• Journal of KIISE
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• v.42 no.3
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• pp.408-412
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• 2015

In base station based networks, traffic overload at the base station is inevitable. Peer-to-peer DTN which disperses the traffic overhead to each node can relieve the traffic overload at the base station. To increase the message delivery ratio and reduce the message overhead, we present novel routing using mobility information which can be obtained from each node, unlike the existing flooding based routings. In the proposed routing scheme, the routing decision metric, which is defined based on the node mobility information, is computed by using the expected distance between each node to the destination. The message is copied to other nodes that have lower expected distance to the destination than the value for the node willing to copy the message. We conducted simulations by using both a random mobility model and a real mobility trace to compare the performance of the proposed routing scheme to the existing routing scheme that does not utilize the mobility information. The performance evaluation showed the proposed routing successfully delivers messages with 10% to 30% less copies compared to previously proposed routing schemes.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.8
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• pp.4117-4123
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• 2016

Background: Methylation of promoter 2 of the SHP1 gene is epithelial cell specific, with reported potential as a lymph node metastatic marker. Objective: To demonstrate SHP1-P2 methylation-specific quantitative PCR effectiveness in detecting colorectal cancer (CRC) DNA in lymph nodes. Materials and Methods: SHP1-P2 methylation levels were measured in lymph nodes of CRC patients and compared with pathological findings and patient prognosis. Results: Lymph nodes of CRC metastatic patients without microscopically detectable cancer cells had higher SHP1-P2 methylation levels than lymph nodes of controls (p<0.001). In addition, a higher SHP1-P2 methylation level was associated with a shorter duration until adverse disease events, metastasis, recurrence and death (r2 = 0.236 and p value = 0.048). Studying two cohorts of 74 CRC patients without microscopic lymph node metastases showed that only the cohort containing samples with high SHP1-P2 methylation levels had a significant hazard ratio of 3.8 (95%CI = 1.02 to 14.2). Conclusions: SHP1-P2 methylation PCR can detect CRC DNA in lymph nodes even if cancer cells are not visible under a microscope, confirming applicability as a potential universal lymph node metastatic marker.

• Journal of Gastric Cancer
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• v.16 no.3
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• pp.161-166
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• 2016

Purpose: Lymph node (LN) metastasis is the best prognostic indicator in non-distant metastatic advanced gastric cancer. This study aimed to assess the prognostic value of various clinicopathologic factors in node-negative advanced gastric cancer. Materials and Methods: We retrospectively analyzed the clinical records of 254 patients with primary node-negative stage T2~4 gastric cancer. These patients were selected from a pool of 1,890 patients who underwent radical resection at Memorial Jin-Pok Kim Korea Gastric Cancer Center, Inje University Seoul Paik Hospital between 1998 and 2008. Results: Of the 254 patients, 128 patients (50.4%), 88 patients (34.6%), 37 patients (14.6%), and 1 patient (0.4%) had T2, T3, T4a, and T4b tumors, respectively. In a univariate analysis, operation type, T-stage, venous invasion, tumor size, and less than 15 LNs significantly correlated with tumor recurrence and cumulative overall survival. In a multivariate logistic regression analysis, tumor size, venous invasion, and less than 15 LNs significantly and independently correlated with recurrence. In a multivariate Cox proportional hazards analysis, tumor size (hazard ratio [HR]: 2.926; 95% confidence interval [CI]: 1.173~7.300; P=0.021), venous invasion (HR: 3.985; 95% CI: 1.401~11.338; P=0.010), and less than 15 LNs (HR: 0.092; 95% CI: 0.029~0.290; P<0.001) significantly correlated with overall survival. Conclusions: Node-negative gastric cancers recurred in 8.3% of the patients in our study. Tumor size, venous invasion, and less than 15 LNs reliably predicted recurrence as well as survival. Aggressive postoperative treatments and timely follow-ups should be considered in cases with these characteristics.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.8
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• pp.1438-1443
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• 2016

In this paper, we investigate the effect of multiple antennas at a relay node on the performance of physical-layer network coding (PNC) in the two-way relay channel (TWRC). We assume that two source nodes have a single antenna and the relay node has multiple antennas. We extend the conventional TWRC environment with a signle antenna at both relay and source nodes to the case of multiple antennas at the relay node. In particular, we consider two decoding strategies: separate decoding (SD) and direct decoding (DD). The SD decodes each packet from the two sources and performs the network coding with bit-wise exclusive OR (XOR) operation, while the DD decodes the network-coded packet from the two sources. Note that both decoding strategies are based on log-likelihood ratio (LLR) computation. It is shown that the bit error rate (BER) performance becomes significantly improved as the number of antennas at the relay node.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4411-4431
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• 2014

