• Korean Journal of Head & Neck Oncology
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• v.37 no.1
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• pp.47-51
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• 2021

Papillary thyroid carcinoma (PTC) typically has a good prognosis, but it frequently metastasizes to the regional lymph nodes. Although survival impact of lymph node metastasis is not clear, complementary treatment is generally added after surgery when lymphatic metastasis exists. Several previous studies have reported that the multifocal PTC is associated with poor prognosis and requires selective neck dissection to prevent regional lymph node metastasis, but they are under controversy. In this study, we present a 24-year-old female patient, diagnosed as PTC with intrathyroidal spread and regional lymph node metastases. Intrathyroidal spread of PTC can only be observed microscopically and is believed to have the similar origin of unicentric multifocal PTC. As multifocal PTC is highly associated with regional lymph node metastasis and requires an additional treatment, PTC with intrathyroidal spread may follow a similar clinical course and treatment plan. Here we report the case with a brief literature review and expect its attribution to further academic interest of treatment choice.

• The KIPS Transactions:PartC
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• v.14C no.3 s.113
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• pp.277-284
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• 2007

The routing algorithm many used in the wireless sensor network features the clustering method to reduce the amount of data transmission from the energy efficiency perspective. However, the clustering method results in high energy consumption at the cluster head node. Dynamic clustering is a method used to resolve such a problem by distributing energy consumption through the re-selection of the cluster head node. Still, dynamic clustering modifies the cluster structure every time the cluster head node is re-selected, which causes energy consumption. In other words, the dynamic clustering approaches examined in previous studies involve the repetitive processes of cluster head node selection. This consumes a high amount of energy during the set-up process of cluster generation. In order to resolve the energy consumption problem associated with the repetitive set-up, this paper proposes the Round-Robin Cluster Header (RRCH) method that fixes the cluster and selects the head node in a round-robin method The RRCH approach is an energy-efficient method that realizes consistent and balanced energy consumption in each node of a generated cluster to prevent repetitious set-up processes as in the LEACH method. The propriety of the proposed method is substantiated with a simulation experiment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5B
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• pp.480-488
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• 2009

A mobile ad-hoc network is an autonomous collection of wireless mobile nodes that organizes a temporary network without any network infrastructure. Due to node mobility, it is a challenging task to maintain the network topology. In this paper, we propose a stable clustering algorithm that uses node mobility for cluster formation. In the proposed algorithm, the node mobility is measured by counting the number of nodes entering into/leaving from its transmission range. The node having the lowest mobility is selected as a cluster head. For topology maintenance with reduced control overhead, the cluster head adaptively controls the broadcasting period of hello message to the measured node mobility. Through computer simulations, it is verified that the proposed algorithm outperforms previous clustering algorithms in terms of control overhead, the rate of node mobility changes and the number of cluster head changes.

• Korean Journal of Head & Neck Oncology
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• v.31 no.2
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• pp.11-15
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• 2015

Background and Objectives: This study aimed to analyze the features of patients with papillary thyroid carcinoma (PTC) recurred as distant metastases (DM). Materials and Method: We retrospectively reviewed and analyzed clinical records of 63 patients who were treated for PTC recurred as DM between 2000 and 2006. Univariate and multivariate analyses of various clinical factors were performed. Results: Male patients were 12, and female patients were 51. The 5- and 10-year survival rates for PTC recurred as DM were 85% and 73%, respectively. Size of tumor, multiplicity of tumor, lateral neck node metastasis, and RAI ablation therapy with other treatments such as surgery were associated with survival rate (p < 0.005) in univariate analysis. The lateral neck node metastasis[p =0.039, hazard ratio=2.2(95% CI. 1.18~3.24)] and multiple organ DM[p =0.041, hazard ratio=2.18(95% CI. 1.03~2.89)] were related to the survival in multivariate analysis. Conclusion: PTC recurred as DM is uncommon (2.2%). The size of tumor, the multiplicity of tumor, lateral neck node metastasis and RAI ablation therapy with other treatments for DM were revealed as associated factors for the survival. Evaluation of DM should be considered in patients with PTC during long-term follow-up.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.1
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• pp.87-93
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• 2013

MANET has the advantage of having the flexibility to build easily a network in a difficult situation that builds a wired network. But, data transmission errors by movement of nodes and eavesdropping by wireless communications have become a problem of security. Authentication service is the most essential in order to overcome these problems and operate network stably. In this paper, we propose 3-tiers authentication structure to exclude of malicious node and operate stable network through more systematic and thorough node authentication. After network is composed into a cluster, cluster head which play CA role is elected. Among these, the highest-CA is elected. The highest-CA receives certificates to cluster head and the cluster head evaluates trust value of their member nodes. Authentication technique which issues member node key is used. We compared PSS and experimented to evaluate performance of proposed scheme in this paper and efficiency of the proposed technique through experience was confirmed.

