• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.345-355
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• 2019

Use of the reconstructed fuel assemblies from partially burnt nuclear fuel pins is analyzed. This reutilization option is a potential candidate technique to make better use of the nuclear resources. Standard two step method is used to calculate node i.e. fuel assembly average burnup and then pin by pin ${\eta}$ values are reconstructed to ascertain the residual reactivity in the used fuel pins. Fuel pins with ${\eta}$ > 1:0 are used to reconstruct to-be-reused fuel assemblies. These reconstructed fuel assemblies are burnt during the cycle 3, 4, 5 and 6 of a 1000 MW PWR core by replacing fresh, once burnt and twice burnt fuel assemblies of the reference core configurations. It is concluded that using reconstructed fuel assemblies for the fresh fuel affect dearly on the cycle length (>50 EFPD) when more than 16 fresh fuel assemblies are replaced. However, this loss is less than 20 days if the number of fresh fuel assemblies is less than eight. For the case of replacing twice burned fuel, cycle length could be increased slightly (10 days or so) provided burnt fuel pins from other reactors were also available. Reactor safety parameters, like axial off set (< ${\pm}10%$), Doppler temperature coefficient (<0), moderator temperature coefficient at HFP (<0) are always satisfied. Though, 2D and 3D pin peaking factors are satisfied (<1:55) and (<2:52) respectively, for the cases using eight or less reconstructed fuel assemblies only.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.495-497
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• 2013

Wireless sensor networks (WSNs) have emerged as an attractive and key research area over the last decade. Time synchronization is a vital part of infrastructure for any distributed system. In embedded sensor networks, time synchronization is an essential service for correlating data among nodes and communication scheduling. This is realized by exchanging messages that are time stamped using the local clocks on the nodes. Various time synchronization protocols have been proposed aiming to attain high synchronization accuracy, high efficiency and low communication overhead. However, it requires that the time between resynchronization intervals to be as large as possible to obtain a system which is energy efficient having low communication overhead. This paper presents a simple but effective skew compensation algorithm that measures the skew rate of the sensor nodes with respect to the reference node and calibrates itself to compensate for the difference in the frequencies of the nodes. The proposed method can be incorporated with any existing time synchronization protocol for WSNs.

• International Journal of Computer Science & Network Security
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• v.22 no.12
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• pp.212-216
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• 2022

Space based constellation network is a kind of ad hoc network in which users are self-organized without center node. In space based constellation network, users are allowed to enter or leave the network at any given time. Thus, the number of active users is an unknown and time-varying parameter, and the performance of the network depends on how accurately this parameter is estimated. The so-called problem of active user identification, which consists of determining the number and identities of users transmitting in space based constellation network is discussed and a novel active user identification method is proposed in this paper. Active user identification code generated by transmitter address code and receiver address code is used to spread spectrum. Subspace-based method is used to process received signal and judgment model is established to identify active users according to the processing results. The proposed method is simulated under AWGN channel, Rician channel and Rayleigh channel respectively. Numerical results indicate that the proposed method obtains at least 1.16dB E_b/N₀ gains compared with reference methods when miss alarm rate reaches 10^-3.

• Journal of Digestive Cancer Reports
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• v.7 no.1
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• pp.13-17
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• 2019

Stomach cancer is the fifth most common malignancy in the world. The incidence of stomach cancer is declining worldwide, however, gastric cancer still remains the third most common cause of cancer death. The tumor, node, and metastasis (TNM) staging system has been frequently used as a method for cancer staging system and the most important reference in cancer treatment. In 2016, the classification of gastric cancer TNM staging was revised in the 8^th American Joint Committee on Cancer (AJCC) edition. There are several modifications in stomach cancer staging in this edition compared to the 7^th edition. First, the anatomical boundary between esophagus and stomach has been revised, therefore the definition of stomach cancer and esophageal cancer has refined. Second, N3 is separated into N3a and N3b in pathological classification. Patients with N3a and N3b revealed distinct prognosis in stomach cancer, and these results brought changes in pathological staging. Several large retrospective studies were conducted to compare staging between the 7^th and 8^th AJCC editions including prognostic value, stage grouping homogeneity, discriminatory ability, and monotonicity of gradients globally. The main objective of this review is to evaluate the clinical and pathological implications of AJCC 8^th staging classification in the stomach cancer.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2172-2194
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• 2023

