0.05). BSDF addition of up to 4% reduced the pH value of pork batters by approximately 0.15 units; however, the cooking loss and expressible water loss decreased significantly (p<0.05) with the increased addition of BSDF. The hardness and gel strength were noticeably enhanced (p<0.05) as the content of BSDF increased. The rheological results showed that BSDF added into pork batters produced higher storage modulus (G') and loss modulus (G") values. The SEM images suggested that the addition of BSDF could promote pork batters to form a more uniform and compact microstructure. The proportion of immobilized water increased significantly (p<0.05), while the population of free water was decreased (p<0.05), indicating that BSDF improved the water-holding capability of pork batters by decreasing the fraction of free water. Conclusion: BSDF could improve the gel properties, rheological properties and water distribution of pork meat batters and decrease the proportion of free water, suggesting that BSDF has great potential as an effective binder in comminuted meat products.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.935-949
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• 2016

In this paper, we present a novel authenticated group key distribution scheme for large and dynamic multicast groups without employing traditional symmetric and asymmetric cryptographic operations. The security of our scheme is mainly based on the basic theories for solving linear equations. In our scheme, a large group is divided into many subgroups, where each subgroup is managed by a subgroup key manager (SGKM) and a group key generation center (GKGC) further manages all SGKMs. The group key is generated by the GKGC and then propagated to all group members through the SGKMs, such that only authorized group members can recover the group key but unauthorized users cannot. In addition, all authorized group members can verify the authenticity of group keys by a public one-way function. The analysis results show that our scheme is secure and efficient, and especially it is very appropriate for secure multicast communications in large and dynamic client-server networks.

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.115-122
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• 1999

This paper presents a key distribution scheme based on the Yacobi scheme that does not use the secret key provided by key distribution center, but uses instead a random number generated y the user. The scheme is independent of the exposure of the secret key. this paper also presented the key distribution schemes based on the Diffie-Hellman (DH) and ID (identity). The schemes based on the solving of the discrete logarithm and prime resolution into factors are better on the expose of secret key. The proposed scheme based on the DH was applied to VSAT satellite communications and simulated on PC using Montgomery algorithm for modular and MD5 (Message Digest) for hashing function.

• Steel and Composite Structures
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• v.42 no.2
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• pp.257-264
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• 2022

The analysis of the progressive collapse resistance of structures is a well-known issue among structural engineers. Large-span reticulated dome structures are commonly utilized in large public buildings, necessitating research into their progressive collapse resistance to assure user safety. The most significant part of improving the structural resilience of reticulated domes is to evaluate their key elements. Based on a stiffness-based evaluation approach, this work offers a calculating procedure for element importance coefficient. For both original and damaged structures, evaluations are carried out using the global stiffness matrix and the determinant. The Kiewitt, Schwedler, and Sunflower reticulated domes are investigated to explore the distribution characteristic of element importance coefficients in the single-layer dome structures. Moreover, the influences of the load levels, load distributions, geometric parameters and topological features are also discussed. The results can be regarded as the initial concept design reference for single-layer reticulated domes.

• ALGAE
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• v.34 no.3
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• pp.217-228
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• 2019

The marine brown algal genus Colpomenia has a worldwide distribution, with five species reported in Korea and Japan. However, no studies to date attempted to identify the number of species and geographical distribution of Colpomenia along Chinese coast. To fill the biodiversity knowledge gap, we analyzed 63 mitochondrial cox3 and 62 mitochondrial atp6 sequences of Colpomenia specimens collected from 30 localities along the Chinese coast. Maximum likelihood and Bayesian inference trees suggest the presence of at least three Colpomenia species (i.e., C. peregrina, C. claytoniae, and C. sinuosa) in China. C. peregrina and C. claytoniae are documented for the first time. C. sinuosa was only found in the South China Sea and its distribution didn't overlap with that of C. peregrina which was found in the Yellow-Bohai Sea and the East China Sea. C. claytoniae appears to be confined to three isolated islands in the East and the South China Sea, where it occurs in sympatry with, respectively, C. peregrina and C. sinuosa. Future study can focus on comparing eco-physiological differences of Colpomenia species in response to environmental variables and exploring possible genetic hybridization / introgression at inter-specific contact zones.