• Journal of KIISE:Information Networking
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• v.32 no.6
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• pp.659-667
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• 2005

A Mobile Ad Hoc Network(MANET) is a multi hop wireless network with no prepared base stations or centralized administrations, where flocks of peer systems gather and compose a network. Each node operates as a normal end system in public networks. In addition to it, a MANET node is required to work as a router to forward traffic from a source or intermediate node to others. Each node operates as a normal end system in public networks, and further a MANET node work as a router to forward traffic from a source or intermediate node to the next node via routing path. Applications of MANET are extensively wide, such as battle field or any unwired place; however, these are exposed to critical problems related to network management, node's capability, and security because of frequent and dynamic changes in network topology, absence of centralized controls, restricted usage on network resources, and vulnerability oi mobile nodes which results from the special MANET's character, shared wireless media. These problems induce MANET to be weak from security attacks from eavesdropping to DoS. To guarantee secure authentication is the main part of security service In MANET because networks without secure authentication are exposed to exterior attacks. In this paper, a multistage authentication strategy based on CGSR is proposed to guarantee that only genuine and veritable nodes participate in communications. The proposed authentication model is composed of key manager, cluster head and common nodes. The cluster head is elected from secure nodes, and key manager is elected from cluster heads. The cluster head will verify other common nodes within its cluster range in MANET. Especially, ID of each node is used on communication, which allows digital signature and blocks non repudiation. For performance evaluation, attacks against node authentication are analyzed. Based on security parameters, strategies to resolve these attacks are drawn up.

• Korean Journal of Head & Neck Oncology
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• v.26 no.2
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• pp.221-224
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• 2010

Papillary thyroid carcinoma frequently invades the lymph node, trachea, esophagus and perithyroid tissue. However, direct extension to posterior pharyngeal area is known to be rare. A 64-year-old male was referred to our clinic presenting as posterior pharyngeal mass during gastrofiberscopy. The neck CT scan showed soft tissue mass in retropharynx and lymph node in right level III with calcifications. We performed the total thyroidectomy with selective(level II, III, IV) and anterior compartment neck dissection. In operative findings, the right thyroid mass were connected to the retropharynx through the posterior portion of inferior constrictor muscle. Histopathologic findings revealed the papillary thyroid carcinoma extended to retropharynx. We report a unique case with a literature review.

• International Journal of Computer Science & Network Security
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• v.21 no.1
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• pp.6-11
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• 2021

Routing protocols play a pivotal role in the energy management and lifespan of any Wireless Sensor Network. Lower network lifetime has been one of the biggest concerns in LEACH protocol due to dead nodes. The LEACH protocol suffers from uneven energy distribution problem due to random selection of a cluster head. The cluster head has much greater responsibility compared to other non- cluster head nodes and consumes greater energy for its roles. This results in early dead nodes due to energy lost for the role of cluster- head. This study proposes an approach to balance the energy consumption of the LEACH protocol by using a semi-deterministic opportunity coefficient to select the cluster head. This is calculated in each node with the battery energy level and node ID. Ultimately, based on the opportunity cost, cluster head will be selected and broadcasted for which other nodes with higher opportunity cost will agree. It minimizes the chances of nodes with lower battery level being elected as cluster head. Our simulation experiments demonstrate that cluster heads chosen using our proposed algorithm perform better than those using the legacy LEACH protocol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.9
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• pp.772-779
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• 2012

In the current MANET, DOS or DDOS attacks are increasing, but as MANET has limited bandwidth, computational resources and battery power, the existing traceback mechanisms can not be applied to it. Therefore, in case of traceback techniques being applied to MANET, the resource of each node must be used efficiently. However, in the traceback techniques applied to an existing ad hoc network, as a cluster head which represents all nodes in the cluster area manages the traceback, the overhead of the cluster head shortens each node's life. In addition, in case of multi-hop clustering, as one Cluster head manages more node than one, its problem is getting even worse. This paper proposes TNA(Traceback against Network Attacks) based on multihop clustering using the depth of tree structure in order to reduce the overhead of distributed information management.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.8
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• pp.889-897
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• 2014

With the development of wireless communication and sensor technology, sensor network applications in various fields have been applied. To minimize the power consumption of sensors in sensor network is one of the important factors in oder to extend the system life. The power consumption of each sensor within sensor network can be different depending on the communication method between head(sink) node and its node. In this paper, we propose a new hierarchical communication method to minimize the power consumption of each sensor. The proposed method divides the area of sensor network into four areas using divide-and-conquer method and selects the nearest node to head node in each area as a child node of the node. Next the hierarchical tree in the same way is constructed recursively until each area is no longer divided. Each sensor can communicate to head node using this hierarchical tree. The proposed results were compared with the previous methods through simulation, and showed excellent results in the energy efficiency of sensor network.