A variational nodal method (VNM) with unstructured-mesh is presented for solving steady-state and dynamic neutron diffusion equations. Orthogonal polynomials are employed for spatial discretization, and the stiffness confinement method (SCM) is implemented for temporal discretization. Coordinate transformation relations are derived to map unstructured triangular nodes to a standard node. Methods for constructing triangular prism space trial functions and identifying unique nodes are elaborated. Additionally, the partitioned matrix (PM) and generalized partitioned matrix (GPM) methods are proposed to accelerate the within-group and power iterations. Neutron diffusion problems with different fuel assembly geometries validate the method. With less than 5 pcm eigenvalue (k_eff) error and 1% relative power error, the accuracy is comparable to reference methods. In addition, a test case based on the kilowatt heat pipe reactor, KRUSTY, is created, simulated, and evaluated to illustrate the method's precision and geometrical flexibility. The Dodds problem with a step transient perturbation proves that the SCM allows for sufficiently accurate power predictions even with a large time-step of approximately 0.1 s. In addition, combining the PM and GPM results in a speedup ratio of 2-3.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.6
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• pp.1599-1618
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• 2024

Access control has always been one of the effective methods to protect data security. However, in new computing environments such as big data, data resources have the characteristics of distributed cross-domain sharing, massive and dynamic. Traditional access control mechanisms are difficult to meet the security needs. This paper proposes CACM-MMSR to solve distributed cross-domain access control problem for massive resources. The method uses blockchain and smart contracts as a link between different security domains. A permission decision model migration method based on access control logs is designed. It can realize the migration of historical policy to solve the problems of access control heterogeneity among different security domains and the updating of the old and new policies in the same security domain. Meanwhile, a semantic reasoning-based permission decision method for unstructured text data is designed. It can achieve a flexible permission decision by similarity thresholding. Experimental results show that the proposed method can reduce the decision time cost of distributed access control to less than 28.7% of a single node. The permission decision model migration method has a high decision accuracy of 97.4%. The semantic reasoning-based permission decision method is optimal to other reference methods in vectorization and index time cost.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.5
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• pp.265-273
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• 2002

With the explosive growth of WWW traffic, there is an increasing demand for the high performance Web servers to provide a stable Web service to users. The cluster-based Web server is a solution to core with the heavy access from users, easily scaling the server according to the loads. In the cluster-based Web sewer, a back-end node may not be able to serve some HTTP requests directly because it does not have the requested contents in its main memory. In this case, the back-end node has to retrieve the requested contents from its local disk or other back-end nodes in the cluster. To reduce service latency, we introduce a new prefetch scheme. The back-end nodes predict the next HTTP requests and prefetch the contents of predicted requests before the next requests arrive. We develop three prefetch algorithms bated on some useful information gathered from many clients'HTTP requests. Through trace-driven simulation, the service latency of the prefetch scheme is reduced by 10 ~ 25% as compared with no prefetch scheme. Among the proposed prefetch algorithms, Time and Access Probability-based Prefetch (TAP2) algorithm, which uses the access probability and the inter-reference time of Web object, shows the best performance.

• Journal of Gastric Cancer
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• v.1 no.3
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• pp.180-186
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• 2001

