• Convergence Security Journal
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• v.12 no.6
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• pp.101-106
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• 2012

As the existing strategy of preventing DDoS(Distributed Denial of Service) attacks has limitations, this study is intended to suggest the more effective method of preventing DDoS attacks which reduces attack power and distributes attack targets. Currently, DDoS attacks have a wide range of targets such as individuals, businesses, labs, universities, major portal sites and financial institutions. In addition, types of attacks change from exhausting layer 3, network band to primarily targeting layer 7. In response to DDoS attacks, this study suggests how to distribute and decrease DDoS threats effectively and efficiently using Proxy Server Group and Dynamic DNS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.1955-1962
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• 2012

Recently the flow of information security has become a user-centered change. This is mostly breach of security by the normal and abnormal entering harmful files during user internet. Therefore, we would like to design security system that breach of security can be prevented in advance to improve using the reliability of DNS and system control in this paper. In other words, we would like to suggest method can be block randomly to access the site which information security system of user-centric is breached harmful files infected in user computer.

• Journal of the Korean Society of Physical Medicine
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• v.16 no.3
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• pp.55-64
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• 2021

PURPOSE: The purpose of this study was to apply dynamic neuromuscular stabilization (DNS) to subjects with forward head posture (FHP) and to compare its effects on respiratory function as against the conventional neck stabilization exercise and neck stretching and extensor strengthening exercises. METHODS: The whole-body posture measurement system was used to measure the degree of FHP, and a spirometer and a respiratory gas analyzer were used to measure the respiratory function. After the intervention was completed, the changes over time were analyzed in the DNS group, the neck stabilization exercise group, and the neck stretching and extensor strengthening exercise group. The inter-group difference in the changes was also analyzed. A repeated ANOVA was performed to compare the respiratory function according to the period between the three groups, and the least significant difference (LSD) method was used for the post hoc test. RESULTS: After the 6-week exercise period, respiratory functions, such as forced vital capacity (FVC), forced expiratory volume for 1 second (FEV1), forced expiratory volume for 1 sec/forced vital capacity (FEV1/FVC), maximum oxygen intake (VO₂max), and the volume of expired gas (VE), significantly improved according to the period (p < .05), but no inter-group differences were found. CONCLUSION: DNS is an effective training method, and can be applied along with neck stabilization exercise and neck stretching and extensor strengthening exercises, which are widely used in clinical practice, to people with FHP who cannot directly perform neck exercises to improve their respiratory function.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.12
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• pp.1849-1856
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• 2013

DOS attack, the short of Denial of Service attack is an internet intrusion technique which harasses service availability of legitimate users. To respond the DDoS attack, a lot of methods focusing attack source, target and intermediate network, have been proposed, but there have not been a clear solution. In this paper, we purpose the prevention of malicious activity and early detection of DDoS attack by detecting and removing the activity of botnets, or other malicious codes. For the purpose, the proposed method monitors the network traffic, especially DSN traffic, which is originated from botnets or malicious codes.

• International Commerce and Information Review
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• v.10 no.1
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• pp.139-154
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• 2008

This research want to discuss some issues about payment system of America. This research focuses on comparing ACH with Fedwire. Firstly Fedwire is the payment system for only large-dollar transfer(Large-Value Transfer System; LVTS), while ACH(Automated Clearing House)payment mainly applies a consumer account. Secondly ACH transaction is either credit or debit transfer, while Fedwire is only credit transfer. Thirdly the communication system of Fedwire has twoway method, telephonelike communication network, but ACH is oneway store and forward electronic mail. At present LVTS divides into RTGS(Real-Time Gross Settlement) and DNS(Deferred Net Settlement). However Fedwire uses either RTGS(instantaneous for every transaction) or DNS(net net transaction) but ACH uses only DNS(net net transaction). Fourthly ACH is substantially cheaper than the Fedwire payment. lastly security is important in both Fedwire and ACH, it is even more crucial in Fedwire In addition, for each transaction, Fedwire may entail individual instantaneous confirmation to the originator and notification to the receiver, whereas ACH do not.

