• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.1
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• pp.30-35
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• 2002

Dynamic routing uses routing protocols to select the best routes and to update the routing table. RP (Routing Information Protocol)using a distance-vector algorithm becomes generally known a routing protocol on the network. RIP selects the route with the lowest "hop count" (metric) as the best route. but RIP has a serious shortcoming. a mP router cannot maintain a complete routing table for a network that has destinations more than 15 hops away. To overcome this defect, It uses the OSPF (Open Shortest Path First) of link -state protocols developed for TCP/IP. It is suitable for very large networks and provides several advantages over RIP. This paper analyzes the traffic and the link efficiency between two protocols such as message delivery and delay, link utilization, message counts on the same network.e network.

• Journal of Magnetics
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• v.20 no.1
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• pp.11-20
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• 2015

In this work, Monte Carlo simulation was employed to model the stretchable Ising monolayer film to investigate the effect of the spatial distance variation among magnetic atoms on magnetic behavior of the film. The exchange interaction was considered as functions of initial interatomic distance and the stretched distance (or the strain). Following Bethe-Slater picture, the magnetic exchange interaction took the Lennard-Jones potential-like function. Monte Carlo simulations via the Wolff and Metropolis algorithms were used to update the spin systems, where equilibrium and dynamic magnetic profiles were collected. From the results, the strain was found to have strong influences on magnetic behavior, especially the critical behavior. Specifically, the phase transition point was found to either increase or decrease depending on how the exchange interaction shifts (i.e. towards or away from the maximum value). In addition, empirical functions which predict how the critical temperatures scale with initial interatomic distance and the strain were proposed, which provides qualitatively view how to fine tune the magnetic critical point in monolayer film using the substrate modification induced strain.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.1032-1035
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• 2012

클라우드 컴퓨팅을 제공하기 위해 서비스 제공자는 대용량의 중앙집중형 데이터 센터를 구축하고, 클라이언트는 어플리케이션 소프트웨어와 데이터베이스를 이러한 데이터 센터에 저장한다. 클라우드 컴퓨팅을 사용하면 컴퓨팅 자원을 구축하는 비용을 절감할 수 있다는 장점이 있다. 문제는 클라이언트가 데이터 센터와 서비스제공자를 완전히 신뢰할 수 없다는 것이다. 예를 들어, 클라우드에 저장된 파일이 손실되었을 때 서비스 제공자는 서비스의 신뢰도가 떨어지는 것을 막기 위해 이를 숨길 수 있다. 이때, 데이터가 저장 후에 손실되었다는 것을 증명하지 못하면, 그 피해는 클라이언트에게 돌아오게 된다. 따라서, 클라이언트의 데이터를 보호하기 위하여 무결성을 검증할 수 있는 적절한 기법을 적용하여야 한다. 대부분의 기존 연구에서는 public aditability와 dynamic data update를 동시에 지원하지 못하며, 이를 동시에 지원한다 하더라도 효율성이 떨어지는 문제가 있다. 본 논문에서는 클라우드 컴퓨팅에서 데이터 스토리지의 무결성을 검증하기 위한 기법을 제안한다. 제안하는 기법은 효율성, 동적 데이터 환경, public auditability를 설계목표로 한다. 블록 마다 서명을 생성해야 하는 이전 기법과 달리, 제안하는 기법은 한번의 서명으로 검증값을 생성하므로 데이터의 크기에 영향을 적게 받는다. 또한, 삽입, 삭제, 수정 등의 연산이 발생하는 동적 데이터 환경에서도 효과적으로 저장된 데이터의 무결성을 검증할 수 있게 설계하였다. 마지막으로 파일에 접근할 수 있는 클라이언트는 누구나 데이터의 무결성을 확인할 수 있으므로 public auditability를 제공한다.

• Structural Engineering and Mechanics
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• v.69 no.3
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• pp.317-326
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• 2019

This research aims to assess the tight seismic risk curve of the intake tower at Geumgwang reservoir by considering the recorded historical earthquake data in the Korean Peninsula. The seismic fragility, a significant part of risk assessment, is updated by using Bayesian inference to consider the uncertainties and computational efficiency. The reservoir is one of the largest reservoirs in Korea for the supply of agricultural water. The intake tower controls the release of water from the reservoir. The seismic risk assessment of the intake tower plays an important role in the risk management of the reservoir. Site-specific seismic hazard is computed based on the four different seismic source maps of Korea. Probabilistic Seismic Hazard Analysis (PSHA) method is used to estimate the annual exceedance rate of hazard for corresponding Peak Ground Acceleration (PGA). Hazard deaggregation is shown at two customary hazard levels. Multiple dynamic analyses and a nonlinear static pushover analysis are performed for deriving fragility parameters. Thereafter, Bayesian inference with Markov Chain Monte Carlo (MCMC) is used to update the fragility parameters by integrating the results of the analyses. This study proves to reduce the uncertainties associated with fragility and risk curve, and to increase significant statistical and computational efficiency. The range of seismic risk curve of the intake tower is extracted for the reservoir site by considering four different source models and updated fragility function, which can be effectively used for the risk management and mitigation of reservoir.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.9
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• pp.3258-3273
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• 2021