Mobile ad hoc networks (MANETs) have recently gained increased interest due to the widespread use of smart mobile devices. Group communication applications, serving for better cooperation between subsets of business members, become more significant in the context of MANETs. Multicast routing mechanisms are very useful communication techniques for such group-oriented applications. This paper deals with multicast routing problems in terms of stability and scalability, using the concept of stable core. We propose LMRSC (Lightweight Multicast Routing Based on Stable Core), a lightweight multicast routing technique for MANETs, in order to avoid periodic flooding of the source messages throughout the network, and to increase the duration of multicast routes. LMRSC establishes and maintains mesh architecture for each multicast group member by dividing the network into several zones, where each zone elects the most stable node as its core. Node residual energy and node velocity are used to calculate the node stability factor. The proposed algorithm is simulated by using NS-2 simulation, and is compared with other multicast routing mechanisms: ODMRP and PUMA. Packet delivery ratio, multicast route lifetime, and control packet overhead are used as performance metrics. These metrics are measured by gradual increase of the node mobility, the number of sources, the group size and the number of groups. The simulation performance results indicate that the proposed algorithm outperforms other mechanisms in terms of routes stability and network density.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.8
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• pp.1890-1910
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• 2013

Routing overlay offers an ideal methodology to improve the end-to-end communication performance by deriving a backup path for any node pair. This paper focuses on a challenging issue of selecting a proper backup path to bypass the failures on the default path with high probability for any node pair. For existing backup path selection approaches, our trace-driven evaluation results demonstrate that the backup and default paths for any node pair overlap with high probability and hence usually fail simultaneously. Consequently, such approaches fail to derive a robust backup path that can take over in the presence of failure on the default path. In this paper, we propose a three-phase RBPS approach to identify a proper and robust backup path. It utilizes the traceroute probing approach to obtain the fine-grained topology information, and systematically employs the grid quorum system and the Bloom filter to reduce the resulting communication overhead. Two criteria, delay and fault-tolerant ability on average, of the backup path are proposed to evaluate the performance of our RBPS approach. Extensive trace-driven evaluations show that the fault-tolerant ability of the backup path can be improved by about 60%, while the delay gain ratio concentrated at 14% after replacing existing approaches with ours. Consequently, our approach can derive a more robust and available backup path for any node pair than existing approaches. This is more important than finding a backup path with the lowest delay compared to the default path for any node pair.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.4
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• pp.213-220
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• 2009

Purpose: The present study was aimed to examine the usefulness of 18F-FDG PET/CT in the evaluation of cervical lymph node metastasis in patients with oral cancer. Materials and methods: Twenty-two patients who underwent neck dissection to treat oral cancer were subjected for examination. The cervical node metastasis was evaluated by means of clinical examination, CT scan, PET, and histologic examination. By comparing the results of each examination modality with those of histologic examination, it's sensitivity, specificity, positive predictive value, and negative predictive value were determined. Results: The oral cancer was more frequent in males with a ratio of 2.14:1. The sixth decade showed the highest incidence in age distribution with mean of $56{\pm}16$. Histologic findings showed that squamous cell carcinoma was the most common (15 patients), and mucoepidermoid carcinoma (3), malignant melanoma (2), and adenoid cystic carcinoma and ghost cell odontogenic carcinoma (1 each), in order. In most cases, wide surgical excision of the primary cancer and neck dissection was performed, followed by reconstruction with free flaps when necessary. When comparing the results of each examination modality with those of the histologic examination, clinical examination showed sensitivity, specificity, positive predictive value, and negative predictive value at 11%, 85%, 33%, and 58%, respectively. CT scans showed at 67%, 77%, 67%, and 77%, while $^{18}F$-FDG PET/CT at 78%, 77%, 70%, and 83%, respectively. Conclusions: These results suggest that PET is more useful, compared with clinical examination and CT scans, in the evaluation of cervical lymph node metastasis in patients with oral cancer.