• 한국IT서비스학회:학술대회논문집
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• 2008.05a
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• pp.578-581
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• 2008

전 세계적으로 급격한 컴퓨터 보급률 확대와 인터넷 활용인구의 증가에 힘입어 사회와 문화, 산업전반에 걸쳐 인터넷의 활용도는 눈부신 성장을 이어가고 있다. 하지만 기존의 IP 체계가 주소할당과 보안 등의 이유들로 많은 문제점들이 나타나고 있으며 이에 대한 해결방안으로 지금 전 세계는 IPv6로의 전환에 많은 연구와 노력을 기울이고 있다. 이러한 IP체계의 전환시점에서도 여전히 발생할 수 있는 DNS 주소 위변조 공격을 막고 안정적으로 도메인 네임 서비스를 사용자에게 제공할 수 있는 방안으로 DNSSEC을 개발하였다. 본 논문에서는 DNSSEC이 가지고 있는 과부하의 문제점을 분석하여 그에 대한 해결방안을 제안한다.

• Journal of computational fluids engineering
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• v.15 no.2
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• pp.35-40
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• 2010

In the present work, LES with new variational multiscale method is conducted on the fully developed channel flow with Reynolds number, 180 based on the friction velocity and the channel half width. Incompressible Navier-Stokes equations are integrated using finite element method with the basis function of NURBS. To solve space-time equations, Newton's method with two stage predictor multicorrector algorithm is employed. The code is parallelized using MPI. The computational domain is a rectangular box of size $2{\pi}{\times}2{\times}4/3{\pi}$ in the streamwise, wall normal and spanwise direction. Mean velocity profiles and velocity fluctuations are compared with the data of DNS. The results agree well with those of DNS and other traditional LES.

• 한국전산유체공학회:학술대회논문집
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• 2009.11a
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• pp.56-59
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• 2009

In the present work, LES with new variational multiscale method is conducted on the fully developed channel flow with Reynolds number is 180 based on the friction velocity and the channel half width. Incompressible Navier-Stokes equations are integrated using finite element method with the basis function of NURBS. To solve space-time equations, Newton's method with two stage predictor multicorretor algorithm is employed. The code is parallelized using MPI. The computational domain is a rectangular box of size $2{\pi}{\times}2{\times}4/3{\pi}$ in the streamwise, wall normal and spanwise direction. Mean velocity profiles and velocity fluctuations are compared with the data of DNS. The results agree well with those of DNS and other traditional LES.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.10
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• pp.1317-1325
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• 2000

A new efficient numerical method for computing three-dimensional, unsteady, incompressible flows is presented. To eliminate the restriction of CFL condition, a fully-implicit time advancement in which the Crank-Nicolson method is used for both the diffusion and convection terms, is adopted. Based on an approximate block LU decomposition method, the velocity -pressure decoupling is achieved. The additional decoupling of the intermediate velocity components in the convection term is made for the fully -implicit time advancement scheme. Since the iterative procedures for the momentum equations are not required, the velocity components decouplings bring forth the reduction of computational cost. The second-order accuracy in time of the present numerical algorithm is ascertained by computing decaying vortices. The present decoupling method is applied to minimal channel flow unit with DNS (Direct Numerical Simulation).

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.1
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• pp.147-153
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• 2015

Since the DoS(Denial of Service) attack is still an important vulnerable element in many web service sites, sites including public institution should try their best in constructing defensive systems. Recently, DDoS(Distributed Denial of Service) has been raised by prompting mass network traffic that uses NTP's monlist function or DoS attack has been made related to the DNS infrastructure which is impossible for direct defense. For instance, in June 2013, there has been an outbreak of an infringement accident where Computing and Information Agency was the target. There was a DNS application DoS attack which made the public institution's Information System impossible to run its normal services. Like this, since there is a high possibility in having an extensive damage due to the characteristics of DDoS in attacking unspecific information service and not being limited to a particular information system, efforts have to be made in order to minimize cyber threats. This thesis proposes a method for using TTL (Time To Live) value in IP header to detect DDoS attack with IP spoofing, which occurs when data is transmitted under the agreed regulation between the international and domestic information system.