Purpose: The prognosis for early gastric cancer (EGC) is favorable, and the 10-year disease-specific survival rate is reported to be around $90\%$. The absolute number of recurred EGC is too small to assess the risk factors, so recruitment of a large number of cases for statistical analysis is very difficult. We carried out this study to analyze the incidence and the patterns of recurrence of EGC and to identify the clinicopathological risk factors for recurrence of EGC. Materials and Methods: The authors retrospectively investigated the follow-up records of 1418 patients who underwent a curative resection for EGC from Jan. 1984 to Dec. 1999 at the Korea Cancer Center Hospital and analyzed them with special reference to cancer recurrence. Results: In this retrospective study of 1418 cases, 43 patients died of a recurrence of gastric cancer, and 105 patients died of unrelated causes. The five-year and the ten-year overall survival rates were $89.6\%$ and $81.7\%$, respectively, while the five-year and the ten-year diseasespecific survival rates were $96.5\%$ and $94.3\%$, respectively. The recurrence patterns of the 45 recurred EGC were hematogenous metastasis (19 cases), lymph node (L/N) metastasis (8 cases), locoregional recurrence (2 cases), peritoneal seeding (3 cases), and combined form (13 cases). The mean time interval to recurrence was 38.6 months, and the number of delayed recurred cases after 5 years was 10 ($22.2\%$). Of the clinicopathologic factors, depth of invasion, L/N metastasis, macroscopic type, lymphatic invasion, and vessel invasion, were significant risk factors in the univariate analysis. However, in the multivariate analysis, only L/N metastasis was an independent prognostic factor. Conclusion: Based on the results of this study, L/N metastasis is an independent prognostic factor. Thus, in patients with node-positive disease, adjuvant therapy might be considered, and long-term close follow-up might facilitate early detection and treatment of recurrent disease due to delayed recurrence.

• Korean Journal of Head & Neck Oncology
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• v.24 no.1
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• pp.47-52
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• 2008

Purpose：The incidence of papillary thyroid microcarcinoma(PTMC) has increased due to the widespread use of high resolution ultrasonography and fine-needle aspiration biopsy. However, the clinical and biologic behaviors of PTMC is debatable. The aim of this study was to describe clinicopathologic features of PTMC and to suggest whether tumor size(5mm) might prove the useful parameter for determining the surgical strategy in PTMC. Material and Methods：From Jan. 2000 to Dec. 2005, 1355 of 2678 patients with papillary thyroid carcinoma were identified as having PTMC, based on tumor size${\leq}$10mm(50.6%). Among patients with PTMC, we further separated tumors<5mm(minute group：group M) from those 5 to 10mm(tiny group：group T). We compared the clinicopathological characteristics and the TNM stagings between two groups. Results：There were 114(8.4%) men and 1241(91.6%) women with a median age of 47 years(range；13-79). During a mean follow-up of 47.3(range；22-93), 13 patients(1.0%) developed locoregional recurrences and 3 patients(0.2%) showed distant metastases at initial presentation. Statistical analysis revealed that the presence of extracapsular invasion(p<0.0001), invasion to adjacent structure(p<0.0001), multifocality(p<0.0001), central lymph node metastasis(p<0.0001), and lateral lymph node metastasis(p<0.0001) were all significantly higher in tiny group(tumor${\geq}$5mm). Furthermore, minute group demonstrated a significantly lower tumor stage(AJCC TNM classification) compared with tiny group(p<0.0001). Conclusion：Patients with PTMC have a favorable treatment outcomes, although the distinction needs to be made with reference to the clinicopathologic behaviors. It would be reasonable to consider that tumor size(5mm) would be useful parameter for the treatment strategy of PTMC.

• Journal of Korean Society of Transportation
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• v.17 no.2
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• pp.55-68
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• 1999

Many ITS services require map databases in digital form to meet desired needs. Due to the dynamic nature of ITS and the sheer diversity of applications, the design and development of spatial databases to meet those needs pose a major challenge to both the public and private sectors. This challenge is further complicated by the necessity to transfer locationally referenced information between different kinds of databases and spatial data handling systems so that ITS products will work seamlessly across the region and nation. The Purpose of this paper is to develop the framework-models commonly to reference locations in the various applications and systems-the ITS Map Datum and LRS(Location Referencing System). The ITS Map Datum consists of the around control points which are the prime intersections (nodes) of the nationwide road network In this study, the major points have been determined along wish link-node modeling procedure. LRS, defined as a system for determining the position (location) of an entity relative to other entities or to some external frame of reference, has also been set up using CSOM type method. The method has been implemented using ArcView GIS software over the Kangnam and Seocho districts in the city of Seoul, showing that the implemented LRS scheme can be used successfully elsewhere. With the proper advent of the K.ITS architecture and services, the procedure can be used to improve the data sharing and to inter operate among systems, enhancing the efficiency both in terms of money and time.