• International Journal of Computer Science & Network Security
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• v.23 no.1
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• pp.153-163
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• 2023

This study is situated in the context of intelligent transport systems, where in-vehicle devices assist drivers to avoid accidents and therefore improve road safety. The vehicles present in a given area form an ad' hoc network of vehicles called vehicular ad' hoc network. In this type of network, the nodes are mobile vehicles and the messages exchanged are messages to warn about obstacles that may hinder the correct driving. Node mobilities make it impossible for inter-node communication to be end-to-end. Recognizing this characteristic has led to delay-tolerant vehicular networks. Embedded devices have small buffers (memory) to hold messages that a node needs to transmit when no other node is within its visibility range for transmission. The performance of a vehicular delay-tolerant network is closely tied to the successful management of the nodes' transit buffer. In this paper, we propose a message transit buffer management model for nodes in vehicular delay tolerant networks. This model consists in setting up, on the one hand, a policy of dropping messages from the buffer when the buffer is full and must receive a new message. This drop policy is based on the concept of intermediate node to destination, queues and priority class of service. It is also based on the properties of the message (size, weight, number of hops, number of replications, remaining time-to-live, etc.). On the other hand, the model defines the policy for selecting the message to be transmitted. The proposed model was evaluated with the ONE opportunistic network simulator based on a 4000m x 4000m area of downtown Bouaké in Côte d'Ivoire. The map data were imported using the Open Street Map tool. The results obtained show that our model improves the delivery ratio of security alert messages, reduces their delivery delay and network overload compared to the existing model. This improvement in communication within a network of vehicles can contribute to the improvement of road safety.

• Journal of Gastric Cancer
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• v.24 no.2
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• pp.185-198
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• 2024

Purpose: Peritoneal washing cytology (PWC) is a widely used diagnostic tool for detecting peritoneal metastasis of advanced gastric cancer. However, the prognosis of patients with positive PWC remains poor even after gastrectomy, and treatments vary among institutions and eras. In this study, we identified the clinical factors that can help predict cytology-positive (CY(+)) gastric cancer. Materials and Methods: We retrospectively reviewed the national data of patients with gastric cancer from 2019, as provided by the Information Committee of the Korean Gastric Cancer Association. Of the 13,447 patients with gastric cancer, 3,672 underwent PWC. Based on cytology results, we analyzed the clinicopathological characteristics and assessed the possibility of CY(+) outcomes in relation to T and N stages. Results: Of the 3,270 patients who underwent PWC without preoperative chemotherapy, 325 were CY(+), whereas 2,945 were negative. CY(+) was more commonly observed in patients with Borrmann type IV gastric cancer, an undifferentiated histological type, and advanced pathological stages. Multivariate analysis revealed Borrmann type IV (odds ratio [OR], 1.821), tumor invasion to T3-4 (OR, 2.041), and lymph node metastasis (OR, 3.155) as independent predictors of CY(+). Furthermore, for circular tumor location, the N stage emerged as a significant risk factor for CY(+), particularly when the tumor was located on the posterior wall (PW) side. Conclusions: Lymph node metastasis significantly affects CY(+) outcomes, particularly when the tumor is located on the PW side. Therefore, PWC should be considered not only in suspected serosal exposure cases but also in cases of lymph node metastasis.

• Steel and Composite Structures
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• v.30 no.1
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• pp.31-46
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• 2019

In the present study, the various dynamic properties of MWCNT embedded fiber reinforced polymer uniform and tapered composite (MWCNT-FRP) plates are investigated. Various configurations of a tapered composite plate with ply-drop off and uniform composite plate have been considered for the development of the finite element formulation and experimental investigations. First order shear deformation theory (FSDT) has been used to derive the kinetic and potential energy equations of the hybrid composite plates by including the effect of rotary inertia, shear deformation and non-uniformity in thickness of the plate. The governing equations of motion of FRP composite plates without and with MWCNT reinforcement are derived by considering a nine- node rectangular element with five degrees of freedom (DOF) at each node. The effectiveness of the developed finite element formulation has been demonstrated by comparing the natural frequencies and damping ratio of FRP composite plates without and with MWCNT reinforcement obtained experimentally. Various parametric studies are also performed to study the effect of CNT volume fraction and CNT aspect ratio of the composite plate on the natural frequencies of different configurations of CNT reinforced hybrid composite plates. Further the forced vibration analysis is performed to compare the dynamic response of the various configurations of MWCNT-GFRP composite plate with GFRP composite plate under harmonic excitations. It was observed that the fundamental natural frequency and damping ratio of the GFRP composite plate increase approximately 8% and 37% respectively with 0.5wt% reinforcement of MWCNT under CFCF boundary condition. The natural frequencies of MWCNT-GFRP hybrid composite plates tend to decrease with the increase of MWCNT volume fraction beyond 2% due to agglomeration of CNT's. It is also observed that the aspect ratio of the CNT has negligible effect on the improvement of dynamics properties due to randomly orientation of CNT's.