Malware is a severe threat to the computing system and there's a long history of the battle between malware detection and anti-detection. Most traditional detection methods are based on static analysis with signature matching and dynamic analysis methods that are focused on sensitive behaviors. However, the usual detections have only limited effect when meeting the development of malware, so that the manual update for feature sets is essential. Besides, most of these methods match target samples with the usual feature database, which ignored the characteristics of the sample itself. In this paper, we propose a new malware detection method that could combine the features of a single sample and the general features of malware. Firstly, a structure of Directed Cyclic Graph (DCG) is adopted to extract features from samples. Then the sensitivity of each API call is computed with Markov Chain. Afterward, the graph is merged with the chain to get the final features. Finally, the detectors based on machine learning or deep learning are devised for identification. To evaluate the effect and robustness of our approach, several experiments were adopted. The results showed that the proposed method had a good performance in most tests, and the approach also had stability with the development and growth of malware.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.4
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• pp.77-89
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• 2001

Recently, with the explosive growth of communication technologies, group oriented services such as teleconference and multi-player game are increasing. Access control to information is handled by secret communications with group keys shared among members, and efficient updating of group keys is vital to such secret communications of large and dynamic groups. In this paper, we employ (2,4)-tree as a key tree, which is one of height balanced trees, to reduce the number of key updates caused by join or leave of members. Especially, we use CBT(Core Based Tree) to gather network configurations of group members and reflect this information to key tree structure to update group keys efficiently when splitting or merging of subgroups occurs by network failure or recovery.

• Journal of Korean Neurosurgical Society
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• v.66 no.6
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• pp.611-617
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• 2023

The cervical spine plays a critical role in supporting the skull, maintaining horizontal gaze, and facilitating walking. Its unique characteristics, including the widest range of motion among spinal segments, have led to extensive research on cervical sagittal alignment. Various parameters have been proposed to evaluate cervical alignment, with studies investigating their clinical significance, correlation with symptoms, and implications for surgical interventions. Recent findings suggest that cervical sagittal alignment not only impacts the cervical spine but also influences global spine-pelvic alignment through compensatory mechanisms. This comprehensive review examines classical and new parameters of cervical sagittal alignment and considers the dynamic and muscular factors associated with it.

• Korean Journal of Radiology
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• v.25 no.5
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• pp.459-472
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• 2024

Hyperpolarized (HP) carbon-13 (¹³C) MRI represents an innovative approach for noninvasive, real-time assessment of dynamic metabolic flux, with potential integration into routine clinical MRI. The use of [1-¹³C]pyruvate as a probe and its conversion to [1-¹³C]lactate constitute an extensively explored metabolic pathway. This review comprehensively outlines the establishment of HP ¹³C-MRI, covering multidisciplinary team collaboration, hardware prerequisites, probe preparation, hyperpolarization techniques, imaging acquisition, and data analysis. This article discusses the clinical applications of HP ¹³C-MRI across various anatomical domains, including the brain, heart, skeletal muscle, breast, liver, kidney, pancreas, and prostate. Each section highlights the specific applications and findings pertinent to these regions, emphasizing the potential versatility of HP ¹³C-MRI in diverse clinical contexts. This review serves as a comprehensive update, bridging technical aspects with clinical applications and offering insights into the ongoing advancements in HP ¹³C-MRI.

• Journal of KIISE:Information Networking
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• v.37 no.1
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• pp.72-83
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• 2010

Group communication in a wireless mesh network is complicated due to dynamic intermediate mesh points, access control for communications between different administrative domains, and the absence of a centralized network controller. Especially, many-to-many multicasting in a dynamic mesh network can be modeled by a decentralized framework where several subgroup managers control their members independently and coordinate the inter-subgroup communication. In this study, we propose a topology-matching decentralized group key management scheme that allows service providers to update and deliver their group keys to valid members even if the members are located in other network domains. The group keys of multicast services are delivered in a distributed manner using the identity-based encryption scheme. Identity-based encryption facilitates the dynamic changes of the intermediate relaying nodes as well as the group members efficiently. The analysis result indicates that the proposed scheme has the advantages of low rekeying cost and storage overhead for a member and a data relaying node in many-to-many multicast environment. The proposed scheme is best suited to the settings of a large-scale dynamic mesh network where there is no central network controller and lots of service providers control the access to their group communications independently.

• Journal of Internet Computing and Services
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• v.14 no.5
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• pp.11-26
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• 2013

In the wireless Internet, it is so restrictive to use the IPSec. The MIPv4 IPSec's path cannot include wireless links. That is, the IPSec of the wireless Internet cannot protect an entire path of Host-to-Host connection. Also wireless circumstance keeps a path static during the shorter time, nevertheless, the IKE for IPSec SA agreement requires relatively long delay. The certificate management of IPSec PKI security needs too much burden. This means that IPSec of the wireless Internet is so disadvantageous. Our paper is to construct the Mobile IPSec proper to the wireless Internet which provides the host-to-host transport mode service to protect even wireless links as applying excellent WP-IBE scheme. For this, Mobile IPSec requires a dynamic routing over a path with wireless links. FA Forwarding is a routing method for FA to extend the path to a newly formed wireless link. The FA IPSec SA for FA Forwarding is updated to comply the dynamically extended path using Source Routing based Bind Update. To improve the performance of IPSec, we apply efficient and strong future Identity based Weil Pairing Bilinear Elliptic Curve Cryptography called as WP-IBE scheme. Our paper proposes the modified protocols to apply 6 security-related algorithms of WP-IBE into the Mobile IPSec. Particularly we focus on the protocols to be applied to construct ESP Datagram.